In vitro growth inhibition of human colonic tumor cells by Verapamil

AIM: To investigate the effects and mechanisms of Verapamil on cultured human colonic tumor (HCT) cells. METHODS: HCT cells were treated with different concentrations of Verapamil, and their proliferation was examined by MTT assay. The areas of sub-diploid peak were measured by flow cytometry, and the DNA ladder was found by agarose gel electrophoresis. The characteristic changes in morphology were observed under light microscopy. The cell nuclei (propidium iodide labeled, PI-labeled) and cellular distribution and concentration of calcium (Fluo-3-labeled) were studied by using laser confocal scanning microscope. RESULTS: The proliferation of HCT cells was inhibited by different concentrations of Verapamil. With the increase in concentration of Verapamil, the percent of G0-G1 phase cells in HCT cells increased and that of S phase cells decreased. After treating with different concentrations of Verapamil, flow cytometry showed that HCT cells were enlarged in areas of sub-diploid in a dose-dependent manner. Gel electrophoresis results displayed a typical DNA ladder. On staining with Wrights-Giemsa, the typical cellular apoptosis morphologic changes were also observed. PI-labeled cell nuclei were found markedly changed. In addition, we inspected that the 100 mu mol/L Verapamil could increase the intracellular calcium ion concentration [Ca2+](i) in HCT cells. CONCLUSION: Verapamil can inhibit proliferation of HCT cells via inducing cell apoptosis. (C) 2005 The WJG Press and Elsevier Inc. All rights reserved.