Abstract: OBJECTIVE: To investigate whether formaldehyde can induce endoplasmic reticulum stress in hepatocytes. METHODS: Hoechst 33258 was used for nuclear staining to observe morphological changes of hepatocytes in different formaldehyde concentration groups. The human hepatocellular carcinoma cell line HepG2 was treated with formaldehyde (FA) solution at 0.004 mmol/L,0.02 mmol/L and 0.1 mmol/L for 24 h and 48 h respectively. Expression of Bip and CANX mRNA in stress-related genes was detected by fluorescence quantitative PCR (qPCR). Western blot was used to detect the expression of stress-related immunoglobulin heavy chain binding protein (Bip) and connexin (CANX) in endoplasmic reticulum. RESULTS: Cells in the negative control group and the low dose group were significantly higher with Hoechst 33258 staining than in the control group (P < 0.05). Results of qPCR show that expression of Bip and CANX mRNA in each dose group was not significantly different from that in the negative control group. Results of Western blot show that there was no significant difference in the expression of Bip and CANX proteins among the different doses of FA group and the negative control group (P>0.05). Compared with the negative control group (P < 0.05), expression of Bip protein was increased in 0.02 mmol/L and 0.1 mmol/L FA group,the difference was statistically significant (P < 0.05). CONCLUSION: Formaldehyde exposure may induce endoplasmic reticulum stress of hepatocytes.

Key words: formaldehyde, endoplasmic reticulum stress, hepatocytes, Bip, CANX