The efficacy of the quercetin analogue LY294002 in immortalized cancer cell lines is related to the oxygenic and metabolic status of cells

Purpose: LY294002, a promising drug for chemotherapy, suppresses the activity of Phosphatidylinositol 3-Kinase (PI3K) which is pivotal to a number of processes such as proliferation, metabolism, and apoptosis. The compound has, however, been seen to have very variable efficacy in vivo.Methods: Proliferation and viability of two immortalized cells with divergent bioenergetic profiles was determined using crystal violet staining, and the 3-(4, 5-dimethylthiazol-2yl)-2, 5-diphenyl tetrazolium bromide (MTT) assay. Oxygen consumption rates were determined using MitoXpress-Xtra probes, and lactate generation was assessed with pH-Xtra probe and BM-lactate strips. Immunoblotting was performed with phospho-Akt-Ser 473 and Akt-pan primary antibodies.Results: U87 cells were shown to have a glycolytic metabolism, whereas RD cells exhibited a more aerobic metabolism. In both lines, hypoxia was shown to increase lactate production, and LY294002 reduced lactate production. The drug decreased cell proliferation and viability under all conditions, but the effect was greatest in U87 cells under normoxic conditions.Conclusion: Metabolic analysis showed a link between a glycolytic cell status and LY294002 induced cell death. However, in both cell lines the drug was also less effective under hypoxic conditions, as would be found in a tumour in vivo. Furthermore, in the presence of LY294002 the phosphorylation status of Akt, a target of PI3K, was found to be related to both the mechanism of cell respiration, and the oxygenic status of the cells