REGULATION AND ADAPTIVE MECHANISMS OF ONCOGENIC RAS/ERK SIGNALING

项目摘要/摘要 超过40%的人类癌症是由过度激活的RTK/RAS/RAF/MEK/ERK信号(MAPK)驱动的 路径)。使用小分子RAF或MEK抑制剂靶向MAPK信号转导是一种有效的治疗方法 策略，但这些药物的抗肿瘤活性通常被不同的机制减弱 适应性抵抗。一种这样的常见机制是缓解负面反馈的结果，这促进了 多受体酪氨酸激酶(RTK)的表达和活性上调，进而激活 RAS和下游MAPK信号通路中存在抑制剂。此外，与MAPK如何- 定向治疗可以通过最小限度地影响正常组织来实现更高的治疗指数，以及如何 它们与免疫检查点疗法的最佳结合在很大程度上仍未解决。Shp2(PTPN11)是一种 介导多个RTK下游信号转导的非受体蛋白酪氨酸磷酸酶 与Grb2和其他接头蛋白结合形成促进RAS激活的复合体。Shp2有 也被认为具有免疫抑制作用，但SHP2的这一功能也相对 未得到充分研究。靶向高效、选择性变构小分子抑制剂的研究进展 Shp2通过共同靶向两种致癌基因提供了潜在克服适应性耐药的机会 信号和反馈诱导的RTK介导的RAS激活依赖于MAPK失控 发信号。使用这样的SHP2抑制剂SHP099，我们发现SHP2和MAPK的组合靶向 在MAPK依赖肿瘤的特定亚群中，信号可阻止适应性耐药。在每个由MAPK驱动的 肿瘤分析，诱导p(Y542)SHP2，SHP2激活的替代标记物，以响应MAPK 联合治疗的敏感性需要抑制。该策略在肿瘤模型中广泛有效。 代表目前没有靶向治疗选择的侵袭性癌症类型， 包括三阴性乳腺癌(TNBC)模型，以及在G12具有RAS突变的肿瘤。在……里面 相反，RAS(G13D)/(Q61X)突变与肿瘤对该组合的耐药性有关，揭示了 迄今为止未被认识到的突变-RAS信号的复杂性和不同RAS依赖的可变性 RTK/SHP2上游信号的突变体。最后，使用体外共培养肿瘤细胞/T细胞系统 发现SHP2抑制可增强T细胞功能。基于这些观察，我们现在计划使用特定的 抑制剂以及生化和细胞为基础的方法，以全面研究调节野生- RTK/SHP2信号下游的类型和突变的RAS活性。我们将进一步研究体外和体内 体内对SHP2和MAPK联合抑制反应的分子和肿瘤类型特异性决定因素， 可作为潜在的生物标志物，以及这些疗法对正常组织和 免疫系统。目标是利用从这些研究中获得的机械性知识来开发小说 治疗MAPK驱动的癌症的有效组合药理学策略。

Project Summary/Abstract Over 40% of human cancers are driven by hyperactivated RTK/RAS/RAF/MEK/ERK signaling (MAPK pathway). Targeting MAPK signaling using small-molecule RAF or MEK inhibitors is a validated therapeutic strategy in cancer, but the antitumor activity of these drugs is commonly attenuated by various mechanisms of adaptive resistance. One such common mechanism is the result of relief of negative feedback which promotes upregulation of expression and activity of multiple Receptor Tyrosine Kinases (RTKs), which in turn activate RAS and downstream MAPK signaling in the presence of inhibitor. Further, questions relating with how MAPK- directed therapies can achieve a higher therapeutic index by minimally affecting normal tissue and how can they be optimally combined with immune checkpoint therapies remain largely unresolved. SHP2 (PTPN11) is a non-receptor protein tyrosine phosphatase that mediates signal transduction downstream of multiple RTKs by associating with GRB2 and other adaptor proteins to form a complex that promotes RAS activation. SHP2 has also been suggested to have an immunosuppressive role, but this function of SHP2 has also been relatively understudied. The recent development of potent and selective allosteric small-molecule inhibitors targeting SHP2 provided the opportunity to potentially overcome adaptive resistance by co-targeting both oncogenic signaling and feedback-induced RTK-mediated RAS activation in tumors dependent on deregulated MAPK signaling. Using one such SHP2 inhibitor, SHP099, we found that combinatorial targeting of SHP2 and MAPK signaling prevented adaptive resistance in defined subsets of MAPK-dependent tumors. In each MAPK-driven tumor analyzed, induction of p(Y542)SHP2, a surrogate marker of SHP2 activation, in response to MAPK inhibition was required for combined treatment sensitivity. The strategy was broadly effective in tumor models representing aggressive cancer types for which there are no targeted therapeutic options currently available, including Triple Negative Breast Cancer (TNBC) models, as well as tumors with RAS mutations at G12. In contrast, RAS(G13D)/(Q61X) mutations were associated with tumor resistance to the combination, revealing a hitherto unappreciated complexity of mutant-RAS signaling and variability in the dependence of different RAS mutants on upstream RTK/SHP2 signaling. Finally, using an in vitro co-culture tumor cells/T cells system we found that SHP2 inhibition enhances T cell function. Based on these observations, we now plan to use specific inhibitors and biochemical and cell-based methods to comprehensively study mechanisms that regulate wild- type and mutant RAS activity downstream of RTK/SHP2 signaling. We will further investigate ex vivo and in vivo for molecular and tumor type-specific determinants of response to combined SHP2 and MAPK inhibition, that may be used as potential biomarkers and of the effects of these therapies on normal tissue and the immune system. The goal is to use the mechanistic knowledge gained by these studies to develop novel effective combinatorial pharmacologic strategies for MAPK-driven cancers.