Effects of leptin on colorectal cancer cell line HT-29

The purpose of this study was to investigate the effect of leptin on the growth of HT-29 colorectal cancer cell line. HT-29 cells were treated with leptin at several concentrations of 0, 5, 50, 100, 200 ng/ml, respectively. Epidermal growth factor (EGF) was taken as the positive control. The effect of leptin on the growth, proliferation and apoptosis of HT-29 colorectal cancer cell line was assayed through drawing growth curve and by the MTT [3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide] method and flow cytometry (FCM). According to the growth curve, the cell counts of HT-29 cell line increased in proportion to leptin concentration, varying from 5 to 200 ng/ml at a dose-dependent manner. However, the cell proliferation amounts of 200 ng/ml leptin group were still less than those of the positive control group (EGF). The MTT results were similar to those from cell counting method. Leptin at different concentration levels promoted the growth of HT-29 cell lines in a time- and dose-dependent manner, and the proliferation rate varied from 5.1 to 67.9%. FCM analysis showed that leptin can significantly affect cell cycle of HT-29 cells. With increasing concentrations, G0/G1 phase cells decreased gradually, and S and G2/M phase cells rose gradually, but no significant effect of leptin on apoptosis of HT-29 cells was observed. In vitro, leptin could promote growth and proliferation of HT-29 cell line according to the concentration and experimental time, but there was no significant correlation in apoptosis