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的惊人增加而闻名，特别是在年轻人中，侵袭性临床行为和致命转移的倾向，说明迫切需要针对这种疾病的新治疗策略。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中的关键驱动癌基因，如突变激活的BRAF。事实上，当BRAFV 600 E癌蛋白被维罗非尼抑制时，BRAF突变的黑色素瘤患者，即使是那些具有广泛传播的转移性疾病的患者，也享有显著的肿瘤消退以及显著的健康改善。然而，由于并非所有BRAF突变的黑色素瘤患者都对维罗非尼有反应，并且那些有反应的黑色素瘤患者通常会复发致命的耐药性疾病，因此黑色素瘤治疗的范例正朝着作用于BRAFV 600 E的通路靶向抑制剂和协同信号传导模块（如PI 3 '-激酶->AKT通路）的合理靶向组合发展。事实上，尽管vemurafenib的临床成功和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将BRAF抑制剂用于黑色素瘤治疗：最大化治疗益处; 2.最大限度地减少致命耐药疾病的出现; 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受体的联合疗法，以提高总体缓解率和每位患者的主要抗肿瘤反应的深度，并与UCSF黑素瘤诊所的同事合作，无限期延长BRAF突变黑素瘤患者的缓解期。为了实现这些目标，本提案的短期目标是采用最先进的基因工程小鼠（GEM）模型、真正的人黑素瘤细胞和一系列临床相关的通路靶向抑制剂，以阐明BRAFV 600 E/PI 3 '-激酶通路在黑素瘤发生中协同作用的分子机制以及在临床前环境中联合通路靶向阻断的后果。在目的1中，GEM模型将用于探测PI 3 '-激酶->AKT信号传导在与致癌BRAFV 600 E合作将正常黑素细胞转化为转移性黑色素瘤细胞中的重要性。在目的2中，将使用BRAFV 600 E引发的黑素瘤的GEM模型来评价BRAFV 600 E或PI 3 '-激酶的组合抑制相对于单一药剂抑制在促进肿瘤消退方面的优效性。为了补充目的2中的小鼠黑素瘤标本的分析，将在目的3中使用一组真正的表达人BRAFV 600 E的黑素瘤细胞系，以阐明BRAFV 600 E与PI 3 '-激酶->AKT信号传导通过对蛋白质合成的影响在调节黑素瘤细胞分裂周期和/或细胞凋亡中协同作用的分子机制。完成后，这些研究将为开发稳健合理的、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.