基于let-7a/KRAS/MYC/HnRNPA1反馈环路解析PKM2调控胶质瘤细胞糖代谢与生长的机理

Up to now, tumor metabolism has become one of the hot topics in cancer research. Our data showed that down-regulation of PKM2 and up-regulation of let-7a inhibited glioma cell glycine metabolism and growth. Up-regulation of let-7a also reduced the expression of its target genes (KRAS and MYC) and the downstream genes (HnRNPA1 and PKM2). Further, reduction of HnRNPA1 inhibited PKM2 expression, whereas induced let-7a expression. Thus, we proposed the hypothesis that PKM2 regulation network based on let-7a/KRAS/MYC/HnRNPA1 feedback loop plays a key role in glioma glycine metabolism and growth. In the future study, we will choose glioma cells with different gene backgrounds (EGFR、PTEN and IDH1) as cell models and transcriptional regulation, posttranscriptional regulation and gene rescue as major methods, evaluate the effect of PKM2 regulation network based on let-7a/KRAS/MYC/HnRNPA1 feedback loop on glioma glycine metabolism and growth, further analyze the role of key notes in glioma molecular diagnosis, prognosis evaluation and targeting therapy. In conclusion, our finding will reveal the role and mechanism of PKM2 regulation network based on let-7a/KRAS/MYC/HnRNPA1 feedback loop in glioma glycine metabolism and growth, and provides more potential approaches for glioma treatment.

目前肿瘤细胞代谢已成为肿瘤研究的热点。我们预实验发现：下调PKM2和上调let-7a能有效抑制胶质瘤糖酵解和生长；上调let-7a可抑制靶基因KRAS和MYC及下游HnRNPA1与PKM2表达；敲低HnRNPA1能下调PKM2而上调let-7a。据此提出假说：let-7a/KRAS/MYC/HnRNPA1环路调控PKM2信号在胶质瘤糖代谢与生长中发挥重要作用。本课题拟以EGFR、PTEN与IDH1不同状态的胶质瘤细胞为模型，以转录调控、转录后调控、基因回复等为手段,全面分析let-7a/KRAS/MYC/HnRNPA1环路调控PKM2的网络及其对胶质瘤糖代谢与生长的影响，分析关键节点在胶质瘤分子诊断、预后判断及靶向治疗中的作用。本课题将揭示不同遗传背景下基于let-7a/KRAS/MYC/HnRNPA1反馈环路的PKM2网络对胶质瘤糖代谢与生长的作用与机理，为寻找胶质瘤新治疗靶点奠定基础。

肿瘤能量代谢方式的改变已被列肿瘤的十大特征之一，肿瘤细胞代谢的研究已经成为当今肿瘤研究的热点。本项目中阐释RNA let-7a对胶质瘤细胞增殖和糖代谢水平的影响及机理，重点研究两者间的相互调控关系，建立分子反馈环路。研究证实：在脑胶质瘤细胞中PKM2特异性过表达，且表达高低与胶质瘤病理恶性程度相关，干扰PKM2表达可显著抑制胶质瘤的增殖和代谢能力。在胶质瘤细胞中，let-7a可直接靶向c-Myc，c-Myc促进hnRNPA1的转录而影响PKM2的表达和胶质瘤细胞糖代谢能力，HnRNPA1促进pkm2的剪切生成影响胶质瘤细胞糖代谢水平，同时HnRNPA1抑制Drosha酶介导的let-7a的生成，综上所述，let-7a、c-Myc、HnRNPA1三者之间存在反馈环路（而KRAS与该反馈环路间的关系并不显著），影响胶质瘤细胞糖代谢和生长能力。上述结果得到回复实验和体内实验结果验证。同时，在衍生研究中，项目组发现核转录因子P65通过直接上调PKM2的表达影响人脑胶质瘤细胞的生长和葡萄糖代谢，P65-PKM2介导了PPARα激活剂非诺贝特对人脑胶质瘤细胞糖酵解能力的抑制作用。项目的研究结果为胶质瘤的分子诊断、预后判断及优化治疗方案的制定提供了理论依据。