RESUMO
BACKGROUND: The Epstein-Barr virus (EBV) encodes two anti-apoptotic cellular Bcl2 homologs, BALF1 and BHRF1. BHRF1 has an anti-apoptotic activity but is rarely expressed in nasopharyngeal carcinoma (NPC). However, BALF1 is not yet well characterized. OBJECTIVES: The objective of the study was to characterize BALF1 gene. First, the search of its transcriptional expression in EBV-positive B cell lines, EBV-positive Burkitt's lymphoma's cell lines and nasopharyngeal carcinoma's biopsies. Second, the examination of its anti-apoptotic activity in serum dependent assays. STUDY DESIGN: We first analysed the transcriptional expression of BALF1 by reverse transcriptase DNA polymerase chain reaction (RT-PCR) method. For the analysis of its anti-apoptotic activity, we transfected NIH3T3 cells with pBABE-BALF1 expression plasmid and studied serum dependence of these transfectants. RESULTS: BALF1 expression was detected in the latent stage and increased more significantly during the lytic phase in IgG-treated AKATA and TPA-SB-treated P3HR1-TK negative cell lines. As its expression was not affected by the inhibitor of viral DNA synthesis, this gene does not belong to late gene family. When analysed its transcription in Burkitt's lymphoma (BL)-derived cell lines and NPC biopsies, all BL-derived cell lines and more than 80% of NPC biopsies transcribed this gene. The study of serum dependence of BALF1-transfected NIH3T3 cells showed: with 10% of serum, BALF1 transfectants grew significantly more higher cell density than vector alone transfected NIH3T3 cell lines and with 1% of serum, BALF1 transfectants were capable of growing, but with about 40% reduced rate in comparison with those with 10% serum, while vector alone transfected NIH3T3 cells could not almost grow. CONCLUSION: BALF1 gene was transcribed in EBV-associated tumor cells. BALF1 could render cells to serum independent. These results suggest that BALF1 gene could play its role in EBV oncogenesis.
Assuntos
Linfoma de Burkitt/virologia , Herpesvirus Humano 4/genética , Neoplasias Nasofaríngeas/virologia , Transcrição Gênica , Proteínas Virais/genética , Células 3T3 , Animais , Biópsia , Linfoma de Burkitt/genética , Divisão Celular , Linhagem Celular Tumoral , DNA Complementar/genética , DNA Viral/genética , Herpesvirus Humano 4/crescimento & desenvolvimento , Humanos , Camundongos , Neoplasias Nasofaríngeas/genética , RNA Viral/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , TransfecçãoRESUMO
The association of Epstein-Barr virus (EBV) with Hodgkin's disease (HD) and non-Hodgkin's lymphoma (NHL) was examined in Algerian patients. The DNA extracted from fresh lymph node biopsies of 17 HD and five NHL was analysed by polymerase chain reaction (PCR). Fifteen out of 17 biopsies (88%) from HD contained EBV genome. Viral type analysis showed the coexistence of A and B types of EBV in 14 biopsies (93%), and the sole presence of A type virus in one biopsy. Among five NHL biopsies examined, four biopsies contained both A and B types of EBV, while one revealed A type-virus only. This co-infection of Algerian HD and NHL patients does not seem to be related with any histologic form of these diseases. The analysis of viral types in the saliva from 12 Algerian healthy individuals revealed six EBV positives with only one A type. Two types of lymphoma in Algeria therefore are closely associated with EBV, and are characterized by coinfection with A and B types of EBV.