A High-Throughput Liposome Substrate Assay with Automated Lipid Extraction Process for PI 3-Kinase

The signaling pathways involving lipid kinase class I phosphatidylinositol 3-kinases (PI 3-kinases) regulate cell growth, proliferation, and survival. Class I PI 3-kinases catalyze the conversion of PI (4.5)P-2 to PI (3.4,5)P-3, which acts as a lipid second messenger to activate mitogenic signaling cascades. Recently, p110 alpha class IA PI 3-kinase, was found to be mutated frequently in many human cancers. Therefore. it is increasingly studied as an anticancer drug target. Traditionally, PI 3-kinase activities have been studied using liposome substrates. This method, however, is hampered significantly by the labor-intensive manual lipid extraction followed by a low-throughput thin-layer chromatography analysis. The authors describe a high-throughput liposome substrate-based assay based on an automated lipid extraction method that allows them to study PI 3-kinase enzyme mechanism and quantitatively measure inhibitor activity using liposome substrates in a high-throughput mode. This improved assay format can easily be extended to Study other classes of phosphoinositide lipid kinases. (Journal of Biomolecular Screening 2008:906-911)