Fig. 2.

TTP mediates the anti-proliferative function of metformin in both p53 wild-type and p53 mutant breast cancer cells. a–d Metformin inhibits proliferation of both p53 wild-type MCF7 cells and p53 mutant MDA-MB-231 cells. a, c MCF7 and b, d MDA-MB-231 cells were treated (a, b) with the indicated concentrations of metformin for 24 h and (c, d) with 6 mM metformin for 24 and 48 h. Cell viability was assessed by measuring absorbance at 490 nm using an MTS cell proliferation assay. The values obtained with mock-treated cells were set to 100. Values are the mean ± SD (n = 3). *p < 0.05, **p < 0.01, ***p < 0.001. e–h Inhibition of TTP attenuates the anti-proliferative effects of metformin in both MCF7 and MDA-MB-231 cells. MCF7 and MDA-MB-231 cells were transfected with e, g, h pcDNA6/TTP or f, g, h TTP-specific siRNA (TTP-siRNA). scRNA and pcDNA6 were used as negative controls. After treatment with 6 mM metformin for 24 h, cell viability was assessed by measuring the absorbance at 490 nm using an MTS cell proliferation assay. The values obtained with mock-treated cells were set to 100. Values are the mean ± SD (n = 3). *p < 0.05, **p < 0.01, ***p < 0.001. ns not significant