中文摘要：

目的探讨蟾毒灵对人白血病多药耐药K562/VCR细胞株增殖抑制的作用及其可能的机制。方法采用MTT比色法测定蟾毒灵对多药耐药K562/VCR细胞株的增殖抑制率,倒置显微镜及Wright-Giemsa染色法观察细胞形态学改变,流式细胞术（FCM）分析蟾毒灵对K562/VCR细胞株细胞周期分布的影响,免疫细胞化学法检测耐药细胞中胸苷酸合酶（TS）表达的变化。结果蟾毒灵能够显著抑制人白血病多药耐药K562/VCR细胞株的增殖,0.01μmol/L的蟾毒灵即可诱导耐药细胞出现典型的细胞凋亡形态学特征,FCM细胞周期分析显示G2/M期细胞比率减少、＂亚G1期＂细胞增多,0.001μmol/L的蟾毒灵可显著下调K562/VCR多药耐药细胞中TS蛋白的表达。结论人白血病多药耐药K562/VCR细胞株对蟾毒灵无交叉耐药性,蟾毒灵可诱导耐药细胞周期阻滞和细胞凋亡,下调TS蛋白可能是蟾毒灵抑制多药耐药细胞株增殖的机制之一。

英文摘要：

Objective To investigate the effect of bufalin on the proliferation of multidrug-resistant human leukaemia K562/VCR cell line and to explore its possible mechanism.Methods Proliferative inhibition rate was determined by MTT colorimetric assay.Cell morphology was observed by inverted microscope and Wright-Giemsa staining method.Cell cycle was analyzed with flow cytometry （FCM）.Expression of thymidylate synthase （TS） protein was measured by immunocytochemistry.Results Bufalin remarkably inhibited the proliferation of K562/VCR cell line.Bufalin （0.01 μmol/L）could induce typical morphological changes of apoptosis as observed under light microscopy.The results of cell cycle analysis presented increased sub-G1 proportion and apoptosis rate,as well as apparent decrease of cell number in the G2/M phase after treatment with Bufalin.TS protein expression was decreased markedly after treatment with Bufalin （0.001μmol/L）.Conclusion K562/VCR cell line has no cross-resistance to bufalin.Bufalin could induce cell cycle arrest and apoptosis.Down-regulation of TS protein might be one of the mechanisms of bufalin on cell proliferative inhibition.