CDK5在MYCN驱动的前列腺癌神经内分泌转化中的作用和机制研究

The transcription factor MYCN is a key regulator of neuroendocrine differentiation (NED) in prostate cancer, and its specific mechanism for driving prostate cancer NED remains unclear. Studies have shown that CDK5 downstream of MYCN plays an important role in tumor NED. In our previous study, the bioinformatics analysis revealed that CDK5 regulatory subunits CDK5R1 and CDK5R2 were highly expressed in neuroendocrine prostate cancer (NEPC), and PARP1 may be involved in the regulation of CDK5. Therefore, the applicants hypothesized that CDK5 plays an important role in MYCN-driven prostate cancer NED, possibly through the "MYCN-PARP1-CDK5" pathway to induce the development of prostate cancer NED. This project uses immunohistochemistry，gene knockout/overexpression techniques, co-immunoprecitation experiment and inhibitors treatments to elucidate the role and mechanism of CDK5 in MYCN-driven prostate cancer NED at the human tissue，cellular and animal levels, to clarify the specific mechanism by which PARP1 is involved in the regulation of CDK5, and to provide a theoretical basis for the development of novel NEPC therapeutic drug via targeting CDK5.

转录因子MYCN作为前列腺癌神经内分泌转化（NED）的关键调控因子，其驱动前列腺癌NED的具体机制仍不明。研究表明MYCN下游的CDK5在肿瘤NED中发挥重要作用。申请人前期研究利用生物信息学分析发现CDK5的调节亚基CDK5R1、CDK5R2在神经内分泌前列腺癌（NEPC）中显著高表达，且PARP1可能参与CDK5的调控。因此，申请人提出假设：CDK5在MYCN驱动的前列腺癌NED中发挥重要作用，可能是通过“MYCN-PARP1-CDK5”通路诱导前列腺癌NED的发生。本项目将在人体组织标本、细胞和动物水平上，利用免疫组化技术、基因敲除、基因过表达技术、免疫共沉淀技术和抑制剂干预手段，阐明CDK5在MYCN驱动的前列腺癌NED中的作用和机制，明确PARP1参与调控CDK5的具体机制，为以CDK5为靶点开发全新的NEPC治疗药物提供理论依据。

神经内分泌前列腺癌（NEPC）预后极差，没有任何有效的治疗方法。研究前列腺癌神经内分泌分化（NED）的机制，寻找NEPC的治疗方法具有重要的临床意义。本课题从人体组织标本、细胞和动物水平上研究了 CDK5在MYCN驱动的前列腺癌NED中的作用和机制，证明了MYCN调控CDK5的表达依赖PARP1对DDR蛋白的多聚ADP-核糖化修饰作用。本研究进一步发现PARP抑制剂奥拉帕尼以及CKD5抑制剂Dinaciclib在小鼠模型中能够显著抑制NEPC的进展。阐述了CDK5通过CDK5R1和CDK5R2促进Rb1过度磷酸化，激活E2F1，进而促进NED基因（CHGA、NSE、SYP）的表达和NEPC增殖的机制。研究发现敲低MYCN抑制C4-2b、C4-2b-ENZR和NCI-H660细胞中CDK5R1、CDK5R2和E2F1的表达。CHIP-qPCR技术证实在前列腺癌细胞中N-Myc在CDK5R1、CDK5R2和E2F1基因启动子上富集。动物实验证实PARP抑制剂与CDK5抑制剂联合治疗NEPC可显著提高治疗效果。本研究在计划内容之外，通过公共数据库分析以及细胞实验证实，P2RX2在前列腺癌的进展中起到重要作用，其表达量的降低与更高的生化复发率及更差的临床病理参数相关，可作为预测病人预后的潜在标志物。本课题研究结果为临床上利用 PARP抑制剂及CDK5抑制干神经内分泌前列腺癌提供了理论依据。