ABSTRACT
Objective To investigate the effect of sodium arsenite (NaAsO2) on the expression of miRNA-21 (miR-21) mediated by transcription factor ETS-1 in human normal hepatocytes (L-02).Methods Dose-effect study:The L-02 cells were treated with different doses of NaAsO2 [0.0 (control),2.5,5.0,10.0,20.0,40.0 μmol/L] for 24 h.Time-effect study:L-02 cells were exposed to 0 (control) and 20 μmol/L NaAsO2 for 12,24,36 and 48 h (n =6).ETS-1 and miR-21 were treated with ETS-1 shRNA and miR-21 inhibitor,respectively.The cells treated with ETS-1 shRNA (100 nmol/L) were divided into 4 groups:①ETS-1 shRNA NC treatment alone (control group);②ETS-1 shRNA NC combined with NaAsO2 (20 μ,mol/L) treatment group;③ETS-1 shRNA treatment alone group;④Treatment with ETS-1 shRNA and NaAsO2 (20 μmol/L) group.The MiR-21 inhibitor (100 nmol/L) treated cells were also divided into 4 groups:① miR-21 inhibitor NC treatment (control group);② miR-21 inhibitor NC combined with NaAsO2 (20 μmol/L);③miR-21 inhibitor group;④miR-21 inhibitor combined with NaAsO2 (20 μ mol/L) treatment group.The expression of ETS-1 mRNA and miR-21 were detected by quantitative real-time PCR (qRT-PCR);the protein expression of ETS-1 was detected by Western blotting.Results Dose-effect study:The expression of ETS-1 mRNA in the groups of 0.0 (control),2.5,5.0,10.0,20.0 and 40.0 μmol/L was 1.008 ± 0.028,1.552 ± 0.029,1.697 ± 0.050,1.842 ± 0.077,2.233 ± 0.096 and 2.235 ± 0.092;miR-21 expression was 1.025 ± 0.094,1.552 ± 0.072,1.683 ± 0.066,1.915 ± 0.171,2.337 ± 0.195 and 2.592 ± 0.177;the expression of ETS-1 protein was 1.060 ± 0.045,1.267 ± 0.160,1.386 ± 0.087,1.723 ± 0.196,2.208 ± 0.122 and 2.284 ± 0.224,respectively,and the differences were statistically significant (F =47.797,8.959,65.748,all P ＜ 0.05),the NaAsO2 dose groups were significantly higher than those of the control group (all P ＜ 0.05),and there was a dose-effect relationship.Time-effect study:The expression of ETS-1 mRNA in L-02 cells was 1.253 ± 0.175,1.623 ± 0.220,1.771 ± 0.324 and 1.913 ± 0.251,respectively at 12,24,36 and 48 h;the expression of miR-21 was 1.502 ± 0.111,1.716 ± 0.113,1.979 ± 0.186 and 2.452 ± 0.304;the expression of ETS-1 protein was 1.196 ± 0.105,1.502 ± 0.076,1.651 ± 0.074 and 1.839 ± 0.139,respectively,there were significant differences between the groups (F =14.936,39.180,39.441,all P ＜ 0.05).The expression of various time points of exposure to NaAsO2 was significantly higher than those in the control group (1.044 ± 0.115,1.044 ± 0.124,1.108 ± 0.088,1.053 ± 0.061;1.092 ± 0.061,1.096 ± 0.169,1.024 ± 0.111,1.057 ± 0.146;1.020 ± 0.017,1.049 ± 0.121,1.024 ± 0.089,1.031 ± 0.124,all P＜ 0.05),and there was a time-effect relationship.ETS-1 shRNA and miR-21 inhibitor treatment:compared with ETS-1 shRNA NC combined with NaAsO2 (20 μmol/L),ETS-1 shRNA and NaAsO2 (20 μmol/L) could significantly inhibit the expression of ETS-1 (0.912 ± 0.238 vs 1.641 ± 0.225,P ＜ 0.05),and down-regulated the expression of miR-21 (1.313 ± 0.334 vs 2.363 ± 0.252,P ＜ 0.05).There was no significant difference of ETS-1 mRNA expression between miR-21 inhibitor and NaAsO2 (20.μmol/L) group (1.580 ± 0.077 vs 1.576 ± 0.065,P ＞ 0.05) compared with miR-21 inhibitor NC and NaAsO2 (20 μmol/L).Conclusions The expression of ETS-1 and miR-21 in L-02 cells is significantly higher than those in control.The high expression of ETS-1 mediates NaAsO2-induced miR-21 overexpression,which may be an important molecular mechanism of arsenic-induced expression dysregulation of human hepatic miRNAs and liver damage.