肾透明细胞癌是肾癌中最主要的病理亚型，易发生术后复发和转移。肾透明细胞癌以胆固醇等脂质堆积为主要特征，然而其具体机制尚不清楚。本课题组前期研究发现基因组羟甲基化（5hmC）修饰可调节肾透明细胞癌中胆固醇代谢相关基因表达，调节胆固醇含量；而5hmC在肾透明细胞癌组织中缺失，且缺失程度与肿瘤分期分级和不良预后密切相关。以此我们推测，5hmC缺失可能通过调节胆固醇代谢促进肾透明细胞癌进展。本项目拟①整合分析RNA-seq和TAB-seq测序结果并开展分子生物学等实验，鉴定5hmC调节胆固醇代谢的关键靶基因；②干预靶基因表达，检测其对5hmC调节胆固醇代谢和细胞增殖、凋亡和浸润能力的影响；③构建人源化肾透明细胞癌移植瘤模型，检测干预5hmC含量和胆固醇代谢对移植瘤生长转移情况的影响。以此解析5hmC缺失通过调节胆固醇代谢促肾透明细胞癌的具体机制，为肾透明细胞癌的精准靶向治疗提供理论基础。

Clear cell renal cell carcinoma (ccRCC) is the most common subtype of kidney cancer and has the highest propensity to manifest as metastatic disease. ccRCC is characterized by accumulation of lipids such as cholesterol, however, the mechanisms and tumor promotion effect are still unclear. Our previous results proved that 5-hydroxymethylation of cytosine in genome DNA is defect in ccRCC tissues, and the loss of 5-hydorxymethylcytosine is related to higher tumor stage and grade and worse prognosis. The latest studies showed that upregulation of 5hmC could inhibit the expression of cholesterol metabolic genes, and regulated accumulation of lipids such as cholesterol. So we assumed that loss of 5hmC may promote ccRCC progression by regulating cholesterol metabolism. Firstly this project will analyze the results of RNA-seq and TAB-seq and carry out molecular biologic experiments such as chromosome immunoprecipitation (ChIP) to identify the target gene of 5hmC regulating cholesterol metabolism. Secondly we will interfere the expression of the target gene and evaluate the effects on cholesterol metabolism and cell growth, apoptosis and invasion. Thirdly we will establish the Patient-Derived tumor Xenograft model of ccRCC and test the influence of 5hmC and cholesterol metabolism interference on tumor growth and metastasis. This study will clarify the mechanism of 5hmC loss promoting ccRCC progression by regulating cholesterol metabolism and provide theoretical basis for precision targeting therapy on ccRCC.