[Comparison of the Epstein-Barr virus infection and 30 bp-deleted LMP1 gene among 4 histologic types of nasopharyngeal carcinoma].
OBJECTIVE
To compare the Epstein-Barr virus (EBV) infection rates and the frequencies of wt-LMP1 and del-LMP1 EBV variants detected singly or dually among the four types of nasopharyngeal carcinoma (NPC) and to illustrate the possible role of del-LMP1 gene in nasopharyngeal carcinogenesis.


METHODS
EBER in situ hybridization was performed in 117 NPCs, including 48 non-keratinizing carcinomas (NKCs), 25 keratinizing squamous cell carcinomas (KSCCs), 5 adenosquamous carcinomas (ASCs), 6 mucoepidermoid carcinomas (MECs) and 33 adenocarcinomas (ACs). Nested PCR for demonstration of EBV LMP1 gene was performed on the tissue samples collected from 99 EBER-positive carcinoma cases and the peripheral blood mononuclear cells (PBMCs) of 53 healthy adults (HAs).


RESULTS
As indicated by EBER in-situ hybridization, the EBV infection rates in both of 48 NKCs and 25 KSCCs were 100%; and the infection rates of 11 ASCs/MECs and 33 ACs were 9/11 and 51.5% (17/33), respectively. Worthy to note was that most of the NKC cells were EBER-positive while only a small number of EBER-positive neoplastic cells could be found in 17 ACs. The percentage of del-LMP1 EBV variant detected singly in NKCs (85.4%, 41/48) was not only significantly higher than that in PBMCs of 46 HAs (8.7%, 4/46) but also significantly higher than those detected in KSCCs (16.0%, 4/25). The dual infection rate of wt-LMP1 and del-LMP1 variants detected in KSCCs (56.0%, 14/25) was significantly higher than that of NKCs (12.5%, 6/48). The majority of the EBV detected in AC tissues (12/17) and HAs' PBMCs (34/46, 73.7%) were of dual wt-LMP1 and del-LMP1 variants.


CONCLUSIONS
The EBV infection rates are significantly different among 3 major histological categories, namely, NKC/KSCC, ASC/MEC and AC. Though NKCs and KSCCs are always consistently associated with EBV, the single del-LMP1 EBV variant detected in NKCs is predominant over that in KSCCs and most of the KSCCs contain dual wt-LMP1 and del-LMP1 EBV variants. The EBV of the del-LMP1 variant might play a crucial role in carcinogenesis of NKC.
D000328:Adult; D020031:Epstein-Barr Virus Infections / Q000453:epidemiology*; D005260:Female; D017353:Gene Deletion; D006801:Humans; D008297:Male; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000209:etiology / Q000821:virology*; D014763:Viral Matrix Proteins / Q000235:genetics*
C037662:EBV-associated membrane antigen, Epstein-Barr virus; D014763:Viral Matrix Proteins