OBJECTIVETo investigate the effects of hydroquinone (HQ) on expression of ubiquitin-ligating enzyme Rad18 in human hepatic cells (L-02), and to explore the role and possible mechanism of Rad18 involved in toxicity of HQ to hepatic cells.

METHODSAfter L-02 hepatic cells were exposed to HQ with various concentrations (0, 5, 10, 20, 40, 80 and 160 micromol/L) for 24 h, cell survival rate was measured by MTT assay; DNA impairment was evaluated by single cell gel electrophoresis (SCGE); The expression levels of Rad18 mRNA and protein were detected by Real-time fluorescent quantitative polymerase chain reaction (QPCR) technique and Western blot method respectively.

RESULTSHQ with concentration from 0 to 80 micromol/L had little effect on survival rate of L-02 (P > 0.05); Whereas the survival rate in the group of 160 micromol/L was significantly lower than in the control with the significant difference (P < 0.01) after treated with HQ for 24 h; The higher dose of HQ presented, the more degrees of olive tail moment (OTM) were produced and a dose-dependent relationship was shown. HQ in a low concentration (0 to approximately 40 micromol/L) could induce increase in the expression of Rad18 mRNA and protein which was in proportion to the increment of HQ concentration; the expression of Rad18 mRNA was enhanced increasingly, while the expression of Rad18 protein unchanged basically once the concentration of HQ exceeded 40 micromol/L; Besides, there was a positive correlation between OTM and the expression level of Rad18 mRNA (r = 0.919, P < 0.01).

CONCLUSIONHQ could regulate up the expression of Rad18 in L-02 hepatic cells.