EPSTEIN-BARR-VIRUS EXPRESSION WITHIN KERATINIZING NASOPHARYNGEAL CARCINOMA

Three stages of maturation can be seen in keratinizing nasopharyngeal carcinomas. These stages are similar morphologically to basal cells, i ntermediate and superficial squamous cells seen in normal squamous epi thelium. Taking advantage of such a diverse tumour cell population, 10 keratinizing nasopharyngeal carcinoma (NPC) were examined by in situ hybridization for the presence of latent Epstein-Barr Virus (EBV) usin g EBV encoded RNAs (EBERs) and by immunohistology for the presence of EBV early antigen-diffuse (EA-D) and the 350/220 kd membrane glycoprot ein of the EBV. The basal cell-like tumour cells are mainly infected l atently with the virus; viral replication was found in isolated interm ediate squamous cells, whilst superficial squamous cells are largely d epleted of all the viral markers. We used a control series of non-kera tinizing nasopharyngeal carcinomas composed of undifferentiated and po orly differentiated tumour cells and EBV latency was present in these tumours. Viral replication was detected by RT-PCR, in the undifferenti ated tumours but viral replication was not seen by immunohistology. Th e possible relationship between EBV life cycle in these tumours and tu mour cell differentiation is discussed in the light of these findings. (C) 1998 Wiley-Liss, Inc.