OBJECTIVEMetformin (Met) can inhibit the proliferation of tumor cells in vitro, its effects on multiple myeloma and action mechanisms have been not yet understood. The purpose of this study was to investigate the effect and molecular mechanism of metformin on human myeloma cells U266.

METHODSU266 cells were treated with different concentration of Met, the MTT was used to detect cell proliferation, the PI staining was used to detect the cell cycle, and the protein expression of BCL-2 family and the release of cytochrome C were assessed by Western blot.

RESULTSMetformin could inhibit the proliferation of U266 cell in a time- and concentration- dependent manner. The U266 cells were arrested in G/G phase after metformin treatment for 48 h, as compared with non-treated U266 cells. The proteins expression of BCL-2 and BCL-XL was down-regulated and the protein expression of BAX was up-regulated. The released of cytochrome C from mitochondria to cytoplasm was increased, and protein splicing of PARP was also enhanced.

CONCLUSIONMetformin can inhibit the cell proliferation and induce U266 cell apoptosis through the mitochondrial apoptotic pathway.