[Effects of Triptolide on MMP-9 Expression and Inducing Apoptosis of Multiple Myeloma Cells by Inhibiting SMYD3].

ABSTRACT

OBJECTIVE: To investigate the effect of triptolide(TPL) on proliferation and apoptosis of RPMI8226 cells and its mechanism. METHODS: MTT assay was used to measure the proliferation of RPMI8226 cells after treatment with different concentration (10, 20, 40, 80 and 160 nmol/L) of TPL for different incubation time (24 h, 48 h and 72 h). The cell apoptosis was detected by flow cytometry, the mRNA expressions of SMYD3 and MMP-9 were measured by quantitative real-time PCR, the protein level of H3K4me2 and H3K4me3 in RPMI8226 cells was assayed by Western blot. RESULTS: TPL inhibited RPMI8226 cell proliferation, and the inhibitory rate of cell proliferation increased significantly in a dose- and time-dependent manner(P<0.05), the RPMI8226 cell apoptosis was induced by treatment with 40, 80 and 160 nmol/L TPL (P<0.05), the qRT-PCR showed that treatment of RPMI8226 cells with TPL down-regulated the mRNA expression of SMYD3 in a dose-dependent manner(P<0.05). Compared with the blank group, the mRNA expression level of MMP-9 in RPMI8226 cells transfected by siRNA-SMYD3 was significantly depressed. Western blot showed that the protein levels of H3K4me2 and H3K4me3 were decreased in a dose-dependent manner after TPL treatment(P<0.05). Compared with the blank group and siRNA negative group, the protein level of H3K4me2 and H3K4me3 in RPMI8226 cells transfected by siRNA-SMYD3 also were significantly depressed(P<0.05). CONCLUSION: TPL can significantly inhibit the proliferation of RPMI8226 cells and induce their apoptosis, which may be related to the inhibition of SMYD3 expression by TPL- down-regulating the H3K4 methylation and the activating the MMP-9 transcription.