OBJECTIVETo investigate the effect of bortezomib (Bor) alone or in combination with As(2)O(3) (ATO) and/or dexamethasone (DXM) on proliferation and apoptosis in KM3 human multiple myeloma cell line KM3.

METHODSKM3 cells were cultured with different concentrations of Bor and ATO and/or DXM in combination or Bor, ATO, DXM alone for different times. Cell proliferation was assayed by MTT assay, and IC(50) was calculated. Cell morphology was observed with light and electric microscopy. The agarose gel electrophoresis was used to evaluate DNA content, and the flow cytometry was used to exam Annexin V-FITC/PI stain.

RESULTSBor, ATO and DXM inhibited KM3 cell proliferation in a time-and dose-dependent manner with the IC(50) of 0.27, 3.10 and 8.01 micromol/L, respectively. The inhibition rate of KM3 cells by Bor plus ATO and DXM was significantly higher than Bor plus ATO or DXM \[(34.51 +/- 0.51)% vs (25.39 +/- 0.90)% and (34.51 +/- 0.51)% vs (23.80 +/- 0.78)% respectively\]. Typical morphology for apoptosis and DNA ladder were observed in KM3 cell treated with 0.25 micromol/L Bor for 48 h, by Annexin V positivity. The apoptosis rate induced by Bor plus both ATO and DXM was higher than that induced by Bor plus DXM.

CONCLUSIONBor can inhibit the proliferation and induce apoptosis of KM3 cells. Bor enhances the inhibitory effect of ATO and DXM on the growth of KM3 cell. ATO enhances the apoptosis effects of Bor and DXM on KM3 cells.