Elucidating mechanisms of therapy response in BRCA2 mutant prostate cancers

摘要 前列腺癌是男性最常见的非皮肤恶性肿瘤，预计将导致34,500人死亡 2022年，仅在美国。晚期抗去势前列腺癌的测序研究 (CRPC)已经发现致病性BRCA2突变的发生率很高(~13%)。这些发现使人们能够 聚(ADP-核糖)聚合酶的临床试验和随后的食品和药物管理局(FDA)批准 (PARP)抑制剂(PARPis)奥拉帕利布和鲁卡帕里布治疗携带致病性BRCA2的晚期CRPC患者 突变。尽管最初有反应，但对PARPis的治疗抵抗是常见的。然而，分子 BRCA2突变体CRPC对PARPI的适应尚不清楚，这是因为缺乏 生物学和临床上相关的模型。我们建议的研究利用了两个新的患者衍生模型 致病BRCA2突变体CRPC系统将阐明PARPI的生物学机制 治疗反应并帮助解决临床上尚未满足的关键需求，以预防或克服对PARPis的耐药性。 在这项建议中，我们将使用两种新的致病基因突变模型，包括40511 PARPI敏感和耐药的LTL-610PDX。基因集浓缩分析(GSEA)和 利用这些新模型对RNA测序数据进行过度表示分析(ORA)表明 细胞外基质(ECM)调控相关基因在短期和长期中的上调 PARPI疗法。尤其是细胞外基质相关基因SERPINE1，它编码蛋白纤溶酶原 激活物抑制物1(PAI-1)是奥拉帕利治疗72小时后最显著的相关基因。 GSEA前沿分析。由于PAI-1典型地防止ECM降解，我们随后使用了Masson的 三色染色评估耐PARPI的LTL-610PDX和发现显著增加的I型 胶原蛋白沉积与其PARPI敏感亲本系比较。因为已知基质改变会影响 癌细胞存活，我们假设PARP1等ECM基因在BRCA2中的诱导作用 突变的CRPC导致肿瘤间质增强，并使治疗耐药。两个具体目标是 研究这一假说：在目标1中，我们将阐明SERPINE1信号在 BRCA2突变体CRPC细胞外、外和体内ECM沉积。在目标2中，我们将研究其机制。 BRCA2突变体CRPC对PARPI转录激活SERPINE1的研究这些研究的结果 研究将使系统的方法能够调节ECM改变以响应BRCA2突变体中的PARPI CRPC。

ABSTRACT Prostate cancer is the most common non-skin malignancy in men and is projected to cause 34,500 deaths in 2022 in the United States alone. Sequencing studies of advanced lethal castrate resistant prostate cancer (CRPC) have identified a high incidence (~13%) of pathogenic BRCA2 mutations. These findings have enabled clinical trials and subsequent Food and Drug Administration (FDA) approval of the poly (ADP-ribose) polymerase (PARP) inhibitors (PARPis) olaparib and rucaparib in advanced CRPC patients harboring a pathogenic BRCA2 mutations. Despite initial responses, therapy resistance to PARPis is common. However, the molecular adaptations that occur in BRCA2 mutant CRPC in response to PARPi are poorly understood, due to a lack of biologically and clinically relevant models. Our proposed studies leveraging two new patient-derived model systems of pathogenic BRCA2 mutant CRPC will elucidate the biological mechanisms implicated in PARPi therapy response and help address a critical clinical unmet need to prevent or overcome resistance to PARPis. In this proposal, we will use two new models of pathogenic BRCA2 mutations in CRPC, including the 40511 cell line and matched PARPi-sensitive and resistant LTL-610 PDXs. Gene Set Enrichment Analysis (GSEA) and Over-Representation Analysis (ORA) of RNA-sequencing data utilizing these novel models point to significant upregulation in genes involved in Extracellular Matrix (ECM) modulation in response to both short and long term PARPi therapy. In particular, the ECM associated gene SERPINE1, which encodes for the protein Plasminogen Activator Inhibitor 1, (PAI-1) is the most significantly implicated gene after 72 hours of olaparib treatment via GSEA leading edge analysis. Since PAI-1 canonically prevents ECM degradation, we then used Masson’s Trichrome staining to evaluate the PARPi resistant LTL-610 PDX and found dramatically increased Type I Collagen deposition compared to its PARPi sensitive parental line. Since stromal alterations are known to affect cancer cell survival, we hypothesize that the induction of ECM genes like SERPINE1 by PARPis in BRCA2 mutant CRPC results in enhanced tumor stroma, and enables therapy resistance. Two specific aims are proposed in this grant to study this hypothesis: in Aim 1, we will elucidate the role of SERPINE1 signaling in ECM deposition in BRCA2 mutant CRPC in vitro, ex vivo, and in vivo. In Aim 2, we will investigate the mechanism of transcriptional activation of SERPINE1 in BRCA2 mutant CRPC in response to PARPi. The results from these studies will enable systematic approaches to modulate ECM alterations in response to PARPi in BRCA2 mutant CRPCs.