Effect of Cell Autophagy on the Apoptosis of Hepatocellular Carcinoma Cells Induced by Arsenic Trioxide

Objective: To determine the effect of autophagy on the apoptosis of hepatocellular carcinoma cells induced by arsenic trioxide (ATO).

Methods: Hepatocellular carcinoma HepG2 cells were exposed to ATO. The cell viability was detected by MTT after adjustments for autophagy agonist (Rap) and autophagy inhibitor (3-MA). The autophagosome was observed under electronic microscope. The autophagy related proteins (LC3 and Beclin1) were detected by immunofluorescence. The cell apoptosis was measured by flow cytometry.

Results: With 5-20 μmol/Lof ATO, HepG2 cells exposed to 3-MA had significantly lower viability (P <0.05) and higher early apoptosis (P <0.05) than those without exposure to 3-MA. Exposure to 3-MA was also associated with lower expressions of LC3 and Beclin1, with HepG2 cells showing typical apoptotic characteristics. By contrast, with 5-20 μmol/Lof ATO, the cells exposed to Rap showed significantly higher viability (P <0.05) and lower early apoptosis (P<0.05) than those without exposure to Rap. A large number of autophagosome appeared in the cells exposed to Rap. Exposure to Rap was associated with increased expressions of LC3 and Beclin1, but with no statistical significance (P >0.05).

Conclusions: Targeted autophagy inhibition can significantly increase the sensitivity of HepG2 to ATO. The underlining mechanism is associated with enhanced apoptosis of hepatocellular carcinoma cells.