Fig. 5

Casticin inhibits the PI3K/mTOR/AKT pathway in BYL719-insensitive cells. a Measurement of the IC50 of BYL719 in 12 NPC cell lines after 72 h of treatment by examining its effects on viability. Values are shown as the mean ± standard error of the mean (SEM). Data points represent combined values across triplicate samples. b Apoptosis (annexin V) in BYL719-sensitive and BYL719-insensitive NPC cells after 48 h of treatment with 1 μM BYL719. Each dot represents the mean of three independent experiments, each performed in duplicate per listed cell line. *p < 0.05 versus insensitive. c After treatment with 1 μM BYL719 for 48 h, sensitive cell lines had, on average, a larger proportion of cells in cell cycle arrest (S-phase arrest) than did insensitive lines. Each dot represents the mean of three independent experiments, each performed in duplicate per listed cell line. *p < 0.05 versus insensitive. d, e Western blotting results showing PI3K pathway signalling in BYL719-insensitive resistant and BYL719-sensitive NPC cell lines. Protein lysates from cells treated with 1 μM BYL719 were extracted at different time points and analysed by Western blotting with the indicated antibodies. Densitometric analysis of Western blot bands is shown in the right panel. All data are presented as the mean ± SD, *p < 0.05 versus 0 h