Effects of sodium nitrite on proliferation and apoptosis on human hepatocarcinoma cells

Aim To investigate the effects of nitrite-induced proliferation and apoptosis on human hepatocarcinoma cells in vitro.Methods The proliferation and time-dependent response of SMMC-7221 cells was measured by MTT after exposing to variant dosages of sodium nitrite.Apoptosis and mitotic index were routinely evaluated by fluorescence microscopic assay.The reverse transcriptase-polymerase chain reaction(RT-PCR)was used to detect changes of c-myc mRNA.The protein expression of hypoxia-inducible factor-1α(HIF-1α)in cells was revealed by Western blot.Results At low dosage range of 20 mg·L-1 to 200 mg·L-1,the proliferation of SMMC-7721 cell was promoted while apoptosis was suppressed simultaneously.At higher dosage range(800 mg·L-1),the scenario was reversed,which showed suppressed proliferation and enhanced apoptosis reciprocally.After being treated with 20～200 mg·L-1 sodium nitrite,SMMC-7721 cells expressed a high level of c-myc mRNA and HIF-1α protern significantly.Conclusions Sodium nitrite induced cell proliferation versus apoptosis in a biphasic dose-response fashion in human hepatocarcinoma SMMC-7721.