Enhancing effect of chidamide on the sensibility of human chronic myeloid leukemia K562/ADM cells to daunorubicin / 解剖学报

ABSTRACT

Objective: To investigate whether chidamide (CDM) could influence the sensibility of human chronic myeloid leukemia K562/ADM cells to daunorubicin (DNR) and its possible mechanism. Methods: The K562 and K562/ADM cells were cultured in vitro and treated with CDM and(or) DNR for 48 hous, and then the cell viability was measured by cell counting kit-8(CCK-8) assay. The proliferation, cell cycle and apoptosis were analyzed by flow cytometry. Western blotting was performed to measure the protein levels of histon 2AX (H2AX), γH2AX (Serl39), ataxia telangiectasia mutated gene (ATM), p-ATM (Serl981), breast cancer susceptibility protein 1(BRCAl), and p-BRCAl (Serl524). Results: DNR remarkably inhibited the cell activity of K562/ADM cells in dose-dependent manner with a half maximal inhibitory concentration(IC50) value of 11.76 μmol/L, and the resistant factor was 18.09. Co-treatment with CMD and DNR produced a synergistic effect confidence interval(GI) (CI<1) with a reversal fold of 8.11. DNR remarkably inhibited proliferation (P<0.05), induced G2/M phase arrest and apoptosis (P<0.05), these effects were enhanced under non-toxic concentration of CMD (P<0.05). K562/ADM cells had a significantly higher protein levels of ATM and BRCA1 than K562 cells (P<0.05). DNR significantly up-regulated the protein levels of γH2AX, p-ATM and p-BRCAl (P<0.05), and the protein level of γH2AX appeared higher in the combination group compared to DNR alone (P<0.05); however, the co-treatment with CMD and DNR induced a decreased expression of p-ATM and p-BRCAl than the DNR alone (P< 0.05). Conclusion: CDM may enhance the sensibility of K562/ADM cells to DNR by up-regulating the protein level of γH2AX, and down-regulating the protein levels of p-ATM and p-BRCAl.