USP39及其SUMO化修饰促进前列腺癌细胞增殖的作用机制研究

Prostate cancer is one of the threatens to man.Researches demonstrated that SUMO specific proteases expressed abnormally in Specimens of prostate cancer patients. In our previous work, we demonstrated that USP39 was one of the SUMO targets, and overexpression of USP39 and its SUMO sites mutant affected cell proliferation in prostate cancer cells,but the mechanisms are still unclear. Based on the previous work, we will collect samples from patients and test the expression of USP39, by combining shRNA with cell proliferation assay, we further wonder if there are relationship between USP39 and prostate cancer. By applying co-IP and shRNA techniques ,we want to know which SENP regulates the SUMOylation of USP39. By testing the functions and characteristics of USP39 before and after SUMO sites mutation, we want to study how SUMOylation regulates the activity of USP39 in prostate cancer. We will further demonstrate both USP39 and its SUMO sites mutant can promote prostate cancer development by animal experiments. The successful completion of this project may open perspectives for treating prostate cancer and provide a new anticancer target. We may know more on how SUMO regulates spliceosome by revealing the function change before and after SUMOylation of USP39. It has great scientific significance.

前列腺癌是一种严重威胁男性健康的疾病。研究表明,前列腺癌组织中SUMO特异性蛋白酶表达异常。本课题组前期工作发现剪切体因子USP39是SUMO的底物，进一步研究发现USP39及SUMO化位点突变的USP39影响前列腺癌细胞的增殖，但作用机制尚不清楚。本课题将通过免疫组化等手段检测前列腺癌病人标本中USP39的表达水平，结合shRNA和细胞增殖实验，进一步明确USP39与前列腺癌之间的关系；运用co-IP和shRNA敲低技术，揭示调控USP39 SUMO化的蛋白酶；通过检测SUMO化突变前后USP39功能和性质的变化，探讨SUMO化修饰影响USP39在前列腺癌发展的机制；并以动物实验证实USP39及其SUMO化修饰对前列腺癌发展的影响。此研究为治疗前列腺癌提供一个新思路和一个潜在的靶点；并通过探讨USP39 SUMO化修饰后功能改变来认识SUMO调控剪切体的机制，具有重要科学意义。

前列腺癌是一种严重威胁男性健康的疾病。研究表明,前列腺癌组织中SUMO (small ubiquitin-like modifier)特异性蛋白酶表达异常。本课题组早期工作发现剪切体因子USP39是SUMO的底物，并且发现USP39及SUMO化位点突变的USP39影响前列腺癌细胞的生长。本项目通过对野生型USP39 （USP39 WT）和SUMO位点突变后USP39 （USP39 SM）进行研究，发现USP39的SUMO位点突变后影响USP39在细胞内的定位，但并不影响其在细胞内的蛋白稳定性，也不影响其与剪切因子PRP8、PRPF3和PRPF31的相互作用。进一步的研究，通过细胞内蛋白纯化和利用质谱鉴定技术，我们发现了123个与USP39 WT特异性结合的蛋白质，以及87个与USP39 SM特异性结合的蛋白质。本项目已取得的研究成果，为后续更加深入研究SUMO化修饰影响USP39的功能以及其影响前列腺癌细胞生长的作用机制奠定了基础。此外，本项目还发现去泛素化蛋白酶USP9X通过调控PD-L1的去泛素化修饰，从而影响PD-L1的稳定性，进而影响口腔癌细胞的生长，此研究成果发表SCI论文1篇（Cancer Med. 2018 Aug;7(8):4004-4011.）。此研究结果解释了USP9X调控口腔癌细胞生长的具体机制，为把USP9X作为抗口腔癌治疗的潜在靶点提供了理论依据。