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阳性患者方面取得了临床成功， 阳性（ER+）乳腺癌，复发发生在约1/3的患者治疗的辅助设置和几乎 所有在转移背景下接受治疗的患者。磷脂酰肌醇3-激酶（PI 3 K）/ 雷帕霉素（mTOR）途径与抗雌激素抗性有关，靶向这些途径的药物 已批准或正在进行临床试验。不幸的是，几乎所有的ER+乳腺癌都是在这些方面进展的。 治疗也是。尽管治疗效果显著，但患者的疾病复发率很高， 临床前模型，使我们假设肿瘤微环境的成分显着贡献 ER+乳腺癌对抗雌激素和PI 3 K/mTOR抑制剂的耐药性。利用小说， 结合高通量筛选和生物信息学的微环境为重点的方法，我们发现 成纤维细胞生长因子2（FGF 2）作为对抗雌激素和PI 3 K/mTOR的抗性的有效介质 在与ER+乳腺癌微环境相关的正常组织中高度表达的抑制剂。 FGF 2拯救细胞免于治疗诱导的凋亡和细胞周期停滞，并且拯救被一种抑制剂所消除。 FGF 2特异性抗体或靶向所有四种FGF受体（FGFR）的激酶抑制剂。我们假设 FGF 2介导对单独和组合的抗雌激素和PI 3 K/mTOR抑制剂的抗性， 通过聚集在调节细胞命运的信号节点上的FGFR下游途径， 在原发性和转移性ER+的情况下， 乳腺癌特异性目的1将确定FGF 2介导的从抗肿瘤中拯救的精确机制。 雌激素和PI 3 K/mTOR抑制剂，这可能提供必要的新的肿瘤特异性治疗靶点， 抗性表型。将使用遗传方法确定FGFR亚型特异性，并且 将使用以下方法鉴定参与FGF 2介导的抗性的下游信号网络： 免疫印迹和磷酸化蛋白质组学。Specific Aim 2将使用3种微环境相关肿瘤模型 评估靶向FGF 2是否增强对抗雌激素和PI 3 K的反应 抑制剂的FGF 2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）原位原发性乳腺癌患者来源的异种移植物 (PDX)模型，2）由申请人开发的骨转移细胞系衍生的异种移植物模型，和3）由申请人开发的骨转移细胞系衍生的异种移植物模型， 大量募集宿主来源的分泌FGF 2的成纤维细胞的鼠ER+乳腺癌模型。 通过这些研究，我们将发现潜在的可药物化的蛋白质靶点，这些蛋白质靶点是FGF 2- 介导的耐药性，并确定用于ER+乳腺癌的FGF 2导向治疗的适当临床环境 癌这些进展将改善治疗策略，以消除和预防抗- 雌激素和PI 3 K/mTOR导向疗法在ER+乳腺癌患者中的应用

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.