Hsp90抑制剂新生霉素诱导K562细胞凋亡的机制

Mechanisms of apoptosis in K562 cells induced by Hsp90 inhibitor novobiocin

目的研究Hsp90抑制剂新生霉素（novobiocin，NB）诱导K562细胞凋亡的作用，探讨该作用与线粒体凋亡途径的关系，并进一步研究NB对Hsp90客户蛋白（client protein）AKT和ERK功能的影响。方法细胞用NB处理后，采用AO／EB双染后检测细胞凋亡，分光光度法检测Caspase-9和Caspase-3的活性，用蛋白免疫印迹法检测细胞色素C的含量，以及procaspase-3、p-AKT和p-ERK的蛋白水平。结果NB能显著抑制K562细胞增殖，IC50是0．4353mM；NB能促进细胞色素C释放入胞浆，激活caspase-3／9的活性，触发K562细胞凋亡；NB能抑制AKT和ERK的功能，使细胞内p-AKT和p-ERK的蛋白含量减少。结论NB可通过线粒体途径诱导K562细胞凋亡，还可干扰Hsp90伴侣功能阻断增殖信号通路，抑制K562细胞生长。

Aim In an effort to confirm the effects of Hsp90 inhibitor novobiocin（NB） on K562 cells, to reveal the relationship between NB-induced apoptosis and mitochondrion pathway, and to further clarify the mechanism of growth inhibition, The function of Hsp90 client protein AKT and ERK were also measured. Methods When K562 cells were treated with NB, the typical morphological changes of apoptosis were observed by AO/EB examined by fluorescence microscopy. The activities of Caspase-9 and Caspase-3 were analyzed by spectrophotometry. The amounts of cytochrome C in cytosolic and S-100 fraction, procaspase-3, p-ERK, and p-AKT were tested by Western blot, Results NB was a potent inhibitor of proliferation of K562 cells with IC50 values of 0.4353 mM; NB induced cytosolic accumulation of cytochrome c and activities of caspase-3/9, triggering apoptosis of K562 cells, NB inhibited the function of AKT and ERK with downregulation of p-ERK and p-AKT, Conclusions NB might induce the apoptosis of K562 cells by mitochondrion pathway. The K562 cells growth inhibition might also be involved in disruption of Hsp90 chaperon function.