The consumption of nicotine via smoking tobacco has been reported to stimulate the occurrence and progression of periodontitis. Many studies have demonstrated that nicotine prevents the regeneration of periodontal tissues primarily by inhibiting the proliferation of human periodontal ligament (PDL) cells. However, the mechanisms underlying this process are still unclear. Therefore, we investigated whether nicotine-upregulated miR-30a inhibited the proliferation of human PDL cells by downregulating cyclin E2 (CCNE2), in vitro. Quantitative real-time PCR analysis revealed that nicotine upregulated the expression of miR-30a in human PDL cells. In addition, nicotine inhibited the proliferation of human PDL cells by inducing cell cycle arrest. To support this hypothesis, we showed that nicotine downregulated the expression of CCNE2 in human PDL cells, whereas inhibition of miR-30a restored CCNE2 expression that had been downregulated by nicotine. Furthermore, using luciferase reporter assays, we found that miR-30a directly interacts with the CCNE2 3'UTR. In conclusion, these findings indicate that nicotine-upregulated miR-30a inhibits the proliferation of human PDL cells by downregulating the expression of CCNE2.

中文翻译：

---

尼古丁上调的 miR-30a 通过直接靶向人牙周膜细胞中的 CCNE2 使细胞周期停滞在 G1 期。

据报道，通过吸烟摄入尼古丁会刺激牙周炎的发生和发展。许多研究表明，尼古丁主要通过抑制人牙周膜（PDL）细胞的增殖来阻止牙周组织的再生。然而，这一过程背后的机制仍不清楚。因此，我们在体外研究了尼古丁上调的 miR-30a 是否通过下调细胞周期蛋白 E2 (CCNE2) 来抑制人 PDL 细胞的增殖。定量实时 PCR 分析显示，尼古丁上调了人 PDL 细胞中 miR-30a 的表达。此外，尼古丁通过诱导细胞周期停滞来抑制人类 PDL 细胞的增殖。为了支持这一假设，我们发现尼古丁下调了人 PDL 细胞中 CCNE2 的表达，而抑制 miR-30a 恢复了已被尼古丁下调的 CCNE2 表达。此外，使用荧光素酶报告基因检测，我们发现 miR-30a 直接与 CCNE2 3'UTR 相互作用。总之，这些发现表明尼古丁上调的 miR-30a 通过下调 CCNE2 的表达来抑制人 PDL 细胞的增殖。