RESUMO
Cell cycle progression and apoptosis are controlled by regulatory proteins, including p53, of which functional alterations are linked to carcinogenesis. Recently, malignant mesothelioma (MM), a primary tumour related to asbestos exposure, alternatively to post therapeutic radiations, has proven to be an important problem in oncogenesis. The p53 protein does not seem mutated or deleted in MM but a possible inactivation by binding to other proteins [mdm2; SV40 large T antigen (Tag)] has been suggested. The present work investigated cell cycle regulation in normal rat pleural mesothelial cells (RPMC) and in RPMC expressing Tag (RPMC-TSV40), under exposure to asbestos and radiations. In RPMC, these agents induced activation of cell cycle checkpoints located at G1/S and G2/M and/or mitosis but a lack of control at G1/S was found in RPMC-TSV40. A loss of G2/M control may account for the formation of micronuclei observed after exposure of RPMC-TSV40 to radiations. In RPMC-TSV40 the enhancement of abnormal mitoses and apoptosis after asbestos exposure, in comparison with RPMC, suggests a loss of mitotic control and a p53-independent mechanism of apoptosis. Thus Tag expression in mesothelial cells might have both adverse and beneficial effects by impairing the control of DNA integrity and enhancing apoptosis respectively.
Assuntos
Antígenos Transformantes de Poliomavirus/fisiologia , Apoptose/fisiologia , Amianto/toxicidade , Carcinógenos/toxicidade , Ciclo Celular/fisiologia , Dano ao DNA , Raios gama/efeitos adversos , Pleura/citologia , Pleura/metabolismo , Animais , Antígenos Transformantes de Poliomavirus/biossíntese , Apoptose/efeitos dos fármacos , Apoptose/efeitos da radiação , Ciclo Celular/efeitos dos fármacos , Ciclo Celular/efeitos da radiação , Células Cultivadas , Aberrações Cromossômicas , DNA/efeitos dos fármacos , DNA/metabolismo , DNA/efeitos da radiação , Células Epiteliais/citologia , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/metabolismo , Pleura/efeitos dos fármacos , Proteínas Proto-Oncogênicas p21(ras)/biossíntese , Proteínas Proto-Oncogênicas p21(ras)/fisiologia , Ratos , Proteína Supressora de Tumor p53/biossíntese , Proteína Supressora de Tumor p53/fisiologiaRESUMO
An improved quantitative polymerase chain reaction (qPCR) method based on a combination of real-time detection and the 5'-3' nuclease activity of the Taq DNA polymerase was developed to quantify the provirus load of feline immunodeficiency virus (FIV), a lentivirus of veterinary importance and an animal model for AIDS research. Two fluorogenic probes were designed to detect FIV provirus in genomic DNA of peripheral lymphocytes and tissues infected with different FIV subtypes. The most sensitive assay can detect one copy of FIV provirus. The assay showed excellent precision within-run and between-runs. Comparison of the TaqMan system with a conventional seminested PCR assay revealed a comparable detection limit and good correlation. Furthermore the design of the two probes allowed the detection of various FIV isolates of clade A and B.