Expression Of P-glycoprotein Of Nasopharyngeal Carcinoma Cell And Its Influence To Radio-chemotherapy Sensitivity

OBJECTIVE: Acquisition of a multidrug resistance (MDR) phenotype in tumour cells is a major obstacle to successful therpy. One of the mechanisms involved in the development of MDR in human cells is the overexpression of P-glycoprotein (P-gp). Current researches suggest that P-gp is likely to play potential multiple physiological roles including influenting radio-chemotherapy sensitivity of tumor. Chinese, especially people living in south of China, have a high mobidity of nasopharyngeal carcinoma (NPC) relatively.70% of NPC patients are III or IV stage when they were diagnosed. Generally advanced NPC should be teated by radiotherapy combined with chemotherapy, but no evidence can confirm the order of radiotherapy and chemotherapy. Low differentiated squamous cell carcinoma is about 80-85% of NPC pathological types and well differentiated squamous cell carcinoma is 10%. In my experiment changes of expression and function of mdrl gene and P-gp of CNE1 cell (well differentiated squamous cell of NPC) and CNE2 cell (Low differentiated squamous cell of NPC) before and after treated by chemotherpeutic agents and irradiated by X-ray are assayed. Changes of radiotherapy sensitivity of the two kinds of cell lines after treated by chemotherpeutic agents are observed. Changes of chemotherapy sensitivity after irradiated are observed too. Moreover, difference of the two cell lines is compared. The experiment will help us go deep into comprehending the effection of P-gp to radio-chemotherapy sensitivity of NPC cells, especially different differentiated degree cells.The experiment provides us a new stratagem about radio-chemotherapy order in clinical therapy of NPC in different differebtiated degree.METHODS: Mdrl-mRNA of CNEl and CNE2 cell before arid after treated by chemotherapeutic agents and irradiated by X-ray was assayed by RT-PCR. Western blotting was used for expression of P-gp. Flow cytometry (FCM) was performed to examine the efflux function of cell to chemotherapeutic agents. Changes of radiotherapy sensitivity of cells treated by chemotherapy agents were analyzed by colony formation experiment.RESULTS: Expression of mdrl-mRNA and P-gp of CNEl and CNE2 cell almost in a long time after acted by Adriamycin (ADM) and irradiated by X-ray was found, but not before. Testing with FCM, we found that mean fluorescent intensity (MFI) of Daunorubicin (DNR) in CNEl cell treated by ADM increases a little, but the number of positive cell decreased obviously; the number of positive cell of CNEl irradiated remains steady, but MFI decreases. The number of positive cell of CNE2 treated by ADM increases and MFI decreased; the number of positive cell of CNE2 irradiated increased obviously and MFI increases a little. These indicate that the sensitivity of CNEl to DNR decreases after acted by ADM or irradiated; the sensitivity of CNE2 to DNR decreases after acted by ADM and increases after irradiated. CNE2 is more sensitive to DNR than CNEl either after treated by ADM or irradiated. After treated by ADM the radiotherapy sensitivity of CNEl increased and CNE2 decreased. The radiotherapy sensitivity of CNE2 is higher than CNEl.WNCLUTION: 1. CNE1 and CNE2 don't express mdrl gene and P-gp. 2. Mdrl gene and P-gp of CNEl and CNE2 cell express obviously almost in a long time after treated by chemotherapeutic agents or irradiated by X-ray. 3.The sensitivity of CNE2 is higher than CNEl to either chemotherapeutic agents or X-ray. 4.Radiative sensitivity of CNEl increased after treated by chemotherapeutic agents. 5.Radiative sensitivity of CNE2 decreased after treated by chemotherapeutic agents. 6.Chemotherapy sensitivity of CNEl decreased after irradiated by X-ray. 7. Chemotherapy sensitivity of CNE2 increased after irradiated by X-ray. 8. Chemotherapy before radiotherapy, namely induction chemotherapy (neoadjuvant chemotherapy), probably should be adopted in a combined therapy project to CNEl (well differentiated squamous cell of NPC). 9. Radiotherapy before chemotherapy, namely adjuvant chemotherapy, probably should be adopted in a combin...