As one of the deadliest malignancies, gastric cancer (GC) is often accompanied by a low 5-year survival following initial diagnosis, which accounts for a substantial proportion of cancer-related deaths each year worldwide. Altered epigenetic modifications of cancer oncogenes and tumor suppressor genes emerge as novel mechanisms have been implicated the pathogenesis of GC. In the current study, we aim to elucidate whether histone deacetylase 3 (HDAC3) exerts oncogenic role in GC, and investigate the possible mechanism. Initially, we collected 64 paired cancerous and noncancerous tissues surgically resected from GC patients. Positive expression of HDAC3, FTO, and MYC in the tissues was measured using Immunohistochemistry. Meanwhile, GC cell line BGC-823/AGS was selected and treated with lentivirus vectors for alteration of HDAC3, FTO, or FOXA2 expressions, followed by detection on mRNA and protein levels of HDAC3, FOXA2, FTO, and MYC using reverse transcription quantitative polymerase chain reaction (RT-qPCR) and western blot assays. The results demonstrated that the expressions of HDAC3, FTO and MYC were upregulated, while FOXA2 expression was downregulated in GC tissues and cells. After that, the cell viability, migration, and invasion of GC cells were assessed by CCK-8 and Transwell assays, revealing that HDAC3 accelerated GC cell viability, migration and invasion by degrading FOXA2. Subsequently, the binding relationship among HDAC3, FOXA2, FTO, and MYC was assessed by assays of immunoprecipitation, dual-luciferase reporter gene, and chromatin immunoprecipitation assay. Methylation of m6A mRNA in GC cells was detected via gene-specific m6A qPCR and dot-blot assays. The transcription factor FOXA2 was found to bind to the FTO gene promoter and decreased its expression, while FTO stabilized MYC mRNA by reducing m6A methylation of MYC in GC cells. In addition, HDAC3 was observed to maintain the FTO/m6A/MYC signaling and regulated GC progression, which was also supported by in vivo animal study data of GC cell tumorigenesis in nude mice. These key observations uncover the tumor-initiating activities of HDAC3 in GC through its regulation on FOXA2-mediated FTO/m6A/MYC axis, highlighting the potential of therapeutically targeting epigenetic modifications to combat GC.

作为最致命的恶性肿瘤之一，胃癌 (GC) 在初始诊断后通常伴随着较低的 5 年生存率，这在全世界每年与癌症相关的死亡中占很大比例。癌症致癌基因和抑癌基因的表观遗传修饰发生改变，因为新机制与 GC 的发病机制有关。在目前的研究中，我们旨在阐明组蛋白去乙酰化酶 3 (HDAC3) 是否在 GC 中发挥致癌作用，并研究可能的机制。最初，我们收集了从 GC 患者手术切除的 64 对癌性和非癌性组织。使用免疫组织化学测量组织中 HDAC3、FTO 和 MYC 的阳性表达。同时，选择GC细胞系BGC-823/AGS并用慢病毒载体处理以改变HDAC3、FTO、或 FOXA2 表达，然后使用逆转录定量聚合酶链反应 (RT-qPCR) 和蛋白质印迹分析检测 HDAC3、FOXA2、FTO 和 MYC 的 mRNA 和蛋白质水平。结果表明HDAC3、FTO和MYC的表达上调，而FOXA2在GC组织和细胞中的表达下调。之后，通过CCK-8和Transwell测定评估GC细胞的细胞活力、迁移和侵袭，揭示HDAC3通过降解FOXA2加速GC细胞活力、迁移和侵袭。随后，通过免疫沉淀法、双荧光素酶报告基因和染色质免疫沉淀法评估了 HDAC3、FOXA2、FTO 和 MYC 之间的结合关系。通过基因特异性 m6A qPCR 和斑点印迹分析检测到 GC 细胞中 m6A mRNA 的甲基化。发现转录因子 FOXA2 与 FTO 基因启动子结合并降低其表达，而 FTO 通过降低 GC 细胞中 MYC 的 m6A 甲基化来稳定 MYC mRNA。此外，观察到 HDAC3 维持 FTO/m6A/MYC 信号传导并调节 GC 进展，这也得到了裸鼠 GC 细胞肿瘤发生的体内动物研究数据的支持。这些关键观察结果揭示了 HDAC3 在 GC 中的肿瘤起始活性，通过其对 FOXA2 介导的 FTO/m6A/MYC 轴的调节，突出了治疗靶向表观遗传修饰以对抗 GC 的潜力。观察到 HDAC3 维持 FTO/m6A/MYC 信号传导并调节 GC 进展，这也得到了裸鼠 GC 细胞肿瘤发生的体内动物研究数据的支持。这些关键观察结果揭示了 HDAC3 在 GC 中的肿瘤起始活性，通过其对 FOXA2 介导的 FTO/m6A/MYC 轴的调节，突出了治疗靶向表观遗传修饰以对抗 GC 的潜力。观察到 HDAC3 维持 FTO/m6A/MYC 信号传导并调节 GC 进展，这也得到了裸鼠 GC 细胞肿瘤发生的体内动物研究数据的支持。这些关键观察结果揭示了 HDAC3 在 GC 中的肿瘤起始活性，通过其对 FOXA2 介导的 FTO/m6A/MYC 轴的调节，突出了治疗靶向表观遗传修饰以对抗 GC 的潜力。