Effects of all-trans retinoic acid on proliferation, cell cycle and apoptosis of human esophageal squamous cancer EC1 cells

Objective: To investigate the effects of ATRA (all-trans retinoic acid) on cell proliferation, cell cycle and apoptosis of human esophageal squamous cancer EC1 cells, and to explore its possible mechanism. Methods: The abilities of cellular proliferation of EC1 cells after treatment with 1, 10 and 20 μmol/L ATRA were detected by MTT assay, and the cell cycle distribution and the apoptosis of EC1 cells were determined by flow cytometry. The expressions of p21 and Bcl-2 in EC1 cells after treatment with 1, 10 and 20 μmol/L ATRA were detected by immunocytochemistry and Western blotting. Results: As compared with the EC1 cells without treatment (as a control), the proliferation of EC1 cells was inhibited by ATRA in a dose- and time-dependent manner (P < 0.05). The proportions of G0 and G1 cells were higher in EC1 cells after treatment with 1, 10 and 20 μmol/L ATRA than that of the control cells [(66.58±0.30)%, (67.96±0.77)% and (75.11±2.24)% vs (59.90±0.82)%, P < 0.05]. The apoptotic rates of EC1 cells treated with 1, 10 and 20 μmol/L ATRA were higher than that of the control cells [(4.86±0.04)%, (7.35±0.04)% and (12.03±0.12)% vs (3.17±0.05)%, P < 0.05]. The expression level of p21 in EC1 cells treated with ATRA was up-regulated, but the expression level of Bcl-2 was down-regulated. Conclusion: ATRA can inhibit the proliferation of human esophageal squamous cancer EC1 cells and induce G0/G1 phase blocking and cell apoptosis. This effect may be related with the up-regulation of p21 expression and down-regulation of Bcl-2 expression. DOI:10.3781/j.issn.1000-7431.2013.08.005