RESUMO
<p><b>OBJECTIVE</b>To observe the effect of metformin on the proliferation of SW-480 cells and study the possible mechanism.</p><p><b>METHODS</b>The proliferation of SW-480 cells treated with different concentrations of metformin was assessed by MTT assay, and the cell cycle changes were analyzed by flow cytometry. The expression of cyclin D1 in the treated cells was detected by Western blotting, and telomerase activity examined by telomeric repeat amplification protocol (TRAP) silver staining.</p><p><b>RESULTS</b>Metformin decreased the proliferation of SW-480 cells in a dose- and time-dependent manner. The proportion of the cells at G0/G1 stage in the control and metformin-treated (5 mmol/L, 72 h) cells was (55.81-/+0.63)% and (63.38-/+0.99)%, the cell proportion at S stage was (31.11-/+3.05)% and (25.29-/+1.64)%, and that at G2/M stage was (13.09-/+3.00)% and (11.33-/+2.60)%, respectively. The expression of cyclin D1 in metformin-treated cells were lowered significantly as compared with that in the control cells. Telomerase activity was also decreased significantly in the cells after treatment with 5 mmol/L metformin for 72 h.</p><p><b>CONCLUSION</b>Metformin can inhibit the growth of SW-480 cells mainly by blocking the cell cycle at G0/G1, down-regulating the expression of cyclin D1 and decreasing telomerase activity.</p>