Abrogation of Therapeutic Escape Pathways in BRAF Mutant Melanoma

我们的长期目标是开发治疗策略，提高患者的生存率， 通过加强新的和现有的靶向治疗，治疗播散性黑色素瘤。尽管令人印象深刻的 在接受BRAF抑制剂治疗的BRAF突变型黑色素瘤患者中， 发生。已经描述了许多潜在的耐药机制，其中大多数绕过 突变型BRAF通过MAPK和PISK/AKT信号转导的再激活。尽管目前的临床策略 集中于BRAF抑制剂与MEK或PISK抑制剂联合使用， 可能导致黑色素瘤信号网络中许多节点处的多个细微信号改变， 甚至对这些组合的最终抵抗力。从概念上讲，我们认为自适应信号， 在大多数情况下，介导的耐药性都是“肿瘤内在的”，由肿瘤细胞的重新连接引起。 黑色素瘤信号转导网络，以及“宿主衍生”，由改变的生长因子介导 分泌和细胞外基质。我们的工作假设是， 只有当除了多个受体外，BF^F还可以靶向时，才能实现耐药性的消除。 酪氨酸激酶（RTK）和细胞/基质粘附信号。我们的初步研究表明， 到目前为止，参与逃避BRAF抑制剂治疗的信号蛋白是热的客户， 休克蛋白（HSP）-90，我们发现抑制HSP 90可以有效地预防和克服 在体外和体内的抗性。在这项提案中，我们将使用创新的磷酸化蛋白质组学和化学方法， 基于蛋白质组学的系统生物学方法来定义HSP“客户组”， 黑色素瘤对MAPK途径抑制（BRAF、MEK和BRAF+MEK）的获得性抗性。我们将 进一步研究成纤维细胞来源的信号在重塑黑色素瘤细胞的HSP-客户组中的作用 并将确定这如何使肿瘤逃避MAPK通路介导的凋亡。治疗前和治疗后 来自接受BRAF和HSP 90抑制剂组合的黑素瘤患者的活检 将分析（维罗非尼+XL 888）以寻找与以下相关的HSP客户蛋白降解模式： 长期治疗反应。总之，这些研究预计将提供一个系统水平的看法，如何 黑色素瘤细胞抵抗MAPK通路抑制，并将提供克服耐药性的新范例 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.