Role of SIRT3 in melanoma development and progression

黑色素瘤是最致命的皮肤癌之一，由黑素细胞产生，黑素细胞负责 黑色素的产生。对黑色素瘤生物学认识的最新进展导致了 有希望的靶向治疗。例如，BRAF抑制剂vemurafenib和dabrafenib实现了 与化疗相比有显着改善，并被批准用于 BRAF 治疗转移性黑色素瘤 突变。最近，达拉非尼与 MEK 抑制剂曲美替尼 (Trametinib) 的组合显示出改善 与单一疗法相比，无进展生存期，并已获得美国 FDA 的批准。然而， 即使采用联合治疗，大多数患者也会产生获得性耐药，从而无法治愈 实现持久的肿瘤消退。因此，管理需要新的基于目标的方法 黑色素瘤。哺乳动物 Sirtuins 构成了一个由七个已知成员组成的家族 (SIRT1 – SIRT7) 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着关键作用， 并被证明参与多种疾病的发病机制，包括癌症。 SIRT 的作用 癌症中的功能极其复杂，并且根据细胞环境的不同，它们似乎具有二分功能。 在已知的 SIRT 中，SIRT3 是一种线粒体去乙酰化酶，可协调线粒体活性的整体变化 通过使参与多种线粒体功能的蛋白质脱乙酰化。它还在其中发挥着重要作用 调节多种细胞过程，包括转录、胰岛素分泌和细胞凋亡。事实 SIRT3 可以调节对癌细胞增殖至关重要的多种细胞过程，使其成为 癌症管理的潜在治疗靶点。虽然SIRT3在癌症中的作用研究仍在进行中 在其起步阶段，研究表明其具有抑癌和促癌作用。然而，角色 SIRT3 在黑色素瘤中的作用尚不清楚。在我们的初步数据中，我们发现 SIRT3 在 黑色素瘤及其抑制导致黑色素瘤细胞显着的抗增殖反应。此外，我们 我们还发现 4'-溴白藜芦醇 (4BR) 是一种新的 SIRT3 小分子抑制剂，具有抗- 人类黑色素瘤细胞的增殖作用。因此，根据现有文献和我们的初步数据，我们 提议检验 SIRT3 通过调节在黑色素瘤进展中发挥关键作用的假设 p53 信号传导、Ku70-Bax 相互作用和/或细胞代谢稳态。具体目标如下 建议：1) o 使用组织定义 SIRT3 在黑色素瘤发生和进展中的作用 由退伍军人的回顾性黑色素瘤组织和体外细胞创建的微阵列（TMA） 转型模型； 2) 定义p53信号传导、Ku70-Bax相互作用、细胞代谢的参与 稳态，作为黑色素瘤细胞中 SIRT3 的下游决定因素； 3) 确定治疗方案 1) Braf-Pten 小鼠黑色素瘤模式和患者来源的异种移植物中 SIRT3 体内抑制的意义 （PDX）是用从退伍军人身上前瞻性收集的转移性黑色素瘤组织开发的。我们期望 本申请中提出的研究结果可能会定义 SIRT3 在 黑素细胞转化和黑素瘤进展。这可能最终导致小说的发展 黑色素瘤的诊断、预后或治疗方法。由于黑色素瘤的发病率似乎 退伍军人群体中的比例较高，我们提出的研究旨在确定其分子机制 黑色素瘤的发展可能会导致确定治疗这种致命性黑色素瘤的新策略 肿瘤。因此，我们提出的工作对于退伍军人和军人的医疗保健具有相关性和重要意义。 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.