Objective To investigate the radiosensitiation effect of berberine on human nasopharyngeal carcinoma ( NPC) in hypoxia condition and explore the underlying mechanisms. Methods MTT assay, clonogenic assay and flow cytometry were performed to analyze cell proliferation, colony formation and apoptosis, respectively. Male nude mice inoculated subcutaneously with CNE-2 cells were used to examine the radiosensitization effect of berberine in vivo. The expressions of HIF-1α and VEGF were assessed by Western blot. Results Berberine efficiently inhibited the proliferation of CNE-2 cells in time-dependent and dose-dependent fashions with an IC50 of ( 14?9 ± 2?2 ) μmol/L. Clonogenic survival assay showed that berberine ( 5 μmol/L ) sensitized CNE-2 cells to ionizing radiation in hypoxia and its SERD0 was 1?27. Under hypoxic condition, berberine alone (5, 15 μmol/L) could induce apoptosis (t=5?01, 9?02,P<0?05) and it further promoted 8 Gy radiation-induced apoptosis (t =5?31, 9?91,P <0?05). Moreover, berberine significantly delayed the tumor growth in the combination group (berberine +irradiation) compared with the mice received irradiation alone or PBS (t =2?96, 14?52, P <0?05). Immunobloting assay showed that berberine inhibited the upregulation of HIF-1α and VEGF induced by hypoxia in CNE-2 cells. Conclusion Berberine confers radiosensitivity on hypoxic NPC in vitro and in vivo, which is probably associated with the downregulation of HIF-1α and VEGF expressions.

Objective To explore the radiosensitivity of berberine on esophageal cancer cells under hypoxia condition.Methods MTT assay and clonogenic survival assay were used to evaluate the effect of berberine on proliferation inhibition and radiosensitivity of esophageal cancer cells,respectively.Immunofluorescence was employed to examine the expression of HIF-1.The change of cell cycle distribution and cell apoptosis was assayed by flow cytometry.The expression of HIF-1 was measured by Western blot.DNA damage was detected by γ-H2AX Foci counting.Results With a clear dose and time effect,berberine inhibited cell proliferation and enhanced cell radiosensitivity(t =3.69,P＜0.05)with a sensitizing enhancement ratio(SER)of 1.42.Berberine caused a dose-dependent decrease in HIF-1 protein expression and also significantly increased the cell apoptosis in ECA-109 population(t=4.74,P＜0.05).Compared with the radiation alone group,berberine enhanced X-ray induced DNA double chain breaks(DSB).Conclusions Berberine can increase the radiosensitivity of esophageal cell line ECA-109,which may be associated with decrease of HIF-1 expression and induction of apoptosis in ECA-109 cells.