p53 overexpression is different in Epstein-Barr virus-associated and Epstein-Barr virus-negative carcinoma.
OBJECTIVE
Epstein-Barr virus (EBV) is associated with a subset of gastric and head and neck carcinomas. While p53 mutation and overexpression is common in gastric cancer, in nasopharyngeal carcinoma p53 is overexpressed yet mutation is uncommon, leading to a proposed viral mechanism of p53 upregulation. We examined the expression of p53 protein in 18 EBV-associated gastric carcinomas (EBV-GA) and compared it with 29 age and sex matched EBV-negative gastric carcinomas (EBV0-GA) and 23 non-nasopharyngeal EBV-associated carcinomas (EBV-CAs) arising from various head and neck regions.


RESULTS
Using two monoclonal antibodies (DO7 and PAb1801) with microwave pre-treatment, the p53 protein was scored according to the intensity and percentage of positive cells. The EBV0-GA showed a clear cut bimodal distribution of p53 levels, with either homogeneous intense staining of most tumour nuclei, or only very weak expression in a few cells. Nearly all the EBV-GA and EBV-CAs showed a weak to moderate p53 expression, characterized by heterogeneous intensity of staining in a variable proportion of tumour cells.


CONCLUSIONS
The difference in p53 levels in the EBV0-GA and EBV-GA is statistically significant. The heterogeneous level of p53 in the EBV-GA and EBV-CAs and its difference from the EBV0-GA is suggestive of a non-mutational mechanism of p53 upregulation and underscores the role of the virus in the oncogenic pathway.
Leung
S Y
SY
Department of Pathology, University of Hong Kong, Queen Mary Hospital, Hong Kong.
Chau
K Y
KY
Yuen
S T
ST
Chu
K M
KM
Branicki
F J
FJ
Chung
L P
LP
D002277:Carcinoma / Q000378:metabolism* / Q000821:virology*; D005260:Female; D006258:Head and Neck Neoplasms / Q000378:metabolism* / Q000821:virology; D004854:Herpesvirus 4, Human / Q000302:isolation & purification*; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008297:Male; D008875:Middle Aged; D013274:Stomach Neoplasms / Q000378:metabolism* / Q000821:virology; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
D016159:Tumor Suppressor Protein p53