Effects Of EGCG On Multiple Myeloma Cell Line In Vitro

PartⅠThe inhibitory effect of EGCG on the proliferation and activity of proteasome in multiple myeloma KM3 cell line【Objective】To investigate the effect of (-)-epigallocatechin-3- gallate (EGCG) on the proliferation and activity of proteasome in multiple myeloma KM3 cell line.【Methods】The multiple myeloma cells were cultured in vitro. KM3 cells were treated with EGCG at various concentrations for different periods, and MTT assays were used to measure the proliferative activity. After cultured with EGCG, the proteasome activity of cells were examined. The enzyme activity was indicated by fluorescence absorbance(A) produced by degradation of specific substrates by proteasome.【Results】EGCG can obviously inhibit the growth and proliferation of the KM3 cells, which showed a dose and time dependent relationship between 5 and 100μmol/L concentrations. After treated with EGCG for 48 hours, the inbitory rates of various concentrations were in excess of 20%. The proteasome activity of KM3 cells decreased with the increment of concentrations while treated for a same period. The inhibitory rate was 78.5±4.46% when the concentration of EGCG wan 100μmol/L, which were significantly less than the control(P<0.01). 【Conclusion】EGCG can greatly inhibit the proliferation of multiple myeloma KM3 cell line, and can also inhibit the proteasome activity of KM3 cells in a dose dependent manner. PartⅡEGCG inhibits angiogenesis induced by multiple myeloma KM3 cell line【Objective】To investigate the effect of (-)-epigallocatechin-3- gallate (EGCG) on angiogenesis induced by multiple myeloma cells and the mechanisms of it.【Methods】Endothelial cell migration assay and tubule formation assay were applied to assay the angiogenic activity. The expression level of vascular endothelial growth factor (VEGF) in KM3 cells supernatant and VEGF mRNA were detected by ELISA and RT-PCR, respectively.【Results】The KM3 cells supernatant significantly induced endothelial cell migration and tubule formation in vitro. EGCG inhibited the effect of endothelial cell migration induced by KM3 cells supernatant, and the numbers of migrated cells were 414±27 at 5μmol/L, 299±70 at 25μmol/L, 202±42 at 50μmol/L, 116±13 at 100μmol/L.The numbers of migrated cells showed negative correlation with the dose of EGCG(r=-0.952, p<0.05). The areas of the capillary-like structures decreased while the concentrations of EGCG increased, 0.088±0.003mm2 at 25μmol/L, 0.061±0.001mm2 at 50μmol/L , which were significantly less than the control(p<0.01)and showed negative correlation with the dose of EGCG(r=-0.888, p<0.05). 48 hours after treatment of EGCG at concentrations of 5, 25, 50 and 100μmol/L , the levels of VEGF in the supernatant were 1399.0±47.4,660.1±5.7,108.5±5.8 and 26.2±18.6pg/ml, respectively. Except 5μmol/L, all the other groups showed significant changes while compared with the controls (p<0.01). Furthermore, EGCG depressed the mRNA expression of VEGF in KM3 cells in a dose-dependent manner.【Conclusion】 EGCG can significantly inhibit angiogenic ability of multiple myeloma KM3 cells, which is in part due to downregulation of mRNA expression and secretion of VEGF. Therefore, EGCG could serve as a novel drug to treat multiple myeloma.