The pathological role of endoplasmic reticulum stress in fluorosis-induced apoptosis of human hepatocellular cardnoma cell line (HepG2)

Abstract

Objective To investigate the pathological role of endoplasmic reticulum stress in fluorosisinduced apoptosis in human hepatocellular carcinoma cell line (HepG2). Methods Under stimulation of 1, 3, 6, 9 mmol/L concentrations of NaF in vitro for 24 h, while normal control group was cultured under normal condition, the apoptosis of HepG2 cells was measured by flow cytometry. The endoplasmic reticulum stress markers(glucose regulative proteins 78, 94; GRP78, GRP94) and CCAAT/enhancer-binding protein homologous protein(CHOP) in HepG2 cells were measured at both mRNA and protein levels by real-time PCR and Western blotting, respectively. Results After treated with 0, 1, 3, 6, 9 mmol/L NaF for 24 h, the apoptosis rate of HepG2 cells was (6.25±1.27)%, (13.48±1.00)%, (24.08±1.88)%, (30.19±3.07)% and (37.72±4.43)%, respectively, and the difference was statistically significant among groups(F = 65.828, P < 0.01). After treated with 3 mmol/L NaF for 24 h, the mRNA level of GRP78, GRP94 and CHOP was (1 172.41±459.60)%, (946.95±635.85)% and (7 846.97±1 670.01)%, which was increased compared to those of the control groups [(100.00±1.77)%, (100.00±2.08)%, (100.00±0.74)%,t = 12.77, 4.67, 11.50, all P < 0.01]. Under the same condition, the protein levels of GRP78 and CHOP were (159.99±67.59)% and (155.15±94.24)%, which were increased compared to those of the control groups [(100.00±30.68)%, (100.00±41.44)%,t =-3.27,-1.99, all P < 0.05], while GRP94 protein level [(46.40±41.46)%] was decreased compared to that of the control group [(100.00±68.86)%, t = 4.02, P < 0.05]. Conclusion Endoplasmic reticulum stress may be involved in NaF-induced cell death in HepG2 cells. Key words: Stress; Fluorides; Apoptosis