Targeting FOXA1-downstream pathways: a novel therapeutic strategy for castration-resistant prostate cancer

项目4：项目总结 前列腺癌(PC)是美国男性最常见的非皮肤癌。雄激素剥夺 针对雄激素受体(AR)的治疗(ADT)是转移性PC的主要治疗方法。新的- 一代抗雄激素药物苯扎鲁胺(ENZ)在延长患者生命方面几乎有效了整整一年。 然而，抗药性发展迅速。重要的是，抗去势PC(CRPC)主要是由异常驱动的 低雄激素环境下AR的激活。AR主要通过基因组发挥其致癌作用 靶基因表达的调控。这种基因组活动受到许多辅因子的严格调控，其中之一 这就是FOXA1。FOXA1传统上被认为是雄激素刺激的AR信号中的AR共激活剂。 然而，生物标记物研究报告了关于FOXA1是阳性还是阴性的有争议的结果 结果预测者，建议环境或治疗依赖的角色。此外，复发性、功能丧失 在PC中发现了FOXA1的突变，表明其具有肿瘤抑制作用。我们最近发现，虽然 FOXA1在局限性PC中相对于良性组织略有上调，在 CRPC。机制研究表明，FOXA1在AR信号的调节中具有双重作用。当着大家的面 在雄激素中，FOXA1增强AR信号并诱导细胞生长。然而，在没有雄激素的情况下， FOXA1抑制残留的AR活性，因此FOXA1缺失导致雄激素非依赖性AR激活 以及耐去势PC细胞的生长。此外，我们还发现FOXA1缺失也启动了转化生长因子/slug通路 促进细胞迁移和入侵。此外，在Enz耐药的CRPC中，转化生长因子/slug通路也被激活 细胞。因此，我们假设，针对转化生长因子/slug信号转导的临床可用的Alk5抑制剂可能会抑制 CRPC进展和克服联合治疗中的Enz耐药。为了检验这一假设，有三个 提出了具体的目标。在目标1中，我们将阐明FOXA1在抑制CRPC进展中的作用 在体外，最重要的是体内异种移植瘤。目标2将描述 FOXA1在CRPC细胞和PC标本中的表达。在目标3中，我们将研究Enz联合 Alk5抑制剂在CRPC细胞系和异种移植中的作用，而Aim 4将开发一项I期临床试验 Enz和Alk5抑制剂联合治疗转移性CRPC对于目标1和目标2，我们提出了初步的 数据，但在不抵抗去势的LNCaP细胞中；我们还没有在CRPC细胞系中测试我们的假设， 哪些与这项提议更相关。此外，目标1和目标1所述的拟议动物实验 AIM 2中的IHC染色涉及大量工作，尚未进行。此外，虚拟的 目标3和目标4中拟议的所有工作尚未完成。孢子资金对我们实现这一目标至关重要 项目。

PROJECT 4: PROJECT SUMMARY Prostate cancer (PC) is the most commonly diagnosed non-skin cancer in American men. Androgen deprivation therapies (ADT) that target the androgen receptor (AR) are the mainstay treatment for metastatic PC. New- generation anti-androgen enzalutamide (Enz) has been effective in prolonging patient life for almost a full year and yet resistance develops rapidly. Importantly, castration-resistant PC (CRPC) is driven primarily by aberrant activation of the AR in the milieu of low androgen. The AR exerts its tumorigenic roles mainly through genomic regulation of target gene expression. This genomic action is tightly regulated by a number of cofactors, one of which is FOXA1. FOXA1 is traditionally known as an AR co-activator in androgen-stimulated AR signaling. However, biomarker studies have reported controversial results regarding FOXA1 as a positive or negative outcome predictor, suggesting context- or treatment-dependent roles. In addition, recurrent, loss-of-function mutations of FOXA1 have been found in PC indicating tumor suppressive roles. We recently found that although FOXA1 is slightly up-regulated in localized PC relative to benign tissues, it is dramatically down-regulated in CRPC. Mechanistic studies revealed that FOXA1 has dual roles in its regulation of AR signaling. In the presence of androgen, FOXA1 enhances AR signaling and induces cell growth. However, in the absence of androgen, FOXA1 suppresses residual AR activity and as such FOXA1 loss leads to androgen-independent AR activation and castration-resistant PC cell growth. Moreover, we found that FOXA1 loss also turns on TGF /slug pathway contributing to cell migration and invasion. Further, TGF /slug pathway is also activated in Enz-resistant CRPC cells. We thus hypothesize that clinically-available ALK5 inhibitors that target TGF /slug signaling may suppress CRPC progression and overcome Enz-resistance in combinatorial therapies. To test this hypothesis, three specific aims are proposed. In Aim 1 we will elucidate the roles of FOXA1 in suppressing CRPC progression in vitro and most importantly in xenograft tumors in vivo. Aim 2 will characterize the downstream pathways of FOXA1 in CRPC cells and PC specimens. In Aim 3 we will investigate the efficacy of Enz in combination with ALK5 inhibitor in CRPC cell lines and xenografts, whereas Aim 4 will develop a phase I clinical trial of combinatorial Enz and ALK5 inhibitor treatment of metastatic CRPC. For Aims 1 and 2, we present preliminary data, but in LNCaP cells that are not castrate resistant; we have yet to test our hypothesis in CRPC cell lines, which are more relevant to this proposal. In addition, the proposed animal experiments described in Aim 1 and IHC staining in Aim 2 involve a substantial amount work and have not yet been performed. Furthermore, virtually all of the proposed work in Aims 3 and 4 is yet to be done. SPORE funding is critical for us to carry out this project.