胃癌（GC）是一种严重威胁人类健康的恶性癌症。尽管在治疗方面有所发展，但晚期GC患者的预后仍然较差。因此，详细阐明分子机制和潜在治疗靶点对于GC研究非常重要。近年来，环状RNA已被广泛报道为癌症发生和进展中的重要调节因子。本研究旨在评估circRHOT1在GC发展中的功能。从GC患者收集临床样本以检测circRHOT1的水平。通过定量实时聚合酶链式反应检测几种GC细胞系中circRHOT1的表达。使用细胞计数试剂盒8（CCK-8）、集落形成和异种移植瘤生长实验来检测细胞增殖。通过细胞内铁、Fe2+（二价铁离子）、脂质活性氧、丙二醛和谷胱甘肽的水平来确定细胞铁死亡。通过免疫印迹实验检测SLC7A11和谷胱甘肽过氧化物酶-4（GPX4）的蛋白水平。通过染色质免疫沉淀实验分析GPX4基因的表观遗传调控。circRHOT1在GC肿瘤中的表达水平较相邻非肿瘤组织高。circRHOT1的沉默显著抑制了细胞生长（P <0.05），并促进了GC细胞的铁死亡（P <0.05）。circRHOT1招募KAT5（乙酰转移酶Tip60）来促进GPX4基因上组蛋白H3亚单位（H3k27Ac）的赖氨酸27位点的乙酰化并刺激基因转录。KAT5和GPX4的过表达明显逆转了circRHOT1减少的抗增殖效应（P <0.05）。circRHOT1通过招募KAT5启动GPX4转录促进了GC进展并抑制了铁死亡。我们的发现表明，cirRHOT1是GC治疗的一个有前景的靶点。2023年《胃肠肿瘤学杂志》。保留所有权利。

Gastric cancer (GC) is a malignant form of cancer that severely threatens human health. Despite developments on treatment, the prognosis of patients with advanced GC remains poor. Hence, the identification of detailed molecular mechanisms and potential therapeutic targets is of great importance for GC study. In recent years, circular RNAs have been widely reported to be important regulators in cancer initiation and progression. This study sought to evaluate the function of circRHOT1 in GC development.Clinical specimens were collected from patients with GC to detect the level of circRHOT1. The expression of circRHOT1 in several GC cell lines was detected by quantitative real-time polymerase chain reaction. Cell Counting Kit 8 (CCK-8), colony formation, and xenograft tumor growth experiments were performed to check cell proliferation. Cell ferroptosis was determined by the levels of intracellular iron, Fe2+ (Divalent iron ion), lipid reactive oxygen species, malondialdehyde, and glutathione. The protein levels of SLC7A11 and glutathione peroxidase-4 (GPX4) were detected by western blot assays. The epigenetic regulation of the GPX4 gene was analyzed by chromatin immunoprecipitation assays.CircRHOT1 was more highly expressed in the GC tumors than the adjacent non-tumor tissues. The knockdown of circRHOT1 significantly suppressed cell growth (P<0.05) and stimulated the ferroptosis of the GC cells (P<0.05). CircRHOT1 recruited KAT5 (Acetyltransferase Tip60) to promote the acetylation of lysine 27 on histone H3 protein subunit (H3k27Ac) of the GPX4 gene and stimulated gene transcription. The overexpression of KAT5 and GPX4 notably reversed the anti-proliferation effect of circRHOT1 depletion (P<0.05).CircRHOT1 promoted GC progression and suppressed ferroptosis by recruiting KAT5 to initiate GPX4 transcription. Our findings showed that cirRHOT1 is a promising target for GC treatment.2023 Journal of Gastrointestinal Oncology. All rights reserved.