LY294002, an Inhibitor of PI-3K, Enhances Heat Sensitivity Independently of P53 Status in Human Lung Cancer Cells

The aim of this study was to ascertain whether LY294002, an inhibitor of PI-3K, enhances heat sensitivity in human cancer cells regardless of their p53 status. Colony formation assays showed that LY294002 enhanced heat sensitivity in two human lung cancer cell lines; H1299/wild-type p53 (wtp53) and H1299/mutated p53 (mp53) cells. These cell lines have identical genetic backgrounds except for their p53 status. LY294002 suppressed the heat-induced accumulation of heat shock protein 27 (hsp27) and heat shock protein 72 (hsp72) in these cell lines. Heat-induced apoptosis was observed more frequently in H1299/wtp53 cells than in H1299/mp53 cells, and was enhanced by LY294002 in both cell lines. In addition, both the heat-induced phosphorylation of Akt and the accumulation of survivin were suppressed by LY294002. These results suggest that LY294002 inhibits anti-apoptosis signaling through hsp27 and hsp72 as well as cell survival signaling through Akt and survivin. LY294002 appears to be an attractive candidate for a p53-independent heat sensitizer in hyperthermic cancer therapy.