Understanding the role of an aberrant hepatic nuclear transcription circuit in prostate cancer tumorigenesis and castration resistance

项目摘要/摘要 前列腺癌中ERG融合的发现建立了一种范式，即非 在其他组织中处于生理水平的突变转录因子可以推动肿瘤的发生。我们有 发现前列腺癌的一个子集异常地表达通常仅限于 胃肠道(GI)，我们称之为PCA-GI特征。这种表型的流行率从 ~8%的原发前列腺癌到30%的耐去势转移性前列腺癌。我们的数据显示 这些GI基因受肝核因子1α和肝细胞核的协同调控 因子4γ(HNF4G)。这两个转录因子家族(HNF1和HNF4)以及任何FOXA家族 转录因子，已经被很好地描述为形成一个核心的自动调节环路来管理GI谱系 规范，并可以将成纤维细胞重新编程为GI谱系，类似于治理中的“山中因子” 胚胎干细胞谱系。前列腺系表达高水平的内源性FOXA1。 我们使用表达PCA-GI特征的22Rv1细胞株的初步数据表明 HNF1A/HNF4G转录回路是维持GI特异性基因表达和生长所必需的 HNF1A/HNF4G阳性的前列腺癌细胞。此外，HNF4G在HNF1A/HNF4G中的异位表达 阴性的前列腺癌细胞启动PCA-GI信号并导致更快的进展到 抗阉割。CHIP-SEQ研究表明，HNF4G是维持GI血统的必要和充分条件- 特异性增强子，暗示HNF4G是一种“先锋”转录因子，可以与封闭的染色质结合以 在前列腺谱系中建立新的增强剂。 我们建议的总体目标是了解异常表达的机制作用 HNF1A和HNF4G在前列腺癌发生和进展到去势抵抗中的作用。我们将利用 分子水平和临床效果良好的新一代前列腺癌患者来源器官模型 注释以定义肿瘤中异常激活HNF1A/HNF4G电路的广泛要求 PCA-GI签名。为了了解它们在肿瘤发生中的作用，我们将对异位HNF1A或HNF4G进行建模 不同基因工程小鼠前列腺组织类物质的表达 SPOPF133V突变、Chd1缺失和Pten缺失的组合。为了研究它们在抵抗阉割中的作用，我们 将在体外和体内模型中剖析它们与AR依赖的转录组的相互作用。我们将进一步 基因表达与细胞周期和染色质景观研究的相关性。如果成功，我们的研究将确定 前列腺癌发生和去势抵抗的新机制。HNF1A/HNF4G可以 被开发为生物标志物。此外，由于HNF4G是一种配体依赖的核转录因子， 前列腺癌的这一亚型有可能成为治疗的靶点。

PROJECT SUMMARY/ABSTRACT The discovery of ERG fusions in prostate cancer has set a paradigm where aberrant expression of non- mutated transcription factors at levels that are physiologic in other tissues can drive oncogenesis. We have uncovered that a subset of prostate cancers aberrantly express a gene signature normally restricted to the gastrointestinal (GI) tract and we call this the PCa-GI signature. The prevalence of this phenotype jumps from ~8% of primary prostate cancer to 30% of castration-resistance metastatic prostate cancer. Our data indicates that these GI genes are coordinately regulated by hepatic nuclear factor 1α (HNF1A) and hepatic nuclear factor 4γ (HNF4G). These two transcription factor families (HNF1 and HNF4), together with any FOXA-family transcription factor, have been well characterized to form a core autoregulatory loop to govern the GI lineage specification and can reprogram fibroblasts into the GI lineage, similar to the “Yamanaka factors” in governing the embryonic stem cell lineage. Prostate lineage express high endogenous levels of FOXA1. Our preliminary data using the 22Rv1 cell line that express the PCa-GI signature indicates that the HNF1A/HNF4G transcription circuit is required both to maintain expression of GI specific genes and for growth of HNF1A/HNF4G-positive prostate cancer cells. Further, ectopic expression of HNF4G in HNF1A/HNF4G- negative prostate cancer cells turns on the PCa-GI signature and leads to more rapid progression to castration-resistance. ChIP-seq studies show that HNF4G is necessary and sufficient to maintain GI lineage- specific enhancers, implying that HNF4G is a “pioneer” transcription factor that can bind to closed chromatin to establish novel enhancers in the prostate lineage. The overall objective of our proposal is to understand the mechanistic role of the aberrant expression of HNF1A and HNF4G in prostate cancer tumorigenesis and progression to castration resistance. We will utilize next-generation patient-derived prostate cancer organoid models that are molecularly and clinical well annotated to define the broad requirement of the HNF1A/HNF4G circuit in tumors that aberrantly activates the PCa-GI signature. To understand their role in tumorigenesis, we will model ectopic HNF1A or HNF4G expression in a mouse prostate organoids isolated from genetically engineered mice with different combinations of SPOPF133V mutation, Chd1 loss, and Pten loss. To study their role in castration-resistance, we will dissect their interaction with AR-dependent transcriptome in both in vitro and in vivo models. We will further correlate gene expression with cistrome and chromatin landscape studies. If successful, our studies will define a novel mechanism of prostate cancer tumorigenesis and castration resistance. HNF1A/HNF4G can be developed as biomarkers. Furthermore, because HNF4G is a ligand dependent nuclear transcription factor, this subset of prostate cancer can potentially be therapeutically targeted.