Similar BCL-X but different BCL-2 levels in the two age groups of north African nasopharyngeal carcinomas.
Nasopharyngeal carcinomas (NPCs) are consistently associated with the Epstein-Barr virus (EBV). As Bcl-2 and Bcl-X are co-expressed in EBV-transformed B-lymphocytes, we attempted to determine their status in malignant NPC cells. A retrospective series of 100 NPC specimens from untreated Tunisian patients was investigated by immuno-histochemistry. Twenty seven of the patients were below 30 years old and therefore classified in the "juvenile" form of north African NPCs. Bcl-2 and Bcl-X expression was assessed semi-quantitatively using a score based on the percentage of positive cells and staining intensity. Intense Bcl-X expression was detected in malignant cells of 100% biopsy samples with similar scores for patients below 30 years or those aged 30 or over. Bcl-2 was detected in 89% biopsies but its expression differed considerably between the samples. The average Bcl-2 score was much lower for patients under 30 years (4.4+/-1.5 compared to 6.5+/-2 for older patients; P<10(-6)). Multivariate analysis demonstrated that no other clinical parameter, except the primary tumor size, was correlated to the Bcl-2 score. Bcl-X and Bcl-2 are co-expressed in 89% of NPCs whereas their expression is mutually exclusive in other head and neck carcinomas (particularly squamous cell carcinomas, SCC). The constantly high expression of Bcl-X is consistent with it being induced by the EBV protein Epstein-Barr nuclear antigen 1 (EBNA1), as recently reported in a murine model. The contrasted levels of Bcl-2 expression in the two age groups strengthen the hypothesis that these clinical forms result from distinct oncogenic mechanisms.
Khabir
Abdelmajid
A
Laboratoire d'Anatomie et de Cytologie Pathologiques, Hôpital Universitaire Habib Bourguiba, 3029 Sfax, Tunisia.
Ghorbel
Abdelmoneem
A
Daoud
Jamel
J
Frikha
Mounir
M
Drira
Mohamed Mokhtar
MM
Laplanche
Agnès
A
Busson
Pierre
P
Jlidi
Rachid
R
D000293:Adolescent; D000328:Adult; D000349:Africa / Q000453:epidemiology; D017668:Age of Onset; D000368:Aged; D002277:Carcinoma / Q000453:epidemiology / Q000235:genetics* / Q000473:pathology; D002648:Child; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D019254:Genes, bcl-2; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000453:epidemiology / Q000235:genetics* / Q000473:pathology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000032:analysis* / Q000096:biosynthesis; D051020:bcl-X Protein
C494811:BCL2L1 protein, human; D019253:Proto-Oncogene Proteins c-bcl-2; D051020:bcl-X Protein