RESUMO
The ERBB2 gene is overexpressed in 30% of breast cancers and this has been correlated with poor prognosis. ERBB2 is upregulated in other cancers such as prostate, pancreas, colon and ovary. In breast cancer cells, the mechanisms leading to ERBB2 gene overexpression are increased transcription and gene amplification. In these cancers, AP-2 transcription factors are involved in ERBB2 overexpression, and AP-2 levels are correlated with p185(c-)(erbB-2) levels. In this work, we wanted to know if the same molecular mechanisms are responsible for the ERBB2 upregulation in non-breast cancers. We compared ERBB2 gene copy number, p185(c-)(erbB-2) and mRNA levels with AP-2 levels in several ovary, prostate, colon and pancreas cancer cells. A moderate expression of erbB-2 mRNA and protein were observed in some cells without gene amplification. In contrast to breast cancer cells, AP-2 factors were absent or low in some non-breast cells which did express ERBB2. It is thus likely that AP-2 is not a major player in the increased levels of erbB-2 transcripts in non-breast cancer cells. The transcriptional activity of the ERBB2 promoter in colon and ovary cancer cells was estimated using reporter vectors. The results showed that the promoter regions involved in ERBB2 gene overexpression in breast cancer cells are different from those that lead to the gene upregulation in colon and ovary cancers. In conclusion, our results indicate that different transcriptional and post-transcriptional mechanisms are responsible for the increased levels of erbB-2 transcript and protein in breast and non-breast cancer cells.
Assuntos
Neoplasias da Mama/genética , Amplificação de Genes , Genes erbB-2/fisiologia , Western Blotting , Proteínas de Ligação a DNA/biossíntese , Feminino , Dosagem de Genes , Regulação Neoplásica da Expressão Gênica , Humanos , Imuno-Histoquímica , Masculino , Neoplasias Ovarianas/genética , Neoplasias Pancreáticas/genética , Neoplasias da Próstata/genética , RNA Mensageiro/análise , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Fator de Transcrição AP-2 , Fatores de Transcrição/biossíntese , Transcrição Gênica , Transfecção , Células Tumorais Cultivadas , Regulação para CimaRESUMO
Gene transfer into the arterial wall may allow study of the role of specific genes in vascular pathophysiology and development of local gene therapies for vascular disorders. The feasibility of adeno-associated virus (AAV)-mediated gene transfer into isolated segments of normal and balloon-injured rat carotid arteries was studied using a recombinant AAV carrying CMVlacZ as a reporter gene. Approximately 10(6) and 10(7) infectious units (IU) of AAV were infused into 1 cm isolated segments of the carotid artery of 14 animals with the aid of a Silastic catheter and allowed to remain for 20 min. Animals were killed at different time-points after infection and arteries stained for beta-gal activity. Microscopic examination demonstrated comparable gene transfer into medial and adventitial cells, with significantly higher efficiency of transduction in injured as compared with normal vessels. High levels of in vivo beta-gal expression persisted for at least 30 days after gene transfer. Thus, AAV is capable of transducing media and adventitia of rat carotid arteries, suggesting that it may constitute a useful vector for arterial gene transfer and gene therapy protocols.