The Radiation Sensitizing Enhancement Effect Of Gemcitabine In Human Nasopharyngeal Carcinaoma Cell Line (CNE-2)

Objective To analyse the radiation sensitizing enhancement effect and its mechanism of gemcitabine in human nasopharyngeal carcinaoma cell line(CNE-2) in vitro. Methods Flow cytometry was used to observe the cell-cycle effect of Y -ray irradiation with gemcitabine on CNE-2 cell line. The effect of radiosensitivity was determined by clonogenic assay and was quantified by calculating the sensitive enhancement ratio (SER). Results Irradiation resulted in GI block in a dose-dependent (<6Gy) manner. Concentrations of 5 mg /L, 10 mg /L, 15 mg /L gemcitabine incubated with CNE-2 for 24h prior to 2 Gy irradiation, which showed significantly phase-S block while phase GI block was observed following the increasing doses of irradiation. 15nmol/L gemcitabine incubated with CNE-2 for 12h prior to 2 Gy irradiation, which showed significantly phase-Gi block at the beginning while phase-S block was observed after 24h and lasting at least for 36 h. Gemcitabine resulted in a radiosensitization in CNE-2 cells, SER was 1.02, 1.30 and 1.37 respectively for 5 mg /L, 15 mg /L and 20 mg /L gemcitabine. Conclutions Radiosensitization of gemcitabine in CNE-2 cells is associated with its induction of phase-S or phase GI block and its reduction of the repair of damaged DNA. The appropriate radiation-sensitizing concentrations of gemcitabine in vitro was 15 mg /L to 20 mg /L.