Targeting circular RNA has been a novel approach to preventing and limiting acute myocardial infarction (AMI). Here, we planned to investigate the role and mechanism of circ_0020887 in AMI progression.

Hypoxic injury in human cardiomyocytes (AC16) was measured using cell counting kit-8 assay, 5-ethynyl-2′-deoxyuridine assay, flow cytometry, and colorimetric assay kits. RNA and protein expressions were determined using real-time quantitative PCR and western blotting. Direct interplay between RNAs was determined using dual-luciferase reporter, RNA pull-down, and RIP assays.

In the plasma and hypoxia-induced AC16 cells of patients with AMI, circ_0020887 and miR-370-3p were upregulated and downregulated, respectively, concomitant with the upregulation of cytochrome P450 1B1 (CYP1B1). Circ_0020887 interference could inhibit hypoxia-induced AC16 cell apoptosis, oxidative stress, and inflammatory response. Circ_0020887 could sponge miR-370-3p, and miR-370-3p could target CYP1B1. The inhibition effect of circ_0020887 knockdown on hypoxia-induced AC16 cell injury could be reversed by the miR-370-3p inhibitor. Besides, CYP1B1 overexpression also overturned the suppressive effect of miR-370-3p on hypoxia-induced AC16 cell apoptosis, oxidative stress, and inflammatory response.

In conclusion, circ_0020887 regulated the miR-370-3p/CYP1B1 axis to regulate hypoxia-induced cardiomyocyte injury, confirming that circ_0020887 might promote cardiomyocyte injury.

靶向环状 RNA 已成为预防和限制急性心肌梗死 (AMI) 的一种新方法。在这里，我们计划研究circ_0020887在AMI进展中的作用和机制。

使用细胞计数试剂盒 8 测定、5-乙炔基-2'-脱氧尿苷测定、流式细胞术和比色测定试剂盒测量人心肌细胞 (AC16) 的缺氧损伤。使用实时定量 PCR 和蛋白质印迹法测定 RNA 和蛋白质表达。 RNA 之间的直接相互作用通过双荧光素酶报告基因、RNA pull-down 和 RIP 测定来确定。

在 AMI 患者的血浆和缺氧诱导的 AC16 细胞中，circ_0020887 和 miR-370-3p 分别上调和下调，同时细胞色素 P450 1B1 (CYP1B1) 上调。 Circ_0020887干扰可以抑制缺氧诱导的AC16细胞凋亡、氧化应激和炎症反应。 Circ_0020887可以海绵miR-370-3p，而miR-370-3p可以靶向CYP1B1。 circ_0020887 敲低对缺氧诱导的 AC16 细胞损伤的抑制作用可以被 miR-370-3p 抑制剂逆转。此外，CYP1B1过表达还推翻了miR-370-3p对缺氧诱导的AC16细胞凋亡、氧化应激和炎症反应的抑制作用。

总之，circ_0020887通过调节miR-370-3p/CYP1B1轴来调节缺氧诱导的心肌细胞损伤，证实circ_0020887可能促进心肌细胞损伤。