Fig. 6

The PI3K/AKT pathway is a determinant of the responsiveness of GBM cells to MTH1 inhibition. a Lysates were collected at multiple time points from U251 cells expressing either a control shRNA plasmid or an MTH1 shRNA to confirm MTH1 knockdown. b Decreased expression of MTH1 increased the sensitivity of U251 cells to BKM120. c (Left) Single and combinatorial titration of GDC-0941 and TH588 cells in the 3 days growth assay in U251 cell lines. GDC-0941 is a highly specific pan-PI3K inhibitor. (Right) Analysis of GDC-0941 and TH588 interaction and the resulting Fa-CI plots. d (Left) Single and combinatorial titration of GDC-0068 and TH588 cells in the 3 days growth assay in U251 cell lines. GDC-0068 is a novel, highly selective, orally available ATP-competitive pan-AKT inhibitor. (Right) Analysis of GDC-0068 and TH588 interaction and the resulting Fa-CI plots. e Same as (d), but for MK2206, a potent, oral allosteric AKT inhibitor. f Basal levels of PTEN, p-AKT473, p-AKT308, p-S6 and p-4EBP1 in a panel of eight GBM cells were determined by Western blot analysis. g A panel of eight GBM cells was incubated with different concentrations of BKM120 for 72 h. h Levels of PTEN, p-AKT473, p-AKT308, p-S6 and p-4EBP1 in LN229, LN229 with inducible PTEN knockdown, LN229 with PIK3CA mutant 1 and 2 were determined by Western blot analysis. i Cell viability assay in LN229, LN229 with inducible PTEN knockdown, LN229 with PIK3CA 1 mut (p.E542K) or LN229 with PIK3CA 2 muts (p.N345K and p.E542K) treated with TH588. Error bars represent the standard error of the mean (SD). j Western blot analysis of AKT overexpression in HeLa cells. k Cell viability assay in HeLa cells with AKT overexpression treated with TH588. Error bars represent the standard error of the mean (SD)