DNA methyltransferase inhibitor suppresses fibrogenetic changes in human conjunctival fibroblasts

PURPOSE: This study aimed to clarify the effects of a DNA methyltransferase inhibitor on fibrogenetic changes in human conjunctival fibroblasts (HConF). METHODS: HConF were pretreated with the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine (5-Aza-dC) for 48 h. After one passage, the cells were treated with 5 ng/ml of transforming growth factor (TGF)-β2 for 48 h, and the expression levels of α-smooth muscle actin (α-SMA), extracellular matrix proteins, and phosphorylated Smad3 were evaluated with western blotting. A fusion construct between the COL1A2 promoter and the luciferase gene was introduced into the HConF after the first passage, and the construct’s activity was detected via a luciferase reporter gene assay. RESULTS: TGF-β2-induced upregulation of α-SMA was suppressed by pretreatment with 5-Aza-dC (0.1, 1.0, and 10 μM) in a dose-dependent manner. Upregulation of type I collagen was also suppressed by 10 μM 5-Aza-dC pretreatment. In contrast, 5-Aza-dC had no inhibitory effect on the expression of fibronectin or phosphorylated Smad3. However, COL1A2 promoter activity was suppressed with 5-Aza-dC pretreatment. CONCLUSIONS: In HConF, fibrogenetic changes were partly suppressed with a DNA methyltransferase inhibitor, suggesting an indirect inhibitory effect of the inhibitor on the COL1A2 promoter in HConF.