Investigation of CXCR7 signaling in EGFR TKI resistant NSCLC

尽管EGFR靶向治疗显著延长了EGFR阳性NSCLC患者的生存期， 激酶结构域激活突变，EGFR酪氨酸激酶抑制剂（TKI）获得性耐药 造成了严重的临床问题。最近的临床研究表明， 许多这些抗性NSCLC经历上皮向间充质转化（EMT）;然而， 具有EMT表型的获得性EGFRTKI的分子基础仍然难以捉摸。因此，委员会认为， 具有获得性耐药性的患者不能从有效的治疗中获益。我们有 证实了在NSCLC中抑制突变型EGFR促进TGFβ1介导的EMT。在 患者标本中，C-X-C趋化因子受体7型（CXCR 7）在 具有EMT表型的获得性EGFR TKI耐药NSCLC细胞。长期消耗 CXCR 7与shRNA在耐药细胞中不仅恢复上皮表型，而且恢复敏感性 EGFR TKI。我们的中心假设是CXCR 7是一种新的治疗靶点， 促进EGFR突变型NSCLC中的EMT表型，并提供交替存活/增殖 当突变的EGFR被抑制时，总体目标是确定机制 CXCR 7通过其促进EMT并因此促进对EGFR TKI的抗性，并确定CXCR 7是否 是NSCLC治疗的一个上级药物靶点。在目标1中，我们将确定 CXCR 7促进EGFR TKI耐药NSCLC的生存。为此，我们将调查是否存在 CXCR 7的配体活化是抗性表型参与所必需的。此外，本发明还 我们将评估使用体外和体内模型来抑制CXCR 7的治疗方法 特异性靶向具有EGFR-TKI抗性的EMT相关NSCLC细胞的信号传导。在目标2中， 我们将确定NSCLC中CXCR 7调控EMT的机制。为此，委员会建议， 我们将研究CXCR 7如何激活下游转录因子，以支持EMT。 EGFR突变型NSCLC通过使用基因组学和蛋白质组学方法、细胞培养和 互补转基因鼠EGFR突变体NSCLC模型。在目标3中，我们将确定 靶向CXCR 7以用EMT消除EGFR TKI抗性细胞的治疗功效。为此 目的是，我们将研究是否EGFR TKI耐药细胞与EMT表型出现，通过 使用PDX模型从具有增加的CXCR 7表达的药物耐受细胞进化， CXCR 7抑制剂。从这一建议中获得的结果将有助于发现预后 以及抑制导致EGFR TKI抗性的CXCR 7表达的治疗工具， EGFR抑制后诱导EMT，并提供对以下NSCLC患者进行分层的依据： EGFR TKI与间充质生物标志物的CXCR 7靶向治疗变得难治。

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.