RESUMO
Gene amplification is a major genetic alteration in human cancers. Amplicons, amplified genomic regions, are believed to contain "driver" genes responsible for tumorigenesis. However, the significance of co-amplified genes has not been extensively studied. We have established an integrated analysis system of amplicons using retrovirus-mediated gene transfer coupled with a human full-length cDNA set. Applying this system to 17q12-21 amplicon observed in breast cancer, we identified GRB7 as a context-dependent oncogene, which modulates the ERBB2 signaling pathway through enhanced phosphorylation of ERBB2 and Akt. Our work provides an insight into the biological significance of gene amplification in human cancers.
Assuntos
Transformação Celular Neoplásica/genética , Cromossomos Humanos Par 17/genética , Proteína Adaptadora GRB7/genética , Proto-Oncogenes , Receptor ErbB-2/genética , Animais , Regulação para Baixo , Proteína Adaptadora GRB7/metabolismo , Amplificação de Genes , Humanos , Camundongos , Mutagênese , Células NIH 3T3 , Fosforilação , Mutação Puntual , Processamento de Proteína Pós-Traducional , Estrutura Terciária de Proteína/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo , Receptor ErbB-2/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Deleção de Sequência , Transdução de SinaisRESUMO
Overexpression of ErbB2 in breast cancer is associated with increased recurrence and worse prognosis. Accumulating evidences suggest that molecular targeted therapy is a promising anticancer strategy. In this study, we produced a novel anti-ErbB2 monoclonal antibody, 6G10, that recognized an epitope distinct from the trastuzumab binding site. 6G10 induced aggregation of BT474 breast cancer cells and inhibited proliferation of various breast cancer cell lines including BT474. A growth inhibition assay showed that 6G10 had EC(50) values comparable to trastuzumab, indicating that the drugs have a similar level of potency. Furthermore, intraperitoneal administration of 6G10 completely inhibited the growth of xenografted tumors derived from BT474 and SK-BR-3 cells. These data suggested that 6G10 has great therapeutic potential and could be administered to patients alternatively, or synergistically, with trastuzumab.
Assuntos
Anticorpos Monoclonais/imunologia , Neoplasias da Mama/terapia , Receptor ErbB-2/antagonistas & inibidores , Animais , Anticorpos Monoclonais/uso terapêutico , Linhagem Celular Tumoral , Feminino , Humanos , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos NOD , Receptor ErbB-2/imunologia , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
It is critical to evaluate the overexpression of human epidermal growth factor receptor 2 (HER2) adequately in breast cancer cases. The aim of the present study is to assess the characteristics and usefulness of a novel monoclonal antibody, clone SV2-61gamma. The overexpression of HER2 was studied on paraffin sections of 50 breast cancers using a polyclonal antibody assay (HercepTest) and monoclonal antibodies (clones SV2-61gamma and CB11). Gene amplification of HER2 was determined by fluorescent in situ hybridization (FISH) using a HER2/CEP17DNA probe kit. Fifty tumors were scored as 0 (50.0%), 1+ (26.0%), 2+ (4.0%), or 3+ (20.0%) by immunohistochemistry using a monoclonal antibody, clone SV2-61gamma. The specificities of immunohistochemistry were 72.0% for the polyclonal antibody, 97.0% for SV2-61gamma, and 92.0% for CB11. The concordances with FISH were 78.0% for the polyclonal antibody, 98.0% for SV2-61gamma, and 94.0% for CB11. The positive predictive value of SV2-61gamma (92.0%) was higher than those of the polyclonal antibody (50.0%) and CB11 (79.0%). A monoclonal antibody clone SV2-61gamma showed very specific staining, with the best concordance with FISH, and it is useful for the evaluation of HER2 overexpression.