Figure 5. Dual PI3K/mTOR inhibitors induce apoptosis in OS cells.

(A) Analysis of target inhibition downstream of PI3K/mTOR activity was assessed by western blot of the indicated proteins against murine fibroblastic, murine osteoblastic and primary human OS. Each cell type was treated with the calculated IC₅₀ and Emax respectively for each drug. (B) Cell cycle distribution of murine fibroblastic OS or primary human OS cells treated with the indicated concentrations of GSK2126458 and PKI587 for 24hrs, statistical comparison performed comparing the proportions of G0/G1 phase cells between vehicle and each treatment. (C) GSK2126458 and PKI587 induce apoptosis as assessed by annexin V/7AAD staining (D) or cleaved caspase-3 western blot in a dose dependent manner. Where indicated data presented as mean ± SEM, *P<0.05, **P<0.01, ***P<0.001 (n=3 technical replicates per cell line, 3 independent cell lines tested as indicated).