miR-124对丙酮酸激酶选择性表达的精密调节机制在结肠癌中的作用

Cancer glucose metabolic reprogramming is cornerstone for cancer development. Pyruvate kinase alternative expression of PKM1 or PKM2 is a key step in metabolic reprogramming. hnRNPA1，hnRNPA2 and PTB1 are responsible for alternative splicing of PKM gene to generate PKM1 or PKM2 product. Recently many studies are focused on how to regulate PKM alternative splicing. It is not clear whether microRNA, involved in many gene regulation, target the PKM alternative splicing. microRNA profiling indicated that miR-124 was correlated with prognosis of colon cancer. Lower expression of miR-124 was found in poor prognosis of colon cancer samples. In vitro experiments, it also demonstrated that miR-124 inhibited the growth of colon cancer cell. Bioinformatics analysis indicated that hnRNPA2 and PTB1 were potential targets of miR-124. Our hypothesis is that miR-124 inhibits colon cancer growth through PKM alternative splicing meditated glucose metabolic reprogramming. In this study we will focus on: understanding the role of miR-124 in cancer growth and glucose metabolism by mouse colon cancer xenograft model, analyzing the mechanism of miR-124 involved in regulation of pyruvate kinase alternative splicing, discovering the PKM1/HNF4α positive feedback loop in regulation of miR-124 expression. Therefore our research will elucidate miR-124, as a master anti-oncogene regulator of colon cancer glucose metabolism, should be a useful marker of personalized colon cancer therapy.

肿瘤糖代谢重编程是包括结肠癌在内肿瘤发生发展的基石，而hnRNPA1，hnRNPA2和PTB1介导的丙酮酸激酶（PKM）选择性表达PKM1或PKM2是其中关键步骤，如何调控PKM表达成为近来研究热点。前期研究通过结肠癌microRNA表达谱分析，发现预后差的病例中miR-124显著低表达，且miR-124能抑制结肠癌细胞生长；生物信息学分析发现hnRNPA2和PTB1是miR-124的靶基因。故研究假设：miR-124与PKM选择性表达相关，通过糖代谢重编程发挥抑制结肠癌生长的作用。本课题拟：评估miR-124对结肠癌进展及糖代谢的作用；分析miR-124对PKM选择性表达的调节机制；探索PKM1/HNF4α促进miR-124表达的正反馈机制。以阐明miR-124在结肠癌糖代谢重编程中的作用及机制，建立以miR-124为核心的基于糖代谢调控的抑癌模式，为其在结肠癌中的应用提供理论依据。

肿瘤细胞不论氧浓度高低均以糖酵解的方式代谢葡萄糖，用以提供大分子合成原料、提供能量及维系氧化还原，该现象被称为有氧糖酵解（Warburg效应）。近年来发表于Nature、Science和Cell等杂志关于PKM2（2型丙酮酸激酶）在Warburg效应中的关键作用的突破性研究成果，使PKM2成为肿瘤葡萄糖代谢研究和临床转化的核心基因，而hnRNPA1，hnRNPA2和PTB1介导的丙酮酸激酶（PKM）选择性表达PKM1或PKM2是其中关键步骤，如何调控PKM表达成为近来研究热点。本项目旨在探讨miR-124, miR-137和 miR-340对结肠癌糖代谢的作用，并阐述PKM选择性表达的调节机制，据此发掘逆转肿瘤葡萄糖代谢异常的治疗靶点。应用III期结肠癌且生存期差异病例miRNA表达谱，结合 miRNA靶向基因预测数据库，我们发现miR-124, miR-137和 miR-340同结肠癌的预后呈负相关。这些miRNA 则通过靶向选择性剪接蛋白PTB1/hnRNAPA1/hnRNAPA2，抑制PKM2表达的同时促进PKM1的表达，由此促使糖代谢趋于正常化进而抑制肿瘤细胞的生长。进一步研究我们发现PKM1可作为HNF4α转录因子的共激活因子促进miR-124的表达，进而发挥对Warburg效应及肿瘤发生发展的调节。这种正反馈调节机制凸显miR-124靶向葡萄糖代谢遏制肿瘤发生发展的重要作用，为miR-124在肿瘤治疗中的应用奠定了理论基础。上述研究阐明了miR-124、miR-137和 miR-340通过调节PKM选择性表达调节Warburg效应发挥抑癌作用的机制，阐述了miR-124与PKM1/HNF4α相互促进表达的正反馈调控机制以及该调控环在结肠癌生长调控中的作用，从而建立以miR-124为核心的抑癌模型，从而从代谢的角度为结肠癌诊治提供新思路和新方法。.本研究发表标注课题资助号的SCI论文2篇，未标注论文2篇，尚有文章正在投稿中。研究成果主要发表于Oncol Rep（2012，IF：2.301分，引用：45次）和Int J Mol Sci（2014，IF：2.862分，引用：3次）杂志。本项目联合培养博士1名、硕士1名。