Low concentrations of metformin selectively inhibited the proliferation of CD133⁺ pancreatic cancer cells.

<p>A, Growth curves for pancreatic cancer cells treated with low concentrations of metformin. AsPC-1 and SW1990 cells were incubated with 0.2 mM or 0.1 mM metformin, respectively, and their numbers counted at each time point. The results are presented as the fold increase relative to 0 h. B, Effect of low concentrations of metformin on the proportion of CD133⁺ cells. AsPC-1 and SW1990 cells were incubated with 0.2 mM or 0.1 mM metformin, respectively, and the proportion of CD133⁺ cells was determined at each time point. The proportion of CD133⁺ cells decreased gradually. C, Growth curves for CD133⁺ and CD133^– pancreatic cancer cells treated with low concentrations of metformin. The total number of pancreatic cancer cells and the proportions of CD133⁺ and CD133^– cells were determined at each time point. The results are presented as the fold increase relative to 0 h. The proliferation of CD133⁺ cells was selectively inhibited. Error bars represent the standard deviation.