[Molecular mechanism of miR-369-3p regulating hepatocellular carcinoma cell proliferation and apoptosis by targeting ACTN4].

To investigate the effect of miR-369-3p targeting ACTN4 expression on proliferation and apoptosis of hepatocellular carcinoma cells. Real-time quantitative polymerase chain reaction (RT-qPCR) and western blot were used to detect the expression levels of miR-369-3p and ACTN4 in hepatocarcinoma tissues and adjacent tissues. MiR-369-3p mimics, miR-negative control (NC), si-ACTN4, and si-NC were transfected into hepatocellular carcinoma MHCC97H cells by liposome method. Cell proliferation was detected by 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-dipheny-ltetrazolium bromide (MTT) assay. Flow cytometry was used to detect cell cycle and apoptotic rates. The dual luciferase reporter assay was used to verify the targeted regulation of ACTN4 by miR-369-3p. Western blot was used to detect the expressions of cyclin D1, p21, Bcl-2 and Bax. The expression level of miR-369-3p in liver cancer tissue was lower than that in adjacent tissues [(0.46±0.04) vs (1.00±0.08), <0.001)], while the expression level of ACTN4 was higher than that in adjacent tissues [mRNA (3.12±0.29) vs (1.01±0.09); protein (0.61±0.06) vs (0.25±0.03), <0.001]. Overexpression of miR-369-3p significantly decreased the cell viability[(0.71±0.06) vs (1.26±0.11), <0.001)], increased cell apoptosis rate [(20.16±2.11)% vs (6.25±0.64)%, <0.001], increased the proportion of cells in G(1) phase [(31.14±3.36)% vs (51.56±5.23)%, <0.001], decreased the proportion of cells in S phase [(32.44±3.56)% vs (14.33) ±1.45)%, <0.001], increased the levels of p21 and Bax protein (<0.001), and decreased the levels of cyclin D1 and Bcl-2 protein (<0.001). Inhibition of the expression of ACTN4 significantly reduced the cell viability [(0.78±0.07) vs (1.24±0.12), <0.001], increased the apoptosis rate [(6.58±0.66)% vs (18.32±1.82)%, <0.001], increased the proportion of cells in G(1) phase [(48.69±4.21)% vs (30.33±3.01)%, <0.001], decreased the proportion of cells in S phase [(36.21±3.42)% vs (18.54±1.61)%, <0.001], increased the protein levels of p21 and Bax (<0.001), and decreased the levels of cyclin D1 and Bcl-2 protein (<0.001). Compared with the miR-369-3p+ pcDNA group, overexpression of ACTN4 increased the proliferation ability of hepatocellular carcinoma MHCC97H cells at 72 hours of culture[(1.12±0.11) vs (0.68±0.06), <0.001], significantly reduced the proportion of cells in G(1) stage [(38.81±3.24)% vs (51.80±4.57)%, <0.001], significantly increased the proportion of S-phase cells [(31.65±3.11)% vs (15.69±1.44)%, <0.001], decreased cell apoptosis rate [(13.86±1.37)% vs (22.69±2.24)%, <0.001], increased protein expressions of cyclin D1 and Bcl-2 (<0.001), decreased the protein expressions of p21 and Bax (<0.001). MiR-369-3p can induce cell cycle arrest in G(1) phase, inhibit the proliferation and promote apoptosis of liver cancer cells by regulating the expression of ACTN4.