Inhibition of Proliferation and Induction of Apoptosis by the Combination of β-carotene and 1,25-dihydroxyvitamin D3 in Human Esophageal Cancer EC9706 Cells

Esophageal cancer is a common malignant tumor occurring in human esophageal epithelial tissue. The primary purpose of this paper was to define the effects of beta-carotene and 1,25-dihydroxyvitamin D-3, alone and in combination, on cell proliferation, cell cycle and apoptosis of human esophageal cancer EC9706 cells. Treatment with different concentrations of beta-carotene and/or 1,25-dihydroxyvitamin D-3. MTT assay showed that beta-carotene and 1,25-dihydroxyvitamin D-3 significantly inhibited proliferation of EC9706 cells in a dose-and time-dependent manner. Further studies also demonstrated that beta-carotene alone or 1,25-dihydroxyvitamin D-3 alone caused a marked increase on the induction of apoptosis in EC9706 cells. The percentage of G0/G1-phase cells significantly increased on addition of 1,25-dihydroxyvitamin D-3 alone, but there were no significant changes with beta-carotene alone. These two agents in combination synergistically inhibited cell growth and induced apoptosis. Therefore, our results indicate that beta-carotene and 1,25-dihydroxyvitamin D-3 in combination may provide a novel strategy for preventing and treating esophageal cancer.