miR­29b suppresses proliferation and induces apoptosis of hepatocellular carcinoma ascites H22 cells via regulating TGF­ß1 and p53 signaling pathway.

MicroRNA (miR)­29b is a key tumor regulator. It can inhibit tumor cell proliferation, induce apoptosis, suppress tumor invasion and migration, thus delaying tumor progression. Our previous studies revealed an increased level of miR­29b in hepatoma 22 (H22) cells in ascites tumor­bearing mice. The present study investigated the effect of miR­29b on proliferation and apoptosis of hepatocellular carcinoma ascites H22 cells and its association with the transforming growth factor­ß1 (TGF­ß1) signaling pathway and p53­mediated apoptotic pathway. Briefly, H22 cells were transfected with miR­29b­3p (hereinafter referred to as miR­29b) mimic or miR­29b inhibitor. MTS cell proliferation assay and flow cytometry were used to analyze cell viability and apoptosis. The expression change of the TGF­ß1 signaling pathway and p53­mediated apoptotic pathway were detected by reverse transcription­quantitative PCR, western blotting and immunofluorescence. Furthermore, cells were treated with exogenous TGF­ß1 and TGF­ß1 small interfering RNA to evaluate the crosstalk between TGF­ß1 and p53 under miR­29b regulation. The overexpression of miR­29b decreased cell viability, increased cell apoptosis, activated the TGF­ß1 signaling pathway and p53­mediated apoptotic pathway. Conversely, these effects were reversed by the miR­29b inhibitor. Moreover, the effect of miR­29b mimic was further increased after treating cells with exogenous TGF­ß1. The activation of the TGF­ß1 signaling pathway and p53­mediated apoptotic pathway induced by miR­29b overexpression were reversed by TGF­ß1 inhibition. In summary, these data indicated that miR­29b has an important role in proliferation and apoptosis of H22 cells by regulating the TGF­ß1 signaling pathway, the p53­dependent apoptotic pathway, and the crosstalk between TGF­ß1 and p53.