Study the Mechanism of Retinoblastoma Protein Mediated Androgen Receptor Transcriptional Repression Activity on DNA Replication

项目摘要 虽然AR已被广泛表征为转录激活剂，但最近报道， 作为转录抑制因子抑制基因的子集。值得注意的是，通过AR ChIP-seq和 在前列腺癌细胞中，我们发现直接AR抑制的基因高度表达， 这些基因中的大多数在CRPC临床中持续增加， 样品然后我们发现AR的这种直接转录抑制活性是由 雄激素刺激的低磷酸化Rb的募集。雄激素也被称为刺激生长， 进一步AR转录激活驱动脂质和固醇合成的基因，以及其他代谢功能， 随后细胞周期蛋白依赖性激酶活化和Rb过度磷酸化。AR的过度表达 前列腺癌细胞可以克服这种生长刺激作用。这些发现表明，AR具有 Rb依赖性抗增殖功能，其可能在Rb缺乏的CRPC细胞中受损， 可以通过阻断Rb磷酸化来增强。本提案的目的是确定 Rb的AR募集在调节DNA复制基因转录和细胞周期进程中的作用 PCa肿瘤细胞（特定目的1），以确定AR与低磷酸化 Rb和表征由AR募集到抑制位点的不同Rb复合物（特异性目的2），以及 进行全基因组分析以鉴定Rb依赖性AR抑制位点并确定其机制 这些位点在前列腺癌细胞中的作用和功能作用（具体目标3）。

Project Summary While AR has been extensively characterized as a transcriptional activator, it was recently reported to function as a transcriptional repressor to suppress a subset of genes. Significantly, through AR ChIP-seq and transcriptome profiling in prostate cancer cells we have found that the directly AR-repressed genes are highly enriched for DNA replication function and majority of those genes were consistently increased in CRPC clinical samples. We then discovered that this direct transcriptional repression activity of AR was mediated by androgen-stimulated recruitment of hypophosphorylated Rb. Androgens is also known to stimulate growth by further AR transcriptional activation of genes driving lipid and sterol synthesis, and other metabolic functions, with subsequent cyclin dependent kinase activation and Rb hyperphosphorylation. Overexpression of AR in prostate cancer cells could overcome this growth stimulatory effect. These findings demonstrate that AR has an Rb-dependent anti-proliferative function, which may be compromised in CRPC cells with Rb-deficiency and could be enhanced by blocking Rb phosphorylation. The objective of this proposal is to determine the function roles of AR recruitment of Rb in regulating transcription of DNA replication genes and cell cycle progression of PCa tumor cells (specific aim 1), to determine the molecular basis for AR interaction with hypophosphorylated Rb and characterize the distinct Rb complex recruited by AR to the suppression sits (specific aim 2), and to conduct a genome wide analysis to identify Rb dependent AR suppression sites and determine the mechanism of actions and function roles of these sites in prostate cancer cells (specific aim 3).