RÉSUMÉ
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.
RÉSUMÉ
In order to investigate the anti-cancer effects of deguelin and on K562 and K562/ADM cells in vitro and the underlying molecular mechanism and compare the cytotoxicity of deguelin on K562, K562/ADM cells and human peripheral blood mononuclear cells (PBMCs). The effects of deguelin on cell proliferation were assessed by MTT assay. Apoptosis were detected by AnnexinV/PI double-labeled cytometry. The effects of deguelin on the cell cycle were studied by a propidium iodide method. Our study showed that deguelin inhibited the proliferation of K562 cell and K562/ADM cell in a time- and dose-dependent manner and had minimal effects on normal human peripheral blood mononuclear cells. The ratio of IC50 value of deguelin of 24 h on K562/ADM cells to K562 cells was only 1.27, which was significantly lower than the ratio of IC50 value of ADM (higher than 20). Deguelin could induce apoptosis of K562 cells and K562/ADM cells. K562 cells were arrested at G2/M phase while K562/ADM cells were arrested at G0/G1 phase. Our results suggested that deguelin was a novel anti-leukemia agents with high efficacy and low toxicity and it is also a promising agent for reversing drug resistance.