Effects of vinyl chloride monomer on cell cycle and expression of mir-21 and mir-192 in liver of rat

Objective To explore the sub-chronic toxicity effects of vinyl chloride monomer (VCM) on cell cycle and the expression of cell cycle related microRNA 21(mir-21)and microRNA 192 (mir-192) of rat liver. Methods Thirty-two healthy sprague dawley (SD) rats were randomly divided into three VCM exposure groups (5 mg/kg, 25 mg/kg and 125 mg/kg) and a control group (25 mg/kg clean air). The rats were exposed by intraperitoneal injection three times a week (every other day) for three months. The flow cytometry was used to measure the percent of each phase(G0/G1, S, and G2/M). The mir-21 and mir-192 was extracted and then quantified using real-time fluorescent quantitative PCR. Results The percentage of each phase of cell cycle was not significantly different among four groups (all P>0.05). The proportion of S-phase cells in 125 mg/kg group was higher than the control group(t=-4.363,P=0.024). Besides, the expressions of mir-21 varied significantly among four groups (H=16.064, P=0.001) and, furthermore, decreased significantly in both 25 mg/kg and 125 mg/kg group when they were compared with control and 5 mg/kg group (all P<0.05). Meanwhile, the expressions of mir-192 also varied significantly (H=15.939, P=0.001), and decreased significantly in both 25 mg/kg and 125 mg/kg group, compared with control and 5 mg/kg group (all P<0.05). Conclusions VCM sub-chronic exposure induced the increase of S-phase cells and decrease of the expression of mir-21 and mir-192.