异柠檬酸脱氢酶1调控HIF通路在肾透明细胞癌中的分子机制研究

Studies have confirmed that the metabolic substrate of isocitrate dehydrogenase (IDH1), α-ketoglutarate (α-KG), could synergistically increase double oxygenase on the hypoxia inducible factor HIFα hydroxylation. Hydroxylated HIFα can be recognized and combined by ubiquitination adaptor protein VHL, which lead to the multi-ubiquitination and degradation of HIFα. In our previous study, we found that the expression of IDH1 was down regulated in clear cell renal cell carcinoma (ccRCC), and down regulated IDH1 lead to low level α-KG in ccRCC tissue. Therefore, we assume that low level α-KG caused by down regulated IDH1 is one of the most important reason HIF accumulate in ccRCC. Small molecule α-KG could suppress HIF level in ccRCC, and is a potential tumor targeted drug for ccRCC. Based on the above research and assumption, we aimed to study the function role of IDH1 in ccRCC, explore the mechanism of IDH1 on HIF in ccRCC, further research the inhibiting effect of Small molecule α-KG on ccRCC using xenograft assay. This study would illuminate the mechanism of HIF accumulated in ccRCC, which is the most important molecule etiology of ccRCC. Our study would be meaningful in providing a new therapeutic target for treatment of ccRCC.

研究证实能量代谢分子异柠檬酸脱氢酶IDH1的代谢底物α-酮戊二酸（α-KG）在细胞中能够协同双加氧酶对缺氧诱导因子HIFα的羟基化修饰，使其与泛素化接头蛋白VHL结合，从而介导了HIFα的多泛素化降解。申请者前期研究发现IDH1在肾透明细胞癌（ccRCC）中表达降低导致细胞内α-KG含量减少，据此提出假说：IDH1表达降低导致细胞内α-KG含量减少是ccRCC中HIF累积的重要原因，小分子α-KG可以降低ccRCC中HIF水平，进而可以用于治疗ccRCC。基于以上假设，本课题拟研究IDH1对ccRCC的生长抑制作用，进一步探索其作用机制，证明IDH1在ccRCC中表达降低与HIF累积的关系，最后在裸鼠肾癌模型中验证小分子α-KG对ccRCC的抑制作用。本研究有望进一步阐明HIF在ccRCC中累积的分子机制，进一步理解ccRCC发病机理，为寻找ccRCC新的治疗靶点提供新思路。

研究背景：肾细胞癌是泌尿系统常见的恶性肿瘤，晚期肾癌一线治疗方案主要为靶向治疗，HIFα及其下游信号通路是目前临床常用的治疗靶点，但是HIFα及其下游通路在肾癌中的调控机制尚不清楚。研究证实能量代谢分子异柠檬酸脱氢酶IDH1的代谢底物α-酮戊二酸（α-KG）在细胞中能够协同双加氧酶对缺氧诱导因子HIFα的羟基化修饰，使其与泛素化接头蛋白VHL结合，从而介导了HIFα的多泛素化降解。.研究内容：申请者前期研究发现IDH1在肾透明细胞癌（ccRCC）中表达降低导致细胞内α-KG含量减少，据此提出假说：IDH1表达降低导致细胞内α-KG含量减少是ccRCC中HIF累积的重要原因，小分子α-KG可以降低ccRCC中HIF水平，进而可以用于治疗ccRCC。基于以上假设，本课题拟研究IDH1对ccRCC的生长抑制作用，进一步探索其作用机制，证明IDH1在ccRCC中表达降低与HIF累积的关系，最后在裸鼠肾癌模型中验证小分子α-KG对ccRCC的抑制作用 。.研究结果：IDH1及其底物α-KG在ccRCC中显著降低；提高IDH1的表达水平，或者α-KG处理后，能够使ccRCC细胞增殖和侵袭力减弱，凋亡增加，不能产生底物α-KG的突变体IDH1R132H对ccRCC细胞表型没有明显影响；进一步通过裸鼠成瘤实验，证明了小分子α-KG对ccRCC具有明显的抑制作用，且毒副作用小。.科学意义：本研究进一步阐明了HIF在ccRCC中累积的分子机制，进一步理解ccRCC发病机理，证明了小分子α-KG用于治疗ccRCC的可行性，为寻找ccRCC新的治疗靶点提供新思路。