Role of UDP-Glucuronosyltransferases in UV-mediated melanomagenesis

描述（由申请人提供）：黑色素细胞对保护皮肤免受紫外线辐射的有害影响至关重要。矛盾的是，黑素细胞是最致命的皮肤癌黑色素瘤的前身。黑色素瘤是美国增长最快的肿瘤类型之一，在过去的20年里，世界范围内的病例数量翻了一番。黑色素瘤是一种极具侵袭性的肿瘤，对目前的治疗方法具有令人难以置信的抵抗力。如果早期发现黑色素瘤，在肿瘤侵袭之前，它可以通过手术切除治愈。不幸的是，黑色素瘤病变可能在很长一段时间内无法识别或无症状。因此，鉴定信息丰富的生物标志物和分子靶点，用于化学预防黑色素瘤的进展，对于控制这种致命疾病至关重要。这一建议建立在以下新观察的基础上：三种ugt （UGT2B7、UGT2B10和UGT2B15）在人类黑色素细胞中正常表达，但在黑色素瘤进展过程中它们的表达丢失。由于UGT是细胞对抗癌症形成的自然防御机制的重要组成部分，我们假设UGT表达的缺失是黑色素瘤进展所必需的。该提案的重点是阐明在使用人体组织的黑色素瘤进展过程中，ugt是否以及何时丢失，以及这种丢失如何导致黑色素细胞变成黑色素瘤。这里提出的证据表明，长期以来被认为与黑色素瘤的因果作用有关的紫外线辐射下调了黑色素细胞中UGT的表达。这一观察结果将进一步表征，以阐明UV-A和UV-B是否都触发了UGT表达的减少，以及这种减少是否与UGT整体活性的丧失相关。该提案还将研究UGT活性在黑色素瘤进展中的作用。由于UGT2B7、UGT2B10和UGT2B15都能使生物活性脂质12-羟基二碳四烯酸（12-HETE）失活，并且12-HETE水平升高与黑色素瘤的进展有关，我们假设人类黑色素瘤是由不受控制的12-HETE信号通路通过UGT表达的丧失而驱动的。为了验证这一点，UGT2B7、UGT2B10和UGT2B15将在转移性黑色素瘤细胞中稳定过表达，并监测12-HETE的水平，并将其与细胞增殖、凋亡和侵袭性的变化联系起来。相反，shRNA将被用来抑制原发性黑色素瘤细胞中UGT的表达，通过检查这些细胞的生长、避免凋亡的能力和增加的侵袭性来观察这些细胞是否进展到更具侵袭性的黑色素瘤阶段。这些结果也将与12-HETE和12-HETE-葡糖苷水平相关。这里提出的研究结果将增强我们对黑色素瘤进展的理解，并确定新的信息生物标志物以及治疗干预这种致命疾病的新靶点。

DESCRIPTION (provided by applicant): Melanocytes are essential to protecting the skin from the harmful effects of UV radiation. Paradoxically, melanocytes are the precursors of the most deadly form of skin cancer, melanoma. Melanoma is one of the fastest growing tumor types in the United States and the number of cases worldwide has doubled in the past 20 years. Melanoma is an extremely aggressive tumor and incredibly resistant to current therapies. If melanoma is detected early, before the tumor becomes invasive, it can be cured through surgical resection. Unfortunately, melanoma lesions can remain unidentifiable or asymptomatic for long periods of time. Therefore, the identification of informative biomarkers and molecular targets for the chemoprevention of melanoma progression is vital to the control of this deadly disease. This proposal builds on the novel observation that three UGTs (UGT2B7, UGT2B10 and UGT2B15) are normally expressed in human melanocytes and that their expression is lost during melanoma progression. Since the UGTs are a vital part of the cells natural defense mechanisms against cancer formation, we hypothesize that loss of UGT expression is required for melanoma progression. This proposal is focused on elucidating if and when UGTs are lost during melanoma progression in using human tissues and how that loss may cause melanocytes to become melanoma. Evidence presented here show that UV radiation, which has long been implicated in a causal role for melanoma, downregulates UGT expression in melanocytes. This observation will be further characterized to elucidate if both UV-A and UV-B triggers reduction of UGT expression and if that reduction correlates to a loss of overall UGT activity. This proposal will also investigate the role of UGT activity in melanoma progression. Since UGT2B7, UGT2B10 and UGT2B15 all can inactivate the bioactive lipid 12-hydroxyeicosatetraenoic acid (12-HETE) and elevated 12-HETE levels have been correlated to melanoma progression, we hypothesize that human melanoma is driven by uncontrolled 12-HETE signaling through loss of UGT expression. To test this, UGT2B7, UGT2B10 and UGT2B15 will be stably overexpressed in metastatic melanoma cells and the levels of 12-HETE will be monitored and correlated with alterations in cell proliferation, apoptosis and invasiveness Conversely, shRNA will be used to knockdown UGT expression in primary melanoma cells to see if those cells progress to more aggressive melanoma stages by examining their growth, ability to avoid apoptosis and increased invasiveness. These results will also be correlated to 12-HETE and 12-HETE-glucuronide levels. Results from the studies proposed here will enhance our understanding of melanoma progression and identify new informative biomarkers as well as novel targets for therapeutic intervention of this deadly disease. PUBLIC HEALTH RELEVANCE: This project will examine if human melanoma progression is driven by uncontrolled bioactive lipid signaling. The role of UV radiation in enabling this uncontrolled bioactive lipid signaling will also be examined as will the role of the UGTs (enzymes responsible for turning off lipid signaling). These studies are the first to examine UGTs in melanoma progression. If successful, this grant will enhance our understanding of melanoma etiology, provide informative biomarkers of melanoma progression and identify novel targets for therapeutic intervention of this deadly disease.