EZH2靶向SIRT3调控糖酵解促进结直肠癌恶性潜能的机制研究

Research on the regulatory mechanism of development and metabolism in colorectal cancer is in the ascendant. Our group previouly found EZH2 gene is at an important position of the tumor regulation network, whereas how EZH2 promote the malignant potential of colorectal cancer cells is not clear. We found that EZH2 can promote tumor cell glycolytic uptake and lactate production; RNA-sequencing results showed that a tumor glucose metabolism inhibitor, SIRT3, may be a target gene of EZH2, and silencing EZH2 expression can induce SIRT3 expression in colorectal cancer cells; meanwhile, we also found a significant negative correlation between EZH2 expression and SIRT3 expression in clinical patient tissues. Therefore, we speculated that there is a "EZH2 ┫SIRT3-aerobic glycolysis" regulatory axis in colorectal cancer. In the present, project will be based on the previous results, found the function of EZH2 in malignant potential of colorectal cancer through the construction of EZH2 gene overexpression and shRNA vector; identify the mechanism of EZH2 on targeting SIRT3 and regulated glycolysis using a series of genetic interference; and explore the expression and clinical value of related molecules in clinical samples. This study can shed light on the function and mechanism of EZH2 in tumorigenesis, and provide a theoretical basis and a new direction for accurate treatment of colorectal cancer.

结直肠癌的代谢调控机制研究方兴未艾。我们前期发现EZH2基因在肿瘤调控网络中处于重要地位，EZH2促进结直肠癌细胞恶性潜能机制尚待阐明。我们在结直肠癌中研究发现EZH2可促进肿瘤细胞糖酵解摄取和乳酸生成，通过RNA-seq筛选发现肿瘤糖代谢抑制因子SIRT3可能是EZH2的靶基因，且沉默EZH2表达可诱导细胞中SIRT3表达；同时，在临床患者的组织中，EZH2的表达与SIRT3的表达显著负相关。据此推测结直肠癌中存在“EZH2┫SIRT3-有氧糖酵解”调控轴。本项目将在前期基础上，通过构建EZH2基因过表达和shRNA载体研究其在结直肠癌恶性潜能中的功能；利用一系列分子生物学技术鉴定其靶向SIRT3调控有氧糖酵解促进结直肠癌细胞恶性潜能的具体机制；探索相关分子在临床样本中的表达及临床转化价值。本研究可丰富EZH2在肿瘤发生发展中的功能及机制理论，为肠癌的精准治疗提供理论依据和新的方向

结直肠癌中表观遗传介导的代谢调控机制研究是一直以来的热点及难点。本课题按原计划对EZH2 / SIRT3调控轴在肠癌有氧糖酵解和恶性潜能中具体作用及其调控机制进行研究。主要完成了以下研究内容：①EZH2表达水平高低可作为临床病理监测结直肠癌患者进展并预测肿瘤患者预后的重要的参考指标之一。② EZH2对肠癌细胞的多方面恶性潜能具有促进作用，包括其代谢功能（有氧糖酵解和乳酸积累）、生长周期、增殖､迁移和转移能力；同时我们认为EZH2在结直肠肿瘤中的上调可能是肠癌恶性发展的促进因素而非伴随现象。③Prox1与EZH2是相互作用蛋白，可以募集EZH2到SIRT3基因启动子区域的染色质区域进而抑制SIRT3的表达 ④ EZH2表达高低与反应肿瘤代谢能力大小的影像学指数SUVmax密切相关。同时SIRT3在癌中表达显著低于于癌旁正常组织，且与SUVmax负相关，实验证明其可负向调控代谢负荷。 ⑤Prox1在结直肠癌中的生物学功能，提示Prox1反应了肠癌的恶性表型，且在临床标本中，与SIRT3的表达负相关。在结直肠癌细胞中存在着EZH2/Prox1这一功能复合体，这个复合体可调控SIRT3的表达，进而影响结直肠癌细胞的代谢异常。我们的研究了EZH2、PROX1和SIRT3等分子在肠癌中的功能和相互作用机制，提示这些分子可能研制成为新的肠癌治疗靶点，本课题拓展了对肠癌恶性表型相关调控机制和EZH2、PROX1、SIRT3在肠癌癌中的作用及下游分子机制的认识；同时也为癌蛋白EZH2在肠癌中调控机制提供了新的研究视角和基础实验依据｡本课题有助于寻找新的肠癌预后监测分子标志物和分子治疗靶标，具有良好的理论意义和临床转化价值｡