Girdin通过肿瘤代谢对肺癌化疗疗效的影响及其机制研究

The PI3K-Akt pathway is one of the most commonly deregulated signaling pathways in human cancers. The AKT substrate Girdin has a critical role in cancer metastasis and proliferation. However, the role of Girdin in cancer chemotherapy is poorly understood. Our preliminary studies indicated that Girdin was overexpressed in lung cancer tissues. Overexpreesion of Girdin in H1299 cells inhibited cisplatin-induced apotosis. Through a proteomic approach to screen Girdin-interacting proteins, we found that Girdin interacted with pyruvate kinase M2 (PKM2), which is a key regulator of altered cancer metabolism in lung cancer cells. Knockdown of Girdin by siRNA led to the decreased phosphorylation of PKM2 at tyrosine 105, which suppressed the ATP production in lung cancer cells. Given that cancer metabolism contributes a lot to tumorigenesis and chemotherapy, we hypothesize that Girdin regulates cancer metabolism and proliferation through the interaction with PKM2, which further affects chemotherapy. To test this hypothesis, several approaches such as co-immunoprecipitation, western bolt, immunofluorescence, and RNA interference using cultured cancer cells and the histological analysis of cancer tissue sections will be applied to investigate the role of Girdin-PKM2 interaction in cancer metabolism and proliferation, as well as its involvement in the resistance against chemotherapy. In addition, we will evaluate the possibility for application of Girdin as a potential clinical prognosis marker for lung cancer.

PI3K-AKT信号通路组成部分发生突变在肿瘤中极为常见，其中AKT底物Girdin对肿瘤的转移和增殖至关重要。但Girdin是否调节肿瘤的化疗疗效目前尚不清楚。我们前期结果显示Girdin在肺癌组织中高表达，过表达Girdin能够抑制顺铂诱导的肺癌细胞凋亡。并用蛋白质组学方法检测出Girdin与调节肿瘤代谢的关键蛋白丙酮酸激酶2（PKM2）结合，敲除Girdin导致肺癌细胞PKM2第105位酪氨酸磷酸化水平下降以及ATP合成减少。由于代谢异常在肿瘤增殖和化疗中起到关键作用，据此我们推测：Girdin通过和PKM2结合调节肿瘤代谢过程进而促进肿瘤增殖影响化疗疗效。本课题将采用免疫共沉淀、免疫印迹、免疫荧光染色和临床标本分析等手段阐明Girdin通过结合PKM2调节肿瘤代谢的机制，探讨Girdin对肺癌化疗疗效的影响，评估其作为一种判断临床预后的指标的可能性。

PI3K-AKT信号通路组成部分发生突变在肿瘤中极为常见，其中AKT底物Girdin对肿瘤的转移和增殖至关重要。但Girdin是否调节肿瘤的化疗疗效目前尚不清楚。我们利用蛋白质组学方法检测出Girdin与调节肿瘤代谢的关键蛋白丙酮酸激酶2(PKM2)结合，细胞学实验证明在肿瘤细胞中Girdin N端和PKM2结合。敲除Girdin导致肺癌细胞ATP和乳酸合成减少、葡萄糖消耗减少，证明其参与肿瘤糖酵解代谢。接着我们发现Girdin通过PDGFR信号通路调节PKM2磷酸化。Girdin敲除使得PKM2第105位酪氨酸磷酸化水平显著下降并且由此导致PKM2酶活性增强。Girdin通过肿瘤代谢途径调节肺癌细胞对于化疗药物的敏感性。进一步的临床标本分析发现在肺癌组织中Girdin和PKM2的表达相关，并且都和肺癌淋巴结转移相关。由以上结果我们得出结论：Girdin结合并且通过调节PKM2磷酸化和酶活性参与肿瘤代谢，并由此调节肺癌细胞对化疗的敏感性，参与肺癌的进展和转移，在未来可能作为一种潜在的治疗诊断靶点。