The apoptosis-inducing effect of MnSOD_m on K562 cells and its molecular mechanism

Aim To explore the apoptotic effect of mimics of manganese superoxide dismutase(MnSODm)on human leukemia cell line K562 in vitro and the possible molecular mechanisms.Methods Human leukemia K562 cells were used as the target cells.The cell proliferating activity was examined by a MTT colorimetric assay,and the apoptosis of K562 cells was assessed with FITC-Annexin V and propidium iodide(PI)double staining and morphological changes.The expressions of bcl-2 and bax mRNA were detected by reverse transcription polymerase chain reaction(RT-PCR),and flow cytometry(FCM)was employed to measure the expressions of Bcl-2 and Bax protein,mitochondrial inner membrane potential(Δψm),Cytochrome C(Cyt C)release and Caspase-3 activity.Results The proliferation of K562 cells was obviously inhibited by 0.5~10 mg·L-1 MnSODm(P0.01),and the apoptosis rate of K562 cells detected with Annexin V/PI staining was markedly increased,and the typical apoptotic morphological changes of K562 cells was observed under optical and electronic microscopic morphology.The down-regulation of expressions of bcl-2 mRNA and protein was accompanied with the up-regulation of bax mRNA and protein.The disruption of mitochondria Δψm and the increased release of Cyt C from mitochondria to cytoplasm were noted,and the activity of Caspase-3 was significantly enhanced.Conclusions MnSODm can induce apoptosis of K562 cells via mitochondrial pathway by regulating the expression of Bax/Bcl-2.