FOXA1 regulates cytokine signaling and immune landscape in prostate cancer through ARID1A

摘要 前列腺癌是最常见的癌症，也是导致癌症死亡的第二大原因。 在美国男性身上。雄激素剥夺疗法和雄激素受体(AR)途径抑制剂延长 患者寿命延长，但往往会产生耐药性，导致耐去势前列腺癌(CRPC)。 免疫治疗，如免疫检查点抑制剂(ICI)，已经在一些癌症中显示出巨大的前景。 然而，CRPC对ICI的反应很差，主要是由于免疫抑制对肿瘤的侵袭。 细胞，如髓系抑制细胞和肿瘤相关巨噬细胞()。这个 这些细胞的聚集抑制了CD4+/CD8+T细胞的生长和活性，导致免疫抑制 肿瘤免疫微环境(时间)。MDSCs和TAM被炎性细胞因子吸引，这些细胞因子 由肿瘤细胞在肿瘤内在因素的调节下分泌。FOXA1是一种转录因子 是正常的前列腺发育和分化所必需的。然而，FOXA1在CRPC中下调， 在12-13%的转移性CRPC中发现FOXA1的体细胞点突变。我们之前已经 研究表明，FOXA1缺失或突变增加了上皮向间充质转化(EMT)，谱系可塑性， 通过诱导炎性细胞因子如TGFB3和IL8，促进细胞运动和PCa转移。然而，如何 FOXA1作为转录抑制因子以及FOXA1是否调节PCa的免疫格局 仍然不为人所知。在初步研究中，我们发现FOXA1抑制一组炎性细胞因子，如 已知的招募MDSCs和TAM的肿瘤坏死因子Į、CCL2、CCL20、CXCL5、TGFB3和IL8。 从机制上，我们观察到FOXA1蛋白与SWI/SNF染色质的一个亚单位ARID1A相互作用 重塑复合体，已被证明起到转录抑制和抑制炎症的作用 卵巢癌中的细胞因子。至关重要的是，前列腺特异性共缺失转基因小鼠模型的分析 FOXA1和Pten的小鼠比Pten小鼠显示出更具侵袭性的肿瘤和大量的巨噬细胞浸润。 因此，我们假设1)FOXA1将ARID1A蛋白招募到染色质中进行表观遗传重塑和 转录抑制，2)FOXA1缺失或突变释放ARID1A，导致炎性细胞因子 诱导、免疫抑制时间和前列腺癌进展。为了检验这些假设，在目标1中，我们将 研究FOXA1和ARID1A蛋白在前列腺癌中的相互作用、共占染色质以及相互作用 对炎性细胞因子转录抑制的依赖性。我们还将确定这些 功能受到与PCA相关的FOXA1突变的干扰。目标2将调查FOXA1枯竭是如何在 转基因小鼠影响前列腺癌进展、Arida1a功能、细胞因子诱导和肿瘤免疫 并进一步验证该途径在人CRPC组织中的渗透。

Summary Prostate cancer (PCa) is the most commonly diagnosed cancer and the second leading cause of cancer death in American males. Androgen deprivation therapies and androgen receptor (AR) pathway inhibitors extend patient lifespan, yet resistance often develops, leading to castration-resistant prostate cancer (CRPC). Immunotherapies, such as immune checkpoint inhibitors (ICI), have shown great promise in some cancers. However, CRPC has displayed a poor response to ICI, mainly due to tumor infiltration by immunosuppressive cells, such as myeloid-derived suppressor cells (MDSC) and tumor-associated macrophages (TAM). The accumulation of these cells inhibits CD4+/CD8+ T cell growth and activity, leading to an immunosuppressive tumor-immune microenvironment (TIME). MDSCs and TAMs are attracted by inflammatory cytokines that are secreted by the tumor cells under the regulation of tumor-intrinsic factors. FOXA1 is a transcription factor that is required for normal prostate development and differentiation. However, FOXA1 is down-regulated in CRPC, and somatic point mutations of FOXA1 were found in about 12-13% of metastatic CRPC. We have previously shown that FOXA1 loss or mutations increase epithelial-to-mesenchymal transition (EMT), lineage plasticity, cell motility, and PCa metastasis by inducing inflammatory cytokines such as TGFB3 and IL8. However, how FOXA1 acts as a transcriptional repressor and whether FOXA1 regulates the immune landscape of PCa remain unknown. In preliminary studies, we found that FOXA1 inhibits a panel of inflammatory cytokines, such as TNFĮ, CCL2, CCL20, CXCL5, TGFB3, and IL8 that are known to recruit MDSCs and TAMs. Mechanistically, we observed that FOXA1 protein interacts with ARID1A, a subunit of the SWI/SNF chromatin remodeling complex that has been shown to act as a transcriptional repressor and inhibit inflammatory cytokines in ovarian cancer. Critically, analyses of a transgenic mouse model with prostate-specific co-deletion of Foxa1 and Pten showed a more aggressive tumor with massive macrophage infiltration than the Pten mice. We thus hypothesize that 1) FOXA1 recruits ARID1A protein to the chromatin for epigenetic remodeling and transcriptional repression, 2) FOXA1 loss or mutation unleashes ARID1A, leading to inflammatory cytokine induction, an immunosuppressive TIME, and PCa progression. To test these hypotheses, in Aim 1, we will investigate FOXA1 and ARID1A protein interaction in PCa, co-occupancy on the chromatin, and mutual dependency for transcriptional repression of inflammatory cytokines. We will also determine how these functions are disrupted by PCa-associated FOXA1 mutations. Aim 2 will investigate how Foxa1 depletion in the transgenic mice affects PCa progression, Arida1a function, cytokine induction, and tumor immune infiltration and further validate the pathway in human CRPC tissues.