Treatment with NVP-BEZ235 delays tumor progression in vivo in a xenograft model of PEL. (A) Tumor progression is significantly delayed (P < .001) in mice treated with 40 mg/kg NVP-BEZ235 administered by oral gavage. Mice were treated 5 times per week with NVP-BEZ235 (n = 7) or vehicle (n = 6) after the development of palpable tumors. Mice were followed for 20 days, at which point vehicle-treated mice were killed. NVP-BEZ235–treated mice had significantly smaller tumors. Error bars represent the SD for each group of animals. (B) Immunohistochemical analyses reveal decreased phosphorylation of ribosomal S6 protein and Akt (Ser473) in NVP-BEZ235–treated mice. No staining was observed in sections that had not been incubated with specific antibodies. (C) PI3K/Akt inhibition induces apoptosis in PEL. A total of 1 × 106 BC-1 PEL cells were treated with 50μM miltefosine, 50μM perifosine, or 20nM NVP-BEZ235, and the appropriate vehicle controls. Cells were harvested and lysed 12 hours later. Equivalent micrograms of cell lysate for all samples were incubated with a fluorogenic caspase-3 substrate (DEVD-AFC). Caspase-3 cleavage of the fluorescent DEVD substrate was measured on a fluorometer. The percentage of caspase-3 activity in BC-1 cells after incubation with perifosine, miltefosine, or NVP-BEZ235 was calculated compared with vehicle-treated cells. Percentage increase in caspase-3 activity of drug-treated cells compared with the respective vehicle control-treated cells is shown on the y-axis, and the specific inhibitor is shown on the x-axis.
