Abstract: Objective To investigate the effect of tamoxifen（TAM） on steatosis in HepG2 cells in vitro and on the expression of key regulators involved in lipid metabolism in the cells. Methods A cell model of steatosis was induced in HepG2 cells in vitro with oleic acid（OA） at 50 μmol/L;HepG2 cells were then subjected to different concentrations of TAM（5 to 20 μmol/L） at the presence of OA for 72 h;Intracellular lipid accumulation was assessed by oil red O staining and measurement of triglyceride;The expression of sterol regulatory element-binding protein-1c（SREBP-1c）,fatty acid synthase（FAS）,steroyl-CoA desaturase（SCD）,carnitine palmitoyltransferase 1（CPT1）and mitochondrial trifunctional protein（MTP）was determined by Western blot;Cell viability was detected by cell counting Kit-8 assay. Results After incubation for 72 h,the intracellular triglyceride in control group was（16.53±0.17） mg/100 mg protein,similar to that of cells treated with 5μmol/L TAM,however,the intracellular triglyceride was increased by 31%[（21.57±0.16） mg/100 mg protein] and 44%[（23.82±0.44） mg/100 mg protein] in cells treated with 10 μmol/L and 20 μmol/L of TAM,respectively（P<0.05）;TAM treatment（5 to 10 μmol/L）significantly increased the expression of SREBP-1c,FAS,SCD and MTP without affecting the expression of carnitine palmitoyltransferase 1（CPT1） in HepG2 cells;TAM did not affect HepG2 viability. Conclusions TAM promotes OA-induced cell steatosis,probably by up-regulation of SREBP-1c,FAS and SCD,thus increases fatty acid synthesis in the cells.

Key words: HepG 2 cells, Tamoxifen, Steatosis, Triglyceride, Fatty acid synthesis