[Study of triptolide-induced apoptosis in MUTZ-1 cells and its allied mechanism]

To investigate the apoptotic effect of triptolide on MDS cell line MUTZ-1 cells and its mechanism, MUTZ-1 cells were incubated with indicated concentrations of triptolide. The growth of MUTZ-1 cells was observed by MTT assay and apoptosis was detected by DNA fragmentation analysis and flow cytometry using Annexin V-FITC/PI staining. The gene and protein expressions were determined by reverse transcription polymerase chain reaction (RT-PCR) and Western blot, respectively. The results showed that MUTZ-1 cell viability in presence of triptolide decreased markedly in a dose- and time-dependent manner. The growth-inhibitory IC50 value for triptolide treatment was 55.06 ng/ml. A DNA ladder pattern of internucleosomal fragmentation was observed. The translocation of phosphatidylserine at the outer surface of the cell plasma membrane could be induced by triptolide and its level increased following the augmentation of the drug concentration. Treatment of MUTZ-1 cells with triptolide for 12 hours resulted in the activation of caspase-3, cleavage of PARP and decrease of c-IAP2 mRNA. The expressions of pro-caspase 3 and c-IAP2 were inversely correlated with the incidence of apoptosis. (r = -0.907, P = 0.000; r = -0.919, P = 0.000 respectively). In conclusion, Triptolide inhibits MUTZ-1 cell growth by inducing apoptosis. The apoptotic effect of triptolide in MUTZ-1 cells is mediated by the caspase-3 activation and PARP cleavage. Moreover, the activation of caspase-3 may be associated with the down-regulation of c-IAP2.