Role of SIRT3 in melanoma development and progression

黑色素瘤是最致命的皮肤癌之一，由黑色素细胞引起， 黑色素生成。最近对黑色素瘤生物学理解的进展导致了 有希望的靶向治疗。例如，BRAF抑制剂维罗非尼和达拉菲尼实现了 与化疗相比有显著改善，并被批准用于转移性黑色素瘤与BRAF- 突变最近，达拉非尼与MEK抑制剂曲美替尼的组合显示出改善的 无进展生存期，并已获得美国FDA的批准。然而，在这方面， 即使采用联合治疗，大多数患者也会产生获得性耐药性， 实现持久的肿瘤消退。因此，需要新的基于目标的管理方法 黑色素瘤哺乳动物sirtuins构成一个由七个已知成员（SIRT 1-SIRT 7）组成的家族， NAD+依赖性蛋白脱乙酰酶和/或ADP-核糖基转移酶活性]。此外，他们还 已知调节翻译后酰基修饰。SIRT在重要的细胞过程中发挥关键作用， 并显示与包括癌症在内的多种疾病的发病机制有关。SIRT的作用 在癌症中是极其复杂的，并且它们似乎具有取决于细胞环境的二分功能。 在已知的SIRTs中，SIRT 3是一种线粒体sirtuin，其协调线粒体活性的整体转移 通过脱乙酰化参与多种线粒体功能的蛋白质。它也发挥着重要作用， 调节多种细胞过程，包括转录、胰岛素分泌和凋亡。的事实 SIRT 3可以调节几种在癌细胞增殖中至关重要的细胞过程，使其成为一种 癌症管理的潜在治疗靶点。虽然SIRT 3在癌症中的作用的研究仍在进行中， 在早期，研究表明它具有肿瘤抑制和肿瘤促进作用。然而， SIRT 3在黑色素瘤中的作用尚不清楚。在我们的初步数据中，我们已经发现SIRT 3在小鼠中过表达。 黑色素瘤及其抑制导致黑色素瘤细胞中显著的抗增殖反应。我们还 他们还发现，4 '-溴-白藜芦醇（4 BR），一种新的SIRT 3小分子抑制剂， 在人黑素瘤细胞中的增殖作用。因此，根据现有文献和我们的初步数据，我们 我建议检验SIRT 3通过调节黑色素瘤的进展而在黑色素瘤进展中起关键作用的假设。 p53信号传导、Ku 70-Bax相互作用和/或细胞代谢稳态。以下具体目标 提出：1）确定SIRT 3在黑色素瘤发展和进展中的作用，采用组织化学方法， 微阵列（TMA）从退伍军人患者的回顾性黑色素瘤组织和体外细胞中创建 2）确定p53信号转导、Ku 70-Bax相互作用、细胞代谢、细胞凋亡和细胞凋亡的参与。 稳态，作为黑色素瘤细胞中SIRT 3的下游决定因素;和3）确定治疗性免疫抑制剂。 在1）Braf-Pten小鼠黑色素瘤模式和患者来源异种移植物中体内SIRT 3抑制的意义 (PDX)从退伍军人患者中前瞻性收集转移性黑色素瘤组织。我们预计 本申请中提出的研究结果可以定义SIRT 3在以下方面的作用和机制： 黑素细胞转化和黑色素瘤进展。这可能最终导致小说的发展 用于黑素瘤的诊断、预后或治疗方法。由于黑色素瘤的发病率似乎 在退伍军人群体中更高，我们提出的研究旨在确定 黑色素瘤的发展可能导致确定新的战略，管理这一致命的 肿瘤。因此，我们提出的工作对退伍军人的医疗保健具有重要意义， 符合退伍军人事务部的使命。

Melanoma, one of the deadliest cancer of skin, arises from melanocytic cells that are responsible for melanin production. Recent advances in the understanding of melanoma biology has led to the development of targeted therapies with promise. For example, BRAF inhibitors vemurafenib and dabrafenib achieved significant improvement over chemotherapy and were approved for metastatic melanomas with BRAF- mutations. More recently, the combination of dabrafenib with MEK inhibitor trametinib demonstrated improved progression-free survival, compared to monotherapy, and has received approval from the US FDA. However, even with the combination treatment, most of the patients develop acquired resistance, thereby failing to achieve lasting tumor regression. Therefore, novel target-based approaches are needed for the management of melanomas. The mammalian sirtuins constitute a family of seven known members (SIRT1 – SIRT7) with NAD+-dependent protein deacetylase and/or ADP-ribosyltransferase activities]. In addition, they are also known to regulate post-translational acyl modifications. SIRTs play critical roles in important cellular processes, and are shown to be involved in the pathogenesis of a variety of diseases, including cancer. The role of SIRTs in cancer is extremely complex and they appears to have dichotomous functions depending on cell contexts. Among known SIRTs, SIRT3 is a mitochondrial sirtuin, which coordinates global shift in mitochondrial activity by deacetylating proteins involved in diverse mitochondrial functions. It also plays important roles in the regulation of a variety of cellular processes, including transcription, insulin secretion, and apoptosis. The fact that SIRT3 can regulate several cellular processes which are critical in cancer cell proliferation, makes it a potential therapeutic target for cancer management. While the research on the role of SIRT3 in cancer is still in its infancy, studies have suggested its tumor suppressor as well as tumor promoter roles. However, the role of SIRT3 in melanoma is not known. In our preliminary data, we have found that SIRT3 is overexpressed in melanoma and its inhibition results in a significant anti-proliferative response in melanoma cells. Further, we have also found that 4'-bromo-resveratrol (4BR), a new small molecule inhibitor of SIRT3, imparts anti- proliferative effects in human melanoma cells. Thus, based on available literature and our preliminary data, we propose to test the hypothesis that SIRT3 plays a critical role in melanoma progression via modulating p53 signaling, Ku70-Bax interaction and/or cellular metabolic homeostasis. The following specific aims are proposed: 1) o define the role of SIRT3 in melanoma development and progression, employing a tissue microarray (TMA) created from retrospective melanoma tissues from veteran patients, and an in vitro cell transformation model; 2) to define the involvement of p53 signaling, Ku70-Bax interaction, cellular metabolic homeostasis, as downstream determinants of SIRT3 in melanoma cells; and 3) to determine the therapeutic significance of SIRT3 inhibition in vivo in 1) Braf-Pten mouse melanoma mode, and patient derived xenografts (PDX) developed with prospectively collected metastatic melanoma tissues from veteran patients. We expect that the outcome of studies proposed in this application may define the role and mechanism of SIRT3 in melanocytic transformation and melanoma progression. This may ultimately lead to development of novel diagnostic, prognostic or therapeutic approaches for melanoma. Since melanoma incidence seems to be higher in the veteran population and our proposed study aimed at defining the molecular mechanism of melanoma development may lead to identification of novel strategies for the management of this deadly neoplasm. Therefore, our proposed work is relevant and significant to the health care of Veterans and is in line with the mission of the Department of Veteran Affairs.