TNF? induces Ca2+ influx to accelerate extrinsic apoptosis in hepatocellular carcinoma cells.

ABSTRACT: Tumor necrosis factor-? has been proven an effective anticancer agent in preclinical studies. However, the translation of TNF? from research to clinic has been blocked by significant systemic toxicity and limited efficacy at maximal tolerated dose, which need urgently to be solved.The level of cytosolic Ca2+ was assessed by Fura-2 in HCC cells. After changing cytosolic Ca2+ level by using agonists or inhibitors, cell apoptosis was detected by flow cytometry. We also detected the effect of ionomycin or parvalbumin on the anti-tumor activity of TNF? in a mice model. Lastly, we studied the roles of cytosolic Ca2+ in the mitochondrial-dependent intrinsic apoptosis pathway.Here, we demonstrated that TNF? induced extracellular Ca2+ influx into cytoplasm through transient receptor potential channel in HCC cells. Both cytosolic Ca2+ scavenger and Ca2+-binding protein PV effectively desensitized hepatocellular carcinoma cells to TNF?, whereas combination ionomycin or 1,4,5-inositol triphosphate significantly sensitized HCC cells to TNF?, indicating that the increased level of cytosolic Ca2+ was positively correlated with the TNF?-induced cell apoptosis in vitro. In a nude mice xenograft model, our data revealed that TNF? combined with ionomycin remarkably synergized the anti-tumor effect of TNF?. Furthermore, we found that TNF?-mediated extracellular Ca2+ influx accelerated TNF?-induced extrinsic apoptosis through activating calpain/IAP/caspase3 pathway.Our study provides the evidence supporting a novel mechanism by which TNF? induces extracellular Ca2+ influx to enhance cell apoptosis and suggests that increasing the level of cytosolic Ca2+ might be an alternative strategy to improve the pro-apoptotic activity of TNF? in HCC cells, although suitable chemical or biological reagents need to be further tested.

SUBMITTER: Zhu J 

PROVIDER: S-EPMC5838867 | biostudies-other | 2018 Mar

REPOSITORIES: biostudies-other