Sally E Dickinson
- Assistant Research Scientist, Cancer Center Division
- Research Associate Professor, Pharmacology
I am a Research Assistant Professor in Pharmacology working at the University of Arizona Cancer Center. My scientific training and current research are in the area of UV-induced skin carcinogenesis with a focus on molecular signaling pathways as targets for chemoprevention. Through this training, I have gained extensive experience with mouse models of non-melanoma skin cancer (NMSC), cell/molecular biology techniques and translational studies. As a faculty member of the University of Arizona Cancer Center, I am currently the Co-PI of Project 1 of the Chemoprevention of Skin Cancer Program Project Grant (PPG). Through this grant we are investigating the roles of MAP Kinases, PI3-Kinase, and mTOR/Akt signaling in the development of UV-induced NMSC. We are focused on exploring the use of specific inhibitors of these pathways as chemopreventive agents. We are currently investigating the activities of Rapamycin (an mTOR inhibitor), PHT-427 (a PDK1/Akt inhibitor) and the natural product sulforaphane (SFN, a Nrf2 inducer) in skin cancer prevention, the latter as an extension of my K07 Career Development award. In fact, the PPG recently conducted a pilot clinical trial using topical SFN to examine its effects on epidermal signaling in the context of solar-simulated light. In addition, we are interested in examining the use of other natural products alone or in combination to boost our efficiency at topically preventing NMSC in the general population and in high-risk patients such as those subject to immunosuppression. We are also expanding our reserach into the role of inflammatory signaling in skin cancer development by exploring the role of Toll-like receptor 4 (TLR4) in UV-induced cell signaling in keratinocytes.
- Ph.D. Genetics
- University of Arizona, Tucson, Arizona, United States
- Early responses to oxidative stress in heart cells: signals from the cell membrane to the nucleus and beyond
- B.S. Biology
- University of Puget Sound, Tacoma, Washington, United States
- University of Arizona, Tucson, Arizona (2009 - Ongoing)
- University of Arizona Cancer Center (2008 - 2013)
- University of Arizona Cancer Center (2005 - 2009)
Skin cancer, ultraviolet light, signal transduction, stress responses, oxidative stress, Nrf2, MAPKinases, mTOR/AKT signaling, transgenic mice, natural products, sulforaphane, TLR4, AP-1, NF-kB, inflammation
Intro to PharmacologyPHCL 412 (Fall 2022)
Intro to PharmacologyPHCL 512 (Fall 2022)
Honors ThesisBIOC 498H (Spring 2022)
Independent StudyMCB 399 (Spring 2022)
Honors ThesisBIOC 498H (Fall 2021)
Intro to PharmacologyPHCL 412 (Fall 2021)
Intro to PharmacologyPHCL 512 (Fall 2021)
Directed ResearchMCB 792 (Fall 2020)
Intro to PharmacologyPHCL 412 (Fall 2020)
Intro to PharmacologyPHCL 512 (Fall 2020)
Intro to PharmacologyPHCL 412 (Fall 2019)
Intro to PharmacologyPHCL 512 (Fall 2019)
Honors Independent StudyMCB 399H (Spring 2019)
Honors ThesisECOL 498H (Spring 2017)
Honors ThesisECOL 498H (Fall 2016)
ThesisPHCL 910 (Fall 2016)
ThesisPHCL 910 (Summer I 2016)
ThesisPHCL 910 (Spring 2016)
- Adams, A. C., Macy, A. M., Saboda, K., Dickinson, S. E., Glembocki, D. J., Roe, D. J., & Hastings, K. T. (2021). Solar Simulated Light Induces Cutaneous Squamous Cell Carcinoma in Inbred Mice: A Clinically Relevant Model to Investigate T-Cell Responses. The Journal of investigative dermatology, 141(12), 2990-2993.e6.
- Dickinson, S. E., Khawam, M., Kirschnerova, V., Vaishampayan, P., Centuori, S. M., Saboda, K., Calvert, V. S., Petricoin, E. F., & Curiel-Lewandrowski, C. (2021). Increased PD-L1 Expression in Human Skin Acutely and Chronically Exposed to UV Irradiation. Photochemistry and photobiology, 97(4), 778-784.More infoOverexpression of PD-L1 (CD274) on tumor cells may represent a hallmark of immune evasion, and overexpression has been documented in several tumors including cutaneous squamous cell carcinoma (cSCC). While PD-L1/PD-1 activity in the skin has been primarily described in inflammatory models, our goal was to examine PD-L1 expression in human keratinocytes exposed to UV irradiation. We assessed PD-L1 expression in human sun-protected (SP) and sun-damaged (SD) skin, actinic keratosis (AK), and cSCC using IHC and protein microarray. Both methods found low baseline levels of PD-L1 in SP and SD skin and significantly increased expression in cSCC. Next, we examined PD-L1 expression in acute models of UV exposure. In human SP skin exposed to 2-3 MED of UV (n = 20), epidermal PD-L1 was induced in 70% of subjects after 24 h (P = 0.0001). SKH-1 mice exposed to acute UV also showed significant epidermal PD-L1 induction at 16, 24 and 48 h. A time- and dose-dependent induction of PD-L1 was confirmed in cultured human keratinocytes after UV, which was markedly reduced in the presence of MEK/ERK, JNK or STAT3 inhibitors. These findings suggest that UV induces upregulation of PD-L1 through established, pharmacologically targetable stress-signaling pathways in keratinocytes.
- Jandova, J., Snell, J., Hua, A., Dickinson, S., Fimbres, J., & Wondrak, G. T. (2021). Topical hypochlorous acid (HOCl) blocks inflammatory gene expression and tumorigenic progression in UV-exposed SKH-1 high risk mouse skin. Redox biology, 45, 102042.More infoHypochlorous acid (HOCl) is the active oxidizing principle underlying drinking water disinfection, also delivered by numerous skin disinfectants and released by standard swimming pool chemicals used on a global scale, a topic of particular relevance in the context of the ongoing COVID-19 pandemic. However, the cutaneous consequences of human exposure to HOCl remain largely unknown, posing a major public health concern. Here, for the first time, we have profiled the HOCl-induced stress response in reconstructed human epidermis and SKH-1 hairless mouse skin. In addition, we have investigated the molecular consequences of solar simulated ultraviolet (UV) radiation and HOCl combinations, a procedure mimicking co-exposure experienced for example by recreational swimmers exposed to both HOCl (pool disinfectant) and UV (solar radiation). First, gene expression elicited by acute topical HOCl exposure was profiled in organotypic human reconstructed epidermis. Next, co-exposure studies (combining topical HOCl and UV) performed in SKH-1 hairless mouse skin revealed that the HOCl-induced cutaneous stress response blocks redox and inflammatory gene expression elicited by subsequent acute UV exposure (Nos2, Ptgs2, Hmox1, Srxn1), a finding consistent with emerging clinical evidence in support of a therapeutic role of topical HOCl formulations for the suppression of inflammatory skin conditions (e.g. atopic dermatitis, psoriasis). Likewise, in AP-1 transgenic SKH-1 luciferase-reporter mice, topical HOCl suppressed UV-induced inflammatory signaling assessed by bioluminescent imaging and gene expression analysis. In the SKH-1 high-risk mouse model of UV-induced human keratinocytic skin cancer, topical HOCl blocked tumorigenic progression and inflammatory gene expression (Ptgs2, Il19, Tlr4), confirmed by immunohistochemical analysis including 3-chloro-tyrosine-epitopes. These data illuminate the molecular consequences of HOCl-exposure in cutaneous organotypic and murine models assessing inflammatory gene expression and modulation of UV-induced carcinogenesis. If translatable to human skin these observations provide novel insights on molecular consequences of chlorination stress relevant to environmental exposure and therapeutic intervention.
- Nguyen, T. N., Rajapakshe, K., Nicholas, C., Tordesillas, L., Ehli, E. A., Davis, C. M., Coarfa, C., Flores, E. R., Dickinson, S. E., Curiel-Lewandrowski, C., & Tsai, K. Y. (2020). Integrative transcriptomic analysis for linking acute stress responses to squamous cell carcinoma development. Scientific reports, 10(1), 17209.More infoCutaneous squamous cell carcinoma (cuSCC) is the second most common skin cancer and commonly arises in chronically UV-exposed skin or chronic wounds. Since UV exposure and chronic wounds are the two most prominent environmental factors that lead to cuSCC initiation, we undertook this study to test whether more acute molecular responses to UV and wounding overlapped with molecular signatures of cuSCC. We reasoned that transcriptional signatures in common between acutely UV-exposed skin, wounded skin, and cuSCC tumors, might enable us to identify important pathways contributing to cuSCC. We performed transcriptomic analysis on acutely UV-exposed human skin and integrated those findings with datasets from wounded skin and our transcriptomic data on cuSCC using functional pair analysis, GSEA, and pathway analysis. Integrated analyses revealed significant overlap between these three datasets, thus highlighting deep molecular similarities these biological processes, and we identified Oncostatin M (OSM) as a potential common upstream driver. Expression of OSM and its downstream targets correlated with poorer overall survival in head and neck SCC patients. In vitro, OSM promoted invasiveness of keratinocytes and cuSCC cells and suppressed apoptosis of irradiated keratinocytes. Together, these results support the concept of using an integrated, biologically-informed approach to identify potential promoters of tumorigenesis.
- Dickinson, S. E., & Wondrak, G. T. (2019). TLR4 in skin cancer: From molecular mechanisms to clinical interventions. MOLECULAR CARCINOGENESIS, 58(7), 1086-1093.
- Blohm-Mangone, K., Burkett, N. B., Tahsin, S., Myrdal, P. B., Aodah, A., Ho, B., Janda, J., McComas, M., Saboda, K., Roe, D. J., Dong, Z., Bode, A. M., Petricoin, E. F., Calvert, V. S., Curiel-Lewandrowski, C., Alberts, D. S., Wondrak, G. T., & Dickinson, S. E. (2018). Pharmacological TLR4 Antagonism Using Topical Resatorvid Blocks Solar UV-Induced Skin Tumorigenesis in SKH-1 Mice. Cancer prevention research (Philadelphia, Pa.), 11(5), 265-278.More infoAn urgent need exists for the development of more efficacious molecular strategies targeting nonmelanoma skin cancer (NMSC), the most common malignancy worldwide. Inflammatory signaling downstream of Toll-like receptor 4 (TLR4) has been implicated in several forms of tumorigenesis, yet its role in solar UV-induced skin carcinogenesis remains undefined. We have previously shown in keratinocyte cell culture and SKH-1 mouse epidermis that topical application of the specific TLR4 antagonist resatorvid (TAK-242) blocks acute UV-induced AP-1 and NF-κB signaling, associated with downregulation of inflammatory mediators and MAP kinase phosphorylation. We therefore explored TLR4 as a novel target for chemoprevention of UV-induced NMSC. We selected the clinical TLR4 antagonist resatorvid based upon target specificity, potency, and physicochemical properties. Here, we confirm using permeability assays that topical resatorvid can be effectively delivered to skin, and using studies that topical resatorvid can block UV-induced AP-1 activation in mouse epidermis. We also report that in a UV-induced skin tumorigenesis model, topical resatorvid displays potent photochemopreventive activity, significantly suppressing tumor area and multiplicity. Tumors harvested from resatorvid-treated mice display reduced activity of UV-associated signaling pathways and a corresponding increase in apoptosis compared with tumors from control animals. Further mechanistic insight on resatorvid-based photochemoprevention was obtained from unsupervised hierarchical clustering analysis of protein readouts via reverse-phase protein microarray revealing a significant attenuation of key UV-induced proteomic changes by resatorvid in chronically treated high-risk SKH-1 skin prior to tumorigenesis. Taken together, our data identify TLR4 as a novel molecular target for topical photochemoprevention of NMSC. .
- Dickinson, S. E., & Wondrak, G. T. (2018). TLR4-directed Molecular Strategies Targeting Skin Phoodaage and Carcinogenesis. CURRENT MEDICINAL CHEMISTRY, 25(40), 5487-5502.
- Roh, E., Lee, M. H., Zykova, T. A., Zhu, F., Nadas, J., Kim, H. G., Bae, K. B., Li, Y., Cho, Y. Y., Curiel-Lewandrowski, C., Einspahr, J., Dickinson, S. E., Bode, A. M., & Dong, Z. (2018). Targeting PRPK and TOPK for skin cancer prevention and therapy. Oncogene, 37(42), 5633-5647.More infoSolar ultraviolet (sUV) irradiation is a major environmental carcinogen that can cause inflammation and skin cancer. The costs and morbidity associated with skin cancer are increasing, and therefore identifying molecules that can help prevent skin carcinogenesis is important. In this study, we identified the p53-related protein kinase (PRPK) as a novel oncogenic protein that is phosphorylated by the T-LAK cell-originated protein kinase (TOPK). Knockdown of TOPK inhibited PRPK phosphorylation and conferred resistance to solar-simulated light (SSL)-induced skin carcinogenesis in mouse models. In the clinic, acute SSL irradiation significantly increased epidermal thickness as well as total protein and phosphorylation levels of TOPK and PRPK in human skin tissues. We identified two PRPK inhibitors, FDA-approved rocuronium bromide (Zemuron) or betamethasone 17-valerate (Betaderm) that could attenuate TOPK-dependent PRPK signaling. Importantly, topical application of either rocuronium bromide or betamethasone decreased SSL-induced epidermal hyperplasia, neovascularization, and cutaneous squamous cell carcinoma (cSCC) development in SKH1 (Crl: SKH1-Hr) hairless mice by inhibiting PRPK activation, and also reduced expression of the proliferation and oncogenesis markers, COX-2, cyclin D1, and MMP-9. This study is the first to demonstrate that targeting PRPK could be useful against sUV-induced cSCC development.
- Dickinson, S. E., & Wondrak, G. T. (2017). TLR4-directed Molecular Strategies Targeting Skin Photodamage and Carcinogenesis. Current medicinal chemistry.More infoExposure to solar ultraviolet (UV) radiation is a causative factor in skin photodamage and carcinogenesis, and inflammatory dysregulation is a key mechanism underlying detrimental effects of acute and chronic UV exposure. The health and economic burden of skin cancer treatment is substantial, creating an increasingly urgent need for the development of improved molecular strategies for photoprotection and photochemoprevention. The role of Toll-like receptor 4 (TLR4) as a key regulator of skin anti-microbial defense, wound healing, and cutaneous tumorigenic inflammation has now been recognized, and recently published evidence suggests that TLR4 represents a novel molecular target for skin photoprotection and cancer photochemoprevention. Specifically, it has been shown that pharmacological and genetic antagonism of TLR4 suppresses UV-induced inflammatory signaling involving the attenuation of cutaneous NF-κB and AP-1 stress signaling observable in vitro and in vivo. A number of TLR4-directed small molecule pharmacological antagonists [including eritoran, (+)-naloxone, ST2825, and resatorvid] have now been identified and are at various stages of preclinical and clinical development for the modulation of dysregulated TLR4-dependent inflammatory signaling.
- Einspahr, J. G., Curiel-Lewandrowski, C., Calvert, V. S., Stratton, S. P., Alberts, D. S., Warneke, J., Hu, C., Saboda, K., Wagener, E. L., Dickinson, S., Dong, Z., Bode, A. M., & PetricoinIII, E. F. (2017). Protein activation mapping of human sun-protected epidermis after an acute dose of erythemic solar simulated light. NPJ precision oncology, 1.More infoUltraviolet radiation is an important etiologic factor in skin cancer and a better understanding of how solar stimulated light (SSL) affects signal transduction pathways in human skin which is needed in further understanding activated networks that could be targeted for skin cancer prevention. We utilized Reverse Phase Protein Microarray Analysis (RPPA), a powerful technology that allows for broad-scale and quantitative measurement of the activation/phosphorylation state of hundreds of key signaling proteins and protein pathways in sun-protected skin after an acute dose of two minimal erythema dose (MED) of SSL. RPPA analysis was used to map the altered cell signaling networks resulting from acute doses of solar simulated radiation (SSL). To that end, we exposed sun-protected skin in volunteers to acute doses of two MED of SSL and collected biopsies pre-SSL and post-SSL irradiation. Frozen biopsies were subjected to laser capture microdissection (LCM) and then assessed by RPPA. The activation/phosphorylation or total levels of 128 key signaling proteins and drug targets were selected for statistical analysis. Coordinate network-based analysis was performed on specific signaling pathways that included the PI3k/Akt/mTOR and Ras/Raf/MEK/ERK pathways. Overall, we found early and sustained activation of the PI3K-AKT-mTOR and MAPK pathways. Cell death and apoptosis-related proteins were activated at 5 and 24 h. Ultimately, expression profile patterns of phosphorylated proteins in the epidermal growth factor receptor (EGFR), AKT, mTOR, and other relevant pathways may be used to determine pharmacodynamic activity of new and selective topical chemoprevention agents administered in a test area exposed to SSL to determine drug-induced attenuation or reversal of skin carcinogenesis pathways.
- Gao, G., Zhang, T., Wang, Q., Reddy, K., Chen, H., Yao, K., Wang, K., Roh, E., Zykova, T., Ma, W., Ryu, J., Curiel-Lewandrowski, C., Alberts, D., Dickinson, S. E., Bode, A. M., Xing, Y., & Dong, Z. (2017). ADA-07 Suppresses Solar Ultraviolet-Induced Skin Carcinogenesis by Directly Inhibiting TOPK. Molecular cancer therapeutics, 16(9), 1843-1854.More infoCumulative exposure to solar ultraviolet (SUV) irradiation is regarded as the major etiologic factor in the development of skin cancer. The activation of the MAPK cascades occurs rapidly and is vital in the regulation of SUV-induced cellular responses. The T-LAK cell-originated protein kinase (TOPK), an upstream activator of MAPKs, is heavily involved in inflammation, DNA damage, and tumor development. However, the chemopreventive and therapeutic effects of specific TOPK inhibitors in SUV-induced skin cancer have not yet been elucidated. In the current study, ADA-07, a novel TOPK inhibitor, was synthesized and characterized. Pull-down assay results, ATP competition, and in vitro kinase assay data revealed that ADA-07 interacted with TOPK at the ATP-binding pocket and inhibited its kinase activity. Western blot analysis showed that ADA-07 suppressed SUV-induced phosphorylation of ERK1/2, p38, and JNKs and subsequently inhibited AP-1 activity. Importantly, topical treatment with ADA-07 dramatically attenuated tumor incidence, multiplicity, and volume in SKH-1 hairless mice exposed to chronic SUV. Our findings suggest that ADA-07 is a promising chemopreventive or potential therapeutic agent against SUV-induced skin carcinogenesis that acts by specifically targeting TOPK. Mol Cancer Ther; 16(9); 1843-54. ©2017 AACR.
- Dickinson, D., Janda, D., Criswell, D., Blohm-Mangone, D., Olson, D., Liu, D., Barber, D., Rusche, D., Petricoin, D., Calvert, D., Einspahr, D., Dickinson, D., Stratton, D., Curiel-Lewandrowski, D., Saboda, D., Hu, D., Bode, D., Dong, D., Alberts, D., & Bowden, D. (2016). Inhibition of Akt Enhances the Chemopreventive Effects of Topical Rapamycin in Mouse Skin. Cancer prevention research (Philadelphia, Pa.).More infoThe PI3Kinase/Akt/mTOR pathway has important roles in cancer development for multiple tumor types, including UV-induced non-melanoma skin cancer. Immunosuppressed populations are at increased risk of aggressive cutaneous squamous cell carcinoma (SCC). Individuals who are treated with rapamycin, (sirolimus, a classical mTOR inhibitor) have significantly decreased rates of developing new cutaneous SCCs compared to those that receive traditional immunosuppression. However, systemic rapamycin use can lead to significant adverse events. Here we explored the use of topical rapamycin as a chemopreventive agent in the context of solar simulated light (SSL)-induced skin carcinogenesis. In SKH-1 mice, topical rapamycin treatment decreased tumor yields when applied after completion of 15 weeks of SSL exposure compared to controls. However, applying rapamycin during SSL exposure for 15 weeks, and continuing for 10 weeks after UV treatment, increased tumor yields. We also examined whether a combinatorial approach might result in more significant tumor suppression by rapamycin. We validated that rapamycin causes increased Akt (S473) phosphorylation in the epidermis after SSL, and show for the first time that this dysregulation can be inhibited in vivo by a selective PDK1/Akt inhibitor, PHT-427. Combining rapamycin with PHT-427 on tumor prone skin additively caused a significant reduction of tumor multiplicity compared to vehicle controls. Our findings indicate that patients taking rapamycin should avoid sun exposure, and that combining topical mTOR inhibitors and Akt inhibitors may be a viable chemoprevention option for individuals at high risk for cutaneous SCC.
- Janda, J., Burkett, N. B., Blohm-Mangone, K., Huang, V., Curiel-Lewandrowski, C., Alberts, D. S., Petricoin, E. F., Calvert, V. S., Einspahr, J., Dong, Z., Bode, A. M., Wondrak, G. T., & Dickinson, S. E. (2016). Resatorvid-based Pharmacological Antagonism of Cutaneous TLR4 Blocks UV-induced NF-κB and AP-1 Signaling in Keratinocytes and Mouse Skin. Photochemistry and photobiology, 92(6), 816-825.More infoCutaneous exposure to solar ultraviolet (UV) radiation is a major causative factor in skin carcinogenesis, and improved molecular strategies for efficacious chemoprevention of nonmelanoma skin cancer (NMSC) are urgently needed. Toll-like receptor 4 (TLR4) signaling has been shown to drive skin inflammation, photoimmunosuppression, and chemical carcinogenesis. Here we have examined the feasibility of genetic and pharmacological antagonism targeting cutaneous TLR4 for the suppression of UV-induced NF-κB and AP-1 signaling in keratinocytes and mouse skin. Using immunohistochemical and proteomic microarray analysis of human skin, we demonstrate for the first time that a significant increase in expression of TLR4 occurs in keratinocytes during the progression from normal skin to actinic keratosis, also detectible during further progression to squamous cell carcinoma. Next, we demonstrate that siRNA-based genetic TLR4 inhibition blocks UV-induced stress signaling in cultured keratinocytes. Importantly, we observed that resatorvid (TAK-242), a molecularly targeted clinical TLR4 antagonist, blocks UV-induced NF-κB and MAP kinase/AP-1 activity and cytokine expression (Il-6, Il-8, and Il-10) in cultured keratinocytes and in topically treated murine skin. Taken together, our data reveal that pharmacological TLR4 antagonism can suppress UV-induced cutaneous signaling, and future experiments will explore the potential of TLR4-directed strategies for prevention of NMSC.
- Bermudez, Y., Stratton, S. P., Curiel-Lewandrowski, C., Warneke, J., Hu, C., Bowden, G. T., Dickinson, S. E., Dong, Z., Bode, A. M., Saboda, K., Brooks, C. A., Petricoin, E. F., Hurst, C. A., Alberts, D. S., & Einspahr, J. G. (2015). Activation of the PI3K/Akt/mTOR and MAPK Signaling Pathways in Response to Acute Solar-Simulated Light Exposure of Human Skin. Cancer prevention research (Philadelphia, Pa.), 8(8), 720-8.More infoThe incidence of skin cancer is higher than all other cancers and continues to increase, with an average annual cost over $8 billion in the United States. As a result, identifying molecular pathway alterations that occur with UV exposure to strategize more effective preventive and therapeutic approaches is essential. To that end, we evaluated phosphorylation of proteins within the PI3K/Akt and MAPK pathways by immunohistochemistry in sun-protected skin after acute doses of physiologically relevant solar-simulated ultraviolet light (SSL) in 24 volunteers. Biopsies were performed at baseline, 5 minutes, 1, 5, and 24 hours after SSL irradiation. Within the PI3K/Akt pathway, we found activation of Akt (serine 473) to be significantly increased at 5 hours while mTOR (serine 2448) was strongly activated early and was sustained over 24 hours after SSL. Downstream, we observed a marked and sustained increase in phospho-S6 (serine 235/S236), whereas phospho-4E-BP1 (threonines 37/46) was increased only at 24 hours. Within the MAPK pathway, SSL-induced expression of phospho-p38 (threonine 180/tyrosine 182) peaked at 1 to 5 hours. ERK 1/2 was observed to be immediate and sustained after SSL irradiation. Phosphorylation of histone H3 (serine 10), a core structural protein of the nucleosome, peaked at 5 hours after SSL irradiation. The expression of both p53 and COX-2 was increased at 5 hours and was maximal at 24 hours after SSL irradiation. Apoptosis was significantly increased at 24 hours as expected and indicative of a sunburn-type response to SSL. Understanding the timing of key protein expression changes in response to SSL will aid in development of mechanistic-based approaches for the prevention and control of skin cancers.
- Dickinson, S. E., Rusche, J. J., Bec, S. L., Horn, D. J., Janda, J., Rim, S. H., Smith, C. L., & Bowden, G. T. (2015). The effect of sulforaphane on histone deacetylase activity in keratinocytes: Differences between in vitro and in vivo analyses. Molecular carcinogenesis, 54(11), 1513-20.More infoSulforaphane is a natural product found in broccoli, which is known to exert many different molecular effects in the cell, including inhibition of histone deacetylase (HDAC) enzymes. Here, we examine for the first time the potential for sulforaphane to inhibit HDACs in HaCaT keratinocytes and compare our results with those found using HCT116 colon cancer cells. Significant inhibition of HDAC activity in HCT116 nuclear extracts required prolonged exposure to sulforaphane in the presence of serum. Under the same conditions HaCaT nuclear extracts did not exhibit reduced HDAC activity with sulforaphane treatment. Both cell types displayed down-regulation of HDAC protein levels by sulforaphane treatment. Despite these reductions in HDAC family member protein levels, acetylation of marker proteins (acetylated Histone H3, H4, and tubulin) was decreased by sulforaphane treatment. Time-course analysis revealed that HDAC6, HDAC3, and acetylated histone H3 protein levels are significantly inhibited as early as 6 h into sulforaphane treatment. Transcript levels of HDAC6 are also suppressed after 48 h of treatment. These results suggest that HDAC activity noted in nuclear extracts is not always translated as expected to target protein acetylation patterns, despite dramatic inhibition of some HDAC protein levels. In addition, our data suggest that keratinocytes are at least partially resistant to the nuclear HDAC inhibitory effects of sulforaphane, which is exhibited in HCT116 and other cells.
- Kim, J., Roh, E., Lee, M. H., Yu, D. H., Kim, D. J., Lim, T., Jung, S. K., Peng, C., Cho, Y., Dickinson, S., Alberts, D., Bowden, G. T., Einspahr, J., Stratton, S. P., Curiel-Lewandrowski, C., Bode, A. M., Lee, K. W., & Dong, Z. (2015). Fyn is a redox sensor involved in solar ultraviolet light-induced signal transduction in skin carcinogenesis. Oncogene.More infoSolar ultraviolet (UV) light is a major etiological factor in skin carcinogenesis, with solar UV-stimulated signal transduction inducing pathological changes and skin damage. The primary sensor of solar UV-induced cellular signaling has not been identified. We use an experimental system of solar simulated light (SSL) to mimic solar UV and we demonstrate that Fyn is a primary redox sensor involved in SSL-induced signal transduction. Reactive oxygen species (ROS) generated by SSL exposure directly oxidize Cys488 of Fyn, resulting in increased Fyn kinase activity. Fyn oxidation was increased in mouse skin after SSL exposure and Fyn-knockout mice formed larger and more tumors compared with Fyn wild-type mice when exposed to SSL for an extended period of time. Murine embryonic fibroblasts (MEFs) lacking Fyn and cells in which Fyn expression was knocked down were resistant to SSL-induced apoptosis. Furthermore, cells expressing mutant Fyn (C448A) were resistant to SSL-induced apoptosis. These findings suggest that Fyn acts as a regulatory nexus between solar UV, ROS and signal transduction during skin carcinogenesis.Oncogene advance online publication, 21 December 2015; doi:10.1038/onc.2015.471.
- Lee, M., Lim, D. o., Kim, D., Lee, D., Shin, D., Kim, D., Kim, D., Kim, D., Jung, D., Yao, D., Kundu, D., Lee, D., Lee, D., Dickinson, D., Alberts, D., Bowden, D., Stratton, D., Curiel, D., Einspahr, D., , Bode, D., et al. (2015). Genetic ablation of caspase-7 promotes solar-simulated light-induced mouse skin carcinogenesis: the involvement of keratin-17. Carcinogenesis, 36(11), 1372-80.More infoSolar ultraviolet irradiation is an environmental carcinogen that causes skin cancer. Caspase-7 is reportedly expressed at reduced levels in many cancers. The present study was designed to examine the role of caspase-7 in solar-simulated light (SSL)-induced skin cancer and to elucidate its underlying molecular mechanisms. Our study revealed that mice with genetic deficiency of caspase-7 are highly susceptible to SSL-induced skin carcinogenesis. Epidermal hyperplasia, tumor volume and the average number of tumors were significantly increased in caspase-7 knockout (KO) mice compared with SKH1 wild-type mice irradiated with SSL. The expression of cell proliferation markers, such as survivin and Ki-67, was elevated in SSL-irradiated skin of caspase-7 KO mice compared with those observed in SSL-exposed wild-type SKH1 mouse skin. Moreover, SSL-induced apoptosis was abolished in skin from caspase-7 KO mice. Two-dimensional gel electrophoresis, followed by matrix-assisted laser desorption/ionization-time-of-flight analysis of skin tissue lysates from SSL-irradiated SKH1 wild-type and caspase-7 KO mice revealed an aberrant induction of keratin-17 in caspase-7 KO mice. Immunohistochemical analysis of skin tumors also showed an increase of keratin-17 expression in caspase-7 KO mice compared with SKH1 wild-type mice. The expression of keratin-17 was also elevated in SSL-irradiated caspase-7 KO keratinocytes as well as in human basal cell carcinomas. The in vitro caspase activity assay showed keratin-17 as a substrate of caspase-7, but not caspase-3. Overall, our study demonstrates that genetic loss of caspase-7 promotes SSL-induced skin carcinogenesis by blocking caspase-7-mediated cleavage of keratin-17.
- Dickinson, S. E., Olson, E. R., Levenson, C., Janda, J., Rusche, J. J., Alberts, D. S., & Bowden, G. T. (2014). A novel chemopreventive mechanism for a traditional medicine: East Indian sandalwood oil induces autophagy and cell death in proliferating keratinocytes. Archives of biochemistry and biophysics, 558, 143-52.More infoOne of the primary components of the East Indian sandalwood oil (EISO) is α-santalol, a molecule that has been investigated for its potential use as a chemopreventive agent in skin cancer. Although there is some evidence that α-santalol could be an effective chemopreventive agent, to date, purified EISO has not been extensively investigated even though it is widely used in cultures around the world for its health benefits as well as for its fragrance and as a cosmetic. In the current study, we show for the first time that EISO-treatment of HaCaT keratinocytes results in a blockade of cell cycle progression as well as a concentration-dependent inhibition of UV-induced AP-1 activity, two major cellular effects known to drive skin carcinogenesis. Unlike many chemopreventive agents, these effects were not mediated through an inhibition of signaling upstream of AP-1, as EISO treatment did not inhibit UV-induced Akt or MAPK activity. Low concentrations of EISO were found to induce HaCaT cell death, although not through apoptosis as annexin V and PARP cleavage were not found to increase with EISO treatment. However, plasma membrane integrity was severely compromised in EISO-treated cells, which may have led to cleavage of LC3 and the induction of autophagy. These effects were more pronounced in cells stimulated to proliferate with bovine pituitary extract and EGF prior to receiving EISO. Together, these effects suggest that EISO may exert beneficial effects upon skin, reducing the likelihood of promotion of pre-cancerous cells to actinic keratosis (AK) and skin cancer.
- Franklin, S. J., Dickinson, S. E., Karlage, K. L., Bowden, G. T., & Myrdal, P. B. (2014). Stability of sulforaphane for topical formulation. Drug development and industrial pharmacy, 40(4), 494-502.More infoSulforaphane (SFN) is a natural compound that has been investigated as a chemopreventive agent. SFN has been shown to inhibit the activator-protein-1 (AP-1) transcription factor and may be effective for inhibition of ultraviolet (UV) induced skin carcinogenesis. This study was designed to investigate the stability of SFN as a function of pH, temperature and in various solvents and formulations.
- Morrissy, S., Strom, J., Purdom-Dickinson, S., & Chen, Q. M. (2012). NAD(P)H:quinone oxidoreductase 1 is induced by progesterone in cardiomyocytes. Cardiovascular toxicology, 12(2), 108-14.More infoNAD(P)H: quinone oxidoreductase 1 (NQO1) is a ubiquitous flavoenzyme that catalyzes two-electron reduction of various quinones by utilizing NAD(P)H as an electron donor. Our previous study found that progesterone (PG) can protect cardiomyocytes from apoptosis induced by doxorubicin (Dox). Microarray analyses of genes induced by PG had led to the discovery of induction of NQO1 mRNA. We report here that PG induces NQO1 protein and its activity in a dose-dependent manner. Whereas NQO1 is well known as a target gene of Nrf2 transcription factor due to the presence of antioxidant response element (ARE) in the promoter, PG did not activate the ARE, suggesting Nrf2-independent induction of NQO1. To address the role of NQO1 induction in PG-induced cytoprotection, we tested the effect of NQO1 inducer β-naphthoflavone and inhibitor dicoumarol. Induction of NQO1 by β-naphthoflavone decreased Dox-induced apoptosis and potentiated the protective effect of PG as measured by caspase-3 activity. PG-induced NQO1 activity was inhibited with dicoumarol, which did not affect PG-induced cytoprotection. Dicoumarol treatment alone potentiated Dox-induced caspase-3 activity. These data suggest that while NQO1 plays a role in PG-induced cytoprotection, there are additional components contributing to PG-induced cytoprotection.
- Dickinson, S. E., Olson, E. R., Zhang, J., Cooper, S. J., Melton, T., Criswell, P. J., Casanova, A., Dong, Z., Hu, C., Saboda, K., Jacobs, E. T., Alberts, D. S., & Bowden, G. T. (2011). p38 MAP kinase plays a functional role in UVB-induced mouse skin carcinogenesis. Molecular carcinogenesis, 50(6), 469-78.More infoUVB irradiation of epidermal keratinocytes results in the activation of the p38 mitogen-activated protein kinase (MAPK) pathway and subsequently activator protein-1 (AP-1) transcription factor activation and cyclooxygenase-2 (COX-2) expression. AP-1 and COX-2 have been shown to play functional roles in UVB-induced mouse skin carcinogenesis. In this study, the experimental approach was to express a dominant negative p38α MAPK (p38DN) in the epidermis of SKH-1 hairless mice and assess UVB-induced AP-1 activation, COX-2 expression, and the skin carcinogenesis response in these mice compared to wild-type littermates. We observed a significant inhibition of UVB-induced AP-1 activation and COX-2 expression in p38DN transgenic mice, leading to a significant reduction of UVB-induced tumor number and growth compared to wild-type littermates in a chronic UVB skin carcinogenesis model. A potential mechanism for this reduction in tumor number and growth rate is an inhibition of chronic epidermal proliferation, observed as reduced Ki-67 staining in p38DN mice compared to wild-type. Although we detected no difference in chronic apoptotic rates between transgenic and nontransgenic mice, analysis of acutely irradiated mice demonstrated that expression of the p38DN transgene significantly inhibited UVB-induced apoptosis of keratinocytes. These results counter the concerns that inhibition of p38 MAPK in a chronic situation could compromise the ability of the skin to eliminate potentially tumorigenic cells. Our data indicate that p38 MAPK is a good target for pharmacological intervention for UV-induced skin cancer in patients with sun damaged skin, and suggest that inhibition of p38 signaling reduces skin carcinogenesis by inhibiting COX-2 expression and proliferation of UVB-irradiated cells.
- Chandramouli, A., Mercado-Pimentel, M. E., Hutchinson, A., Gibadulinová, A., Olson, E. R., Dickinson, S., Shañas, R., Davenport, J., Owens, J., Bhattacharyya, A. K., Regan, J. W., Pastorekova, S., Arumugam, T., Logsdon, C. D., & Nelson, M. A. (2010). The induction of S100p expression by the Prostaglandin E₂ (PGE₂)/EP4 receptor signaling pathway in colon cancer cells. Cancer biology & therapy, 10(10), 1056-66.More infoProstaglandin E₂ (PGE₂) levels are frequently elevated in colorectal carcinomas. PGE₂ is perceived via four transmembrane G protein coupled receptors (EP1-4), among which the EP4 receptor is most relevant. PGE₂/EP4-receptor interaction activates CREB via the ERK/MEK pathway. However, the downstream target genes activated by this pathway remained to be investigated.
- Olson, E. R., Melton, T., Dickinson, S. E., Dong, Z., Alberts, D. S., & Bowden, G. T. (2010). Quercetin potentiates UVB-Induced c-Fos expression: implications for its use as a chemopreventive agent. Cancer prevention research (Philadelphia, Pa.), 3(7), 876-84.More infoQuercetin (Qu) is currently being investigated as a chemopreventive agent for several cancers, including nonmelanoma skin cancer induced by UV light. We previously reported that Qu degradation has important consequences on signaling and cell biology. In the current study, we report that Qu induces c-Fos mRNA and protein expression through activation of p38 and cAMP-responsive element binding protein (CREB), and Qu potentiates UVB-induced c-Fos expression. Inclusion of ascorbic acid (AA) in cell culture medium stabilizes Qu and completely prevents both Qu- and UVB-induced p38 and CREB activation, leading to a blockade of c-fos gene expression through reduced CREB/cAMP-responsive element binding. AA stabilizes c-Fos mRNA, increasing steady-state levels even when c-fos gene expression is suppressed, but this has no effect on c-Fos protein levels in either mock- or UVB-irradiated cells. We report that Qu blocks mammalian target of rapamycin signaling and inhibits c-Fos protein expression directly through this mechanism because cotreatment with Qu and AA resulted in the complete suppression of UVB-induced c-Fos protein expression even in the presence of significantly increased mRNA levels. We further confirmed that this was not due to increased protein turnover because inhibition of proteasome activity with MG-132 did not raise c-Fos protein levels in Qu+AA-treated cells. Together, these data indicate that although Qu has been reported to have some beneficial properties as a chemopreventive agent, it is also capable of inducing c-fos expression, a cellular event important for the promotion phase of tumor development, if it is not stabilized.
- Vrba, L., Jensen, T. J., Garbe, J. C., Heimark, R. L., Cress, A. E., Dickinson, S., Stampfer, M. R., & Futscher, B. W. (2010). Role for DNA methylation in the regulation of miR-200c and miR-141 expression in normal and cancer cells. PloS one, 5(1), e8697.More infoThe microRNA-200 family participates in the maintenance of an epithelial phenotype and loss of its expression can result in epithelial to mesenchymal transition (EMT). Furthermore, the loss of expression of miR-200 family members is linked to an aggressive cancer phenotype. Regulation of the miR-200 family expression in normal and cancer cells is not fully understood.
- Dickinson, S. E., Melton, T. F., Olson, E. R., Zhang, J., Saboda, K., & Bowden, G. T. (2009). Inhibition of activator protein-1 by sulforaphane involves interaction with cysteine in the cFos DNA-binding domain: implications for chemoprevention of UVB-induced skin cancer. Cancer research, 69(17), 7103-10.More infoSulforaphane is an isothiocyanate derived from cruciferous vegetables that has been linked to decreased risk of certain cancers. Although the role of sulforaphane in the induction of the transcription factor Nrf2 has been studied extensively, there is also evidence that inhibition of the transcription factor activator protein-1 (AP-1) may contribute to the chemopreventive properties of this compound. In this study, we show for the first time that sulforaphane is effective at reducing the multiplicity and tumor burden of UVB-induced squamous cell carcinoma in a mouse model using cotreatment with the compound and the carcinogen. We also show that sulforaphane pretreatment is able to reduce the activity of AP-1 luciferase in the skin of transgenic mice after UVB. Chromatin immunoprecipitation analysis verified that a main constituent of the AP-1 dimer, cFos, is inhibited from binding to the AP-1 DNA binding site by sulforaphane. Electrophoretic mobility shift assay analysis of nuclear proteins also shows that sulforaphane and diamide, both known to react with cysteine amino acids, are effective at inhibiting AP-1 from binding to its response element. Using truncated recombinant cFos and cJun, we show that mutation of critical cysteines in the DNA-binding domain of these proteins (Cys(154) in cFos and Cys(272) in cJun) results in loss of sensitivity to both sulforaphane and diamide in electrophoretic mobility shift assay analysis. Together, these data indicate that inhibition of AP-1 activity may be an important molecular mechanism in chemoprevention of squamous cell carcinoma by sulforaphane.
- Purdom-Dickinson, S. E., Lin, Y., Dedek, M., Morrissy, S., Johnson, J., & Chen, Q. M. (2007). Induction of antioxidant and detoxification response by oxidants in cardiomyocytes: evidence from gene expression profiling and activation of Nrf2 transcription factor. Journal of molecular and cellular cardiology, 42(1), 159-76.More infoMild or low doses of oxidants are known to prime cells towards resistance against further damage. In cardiomyocytes, we found that pretreatment with 100 microM H(2)O(2) prevents the cells from apoptosis induced by doxorubicin (Dox). Affymetrix microarray analyses of 28,000 genes reveal that H(2)O(2) treated cells reduced expression of genes encoding cytochrome c, mitochondrial complex I, III, IV and V and several contractile proteins. Elevated expression of antioxidant and detoxification genes appears as a dominant feature of the gene expression profile of H(2)O(2) treated cells. Most of the genes in this category contain an Antioxidant Response Element (ARE) in their promoters. Measurements of ARE promoter-reporter gene activity indicate a dose- and time-dependent activation of the ARE by H(2)O(2). Since the Nrf2 transcription factor regulates ARE-mediated gene expression, we overexpressed Nrf2 to test whether activation of Nrf2 is sufficient to induce cytoprotection. High levels of Nrf2 expression were achieved via adenovirus mediated gene delivery. Transduced Nrf2 was present in the nuclei and caused an increase in the expression of NAD(P)H:quinone oxidoreductase 1 (NQO1), a representative downstream target of Nrf2. Unlike H(2)O(2) pretreated cells, the cells expressing high levels of Nrf2 were not resistant to Dox-induced apoptosis. Therefore, the cytoprotective effect of H(2)O(2) pretreatment is not reliant upon Nrf2 activation alone as measured by resistance against Dox-induced apoptosis.
- Purdom-Dickinson, S. E., Sheveleva, E. V., Sun, H., & Chen, Q. M. (2007). Translational control of nrf2 protein in activation of antioxidant response by oxidants. Molecular pharmacology, 72(4), 1074-81.More infoNf-E2 related factor-2 (Nrf2) is a basic leucine zipper transcription factor that binds and activates the antioxidant response element (ARE) in the promoters of many antioxidant and detoxification genes. We found that H(2)O(2) treatment caused a rapid increase in endogenous Nrf2 protein level in rat cardiomyocytes. Semiquantitative or real-time reverse transcription-polymerase chain reaction failed to show an increase of Nrf2 mRNA level by H(2)O(2) treatment. Measurements of Nrf2 protein stability excluded the possibility of Nrf2 protein stabilization. Although inhibiting protein synthesis with cycloheximide prevented H(2)O(2) from elevating Nrf2 protein level, RNA synthesis inhibition with actinomycin D failed to do so. Measurements of new protein synthesis with [(35)S]methionine incorporation confirmed that H(2)O(2) increased the translation of Nrf2 protein. Inhibitors of phosphoinositide 3-kinase were able to abolish the induction of Nrf2 protein by H(2)O(2). Although H(2)O(2) increased phosphorylation of p70 S6 kinase, rapamycin failed to inhibit H(2)O(2) from elevating Nrf2 protein. H(2)O(2) also induced phosphorylation of eukaryotic translation initiation factor (eIF) 4E and eIF2alpha within 30 and 10 min, respectively. Inhibiting eIF4E with small interfering siRNA or increasing eIF2alpha phosphorylation with salubrinal did not affect Nrf2 elevation by H(2)O(2). Our data present a novel phenomenon of quick onset of the antioxidant/detoxification response via increased translation of Nrf2 by oxidants. The mechanism underlying such stress-induced de novo protein translation may involve multiple components of translational machinery.
- Chen, Q. M., Alexander, D., Sun, H., Xie, L., Lin, Y., Terrand, J., Morrissy, S., & Purdom, S. (2005). Corticosteroids inhibit cell death induced by doxorubicin in cardiomyocytes: induction of antiapoptosis, antioxidant, and detoxification genes. Molecular pharmacology, 67(6), 1861-73.More infoPsychological or physical stress induces an elevation of corticosteroids in the circulating system. We report here that corticosterone (CT) protects cardiomyocytes from apoptotic cell death induced by doxorubicin (Dox), an antineoplastic drug known to induce cardiomyopathy possibly through reactive oxygen species production. The cytoprotection induced by CT is within the range of physiologically relevant doses. The lowest dose tested, 0.1 microM (or 3.5 microg/dl), inhibited apoptosis by approximately 25% as determined by caspase activity. With 1 microM CT, cardiomyocytes gain a cytoprotective effect after 8 h of incubation and remain protected for at least 72 h. Hydrocortisone, cortisone, dexamethasone, and aldosterone but not androstenedione or cholesterol also induced cytoprotection. Analyses of 20,000 gene expression sequences using Affymetrix high-density oligonucleotide array found that CT caused up-regulation of 140 genes and down-regulation of 108 genes over 1.5-fold. Among the up-regulated genes are bcl-xL, metallothioneins, glutathione peroxidase-3, and glutathione S-transferases. Western blot analyses revealed that CT induced an elevation of bcl-xL but not bcl-2 or proapoptotic factors bax, bak, and bad. Inhibiting the expression of bcl-xL reduced the cytoprotective effect of CT. Our data suggest that CT induces a cytoprotective effect on cardiomyocytes in association with reprogramming gene expression and induction of bcl-xL gene.
- Purdom, S., & Chen, Q. M. (2005). Epidermal growth factor receptor-dependent and -independent pathways in hydrogen peroxide-induced mitogen-activated protein kinase activation in cardiomyocytes and heart fibroblasts. The Journal of pharmacology and experimental therapeutics, 312(3), 1179-86.More infoMild doses of oxidative stress in the heart correlate with the induction of apoptosis or hypertrophy in cardiomyocytes (CMCs) and fibrosis or proliferation of fibroblasts. Three branches of mitogen-activated protein kinases (MAPKs), i.e., c-Jun N-terminal kinases (JNKs), extracellular signal-related kinases 1 and 2 (ERK1/2), and p38, are activated by oxidants in a variety of cell types, including CMCs. However, the initiation process of these signaling pathways remains unsolved. We explored the role of the epidermal growth factor (EGF) receptor in H(2)O(2)-induced MAPK activation using two different cell types from the same organ: CMCs and heart fibroblasts (HFs). Pretreatment of each cell type with EGF revealed differences in how CMCs and HFs responded to subsequent treatment with H(2)O(2): in CMCs, the second treatment resulted in little further activation of JNKs and ERK1/2, whereas HFs retained the full response of JNKs and ERK1/2 activation by H(2)O(2) regardless of EGF pretreatment. AG-1478 [4-(3'-chloroanilino)-6,7-dimethoxy-quinazoline], a pharmacologic inhibitor of the EGF receptor tyrosine kinase, inhibited JNK and ERK1/2 activations but not p38 in both cell types. The data using the Src inhibitor PP2 [4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine] resemble those found when using AG-1478 in either cell type. Pharmacologic inhibitors of matrix metalloproteinases (MMPs) further illustrated the difference between the two cell types. In HFs, MMP inhibitors GM6001 [N-[(2R)-2-(hydroxamidocarbonylmethyl)-4-methylpentanoyl]-l-tryptophan methylamide] and BB2516 [[2S-[N4(R(*)),2R(*),3S(*)]]-N4-[2,2-dimethyl-1-[(methylamino)carbonyl]propyl]-N1,2-dihydroxy-3-(2-methylpropyl)butanediamide, marimastat] inhibited JNKs and ERK1/2 activation without affecting p38 activation by H(2)O(2) inhibitors. In contrast, these MMP failed to significantly inhibit the activation of JNKs, ERKs, or p38 in CMCs. These data suggest the complexity of the cell type-dependent signaling web initiated by oxidants in the heart.
- Purdom, S., & Chen, Q. M. (2003). Linking oxidative stress and genetics of aging with p66Shc signaling and forkhead transcription factors. Biogerontology, 4(4), 181-91.More infoGenetics versus oxidative stress have been long-standing points of contention among theories seeking to explain the root of aging. Because aging is the highest risk factor for many diseases, it is to our advantage to better understand the biological mechanisms of this process. Caloric restriction has been the only reliable means of extending lifespan in mammalian models until recently. The discovery of mutant strains of mice with increased longevity could be a significant contributor to our understanding of the genetic and molecular basis of human aging. One genetic approach that increases the longevity of mice is the removal of the p66Shc gene, which encodes a protein belonging to a family of adaptors for signal transduction in mitogenic and apoptotic responses. Normally, p66Shc is tyrosine phosphorylated (activated) by various extracellular signals including EGF and insulin. However, serine phosphorylation of p66Shc can occur after oxidative stress either in association with or independently of tyrosine phosphorylation. p66Shc serine phosphorylation has been linked to inactivation of members of forkhead transcription factors, resulting in increased intracellular oxidant levels and increased sensitivity to apoptosis. Knocking out p66Shc allows moderately elevated activity of forkhead transcription factors and better-equipped antioxidant defenses at the cellular level. Recent reports have suggested that methylation of the p66Shc promoter has important implications in its expression regulation. This leads us to hypothesize that the methylation status of the p66Shc promoter may differ between individuals and therefore contribute to variations of longevity. We present evidence arguing that decreasing oxidative stress or increasing resistance to oxidative damage as a result of genetic variation or p66Shc knockout is likely contributing to individual differences in longevity.
- Purdom, S., & Chen, Q. M. (2003). p66(Shc): at the crossroad of oxidative stress and the genetics of aging. Trends in molecular medicine, 9(5), 206-10.More infoThe biology of aging has been mysterious for centuries. Removal of the p66(Shc) gene, which encodes an adaptor protein for cell signaling, extends lifespan by approximately 30% in mice and confers resistance to oxidative stress. The absence of p66(Shc) correlates with reduced levels of apoptosis. Oxidants induce phosphorylation of serine36 on p66(Shc), contributing to inactivation of members of the Forkhead transcription factor family, some of which appear to regulate the expression of antioxidant genes. The expression of p66(Shc) is regulated by the methylation status of its promoter. This leads us to hypothesize that increased methylation of the p66(Shc) promoter might contribute to the absence of its expression and therefore extended longevity in particular individuals.
- Chen, Q. M., Merrett, J. B., Dilley, T., & Purdom, S. (2002). Down regulation of p53 with HPV E6 delays and modifies cell death in oxidant response of human diploid fibroblasts: an apoptosis-like cell death associated with mitosis. Oncogene, 21(34), 5313-24.More infoThe tumor suppressor p53 protein is known to play a critical role in apoptosis. In normal human diploid fibroblasts (HDFs), expression of the human papillomaviral (HPV) E6 gene results in a reduction of p53 protein and an inhibition of oxidant induced apoptosis within 24 h. In comparison, expression of the HPV E7 gene causes down-regulation of Rb protein without inhibiting apoptosis. Here we determine whether HDFs expressing E6 undergo cell death with a delayed time course following H2O2 exposure. Appearances of caspase-3 activity, cell detachment, trypan blue uptake and aberrant nuclei were all delayed in E6 cells compared to wild type (wt) or E7 cells. A mutant E6 gene that failed to reduce p53 could not delay cell death. Morphological examination revealed nuclear condensation in dying wt or E7 cells but nuclear fragmentation in E6 cells. Flow cytometry analysis indicated an S phase distribution of dying wt or E7 cells but a G2/M phase distribution of dying E6 cells. An elevation of cyclin B was observed in dying E6 cells but not in apoptotic E7 cells. Dying E6 cells also had elevated levels of cdc-2 protein and histone kinase activity, suggesting that the cells died at mitosis. Electron microscopy studies showed that E6 cells may die at prophase or prometaphase. Overexpression of bcl-2 resulted in an inhibition of both caspase-3 and death of E7 or E6 cells. Inactivating caspases with zVAD-fmk also reduced the death rate of E7 and E6 cells. Our data indicate that expression of HPV E6 causes a delay and morphological modification of cell death induced by oxidants. E6 cells die at mitosis, which can be inhibited by bcl-2 overexpression or caspase inhibition.
- Casibang, M., Purdom, S., Jakowlew, S., Neckers, L., Zia, F., Ben-Av, P., Hla, T., You, L., Jablons, D. M., & Moody, T. W. (2001). Prostaglandin E2 and vasoactive intestinal peptide increase vascular endothelial cell growth factor mRNAs in lung cancer cells. Lung cancer (Amsterdam, Netherlands), 31(2-3), 203-12.More infoThe effects of prostaglandin E2 (PGE2) and vasoactive intestinal peptide (VIP) on vascular endothelial cell growth factor (VEGF) mRNAs were investigated using lung cancer cells. By RT-PCR, VEGF(121), VEGF(165), and VEGF(189), but not VEGF(206) isoforms were detected in all lung cancer cell lines and biopsy specimens examined. By Northern blot, VEGF mRNA was detected in all small cell lung cancer (SCLC) and non-SCLC (NSCLC) cell lines examined. PGE2, VIP and forskolin caused increased VEGF expression in a time- and concentration-dependent manner using NSCLC cell line NCI-H157. Approximately 1 microM PGE2, 0.1 microM VIP and 50 microM forskolin caused cAMP elevation, 64-, 33- and 128-fold, respectively, using NCI-H157 cells after 5 min. The increase in cAMP caused by PGE(2) and VIP was reversed by somatostatin (SST). Also 1 microM PGE2, 0.1 microM VIP and 50 microM forskolin increased the VEGF mRNA 2.0-, 1.5- and 2.3-fold, respectively, after 4 h. The increase in VEGF mRNA caused by PGE2, VIP and forskolin was inhibited by H-89, a protein kinase A inhibitor. A VIP receptor antagonist, VIPhybrid, inhibited the increase in cAMP and VEGF mRNA caused by VIP. By ELISA, VEGF was detected in the conditioned media exposed to the lung cancer cell lines. These results suggest that VEGF synthesis in and secretion from lung cancer cells can be regulated by agents, which cause adenylyl cyclase activation.
- Chen, Q. M., Prowse, K. R., Tu, V. C., Purdom, S., & Linskens, M. H. (2001). Uncoupling the senescent phenotype from telomere shortening in hydrogen peroxide-treated fibroblasts. Experimental cell research, 265(2), 294-303.More infoNormal human cells have a limited replicative potential and inevitably reach replicative senescence in culture. Replicatively senescent cells show multiple molecular changes, some of which are related to the irreversible growth arrest in culture, whereas others resemble the changes occurring during the process of aging in vivo. Telomeres shorten as a result of cell replication and are thought to serve as a replicometer for senescence. Recent studies show that young cells can be induced to develop features of senescence prematurely by damaging agents, chromatin remodeling, and overexpression of ras or the E2F1 gene. Accelerated telomere shortening is thought to be a mechanism of premature senescence in some models. In this work, we test whether the acquisition of a senescent phenotype after mild-dose hydrogen peroxide (H(2)O(2)) exposure requires telomere shortening. Treating young HDFs with 150 microM H(2)O(2) once or 75 microM H(2)O(2) twice in 2 weeks causes long-term growth arrest, an enlarged morphology, activation of senescence-associated beta-galactosidase, and elevated expression of collagenase and clusterin mRNAs. No significant telomere shortening was observed with H(2)O(2) at doses ranging from 50 to 200 microM. Weekly treatment with 75 microM H(2)O(2) also failed to induce significant telomere shortening. Failure of telomere shortening correlated with an inability to elevate p16 protein or mRNA in H(2)O(2)-treated cells. In contrast, p21 mRNA was elevated over 40-fold and remained at this level for at least 2 weeks after a pulse treatment of H(2)O(2). The role of cell cycle checkpoints centered on p21 in premature senescence induced by H(2)O(2) is discussed here.
- Chen, Q. M., Tu, V. C., Purdon, S., Wood, J., & Dilley, T. (2001). Molecular mechanisms of cardiac hypertrophy induced by toxicants. Cardiovascular toxicology, 1(4), 267-83.More infoCardiac hypertrophy is an end point of chronic cardiac toxicity from a number of toxicants. Doxorubicin, cocaine, acetaldehyde, monocrotaline, and azide are examples of these toxicants, which may induce hypertrophy by increasing oxidants, circulating levels of catecholamines, and hemodynamic load or by inducing hypoxia. We summarize here the major signal transduction pathways and common changes in gene expression found with the classical hypertrophy inducers angiotensin II, endothelin 1, and catecholamines. Activation of G-proteins, calcium signaling, phosphoinositide 3-kinase (PI3K), certain family members of protein kinase Cs (PKCs), and three branches of mitogenactivated protein kinases (MAPKs), i.e. extracellular signal-regulated kinases (ERKs), p38, and c-Jun N-terminal kinases (JNKs), are important for developing a hypertrophic phenotype in cardiomyocytes. Characteristic changes of gene expression in hypertrophy include the elevated transcription of atrial natriuretic factor (ANF), beta-myosin heavy chain (beta MHC), skeletal alpha-actin (SkA), certain variants of integrins and perhaps tubulin genes, and reduced expression of the sarcoplasmic reticulum proteins phospholamban and sarco(endo)plasmic reticulum Ca2+-ATPase 2 alpha (SERCA2 alpha), and of the ryanodine receptors. Although which toxicants induce these molecular changes remains to be tested, increasing lines of evidence support that oxidants play a central role in cardiac hypertrophy. Oxidants activate small G-proteins, calcium signaling, PI3K, PKCs, and MAPKs. Oxidants cause cardiomyocytes to enlarge in vitro. Recent developments in transgenic, genomic, and proteomic technologies will provide needed tools to reveal the mechanism of chronic cardiac toxicity at the cellular and molecular levels.
- Weber, H. C., Walters, J., Leyton, J., Casibang, M., Purdom, S., Jensen, R. T., Coy, D. H., Ellis, C., Clark, G., & Moody, T. W. (2001). A bombesin receptor subtype-3 peptide increases nuclear oncogene expression in a MEK-1 dependent manner in human lung cancer cells. European journal of pharmacology, 412(1), 13-20.More infoA synthetic peptide, (D-Phe(6), beta-Ala(11), Phe(13), Nle(14))bombesin-(6-14) was used to investigate the signal transduction mechanisms of bombesin receptor subtype-3. Using NCI-1299#5 human lung cancer cells stably transfected with bombesin receptor subtype-3, 100 nM (D-Phe(6), beta-Ala(11), Phe(13), Nle(14))bombesin-(6-14) elevated the cytosolic Ca2+ from 150 to 250 nM within 10 s. Addition of (D-Phe(6), beta-Ala(11), Phe(13), Nle(14))bombesin-(6-14) caused phosphorylation of mitogen activated protein kinase in a time- and concentration-dependent manner. The mitogen activated protein kinase phosphorylation caused by (D-Phe(6), beta-Ala(11), Phe(13), Nle(14))bombesin-(6-14) was inhibited by 2'-amino-3'-methyoxyflavone (PD98059), a mitogen activated protein kinase kinase (MEK-1) inhibitor. Using a luciferase reporter gene construct, (D-Phe(6), beta-Ala(11), Phe(13), Nle(14))bombesin-(6-14) caused Elk-1 activation after 10 min and the increase in Elk-1 activation caused by (D-Phe(6), beta-Ala(11), Phe(13), Nle(14))bombesin-(6-14) was inhibited by PD98059 as well as a dominant-negative MEK-1. (D-Phe(6), beta-Ala(11), Phe(13), Nle(14))bombesin-(6-14) caused increased c-fos as well as c-jun mRNAs 1 h after addition to NCI-H1299#5 cells. The 47-fold increase in c-fos mRNA caused by 100 nM (D-Phe(6), beta-Ala(11), Phe(13), Nle(14))bombesin-(6-14) was inhibited by PD98059, a dominant-negative MEK-1 and a substance P antagonist but not (3-phenylpropanoyl-D-Ala(24), Pro(26), Psi(26,27), Phe(27))GRP-(20-27) (BW2258U89), a GRP receptor antagonist. These results indicate that (D-Phe(6), beta-Ala(11), Phe(13), Nle(14))bombesin-(6-14) caused increased nuclear oncogene expression and upstream events include mitogen activated protein kinase phosphorylation and Elk-1 activation.
- Leyton, J., Gozes, Y., Pisegna, J., Coy, D., Purdom, S., Casibang, M., Zia, F., & Moody, T. W. (1999). PACAP(6-38) is a PACAP receptor antagonist for breast cancer cells. Breast cancer research and treatment, 56(2), 177-86.More infoThe effects of pituitary adenylate cyclase activating polypeptide (PACAP) analogs were investigated using breast cancer cells. 125I-PACAP-27 bound with high affinity (Kd = 5 nM) to T47D cells (Bmax = 29,000 per cell). Specific 125I-PACAP-27 binding was inhibited half maximally by PACAP-27, PACAP-38, PACAP(6-38) and PACAP(28-38) with IC50) values of 8, 17, 750 and >3000 nM, respectively. By RT-PCR, PACAP receptor mRNA was present in MCF-7 and T47D cell lines. Polyclonal antibodies to a PACAP receptor fragment (A-8-C) were elicited. The antibodies were affinity purified, recognized a 60-kDa protein by western blot, and stained malignant cells in breast cancer biopsy specimens by immunohistochemistry. PACAP-27 elevated the cAMP in T47D cells and the increase in cAMP caused by PACAP was inhibited by PACAP(6-38). PACAP-27 stimulated c-fos mRNA in T47D cells and the increase in c-fos gene expression caused by PACAP was reversed by PACAP(6-38). PACAP(6-38) inhibited colony formation using a soft agar assay and inhibited breast cancer xenograft growth in nude mice. These data suggest that PACAP(6-38) functions as a breast cancer PACAP receptor antagonist.
- Dickinson, S. E. (2021, August). Exploring the roles of keratinocytic inflammatory mediators as targets for prevention and biomarkers of risk in non-melanoma skin cancer. Cancer Center Grand Rounds. University of Arizona.
- Dickinson, S. E. (2021, May). Characterization of PD-L1 in skin after acute UV irradiation and during progression to cSCC. American Society for Photobiology Symposium. Virtual.
- Wondrak, G. T., & Dickinson, S. E. (2021, September). Topical Prevention of Skin Photocarcinogenesis: Targeting Toll-like Receptor 4 (TLR4) and Beyond. Translational Advances in Cancer Prevention Agent Development (TACPAD) Virtual Workshop on Immunomodulatory Agents. Virtual: Division of Cancer Prevention, National Cancer Institute.
- Dickinson, S. E. (2020, Febrary 10, 2020). New tools and new focus for Project 1 of the Skin Cancer Program Project Grant: The plan to move Resatorvid into topical clinical trials for skin cancer prevention.. Cancer Prevention and Control Seminar Series. University of Arizona.
- Dickinson, S. E., Krutzsch, M., Yozwiak, M., Saboda, K., Roe, D., Petricoin, E., Calvert, V., & Curiel, C. N. (2019, Spring). Increased PD-L1 expression in human skin acutely and chronically exposed to UV irradiation.. Society for Investigational Dermatology. Chicago, IL.
- Dickinson, S. E. (2018, October). Translational Skin Cancer Prevention Research at the University of Arizona and the Targeting of Toll-like Receptor 4. Biomolecular Sciences Graduate Programs Seminar Series. Boise, ID: Boise State University.
- Dickinson, S. E. (2018, September). Blocking Non-Melanoma Skin Cancer by Regulating Inflammatory Signaling in Keratinocytes: Targeting Toll-like Receptor 4. Cancer Prevention and Control Seminar Series. Tucson, AZ.
- Dickinson, S. E. (2015, February 25). Targeting the PI3-Kinase/AKT/mTOR Signaling Pathway for the Chemoprevention of Solar UV-Induced Skin Cancer. Scientific Advisory Board Meeting for the Chemoprevention of Skin Cancer Program Project. University of Arizona.
- Kirschnerova V, V., Vaishampayan, P., Khawam, M., Curiel, C. N., Wondrak, G. T., & Dickinson, S. E. (2021, April). TLR4 expression as a determinant of EMT and stress response gene expression in UV exposed human keratinocytes.. AACR Annual Meeting. Virtual.
- Kirschnerova, V., Vaishampayan, P., & Dickinson, S. E. (2021, May). PD-L1 Induction in Keratinocytes after Acute UV Exposure. 14th International Skin Carcinogenesis Conference. Virtual.
- Dickinson, S. E. (2020, May, 2020). CrispR/Cas9 deletion of TLR4 impacts the UV-induced stress response in human keratinocytes.. Society for Investigative Dermatology Annual Conference. Virtual due to COVID-19.
- Curiel, C. N., Krutzsch, M., Yozwiak, M., Saboda, K., Roe, D., & Dickinson, S. E. (2019, Spring). Increased PD-L1 and CD47 expression in high-risk cutaneous squamous cell carcinomas.. Society for Investigational Dermatology Conference. Chicago, IL.
- Dickinson, S. E. (2018, October). A novel strategy for topical photochemoprevention: Pharmacological TLR4 antagonism blocks non-melanoma skin cancer.. 13th International Skin Carcinogenesis Conference, Austin, TX. Austin, TX.
- Dickinson, S. E., & Curiel-Lewandrowski, C. (2017, April). A novel strategy for topical photochemoprevention: Pharmacological TLR4 antagonism blocks non-melanoma skin cancer. 76th Annual Meeting Society of Investigative Dermatology.
- Dickinson, S. E., & Curiel-Lewandrowski, C. (2017, April). Pharmacological TLR4 antagonism using topical resatorvid blocks solar UV-induced skin tumorigenesis in SKH-1 mice. American Association of Cancer Research. Washington, DC.
- Dickinson, S. E. (2017, April). A novel strategy for topical photochemoprevention: Pharmacological TLR4 antagonism blocks non-melanoma skin cancer.. Soc. Invest. Derm., Portland, OR.
- Dickinson, S. E. (2017, April). Pharmacological TLR4 antagonism using topical resatorvid blocks solar UV-induced skin tumorigenesis in SKH-1 mice.. Proc. AACR, Washington D.C..
- Janda, J., Blohm-Mangone, K., Burkett, N., Einspahr, J. G., Alberts, D. S., Dong, Z., Bode, A. M., Curiel, C. N., Wondrak, G. T., & Dickinson, S. E. (2016, May). TLR4 as a novel molecular target for non-melanoma skin cancer prevention.. Soc. Invest. Derm. #85,.More infoAbstract for poster presented at a conference.
- Dickinson, S. E. (2015, April). Paradoxical activity of topical Rapamycin in UV-induced murine non-melanoma skin cancer.. Proc. AACR, Philadelphia, PA, 2015..
- Dickinson, S. E., & Taylor, M. (2015, April). Sulforaphane potentiates non-melanoma skin cancer in UVB-treated Nrf2 knockout mice.. Proc. AACR, Philadelphia, PA, 2015..