维生素C通过DNA羟甲基化调节尿路上皮癌化疗敏感性的分子机制研究

尿路上皮癌（urothelial carcinoma，UC）是泌尿系统最常见的恶性肿瘤之一，易发生复发和转移。进展期UC常予以基于顺铂的新辅助或辅助化疗方案，但是多数患者仍面临化疗耐药和毒性反应的问题。本课题组前期研究发现：基因组羟甲基化（5hmC）在UC中缺失，其缺失程度和不良预后密切相关；维生素C可提高5hmC水平，特异性发挥抑癌作用。同时发现维生素C可提高UC细胞顺铂化疗的敏感性，UC患者化疗敏感性和肿瘤5hmC水平显著相关。为探究维生素C提高5hmC调节UC化疗敏感性的分子机制，本项目拟①通过细胞学和动物实验探索维生素C联合化疗对UC化疗敏感性的生物学作用；②整合分析不同处理组全转录组测序和基因组羟甲基化测序结果，筛选和鉴定5hmC调节化疗敏感度的关键靶基因，开展分子生物学实验。以此解析维生素C提高5hmC水平调节UC化疗敏感度的具体分子机制，为UC治疗提供新的化疗方案。

Urothelial carcinoma (UC) is one of the most commonly diagnosed cancer, more likely to relapse and progression. Advanced urothelial carcinoma could be treated with cisplatin-based neoadjuvant or adjuvant chemotherapy, but most patients are faced with problems of drug-resistance and adverse reactions to chemotherapy. Our previous study found that 5-Hydroxymethylcytosine (5hmC) is downregulated in urothelial carcinoma, and the deletion of 5hmC is closely related to poor prognosis; ascorbate could improve the level of 5hmC, and inhibit the growth of tumor cells but does not affect normal urothelium cells. To explore the relationship between ascorbate regulating 5hmC and cisplatin-based chemotherapy sensitivity of urothelial carcinoma, this study intends to explore the effect of ascorbate combined with chemotherapy drugs on DNA damage and apoptosis of urothelial carcinoma cells. Secondly, xenograft mice model of urothelial carcinoma is established to detect the effects of different conbination of drugs on the growth of xenograft tumor. Next, Integrated analysis of whole transcriptome resequencing and DNA hydroxymethylation sequencing is performed to screen and identify key gene relevant to the sensitivity of cisplatin-based chemotherapy. Finally, molecular biology experiments are carried out to explore the specific mechanism that ascorbate improve chemotherapy sensitivity. Seeking the novel combination of cisplatin-based chemotherapy and revealing the underlying mechanism would provide new chemotherapy regimens for urothelial carcinoma patients.