Abstract: OBJECTIVE:To explore effects of formaldehyde (FA) on intra-hepatocellular free cholesterol content in HepG2 cells. METHODS:HepG2 cells were treated with formaldehyde at 0.004,0.02 and 0.1 mmol/L concentrations for 24 and 48 hours,respectively. The content of intra-hepatocellular free cholesterol was detected by using free the cholesterol GPO-POD assay kit. Western blot was used to detect protein expression of the sterol regulatory element-binding protein (SREBP) -2,hydroxy mothylglutaryl coenzyme A reductase (HMGCR),acyl coenzyme A-cholesterol acyltransferase (ACAT) and low-density lipoprotein receptor (LDLR). RESULTS:Compared with negative control,the contents of intra-hepatocellular FC were increased significantly after treatments with FA for 24 h and 0.02 and 0.1 mmol/L for 48 h (P < 0.05). HMGCR expression levels were significantly increased after exposure to formaldehyde for 24 and 48 h (P < 0.05). After treatment with FA for 24 h,expression levels of ACAT and LDLR were significantly down-regulated (P < 0.05). After 48 h,expression levels of LDLR were decreased significantly,whereas the levels of ACAT were decreased significantly after treatment with 0.02 and 0.1 mmol/L FA (P < 0.05). CONCLUSION:FA exposure increased intra-hepatocellular free cholesterol contents in HepG2 cells. The increase could be caused by elevated de novo synthesis of cholesterol and decreased cholesterol esterification.

Key words: formaldehyde, sterol regulatory element binding protein 2, hydroxy mothylglutaryl coenzyme A reductase, acyl coenzyme A-cholesterol acyltransferase, low-density lipoprotein receptor