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

描述（申请人提供）：黑色素瘤以其惊人的发病率增加而著称，特别是在年轻人中，具有侵略性的临床行为和致命转移的倾向，表明迫切需要新的治疗策略来治疗这种疾病。尽管临床和流行病学情况黯淡，遗传分析已经发现了黑色素瘤的关键驱动癌基因，如突变激活的BRAF。事实上，当vemurafenib在药理学上抑制BRAFV600E癌蛋白时，BRAF突变的黑色素瘤患者，即使是那些广泛传播的转移性疾病患者，也能享受到显著的肿瘤消退和显著的健康改善。然而，由于并非所有BRAF突变的黑色素瘤患者都对vemurafenib有反应，而那些对vemurafenib有反应的患者通常会复发并出现致命的耐药疾病，因此黑色素瘤治疗的范式正朝着合理靶向的途径靶向抑制剂联合作用于BRAFV600E和协同信号模块（如PI3'-激酶->AKT通路）的方向发展。事实上，尽管vemurafenib在临床取得了成功，我们对黑色素瘤细胞内部运作的科学知识也在不断增长，但挑战仍然是如何最好地将BRAF抑制剂用于黑色素瘤治疗：使治疗效益最大化；2. 尽量减少致命耐药疾病的出现；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与UCSF黑色素瘤诊所的同事合作，设计基于BRAF抑制剂的联合疗法，提高总体反应率和每位患者的原发性抗肿瘤反应深度，并无限期延长BRAF突变黑色素瘤患者的缓解时间。为了实现这些目标，本项目的短期目标是利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途径靶向抑制剂来阐明BRAFV600E/PI3'-激酶途径在黑色素瘤形成中的分子机制，以及在临床前环境中联合途径靶向阻断的后果。在Aim 1中，GEM模型将用于探讨PI3'- kinase->AKT信号在与致癌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Aim 2中，将使用BRAFV600E引发的黑色素瘤GEM模型来评估联合抑制BRAFV600E或PI3’-激酶与单一药物抑制在促进肿瘤消退方面的优势。为了补充Aim 2中小鼠黑色素瘤标本的分析，Aim 3将使用一组真正表达BRAFV600E的人黑色素瘤细胞系来阐明BRAFV600E与PI3'-kinase->AKT信号通过影响蛋白质合成来调节黑色素瘤细胞分裂周期和/或凋亡的分子机制。一旦完成，这些研究将为开发稳健、合理、靶向通路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质量和数量。

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.