Objective: To investigate the effect of bortezomib in inducing apoptosis in imatinib-resistant K562 (K562R) cells and its possible mechanism.
Methods: K562 cells were cultured in gradient concentrations of imatinib for several months to generate imatinib-resistant K562 cells. The viability of K562R cells treated with bortezomib was measured using CCK-8 cell proliferation assay, and the cell apoptosis was analyzed by flow cytometry with annexin V/PI dual staining. Western blotting was used to detect the protein expressions of Mcl-1,Bcl-2 and Bcr/Abl.
Results: K562R cell line was successfully established, which showed 31.8 folds of imatinib resistance compared with the na?ve cells. Bortezomib treatment produced dose- and time-dependent inhibitory effect on the proliferation of both K562 cells and K562R cells and dose-dependently induced apoptosis in K562R cells. Combination of bortezomib with imatinib significantly enhanced the apoptosis of the cells. Western blotting showed that bortezomib treatment dose-dependently decreased the protein levels of both Mcl-1and Bcr/Abl in K562R cells without affecting bcl-2 protein expression.
Conclusion: Bortezomib can inhibit the proliferation of K562R cells and induce cell apoptosis possibly by down-regulating Mcl-1 and Bcr/Abl expression and enhancing Mcl-1 cleavage.
目的: 探讨硼替佐米对伊马替尼耐药细胞株K562（K562R）的诱导凋亡作用及机制。
方法: 采用浓度梯增法建立耐伊马替尼K562细胞系。应用CCK-8法检测不同浓度硼替佐米分别作用K562和K562R细胞24 h、48 h后, 对细胞的增殖抑制的效果。使用流式细胞术方法分别检测硼替佐米单独或联合伊马替尼作用于K562R细胞48 h后的细胞凋亡。应用Western blotting检测不同浓度硼替佐米作用K562R细胞48 h后, Mcl-1、Bcl-2、Bcr/Abl蛋白表达的异同。
结果: 成功将对伊马替尼敏感的K562细胞诱导为K562R, 耐药倍数为31.8；硼替佐米对K562及K562R细胞的增殖抑制呈浓度、时间依赖（P均＜0.05）；随着硼替佐米浓度增加, 对K562R细胞的诱导凋亡作用增强, 且硼替佐米与伊马替尼联合具有协同作用（P＜0.05）；硼替佐米可抑制K562R细胞Mcl-1, Bcr/Abl蛋白的表达, Bcl-2无变化。
结论: 硼替佐米具有对K562R细胞的增殖抑制和诱导凋亡作用, 其机制可能与下调K562R细胞Bcr/Abl和MCL-1的表达以及促进MCL-1发生切割有关。