Ilnytska O. Regulation of phosphatidylinositol 3-kinase signalling specificity during the cource of differentiation and apoptosis in human erythroleukemia cell line K562

The object: PI-3-kinase signalling. The aim to explore regulation of PI-3-kinase signalling specificity under the action of tyrosine kinase inhibitors, herbimycin A and quercetin, and tumor promoter PMA in human erythroleukemia cell line K562. The methods: cytomorphology, comet assay, DNA and protein electrophoresis, GST-p85? fishing assay, Western blotting, PI-3-kinase assay, thin layer chromatography, correlation and multiple regression analysis. It has been found that herbimycin A, quercetin and PMA affect differently proliferation, differentiation and apoptosis of K562 cells, suggesting that these agents have various molecular mechanisms of action on cells. It was revealed differences in phosphorylation level of p210 Bcr-Abl and in PI-3-kinase activity of upon treatment of cells with herbimycin A and quercetin. It was shown that binding of signalling proteins with regulatory p85 subunit of PI 3-kinase in intact K562 cells had a small modulating effect on enzyme activity. Correlation and multiple regression analysis of protein-protein interaction dynamics for p85 alpha and dynamics of PI-3-kinase activity during K562 erythroid and megakaryocytic differentiation induced by herbimycin A and PMA, respectively, showed that the number of proteins, in particular p120c-Cbl negatively regulate PI 3-kinase activity. Obtained data suggest that binding of majority of signalling proteins with p85 alpha in quercetin-treated cells has stimulatory effect on PI 3-kinase activity. Field of application: cell biology, biochemistry.