Department of General Surgery, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, 362000, Fujian, China.
Department of Internal Medical Oncology, The 910th Hospital of the People's Liberation Army, Quanzhou, 362000, Fujian, China.
Biochem Biophys Res Commun. 2019 Sep 17;517(2):253-259. doi: 10.1016/j.bbrc.2019.07.065. Epub 2019 Jul 23.
Gastric cancer (GC) is a common malignant tumor, and many studies have shown that circular RNAs (circRNAs) play important roles in the progress of GC. This study showed that circ_SPECC1 was down-regulated in various GC cell lines, significantly inhibited GC cell proliferation and invasion, and promote apoptosis, which might play an anti-oncogene role. Circ_SPECC1 was mainly located in the cytoplasm, and its sequence contained multiple potential binding sites of miR-526b. Pull-down experiments with biotinylated miR-526b mimics and circ_SPECC1 probe showed that they could enrich each other. RIP experiments found hat anti-AGO2 antibody could significantly enrich circ_SPECC1. Further dual luciferase reporter gene assay also confirmed that miR-526b could bind directly to circ_SPECC1. miR-526b was also down-regulated in GC cells, and one of its important target genes was KDM4A. Both circ_SPECC1 and miR-526b inhibited the expression of KDM4A and its downstream effector YAP1, but miR-526b inhibitors terminated the above-mentioned inhibition of circ_SPECC1, and KDM4A overexpression reversed the inhibition of circ_SPECC1 and miR-526b on YAP1 expression. Both miR-526b and KDM4A siRNA inhibited GC cell proliferation and invasion, and promote apoptosis; KDM4A overexpression had the opposite effects, and significantly blocked the regulation of miR-526b on cell growth and invasion. Therefore, circ_SPECC1 can enhance miR-526b inhibitory effect on downstream KDM4A/YAP1 pathway by adsorbing it, thus inhibiting GC cell growth and invasion. These findings enrich the mechanism of circRNAs in GC and will provide more new targets for the prevention and treatment of GC.
胃癌（GC）是一种常见的恶性肿瘤，许多研究表明环状 RNA（circRNA）在 GC 的进展中发挥重要作用。本研究表明，circ_SPECC1 在各种 GC 细胞系中下调，显著抑制 GC 细胞增殖和侵袭，促进细胞凋亡，可能发挥抑癌基因的作用。circ_SPECC1 主要位于细胞质中，其序列包含多个 miR-526b 的潜在结合位点。用生物素标记的 miR-526b 模拟物和 circ_SPECC1 探针进行拉下实验表明，它们可以相互富集。RIP 实验发现，抗 AGO2 抗体可显著富集 circ_SPECC1。进一步的双荧光素酶报告基因检测也证实 miR-526b 可直接结合 circ_SPECC1。miR-526b 在 GC 细胞中也下调，其重要靶基因之一是 KDM4A。circ_SPECC1 和 miR-526b 均抑制 KDM4A 及其下游效应物 YAP1 的表达，但 miR-526b 抑制剂终止了 circ_SPECC1 上述抑制作用，而过表达 KDM4A 则逆转了 circ_SPECC1 和 miR-526b 对 YAP1 表达的抑制作用。miR-526b 和 KDM4A siRNA 均抑制 GC 细胞增殖和侵袭，促进细胞凋亡；而过表达 KDM4A 则具有相反的作用，显著阻断了 miR-526b 对细胞生长和侵袭的调节作用。因此，circ_SPECC1 可以通过吸附 miR-526b 来增强其对下游 KDM4A/YAP1 通路的抑制作用，从而抑制 GC 细胞的生长和侵袭。这些发现丰富了 circRNA 在 GC 中的作用机制，并为 GC 的预防和治疗提供了更多新的靶点。
