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

描述(由申请人提供)：黑色素瘤以其发病率惊人的增加而闻名，特别是在年轻、侵略性的临床行为和致命转移的倾向中，说明迫切需要针对这种疾病的新的治疗策略。尽管临床和流行病学情况黯淡，但基因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，当用维莫拉非尼从药物上抑制BRAFV600E癌蛋白时，BRAF突变的黑色素瘤患者，即使是那些患有广泛传播的转移性疾病的患者，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维莫拉非尼有反应，而且那些对致命性耐药疾病有反应的患者通常会复发，黑色素瘤治疗的范例正在朝着针对BRAFV600E的通路靶向抑制剂和协同信号模块(如PI3‘-激酶-AKT；AKT通路)的合理靶向组合发展。事实上，尽管维莫拉非尼在临床上取得了成功，我们对黑色素瘤细胞内部工作原理的科学了解也在不断增加，但挑战仍然是如何最好地使用BRAF抑制剂治疗黑色素瘤：1.最大限度地提高治疗效益；2.最大限度地减少致命耐药疾病的出现；以及3.减少潜在的有害副作用。因此，这项研究的长期总体目标是设计基于BRAF抑制剂的联合疗法，与加州大学旧金山分校黑色素瘤诊所的同事合作，提高每个患者的总体应答率和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时间。为了达到这些目标，这项建议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通路靶向抑制剂来阐明BRAFV600E/PI3‘-K通路协同作用在黑色素瘤发生中的分子机制(S)，以及在临床前环境下联合通路靶向阻断的后果。在目标1中，将使用GEM模型来探讨PI3‘-激酶-&GT；AKT信号在与致癌基因BRAFV600E协同将正常黑素细胞转化为转移性黑色素瘤细胞过程中的重要性。在目标2中，将使用BRAFV600E引发的黑色素瘤的GEM模型来评估联合抑制BRAFV600E或PI3‘-激酶促进肿瘤消退的优势。为了补充对AIM 2中的小鼠黑色素瘤标本的分析，在AIM 3中将使用一组真正表达黑色素瘤细胞系的人BRAFV600E来阐明BRAFV600E与PI3‘-K-GT；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/或细胞凋亡的分子机制(S)。完成后，这些研究将为开发强大而合理的、以通路为目标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.