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. Theprimary purpose of this paper was to define the effects of β-carotene and 1,25-dihydroxyvitamin D3, alone and incombination, on cell proliferation, cell cycle and apoptosis of human esophageal cancer EC9706 cells. Treatmentwith different concentrations of β-carotene and/or 1,25-dihydroxyvitamin D3. MTT assay showed that β-caroteneand 1,25-dihydroxyvitamin D3 significantly inhibited proliferation of EC9706 cells in a dose- and time-dependentmanner. Further studies also demonstrated that β-carotene alone or 1,25-dihydroxyvitamin D3 alone caused amarked increase on the induction of apoptosis in EC9706 cells. The percentage of G0/G1-phase cells significantlyincreased on addition of 1,25-dihydroxyvitamin D3 alone, but there were no significant changes with β-carotenealone. These two agents in combination synergistically inhibited cell growth and induced apoptosis. Therefore,our results indicate that β-carotene and 1,25-dihydroxyvitamin D3 in combination may provide a novel strategyfor preventing and treating esophageal cancer.