microRNA-125b acts as a tumor suppressor by targeting signal transduction activator 3 in proliferation and invasion of cutaneous squamous cell carcinoma

Objective To investigate the expression of microRNA-125b (miR-125b) and signal transduction activator 3 (STAT3) in cutaneous squamous cell carcinoma (CSCC), and to explore the molecular mechanism of miR-125b targeting STAT3 to regulate the occurrence and development of CSCC. Methods qRT-PCR and Western blot were used to detect the expression of microRNA-125b and STAT3 in 32 cases of CSCC tissues and adjacent normal skin tissues, as well as in CSCC cell lines (A431, SCC13 and SCL-1) and normal skin cell lines HaCaT. Luciferase reporter gene experiment was used to verify that miR-125b targets STAT3. tetrazolium-based colorimetric assay (MTT) and flow cytometry were used to detect the effects of microRNA-125b mimic or STAT3 shRNA on cell proliferation, cell cycle and apoptosis of CSCC cell lines (A431, SCC13 and SCL-1). The effects of microRNA-125b mimic on the proliferation, metastasis and invasion of CSCC cell line A431 were observed by colony formation and Transwell assay. Results Compared with normal skin tissues and cells, the expression of miR-125b in CSCC tissues and cells decreased significantly, while the expression of STAT3 increased significantly. miR-125b targets 3 ′- UTR of STAT3 to regulate its expression. After miR-125b mimic or STAT3 shRNA transfection, the proliferation and cell cycle of A431, SCC13 and SCL-1 cells was significantly inhibited, while the proportion of cells in G0/G1 phase was significantly increased, and cell apoptosis was promoted. Moreover, miR-125b mimic could significantly inhibit the ability of colony formation, cell migration and invasion in A431 cells. Conclusion The abnormal expression of miR-125b / STAT3 contributes to the development and progression of CSCC by influencing cell proliferation, apoptosis and invasion. Both of them can be used as new diagnostic and therapeutic targets for CSCC. 摘要：目的 观察 microRNA-125b (miR-125b) 和信号传导转录激活因子 3 (STAT3) 在皮肤鳞状细胞癌 (CSCC) 中的 表达, 并探讨 miR-125b 靶向 STAT3 进而调控 CSCC 发生发展的分子机制。 方法 采用 qRT-PCR 法和 Western Blot 检测 32 例 CSCC 组织及其周围正常皮肤组织中以及 CSCC 细胞系 (A431、SCC13 和 SCL-1) 和正常皮肤细胞系 HaCaT 中 miR-125b 和 STAT3 的表达。荧光素酶报告基因实验被用于验证 miR-125b 对 STAT3 的靶向作用。采用 MTT 法和流式细胞 术检测 miR-125b mimic 或 STAT3 shRNA 对 CSCC 细胞系 (A431、SCC13 和 SCL-1) 细胞增殖、细胞周期和细胞凋亡的影 响。采用克隆形成实验、细胞转移和侵袭实验观察 miR-125b mimic 对 CSCC 细胞系 A431 细胞的增殖、转移和侵袭能力 的影响。 结果 与正常皮肤组织和细胞相比, CSCC 组织和细胞中 miR-125b 表达显著下降, 而 STAT3 的表达则显著上 调。miR-125b 靶向 STAT3 的 3 ′-UTR 发挥对其表达的调控作用。miR-125b mimic 或 STAT3 shRNA 转染后, A431、SCC13 和 SCL-1 细胞的增殖明显受抑制, G0/G1 期细胞比例明显增加, 并且促进了细胞凋亡。miR-125b mimic 能明显 抑制 A431 细胞的克隆形成、细胞转移和侵袭的能力。 结论 miR-125b/STAT3 的表达异常通过影响细胞的增殖、凋亡 和侵袭参与了 CSCC 的发生发展。二者可成为 CSCC 新的诊断和治疗靶点。