Expression of multidrug resistance 1 and glutathione-S-transferase-pi protein in nasopharyngeal carcinoma

Radiotherapy is the modality of choice for the treatment of nasopharyngeal carcinoma (NPC): However, systemic chemotherapy has recently been found to play an increasing role in the treatment of advanced or metastatic disease. The status of drug resistance gene expression that has crucial impact on c hemotherapy has not been fully addressed for patients with NPC. In this stu dy, we examined the expression of multidrug resistance 1 (MDR-1) and glutat hione-S-transferase-pi (GST-pi) in primary, recurrent, and metastatic NPC u sing results of immunohistochemical examinations. The results were correlat ed with the expression of Epstein-Barr virus (EBV) latent protein, latent m embrane protein 1 (LMP1), and clinicopathologic features, including stage, histopathologic types, and survival rates. MDR-1 protein expression was det ected in 18 (12.6%) of 143 patients with primary NPC, 14 (32.6%) of 43 with recurrent NPC, and O (0%) of 20 with metastatic NPC, whereas 83 (58%) of 1 43 patients with primary NPC, 30 (69.8%) of 43 with recurrent NPC, and 13 ( 65%) of 20 with metastatic NPC expressed GST-pi. EBV-LMP1 was expressed in 59 (41.3%) of 143 patients with primary NPC, 23 (53.5%) of 43 with recurren t NPC, and 9 (45%) of 20 with metastatic NPC. Simultaneous expression of MD R1 and GST-pi was observed in 13 (72.2%) of 18 patients with primary NPC an d 12 (85.7%) of 14 with recurrent NPC. The expression of LMP1 was detected in only 6 of the 13 patients with primary NPC and 6 of the 12 with recurren t NPC. We concluded that the expression of GST-pi was more frequent in NPC tumor tissues than the expression of MDR-1. The expression of MDR-1 correla ted with clinicopathologic features of primary NPC, including the histopath ologic types and survival rates, but not with disease stage. The expression of GST-pi did not correlate with clinicopathologic features. The expressio n of MDR-I and GST-ir did not correlate with expression of EBV-LMP1 for pat ients with NPC. Hum PATHOL 32:1240-1244. Copyright (C) 2001 by W.B. Saunder s Company.