Abstract: OBJECTIVE: To study the expression and function of poly ADP-ribose polymerase-1(PARP-1) in mitoxantrone-induced drug-resisatance MCF-7 cells and analyse its drug-resistance mechanism. METHODS: MCF-7 cells were exposed to mitoxantrone in six concentration groups,0.005, 0.01, 0.02, 0.04, 0.08 and 0.16 μmol/L, for 30 days in turn with one blank control group. Both real-time quantitative RT-PCR and Western blot were used to measured PARP-1 expression. RESULTS: PARP-1 expression in MCF-7 cell was increased and displayed dose-effection relationship when exposed to higher concentrations of mitoxantrone, compared with the control group. There was a significant difference on PARP-1 expression when MCF-7 cells were exposed to mitoxantrone,0.02,0.04 and 0.08 μmol/L(P<0.05). CONCLUSION: PARP-1 expression was increased in MCF-7 cells after prolonged exposure to mitoxantrone and it could have participated in the formation of drug resistance in these cells.

Key words: mitoxantrone, PARP-1, drug resistance