Figure 5
Inhibition of the PI3k/Akt pathway promotes apoptosis by activation of caspase-3. (A) Left, A549 cells were serum-starved and treated or non-treated (control) with ATRA for 48 h, during the first 12 h after treatment with ATRA, the cells were irradiated with 150 J/m2 of UV-C light for 30 min. Subsequently, DNA fragmentation was detected by TUNEL according to the manufacturer’s instructions. The apoptotic cells are stained brown. Bar, 20 μm. Right, percentages of TUNEL-positive cells were quantified by counting 200 cells from four random microscopic fields (means ± SEM, *P < 0.05 compared with non-treated cells (control) assessed by t test analysis). (B) A549 cells were treated for 48 h with 5 μM of ATRA alone or combined with 5 μM of 15e. Subsequently, DNA fragmentation was detected by TUNEL. Control cells were non-treated. Percentages of TUNEL-positive cells were quantified by counting 200 cells from four random microscopic fields. Means ± SEM, *P < 0.05; **P < 0.001 compared with non-treated cells (control) (analysis of variance and Newman-Keuls test). (C) A549 cells were serum-starved and treated or non-treated (control) with 5 μM of ATRA alone or combined with 5 μM of 15e for 48 h. The cells were fixed, stained with anti-cleaved caspase-3 followed by donkey anti-goat FITC as described in Materials and Methods and analyzed by fluorescence microscopy. Bar, 20 μm.