Ethnic differences in the expression of Epstein-Barr virus latent membraneprotein-1 mutations in nasopharyngeal carcinoma

The latent membrane protein-1 (LMP1) of Epstein-Barr virus (EBV) is a viral oncoprotein implicated in several EBV-associated pathologies. Many studies have characterized carboxy-terminal mutations within LMP1, errors in this area are critical since this portion contains sequences responsible for LMP 1 targeting, half-life and association with host cell proteins. Although, d ata suggests that mutations in this area extend LMP1 half-life and increase its oncogenesis, some studies have not shown this to be true for all EBV-a ssociated tumors. In order to evaluate 3'-end LMP1-DNA mutations in three d ifferent ethnic populations with nasopharyngeal carcinoma (NPC), we examine d EBV-DNA in 34 patients of various origins (Caucasian, Chinese and Inuit). While 68% of the total group expressed EBV-antigens, only 56% of Caucasian s but 86% of Inuit expressed this viral protein. Over 67% of Inuit NPC tiss ue contained the characteristic 30 bp deletion that was observed in only 20 % of Caucasians and 33% of Chinese samples. DNA sequencing revealed that th e Inuit population showed the most frequent DNA mutations and corresponding amino acid alterations in LMP1. Our results suggest that EBV-associated NP C-DNA mutations in LMP1 do not occur at equal rates in different racial gro ups and are more common at distinct sites in NPC tissue from Chinese and In uit sources. (C) 2000 Elsevier Science B.V. All rights reserved.