microRNA-200b低表达增强前列腺癌雄激素非依赖性的分子机制研究

Androgen-independent prostate cancer (AIPC) is a refractory prostate cancer with a poor prognosis. However, the underlying mechanism is still unclear. It is known that microRNAs play important role in regulating the process of tumor genesis. Based on our former studies, when compared with androgen-dependent prostate tumor, expression of miR-200b in AIPC cells and tissues were significantly reduced. Overexpression of miR-200b can significantly inhibit the proliferation of AIPC cells. At the same time, results from both proteomic and bioinformatics analysis have shown that Notch1 and PRDX2 may be potential target genes of miR-200b in the process of AIPC genesis and development. Furthermore, proteins encoded by NOTCH1 or PRDX2 were found to participate in regulation of Akt-NF-kB signal pathway. Accordingly, we hypothesized: when androgen is removed, expression of miR-200b will decrease and then leads to elevation in gene activity of NOTCH1 and PRDX2. This will enhance activity of Akt-NF-kB signaling, which may further promote cell proliferation and invasiveness. This project plans to confirm this hypothesis at molecular level and to demonstrate it from cell biological characteristics and clinical relevance.

雄激素非依赖性前列腺癌（AIPC）是难治性前列腺癌，其发生机制并不清楚。近年研究发现microRNAs在肿瘤发生发展过程中发挥重要调控作用。本课题组前期研究证实：相对于雄激素依赖性前列腺癌，AIPC组织和细胞中miR-200b表达显著下调，过表达miR-200b能够显著抑制AIPC细胞增殖。蛋白质组学技术结合生物信息学分析结果提示：NOTCH1和PRDX2可能是AIPC发生过程中miR-200b的靶基因，而NOTCH1和PRDX2编码蛋白均参与Akt-NF-kB通路的调节。因此，我们提出以下假说：前列腺癌细胞受到雄激素撤除打击后，部分细胞miR-200b表达下调，从而使本受其抑制的靶基因NOTCH1/PDRX2表达上调，进而增强NF-kB活性，促进细胞增殖、侵袭力增强，细胞转变为AIPC，这可能是AIPC发生机制之一。本项目将从分子水平、细胞生物学特性和临床相关性三个方面对此假说进行验证。

雄激素非依赖性前列腺癌（AIPC）是难治性前列腺癌，其发生机制并不清楚。近年研究发现microRNAs在肿瘤发生发展过程中发挥重要调控作用。本课题组前期研究证实：相对于雄激素依赖性前列腺癌，AIPC 组织和细胞中miR-200b 表达显著下调，过表达miR-200b能够显著抑制AIPC 细胞增殖。蛋白质组学技术结合生物信息学分析结果提示：NOTCH1 和PRDX2 可能是AIPC 发生过程中miR-200b 的靶基因，而NOTCH1 和PRDX2 编码蛋白均参与Akt-NF-kB 通路的调节。因此，我们提出以下假说：前列腺癌细胞受到雄激素撤除打击后，部分细胞miR-200b 表达下调，从而使本受其抑制的靶基因NOTCH1/PDRX2 表达上调，进而增强NF-kB 活性，促进细胞增殖、侵袭力增强，细胞转变为AIPC，这可能是AIPC 发生机制之一。本项目证明了miR-200b对NOTCH1、PRDX2表达的调控作用，阐明NOTCH1和PRDX2对AIPC细胞表型的影响。本项目还对重要信号通路Akt通路的机制进行了探讨，表明在前列腺癌细胞中，Akt通路激活，能够增强RB磷酸化，磷酸化的RB释放出转录因子E2F，随后E2F与基因结合激活转录，从而促进前列腺癌增殖。由于miRNAs多靶点的作用，本研究还改进了无雄激素培养环境下PC-3细胞靶基因的筛选策略：过表达和抑制miR-200b表达，用label free的蛋白质组学方法比较与对照细胞的蛋白质表达谱，获得可能的靶基因7个，结合生物信息学分析缩小范围至靶基因5个。本项目为进一步研究前列腺癌细胞雄激素非依赖性机制提供了有价值的方向，揭示其中的规律，将为雄激素非依赖性前列腺癌的治疗提供更多的治疗选择。