microRNA-142 is upregulated by tumor necrosis factor-alpha and triggers apoptosis in human gingival epithelial cells by repressing BACH2 expression

Tumor necrosis factor-alpha (TNF-alpha) has been shown to cause apoptosis of gingival epithelial cells (GECs) in periodontitis. However, the underlying molecular mechanism is still unclear. In this study, we showed that miR-142 expression was significantly elevated in human GECs after exposure to TNF-a. Such induction was in a time and concentration-dependent manner. Serum miR-142 levels were positively correlated with serum TNF-alpha levels in patients with chronic periodontitis (r = 0.314, P = 0.0152). Depletion of miR-142 was found to attenuate TNF-alpha-induced apoptosis, as determined by TUNEL staining and caspase-3 activity assays. In contrast, overexpression of miR-142 significantly reduced viability and induced apoptosis in GECs. Basic leucine zipper transcription factor 2 (BACH2) was identified to be a functional target of miR-142. Overexpression of miR-142 caused a 3-fold reduction of BACH2 protein in primary GECs. Overexpression of BACH2 significantly reversed miR-142-or TNF-alpha-induced apoptosis of GECs. Similar to the findings with miR-142 mimic, depletion of BACH2 significantly promoted apoptosis in GECs, which was accompanied by decreased expression of Bcl-2 and Bcl-xL and increased expression of Bax and Bim. Overall, miR-142 mediates TNF-alpha-induced apoptosis in gingival epithelial cells by targeting BACH2 and may represent a potential therapeutic target for periodontitis.