RIPK4通过磷酸化修饰SIK2调控卵巢癌代谢重编程的机制研究

代谢异常是肿瘤细胞最显著的特征之一。临床发现卵巢癌易在网膜等脂肪丰富的组织和器官上种植转移。研究提示在脂肪丰富器官的转移灶上高表达的蛋白可能在代谢调控中发挥重要作用。前期通过高通量方法筛选发现激酶RIPK4在网膜转移灶上高表达。前期体内和体外研究结果显示，降表达RIPK4后，卵巢癌细胞的脂肪酸氧化和Warburg效应受到抑制，卵巢癌的网膜转移能力降低。免疫共沉淀提示RIPK4与卵巢癌代谢调控关键分子SIK2相互作用。降表达RIPK4后，SIK2的磷酸化水平显著降低。因此本课题提出假设：RIPK4通过磷酸化修饰SIK2促进卵巢癌代谢重编程。为验证这一假设，本课题拟首先通过体内外实验验证RIPK4的表达对卵巢癌糖代谢、脂代谢、mTOR信号通路活化等表型的影响；其次通过体外磷酸化、氨基酸位点突变等实验阐明RIPK4磷酸化底物蛋白SIK2的精细机制。本课题将为卵巢癌的临床诊断及治疗提供新的思路。

Aberrant metabolism and metabolic reprogramming represent malignant tumor hallmarks. It is found that ovarian cancer cells metastasize almost exclusively to the adipocyte-rich environment in the abdominal cavity. Previous studies have indicated that proteins highly expressed in adipocyte-rich metastases probably play an important role in metabolic regulation. We have shown that kinase RIPK4 is overexpressed in adipocyte-rich omentum metastatic deposits compared to ovarian primary lesions. Previous in vitro and in vivo studies indicated that silencing RIPK4 significantly suppressed fatty acid oxidation, the Warburg effect and adipocyte-rich metastatic potential. It was found by co-immunoprecipitation that RIPK4 interacts with SIK2, which is a key regulator of metabolic reprogramming in ovarian cancer. In addition, the phosphorylation level of SIK2 significantly decreased when RIPK4 silenced in our earlier work. Therefore, we are hypothesizing that RIPK4 promotes ovarian cancer cell metabolic reprogramming by phosphorylating SIK2. Firstly, we will propose to use plenty of in vitro and in vivo assays to explore the impacts on ovarian cancer cell metabolism phenotypes of RIPK4 expression. Secondly, co-immunoprecipitation, GST-pulldown, in vitro phosphorylation assay, point mutation and other experiments will be done to illuminate specific molecular mechanism. Our study, for the first time, will illustrate the mechanism of how RIPK4 promotes ovarian cancer cell metabolic reprogramming by phosphorylating SIK2 and provide a possible treatment for ovarian cancer.