OBJECTIVETo explore the effect of Imatinib mesylate on proliferation, differentiation and apoptosis of leukemic Kasumi-1 cells bearing c-kit mutation.

METHODSKasumi-1 cells were treated with Imatinib at different concentrations in culture. Cell proliferation was assayed by MTT assay, expressions of c-kit antigen, surface myeloid antigen and cell cycle by flow cytometry, cell apoptosis by annexin V staining and agarose gel electrophoresis. Western blot was used to analyze the level of c-kit protein tyrosine phosphorylation.

RESULTSImatinib treatment caused a time- and dose-dependent inhibition of the cell proliferation, with a 72 h IC50 of 4.45 micromol/L. Imatinib treatment induced a decrease in the mean fluorescence value of c-kit antigen, a progressive decline in S-phase cell fraction and an increase in G0/G1 cells. Treatment with 5.00 micromol/L of imatinib for 72 h induced an increase in expression of myeloid surface protein CD11, CD13 and CD15, and for 24 h induced an increase in early apoptosis cells [from 9.04% to 86.84% (P < 0.05)]. The apoptosis ladder was observed on agarose gel electrophoresis on 5-day treatment. Tyrosine phosphorylation level of c-kit protein was decreased by Imatinib treatment.

CONCLUSIONTyrosine kinase inhibitor Imatinib mesylate treatment could inhibit proliferation of Kasumi-1 cells which bear a c-kit mutation, induce differentiation, apoptosis and G0/G1 cells accumulation.