N-cadherin调控AR/NDRG1信号介导前列腺癌去势抵抗的分子机制研究

Endocrine therapy plays an important role in the treatment of prostate cancer(PCa) at present. However, the most advanced stage of disease becomes castration resistant prostate cancer (CRPC) which is presently incurable and accounts for most PCa mortality. The mechanism and conversion of CRPC to hormone dependent prostate cancer(ADPC) is the key of the project. Our previous research found that persistent silence of N-cadherin can recover expression of AR and NDRG1 protein in CRPC PC-3 cells, start the growth inhibition process, and transform the cell characteristics of CRPC to ADPC. We speculate that N-cadherin may regulate AR DNA methylation through phosphorylated c-jun protein, and inhibit AR/NDRG1 signaling pathway to develop CRPC. Consequently, there is a feedback loop of N-cadherin/NDRG1 in prostate cancer. With regulation of the key factor in the loop, AR physiological function may be recovered due to DNA demethylation. Through the biological effects of NDRG1, androgen insensitivity can be reversed in castration resistant prostate cancer. Throughout the implementation of the project, we will focus on studying the regulation and molecular mechanism of N-cadherin/NDRG1 loop in CRPC, and further explore the relationship of AR and NDRG1. Androgen antagonist flutamide will be used to verify the regulation effect of the feedback loop on the sensitivity of CRPC endocrine therapy. Our study can provide a new theoretical basis for CRPC development and treatment.

多数中晚期前列腺癌（PCa）在内分泌治疗过程中会发展为去势抵抗前列腺癌（CRPC），预后极差。寻找CRPC发生的可能机制，并如何将CRPC转化为激素依赖性前列腺癌（ADPC）是本项目的关键。我们前期工作发现CRPC细胞PC-3中持续沉默N-cadherin基因，能使表达缺失的AR及NDRG1蛋白恢复，启动细胞生长抑制进程，细胞特性由CRPC向ADPC转变。我们推测，PCa中N-cadherin可能通过c-jun调控AR基因甲基化水平，抑制AR/NDRG1信号轴发挥作用，从而促进CRPC的形成。调控该通路关键因子，可以恢复AR生理性功能，通过NDRG1发挥生物学作用，逆转前列腺癌去势抵抗。通过该项目的实施，申请者将深入研究N-cadherin/NDRG1环路在CRPC中调控作用及分子机制，应用雄激素拮抗剂氟他胺验证调控反馈环路对CRPC内分泌治疗敏感性的影响，为CRPC提供新的治疗方案。

中晚期前列腺癌（PCa）在内分泌治疗过程中会发展为去势抵抗前列腺癌（CRPC），是肿瘤特异性死亡的主要因素。寻找CRPC发生的可能机制，并如何将CRPC转化为激素依赖性前列腺癌（ADPC）是本项目的关键。我们研究发现，N-cadherin/c-Jun/NDRG1轴在PCa发展过程中所发挥着重要作用。N-cadherin在恶性PCa组织中高表达，并通过c-Jun表观遗传抑制AR/NDRG1信号通路，从而达到抑制PCa增殖的作用。c-Jun在NDRG1启动子的TREs序列上与AR和DNMT1形成复合物，既可以通过DNMT1促进DNA甲基化，又可竞争性地抑制AR在ARE序列上的转录活性。抑制N-cadherin的表达明显促进了PCa在体内及体外对恩杂鲁胺治疗的敏感性。我们进一步研究还发现了新的表观调控因子MLL5α，它可通过激活AR/NDRG1信号通路抑制PCa进展。MLL5α的作用机制是直接与AR结合，识别NDRG1和KLK3启动子序列中的AREs，通过H3K4me3激活它们的转录。此外，细胞功能实验及动物实验证实，MLL5α可抑制PCa细胞增殖，并增进PCa对恩杂鲁胺治疗的敏感性。组织学研究表明，MLL5α的表达与PCa的Gleason评分和无复发生存率呈负相关。通过这一机制，我们认为MLL5α可能是PCa进展的生物标志物，MLL5α的沉默可能是PCa恶性进展的重要原因。总结起来，我们在本项目研究中发现并证实了AR/NDRG1通路在PCa发展过程中的关键作用。N-cadherin和MLL5α的表观遗传作用可有效调控该通路，进一步干预肿瘤的发展以及其对去势治疗的敏感性。通过调节N-cadherin和MLL5α的表达来激活该通路，可为克服CRPC进展和逆转CRPC提供新的方案。