Ornella Selmin
- Associate Research Professor, Nutritional Sciences
- Associate, Center for Toxicology
- Member of the Graduate Faculty
- (520) 626-6087
- Leon Levy Cancer Center, Rm. 3999A
- Tucson, AZ 85724
- selmin@arizona.edu
Degrees
- Ph.D. Molecular and Cellular Biology
- University of Padova, Padova, Italy
- Characterization of Anchorin II, a New Collagen Type II Receptor and Cellular Expression of Tropoelastin in the Developing Chick.
Work Experience
- University of Arizona, Arizona (2009 - 2011)
- University of Arizona, Arizona (2002 - 2009)
- University of Arizona, Arizona (1996 - 2002)
- NIEHS, NIH (1993 - 1996)
- VPI &SU (1990 - 1993)
Interests
Teaching
Mediterranean Diet and HealthNutrition and Cancer Prevention/DevelopmentEpigenetic regulation in breast and colon cancer development
Research
My training and research background are in the field of molecular and developmental biology. My research activities have focused on the role of exposure to environmental and dietary factors in the etiology of developmental and chronic diseases including inflammation and cancer. Specific research objectives have been 1) to identify the molecular mechanisms through which ubiquitous environmental pollutants induce congenital heart disease; 2) elucidating the signaling pathways through which dietary agents influence epigenetic regulation of proinflammatory and tumor suppressor genes such as the breast cancer-1 (BRCA-1) and cyclooxygenase-2 (COX-2) genes. As a principal investigator at The University of Arizona I have been responsible for more than a decade for the acquisition and administration of research funds, recruitment and training of laboratory personnel and students, and delivery of scientific and administrative reports including research manuscripts, presentation at conferences, annual and progress reports. As a Faculty of the University of Arizona I have contributed to interdisciplinary programs, development of multi-principal investigators grants, and cross-training of staff and students.
Courses
2023-24 Courses
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Nutritional Biology
NSC 408 (Spring 2024) -
Nutritional Biology
NSC 408 (Fall 2023)
2022-23 Courses
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Nutritional Biology
NSC 408 (Spring 2023) -
Nutritional Biology
NSC 408 (Fall 2022)
2021-22 Courses
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Nutritional Biology
NSC 408 (Spring 2022)
Scholarly Contributions
Chapters
- Donovan, M. G., Donovan, M. G., Selmin, O. I., & Romagnolo, D. F. (2019). Prevention of Breast Cancer by Food Bioactives in Relation to Cancer Subtypes: Epigenetic Mechanisms. In Epigenetics of cancer prevention. Academic Press. doi:10.1016/B978-0-12-812494-9.00015-9More infoAbstract Breast cancer is the most common type of cancer and the leading cause of mortality among women worldwide. Aberrations in epigenetic regulation of tumor-suppressor genes contribute to hereditary and sporadic breast cancers. Accumulating evidence suggests a role for dietary compounds as epigenetic modifiers of breast cancer risk. However, given that breast cancer is a heterogeneous disease, it is important to consider variations in the epigenetic profile and potential response to food compounds across breast cancer subtypes. In this chapter, we first summarize research evidence regarding differences in epigenotype across breast tumor subtypes with emphasis on changes in DNA methylation, histone modifications, and the expression of noncoding RNA. Second, we discuss the role of epigenetic mechanisms in the silencing of breast cancer 1 (BRCA1), selected as a prototype early-onset breast cancer gene and epigenetic target by environmental and endogenous compounds that activate the aryl hydrocarbon receptor (AhR). Third, we highlight research evidence about food components (e.g., resveratrol and genistein) as dietary preventatives against epigenetic repression of BRCA1 by AhR agonists and the development of estrogen receptor-negative and triple-negative breast cancer.
- Selmin, O. I., Romagnolo, A. P., & Romagnolo, D. F. (2019). Nuclear receptors and epigenetic regulation. In Advanced Nutrition. Springer International Publishing. doi:10.1007/978-3-319-55530-0_121
- Selmin, O. (2018). Mediterranean diet for the prevention of er-negative breast cancers: Molecular interactions of olive oil and vegetable bioactives in HER2-enriched and TNBC. In Molecular Nutrition: Cancer. Andrew Neilson and Eva Schmelz, Editors.
- Selmin, O. (2018). Prevention of breast cancer by food bioactives in relation to cancer subtypes; Epigenetic mechanisms.. In Epigenetics of Chemoprevention: Bishayee A, Editor.
- Selmin, O. (2017). Nutritional epigenetics of nuclear receptors in breast cancer.. In Handbook of Nutrition.. Elsevier.
- Donovan, M. G., Donovan, M. G., Selmin, O. I., Doetschman, T. C., & Romagnolo, D. F. (2016). Mediterranean Diet, Inflammatory Bowel Diseases, and Colon Cancer. In Mediterranean diet. Humana Press, Cham. doi:10.1007/978-3-319-27969-5_14More infoMortality rates from colorectal cancers (CRC) have been declining due to advances in screening and diagnostic technology. However, they remain the third most common cancer diagnosis and fourth leading cause of cancer-related mortality worldwide.
- Romagnolo, D. F., & Selmin, O. I. (2016). Mediterranean Diet and Lifestyle in a Modern World Context. In Mediterranean Diet. Humana Press, Cham. doi:10.1007/978-3-319-27969-5_2More infoNutrition and lifestyle have been shown to impact the etiology of major causes of death including heart, malignant neoplasms, chronic lower respiratory, cerebrovascular, Alzheimer’s, and diabetes diseases. The death incidence attributable to these causes is projected to increase due to the growing and aging population. Socioeconomic constraints contribute to the coexistence of non-communicable diseases with food insecurity.
- Romagnolo, D. F., Jackson, K. A., Jackson, K. A., Sparks, P. L., Sparks, P. L., & Selmin, O. I. (2016). Building the Mediterranean Pyramid: Part B—Balancing the Plate. In Mediterranean diet. Humana Press, Cham. doi:10.1007/978-3-319-27969-5_20More infoThe traditional Mediterranean diet finds its roots in the diverse cultures and traditions of the countries bordering the Mediterranean Sea. Foundational elements of the Mediterranean pyramid can be found in those of the 1960’ in Crete, much of Greece and Southern Italy.
- Selmin, O. I., & Romagnolo, D. F. (2016). Building the Mediterranean Pyramid: Part A—Mediterranean Recipes. In Mediterranean Diet(pp 261-273). Springer International Publishing. doi:10.1007/978-3-319-27969-5_19More infoIn this chapter, we provide a compilation of selected recipes from the Mediterranean region (PART A). For each recipe, we cataloged information on the ingredients, quantities, and preparation.
- Selmin, O. I., Romagnolo, A. P., & Romagnolo, D. F. (2016). Mediterranean Diet and Neurodegenerative Diseases. In Mediterranean Diet. Humana Press, Cham. doi:10.1007/978-3-319-27969-5_12More infoCognitive decline, dementia, Alzheimer’s (AD) and Parkinson’s (PD) disease are age-related conditions that affect mature adults worldwide. Risk factors include hypercholesterolemia, obesity, diabetes, and cardiovascular factors, such as hypertension, and inflammation.
- Romagnolo, D. F., & Selmin, O. I. (2015). Epigenetics of Endocrine Tumors in Women and Dietary Prevention. In Preventive Nutrition(pp 153-166). Springer, Cham. doi:10.1007/978-3-319-22431-2_9More infoEndocrine tumors, primarily breast, followed by uterine, ovarian, and cervical cancer, are frequent malignancies in women (Fig. 9.1). The development of these tumors can be linked to activation of oncogenes whose protein products contribute to stimulation of cancer processes such as cell proliferation, inflammation, invasion, angiogenesis, and metastasis; and/or inactivation of tumor suppressor genes which oppose the function of oncogenes and encode for proteins that inhibit cell proliferation, regulate DNA repair, and induce apoptosis. According to the Knudson “two-hits” hypothesis, hereditary cancers result from inherited gene mutations (first hit) in one copy of a cancer susceptibility gene (Fig. 9.2a). This is also referred to as haploinsufficiency when a single-copy loss in a tumor suppressor gene is sufficient for promotion of cancer. The second allele (second hit) is usually inactivated somatically (loss of heterozygosity) during growth and development (http://www.cancer.org). Interestingly, only a small fraction (5–10 %) of cancers is linked to germline mutations of tumor suppressor genes and tends to occur early in life. Examples of tumor suppressor genes mutated in hereditary cancers are Rb, p53, Apc, BRCA-1, and BRCA-2. This scenario differs from that of sporadic tumors which represent the majority of tumors. They usually occur later in life in the context of other genetic and/or environmental insults (Nature 476:163–9, 2011) and when both alleles for a specific tumor suppressor gene are somatically inactivated. Therefore, understanding the mechanisms that lead to somatic inactivation of tumor suppressor genes provides rich opportunities for prevention of both hereditary and sporadic tumors including endocrine malignancies in women.
- Selmin, O. I., Runyan, R. B., & Makwana, O. (2014). Environmental Sensitivity to Trichloroethylene (TCE) in the Developing Heart. In Trichloroethylene: Toxicity and Health Risks(pp 153-169). London: Springer.
- Romagnolo, D. F., & Selmin, O. I. (2013). Herbal Supplements in the Prevention and Treatment of Cancer. In Handbook of Nutrition and Food. Routledge Handbooks Online. doi:10.1201/B15294-49
- Romagnolo, D. F., Degner, S. C., & Selmin, O. I. (2010). Aryl Hydrocarbon Receptor-Mediated Carcinogenesis and Modulation by Dietary Xenobiotic and Natural Ligands. In Bioactive compounds and cancer(pp 761-782). Humana Press, Totowa, NJ. doi:10.1007/978-1-60761-627-6_32More info1. The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor of the helix-loop-helix/PAS family. Many compounds interact with the AhR including xenobiotic (“xeno” = foreign) polycyclic aromatic hydrocarbons (PAH) and dioxins, endogenous ligands, and natural bioactive compounds. The activation of the AhR leads to increased expression of Phase I enzymes at xenobiotic responsive elements (XRE) and production of chemically reactive species known to induce cancer. Conversely, activation of the AhR leads to decreased expression of the tumor-suppressor genes p16 and BRCA-1.
Journals/Publications
- Chen, S., Lencinas, A., Nunez, M., Selmin, O., & Runyan, R. B. (2017). HNF4a transcription is a target of trichloroethylene toxicity in the embryonic mouse heart. Reproductive Toxicology.More infoHepatocyte Nuclear Factor 4 alpha (HNF4a), is a target of trichloroethylene (TCE) exposure in the chick heart. As the chick embryo is non-placental and without maternal metabolism, experiments were pursued to explore HNF4a in the mouse. Benfluorex and Bi6015, agonists and antagonists of HNF4a respectively, were compared with low dose TCE exposure. Both reagents inhibited expression of TCE-sensitive genes at 5µM in HFN4a-expressing HepG2 cells. Pregnant mice were exposed to 10ppb (76 nM) TCE, 5µM Benfuorex, 5µM Bi6015, or Bi6015 and TCE in drinking water. Litters (E12) were collected and hearts were extracted for RNA and marker genes were examined by quantitative PCR. Markers, identified as sensitive to TCE exposure in chicks or as established targets of HNF4a transcription, were significantly affected by Benfluorex and Bi6015. Intersection of activity between TCE and HNF4a-specific reagents on marker expression argues that HNF4a is a significant component of TCE cardio-toxicity in placental mammals.
- Runyan, R. B., Selmin, O., Nunez, M., Lencinas, A., & Chen, S. (2020). HNF4a transcription is a target of trichloroethylene toxicity in the embryonic mouse heart. Environmental Science: Processes & Impacts.More infoPaper was submitted as a contribution to a special issue of ESPI (UK Royal Society of Chemistry) on halogenated solvents
- Selmin, O. (2017). Epigenetic regulation of FXR by a high fat diet rich in linoleic acid in mouse colonic mucosa. Molecular Nutrition and Food Research.
- Selmin, O. (2018). Conditional AhR knockout reverses in utero-mediated BRCA1CpG methylation and amplifies expression of estrogen and progesterone receptor in mammary tissue of female mouse offspring.. BMC.
- Selmin, O. (2018). Special Issue on Breast Cancer and Nutrition. Frontiers in Clinical Nutrition.
- Selmin, O. (2020). A comprehensive investigation into the potential utility of dietary aryl hydrocarbon receptor antagonists for primary prevention of breast cancer.. Breast cancer and Nutrition.
- Selmin, O. (2020). Characterization of a FXR transgene and effect on n-6 high-fat diet-induced colitis. International Journal of Molecular Science.
- Selmin, O. (2020). Epigenetic regulation and dietary control of Triple Negative Breast Cancer. Frontiers Nutrition.
- Selmin, O. (2020). Mediterranean diet for the prevention of ER-negative breast cancers: Molecular interactions of olive oil and vegetable bioactives in HER2-enriched and triple negative breast cancers. Molecular Nutrition: Cancer.
- Wren, S. N., Snider, J. M., Snider, A. J., Smith, C., Selmin, O. I., Romagnolo, D. F., Papoutsis, A. J., Hazan, S., Greenfield, N., Donovan, M. G., Doetschman, T. C., & Chow, S. H. (2021). n-6 High Fat Diet Induces Gut Microbiome Dysbiosis and Colonic Inflammation.. International journal of molecular sciences, 22(13). doi:10.3390/ijms22136919More infoBackground: Concerns are emerging that a high-fat diet rich in n-6 PUFA (n-6HFD) may alter gut microbiome and increase the risk of intestinal disorders. Research is needed to model the relationships between consumption of an n-6HFD starting at weaning and development of gut dysbiosis and colonic inflammation in adulthood. We used a C57BL/6J mouse model to compare the effects of exposure to a typical American Western diet (WD) providing 58.4%, 27.8%, and 13.7% energy (%E) from carbohydrates, fat, and protein, respectively, with those of an isocaloric and isoproteic soybean oil-rich n-6HFD providing 50%E and 35.9%E from total fat and carbohydrates, respectively on gut inflammation and microbiome profile. Methods: At weaning, male offspring were assigned to either the WD or n-6HFD through 10-16 weeks of age. The WD included fat exclusively from palm oil whereas the n-6HFD contained fat exclusively from soybean oil. We recorded changes in body weight, cyclooxygenase-2 (COX-2) expression, colon histopathology, and gut microbiome profile. Results: Compared to the WD, the n-6HFD increased plasma levels of n-6 fatty acids; colonic expression of COX-2; and the number of colonic inflammatory and hyperplastic lesions. At 16 weeks of age, the n-6HFD caused a marked reduction in the gut presence of Firmicutes, Clostridia, and Lachnospiraceae, and induced growth of Bacteroidetes and Deferribacteraceae. At the species level, the n-6HFD sustains the gut growth of proinflammatory Mucispirillum schaedleri and Lactobacillus murinus. Conclusions: An n-6HFD consumed from weaning to adulthood induces a shift in gut bacterial profile associated with colonic inflammation.
- Donovan, M. G., Stillwater, B. J., Selmin, O. I., Romagnolo, D. F., Neumayer, L. A., Donovan, M. G., & Bull, A. C. (2020). Bisphenols and Risk of Breast Cancer: A Narrative Review of the Impact of Diet and Bioactive Food Components.. Frontiers in nutrition, 7, 581388. doi:10.3389/fnut.2020.581388More infoData from preclinical studies suggest a link between increased risk of breast cancer and exposure to bisphenols at doses below what the United States Food and Drug Administration (FDA) considers as safe for consumption. Bisphenols exert estrogenic effects and are found in canned and plastic wrapped foods, food packaging, and plasticware. Mechanistically, bisphenols bind to the estrogen receptor (ER) and activate the expression of genes associated with cell proliferation and breast cancer. In this paper, we present a narrative literature review addressing bisphenol A and chemical analogs including bisphenol AF, bisphenol F, and bisphenol S selected as prototype xenoestrogens; then, we discuss biological mechanisms of action of these bisphenols in breast cells and potential impact of exposure at different stages of development (i.e., perinatal, peripubertal, and adult). Finally, we summarize studies detailing interactions, both preventative and promoting, of bisphenols with food components on breast cancer risk. We conclude the review with a discussion of current controversies in interpretation of the above research and future areas for investigation, including the impact of bisphenols and food components on breast tumor risk.
- Donovan, M. G., Wren, S. N., Selmin, O. I., Romagnolo, D. F., Donovan, M. G., & Cenker, M. (2020). Dietary fat and obesity as modulators of breast cancer risk: Focus on DNA methylation.. British journal of pharmacology, 177(6), 1331-1350. doi:10.1111/bph.14891More infoBreast cancer (BC) is the most common cancer and second leading cause of cancer mortality in women worldwide. Validated biomarkers enhance efforts for early detection and treatment, which reduce the risk of mortality. Epigenetic signatures have been suggested as good biomarkers for early detection, prognosis and targeted therapy of BC. Here, we highlight studies documenting the modifying effects of dietary fatty acids and obesity on BC biomarkers associated with DNA methylation. We focus our analysis on changes elicited in writers of DNA methylation (i.e., DNA methyltransferases), global DNA methylation and gene-specific DNA methylation. To provide context, we precede this discussion with a review of the available evidence for an association between BC incidence and both dietary fat consumption and obesity. We also include a review of well-vetted BC biomarkers related to cytosine-guanine dinucleotides methylation and how they influence BC risk, prognosis, tumour characteristics and response to treatment. LINKED ARTICLES: This article is part of a themed section on The Pharmacology of Nutraceuticals. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.6/issuetoc.
- Neumayer, L. A., Donovan, M. G., Stillwater, B. J., Selmin, O. I., Romagnolo, D. F., Neumayer, L. A., & Donovan, M. G. (2020). Do Olive and Fish Oils of the Mediterranean Diet Have a Role in Triple Negative Breast Cancer Prevention and Therapy? An Exploration of Evidence in Cells and Animal Models.. Frontiers in nutrition, 7, 571455. doi:10.3389/fnut.2020.571455More infoBreast cancer is the most common malignancy and cause of cancer-related mortality among women worldwide. Triple negative breast cancers (TNBC) are the most aggressive and lethal of the breast cancer molecular subtypes, due in part to a poor understanding of TNBC etiology and lack of targeted therapeutics. Despite advances in the clinical management of TNBC, optimal treatment regimens remain elusive. Thus, identifying interventional approaches that suppress the initiation and progression of TNBC, while minimizing side effects, would be of great interest. Studies have documented an inverse relationship between the incidence of hormone receptor negative breast cancer and adherence to a Mediterranean Diet, particularly higher consumption of fish and olive oil. Here, we performed a review of studies over the last 5 years investigating the effects of fish oil, olive oil and their components in model systems of TNBC. We included studies that focused on the fish oil ω-3 essential fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) in addition to olive oil polyphenolic compounds and oleic acid. Both beneficial and deleterious effects on TNBC model systems are reviewed and we highlight how multiple components of these Mediterranean Diet oils target signaling pathways known to be aberrant in TNBC including PI3K/Akt/mTOR, NF-κB/COX2 and Wnt/β-catenin.
- Donovan, M. G., Selmin, O. I., Romagnolo, D. F., Donovan, M. G., & Doetschman, T. (2019). Abstract 1604: Modulating effects of genistein in a mouse model of conditionalBRCA1deletion and triple negative breast cancer cells. Cancer Research. doi:10.1158/1538-7445.sabcs18-1604
- Donovan, M. G., Wren, S. N., Selmin, O. I., Romagnolo, D. F., Donovan, M. G., & Doetschman, T. (2019). Development and Characterization of a Mouse Model Overexpressing a Farnesoid-X-Receptor Transgene with Reduced Markers of Intestinal Inflammation (P08-122-19). Current Developments in Nutrition, 3(Supplement_1). doi:10.1093/cdn/nzz044.p08-122-19More infoAbstract Objectives The farnesoid-X-receptor (FXR) regulates bile acid (BA) homeostasis, protecting against colonic inflammation and cancer. Conversely, increased intestinal levels of BA and expression of cyclooxygenase-2 (COX-2) increase the risk of inflammation and cancer of the colon. Earlier studies from our laboratory show that a diet rich in n-6 linoleic acid (n-6HFD) epigenetically activates Fxr, inducing the expression of downstream factors that regulate BA homeostasis. However, the chronic exposure to n-6HFD induces COX-2 expression through CpG demethylation of the PTSG-2 gene and activates the β-catenin pathway. The objective of this study is to determine in a mouse and cell culture models the influence of an n-6HFD on endpoints of intestinal inflammation and the modifying effects of overexpression of FXR. Methods A mouse line overexpressing FXR in the intestine was developed by injecting an FXRtransgene (FxrTG) construct driven by the villin promoter into FVB zygotes, and then crossed with C57BL6 mice. The small intestine and colon tissue were collected from male founders. Changes in gene expression and DNA methylation were measured by real-time PCR (RT-PCR). Cell culture experiments were performed in colonic human fetal cell (FHC) cells treated with linoleic acid (LA). Results Expression analyses by RT-PCR reveal increased expression of FxrTG in distal small intestine and proximal and distal colon. These changes are paralleled by accumulation of ileal bile acid-binding protein (IBABP) and small heterodimer partner (SHP), two downstream targets of FXR, and a reduction in expression of COX-2. Western blot of colon FHC shows LA induces expression of COX-2. Conclusions We conclude that increased expression of FXR triggers the expression of genes involved in BA homeostasis and downregulates genes involved in inflammation. The FxrTG mouse model is being used to investigate the modifying effects of diets varying in fatty acid level and profile on endpoints of intestinal inflammation and cancer. Funding Sources This work was supported by a grant from NIFA, GRANT12445471, and a predoctoral training grant to M.G.D. from the Cancer Biology Training Grant T32CA009213.
- Selmin, O. (2019). Arsenic-induced BRCA1 CpG promoter methylation is associated with the downregulation of ERα and resistance to tamoxifen in MCF7 breast cancer cells and mouse mammary tumor xenografts. International Journal of Oncology.
- Selmin, O. (2019). Dietary fat and obesity as modulators of BC risk: Focus on DNA methylation.. British Journal of Pharmacology. doi:doi: 10.1111/bph.14891.
- Selmin, O. (2019). Epigenetic Activation of BRCA1 by Genistein In Vivo and Triple Negative Breast Cancer Cells Linked to Antagonism toward Aryl Hydrocarbon Receptor. Nutrients, 11(11).
- Selmin, O. (2019). n-6 Linoleic Acid Induces Epigenetics Alterations Associated with Colonic Inflammation and Cancer.. Nutrients, 11(1).
- Selmin, O. (2018). Arsenic-induced BRCA1 CpG promoter methylation associates with down regulation of ERalpha and resistance to tamoxifen... International Journal of Oncology.
- Selmin, O. (2018). Aryl Hydrocarbon Receptor Diet and Breast Cancer Risk. The Yale Journal of Biology and Medicine.
- Selmin, O. (2018). n-6 linoleic acid induces epigenetic alterations associated with colonic inflammation and cancer. Nutrients.
- Selmin, O. (2017). Genistein reverses BRCA-1 CpG methylation in human breast cancer cells with activated AhR. Current Developments in Nutrition.
- Selmin, O. (2017). Prevention by food bioactives in relation to breast cancer subtype: Epigenetic mechanisms.. Epigenetics of Chemoprevention. Elsevier.
- Selmin, O. I. (2017). Mediterranean Diet: Prevention of Inflammatory Bowel Disease and Colorectal Cancer. Frontiers in Nutrition, 4, 59-65. doi:10.3389/fnut.2017.00059
- Selmin, O. I., & Romagnolo, D. F. (2017). Mediterranean Diet and Prevention of Chronic Diseases.. Nutrition today, 52(5), 208-222. doi:10.1097/nt.0000000000000228More infoA large body of research data suggests that traditional dietary habits and lifestyle unique to the Mediterranean region (Mediterranean diet, MD) lower the incidence of chronic diseases and improve longevity. These data contrast with troubling statistics in the United States and other high income countries pointing to an increase in the incidence of chronic diseases and the projected explosion in cost of medical care associated with an aging population. In 2013, the MD was inscribed by UNESCO in the "Representative List of the Intangible Cultural Heritage of Humanity." The 2015-2020 Dietary Guidelines for Americans included the MD as a healthy dietary pattern. Therefore, specific objectives of this article are to provide an overview of the nutritional basis of this healthful diet, its metabolic benefits, and its role in multiple aspects of disease prevention and healthy aging. Whereas recommendations about the MD often focus on specific foods or bioactive compounds, we suggest that the eating pattern as a whole likely contributes to the health promoting effects of the MD.
- Selmin, O. I., Romagnolo, D. F., & Papoutsis, A. J. (2016). Abstract 4318: Reversal of BRCA-1 CpG hyperthylation by genistein and (-)-epigallocatechin-3-gallate in human breast cancer cells with activated AhR. Cancer Research, 76, 4318-4318. doi:10.1158/1538-7445.am2016-4318More infoProceedings: AACR 107th Annual Meeting 2016; April 16-20, 2016; New Orleans, LA Sporadic breast cancers, which represent the vast majority (∼90%) of breast tumor cases, do not have mutations in the tumor suppressor gene, BRCA-1 but have absent or markedly reduced levels of BRCA-1 similar to those observed in hereditary BRCA-1 tumors. Therefore, understanding the non-mutational mechanisms that contribute to repression of BRCA-1 has important implications for the prevention of both hereditary and sporadic breast tumors. Agonists of the aromatic hydrocarbon receptor (AhR) are ubiquitous in the environment and include dietary compounds, metabolites of fatty acids, industrial pollution, and photoproducts generated in the skin from ultraviolet radiation. In cultured estrogen-receptor (ER)α-positive MCF-7 breast cancer cells, we found that activation of the AhR with the prototype ligand 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD) repressed by 50% estradiol-induced BRCA-1 expression. Conversely, the post-treatment with the soy isoflavone genistein and tea (-)-epigallocatechin-3-gallate (EGCG) at physiological doses (1 μM) rescued within 24 to 48 h BRCA-1 expression to levels ∼2.0 to 3.0-fold higher than those measured in cells treated with estradiol alone. Genistein and EGCG reversed BRCA-1 promoter hypermethylation in AhR-activated MCF-7 cells. In ERα-negative and AhR-overexpressing UACC-3199 breast cancer cells, genistein (1 μM) reactivated BRCA-1 expression. The post-treatment of AhR-activated MCF-7 cells with genistein and EGCG antagonized the recruitment of DNA-methyl transferase-1 (DNMT-1) enzyme to the BRCA-1 promoter. These results suggest the involvement of epigenetic mechanisms in the repression of BRCA-1 and reversal effects of genistein and EGCG against breast tumorigenesis associated with activation of the AhR. Citation Format: Ornella I. Selmin, Andreas J. Papoutsis, Donato F. Romagnolo. Reversal of BRCA-1 CpG hyperthylation by genistein and (-)-epigallocatechin-3-gallate in human breast cancer cells with activated AhR. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4318.
- Selmin, O. I., Romagnolo, D. F., & Papoutsis, A. J. (2016). Reversal Effects of Genistein and (−)-Epigallocatechin-3-Gallate on Repression of BRCA-1 Expression in Human Breast Cancer Cells with Activated AhR. The FASEB Journal, 30.More infoSporadic breast cancers, which represent the vast majority (~90%) of breast tumor cases, do not have mutations in the tumor suppressor gene, BRCA-1 but have absent or markedly reduced levels of BRC...
- Selmin, O. I., Romagnolo, D. F., Ramos, S. A., Propper, C. R., Grunwald, J. T., & Daniels, K. D. (2016). Epigenetics of breast cancer: Modifying role of environmental and bioactive food compounds.. Molecular nutrition & food research, 60(6), 1310-29. doi:10.1002/mnfr.201501063More infoReduced expression of tumor suppressor genes (TSG) increases the susceptibility to breast cancer. However, only a small percentage of breast tumors is related to family history and mutational inactivation of TSG. Epigenetics refers to non-mutational events that alter gene expression. Endocrine disruptors found in foods and drinking water may disrupt epigenetically hormonal regulation and increase breast cancer risk. This review centers on the working hypothesis that agonists of the aromatic hydrocarbon receptor (AHR), bisphenol A (BPA), and arsenic compounds, induce in TSG epigenetic signatures that mirror those often seen in sporadic breast tumors. Conversely, it is hypothesized that bioactive food components that target epigenetic mechanisms protect against sporadic breast cancer induced by these disruptors..This review highlights (i) overlaps between epigenetic signatures placed in TSG by AHR-ligands, BPA, and arsenic with epigenetic alterations associated with sporadic breast tumorigenesis; and (ii) potential opportunities for the prevention of sporadic breast cancer with food components that target the epigenetic machinery..Characterizing the overlap between epigenetic signatures elicited in TSG by endocrine disruptors with those observed in sporadic breast tumors may afford new strategies for breast cancer prevention with specific bioactive food components or diet.
- Thompson, P. A., Smith, J. W., Selmin, O. I., Romagnolo, D. F., Martinez, J. D., Lyon, A. M., Lance, P. M., Fang, C., & Doetschman, T. C. (2016). Inactivation of Adenomatous Polyposis Coli Reduces Bile Acid/Farnesoid X Receptor Expression through Fxr gene CpG Methylation in Mouse Colon Tumors and Human Colon Cancer Cells.. The Journal of nutrition, 146(2), 236-42. doi:10.3945/jn.115.216580More infoThe farnesoid X receptor (FXR) regulates bile acid (BA) metabolism and possesses tumor suppressor functions. FXR expression is reduced in colorectal tumors of subjects carrying inactivated adenomatous polyposis coli (APC). Identifying the mechanisms responsible for this reduction may offer new molecular targets for colon cancer prevention..We investigated how APC inactivation influences the regulation of FXR expression in colonic mucosal cells. We hypothesized that APC inactivation would epigenetically repress nuclear receptor subfamily 1, group H, member 4 (FXR gene name) expression through increased CpG methylation..Normal proximal colonic mucosa and normal-appearing adjacent colonic mucosa and colon tumors were collected from wild-type C57BL/6J and Apc-deficient (Apc(Min) (/+)) male mice, respectively. The expression of Fxr, ileal bile acid-binding protein (Ibabp), small heterodimer partner (Shp), and cyclooxygenase-2 (Cox-2) were determined by real-time polymerase chain reaction. In both normal and adjacent colonic mucosa and colon tumors, we measured CpG methylation of Fxr in bisulfonated genomic DNA. In vitro, we measured the impact of APC inactivation and deoxycholic acid (DCA) treatment on FXR expression in human colon cancer HCT-116 cells transfected with silencing RNA for APC and HT-29 cells carrying inactivated APC..In Apc(Min) (/+) mice, constitutive CpG methylation of the Fxrα3/4 promoter was linked to reduced (60-90%) baseline Fxr, Ibabp, and Shp and increased Cox-2 expression in apparently normal adjacent mucosa and colon tumors. Apc knockdown in HCT-116 cells increased cellular myelocytomatosis (c-MYC) and lowered (∼50%) FXR expression, which was further reduced (∼80%) by DCA. In human HCT-116 but not HT-29 colon cancer cells, DCA induced FXR expression and lowered CpG methylation of FXR..We conclude that the loss of APC function favors the silencing of FXR expression through CpG hypermethylation in mouse colonic mucosa and human colon cells, leading to reduced expression of downstream targets (SHP, IBABP) involved in BA homeostasis while increasing the expression of factors (COX-2, c-MYC) that contribute to inflammation and colon cancer.
- Runyan, R. B., Selmin, O. I., Lencinas, A., Nunez, M., Ismail, K. A., & Harris, A. P. (2018). Trichloroethylene perturbs HNF4a expression and activity in the developing chick heart. Toxicology Letters, 285(March 15), 113-120. doi:10.1016/j.toxlet.2017.12.027More infoExposure to trichloroethylene (TCE) is linked to formation of congenital heart defects in humans and animals. Prior interactome analysis identified the transcription factor, Hepatocyte Nuclear Factor 4 alpha (HNF4a), as a potential target of TCE exposure. As a role for HNF4a is unknown in the heart, we examined developing avian hearts for HNF4a expression and for sensitivity to TCE and the HNF4a agonist, Benfluorex. In vitro analysis using a HNF4a reporter construct showed both TCE and HFN4a to be antagonists of HNF4a-mediated transcription at the concentrations tested. HNF4a mRNA is expressed transiently in the embryonic heart during valve formation and cardiac development. Embryos were examined for altered gene expression in the presence of TCE or Benfluorex. TCE altered expression of selected mRNAs including HNF4a, TRAF6 and CYP2C45. There was a transition between inhibition and induction of marker gene expression in embryos as TCE concentration increased. Benfluorex was largely inhibitory to selected markers. Echocardiography of exposed embryos showed reduced cardiac function with both TCE and Benfluorex. Cardiac contraction was reduced by 29% and 23%, respectively at 10 ppb. The effects of TCE and Benfluorex on autocrine regulation of HNF4a, selected markers and cardiac function argue for a functional interaction of TCE and HNF4a. Further, the dose-sensitive shift between inhibition and induction of marker expression may explain the nonmonotonic-like dose response observed with TCE exposure in the heart.
- Selmin, O. I., Romagnolo, D. F., & Romagnolo, A. P. (2015). BRCA1 as target for breast cancer prevention and therapy.. Anti-cancer agents in medicinal chemistry, 15(1), 4-14. doi:10.2174/1871520614666141020153543More infoThe Breast Cancer 1 protein (BRCA1) is a tumor suppressor involved in basic cellular functions necessary for cell replication and DNA synthesis, but reduced expression of BRCA1, due to mutations or epigenetic inactivation, leads to impaired mammary gland differentiation and increased risk of breast cancer development. Although BRCA1 acts as a tumor suppressor and is present in all cells, where it is essential for the maintenance of the genome integrity, it is still not clear why mutations in the BRCA1 gene predispose to breast and ovarian, but not to other types of cancer. In the first part of this review, we briefly discuss the function and regulation of the BRCA1 protein, including its role associated with familial and sporadic breast cancer. The second part is an overview of the therapeutic compounds used for breast cancer treatment targeting BRCA1, and the natural food components that hold potential preventive effect against those types of breast cancer in which BRCA1 expression is either reduced or lacking. Further studies elucidating the interactions between dietary compounds and cellular pathways, involved in regulation of BRCA1expression, are necessary for the development of strategies that may successfully prevent or treat breast cancer.
- Selmin, O. I., Romagnolo, D. F., Papoutsis, A. J., & Borg, J. L. (2015). Gestational exposure to the AhR agonist 2,3,7,8-tetrachlorodibenzo-p-dioxin induces BRCA-1 promoter hypermethylation and reduces BRCA-1 expression in mammary tissue of rat offspring: preventive effects of resveratrol.. Molecular carcinogenesis, 54(4), 261-9. doi:10.1002/mc.22095More infoStudies with murine models suggest that maternal exposure to aromatic hydrocarbon receptor (AhR) agonists may impair mammary gland differentiation and increase the susceptibility to mammary carcinogenesis in offspring. However, the molecular mechanisms responsible for these perturbations remain largely unknown. Previously, we reported that the AhR agonists 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induced CpG methylation of the breast cancer-1 (BRCA-1) gene and reduced BRCA-1 expression in breast cancer cell lines. Based on the information both the human and rat BRCA-1 genes harbor xenobiotic responsive elements (XRE = 5'-GCGTG-3'), which are binding targets for the AhR, we extended our studies to the analysis of offspring of pregnant Sprague-Dawley rats treated during gestation with TCDD alone or in combination with the dietary AhR antagonist resveratrol (Res). We report that the in utero exposure to TCDD increased the number of terminal end buds (TEB) and reduced BRCA-1 expression in mammary tissue of offspring. The treatment with TCDD induced occupancy of the BRCA-1 promoter by DNA methyltransferase-1 (DNMT-1), CpG methylation of the BRCA-1 promoter, and expression of cyclin D1 and cyclin-dependent kinase-4 (CDK4). These changes were partially overridden by pre-exposure to Res, which stimulated the expression of the AhR repressor (AhRR) and its recruitment to the BRCA-1 gene. These findings point to maternal exposure to AhR agonists as a risk factor for breast cancer in offspring through epigenetic inhibition of BRCA-1 expression, whereas dietary antagonists of the AhR may exert protective effects.
- Selmin, O. I., Romagnolo, D. F., Papoutsis, A. J., & Laukaitis, C. M. (2015). Constitutive expression of AhR and BRCA-1 promoter CpG hypermethylation as biomarkers of ERα-negative breast tumorigenesis.. BMC cancer, 15(1), 1026. doi:10.1186/s12885-015-2044-9More infoOnly 5-10% of breast cancer cases is linked to germline mutations in the BRCA-1 gene and occurs early in life. Conversely, sporadic breast tumors, which represent 90-95% of breast malignancies, have lower BRCA-1 expression, but not mutated BRCA-1 gene, and tend to occur later in life in combination with other genetic alterations and/or environmental exposures. The latter may include environmental and dietary factors that activate the aromatic hydrocarbon receptor (AhR). Therefore, understanding if changes in expression and/or activation of the AhR are associated with somatic inactivation of the BRCA-1 gene may provide clues for breast cancer therapy..We evaluated Brca-1 CpG promoter methylation and expression in mammary tumors induced in Sprague-Dawley rats with the AhR agonist and mammary carcinogen 7,12-dimethyl-benzo(a)anthracene (DMBA). Also, we tested in human estrogen receptor (ER)α-negative sporadic UACC-3199 and ERα-positive MCF-7 breast cancer cells carrying respectively, hyper- and hypomethylated BRCA-1 gene, if the treatment with the AhR antagonist α-naphthoflavone (αNF) modulated BRCA-1 and ERα expression. Finally, we examined the association between expression of AhR and BRCA-1 promoter CpG methylation in human triple-negative (TNBC), luminal-A (LUM-A), LUM-B, and epidermal growth factor receptor-2 (HER-2)-positive breast tumor samples..Mammary tumors induced with DMBA had reduced BRCA-1 and ERα expression; higher Brca-1 promoter CpG methylation; increased expression of Ahr and its downstream target Cyp1b1; and higher proliferation markers Ccnd1 (cyclin D1) and Cdk4. In human UACC-3199 cells, low BRCA-1 was paralleled by constitutive high AhR expression; the treatment with αNF rescued BRCA-1 and ERα, while enhancing preferential expression of CYP1A1 compared to CYP1B1. Conversely, in MCF-7 cells, αNF antagonized estradiol-dependent activation of BRCA-1 without effects on expression of ERα. TNBC exhibited increased basal AhR and BRCA-1 promoter CpG methylation compared to LUM-A, LUM-B, and HER-2-positive breast tumors..Constitutive AhR expression coupled to BRCA-1 promoter CpG hypermethylation may be predictive markers of ERα-negative breast tumor development. Regimens based on selected AhR modulators (SAhRMs) may be useful for therapy against ERα-negative tumors, and possibly, TNBC with increased AhR and hypermethylated BRCA-1 gene.
- Thompson, P. A., Smith, J. W., Selmin, O. I., Romagnolo, D. F., Martinez, J. D., Lyon, A. M., Lance, P. M., Fang, C., & Doetschman, T. C. (2015). Abstract 905: Influence of high fat diet and APC status on epigenetic regulation of FXR in colon cells. Cancer Research, 75, 905-905. doi:10.1158/1538-7445.am2015-905More infoBile acids (BAs) not recycled through the enterohepatic system can be modified in the colon into cancer-promoting secondary BAs such as deoxycholic acid (DCA). The farnesoid-X-receptor (FXR) regulates hepatic and intestinal BA homeostasis. However, in intestinal cells carrying defective adenomatous polyposis coli (Apc) gene the expression of FXR is reduced through yet unknown mechanisms. To investigate if Western high-fat diet (HFD) and Apc status influence epigenetic regulation of the Fxr in colonic mucosa. Weaned C57BL/6J male mice were fed a HFD (22% safflower oil = SO) or control low fat diet (LFD; 5% SO) for 6 wks. We examined the effects on CpG pmethylation of Fxr, and expression of FXR, peroxisome-proliferator activated receptor-gamma (PPARγ), and cyclooxygenase-2 (COX-2) mRNA. Also, we studied the influence of APC status on CpG methylation of the Fxr gene, and expression of FXR, ileal bile acid-binding protein (IBABP), small heterodimer partner (SHP), and COX-2 mRNA in normal colonic mucosa and colon tumors from APCMin/+ mice. Mice fed the HFD had reduced (60%) Fxr promoter methylation and increased (2∼3-fold) FXR, COX-2, and PPARγ mRNA levels. Conversely, APC-deficiency was associated with constitutive hypermethylation of the Fxr gene, elevation of COX-2, and reduced (60-90%) baseline FXR, IBABP, and SHP mRNA. In human HCT-116 colon cells, siRNA knock-down of APC reduced (50%) basal FXR mRNA expression, which was further reduced to 80% by DCA. We conclude that APC deficiency leads to constitutive epigenetic silencing of Fxr increasing the risk of inflammation and colon cancer associated with a Western HFD. Note: This abstract was not presented at the meeting. Citation Format: Ornella I. Selmin, Adam M. Lyon, Changming Fang, Tom C. Doetschman, Patricia A. Thompson, Jesse D. Martinez, Jeffrey Smith, Peter M. Lance, Donato F. Romagnolo. Influence of high fat diet and APC status on epigenetic regulation of FXR in colon cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 905. doi:10.1158/1538-7445.AM2015-905
- Thompson, P. A., Smith, J. W., Selmin, O. I., Romagnolo, D. F., Martinez, J. D., Lyon, A. M., Lance, P., Fang, C., & Doetschman, T. (2015). Epigenetic Regulation of the FXR by High Fat Diet and APC in Colon Cells. The FASEB Journal, 29. doi:10.1096/fasebj.29.1_supplement.394.2More infoThe farnesoid-X-receptor (FXR) controls hepatic and intestinal bile acid (BA) homeostasis. BAs not reabsorbed via the enterohepatic circulation are converted in the colon to deoxycholic acid (DCA) ...
- Zempleni, J., Selmin, O. I., & Romagnolo, D. F. (2014). Nuclear receptors and epigenetic regulation: opportunities for nutritional targeting and disease prevention.. Advances in nutrition (Bethesda, Md.), 5(4), 373-85. doi:10.3945/an.114.005868More infoPosttranslational modifications of histones, alterations in the recruitment and functions of non-histone proteins, DNA methylation, and changes in expression of noncoding RNAs contribute to current models of epigenetic regulation. Nuclear receptors (NRs) are a group of transcription factors that, through ligand-binding, act as sensors to changes in nutritional, environmental, developmental, pathophysiologic, and endocrine conditions and drive adaptive responses via gene regulation. One mechanism through which NRs direct gene expression is the assembly of transcription complexes with cofactors and coregulators that possess chromatin-modifying properties. Chromatin modifications can be transient or become part of the cellular "memory" and contribute to genomic imprinting. Because many food components bind to NRs, they can ultimately influence transcription of genes associated with biologic processes, such as inflammation, proliferation, apoptosis, and hormonal response, and alter the susceptibility to chronic diseases (e.g., cancer, diabetes, obesity). The objective of this review is to highlight how NRs influence epigenetic regulation and the relevance of dietary compound-NR interactions in human nutrition and for disease prevention and treatment. Identifying gene targets of unliganded and bound NRs may assist in the development of epigenetic maps for food components and dietary patterns. Progress in these areas may lead to the formulation of disease-prevention models based on epigenetic control by individual or associations of food ligands of NRs.
- Makwana, O., Ahles, L., Lencinas, A., Selmin, O. I., & Runyan, R. B. (2013). Low-dose trichloroethylene alters cytochrome P450-2C subfamily expression in the developing chick heart. Cardiovascular Toxicology, 13(1), 77-84.More infoPMID: 22855351;PMCID: PMC3927724;Abstract: Trichloroethylene (TCE) is an organic solvent and common environmental contaminant. TCE exposure is associated with heart defects in humans and animal models. Primary metabolism of TCE in adult rodent models is by specific hepatic cytochrome P450 enzymes (Lash et al. in Environ Health Perspect 108:177-200, 2000). As association of TCE exposure with cardiac defects is in exposed embryos prior to normal liver development, we investigated metabolism of TCE in the early embryo. Developing chick embryos were dosed in ovo with environmentally relevant doses of TCE (8 and 800 ppb) and RNA was extracted from cardiac and extra-cardiac tissue (whole embryo without heart). Real-time PCR showed upregulation of CYP2H1 transcripts in response to TCE exposure in the heart. No detectable cytochrome expression was found in extra-cardiac tissue. As seen previously, the dose response was non-monotonic and 8 ppb elicited stronger upregulation than 800 ppb. Immunostaining for CYP2C subfamily expression confirmed protein expression and showed localization in both myocardium and endothelium. TCE exposure increased protein expression in both tissues. These data demonstrate that the earliest embryonic expression of phase I detoxification enzymes is in the developing heart. Expression of these CYPs is likely to be relevant to the susceptibility of the developing heart to environmental teratogens. © 2012 Springer Science+Business Media, LLC.
- Selmin, O. I., & Romagnolo, D. F. (2012). Flavonoids and cancer prevention: a review of the evidence.. Journal of nutrition in gerontology and geriatrics, 31(3), 206-38. doi:10.1080/21551197.2012.702534More infoThe objective of this work is to review data from epidemiological and preclinical studies addressing the potential benefits of diets based on flavonoids for cancer prevention. Flavonoids are subdivided into subclasses including flavonols, flavones, flavanones, flavan-3-ols, anthocyanidins, and isoflavones. Epidemiological studies suggest dietary intake of flavonoids may reduce the risk of tumors of the breast, colon, lung, prostate, and pancreas. However, some studies have reported inconclusive or even harmful associations. A major challenge in the interpretation of epidemiological studies is that most of the data originate from case-control studies and retrospective acquisition of flavonoid intake. Differences in agricultural, sociodemographics, and lifestyle factors contribute to the heterogeneity in the intake of flavonoids among populations residing in the United States, Europe, and Asia. Dose and timing of exposure may influence the anticancer response to flavonoid-rich diets. A limited number of intervention trials of flavonoids have documented cancer preventative effects. Proposed anticancer mechanisms for flavonoids are inhibition of proliferation, inflammation, invasion, metastasis, and activation of apoptosis. Prospective studies with larger sample sizes are needed to develop biomarkers of flavonoid intake and effect. Mechanistic studies are needed to ascertain how flavonoid-rich diets influence gene regulation for cancer prevention.
- Selmin, O. I., Romagnolo, D. F., Papoutsis, A. J., & Borg, J. L. (2012). BRCA-1 promoter hypermethylation and silencing induced by the aromatic hydrocarbon receptor-ligand TCDD are prevented by resveratrol in MCF-7 cells.. The Journal of nutritional biochemistry, 23(10), 1324-32. doi:10.1016/j.jnutbio.2011.08.001More infoEpigenetic mechanisms may contribute to reduced expression of the tumor suppressor gene BRCA-1 in sporadic breast cancers. Through environmental exposure and diet, humans are exposed to xenobiotics and food compounds that bind the aromatic hydrocarbon receptor (AhR). AhR-ligands include the dioxin-like and tumor promoter 2,3,7,8 tetrachlorodibenzo-p-dioxin (TCDD). The activated AhR regulates transcription through binding to xenobiotic response elements (XREs=GCGTG) and interactions with transcription cofactors. Previously, we reported on the presence of several XREs in the proximal BRCA-1 promoter and that the expression of endogenous AhR was required for silencing of BRCA-1 expression by TCDD. Here, we document that in estrogen receptor-α-positive and BRCA-1 wild-type MCF-7 breast cancer cells, the treatment with TCDD attenuated 17β-estradiol-dependent stimulation of BRCA-1 protein and induced hypermethylation of a CpG island spanning the BRCA-1 transcriptional start site of exon-1a. Additionally, we found that TCDD enhanced the association of the AhR; DNA methyl transferase (DNMT)1, DNMT3a and DNMT3b; methyl binding protein (MBD)2; and trimethylated H3K9 (H3K9me3) with the BRCA-1 promoter. Conversely, the phytoalexin resveratrol, selected as a prototype dietary AhR antagonist, antagonized at physiologically relevant doses (1 μmol/L) the TCDD-induced repression of BRCA-1 protein, BRCA-1 promoter methylation and the recruitment of the AhR, MBD2, H3K9me3 and DNMTs (1, 3a and 3b). Taken together, these observations provide mechanistic evidence for AhR agonists in the establishment of BRCA-1 promoter hypermethylation and the basis for the development of prevention strategies based on AhR antagonists.
- Selmin, O. I., Romganolo, D., Papoutsis, A. J., & Borg, J. (2011). Resveratrol Prevents Epigenetic Silencing of BRCA-1 by the Activated AhR in Breast Cancer Cells. The FASEB Journal, 25.
- Selmin, O. I., Rowles, J., Romagnolo, D. F., Papoutsis, A. J., Palbykin, B., Caldwell, P. T., & Borg, J. (2011). Trichloroethylene induces methylation of the Serca2 promoter in H9c2 cells and embryonic heart.. Cardiovascular toxicology, 11(3), 204-14. doi:10.1007/s12012-011-9113-3More infoTrichloroethylene (TCE) is a halogenated hydrocarbon used as a solvent in industrial settings and in house-cleaning products. Exposure to TCE has been linked to increased risk for congenital heart malformations in both human and animal models. Previous studies showed TCE exposure reduced the expression and function of the ATP-dependent calcium pump, Serca2a, which is important for regulating calcium flux in myocytes and maintaining physiological cardiac function. In this study, we investigated whether TCE reduced Serca2a expression by altering the methylation status of its proximal promoter region. Low doses of TCE exposure (10 ppb) induced DNA hyper methylation in the Serca2 promoter region in cardiac myoblast cells and rat embryonic cardiac tissue. TCE exposure induced DNA methylation in a region of the Serca2 promoter which is the target for SP1 binding site essential for regulation of Serca2a transcriptional activity. Chromatin immunoprecipitation data confirmed that TCE exposure reduced the binding of SP1 to the Serca2 promoter region adjacent to the methylated CpG dimer. Finally, low-dose TCE exposure reduced the concentration of S-adenosyl-methionine in exposed cells and embryos. These cumulative data indicate that epigenetic mechanisms, including DNA methylation, may be important in mediating the teratogenic effects of TCE in embryonic heart.
- Caldwell, P. T., Manziello, A., Howard, J., Palbykin, B., Runyan, R. B., & Selmin, O. (2010). Gene expression profiling in the fetal cardiac tissue after folate and low-dose trichloroethylene exposure. Birth Defects Research Part A - Clinical and Molecular Teratology, 88(2), 111-127.More infoPMID: 19813261;Abstract: BACKGROUND: Previous studies show gene expression alterations in rat embryo hearts and cell lines that correspond to the cardio-teratogenic effects of trichloroethylene (TCE) in animal models. One potential mechanism of TCE teratogenicity may be through altered regulation of calcium homeostatic genes with a corresponding inhibition of cardiac function. It has been suggested that TCE may interfere with the folic acid/methylation pathway in liver and kidney and alter gene regulation by epigenetic mechanisms. According to this hypothesis, folate supplementation in the maternal diet should counteract TCE effects on gene expression in the embryonic heart. APPROACH: To identify transcriptional targets altered in the embryonic heart after exposure to TCE, and possible protective effects of folate, we used DNA microarray technology to profile gene expression in embryonic mouse hearts with maternal TCE exposure and dietary changes in maternal folate. RESULTS: Exposure to low doses of TCE (10 ppb) caused extensive alterations in transcripts encoding proteins involved in transport, ion channel, transcription, differentiation, cytoskeleton, cell cycle, and apoptosis. Exogenous folate did not offset the effects of TCE exposure on normal gene expression, and both high and low levels of folate produced additional significant changes in gene expression. CONCLUSIONS: A mechanism by which TCE induces a folate deficiency does not explain altered gene expression patterns in the embryonic mouse heart. The data further suggest that use of folate supplementation, in the presence of this toxin, may be detrimental and not protective of the developing embryo © 2009 Wiley-Liss, Inc.
- Makwana, O., M., N., Ahles, L., Selmin, O., Granzier, H. L., & Runyan, R. B. (2010). Exposure to low-dose trichloroethylene alters shear stress gene expression and function in the developing chick heart. Cardiovascular Toxicology, 10(2), 100-107.More infoPMID: 20186580;PMCID: PMC3069695;Abstract: Trichloroethylene is an organic solvent used as an industrial degreasing agent. Due to its widespread use and volatile nature, TCE is a common environmental contaminant. Trichloroethylene exposure has been implicated in the etiology of heart defects in human populations and animal models. Recent data suggest misregulation of Ca2+ homeostasis in H9c2 cardiomyocyte cell line after TCE exposure. We hypothesized that misregulation of Ca2+ homeostasis alters myocyte function and leads to changes in embryonic blood flow. In turn, changes in cardiac flow are known to cause cardiac malformations. To investigate this hypothesis, we dosed developing chick embryos in ovo with environmentally relevant doses of TCE (8 and 800 ppb). RNA was isolated from control and treated embryos at specific times in development for real-time PCR analysis of blood flow markers. Effects were observed on Endothelin-1 (ET-1), Nitric Oxide Synthase-3 (NOS-3) and Krüppel-like Factor 2 (KLF2) expression relative to TCE exposure and consistent with reduced flow. Further, we measured function in the developing heart after TCE exposure by isolating cardiomyocytes and measuring half-width of contraction and sarcomere lengths. These functional data showed a significant increase in half-width of contraction after TCE exposure. These data suggest that perturbation of cardiac function contributes to the etiology of congenital heart defects in TCE-exposed embryos. © Springer Science+Business Media, LLC 2010.
- Selmin, O. I., Romagnolo, D. F., & Papoutsis, A. J. (2010). Abstract 1115: Epigenetic regulation of BRCA-1 by xenobiotic and dietary ligands of the aryl hydrocarbon receptor. Cancer Research, 70, 1115-1115. doi:10.1158/1538-7445.am10-1115More infoProceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC Mutations of BRCA-1 account for only 5-10% of breast cancer cases, whereas sporadic breast tumors represent the remaining 90-95%. In sporadic breast cancers there is silencing of BRCA-1 in the absence of mutations. Factors contributing to this etiology may include environmental ligands of the aryl hydrocarbon receptor (AhR) such as dioxins (ex.2,3,7,8 tetrachlorodibenzene(p)dioxin, TCDD) and polycyclic aryl hydrocarbons (PAHs). Dietary ligands of the AhR with potential protective effects include the phytoalexin resveratrol found in grapes. In this study, we investigated the mechanisms responsible for repression of BRCA-1 expression by the activated AhR. The results of DNA binding studies in MCF-7 breast cancer cells documented that TCDD-induced the association of the AhR to xenobiotic responsive elements (XRE) harbored in the BRCA-1 promoter region. The cotreatment with resveratrol reduced AhR recruitment in a dose-dependent fashion, prevented the TCDD-dependent repression of BRCA-1 transcription and restored BRCA-1 protein expression. The treatment with TCDD induced the recruitment of histone deacetylase-1, DNA methyltransferase-1, methyl-binding protein-2, and reduced the association of acetylated histone-4 and acetylated histone-K9. These effects were abrogated by cotreatment with resveratrol. We propose that dietary antagonists of the AhR such as resveratrol may be useful in the prevention of epigenetic BRCA-1 silencing. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1115.
- Selmin, O. I., Romagnolo, D. F., & Papoutsis, A. J. (2010). Nutritional targeting of cyclooxygenase-2 for colon cancer prevention.. Inflammation & allergy drug targets, 9(3), 181-91. doi:10.2174/187152810792231922More infoFactors related to diet and life style have been identified as primary determinants in about 80% of colorectal cancers. Non-steroidal anti-inflammatory drugs (NSAID) and selective cyclooxygenase-2 (COX-2) inhibitors (COXIB) reduce the relative risk of colon cancer. To overcome systemic COX inhibition associated with NSAID and COXIB, there is a growing interest in developing alternative colon cancer prevention strategies using diet-based approaches that target COX-2. The transition from aberrant crypt foci (ACF) to colon cancer is a multiyear process providing opportunities for nutritional targeting of genes influencing the course of this disease process at early stages of development. The activation of the proinflammatory gene COX-2 and PG production in the colonic mucosa are recognized risk factors in colon cancer. Many natural food components may impact colon cancer risk by interfering with ligand-activated receptors, signal transduction pathways, and transcription factors involved in stimulation of COX-2 expression. In this review, we highlight key upstream features of signaling pathways and transcriptional control of the COX-2 gene and discuss opportunities for dietary modulation of COX-2 expression in gastro-intestinal cancers with special emphasis on prevention of colorectal tumors. Review of the experimental evidence suggests that dietary strategies based on specific or cocktails of bioactive food components as well nutritional-pharmacological combinations targeted to regulation of COX-2 expression and activity may prove useful in the prevention of colon cancer. An integrated approach may offer the advantage of combined higher efficacies. Future studies should investigate the efficacy of combinations of bioactive food compounds on epigenetic regulation of the COX-2 gene and characterize potential synergies and amplification effects resulting from the concomitant use of bioactive food components and COX-2 inhibitors.
- Wondrak, G. T., Selmin, O. I., Romagnolo, D. F., Papoutsis, A. J., & Lamore, S. D. (2010). Resveratrol prevents epigenetic silencing of BRCA-1 by the aromatic hydrocarbon receptor in human breast cancer cells.. The Journal of nutrition, 140(9), 1607-14. doi:10.3945/jn.110.123422More infoThe BRCA-1 protein is a tumor suppressor involved in repair of DNA damage. Epigenetic mechanisms contribute to its reduced expression in sporadic breast tumors. Through diet, humans are exposed to a complex mixture of xenobiotics and natural ligands of the aromatic hydrocarbon receptor (AhR), which contributes to the etiology of various types of cancers. The AhR binds xenobiotics, endogenous ligands, and many natural dietary bioactive compounds, including the phytoalexin resveratrol (Res). In estrogen receptor- alpha (ER alpha )-positive and BRCA-1 wild-type MCF-7 breast cancer cells, we investigated the influence of AhR activation with the agonist 2,3,7,8 tetrachlorobenzo(p)dioxin (TCDD) on epigenetic regulation of the BRCA-1 gene and the preventative effects of Res. We report that activation and recruitment of the AhR to the BRCA-1 promoter hampers 17 beta -estradiol (E2)-dependent stimulation of BRCA-1 transcription and protein levels. These inhibitory effects are paralleled by reduced occupancy of ER alpha , acetylated histone (AcH)-4, and AcH3K9. Conversely, the treatment with TCDD increases the association of mono-methylated-H3K9, DNA-methyltransferase-1 (DNMT1), and methyl-binding domain protein-2 with the BRCA-1 promoter and stimulates the accumulation of DNA strand breaks. The AhR-dependent repression of BRCA-1 expression is reversed by small interference for the AhR and DNMT1 or pretreatment with Res, which reduces TCDD-induced DNA strand breaks. These results support the hypothesis that epigenetic silencing of the BRCA-1 gene by the AhR is preventable with Res and provide the molecular basis for the development of dietary strategies based on natural AhR antagonists.
- Petrick, J. S., Blachere, F. M., Selmin, O., & Lantz, R. C. (2009). Inorganic arsenic as a developmental toxicant: In utero exposure and alterations in the developing rat lungs. Molecular Nutrition and Food Research, 53(5), 583-591.More infoPMID: 19072884;PMCID: PMC2882184;Abstract: In the present study, we characterize the toxic effects of in utero arsenic exposure on the developing lung. We hypothesize that in utero exposure to inorganic arsenic through maternal drinking water causes altered gene and protein expression in the developing lung, indicative of downstream molecular and functional changes. From conception to embryonic day 18, we exposed pregnant Sprague-Dawley rats to 500 ppb arsenic (as arsenite) via the drinking water. Subtracted cDNA libraries comparing control to arsenic exposed embryonic lungs were generated. In addition, a broad Western blot analysis was performed to identify altered protein expression. A total of 59 genes and 34 proteins were identified as being altered. Pathway mapping and analysis showed that cell motility was the process most affected. The most likely affected pathway was alteration in integrin signaling through the b-catenin pathway, altering c-myc. The present study shows that arsenic induces alterations in the developing lung. These data may be useful in the elucidation of molecular targets and biomarkers of arsenic exposure during lung development and may aid in understanding the etiology of arsenic induced adult respiratory disease and lung cancers. © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
- Selmin, O. I., Romagnolo, D. F., Papoutsis, A. J., & Degner, S. C. (2009). Targeting of aryl hydrocarbon receptor-mediated activation of cyclooxygenase-2 expression by the indole-3-carbinol metabolite 3,3'-diindolylmethane in breast cancer cells.. The Journal of nutrition, 139(1), 26-32. doi:10.3945/jn.108.099259More infoLigands of the aryl hydrocarbon receptor (AhR) include the environmental xenobiotic 2,3,7,8 tetrachlorodibenzo(p)dioxin (TCDD), polycyclic aryl hydrocarbons, and the dietary compounds 3, 3'-diindolylmethane (DIM), a condensation product of indol-3-carbinol found in Brassica vegetables, and the phytoalexin resveratrol (RES). The AhR and its cofactors regulate the expression of target genes at pentameric (GCGTG) xenobiotic responsive elements (XRE). Because the activation of cyclooxygenase-2 (COX-2) expression by AhR ligands may contribute to inflammation and tumorigenesis, we investigated the epigenetic regulation of the COX-2 gene by TCDD and the reversal effects of DIM in MCF-7 breast cancer cells. Results of DNA binding and chromatin immunoprecipitation (ChIP) studies documented that the treatment with TCDD induced the association of the AhR to XRE harbored in the COX-2 promoter and control CYP1A1 promoter oligonucleotides. The TCDD-induced binding of the AhR was reduced by small-interfering RNA for the AhR or the cotreatment with synthetic (3-methoxy-4-naphthoflavone) or dietary AhR antagonists (DIM, RES). In time course ChIP studies, TCDD induced the rapid (15 min) occupancy by the AhR, the histone acetyl transferase p300, and acetylated histone H4 (AcH4) at the COX-2 promoter. Conversely, the cotreatment of MCF-7 cells with DIM (10 micromol/L) abrogated the TCDD-induced recruitment of the AhR and AcH4 to the COX-2 promoter and the induction of COX-2 mRNA and protein levels. Taken together, these data suggest that naturally occurring modulators of the AhR such as DIM may be effective agents for dietary strategies against epigenetic activation of COX-2 expression by AhR agonists.
- Caldwell, P. T., Thorne, P. A., Johnson, P. D., Boitano, S., Runyan, R. B., & Selmin, O. (2008). Trichloroethylene disrupts cardiac gene expression and calcium homeostasis in rat myocytes. Toxicological Sciences, 104(1), 135-143.More infoPMID: 18411232;PMCID: PMC4001797;Abstract: We have been investigating the molecular mechanisms by which trichloroethylene (TCE) might induce cardiac malformations in the embryonic heart. Previous results indicated that TCE disrupted expression of genes encoding proteins involved in regulation of intracellular Ca2+, [Ca2+]i, in cardiac cells, including ryanodine receptor isoform 2 (Ryr2), and sarcoendoplasmatic reticulum Ca2+ ATPase, Serca2a. These observations are important in light of the notion that altered cardiac contractility can produce morphological defects. The hypothesis tested in this study is that the TCE-induced changes in gene expression of Ca2+-associated proteins resulted in altered Ca2+ flux regulation. We used real-time PCR and digital imaging microscopy to characterize effects of various doses of TCE on gene expression and Ca2+ response to vasopressin (VP) in rat cardiac H9c2 myocytes. We observed a reduction in Serca2a and Ryr2 expression at 12 and 48 h after exposure to TCE. In addition, we found significant differences in Ca2+ response to VP in cells treated with TCE doses as low as 10 parts per billion. Taken all together, our data strongly indicate that exposure to TCE disrupts the ability of myocytes to regulate cellular Ca2+ fluxes. Perturbation of calcium signaling alters cardiac cell physiology and signal transduction and may hint to morphogenetic consequences in the context of heart development. These results point to a novel area of TCE biology and, if confirmed in vivo, may help to explain the apparent cardio-specific toxicity of TCE exposure in the rodent embryo. © The Author 2008. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved.
- Selmin, O. I., Thorne, P. A., Caldwell, P. T., & Taylor, M. R. (2008). Trichloroethylene and trichloroacetic acid regulate calcium signaling pathways in murine embryonal carcinoma cells P19. Cardiovascular Toxicology, 8(2), 47-56.More infoPMID: 18437584;Abstract: Trichloroethylene (TCE) and its metabolite trichloroacetic acid (TCA) are ubiquitous environmental contaminants which have been regarded as risk factors for congenital heart malformations. An increasing body of evidence from in vivo and in vitro studies supports the notion that exposure to TCE and TCA may interfere with normal embryonic heart development. The expression of several genes coding for factors implicated in the regulation of cardiac development has been shown to be modified by TCE or TCA, but the molecular mechanisms that mediate these effects are still obscure. In this study, we investigated the global changes in gene expression caused by exposure of P19 embryonal carcinoma cells to TCE and TCA, and whether or not TCE and/or TCA influence the expression levels of genes encoding for proteins that regulate calcium fluxes in cardiac cells. We report that TCE and TCA disrupt the expression of genes involved in processes important during embryonic development suggesting that exposure to environmentally significant concentrations of TCE may have deleterious effects on specific stages of cardiac differentiation. © 2008 Humana Press.
- Thorne, P. A., Selmin, O. I., Romagnolo, D. F., Liu, W., Kemp, M. Q., & Kane, M. D. (2006). Induction of the transferrin receptor gene by benzo[a]pyrene in breast cancer MCF-7 cells: potential as a biomarker of PAH exposure.. Environmental and molecular mutagenesis, 47(7), 518-26. doi:10.1002/em.20221More infoPolycyclic aromatic hydrocarbons (PAHs) are widespread environmental DNA-damaging agents regarded as risk factors for human disease, including lung and breast cancer. The biotransformation of PAHs to carcinogenic metabolites is mediated by the aromatic hydrocarbon receptor (AhR), which activates transcription at xenobiotic responsive elements (XREs = 5'-GCGTG-3') found in the promoter regions of genes encoding for detoxifying enzymes, including CYP1A1 and CYP1B1. In this study, we wished to identify novel biomarkers that may be useful in monitoring critical carcinogenic events of the breast induced by PAHs. Using a GeneMAP CancerArray, we analyzed in breast cancer MCF-7 cells the temporal effects of the AhR agonist benzo[a]pyrene (B[a]P), which is a prototype PAH and known environmental carcinogen. Genes upregulated at least threefold by B[a]P and containing potential XREs within their promoter regions included CYP1A1, CYP1B1, paired box gene 3 (PAX3), cortactin (CTTN/EMS1), beta-2-microglobulin (B2M), and transferrin receptor (TfR). The stimulatory effects of B[a]P on expression of these genes were abrogated by cotreatment with the AhR antagonist flavonoid, alpha-napthoflavone (ANF). The TfR gene was selected for further analysis as its promoter region contains two potential XREs and its expression has been shown to be increased in breast cancer cells. Accumulation of TfR mRNA in B[a]P-treated cells was confirmed by quantitative real time PCR. Transient transfection studies indicated that the transcriptional activity of the TfR promoter was stimulated by B[a]P, whereas ANF counteracted this induction. These results indicate that the TfR gene may be a potential biomarker of PAH exposure.
- Thorne, P. A., Selmin, O. I., Romagnolo, D. F., Morgan, S. S., Kemp, M. Q., & Hockings, J. K. (2006). The ligand status of the aromatic hydrocarbon receptor modulates transcriptional activation of BRCA-1 promoter by estrogen.. Cancer research, 66(4), 2224-32. doi:10.1158/0008-5472.can-05-1619More infoIn sporadic breast cancers, BRCA-1 expression is down-regulated in the absence of mutations in the BRCA-1 gene. This suggests that disruption of BRCA-1 expression may contribute to the onset of mammary tumors. Environmental contaminants found in industrial pollution, tobacco smoke, and cooked foods include benzo(a)pyrene [B(a)P] and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), which have been shown to act as endocrine disruptors and tumor promoters. In previous studies, we documented that estrogen (E2) induced BRCA-1 transcription through the recruitment of an activator protein-1/estrogen receptor-alpha (ER alpha) complex to the proximal BRCA-1 promoter. Here, we report that activation of BRCA-1 transcription by E2 requires occupancy of the BRCA-1 promoter by the unliganded aromatic hydrocarbon receptor (AhR). The stimulatory effects of E2 on BRCA-1 transcription are counteracted by (a) cotreatment with the AhR antagonist 3'-methoxy-4'-nitroflavone; (b) transient expression in ER alpha-negative HeLa cells of ER alpha lacking the protein-binding domain for the AhR; and (c) mutation of two consensus xenobiotic-responsive elements (XRE, 5'-GCGTG-3') located upstream of the ER alpha-binding region. These results suggest that the physical interaction between the unliganded AhR and the liganded ER alpha plays a positive role in E2-dependent activation of BRCA-1 transcription. Conversely, we show that the AhR ligands B(a)P and TCDD abrogate E2-induced BRCA-1 promoter activity. The repressive effects of TCDD are paralleled by increased recruitment of the liganded AhR and HDAC1, reduced occupancy by p300, SRC-1, and diminished acetylation of H4 at the BRCA-1 promoter region flanking the XREs. We propose that the ligand status of the AhR modulates activation of the BRCA-1 promoter by estrogen.
- Johnson, P. D., Thorne, P. A., Selmin, O. I., Romagnolo, D. F., Johnson, P. D., & Blachere, F. M. (2005). Transcriptional activation of the membrane-bound progesterone receptor (mPR) by dioxin, in endocrine-responsive tissues.. Molecular reproduction and development, 70(2), 166-74. doi:10.1002/mrd.20090More infoWe originally identified the membrane-bound progesterone receptor (mPR) using a screening for genes differentially expressed in liver of rats exposed to dioxin. Recent findings have suggested a role for the mPR in sperm cells, ovary, and brain; however, its mechanisms of action are largely unknown. In this study, we examined the expression pattern of the mPR in liver of rats exposed to dioxin and identified possible mechanisms of its regulation. We observed that mPR expression was induced by dioxin, but was also dependent on the hormonal responsiveness of the tissue. In particular, in male, but not female liver, dioxin induced the expression of the mPR. However, in control, untreated female liver the level of mPR transcript was higher than in control males. Moreover, in breast cancer cells MCF-7 dioxin induced mPR expression. Promoter studies using the luciferase assay indicated that a fragment of approximately 350 bp of the mPR promoter was able to induce luciferase activity in the presence of dioxin, suggesting that the presumptive XREs sites contained in this mPR promoter region are responsive to dioxin. Analysis of mPR protein level confirmed the results observed at the RNA level, both in rat liver and MCF-7 cells. Taken together, these observations suggest the existence of a novel cross-talk between steroid and aromatic hydrocarbon receptors (AhR), and underline the importance of the mPR as a mediator of physiologic effects of the sex hormones.
- Selmin, O., Thorne, P. A., Caldwell, P. T., Johnson, P. D., & Runyan, R. B. (2005). Effects of trichloroethylene and its metabolite trichloroacetic acid on the expression of vimentin in the rat H9c2 cell line. Cell Biology and Toxicology, 21(2), 83-95.More infoPMID: 16142583;Abstract: Trichloroethylene (TCE) and its metabolite trichloroacetic acid (TCAA) are environmental contaminants with specific toxicity for the embryonic heart. In an effort to identify the cellular pathways disrupted by TCE and TCAA during heart development, we investigated their effects on expression of vimentin, a marker of cardiac differentiation. Previous studies had shown that the level of vimentin transcript was inhibited in rat embryonic heart after maternal exposure to TCE via drinking water. In the same study, maternal exposure to TCAA produced the opposite effect, inducing an increased level of vimentin mRNA. In this study, we selected an in vitro system, the rat cardiac myoblast cell line H9c2, to further characterize the molecular mechanisms used by TCE and TCAA to disrupt normal heart development. In particular, we investigated the effects of both toxicants on vimentin, at both the RNA and protein levels, using dose-response and time course curves. Our experimental findings indicate that vimentin expression is affected by TCE and TCAA in H9c2 cells similarly as in vivo. The work is significant because it provides a suitable in vitro model for studies looking at toxicant effects on myocardiac cells, and it suggests that vimentin is a good marker of TCE exposure in the embryonic heart. © Springer 2005.
- Collier, J. M., Selmin, O., Johnson, P. D., & Runyan, R. B. (2003). Trichloroethylene effects on gene expression during cardiac development. Birth Defects Research Part A - Clinical and Molecular Teratology, 67(7), 488-495.More infoPMID: 14565619;Abstract: BACKGROUND: Halogenated hydrocarbon exposure is associated with changes in gene expression in adult and embryonic tissue. Our study was undertaken to identify differentially expressed mRNA transcripts in embryonic hearts from Sprague-Dawley rats exposed to trichloroethylene (TCE) or potential bio-transformation products dichloroethylene (DCE) and trichloroacetic acid (TCAA). METHODS: cDNA subtractive hybridization was used to selectively amplify expressed mRNA obtained from control or halogenated hydrocarbon exposed rat embryos. The doses used were 1100 and 110 ppm (8300 and 830 μM) TCE, 110 and 11 ppm (1100 and 110 μM) DCE, and 27.3 and 2.75 mg/ml (100 and 10 mM) TCAA. Control animals were given distilled drinking water throughout the period of experiments. RESULTS: Sequencing of over 100 clones derived from halogenated hydrocarbon exposed groups resulted in identification of numerous differentially regulated gene sequences. Up-regulated transcripts identified include genes associated with stress response (Hsp 70) and homeostasis (several ribosomal proteins). Down-regulated transcripts include extracellular matrix components (GPI-p137 and vimentin) and Ca2+ responsive proteins (Serca-2 Ca2+-ATPase and β-catenin). Two possible markers for fetal TCE exposure were identified: Serca-2 Ca2+-ATPase and GPI-p137, a GPI-linked protein of unknown function. Differential regulation of expression of both markers by TCE was confirmed by dot blot analysis and semi-quantitative RT-PCR with levels of TCE exposure between 100 and 250 ppb (0.76 and 1.9 μM) sufficient to decrease expression. CONCLUSIONS: Sequences down-regulated with TCE exposure appear to be those associated with cellular housekeeping, cell adhesion, and developmental processes, while TCE exposure up-regulates expression of numerous stress response and homeostatic genes. © 2003 Wiley-Liss, Inc.
- Selmin, O. I., Schultz, E. U., Romagnolo, D. F., Jeffy, B. D., Gudas, J. M., & Bowden, G. T. (1999). Inhibition of BRCA-1 expression by benzo[a]pyrene and its diol epoxide.. Molecular carcinogenesis, 26(2), 100-18. doi:10.1002/(sici)1098-2744(199910)26:2<100::aid-mc5>3.0.co;2-1More infoThe objective of this study was to investigate whether polycyclic aromatic hydrocarbons (PAHs) contribute to the etiology of sporadic breast cancer by altering the expression of BRCA-1. Acute exposure to the PAH benzo[a]pyrene (B[a]P) inhibited in a time- and dose-dependent fashion cell proliferation and levels of BRCA-1 mRNA and protein in estrogen receptor (ER)-positive breast MCF-7 and ovarian BG-1 cancer cells. Moreover, the acute exposure to B[a]P abrogated estrogen induction of BRCA-1 in MCF-7 cells. The loss of BRCA-1 expression was prevented by the aromatic hydrocarbon receptor (AhR) antagonist alpha-naphthoflavone, suggesting participation of the AhR pathway. BRCA-1 exon 1a transcripts were downregulated by B[a]P faster than exon 1b mRNA was. Long-term exposure to B[a]P (40 nM for 15 mo) lowered BRCA-1 mRNA levels in subclones of MCF-7 and BG-1 cells, whereas expression of BRCA-1 in these clones was reverted to normal levels by washing out of B[a]P. The mechanisms of BRCA-1 repression by B[a]P were further investigated by examining the effects of the halogenated aryl hydrocarbon 2,3,7, 8-tetrachlorodibenzo-p-dioxin (TCDD) and the B[a]P metabolite 7r, 8t-dihydroxy-9t,10t-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE). While TCDD did not influence basal BRCA-1 mRNA and protein levels at any of the doses (from 10 nM to 1 microM) tested in this study, treatment with 50 nM BPDE drastically reduced BRCA-1 mRNA levels, indicating that metabolism of B[a]P to BPDE may contribute to downregulation of BRCA-1. Conversely, ER-negative breast MDA-MB-231 and HBL-100 cancer cells were refractory to treatment with B[a]P or TCDD and expressed constant levels of BRCA-1 mRNA and protein. We conclude that B[a]P may be a risk factor in the etiology of sporadic breast cancer.
- Helzlsouer, K. J., Selmin, O., Huang, H., Strickland, P. T., Hoffman, S., Alberg, A. J., Watson, M., Comstock, G. W., & Bell, D. (1998). Association between glutathione S-transferase M1, P1, and T1 genetic polymorphisms and development of breast cancer. Journal of the National Cancer Institute, 90(7), 512-518.More infoPMID: 9539246;Abstract: Background: Glutathione S-transferases (GSTs) are encoded by a superfamily of genes and play a role in the detoxification of potential carcinogens. In a nested case-control study, we investigated associations between genetic variability in specific GST genes (GSTM1, GSTT1, and GSTP1) and susceptibility to breast cancer. Methods: In 1989, a total of 32898 individuals donated blood samples to a research specimen bank established in Washington County, MD. Genotypes of blood specimen DNA were determined for 110 of 115 women with incident cases of breast cancer diagnosed during the period from 1990 through 1995 and up to 113 of 115 control subjects. Associations between specific genotypes and the development of breast cancer were examined by use of logistic regression to calculate odds ratios (ORs) and 95 % confidence intervals (CIs). Results: The GSTM1 homozygous null genotype was associated with an increased risk of developing breast cancer (OR = 2.10; 95 % CI = 1.22-3.64), principally due to an association with postmenopausal breast cancer (OR = 2.50; 95%CI = 1.34-4.65). For GSTP1, the data were suggestive of a trend of increasing risk with higher numbers of codon 105 valine alleles (compared with isoleucine alleles); a 1.97-fold increased risk of breast cancer (95% CI = 0.77-5.02) was associated with valine/valine homozygosity. The risk of breast cancer associated with the GSTT1 homozygous null genotype was 1.50 (95% CI = 0.76-2.95). The risk of breast cancer increased as the number of putative high-risk genotypes increased (P for trend
- Millikan, R. C., Pittman, G. S., Newman, B., Tse, C. J., Selmin, O., Rockhill, B., Savitz, D., Moorman, P. G., & Bell, D. A. (1998). Cigarette smoking, N-acetyltransferases 1 and 2, and breast cancer risk. Cancer Epidemiology Biomarkers and Prevention, 7(5), 371-378.More infoPMID: 9610785;Abstract: To examine the effects of smoking and N-acetylation genetics on breast cancer risk, we analyzed data from an ongoing, population-based, case- control study of invasive breast cancer in North Carolina. The study population consisted of 498 cases and 473 controls, with approximately equal numbers of African-American and white women, and women under the age of 50 and age 50 years or older. Among premenopausal women, there was no association between current smoking [odds ratio (OR), 0.9; 95% confidence interval (CI), 0.5-1.5] or past smoking (OR, 1.0; 95% CI, 0.6-1.6) and breast cancer risk. Among postmenopausal women, there was also no association with current smoking (OR, 1.2; 95% CI, 0.7-2.0); however, a small increase in risk was observed for past smoking (OR, 1.5; 95% CI, 1.0-2.4). For postmenopausal women who smoked in the past, ORs and 95% CIs were 3.4 (1.4-8.1) for smoking within the past 3 years, 3.0 (1.3-6.7) for smoking 4-9 years ago, and 0.6 (0.3-1.4) for smoking 10-19 years ago. Neither N-acetyltransferase 1 (NAT1) nor N-acetyltransferase 2 (NAT2) genotype alone was associated with increased breast cancer risk. There was little evidence for modification of smoking effects according to genotype, except among postmenopausal women. Among postmenopausal women, ORs for smoking within the past 3 years were greater for women with the NAT1*10 genotype (OR, 9.0; 95% CI, 1.9-41.8) than NAT1- non*10 (OR, 2.5; 95% CI, 0.9-7.2) and greater for NAT2-rapid genotype (OR, 7.4; 95% CI, 1.6-32.6) than NAT2-slow (OR, 2.8; 95% CI, 0.4-8.0). Future studies of NAT genotypes and breast cancer should investigate the effects of environmental tobacco smoke, diet, and other exposures.
- Lavigne, J. A., Helzlsouer, K. J., Huang, H., Strickland, P. T., Bell, D. A., Selmin, O., Watson, M. A., Hoffman, S., Comstock, G. W., & Yager, J. D. (1997). An association between the allele coding for a low activity variant of catechol-O-methyltransferase and the risk for breast cancer. Cancer Research, 57(24), 5493-5497.More infoPMID: 9407957;Abstract: Mounting evidence suggests that catechol metabolites of estradiol may contribute to the development of estrogen-induced cancers. O-Methylation, catalyzed by catechol-O-methyltransferase (COMT), inactivates catechol estrogens. COMT is polymorphic in the human population, with 25% of Caucasians being homozygous for a low activity allele of the enzyme (COMT(LL)). We hypothesized that low activity COMT may be a risk factor for human breast cancer and designed a PCR-based RFLP assay to determine COMT genotype in a cohort of 112 matched, nested case-control samples. In the total study population, the odds ratios for the association of breast cancer risk with COMT(HL) and COMT(LL) genotypes were 1.30 [confidence interval (CI), 0.66-2.58] and 1.45 (CI, 0.69-3.07), respectively. Postmenopausal COMT(LL) women had a greater than 2-fold increased risk of developing breast cancer [odds ratio (OR), 2.18; CI, 0.93-5.11]. The association of COMT(LL) with the development of postmenopausal breast cancer was stronger and statistically significant in those women with a body mass index >24.47 kg/m2 (OR, 3.58; CI, 1.07-11.98). When COMT(LL) was combined with either glutathione S-transferase (GST) M1 null or with GSTP1 Ile-105-Val/Val-105- Val (intermediate/low activity, respectively) genotypes, the risk for developing postmenopausal breast cancer was also significantly increased. Our findings suggest that the allele encoding low activity COMT may be an important contributor to the postmenopausal development of breast cancer in certain women.
- Selmin, O. I., Rutherford, C. L., & Peters-weigel, S. (1997). Temporal regulation of the Dictyostelium glycogen phosphorylase 2 gene.. Biochimica et biophysica acta, 1351(1-2), 111-25. doi:10.1016/s0167-4781(96)00182-0More infoThe product of the glycogen phosphorylase-2 gene in Dictyostelium functions to provide the glucose units that are used to construct the structural components of the terminal stage of development. In this report, we link a 1233 bp upstream gp2 fragment to a luciferase reporter gene in order to study the sequences that are involved in the temporal expression of the gene. Various deletions of the promoter-luciferase fusion were then transformed into Dictyostelium cells. All deletion constructs, from -1216 to -486 nucleotides from the translational start codon, showed the same temporal pattern of expression as the authentic gp2 gene, as well as similar luciferase activities. Removal of an additional 37 nucleotides resulted in nearly 100-fold decrease in activity, yet retained the normal temporal expression of luciferase. Analysis of DNA binding proteins with the gel shift assay revealed a stage-dependent pattern of proteins that bound to the gp2 promoter. A similar pattern of temporal expression of the binding proteins was observed with either the full-length probe or with oligonucleotide probes that contained sequences that were identified as putative regulatory sites. Likewise, the full-length and oligonucleotide probes demonstrated identical binding patterns during several steps of purification of the DNA binding proteins. SDS-PAGE and Southwestern blot analysis of a DNA-affinity purified fraction, identified a 23 kDa peptide as the binding protein.
- Walker, N. J., Vandenheuvel, J., Tritscher, A., Sutter, T. R., Selmin, O. I., Lucier, G. W., Gastel, J. A., Clark, G. C., & Bell, D. A. (1997). Isolation and characterization of a novel gene induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin in rat liver. Hepatology Research, 7(1), 73-73. doi:10.1016/s0928-4346(97)89848-9
- Selmin, O., Lucier, G. W., Clark, G. C., Tritscher, A. M., Heuvel, J. V., Gastel, J. A., Walker, N. J., Sutter, T. R., & Bell, D. A. (1996). Isolation and characterization of a novel gene induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin in rat liver. Carcinogenesis, 17(12), 2609-2615.More infoPMID: 9006096;Abstract: The differential display technique was used to identify genes whose expression was regulated by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Expression of a novel sequence was up-regulated in a dose-dependent fashion in liver of Sprague-Dawley male rats exposed to both chronic and acute treatment with TCDD, as measured by densitometry of Northern blot analyses (P < 0.01). A rapid amplification of cDNA ends (RACE) procedure was used to isolate a 1.8 kb cDNA from a rat liver cDNA preparation. This cloned cDNA, called 25-Dx, was sequenced and found to encode a peptide of 223 amino acids. In control rats, the 25-Dx gene was expressed at high levels in lung and liver. A hydrophobic domain of 14 residues followed by a proline-rich domain, both located in the N-terminal region, showed 71% homology with the transmembrane domain of the precursor for the interleukin-6 receptor and a conserved consensus sequence found in the cytokine/growth factor/prolactin receptor superfamily respectively.
- Selmin, O. I., & Romagnolo, D. F. (1994). Renovating Italian science.. Science (New York, N.Y.), 263(5154), 1669. doi:10.1126/science.8134828
- Sucic, J. F., Selmin, O. I., & Rutherford, C. L. (1993). Regulation of the Dictyostelium glycogen phosphorylase 2 gene by cyclic AMP.. Developmental genetics, 14(4), 313-22. doi:10.1002/dvg.1020140409More infoA crucial developmental event in the cellular slime mold, Dictyostelium discoideum, is glycogen degradation. The enzyme that catalyzes this degradation, glycogen phosphorylase 2 (gp-2), is developmentally regulated and cAMP appears to be involved in this regulation. We have examined several aspects of the cAMP regulation of gp-2. We show that addition of exogenous cAMP to aggregation competent amoebae induced the appearance of gp-2 mRNA. The induction of gp-2 mRNA occurred within 1 and 1.5 h after the initial exposure to cAMP. Exposure to exogenous cAMP concentrations as low as 1.0 microM could induce gp-2 mRNA. We also examined the molecular mechanism through which cAMP induction of gp-2 occurs. Induction of gp-2 appears to result from a mechanism that does not require intracellular cAMP signaling, and may occur directly through a cAMP binding protein without the requirement of any intracellular signalling. We also examined the promoter region of the gp-2 gene for cis-acting elements that are involved in the cAMP regulation of gp-2. A series of deletions of the promoter were fused to a luciferase reporter gene and then analyzed for cAMP responsiveness. The results indicated that a region from -258 nucleotides to the transcriptional start site is sufficient for essentially full activity and appears to carry all necessary cis-acting sites for cAMP induction. Further deletion of 58 nucleotides from the 5' end, results in fivefold less activity in the presence of cAMP. Deletion of the next 104 nucleotides eliminates the cAMP response entirely.
- Yin, Y., Sucic, J. F., Selmin, O. I., Rutherford, C. L., Rogers, P. V., Peery, R. B., & Luo, S. (1992). Cloning, structural analysis, and expression of the glycogen phosphorylase-2 gene in Dictyostelium.. Journal of Biological Chemistry, 267(4), 2294-2302. doi:10.1016/s0021-9258(18)45877-2More infoThe glycogen phosphorylase-2 (GP2) activity that appears during the cell differentiation of Dictyostelium was purified to homogeneity. The molecular weight of the nondenatured enzyme was 200,000 as determined by Sephacryl S-300 gel filtration and was 107,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, suggesting that the native enzyme consists of two similar subunits. The intact protein was digested with trypsin and protease V8, and the resulting peptides were purified by microbore high pressure liquid chromatography. The peptides were sequenced, and oligonucleotides were constructed for polymerase chain reaction amplification of the GP2 gene from Dictyostelium genomic DNA template. The resulting polymerase chain reaction products were sequenced directly and were confirmed to encode portions of the GP2 gene. These fragments were used to probe a partial EcoRI genomic library for the remainder of the GP2 gene. The nucleotide sequence of the GP2-selected clones revealed an open reading frame of 2975 base pairs that was interrupted by two introns of 109 and 105 base pairs, respectively. The open reading frame encoded a protein of 992 amino acids with a calculated molecular mass of 112,500 Da and an isoelectric point of 6.4. An unusual sequence within the second exon of GP2, in which the triplet CAA was repeated 11 times, resulted in 11 in-frame glutamine residues of a possible 15 amino acids coded for by this region. The CAA repeat was transcribed, as shown by the sequence of cDNA. Comparison of the amino acid sequence of Dictyostelium GP2 to the phosphorylases from other organisms revealed that the Dictyostelium protein was 50 and 44% identical to yeast and rabbit muscle phosphorylases, respectively. Northern blot analysis showed that GP2 mRNA was absent in amebas and the early stages of development, reached a maximum level of expression at the slug stage, and then decreased in the terminal stages of development. Comparison of the mRNA expression with the appearance of GP2 enzyme protein and enzyme activity revealed that gp2 mRNA and a 113-kDa GP2 enzyme peptide were expressed concurrently at 10 h of development. However, enzyme activity did not appear until 18 h, coincident with a decrease in the level of the 113-kDa peptide and a corresponding increase in the amount of a 106-kDa GP2 peptide. Addition of cAMP to aggregation-competent cells in liquid culture resulted in the induction of GP2 mRNA, GP2 protein, and GP2 enzyme activity.
- Yamada, Y., Selmin, O. I., Ruggiero, F., R, D., Pfaffle, M., Martin, G., Mark, K. V., M, B., K, V. D., Garrone, R., G, M., Fernandez, M. P., Deutzmann, R., & Borchert, M. (1990). Anchorin CII, a collagen-binding chondrocyte surface protein of the calpactin family.. Progress in clinical and biological research, 349, 147-57.More infoIn an attempt to identify collagen-binding proteins on the chondrocyte surface, a protein of Mr 34KD, called Anchorin CII was isolated from chondrocyte membranes by affinity chromatography on type II collagen sepharose (Mollenhauer & von der Mark, 1983). The protein was localized on the chondrocyte surface by immunofluorescence labeling using a specific rabbit antibody (Mollenhauer et al., 1984), by immunogold labeling and by cell surface iodination (Pfäffle et al., 1988). Fab'fragments of anti anchorin CII reduced the binding of chondrocytes to type II collagen substrates (Mollenhauer et al., 1984). Analysis of the complete primary structure of anchorin CII revealed 4 repetitive domains of each 70-80 amino acid residues, and the absence of hydrophobic transmembrane sequences or signal peptides (Fernández et al., 1988). Thus, anchorin CII is another member of the calpactin/lipocortin/annexin family, although most other members of this family are located strictly intracellularly. Similar to lipocortin I, however, anchorin CII can be identified extracellularly, e.g. in the culture medium of chondrocytes and fibroblasts (Pfäffle et al., 1988). Here we report on further studies on sequence homologies to other annexins, and on the Ca(++)- and phospholipide binding of this protein.
- Sucic, J. F., Selmin, O. I., Rutherford, C. L., Rogers, P. V., Naranan, V., & Brickey, D. A. (1988). Glycogen phosphorylase in Dictyostelium discoideum: demonstration of two developmentally regulated forms, purification to homogeneity, immunochemical analysis, cAMP induction, in vitro translation, and molecular cloning.. Developmental genetics, 9(4-5), 469-81. doi:10.1002/dvg.1020090424More infoA key step in the cellular differentiation of Dictyostelium is the degradation of glycogen to provide the precursors for synthesis of the structural end products of development. We have found that the enzyme that initiates this degradative pathway, glycogen phosphorylase (1,4-alpha-D-glucan:orthophosphate alpha-glucosyltransferase; EC 2.4.1.1), is developmentally regulated and exists as two forms. During the time course of development, a previously undescribed activity, the "b" form, decreases, while that of the "a" form increases. The "b" form is inactive unless 5'AMP is included in the reaction mixture. The two forms differ in their elution from DE52 cellulose, affinity constants, thermal stability, affinity for 5'AMP Sepharose, subunit molecular weight, and peptide maps. In crude extracts, anti-a antiserum stains a 104-kD protein that is associated with phosphorylase "a" activity and appears late in development, while anti-b antiserum stains a 92-kD protein that is associated with phosphorylase "b" activity and is present throughout development. We have also demonstrated in vitro phosphorylation of the "b" form by an endogenous protein kinase and a corresponding loss of 5'AMP dependence. If intact cells were exposed to exogenous cAMP, "b" activity decreased and was replaced by "a" activity, as well as the 104-kD protein band on SDS-PAGE. In order to determine if the two forms of the enzyme are different gene products, we screened lambda gt11 expression libraries with antibodies against the purified "a" and "b" forms. Three clones were found to be overlapping by Southern analysis. A yeast glycogen phosphorylase cDNA clone (gpy) and a human muscle glycogen phosphorylase clone (HM-11) cross-hybridized with the Dictyostelium inserts, and gpy shared a few common restriction fragments with the Dictyostelium clones on genomic blots. Northern analysis of Dictyostelium total RNA showed that the Dictyostelium inserts and gpy recognize an mRNA of 3.2 kb, while on poly A-enriched RNA, the yeast clone detects preferentially a 3.6-kb message.
- Yamada, Y., Selmin, O. I., Pfaffle, M., Mollenhauer, J., Martin, G. R., Mark, K. V., Fernandez, M. P., & Deutzmann, R. (1988). The structure of anchorin CII, a collagen binding protein isolated from chondrocyte membrane.. Journal of Biological Chemistry, 263(12), 5921-5925. doi:10.1016/s0021-9258(18)60653-2More infoAbstract cDNA clones for anchorin CII (Mr = 34,000), a collagen-binding protein, were isolated from a lambda gt 11 cDNA library prepared from chick cartilage mRNA. Several overlapping clones were characterized which gave rise to an open reading frame coding for 329 residues and a 3'-untranslated segment of 500 base pairs. The clones were identified as coding for anchorin by hybrid select translation analysis and by comparing the deduced amino acid sequence with the sequence of 10 tryptic peptides of the protein. A hydrophobic domain of 25 residues interrupted with 3 polar residues was identified with the carboxyl-terminal portion. There was no evidence for an aminoterminal signal peptide. Northern analysis revealed that the 5' probe hybridizes to a single 1.7-kilobases (kb) mRNA species, whereas the 3' probe hybridizes to two mRNA species of 1.7 kb and 5 kb, which are present in many cells including chondrocytes, crop cells, and fibroblasts. The level of anchorin mRNA in chick embryo fibroblasts was increased by infection with Rous sarcoma virus.
- Yamada, Y., Selmin, O. I., Ruggiero, F., Pfaffle, M., Mark, K. V., Hofmann, H., Garrone, R., & Fernandez, M. P. (1988). Biosynthesis, secretion and extracellular localization of anchorin CII, a collagen-binding protein of the calpactin family.. The EMBO Journal, 7(8), 2335-2342. doi:10.1002/j.1460-2075.1988.tb03077.xMore infoThe amino acid sequence of anchorin CII, a collagen-binding protein isolated originally from chondrocyte membranes, was previously determined by sequencing of cDNA and proteolytic fragments of the protein. Computer analysis of the protein sequence revealed four internal repeats of approximately 70-80 residues, each containing a highly conserved consensus sequence of 17 residues. These repeats show considerable homology with sequences in human and bovine calpactin, lipocortin, endonexin and protein II, which are members of a family of Ca2+- and phospholipid-binding proteins, as well as major substrates of tyrosine kinases. While these proteins have been located at the inner side of the plasma membrane of fibroblasts and epithelial cells, here we present experimental evidence that anchorin CII is at least partially released from cells and binds to the outer cell surface. Biosynthesis studies in cell-free systems and in cell culture indicate that anchorin CII is not processed, which is consistent with the absence of signal sequences from the protein. Yet, pulse-chase experiments show that anchorin is released into the culture medium of fibroblasts after 30 min, and in chondrocyte cultures after 20 h. Anchorin CII was located to the outer cell surface of chondrocytes by lactoperoxidase-catalyzed cell surface iodination as well as by antibody labeling both at light- and electron-microscopical level. The pericellular localization of anchorin CII is consistent with the notion that this protein is involved in the interaction of chondrocytes and fibroblasts with extracellular collagen.
Proceedings Publications
- Donovan, M. G., Selmin, O. I., Romagnolo, D. F., Donovan, M. G., & Doetschman, T. C. (2019). Abstract 1604: Modulating effects of genistein in a mouse model of conditionalBRCA1deletion and triple negative breast cancer cells. In Prevention, Early Detection, and Interception.
- Donovan, M. G., Selmin, O. I., Romagnolo, D. F., & Donovan, M. G. (2018). Abstract 1385: Galangin is an epigenetic modulator or BRCA1 and induces estrogen receptor alpha in triple negative breast cancer cells. In Molecular and Cellular Biology / Genetics.
Poster Presentations
- Selmin, O. (2018, April). Galangin is an epigenetic modulator of BRCA1 and induces estrogen receptor alpha in TNBC cells. AACR Conference Abstract #7597.
- Selmin, O. (2018, March). Flavones counteract epigenetic silencing of BRCA1 in breast cancer cells with activated AhR. CALS Poster Forum.
- Selmin, O. (2018, October). Arsenic-induced BRCA1CpG promoter methylation associates with downregulation of ERalpha and resistance to tamoxifen. 3rd annual University of Arizona Cancer Center Scientific Symposium and Retreat.