Background: Lung cancer is a common malignant tumor of the lung. To explore the molecular mechanism of the occurrence and development of lung cancer is a hot topic in current research. Cyclic RNA D1 (CircCCND1) is highly expressed in lung cancer and may be a potential target for the treatment of lung cancer. The aim of this study was to investigate the effect of CircCCND1 on the malignant biological behaviors of lung cancer cells by regulating the miR-340-5p/transforming growth factor β-induced factor homeobox 1 (TGIF1) axis.
Methods: The expression of CircCCND1, miR-340-5p, and TGIF1 mRNA in human normal lung epithelial cells BEAS-2B and human lung cancer H446 cells were detected. H446 cells cultured in vitro were randomly divided into control group, CircCCND1 siRNA group, miR-340-5p mimics group, negative control group, and CircCCND1 siRNA+miR-340-5p inhibitor group. Cell proliferation, mitochondrial membrane potential, apoptosis, migration, and invasion were detected, and the expressions of CircCCND1, miR-340-5p, TGIF1 mRNA, BCL2-associated X protein (Bax), cleaved Caspase-3, N-cadherin, E-cadherin, and TGIF1 proteins in each group were detected. The targeting relationship of miR-340-5p with CircCCND1 and TGIF1 was verified.
Results: Compared with BEAS-2B cells, CircCCND1 and TGIF1 mRNA were increased in H446 cells, and miR-340-5p expression was decreased (P<0.05). Knocking down CircCCND1 or up-regulating the expression of miR-340-5p inhibited the proliferation, migration and invasion of H446 cells, decreased the expression of TGIF1 mRNA and TGIF1 protein, and promoted cell apoptosis. Down-regulation of miR-340-5p could antagonize the inhibitory effect of CircCCND1 knockdown on the malignant biological behavior of H446 lung cancer cells. CircCCND1 may target the down-regulation of miR-340-5p, and miR-340-5p may target the down-regulation of TGIF1.
Conclusions: Knocking down CircCCND1 can inhibit the malignant behaviors of lung cancer H446 cells, which may be achieved through the regulation of miR-340-5p/TGIF1 axis.
【中文题目：CircCCND1调节miR-340-5p/TGIF1轴 对H446肺癌细胞恶性生物学行为的影响】 【中文摘要：背景与目的 肺癌是常见的肺部恶性肿瘤，探究肺癌发生发展的分子机制是当前研究的热点。环状RNA细胞周期蛋白D1（circular RNA Cyclin D1, CircCCND1）在肺癌中高表达，可能是治疗肺癌的潜在靶点。本研究旨在探讨CircCCND1调节miR-340-5p/转化生长因子β诱导因子同源框1（transforming growth factor β-induced factor homeobox 1, TGIF1）轴对肺癌细胞恶性生物学行为的影响。方法 检测人正常肺上皮细胞BEAS-2B及人肺癌H446细胞中CircCCND1、miR-340-5p及TGIF1 mRNA表达。将体外培养的H446细胞分为对照组、CircCCND1 siRNA组、miR-340-5p mimics组、阴性对照组、CircCCND1 siRNA+miR-340-5p inhibitor组，检测细胞增殖、线粒体膜电位、凋亡、迁移和侵袭情况，以及各组细胞CircCCND1、miR-340-5p、TGIF1 mRNA、BCL2相关X蛋白（BCL2-associated X protein, Bax）、剪切的半胱天冬氨酸蛋白酶3（cleaved Caspase-3）、N-钙黏蛋白（N-cadherin）、E-钙黏蛋白（E-cadherin）、TGIF1蛋白表达，并验证miR-340-5p与CircCCND1、TGIF1的靶向关系。结果 与BEAS-2B细胞相比，H446细胞CircCCND1、TGIF1 mRNA升高，miR-340-5p表达降低（P<0.05）。敲低CircCCND1或上调miR-340-5p表达可抑制H446细胞增殖、迁移、侵袭，降低TGIF1 mRNA和TGIF1蛋白表达，促进细胞凋亡；下调miR-340-5p可拮抗敲低CircCCND1对H446肺癌细胞恶性生物学行为的抑制作用。CircCCND1可能靶向下调miR-340-5p，miR-340-5p可能靶向下调TGIF1。结论 敲低CircCCND1可抑制肺癌H446细胞恶性行为，其作用可能是通过调控miR-340-5p/TGIF1轴实现的。 】 【中文关键词：CircCCND1；miR-340-5p/TGIF1；肺肿瘤；恶性生物学行为】.
Keywords: CircCCND1; Lung neoplasms; Malignant biological behavior; miR-340-5p/TGIF1.