[Expression of multidrug resistance gene in nasopharyngeal carcinoma cells after irradiation exposure]

To examine the changes in the function and expression of multidrug resistance gene (mdr1) and P-gly-coprotein (P-gp) in nasopharyngeal carcinoma (NPC) CNE1 cell following irradiation for determining the sequential order of radiotherapy and chemotherapy in the treatment of NPC.The expressions of mdr1 gene and its protein P-gp as well as the function of P-gp efflux were examined in CNE1 cells before and after irradiation exposure by reverse transcriptional polymerase chain reaction (RT-PCR), Western blotting and flow cytometry, respectively.Irradiation of CNE1 cells induced a long-term overexpression of mdr1 gene and P-gp and reduction in intracellular daunorubicin accumulation.Irradiation decreases the chemotherapy sensitivity of CNE1 cell, and induction chemotherapy should be therefore performed before radiotherapy in the treatment of advanced NPC.