Investigation of CXCR7 signaling in EGFR TKI resistant NSCLC

尽管EGFR靶向治疗显著延长了伴有EGFR的非小细胞肺癌患者的生存时间 激活域突变，获得性对EGFR酪氨酸激酶抑制剂(TKIs)的耐药性 构成了一个重大的临床问题。最近的临床研究表明，越来越多的人 这些耐药的NSCLC中有许多经历了上皮向间充质转化(EMT)；然而， 具有EMT表型的获得性EGFR TKI的分子基础仍然难以捉摸。因此， 获得性耐药患者不能从有效的治疗中受益。我们有 结果表明，抑制突变型表皮生长因子受体可促进转化生长因子β1介导的细胞内皮细胞转化。在……里面 患者标本中，C-X-C趋化因子受体7型(CXCR7)在 具有EMT表型的获得性EGFR TKI抗性NSCLC细胞。长期耗尽 在耐药细胞中携带shRNA的CXCR7不仅恢复了上皮表型，而且还恢复了敏感性 至EGFR TKI。我们的中心假设是CXCR7是一个新的治疗靶点 促进EGFR突变型NSCLC的EMT表型并提供交替的存活/增殖 突变时的通路--EGFR被抑制。总体目标是确定机制 CXCR7通过什么促进EMT，从而对EGFR TKI产生抵抗，并决定CXCR7是否 是治疗非小细胞肺癌的优良药物靶点。在目标1中，我们将确定 CXCR7促进EGFR TKI耐药非小细胞肺癌的存活。为此，我们将调查是否有 CXCR7的配体激活是抗病表型结合所必需的。另外， 我们将使用体外和体内模型评估抑制CXCR7的治疗方法 针对具有EGFR-TKI抗性的EMT相关NSCLC细胞的信号转导。在目标2中， 我们将确定CXCR7在非小细胞肺癌中调控EMT的机制。为此， 我们将研究CXCR7是如何激活下游转录因子来支持EMT的 EGFR突变型NSCLC通过基因组学和蛋白质学方法，细胞培养和 互补转基因小鼠EGFR突变型非小细胞肺癌模型。在目标3中，我们将确定 EMT靶向CXCR7消除EGFR TKI耐药细胞的疗效为了这个 目的：我们将研究具有EMT表型的EGFR TKI耐药细胞是否通过 利用PDX模型和免疫组化技术从CXCR7表达增加的耐药细胞进化而来 CXCR7抑制剂。从这一建议中获得的结果将有助于发现预后 以及抑制CXCR7表达导致EGFR TKI耐药的治疗工具，以防止 EMT诱导EGFR抑制，并为对符合以下条件的非小细胞肺癌患者进行分层提供理论依据 使用CXCR7靶向治疗的间质生物标记物对EGFR TKI产生耐受性。

Although EGFR-targeted therapy significantly prolongs the survival of NSCLC patients with EGFR kinase domain activating mutations, acquired resistance to EGFR tyrosine kinase inhibitors (TKIs) poses a significant clinical problem. Recent clinical studies demonstrated that an increasing number of these resistant NSCLCs undergo epithelial to mesenchymal transition (EMT); however, the molecular basis of acquired EGFR TKI with an EMT phenotype remains elusive. Consequently, patients with the acquired resistance do not benefit from effective therapies. We have demonstrated that the inhibition of mutant EGFR in NSCLC promotes TGFβ1-mediated EMT. In patient specimens, C-X-C chemokine receptor type 7 (CXCR7) is significantly upregulated in acquired EGFR TKI resistant NSCLC cells with an EMT phenotype. Prolonged depletion of CXCR7 with shRNA in the resistant cells not only restores epithelial phenotype but also sensitivity to EGFR TKIs. Our central hypothesis is that CXCR7 is a novel therapeutic target which promotes an EMT phenotype in EGFRmutant NSCLC and provides alternate survival/proliferation pathways when mutated-EGFR is inhibited. The overall objective is to determine the mechanism by which CXCR7 promotes EMT and thus resistance to EGFR TKI and determine whether CXCR7 is a superior drug target for NSCLC therapy. In Aim 1, we will determine the mechanism by which CXCR7 promotes survival of EGFR TKI resistant NSCLC. For this aim, we will investigate if a ligand activation of CXCR7 is required for the engagement of the resistant phenotype. Additionally, we will evaluate therapeutic approaches using in vitro and in vivo models to suppress CXCR7 signaling to specifically target EMT-associated NSCLC cells with EGFR-TKI resistance. In Aim 2, we will determine mechanisms responsible for EMT regulation by CXCR7 in NSCLC. To this end, we will investigate how CXCR7 activates downstream transcription factors to support EMT in EGFR mutant NSCLC by using genomics and proteomics approaches, cell culture and complementary transgenic murine EGFR mutant NSCLC models. In Aim 3, we will determine the therapeutic efficacy of targeting CXCR7 to eliminate EGFR TKI resistant cells with EMT. For this aim, we will investigate if EGFR TKI resistant cells with an EMT phenotype emerge through evolution from drug tolerant cells with increase expression of CXCR7 using PDX models and CXCR7 inhibitors. The results obtained from this proposal will facilitate the discovery of prognostic and therapeutic tools to inhibit CXCR7 expression leading to EGFR TKI resistance, to prevent the induction of EMT upon EGFR inhibition, and to provide a rationale to stratify NSCLC patients who become refractory to EGFR TKI with mesenchymal biomarkers for CXCR7-targeted therapeutics.