缺氧诱导的circMYH9通过ATF4调控结直肠癌干性和化疗敏感性的作用和机制研究

既往研究证实，缺氧能增强结直肠癌（CRC）干性并抑制其化疗敏感性。而circRNA在其中的作用则未见报道。我们发现：内含子来源的circMYH9在上述过程中发挥关键作用，HIF-1α和ATF4是其上下游调控分子。circMYH9调控ATF4依赖于抑制hnRNPC与ATF4前体RNA m6A位点结合；ATF4具有招募KMT2b在转录水平增强干性标志分子表达功能。据此提出假说：缺氧通过HIF-1α介导circMYH9升高，circMYH9通过ATF4调控CRC干性和化疗敏感性。拟开展：①研究缺氧下circMYH9的功能与表达升高原因，从m6A修饰和组蛋白甲基化修饰角度研究circMYH9通过ATF4调控干性标志分子的机制；②评估裸鼠体内抑制circMYH9的治疗效果；③在CRC组织中研究上述分子的临床意义。本研究从circRNA角度为缺氧促进CRC发展的机制研究和阻断治疗提供了新思路和新靶点。

Previous studies have confirmed that hypoxia can enhance the stemness of colorectal cancer (CRC) and inhibit its chemotherapy sensitivity. The role of circRNA in the above process has not been reported. We found that intron-derived circMYH9 plays a key role in the above process, and HIF-1α and ATF4 are its upstream and downstream regulatory molecules. CircMYH9 regulating ATF4 depends on inhibiting the binding of hnRNPC to the m6A site of ATF4 precursor RNA; ATF4 recruits KMT2b to enhance the expression of stem marker molecules at the transcription level. Accordingly raise the hypothesis: hypoxia mediates the increase of circMYH9 through HIF-1α, and circMYH9 regulates CRC stemness and chemotherapy sensitivity through ATF4. To be carried out: ① To study the function of circMYH9 and the cause leading to its overexpression under hypoxia, and to study the mechanism of circMYH9's regulation of stemness markers through ATF4 from the perspective of m6A modification and histone methylation modification; ② To evaluate the therapeutic effect of inhibiting circMYH9 in nude mice；③ To study the clinical significance of the above molecules in CRC tissues. From the perspective of circRNA, this study provides new ways for the study of the mechanism of hypoxia to promote CRC and new targets for the blocking treatment.