Abrogation of Therapeutic Escape Pathways in BRAF Mutant Melanoma

我们的长期目标是开发治疗策略，以提高患者的存活率 通过加强新的和现有的靶向治疗来治疗播散性黑色素瘤。尽管有令人印象深刻的 BRAF抑制剂治疗突变型黑色素瘤患者的疗效：不可避免的耐药性 发生。已经描述了许多潜在的阻力机制，其中大部分绕过 突变的BRAF通过重新激活MAPK和Pisk/AKT信号。尽管目前的临床策略 都集中在BRAF抑制剂与MEK或PISK抑制剂的联合使用，开发 黑色素瘤信号网络中的许多节点上的多个、细微的信号变化可能导致 即使是对这些组合的最终抵抗。从概念上讲，我们认为自适应信号 在大多数情况下，中介耐药都是“肿瘤固有的”，是由于 黑色素瘤信号转导网络以及由改变的生长因子介导的“宿主来源” 基质成纤维细胞分泌和细胞外基质。我们的工作假设是，长期 只有当BF^F除了多个受体外还能被靶向时，才能消除耐药性 酪氨酸激酶(RTKs)和细胞/基质黏附信号。我们的初步研究表明，即使不是全部，也是大部分 到目前为止，在逃脱BRAF抑制剂治疗中涉及的信号蛋白中，有一部分是热的客户 休克蛋白(HSP)-90，我们发现抑制HSP90可以有效地预防和克服 在体外和体内都有耐药性。在这项提案中，我们将使用创新的磷蛋白质组-和化学 基于蛋白质组学的系统生物学方法定义热休克蛋白“客户组”，驱动内在和 黑色素瘤对MAPK通路抑制(BRAF、MEK和BRAF+MEK)的获得性耐药。我们会 进一步研究成纤维细胞来源的信号在黑色素瘤细胞热休克蛋白客户组重塑中的作用 并将确定这如何使肿瘤逃脱MAPK抑制剂介导的细胞凋亡。治疗前和治疗后 接受BRAF和HSP90抑制剂联合治疗的黑色素瘤患者的活检组织 (vemurafenib+XL888)将被分析，以寻找与以下相关的HSP客户蛋白质降解模式 长期治疗反应。总而言之，这些研究有望给出一个系统层面的观点，即如何 黑色素瘤细胞抵抗MAPK通路抑制，将为克服耐药性提供新的范例 死于黑色素瘤。

Our long-term goal is to develop therapeutic strategies that improve the survival of patients with disseminated melanoma by potentiating new and existing targeted therapies. Despite the impressive responses achieved in BRAF mutant melanoma patients treated with BRAF inhibitors, resistance inevitably occurs. A number of potential resistance mechanisms have been described, the majority of which bypass mutant BRAF through the reactivation of MAPK and PISK/AKT signaling. Although current clinical strategies are focused upon the use of BRAF inhibitors in conjunction with MEK or PISK inhibitors, the development of multiple, subtle signaling alterations at many nodes within the melanoma signaling network is likely to result in eventual resistance even to these combinations. Conceptually, we believe that the adaptive signals that mediate resistance in the majority of cases are both "tumor-intrinsic", resulting from the rewiring of the melanoma signal transduction network, as well as "host-derived", mediated by altered growth factor secretion and extracellular matrix from stromal fibroblasts. Our working hypothesis is that long-term abrogation of resistance will only be achieved if BF^F can be targeted in addition to multiple receptor tyrosine kinase (RTKs) and cell/matrix adhesion signals. Our preliminary studies suggest that most if not all of the signaling proteins implicated thus far in the escape from BRAF inhibitor therapy are clients of heat shock protein (HSP)-90, and we showed that inhibition of HSP90 was effective at preventing and overcoming resistance both in vitro and in vivo. In this proposal, we will use innovative phosphoproteomic- and chemical proteomic-based systems biology approaches to define the HSP "clientome" that drives intrinsic and acquired resistance of melanomas to MAPK pathway inhibition (BRAF, MEK and BRAF+MEK). We will further investigate the role of fibroblast-derived signals in remodeling the HSP-clientome of melanoma cells and will determine how this allows the tumor to escape MAPK inhibitor-mediated apoptosis. Pre- and post-treatment biopsies from melanoma patients receiving a BRAF and HSP90 inhibitor combination (vemurafenib+XL888) will be analyzed to look for patterns of HSP client protein degradation associated with long-term therapeutic response. Together, these studies are expected to give a systems level view of how melanoma cells resist MAPK pathway inhibition and will provide new paradigms to overcome drug resistance in melanoma.