Effect of mitoxantrone on proliferation and apoptosis of human multiple myeloma cell RPMI8226

Abstract

This study was aimed to investigate the effects of mitoxantrone on proliferation and apoptosis of human multiple myeloma cell line RPMI-8226 and its mechanism. The inhibitory rate of RPMI8226 cells proliferation was assayed by MTT, the morphological changes of RPMI-8226 cells were observed by inverted flurescent microscopy and transmission electron microscopy, the apoptosis rate and the cell cycle distribution of RPMI-8226 cells were detected by flow cytometry. The effects of mitoxantrone on the expression of BCL-2, BAX, caspase-3 mRNA were detected by RT-PCR, the BCL-2, BAX, caspase-3 protein expression of RPMI-8226 cells was analyzed by Western blot. The results showed that mitoxantrone could inhibit the proliferation of RPMI-8226 cells in time- and dose-dependent manners. Light microscopy showed that the cell number in mitoxantrone group was significantly less than that in control group and the cell growth arrangement was irregular, apoptotic cells could be seen. Under electron microscope, typical apoptotic morphological and ultrastructural changes could be observed, these results confirmed that the mitoxantrone could induce apoptosis of RPMI-8226 cells, the difference have statistical significance (P < 0.05). The 1.0 µg/ml low concentration of mitoxantrone mainly arrested RPMI-8226 cells in the G2/M phase(P < 0.05), and the 2.0 µg/ml high concentration of mitoxantrone mainly arrested RPMI-8226 cells in the S phase (P < 0.05). The expression of BCL-2 mRNA decreased (P < 0.05),while the expression of BAX, caspase-3 mRNA increased (P < 0.05). Western blot indicated that BCL-2 protein expression also decreased (P < 0.05) and BAX, caspase-3 protein expression increased. It is concluded that the mitoxantrone can inhibit the proliferation of RPMI-8226 cells by inducing cell apoptosis. Activation of the mitochondrial and death receptor pathways of apoptosis may be involved in the mitoxantrone-induced apoptosis, the cell cycle arrest may also play an important role in the apoptosis mechanism.