Abstract Context Oral submucous fibrosis (OSF) is a chronic and progressive disease. Arecoline, present in betel nuts, has been proposed as a vital aetiological factor. However, the underlying mechanism remains unclear. Objectives This research elucidates the expression of tropomyosin-1 (TPM1) and its regulation mechanism in HaCaT cells treated with arecoline. Materials and methods HaCaT cells were assigned into three groups: (1) Control; (2) Treated with arecoline (0.16 mM) for 48 h (3) Treated with arecoline (0.16 mM) and transfected with small interfering RNA (siRNA) for TPM1 (50 nM) for 48 h. CCK8, cell cycle, and apoptosis phenotypic analyses were performed. PCR and western blot analyses were performed to detect the expression level of TPM1 and examine the related signalling pathway. Results The IC50 of arecoline was approximately 50 μg/mL (0.21 mM). The arecoline dose (0.16 mM) and time (48 h) markedly increased TPM1 expression at the mRNA and protein levels in HaCaT cells. Arecoline suppressed the cell growth, caused cell cycle arrest at the G1 phase, and induced cell apoptosis in HaCaT cells. siRNA-mediated knockdown of TPM1 attenuated the effect of arecoline on cell proliferation, apoptosis, and cell cycle arrest at the G1 phase. Furthermore, blocking of the transforming growth factor (TGF)-β receptor using SB431542 significantly suppressed TPM1 expression in the cells treated with arecoline. Discussion and conclusions Arecoline suppresses HaCaT cell viability by upregulating TPM1 through the TGF-β/Smad signalling pathway. This research provides a scientific basis for further study of arecoline and TPM1 in OSF and can be generalised to broader pharmacological studies. TPM1 may be a promising molecular target for treating OSF.

中文翻译：

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槟榔碱通过转化生长因子-β/Smad 通路上调原肌球蛋白-1 抑制上皮细胞活力

摘要 背景口腔黏膜下纤维化（OSF）是一种慢性进行性疾病。槟榔中存在的槟榔碱已被认为是一种重要的病因。然而，潜在的机制仍不清楚。目的 本研究阐明槟榔碱处理 HaCaT 细胞中原肌球蛋白 1 (TPM1) 的表达及其调控机制。材料和方法 HaCaT 细胞分为三组：（1）对照；(2) 用槟榔碱 (0.16 mM) 处理 48 小时 (3) 用槟榔碱 (0.16 mM) 处理并用 TPM1 (50 nM) 的小干扰 RNA (siRNA) 转染 48 小时。进行CCK8、细胞周期和细胞凋亡表型分析。进行 PCR 和蛋白质印迹分析以检测 TPM1 的表达水平并检查相关的信号通路。结果槟榔碱的IC50约为50 μg/mL (0. 21 毫米）。槟榔碱剂量 (0.16 mM) 和时间 (48 h) 显着增加了 HaCaT 细胞中 mRNA 和蛋白质水平的 TPM1 表达。Arecoline 抑制细胞生长，导致细胞周期停滞在 G1 期，并诱导 HaCaT 细胞中的细胞凋亡。siRNA 介导的 TPM1 敲低减弱了槟榔碱对 G1 期细胞增殖、凋亡和细胞周期停滞的影响。此外，使用 SB431542 阻断转化生长因子 (TGF)-β 受体可显着抑制用槟榔碱处理的细胞中 TPM1 的表达。讨论和结论 Arecoline 通过 TGF-β/Smad 信号通路上调 TPM1 抑制 HaCaT 细胞活力。该研究为进一步研究OSF中槟榔碱和TPM1提供了科学依据，并可推广到更广泛的药理学研究。