地西他滨对K562/A02细胞阿霉素耐药性的影响

 目的: 观察地西他滨(DAC)对人慢性粒细胞白血病耐药细胞株K562/A02阿霉素(ADR)耐药性的影响,探讨其作用的可能机制。方法: 分别或联合应用不同浓度ADR和DAC作用于K562/A02细胞和其亲本细胞株K562,采用CCK-8法检测药物细胞毒性,Sequenom MassARRAY系统结合比色法评价DNA甲基化程度,流式细胞术检测K562/A02细胞细胞周期分布和细胞凋亡率。结果: K562/A02细胞较K562细胞具有显著ADR耐药性,前者ADR作用24 h的IC₅₀约为后者的50倍。而对DAC,在0.5~8 μmol/L作用浓度范围内,K562/A02细胞则较K562细胞更敏感。在相同ADR作用浓度(4.31和17.24 μmol/L)下,联合1 μmol/L DAC处理24 h能显著提高K562/A02细胞对ADR的敏感性,细胞存活率下降(P<0.05)。DAC和ADR均能影响K562/A02细胞的细胞周期进程和细胞凋亡率。1 μmol/L DAC的影响与作用时间相关,在作用24 h时以S期阻滞与细胞早期凋亡率升高为主,48 h时以G₂/M期阻滞与细胞晚期凋亡和坏死率升高为主。ADR则主要表现为浓度依赖性G₂/M期阻滞并诱导细胞晚期凋亡和坏死。两者联用使ADR对细胞周期分布的作用进一步加强,即表现为G₂/M期阻滞更加明显,但对细胞凋亡率的影响并无显著差异。而在基因组甲基化程度上,2种细胞没有显著差异,DAC作用前后也没有显著改变。结论: DAC能增强K562/A02细胞对ADR的敏感性,具有逆转耐药作用,其机制可能与调节K562/A02细胞细胞周期进程、促进细胞凋亡和坏死有关。

Effect of decitabine on resistance of K562/A02 cells to adriamycin

AIM: To investigate the effect of decitabine (DAC) on the resistance of human chronic myeloid leukemia cell line K562/A02 to adriamycin (ADR), and to explore the possible mechanism. METHODS: The K562/A02 cell line and its parental cell line K562 were treated with different concentrations of ADR or DAC alone, or in combination. The cytotoxic effects of these 2 agents were determined by CCK-8 assay. The degree of DNA methylation was evaluated by Sequenom MassARRAY system and colorimetric method. The cell cycle distribution and the apoptotic rate were determined by flow cytometry. RESULTS: K562/A02 cells were more significantly resistant to ADR than K562 cells.The half maximal inhibitory concentration of ADR for 24 h of the K562/A02 cells was about 50 times higher than that of the K562 cells. To DAC, in the concentration range of 0.5~8 μmol/L, K562/A02 cells were more sensitive than K562 cells. As compared with the same concentrations (4.31 μmol/L and 17.24 μmol/L) of ADR alone, the combination with 1 μmol/L DAC significantly improved the sensitivity of K562/A02 cells to ADR. Both DAC and ADR affected the cell cycle progression and apoptotic rate of K562/A02 cells. DAC (1 μmol/L) treatment mainly showed S phase arrest and increased early apoptotic rate for 24 h, and G₂/M phase arrest and increased late apoptosis and necrosis for 48 h in a time-related manner. ADR treatment showed G₂/M phase arrest and increased late apoptosis and necrosis in a concentration-dependent manner. In combination with 1 μmol/L DAC, the effect of ADR on the cell cycle distribution was further enhanced, showing more obvious G₂/M phase arrest, but no significant difference of the apoptotic rate was observed. The degree of methylation in the genome had no significant difference between the 2 cells, and it before and after DAC treatment had no significant change. CONCLUSION: DAC enhances the sensitivity of K562/A02 cells to ADR, showing drug resistance-reversing potential. The mechanism may be related to regulating cell cycle progression and promoting apoptosis and necrosis of K562/A02 cells.