All-trans retinoic acid inhibited the growth of human esophageal cancer EC9706 cells in nude mice

Objective:To investigate the anti-tumor effect of alltrans retinoic acid(ATRA) in vivo and its mechanisms.Methods:Human esophageal cancer EC9706 cells were transplanted into nude mice to establish the solid tumor model.We observed the tumor growth and calculated the tumor growth inhibition rate after administration of all-trans retinoic acid.Ten days after all-trans retinoic acid treatment,morphological changes of tumor tissues were examined by HE staining.Apoptosis was detected by TUNEL assay and the protein expression of apoptosis-associated gene bax and bcl-2 were tested by immunohistochemical method.Results:All-trans retinoic acid significantly inhibited the growth of human esophageal cancer EC9706 cells in nude mice,and the tumor growth inhibition rate was more than 60%.Histological examination and TUNEL staining revealed the scattered apoptotic cells and apoptotic bodies in tumor tissues.The protein expression of apoptosis-associated gene bax was increased and that of bcl-2 was decreased.Conclusion:All-trans retinoic acid has stronger anti-tumor effect in vivo.The mechanism of its anti-tumor effect might be mediated by inducing the apoptosis of tumor cells.