Sodium sulfite promotes the assembly and secretion of very low-density lipoprotein in HL-7702 hepatocytes

This study investigated the effects of Na(2)SO(3) on the fat metabolism in human normal diploid HL-7702 (referred as L-02) hepatocytes. After 24 h and 48 h, treatment with different concentrations of Na(2)SO(3), the intra and extra-hepatocellular triglyceride (TG) contents of L-02 were determined using chemical-enzymatic method. The contents of very low-density lipoprotein (VLDL) and apolipoprotein B100 (apoB100) in the culture supernatants were determined using enzyme-linked immunosorbent assay (ELISA). Western blot was applied to detect the expressions of fatty acid oxidation and fat synthesis related proteins, VLDL assembly and secretion in L-02 cells. RESULTS: Na(2)SO(3) treatment (10 mM, 24 h/48 h) significantly increased the intra TG level in the hepatocytes. Different concentrations of Na(2)SO(3) increased the extra-hepatocellular TG content. After 24 h exposure, the extracellular VLDL levels and secretions of apoB100 in 0.1–10 mM Na(2)SO(3) groups were significantly higher than that of the negative control (P < 0.05). Meanwhile, the expression of CPT1 and SREBP1 protein were significantly reduced by Na(2)SO(3). MTP and TGH protein expressions were significantly elevated in each Na(2)SO(3) treatment group. The expression level of LDLR in hepatocytes was reduced by Na(2)SO(3). CONCLUSION: Na(2)SO(3) exposure may promote the hepatocellular VLDL assembly and secretion, through increasing of MTP and TGH expressions and inhibiting the uptake of extracelluar VLDL.