Fig. 4

Inhibition of autophagy resulted in increased apoptotic cell death in SR-T100-treated primary epithelial cells expressing HPV 16-E6/E7 and HPV18-E6/E7. a Wortmannin (WT) and 3-MA inhibited early autophagy activities in SR-T100-treated primary epithelial cells expressing HPV-E6/E7. Immunoblotting for LC3I/II using lysates from primary epithelial cells expressing different types of HPV-E6/E7 that were pretreated with the autophagy inhibitors wortmannin (WT) (200 nM) or 3-MA (2.5 mM) and then treated with or without SR-T100 (5 μg/ml) for 12 h. The blots were stripped and reprobed with an anti-β-actin antibody to ensure equal protein loading. Similar results were observed in three independent experiments. The number indicates the fold change in the LC3-II/actin ratios in cells treated with SR-T100 versus those without SR-T100 treatment. b Histograms show the number of apoptotic SR-T100-treated (5 μg/ml) cells (Annexin V-positive) that were incubated in the presence or absence of WT and 3-MA for 12 h. The cells were incubated with SR-T100 (5 μg/ml) in the presence or absence of the autophagy inhibitors WT or 3-MA for 12 h. At the end of the treatments, the cells were double labeled with Annexin V-FITC and propidium iodide (PI) and analyzed by flow cytometry to evaluate cell viability. WT and 3-MA significantly increased apoptotic cell death in primary epithelial cells expressing HPV16-E6/E7 and HPV18-E6/E7. The data represent the mean ± SD from three independent experiments. *P < 0.05; **P < 0.01. c The LC3-I and LC3-II proteins were detected by western blotting. The primary epithelial cells were infected with different types Lenti-HPV-E6/E7 virus for 24 h. After 24 h, the infected cells were incubated in culture medium in the presence or absence of the pan-caspase inhibitor Z-VAD-FMK (50 μM) for 30 min and then treated with SR-T100 (5 μg/ml) for 12 h. d The panel shows the percent change in the LC3-II/actin ratio compared with the untreated group in three independent experiments