Targeting Oncogenic BRAF And PI3'-Kinase Signaling For Melanoma Therapy

描述（由申请人提供）：黑色素瘤因其发病率的惊人增加而闻名，尤其是在年轻人中，其攻击性临床行为和致命性转移的倾向，表明迫切需要针对该疾病的新治疗策略。尽管临床和流行病学情况黯淡，但遗传分析发现了黑色素瘤的关键驱动癌基因，例如突变激活的 BRAF。事实上，当 BRAFV600E 癌蛋白被维莫非尼从药理学上抑制时，BRAF 突变的黑色素瘤患者，即使是那些患有广泛播散性转移性疾病的患者，也能享受到肿瘤的显着消退以及健康状况的显着改善。然而，由于并非所有 BRAF 突变黑色素瘤患者都对维莫非尼有反应，而且即使有反应，通常会因致命的耐药性疾病而复发，因此黑色素瘤治疗的范式正在朝着针对 BRAFV600E 的通路靶向抑制剂和协同信号模块（例如 PI3'-激酶->AKT 通路）的合理靶向组合发展。事实上，尽管维莫非尼在临床上取得了成功，而且我们对黑色素瘤细胞内部运作的科学知识不断增长，但挑战仍然是如何最好地利用 BRAF 抑制剂进行黑色素瘤治疗，以： 1. 最大限度地提高治疗效果； 2. 最大限度地减少致命耐药性疾病的出现；和; 3. 减轻潜在的有害副作用。因此，本研究的长期总体目标是设计基于 BRAF 抑制剂的联合疗法，与 UCSF 黑色素瘤诊所的同事合作，提高总体缓解率和每位患者主要抗肿瘤反应的深度，并无限期延长 BRAF 突变黑色素瘤患者的缓解持续时间。为了实现这些目标，该提案的短期目标是采用最先进的基因工程小鼠（GEM）模型、真正的人类黑色素瘤细胞和一系列临床相关的通路靶向抑制剂来阐明 BRAFV600E/PI3'-激酶通路在黑色素瘤发生中合作的分子机制以及临床前环境中联合通路靶向阻断的后果。在目标 1 中，GEM 模型将用于探讨 PI3'-激酶->AKT 信号传导在与致癌 BRAFV600E 合作将正常黑色素细胞转化为转移性黑色素瘤细胞中的重要性。在目标 2 中，将使用 BRAFV600E 引发的黑色素瘤的 GEM 模型来评估 BRAFV600E 或 PI3'-激酶的联合抑制与单药抑制在促进肿瘤消退方面的优越性。为了补充目标 2 中对小鼠黑色素瘤标本的分析，目标 3 将采用一组真正的人 BRAFV600E 表达黑色素瘤细胞系，以阐明 BRAFV600E 与 PI3'-激酶 ->AKT 信号传导合作，通过影响蛋白质合成来调节黑色素瘤细胞分裂周期和/或细胞凋亡的分子机制。完成后，这些研究将为开发稳健、合理、靶向途径的联合治疗策略提供机制基础，以提高 BRAF 突变黑色素瘤患者的生活数量和质量。

DESCRIPTION (provided by applicant): Melanoma is noted for its alarming increase in incidence, especially amongst the young, aggressive clinical behavior and propensity for lethal metastasis, illustrating an urgent need for new treatment strategies for this disease. Despite the bleak clinical and epidemiological picture, genetic analysis has uncovered key driver oncogenes in melanoma such as mutationally activated BRAF. Indeed, when the BRAFV600E oncoprotein is pharmacologically inhibited with vemurafenib, BRAF mutated melanoma patients, even those with widely disseminated, metastatic disease, have enjoyed dramatic tumor regression coupled with significant health improvement. However, since not all BRAF mutated melanoma patients respond to vemurafenib and, those that do, generally relapse with lethal drug resistant disease, the paradigm of melanoma therapy is evolving towards rationally-targeted combinations of pathway-targeted inhibitors acting against BRAFV600E and cooperating signaling modules such as the PI3'-kinase->AKT pathway. Indeed, despite vemurafenib's clinical success and our growing scientific knowledge of the melanoma cell's inner workings, the challenge remains how best to employ BRAF inhibitors for melanoma therapy to: 1. Maximize therapeutic benefit; 2. Minimize emergence of lethal drug resistant disease; and; 3. Mitigate potentially harmful side effects. Consequently, the long-term, overarching goal of this research is to design BRAF inhibitor-based combination therapies that enhance the overall response rate and the depth of each patient's primary anti-tumor response and extend indefinitely the duration of remission of patients with BRAF mutated melanoma in collaboration with colleagues in the UCSF Melanoma Clinic. Towards these goals, the short-term aims of this proposal are to employ state-of-the-art genetically engineered mouse (GEM) models, bona fide human melanoma cells and a portfolio of clinically relevant pathway-targeted inhibitors to elucidate the molecular mechanism(s) of BRAFV600E/PI3'- kinase pathway cooperation in melanomagenesis and the consequences of combined pathway-targeted blockade in the pre-clinical setting. In Aim 1, GEM models will be used to probe the importance of PI3'- kinase->AKT signaling in cooperating with oncogenic BRAFV600E in converting normal melanocytes to metastatic melanoma cells. In Aim 2 the superiority of combined versus single agent inhibition of BRAFV600E or PI3'-kinase in promoting tumor regression will be evaluated using GEM models of BRAFV600E-initiated melanoma. To complement analysis of mouse melanoma specimens in Aim 2, a panel of bona fide human BRAFV600E expressing melanoma cell lines will be employed in Aim 3 to elucidate molecular mechanism(s) by which BRAFV600E cooperates with PI3'-kinase->AKT signaling in regulating the melanoma cell division cycle and/or apoptosis through effects on protein synthesis. When completed, these studies will provide the mechanistic foundation for the development of robust and rational, pathway-targeted combination therapeutic strategies to increase both the quantity and quality of life of patients with BRAF mutated melanoma.