Wnt/β-catenin通路促进HSF1蛋白翻译合成的分子机制及其在结直肠癌中的作用

m6A修饰和微小RNA结合都可以调控mRNA翻译，但两者间的相互作用不详；热休克转录因子HSF1在结直肠癌中发挥重要作用，但其表达调控机制未明。我们发现与结直肠癌发病密切相关的Wnt通路可促进HSF1翻译，而miR455-3p则抑制HSF1翻译；结合miR455-3p的HSF1 mRNA序列中含有m6A修饰位点；敲低β-catenin或m6A修饰催化酶METTL3后，HSF1 mRNA的m6A修饰减少，同miR455-3p的结合则增加，HSF1蛋白表达下降，因此wnt/β-catenin通路可能通过协调miR455-3p结合和m6A修饰间的相互拮抗来激活HSF1翻译，促进结直肠癌发生。本项目将着重分析m6A修饰和miR455-3p结合对HSF1翻译的调控作用，探索Wnt通路促进HSF1表达的分子机制，研究该调控轴在结直肠癌发病中的作用及其转化价值，从而为结直肠癌等恶性肿瘤的防治提供新思路。

Both the m6A modification of mRNA and microRNA can regulate the translation of mRNA into protein. However, the interaction of mRNA m6A modification and microRNA in translation regulation remains unknown. Recently, we reported that heat shock transcription factor 1 (HSF1) contributed to colorectal carcinogenesis by promoting glutaminolysis (Molecular Therapy 2018). However, the underlying mechanism responsible for the upregulation of HSF1 expression in colorectal carcinogenesis is still unknown. In the preliminary investigations for this proposed study, we found that Wnt/β-catenin signaling, which is critical to colorectal carcinogenesis, can promote HSF1 mRNA translation while the microRNA miR455-3p was able to suppress HSF1 mRNA translation. Interestingly, there is a typical m6A modification motif (GGACU) in HSF1 mRNA 3’-UTR region pairing with miR455-3p seed sequence. In addition, m6A RNA immunoprecipitation indeed enriched a peak around this region. Depleting β-catenin or METTL3, the critical enzyme responsible for mRNA m6A modification, decreased HSF1 mRNA m6A modification, increased the interaction of HSF1 mRNA with miR455-3p and suppressed HSF1 protein expression. Therefore, we hypothesized that Wnt/β-catenin signaling promotes HSF1 mRNA translation during colorectal carcinogenesis by coordinating the interaction between miR455-3p binding and HSF1 mRNA m6A modification on HSF1 mRNA translation. To prove it, we planned to analyze the influence of miR455-3p and HSF1 mRNA m6A modification on HSF1 mRNA translation, and explore the regulation of miR455-3p and HSF1 mRNA m6A modification by Wnt/β-catenin signaling. By doing so, this proposed study will exposit the regulation of mRNA translation, uncover a new function of Wnt/β-catenin and provide new insights to design effective approaches for the intervention of colorectal cancer as well as other cancers.