USP39下调miR-185促进前列腺癌细胞恶性增殖的作用机制研究

Diet fat consuming is closely related to the tumorigenesis of prostate cancer. As the domestic daily life is improving in the past decade, the incidence of prostate cancer is rising greatly. Based on our clinical observation and preliminary results, we found that many of the PCa patients had hyperlipidemia, and showed an elevated expression of ubiquitin specific peptidase 39 (USP39), accompanied by an decrease of miR-185 tumor suppressor gene. We constructed lentivirus based vector expressing USP39-shRNA to transfect prostate cancer cells. The result showed that knockdown of USP39 significantly inhibited the excessive proliferation and colony formation of prostate cancer cells. Flowcytometry analysis indicated that knockdown of USP39 induced cell apoptosis and cell cycle arrest at G2/M in prostate cancer cells. Meanwhile, by PCR array we found that knockdown of USP39 could upregulate miR-185 expression. These results suggested that USP39 might be upregulated under hyperlipidemia condition and downregulate miR-185 expression to promote the malignant transformation of prostate cancer. To prove this hypothesis, this proposal aims to further study the molecular mechanism of how USP39 regulates miR-185 expression to promote tumorigenesis process of prostate cancer. The transgenic adenocarcinoma of the mouse prostate (TRAMP) model is proposed to further study the correlation of hyperlipidemia and the malignant transformation of prostate cancer. This study may uncover the molecular mechanism of prostate cancer formation and progression under the hyperlipidemia microenvironment, and provide markers for the prevention and treatment of prostate cancer.

组织微环境中脂类代谢异常与诸多恶性肿瘤密切相关。前期研究中我们发现：血脂水平与前列腺癌肿瘤分级正相关；高血脂组患者癌组织中USP39表达上调；高脂饮食可导致自发性前列腺癌小鼠癌组织中USP39表达上调。我们还发现：敲减USP39能促进前列腺癌细胞凋亡及抑制其增殖；敲减USP39后前列腺癌细胞中miR-185表达上调。我们已知miR-185能通过下调雄激素受体而抑制前列腺癌细胞的增殖、侵袭和迁移能力。本项目拟进一步筛选并验证脂类代谢异常微环境中调控USP39的信号分子；通过细胞实验阐明USP39调控miR-185的具体机制；通过动物实验明确高脂血症下USP39和miR-185的表达变化及与前列腺癌发病的相关性；系统分析血脂水平与前列腺癌发病及恶性程度的相关性。通过上述研究，初步阐明高脂血症下USP39下调miR-185促发前列腺癌的分子机制，为前列腺癌的预防和治疗提供新的分子靶标和理论依据。

前列腺癌是男性常见的癌症，高脂血症条件下的脂类代谢异常是前列腺癌发病的重要诱因。这表明组织微环境中脂类代谢异常与前列腺癌的发生发展密切相关。前期研究中我们发现：血脂水平与前列腺癌肿瘤分级正相关；高血脂组患者癌组织中USP39表达上调；高脂饮食可导致自发性前列腺癌小鼠癌组织中USP39表达上调。同时，敲减USP39能促进前列腺癌细胞凋亡及抑制其增殖；敲减USP39后前列腺癌细胞中miR-185表达上调，而miR-185能下调雄激素受体而抑制前列腺癌细胞的增殖、侵袭和迁移能力。因此USP39/miR-185有关的信号通路很可能是连接脂类代谢异常与前列腺癌发生发展之间的关键纽带。据此，本课题深入研究了“脂类代谢异常/USP39/miR-185”通路在前列腺癌的发生发展过程中扮演的角色。已有研究表明载脂蛋白APOE和APOJ分别与前列腺癌的患病风险有关，而尚无报道从载脂蛋白受体的角度深入研究。因此我们重点研究了两个重要的载脂蛋白受体LRP4和LRP11在前列腺癌中是否发挥作用。结果显示LRP4作为脂质代谢中的重要受体，可以通过调控USP39-miR185来影响前列腺癌的增殖，凋亡和侵袭性。而LRP11可以通过β-catenin通路来调控PD-L1的表达和功能，调控PD-L1介导免疫抑制，进而影响前列腺癌的发生发展。因此脂质代谢可以通过多个受体的途径来调控前列腺癌的发生发展。我们的研究进一步解释了高脂血症条件下的脂类代谢异常为什么会成为前列腺癌的高危因素，也为以后将脂类代谢作为前列腺癌的治疗靶点奠定了研究基础。