Reversal of apoptosis resistance of doxorubicin-resistant human myeloge-nous leukemia cell line K562/DOX by a cyclosporin D analogue PSC833 / 中国病理生理杂志

ABSTRACT

AIM:To study the reversal effect of a cyclosporin D analogue PSC833 on multidrug resistance of doxorubicin-resistant human myelogenous leukemia ( K562/DOX) cells.METHODS: The reversal effects of PSC833 on resistance to doxorubicin ( DOX)/vincristine ( VCR) in K562/DOX cells were observed by MTT assay.The cell cycle analysis was performed by flow cytometry.Annexin V/PI staining was used to identify PSC833-induced apoptosis in K562/DOX cells.These cells underwent incubation with DCFH-DA, JC-1 and Fluo-3/AM followed by flow cytometry for the measurement of reactive oxygen species ( ROS) , mitochondrial membrane potential (ΔΨm ) , and intracellular calcium, re-spectively.The protein levels of cytochrome C (Cyt C), Bcl-2, Bax, and cleaved caspase-3 were detected by Western blotting.RESULTS:The DOX/VCR-induced cytotoxicity was significantly potentiated by PSC833.PSC833 arrested the cells in G2/M phase and increased the apoptosis induced by DOX in K562/DOX cells.During the apoptosis, the level of ROS and intracellular calcium increased, while the level ofΔΨm decreased.Furthermore, the release of Cyt C, activation of caspase-3, up-regulation of Bax and down-regulation of Bcl-2 were observed in K562/DOX cells treated with PSC833 and DOX.CONCLUSION: The reversal effect of PSC833 on multidrug resistance in K562/DOX cells is associated with the induction of apoptosis through a mitochondria-dependent pathway.