Molecular Mechanism Of Drug Resistance For Nasopharyngeal Carcinoma Cells After X-radiation

So far, surgical, drug, radiation and biological treatments have been adopted for tumor therapy. Generally, more than two ways are necessary to most cancer. In recent years, it has been found that resistance to drug after radiation for some tumors (nasopharyngeal carcinoma, lung cancer) emerges, which is the major impediment to successful treatment of many tumor typesAt present, it has been clarified that multidrug resistance of tumor occurs after chemotherapy, which involves many genes such as drug resistance genes, DNA repair gene. Because the targets of radiotherapy and chemotherapy are both DNA, moreover, lesioned DNA both need repair, it is supposed that multi-drug resistance of tumor after radiation is probably related to drug resistance genes and DNA repair system. In addition, it has been found that DNA repair system is not only associated with cellular sensitivity to chemotherapy, but also with cellular sensitivity to radiotherapy. This study was performed on basis of following considerations.Objective: To explore mechanisms of multi-drug resistance and DNA repair of tumor after radiation by studying the expression of drug resistance genes and DNA repair genes in nasopharyngeal carcinoma CNE cells after X-radiation and to establish theoretical basis for improvement effect of chemotherapy and radiotherapy of tumor.Methods: The CNE cells were exposed to 5 fractions of 10 Gy of X-radiation, once exposure daily. After the final exposure, the partial cells were harvested and the rest were allowed to repopulate in culture medium. Cells were harvested once a week and 5 times totally(0-4th weeks after...