Circular RNAs (circRNAs) play important roles in cancer progression and metabolism regulation. Serine/glycine metabolism supports the growth of cancer cells by contributing to their anabolic demands and epigenome as well as by regulating their redox state. However, the role of circRNA in the regulation of serine/glycine metabolism has not been well elucidated. Microarray analysis was used to screen differentially expressed novel circRNAs. qRT-PCR and FISH were utilized to analyzed the expression of circMYH9. CCK8, colony formation and FACS were used to analyze proliferation of colorectal cancer (CRC) cells. Xenograft experiments were used to analyze tumor growth in vivo. RNA-sequencing, immunoblot and LC–MS were used to identify the downstream metabolic pathway of circMYH9. ChIRP, Mass Spectrometry, RIP and RNA pulldown were utilized to test the interaction between circMYH9, hnRNPA2B1 and p53 pre-mRNA. ChIP-qPCR was used to analyze the binding sites of HIF-1α. Chemically-induced CRC mice were generated to evaluate the role of circMYH9 in tumorigenesis. We identified an intron-derived circRNA, circMYH9, which was significantly upregulated in CRC tissues. A higher circMYH9 level correlated with shorter relapse-free survival and overall survival of CRC patients. CircMYH9 promoted serine/glycine metabolism, the NAD + /NADH ratio, and glutathione recycling and inhibited reactive oxygen species (ROS) in a p53-dependent manner, impacting tumour growth. Mechanistically, circMYH9 destabilized the pre-mRNA of p53 by recruiting hnRNPA2B1 in the nucleus. hnRNPA2B1 bound to N6-methyladenosine sites on the 3' untranslated region of p53 pre-mRNA and maintained its stability. Moreover, a lack of amino acids led to an elevated level of ROS, resulting in increased HIF1α, which promoted circMYH9 expression by binding to the promoter region. Furthermore, in vivo AAV9-mediated transfection of circMYH9 could drive chemically-induced carcinogenesis by suppressing p53 in mice. The overexpression of circMYH9 promotes CRC proliferation though modulating serine/glycine metabolism and redox homeostasis in a p53-dependent manner, and targeting circMYH9 and its pathway may be an effective strategy for the treatment of CRC.

中文翻译：

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CircMYH9 通过以 p53 依赖性方式调节丝氨酸代谢和氧化还原稳态来驱动结直肠癌的生长

环状 RNA (circRNA) 在癌症进展和代谢调节中发挥重要作用。丝氨酸/甘氨酸代谢通过促进它们的合成代谢需求和表观基因组以及通过调节它们的氧化还原状态来支持癌细胞的生长。然而，circRNA在调节丝氨酸/甘氨酸代谢中的作用尚未得到很好的阐明。微阵列分析用于筛选差异表达的新型circRNA。qRT-PCR和FISH用于分析circMYH9的表达。CCK8、集落形成和 FACS 用于分析结直肠癌 (CRC) 细胞的增殖。异种移植实验用于分析体内肿瘤生长。RNA测序、免疫印迹和LC-MS用于鉴定circMYH9的下游代谢途径。ChIRP，质谱，RIP 和 RNA pulldown 用于测试 circMYH9、hnRNPA2B1 和 p53 pre-mRNA 之间的相互作用。ChIP-qPCR 用于分析 HIF-1α 的结合位点。生成化学诱导的 CRC 小鼠以评估 circMYH9 在肿瘤发生中的作用。我们鉴定了一种内含子衍生的 circRNA，circMYH9，它在 CRC 组织中显着上调。较高的 circMYH9 水平与 CRC 患者较短的无复发生存期和总生存期相关。CircMYH9 促进丝氨酸/甘氨酸代谢、NAD + /NADH 比率和谷胱甘肽循环，并以 p53 依赖性方式抑制活性氧 (ROS)，影响肿瘤生长。从机制上讲，circMYH9 通过在细胞核中募集 hnRNPA2B1 使 p53 的前 mRNA 不稳定。hnRNPA2B1 与 3' 上的 N6-甲基腺苷位点结合 p53前mRNA的非翻译区并保持其稳定性。此外，氨基酸的缺乏会导致 ROS 水平升高，从而导致 HIF1α 增加，从而通过与启动子区域结合来促进 circMYH9 的表达。此外，体内 AAV9 介导的 circMYH9 转染可以通过抑制小鼠中的 p53 来驱动化学诱导的致癌作用。circMYH9的过表达通过以p53依赖性方式调节丝氨酸/甘氨酸代谢和氧化还原稳态来促进CRC增殖，靶向circMYH9及其通路可能是治疗CRC的有效策略。体内 AAV9 介导的 circMYH9 转染可通过抑制小鼠中的 p53 来驱动化学诱导的致癌作用。circMYH9的过表达通过以p53依赖性方式调节丝氨酸/甘氨酸代谢和氧化还原稳态来促进CRC增殖，靶向circMYH9及其通路可能是治疗CRC的有效策略。体内 AAV9 介导的 circMYH9 转染可通过抑制小鼠中的 p53 来驱动化学诱导的致癌作用。circMYH9的过表达通过以p53依赖性方式调节丝氨酸/甘氨酸代谢和氧化还原稳态来促进CRC增殖，靶向circMYH9及其通路可能是治疗CRC的有效策略。