Fbxw7通过调控PKM2泛素化蛋白酶解抑制胶质瘤细胞糖酵解及侵袭转移

The pathogenesis of glioblastoma is not fully understood as yet. Our previous study indicated that Fbxw7 was an independent prognostic marker and it induced cell apoptosis and inhibited proliferation in glioma cells, but the exactly mechanism is still unclear. PKM2, which is known as a key factor in tumor metabolism, is also found took part in non-metabolic pathway. Our previous study showed that Fbxw7 was negatively correlated with PKM2 protein in glioma tissues and Fbxw7 regulated PKM2 expressionin glioma cells. We found that there was an interaction between PKM2 and Fbxw7 by using co-immunoprecipitation assay. And mass spectrometric analysis further revealed there was a canonical phosphodegron in PKM2, by which PKM2 could be recognized by Fbxw7. Our purpose is try to find out whether if Fbxw7 functions as a tumor suppressor by ubiquitination and proteasomal degradation of PKM2 protein. Besides, we attempt to verify the mechanisms involved in ubiquitination and regulation of PKM2 protein by Fbxw7 through gene mutagenesis. The aim of this project is to investigate the molecular mechanisms of both the anti-cancer effect of Fbxw7 and abnormal activation of PKM2 protein in glioma cells, in order to provide further scientific basis for novel targeting agents and predictive biomarkers.

目前脑胶质瘤的发病机制仍然不清楚，对于其细胞内部代谢异常及向周围侵袭转移的分子机制仍有待进一步研究。课题组前期证明Fbxw7是一个独立的胶质瘤患者预后标志物，Fbxw7具有促进胶质瘤细胞凋亡和抑制增殖作用，但其具体分子机制不清。而PKM2不仅在肿瘤代谢中起作用，其也参与了肿瘤非代谢途径，但具体机制仍不明确。课题组前期研究发现胶质瘤组织中Fbxw7与PKM2蛋白表达负相关，胶质瘤细胞中Fbxw7蛋白负调控PKM2蛋白，免疫共沉淀发现Fbxw7与PKM2蛋白存在相互作用，进一步质谱分析发现PKM2蛋白存在Fbxw7结合的经典磷酸决定子。本研究拟通过体内外实验证明Fbxw7通过泛素化蛋白酶解PKM2发挥其抑癌作用并探讨Fbxw7泛素化PKM2的具体分子机制。本项目旨在阐明Fbxw7抗癌作用的具体机制及PKM2在胶质瘤患者体内异常活化的分子机制，为临床上开发新的预后标志物及靶向药物提供依据。

脑胶质瘤是最常见的原发性颅内恶性肿瘤，侵袭性生长的生物学特性使其治疗效果不尽理想。因此，阐明脑胶质瘤发生发展的分子机制有助于临床上研发有效的靶向治疗药物和肿瘤诊断及预后标志物。本项目探索胶质瘤中泛素连接酶Fbxw7对PKM2蛋白异常的调控作用，旨在明确胶质瘤中低表达的Fbxw7是否PKM2蛋白异常表达的原因以及Fbxw7抗胶质瘤的作用机制，为进一步的基础研究提供理论基础和前期资料，最终为开发相关的抗胶质瘤靶向生物学治疗药物提供帮助。本项目研究结果提示：Fbxw7是一个独立的胶质瘤患者预后标志物；Fbxw7促进胶质瘤细胞凋亡和抑制增殖；胶质瘤组织中Fbxw7与PKM2蛋白表达负相关，胶质瘤细胞中Fbxw7蛋白负调控PKM2蛋白；免疫共沉淀发现Fbxw7与PKM2蛋白直接结合，Fbxw7促进PKM2泛素化蛋白酶解，PKM2 Ser37位点磷酸化在此过程中发挥关键作用；Fbxw7通过靶向泛素化降解PKM2发挥抗胶质瘤作用。本项目阐明了Fbxw7抗癌作用的具体机制及PKM2在胶质瘤患者体内异常活化的分子机制，为临床上开发新的预后标志物及靶向药物提供依据。