雄激素受体剪切变异体在前列腺癌中介导雄激素调节基因转录重编程机制的研究

Androgen receptor (AR) plays important roles in prostate cancer progression. The spliced variant forms of AR (AR-Vs) are truncated isoforms and have constitutive activity without androgen. Therefore, AR-Vs may be one of the important mechanisms for androgen deprivation therapy resistance and castration-resistant prostate cancer (CRPC) progression. But it is not clear that if AR-Vs could affect the modulation of androgen-regulated genes. In previous work, we found that AR-Vs could cause re-distribution of the genome-wide AR DNA binding sites. Combining roles of FOXA1 and epigenetic modifications in AR DNA binding, we hypothesize that AR-Vs could mediate transcriptional reprogramming of androgen-regulated genes in prostate cancer. We plan to perform Chromatin immunoprecipitation followed by DNA–sequencing (ChIP-seq) analysis to identify changes of genome-wide AR binding sites after knocking down AR-Vs. Their FOXA1 binding and epigenomic features can also be identified. Intergrated analysis with differential expression of androgen-regulated genes through RNA-seq, we could clarify the mechanism how AR-Vs mediate transcriptional reprogramming of androgen-regulated genes. This not only helps us understand roles of AR-Vs in CRPC progression, but also screen new tumor markers and theraputic targets for CRPC.

雄激素受体（AR）在前列腺癌进展中起重要作用。雄激素受体剪切变异体（AR-Vs）是全长AR截短的亚型，不需雄激素激活即具有转录活性，可能是雄激素剥夺治疗抵抗和去势抵抗性前列腺癌（CRPC）进展的重要机制之一。但关于AR-Vs对于前列腺癌雄激素调节基因转录的影响尚不清楚。在前期工作中，我们发现AR-Vs可能引起前列腺癌细胞中AR全基因组结合位点的重新分布，结合FOXA1和表观遗传学修饰在AR与DNA结合中所起的作用，我们提出假说认为AR-Vs能够介导雄激素调节基因转录的重编程。本项目拟采用ChIP-seq技术，鉴别AR-Vs敲低后全基因组结合位点的变化及其FOXA1结合情况和表观基因组学特征，结合RNA-seq所获得的差异性表达的雄激素调节基因，阐明AR-Vs介导雄激素调节基因转录重编程的机制。这不仅有助于理解AR-Vs在CRPC进展中的作用，而且有助于筛选CRPC新的肿瘤标志物及治疗靶点。

雄激素受体剪切变异体（AR-Vs）在去势抵抗性前列腺癌（CRPC）的进展中具有重要作用。AR-Vs表达的上调常常与雄激素剥夺治疗（ADT）后持续性的AR活性相关。但是，关于AR-Vs如何调节前列腺癌中雄激素调节基因的转录尚不清楚。在本项目中，我们采用ChIP-seq和RNA-seq技术，在CRPC细胞中，对ARV优势结合位点（ARV-PBS）以及它所调节激活的基因进行了鉴别。我们发现，AR-Vs优势结合在具有全长AR反应元件（AREfull）的、不含核小体的DNA区域，而全长AR优势结合位点（ARFL-PBS）位于含有FOXA1-nnnn-AREhalf的闭合染色体区域。进一步与肿瘤组织标本结合分析发现，ARV-PBS与去势抵抗性肿瘤患者的AR结合位点有广泛的重合，AR-Vs所调节激活的基因也在阿比特龙抵抗性患者标本中表达上调。其中，AR-Vs的靶基因包括癌基因RAP2A和细胞周期基因E2F7，这二者均与前列腺癌的去势抵抗、生存差以及肿瘤进展相关。通过本项目的研究，我们揭示了AR-Vs全基因组学结合位点的基因组学特征和表观遗传学特征，基本阐明了AR-Vs介导雄激素调节基因转录的机制，我们的数据还表明，AR-Vs优势调节的转录组基因可能成为有效治疗CRPC的靶点。