FOXM1线粒体转位诱导糖代谢重编程促胃癌侵袭转移的作用及分子机制研究

Previous studies mainly focused on the transcription regulation functions of FOXM1 in tumor invasion and metastasis. Interestingly, recent study and our research found that FOXM1 promoted the invasion and metastasis of gastric cancer independent of its transcription function, but the mechanism is not clear. We demonstrated that FOXM1 translocated into mitochondria in gastric cancer cells. Combined with bioinformatics and mutation technique, we clarified the mitochondrial localization sequence (MTS) of FOXM1. The invasion and metastasis of gastric cancer cells was significantly reduced after the MTS mutation of FOXM1. Further study showed that mitochondrial FOXM1 induced the generation of ROS, enhanced the glucose metabolism reprogramming and promoted the production of lactic acid. The mass spectrometry analysis showed that FOXM1 may binds to the mitochondrial respiratory chain complex. So we propose the hypothesis that the mitochondrial FOXM1 binds to the respiratory chain complex, which induces glucose metabolism reprogramming and promotes gastric cancer invasion and metastasis". The detailed mechanism of the binding of FOXM1 and respiratory chain complex will be analyzed by Co-IP, FRET and other molecular methods. Furthermore, we will elucidate the role and mechanism of FOXM1 independent of its transcriptional regulation, the binding between FOXM1 and the respiratory chain complex would also be validated at molecular levels in cells and nude mice. This study will provide more knowledge on the mechanism of the FOXM1-mediated invasion of cancer cells. The demonstration of the hypothesis will provide the theoretical basis for the design of antitumor drugs targeting FOXM1.

既往研究聚焦于FOXM1转录调控功能在肿瘤侵袭转移中的重要作用，新近研究及本课题组预实验发现FOXM1还可非依赖转录功能促胃癌侵袭转移,但机制不清。课题组证实FOXM1可转位于胃癌细胞线粒体，结合生物信息学及点突变，解析了FOXM1的线粒体定位序列(MTS),突变MTS后FOXM1线粒体转位显著减少,促胃癌侵袭转移明显减弱。课题组发现线粒体FOXM1促ROS生成、糖代谢重编程及酸性微环境构筑,质谱分析提示FOXM1可与线粒体呼吸链复合物结合.据此提出“线粒体FOXM1通过结合呼吸链复合物诱导糖代谢重编程促胃癌侵袭转移”的假说.课题组拟采用Co-IP,FRET等分子生物学技术,阐明FOXM1与呼吸链复合物互作分子基础,从分子,细胞,动物及临床标本不同层面验证FOXM1与呼吸链复合物结合影响胃癌侵袭转移的作用,丰富FOXM1促胃癌侵袭转移的分子机制,为靶向FOXM1的抗癌药物设计提供理论依据。

Forkhead Box M1 (FOXM1) 在肿瘤发生和发展中起重要作用, 然而关于FOXM1细胞的亚定位与其功能的关系，以及如何靶向FOXM1降解从而发挥抗癌作用研究较少。本课题发现过表达CDK能够显著促进TOMM22的磷酸化，进而促进FOXM1与TOMM22结合，导致线粒体FOXM1转位增加；反之，加入CDK的抑制剂抑制了TOMM22蛋白磷酸化，进而抑制FOXM1与TOMM22结合，导致FOXM1的线粒体转位减少。线粒体FOXM1明显抑制线粒体氧化磷酸化，糖代谢明显改变，从而促进胃癌细胞侵袭转移。此外，采用 ON-TARGET plus siRNA 文库筛选靶向 FOXM1 的潜在 E3 泛素连接酶，进一步应用细胞集落形成和Transwell来检测细胞生长和侵袭。结果表明新的E3连接酶RNF112在胃癌中可直接泛素化降解 FOXM1。RNF112可以限制抑制FOXM1转录网络，在体外和体内抑制胃癌的增殖和转移。机制研究进一步表明RNF112 (1-147aa) 的 N 端结构域与 FOXM1 结合并介导 FOXM1 的泛素化，存在直接的酶-底物催化关系。此外，RNF112是胃癌组织中与FOXM1相关的最负相关的E3连接酶。此外，小分子化合物RCM-1显着增强了FOXM1和RNF112之间的相互作用，进一步发挥了很好的抗肿瘤作用。我们的研究证实了 FOXM1 的新型 E3 连接酶 RNF112 通过泛素化 FOXM1 来抑制胃癌的进展，这表明 RNF112-FOXM1 轴可能是对抗胃癌病理作用的新治疗靶点。