Figure 8. Bortezomib promotes sensitivity to PI3K pathway inhibition.

(a) Western blot analysis of PI3K pathway activity in ras^G12V p53^Ri pten^Ri apc^Ri hindguts after 1 day feeding of bortezomib at indicated doses. Each data point represents the average response of two to five biological replicates with ten hindguts per replicate. Error bars: s.e.m. (b) Quantification of dissemination in ras^G12V p53^Ri pten^Ri apc^Ri animals after sequential treatment with BEZ235 and indicated doses of bortezomib. (c) Quantification of dissemination in ras^G12V p53^Ri pten^Ri apc^Ri animals after a 1-day/2-day alternating treatment schedule of bortezomib/BEZ235 and each drug alone. (d) Western blot analysis of PI3K pathway activity in ras^G12V p53^Ri pten^Ri apc^Ri hindguts with and without raptor knockdown treated with 5 μm bortezomib for 1 day. (e) Quantification of dissemination in ras^G12V p53^Ri pten^Ri apc^Ri raptor^Ri animals after sequential treatment with indicated doses of bortezomib followed by BEZ235. (f) Schematic illustration of the mechanism by which the two-step therapy overcomes resistance to BEZ235: elevating mTORC1 activity increases subsequent sensitivity to BEZ235. (b,c,e) n=2 replicates, 30 flies per replicate; error bars: s.e.m. *P<0.01 and **P<0.05 (Fisher's exact test). Drug doses reflect concentrations in the food. Uncropped gels used to generate panels a and d can be found in Supplementary Fig. 8e,f.