Targeting Rheostatic Mechanisms of Melanoma Progression

皮肤黑色素瘤具有很高的致命性，在美国最常见的癌症中排名第五。 老年人，但老年人，年轻人，甚至儿童都会受到影响。在所有癌症类型中，黑色素瘤是 在极早期转移的倾向上是最具侵袭性的之一。转移性黑色素瘤很难 迫切需要根除和新的治疗方法来限制疾病的发展。黑色素瘤的遗传原因 沿着RAS蛋白信号的连续体排列，其中BRAFV600E突变是最常见的驱动因素。这个 突变的BRAFV600E蛋白依赖于MAPK信号通路来启动和维持肿瘤生长。 用RAF和MEK抑制剂靶向这一异常激活的通路在治疗上的成功有限 本病因MAPK信号重新激活，引起耐药性。因此，更机械化的见解是 以开发能够规避耐药性的联合疗法。我们报告了这一异常情况 激活小GTP酶ARF6，一种控制细胞内转运的蛋白质，加速肿瘤的转移 BRAFV600E黑色素瘤。在转移之前，我们未发表的数据显示，ARF6蛋白也是 BRAFV600E黑色素瘤小鼠的高效肿瘤发展和生长。这将ARF6定位为关键字 在疾病进展的多个时间点进行调节。事实上，我们的初步数据表明了ARF6的一个新角色 通过调节激活的磷酸化ERK的核定位在MAPK信号转导中，磷酸化ERK是MAPK信号转导的关键效应蛋白 布拉夫。因此，我们假设ARF6调控BRAFV600E介导的肿瘤进展，控制MAPK 传递信号并为药物抑制肿瘤生长和转移提供一个脆弱的节点。 使用遗传和药理学方法，包括我们独特的小鼠模型和特定的ARF6抑制剂 我们的目标是剖析ARF6在MAPK信号转导中的作用，发现新的角色(S) ARF6在肿瘤细胞功能中的作用，并检测ARF6抑制剂抑制肿瘤进展的效果。根据 这些目标，我们将：1)测试ARF6控制BRAFV600E-黑色素瘤MAPK信号的假设；2)测试 ARF6对BRAFV600E黑色素瘤的增殖和生存至关重要的假说；3)检验该假说 ARF6的药理抑制对BRAFV600E黑色素瘤患者的治疗效果 异种移植(MPDX)。成功完成本提案中的目标将确定新的机制 黑色素瘤进展可接受治疗干预，并可能使ARF6成为潜在的 RAS基因突变癌症的治疗靶点。

Cutaneous melanoma is highly lethal and the fifth most common cancer in the U.S. Peak incidence is in middle age adults but the elderly, young adults and even children are affected. Among all cancer types, melanoma is one of the most aggressive in its propensity for extremely early metastasis. Metastatic melanoma is difficult to eradicate and new therapies are urgently needed to limit disease progression. Genetic causes of melanoma align along a continuum of RAS protein signaling whereby BRAFV600E mutation is the most common driver. The mutant BRAFV600E protein depends on MAPK signaling for both initiation and maintenance of tumor growth. Targeting this abnormally-activated pathway with RAF and MEK inhibitors have had limited success in treating this disease due to MAPK signaling reactivation, causing drug resistance. Thus, more mechanistic insights are needed in order to develop combination therapies that can circumvent resistance. We reported that aberrant activation of the small GTPase ARF6, a protein that controls intracellular trafficking, accelerates metastasis of BRAFV600E melanoma. Prior to metastasis, our unpublished data reveal that the protein ARF6 is also required for efficient tumor development and growth in mice with BRAFV600E melanoma. This positions ARF6 as a key regulator at multiple points in disease progression. Indeed, our preliminary data suggest a novel role for ARF6 in MAPK signaling by regulating the nuclear localization of activated, phospho-ERK, a key effector protein for BRAF. Thus, we hypothesize that ARF6 modulates BRAFV600E-mediated tumor progression, controlling MAPK signaling and providing a vulnerable node for pharmacologic inhibition of both tumor growth and metastasis. Using genetic and pharmacologic approaches, including our unique mouse models and a specific ARF6 inhibitor that we helped develop, our goals are to dissect the roles of ARF6 in MAPK signaling, discover new role(s) for ARF6 in tumor cell function, and test the efficacy of ARF6 inhibitors in restricting tumor progression. Pursuant to these goals, we will: 1) Test the hypothesis that ARF6 controls MAPK signaling in BRAFV600E-melanoma; 2) Test the hypothesis that ARF6 is critical for proliferation and survival of BRAFV600E melanoma; 3) Test the hypothesis that pharmacologic inhibition of ARF6 has therapeutic efficacy in BRAFV600E melanoma patient-derived xenografts (MPDX). Successful completion of the aims in this proposal will identify new mechanisms of melanoma progression that are amenable to therapeutic intervention and may position ARF6 as a potential therapeutic target in RAS-mutant cancers.