Microenvironmental FGF2-mediated resistance to anti-estrogen and PI3K/mTOR pathway therapeutics in ER+ breast cancer

项目摘要 尽管抗雌激素疗法在治疗雌激素受体患者方面取得了临床上的成功- 阳性(ER)乳腺癌，~1/3的患者在辅助治疗中复发，几乎 所有患者均在转移环境中接受治疗。磷脂酰肌醇3-激酶(PI3K)/机制靶点 雷帕霉素(MTOR)途径与抗雌激素耐药有关，针对这些的药物 这些途径已获批准或正在进行临床试验。不幸的是，几乎所有的ER乳腺癌都是在这些基础上进展的 治疗也是如此。患者疾病复发率高，尽管在#年治疗效果显著 临床前模型，使我们假设肿瘤微环境的组成部分对 ER乳腺癌患者对抗雌激素药物和PI3K/mTOR抑制剂的耐药性。用一本小说， 结合高通量筛查和生物信息学的微环境方法，我们发现 成纤维细胞生长因子2(FGF2)作为抗雌激素和PI3K/mTOR耐药的有效介质 在与ER乳腺癌微环境相关的正常组织中高表达的抑制物。 FGF2将细胞从治疗诱导的凋亡和细胞周期停滞中拯救出来，而拯救被一种 针对所有四种成纤维细胞生长因子受体(FGFRs)的FGF2特异性抗体或激酶抑制剂。我们假设 FGF2单独和联合介导对抗雌激素和PI3K/mTOR抑制剂的耐药性， 通过FGFR下游的路径汇聚在调节细胞命运的信号节点上，并且 在原发和转移性ER的情况下，FGF2靶向治疗可以消除耐药性 乳腺癌。特异靶1将确定成纤维细胞生长因子2介导的抗逆转录病毒营救的确切机制(S) 雌激素和PI3K/mTOR抑制剂，可能提供必要的新的肿瘤特异性治疗靶点 对于抗性表型。将使用遗传方法确定FGFR异构体的特异性，以及 FGF2介导的抗性所涉及的下游信号网络的鉴定将使用 免疫印迹和磷蛋白质组学。特定目标2将使用3个与微环境相关的肿瘤模型 评估靶向FGF2是否增强对抗雌激素和PI3K的反应 抑制剂。FGF2在乳腺组织、骨和原代成纤维细胞中高度表达，因此我们将利用 这些肿瘤微环境的模型：1)原位原发乳腺癌患者来源的异种移植 (PDX)模型，2)申请人开发的骨转移细胞系来源的异种移植模型，以及3)a 大量招募宿主来源的FGF2分泌成纤维细胞的小鼠ER乳腺癌模型。 通过这些研究，我们将发现FGF2所需的潜在可药物蛋白质靶点- 介导耐药，为FGF2导向治疗ER乳腺确定合适的临床环境 癌症。这些进展将改进治疗策略，以消除和预防抗药性。 雌激素和PI3K/mTOR对ER乳腺癌患者的指导治疗。

Project Summary Despite the clinical success of anti-estrogen therapies for the treatment of patients with estrogen receptor- positive (ER+) breast cancer, recurrences occur in ~1/3 of patients treated in the adjuvant setting and almost all patients treated in the metastatic setting. The phosphatidylinositol 3-kinase (PI3K)/mechanistic target of rapamycin (mTOR) pathway has been implicated in anti-estrogen resistance, and drugs targeting these pathways are approved or in clinical trials. Unfortunately, nearly all ER+ breast cancers progress on these therapies as well. The high prevalence of disease recurrence in patients, despite dramatic treatment efficacy in preclinical models, led us to postulate that components of the tumor microenvironment significantly contribute to resistance to anti-estrogens and PI3K/mTOR inhibitors in ER+ breast cancer. Using a novel, microenvironment-focused approach combining high-throughput screening and bioinformatics, we uncovered fibroblast growth factor 2 (FGF2) as a potent mediator of resistance to both anti-estrogens and PI3K/mTOR inhibitors that is highly expressed in normal tissues relevant to the microenvironments of ER+ breast cancer. FGF2 rescues cells from treatment-induced apoptosis and cell cycle arrest, and rescue is abrogated by an FGF2-specific antibody or a kinase inhibitor targeting all four FGF receptors (FGFRs). We hypothesize that FGF2 mediates resistance to both anti-estrogens and PI3K/mTOR inhibitors, alone and in combination, through pathways downstream of FGFRs that converge on signaling nodes that modulate cell fate, and that resistance can be abrogated with FGF2-targeted therapeutics in settings of both primary and metastatic ER+ breast cancer. Specific Aim 1 will determine the precise mechanism(s) of FGF2-mediated rescue from anti- estrogens and PI3K/mTOR inhibitors, which may provide novel tumor-specific therapeutic targets necessary for the resistance phenotype. FGFR isoform specificity will be determined using genetic approaches, and identification of downstream signaling networks involved in FGF2-mediated resistance will be achieved using immunoblotting and phosphoproteomics. Specific Aim 2 will use 3 microenvironmentally-relevant tumor models of ER+ breast cancer to assess whether targeting FGF2 enhances response to anti-estrogens and PI3K inhibitors. FGF2 is highly expressed in mammary tissue, bone, and primary fibroblasts, so we will utilize models of these tumor microenvironments: 1) an orthotopic primary breast cancer patient-derived xenograft (PDX) model, 2) a bone metastasis cell line-derived xenograft model developed by the applicant, and 3) a murine ER+ mammary adenocarcinoma model that heavily recruits host-derived FGF2-secreting fibroblasts. Through these studies, we will uncover potentially druggable protein targets that are required for FGF2- mediated drug resistance, and define the appropriate clinical setting for FGF2-directed therapy for ER+ breast cancer. These advances will improve therapeutic strategies to abrogate and prevent resistance to anti- estrogens and PI3K/mTOR-directed therapies in patients with ER+ breast cancer.