RESUMEN
<p><b>OBJECTIVE</b>To study the effect and mechanism of tetrandrine (Tet) on enhancing radiosensitivity of human nasopharyngeal carcinoma cell lines in vitro.</p><p><b>METHODS</b>CNE1 and CNE2 were exposed to radiation with or without Tet, the DNA damage of the cells were evaluated by neutral comet electrophoresis, and cell cycle and apoptosis were analyzed by flow cytometry.</p><p><b>RESULTS</b>The mean tail movements (TM) of CNE1 treated with radiation or radiation plus Tet were (7.13 ± 3.70) (X(-) ± s) and (13.61 ± 5.45), respectively (t = 2.784, P < 0.05), and TM of CNE2 treated with radiation or radiation plus Tet were (11.52 ± 4.04) and (18.85 ± 6.18), respectively (t = 3.089, P < 0.05). With the exposure to radiation or radiation plus Tet, the percentages of CNE1 in G2 phases were (42.62 ± 2.07)% and (17.02 ± 1.87)%, respectively (t = 23.173, P < 0.01), and the percentages of CNE2 in G2 phases were (34.82 ± 2.74)% and (19.64 ± 4.82)%, respectively(t = 16.500, P < 0.01). There was no significant difference in the apoptosis rates between the cells treated with radiation or radiation plus Tet regardless of CNE1 (17.24 ± 0.99)% vs (19.11 ± 1.24)%, and CNE2 (16.68 ± 0.27)% vs (18.51 ± 2.41)% (P > 0.05).</p><p><b>CONCLUSIONS</b>Tet can enhance radiosensitivity of human nasopharyngeal carcinoma cell lines. The mechanism could be related to abrogation of radiation-induced G2/M arrest and reduction of double-strand break repair capacity.</p>