OBJECTIVETo investigate the effects of trichloroethylene (TCE) toxicity on the normal human liver cells (L02 cells) and hepatocytes with CYP2E1 gene overexpression which was constructed through molecular cloning technology in our laboratory, then to explore the roles of CYP2E1 gene in TCE toxicity.

METHODSL02 cells and hepatocytes with CYP2E1 overexpression were treated with various doses of TCE (0,0.25, 0.5, 1.0, 2.0, 4.0 mmol/L) for 12h, the expression of apoptosis genes (Bcl-2, Caspase-3, Caspase-8, Caspase-9) and oncogenes (c-fos, c-myc, k-ras, p53) were determined by real-time fluorescent PCR.

RESULTSBcl-2 mRNA expression levels increased significantly in normal liver cells and CYP2E1-overexpressing cells after TCE treatment, Bcl-2 levels were 20%∼50%higher in CYP2E1-overexpressing cells than in L02 liver cells at doses of 0.25∼2.0 mmol/L TCE. Caspase-3, Caspase-8 and caspase-9 mRNA expression increased by 30%∼600% in CYP2E1-overexpressing cells at doses of 0.5∼4.0 mmol/L TCE when compared with L02 cells (P < 0.01). Additionally, c-fos, k-ras and c-myc mRNA expression levels were 25%∼120% higher in CYP2E1-overexpressing cells than in L02 cells (P < 0.01), p53 mRNA expression levels were lower 10%∼50% in CYP2E1-overexpressing cells than in L02 cells (P < 0.05 or P < 0.01).

CONCLUSIONSThere were significant differences for apoptosis gene and oncogene expression levels between normal liver cells and CYP2E1-overexpressing cells after they were treated with TCE, these findings indicated that CYP2E1 might play an important role in TCE metabolism in vivo.