Résumé
@# Objective: To investigate the effect of licorice on radio-sensitization of nasopharyngeal carcinoma CNE-2 cells and its mechanism. Methods: The radio-resistant nasopharyngeal carcinoma cell line (CNE-2-RR) was constructed and cultured in vitro. MTT assay was used to detect the effect of different concentrations of licorice on the proliferation activity of nasopharyngeal carcinoma cells. The changes of autophagosome in CNE-2-RR cells after licorice treatment were observed by transmission electron microscopy (TEM). Western blotting was used to detect the effect of licorice on the level of autophagy protein in CNE-2-RR cells. Single cell gel electrophoresis (comet assay) was used to detect the DNAdamage and repair of different groups of CNE-2-RR cells. Flow cytometry was used to detect the apoptosis rate of CNE-2-RR cell line. Results: Low-radiation resistant CNE-2-RR cell line was successfully constructed; MTT assay showed that 20 mmol/L licorice exhibited highest inhibition on CNE-2-RR cells (58.86 ± 5.02)%. Transmission electron microscopy showed increased autophagicbody and abnormal mitochondria and nuclei morphology in CNE-2-RR cells after treatment. Western blotting showed that autophagic protein LC3-II level was increased and LC3-I level was decreased in CNE-2-RR cells (P < 0.05). The results of single cell gel electrophoresis showed that the length of comet tail distance of CNE-2-RR cells after licorice treatment was higher than that of the control group (P<0.05), indicating weakened repair ability of DNA damage. Conclusion: Licorice enhances the radio-sensitivity of CNE-2-RR cells by influencing autophagy and DNArepair ability.