Elsa M Reyes Reyes

Interests

Teaching

Teaching Interests:1) Educate the next generation of scientists that requires providing students with knowledge, insights and enthusiasm required for successful careers in science.2) Show interest in the students by stimulating their interest, encouraging discussion, explaining topics clearly and showing enthusiasm.3) Active learning which aims at students becoming active participants in the learning process.4) Understand and apply the scientific method experiencing the joy of discovery, develop critical-thinking skills, and learn to work together as part of a problem-solving team.

Research

My primary research interest is to elucidate gene-environment interactions leading to cancer. I am particularly interested is determine how nucleolin participate in the development and progression of prostate cancer. Nucleolin is a multifunctional protein, expressed in the nucleus of most cell types, but selectively over expressed in the cytoplasm and on the surface of cancer cells. Non-nuclear forms of nucleolin have been involved in the regulation of several oncogenic pathways, suggesting that non-nuclear forms of nucleolin is target for therapeutic application.

Courses

Scholarly Contributions

Books

• Ramos, K. S., Reyes Reyes, E. M., & Nanez, A. (2015). Overview of Receptor Systems. Reference Module in Biomedical Sciences: Elsevier Inc.. doi:10.1016/B978-0-12-801238-3.01906-1
• Ramos, K. S., Reyes Reyes, E. M., & Weber, T. J. (2015). Overview of Alterations in Cell Signaling. Reference Module in Biomedical Sciences: Elsevier Inc.. doi:http://dx.doi.org/10.1016/B978-0-12-801238-3.01924-3

Journals/Publications

• Reyes-Reyes, E. M., & Bates, P. J. (2019). Characterizing Oligonucleotide Uptake in Cultured Cells: A Case Study Using AS1411 Aptamer. Methods in molecular biology (Clifton, N.J.), 2036, 173-186.
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  Oligonucleotides can be designed or evolved to bind to specific DNA, RNA, protein, or small molecule targets and thereby alter the biological function of the target. The therapeutic potential of oligonucleotides targeted to intracellular molecules will depend largely on their ability to be taken up by the cells of interest, as well as their subsequent subcellular distribution. Here we describe methods to characterize the extent and mechanism of cellular uptake of AS1411, an aptamer oligonucleotide that has progressed to human clinical trials and which is also widely used by researchers as a cancer-targeting ligand.
• Garza-Lombó, C., Schroder, A., Reyes-Reyes, E. M., & Franco, R. (2018). mTOR/AMPK signaling in the brain: Cell metabolism, proteostasis and survival. Current opinion in toxicology, 8, 102-110.
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  The mechanistic (or mammalian) target of rapamycin (mTOR) and the adenosine monophosphate-activated protein kinase (AMPK) regulate cell survival and metabolism in response to diverse stimuli such as variations in amino acid content, changes in cellular bioenergetics, oxygen levels, neurotrophic factors and xenobiotics. This Opinion paper aims to discuss the current state of knowledge regarding how mTOR and AMPK regulate the metabolism and survival of brain cells and the close interrelationship between both signaling cascades. It is now clear that both mTOR and AMPK pathways regulate cellular homeostasis at multiple levels. Studies so far demonstrate that dysregulation in these two pathways is associated with neuronal injury, degeneration and neurotoxicity, but the mechanisms involved remain unclear. Most of the work so far has been focused on their antagonistic regulation of autophagy, but recent findings highlight that changes in protein synthesis, metabolism and mitochondrial function are likely to play a role in the regulatory effects of both mTOR and AMPK on neuronal health. Understanding the role and relationship between these two master regulators of cell metabolism is crucial for future therapeutic approaches to counteract alterations in cell metabolism and survival in brain injury and disease.
• Khalid, M., Bojang, P., Hassanin, A. A., Reyes-Reyes, E. M., Bowers, E. C., Ramos, I. N., & Ramos, K. S. (2018). Line-1: Implications in the etiology of cancer, clinical applications, and pharmacologic targets. Mutation research, 778, 51-60.
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  Long interspersed nuclear elements-1 (Line-1 or L1) accounts for approximately 17% of the human genome. The majority of L1s are inactive, but ∼100 remain retrotransposon competent (RC-L1) and able to retrotranspose through RNA intermediates to different locations of the genome. L1 is involved in both disease initiation and progression via retrotransposition dependent and independent mechanisms. Retrotransposed L1 sequences disrupt genetic loci at sites of insertion, while the activities of L1 si/piRNAs, mRNAs, and ORF1 and ORF2 proteins, and have been implicated in the etiology and progression of several human diseases. Despite these relationships, little is known about the clinical utility of L1 as a biomarker of disease initiation and progression, or the utility of small molecules to inhibit and reverse the harmful effects of L1. In this review, we discuss the life cycle of L1, somatic and germline inhibitions, the mechanisms of L1 retrotransposition dependent and independent disease initiation and progression, clinical utilities, and potential of L1s as pharmacologic targets for the treatment of cancer.
• Stivers, N. S., Islam, A., Reyes-Reyes, E. M., Casson, L. K., Aponte, J. C., Vaisberg, A. J., Hammond, G. B., & Bates, P. J. (2018). Plagiochiline A Inhibits Cytokinetic Abscission and Induces Cell Death. Molecules (Basel, Switzerland), 23(6).
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  We previously reported on the isolation and biological activities of plagiochiline A (), a 2,3-secoaromadendrane-type sesquiterpenoid from the Peruvian medicinal plant, . This compound was found to have antiproliferative effects on a variety of solid tumor cell lines, as well as several leukemia cell lines. Other researchers have also noted the cytotoxicity of plagiochiline A (isolated from different plant species), but there are no prior reports regarding the mechanism for this bioactivity. Here, we have evaluated the effects of plagiochiline A on cell cycle progression in DU145 prostate cancer cells. A cell cycle analysis indicated that plagiochiline A caused a significant increase in the percentage of cells in the G₂/M phase when compared with control cells. When cells were stained and observed by fluorescence microscopy to examine progress through the mitotic phase, we found a significant increase in the proportion of cells with features of late cytokinesis (cells connected by intercellular bridges) in the plagiochiline A-treated samples. These results suggest that plagiochiline A inhibits cell division by preventing completion of cytokinesis, particularly at the final abscission stage. We also determined that plagiochiline A reduces DU145 cell survival in clonogenic assays and that it induces substantial cell death in these cells.
• Bates, P. J., Reyes-Reyes, E. M., Malik, M. T., Murphy, E. M., O'Toole, M. G., & Trent, J. O. (2017). G-quadruplex oligonucleotide AS1411 as a cancer-targeting agent: Uses and mechanisms. Biochimica et biophysica acta. General subjects, 1861(5 Pt B), 1414-1428.
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  AS1411 is a 26-mer G-rich DNA oligonucleotide that forms a variety of G-quadruplex structures. It was identified based on its cancer-selective antiproliferative activity and subsequently determined to be an aptamer to nucleolin, a multifunctional protein that preferentially binds quadruplex nucleic acids and which is present at high levels on the surface of cancer cells. AS1411 has exceptionally efficient cellular internalization compared to non-quadruplex DNA sequences.
• Reyes-Reyes, E. M., Aispuro, I., Tavera-Garcia, M. A., Field, M., Moore, S., Ramos, I., & Ramos, K. S. (2017). LINE-1 couples EMT programming with acquisition of oncogenic phenotypes in human bronchial epithelial cells. Oncotarget, 8(61), 103828-103842.
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  Although several lines of evidence have established the central role of epithelial-to-mesenchymal-transition (EMT) in malignant progression of non-small cell lung cancers (NSCLCs), the molecular events connecting EMT to malignancy remain poorly understood. This study presents evidence that Long Interspersed Nuclear Element-1 (LINE-1) retrotransposon couples EMT programming with malignancy in human bronchial epithelial cells (BEAS-2B). This conclusion is supported by studies showing that: 1) activation of EMT programming by TGF-β1 increases LINE-1 mRNAs and protein; 2) the lung carcinogen benzo(a)pyrene coregulates TGF-β1 and LINE-1 mRNAs, with LINE-1 positioned downstream of TGF-β1 signaling; and, 3) forced expression of LINE-1 in BEAS-2B cells recapitulates EMT programming and induces malignant phenotypes and tumorigenesis . These findings identify a TGFβ1-LINE-1 axis as a critical effector pathway that can be targeted for the development of precision therapies during malignant progression of intractable NSCLCs.
• Reyes Reyes, E. M., Ramos, I., Tavera-Garcia, M. A., & Ramos, K. S. (2016). The Aryl Hydrocarbon Receptor Agonist Benzo(a)pyrene Reactivates LINE-1 in HepG2 Cells Through Canonical TGF-b1 Signaling: Implications in Hepatocellular Carcinogenesis.. Am J Cancer Res.
• Reyes-Reyes, E. M., Ramos, I. N., Tavera-Garcia, M. A., & Ramos, K. S. (2016). The aryl hydrocarbon receptor agonist benzo(a)pyrene reactivates LINE-1 in HepG2 cells through canonical TGF-β1 signaling: implications in hepatocellular carcinogenesis. American journal of cancer research, 6(5), 1066-77.
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  Long interspersed nuclear element-1 (L1) is a genetic element that mobilizes throughout the mammalian genome via retrotransposition and damages host DNA via mutational insertions, chromosomal rearrangements, and reprogramming of gene expression. The cellular mechanisms responsible for aberrant L1 expression during cancer pathogenesis are unclear. Previously, we have shown that L1 reactivation in several human cell lines is dependent upon the activation of aryl hydrocarbon receptor (AhR), a ligand-activated transcription factor member of the PAS superfamily of proteins. We also showed that ectopic expression of L1 reprograms the HepG2 genome leading to epithelial-to-mesenchymal transition (EMT). Here we present evidence that reactivation of L1 and modulation of EMT in HepG2 cells by the AhR ligand benzo(a)pyrene (BaP) is effected through the canonical TGF-β1 signaling pathway. BaP increased TGF-β1 mRNA, SMAD2 phosphorylation and decreased expression of E-Cadherin. The functional relevance of these interactions and the involvement of TGFBR1/ALK5 and SMAD2/3 were confirmed by siRNA interference. Furthermore, expression of L1-encoded ORF1p was positively correlated with the activation of TGF-β1 signaling in human hepatocarcinoma samples at various stages of malignant progression. These results indicate that ligand-mediated AhR activation regulates L1 via canonical TGF-β1 signaling and raise important questions about the molecular etiology of human hepatocarcinomas.
• Anandhan, A., Rodriguez-Rocha, H., Bohovych, I., Griggs, A. M., Zavala-Flores, L., Reyes-Reyes, E. M., Seravalli, J., Stanciu, L. A., Lee, J., Rochet, J. C., Khalimonchuk, O., & Franco, R. (2015). Overexpression of alpha-synuclein at non-toxic levels increases dopaminergic cell death induced by copper exposure via modulation of protein degradation pathways. Neurobiology of disease, 81, 76-92.
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  Gene multiplications or point mutations in alpha (α)-synuclein are associated with familial and sporadic Parkinson's disease (PD). An increase in copper (Cu) levels has been reported in the cerebrospinal fluid and blood of PD patients, while occupational exposure to Cu has been suggested to augment the risk to develop PD. We aimed to elucidate the mechanisms by which α-synuclein and Cu regulate dopaminergic cell death. Short-term overexpression of wild type (WT) or mutant A53T α-synuclein had no toxic effect in human dopaminergic cells and primary midbrain cultures, but it exerted a synergistic effect on Cu-induced cell death. Cell death induced by Cu was potentiated by overexpression of the Cu transporter protein 1 (Ctr1) and depletion of intracellular glutathione (GSH) indicating that the toxic effects of Cu are linked to alterations in its intracellular homeostasis. Using the redox sensor roGFP, we demonstrated that Cu-induced oxidative stress was primarily localized in the cytosol and not in the mitochondria. However, α-synuclein overexpression had no effect on Cu-induced oxidative stress. WT or A53T α-synuclein overexpression exacerbated Cu toxicity in dopaminergic and yeast cells in the absence of α-synuclein aggregation. Cu increased autophagic flux and protein ubiquitination. Impairment of autophagy by overexpression of a dominant negative Atg5 form or inhibition of the ubiquitin/proteasome system (UPS) with MG132 enhanced Cu-induced cell death. However, only inhibition of the UPS stimulated the synergistic toxic effects of Cu and α-synuclein overexpression. Our results demonstrate that α-synuclein stimulates Cu toxicity in dopaminergic cells independent from its aggregation via modulation of protein degradation pathways.
• Malik, M. T., O'Toole, M. G., Casson, L. K., Thomas, S. D., Bardi, G. T., Reyes-Reyes, E. M., Ng, C. K., Kang, K. A., & Bates, P. J. (2015). AS1411-conjugated gold nanospheres and their potential for breast cancer therapy. Oncotarget, 6(26), 22270-81.
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  AS1411 is a quadruplex-forming DNA oligonucleotide that functions as an aptamer to target nucleolin, a protein present on the surface of cancer cells. Clinical trials of AS1411 have indicated it is well tolerated with evidence of therapeutic activity, but improved pharmacology and potency may be required for optimal efficacy. In this report, we describe how conjugating AS1411 to 5 nm gold nanospheres influences its activities in vitro and in vivo. We find that the AS1411-linked gold nanospheres (AS1411-GNS) are stable in aqueous and serum-containing solutions. Compared to unconjugated AS1411 or GNS linked to control oligonucleotides, AS1411-GNS have superior cellular uptake and markedly increased antiproliferative/cytotoxic effects. Similar to AS1411, AS1411-GNS show selectivity for cancer cells compared to non-malignant cells. In a mouse model of breast cancer, systemic administration of AS1411-GNS could completely inhibit tumor growth with no signs of toxicity. These results suggest AS1411-GNS are promising candidates for clinical translation.
• Reyes-Reyes, E. M., Šalipur, F. R., Shams, M., Forsthoefel, M. K., & Bates, P. J. (2015). Mechanistic studies of anticancer aptamer AS1411 reveal a novel role for nucleolin in regulating Rac1 activation. Molecular oncology, 9(7), 1392-405.
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  AS1411 is a G-rich quadruplex-forming oligodeoxynucleotide that binds specifically to nucleolin, a protein found on the surface and in the cytoplasm of most malignant cells but absent from the surface/cytoplasm of most normal cells. AS1411 has shown promising clinical activity and is being widely used as a tumor-targeting agent, but its mechanism of action is not fully understood. Previously, we showed that AS1411 is taken up in cancer cells by macropinocytosis (fluid phase endocytosis) and subsequently stimulates further macropinocytosis by a nucleolin-dependent mechanism. In the current study, we have investigated the significance and molecular mechanisms of AS1411-induced macropinocytosis. Our results indicate that the antiproliferative activity of AS1411 in various cell lines correlated with its capacity to stimulate macropinocytosis. In DU145 prostate cancer cells, AS1411 induced activation of EGFR, Akt, p38, and Rac1. Activation of Akt and p38 were not critical for AS1411 activity because Akt activation was not observed in all AS1411-responsive cell lines and knockdown of p38 had no effect on AS1411's ability to inhibit proliferation. On the other hand, activation of EGFR and Rac1 appeared to play a role in AS1411 activity in all cancer cell lines examined (DU145, MDA-MB-468, A549, LNCaP) and their inhibition significantly reduced AS1411-mediated macropinocytosis and AS1411 antiproliferative activity. Interestingly, downregulation of nucleolin expression by siRNA also produced a substantial increase in activated Rac1, revealing a previously unknown role for nucleolin as a negative regulator of Rac1 activation. Our results are consistent with a model whereby AS1411 binding to nucleolin leads to sustained activation of Rac1 and causes methuosis, a novel type of nonapoptotic cell death characterized by hyperstimulation of macropinocytosis. We speculate that methuosis is a tumor/metastasis suppressor mechanism that opposes the malignant functions of Rac1 and that cancer cells may overexpress nucleolin to surmount this barrier.