RESUMO
Recently, several groups have reported that Ras association domain family 1 (RASSF1A) interacts with Ras and mediates Ras-dependent apoptosis. However, the mechanism by which RASSF1A plays a role as a tumor suppressor in human cancer is unclear. In this study, we investigated the relationship between the RASSF1A methylation and K-ras mutation and their effects on patient's survival in 242 primary non-small cell lung cancers (NSCLCs) to understand the role of RASSF1A in Ras-mediated oncogenic transformation. RASSF1A methylation was not found to be associated with the K-ras mutation in NSCLCs (P = 0.37). For patients with stage I adenocarcinoma, those with RASSF1A methylation and K-ras mutation had a poorer prognosis than those with either RASSF1A methylation or K-ras mutation (P = 0.001). In stage II-III adenocarcinoma patients, the median survival of those with RASSF1A methylation and K-ras mutation was 9 months, and this was poorer than that of those with either RASSF1A methylation or K-ras mutation (P = 0.001). The hazard of failure for those with RASSF1A methylation and K-ras mutation was approximately 2.94 times higher compared with that of those with neither K-ras mutation nor RASSF1A methylation (95% confidence interval = 1.67-9.42; P = 0.01). Our results suggest that RASSF1A methylation and K-ras mutation are not mutually exclusive in NSCLC. In addition, RASSF1A methylation, in combination with K-ras mutation, may have an adverse synergistic effect on patient's survival in NSCLCs.
Assuntos
Carcinoma Pulmonar de Células não Pequenas/genética , Metilação de DNA , Genes ras/genética , Neoplasias Pulmonares/genética , Mutação , Proteínas de Neoplasias/genética , Proteínas Supressoras de Tumor , Idoso , Carcinoma Pulmonar de Células não Pequenas/patologia , Códon , Feminino , Genes Supressores de Tumor , Humanos , Neoplasias Pulmonares/patologia , Masculino , Regiões Promotoras Genéticas , Modelos de Riscos Proporcionais , Taxa de SobrevidaRESUMO
Apoptosis-resistant dihydrofolate reductase-deficient CHO cell line (dhfr(-) CHO-bcl2) was developed by introduction of the bcl-2 gene into the dhfr(-) CHO cell line (DUKX-B11, ATCC CRL-9096) and subsequent selection of clones stably overexpressing Bcl-2 in the absence of selection pressure. When the dhfr(-) CHO-bcl2 cell line was used as a host cell line for development of a recombinant CHO (rCHO) cell line expressing a humanized antibody, it displayed stable expression of the bcl-2 gene during rCHO cell line development and no detrimental effect of Bcl-2 overexpression on specific antibody productivity. Taken together, the results obtained demonstrate that the use of an apoptosis-resistant dhfr(-) CHO cell line as the host cell line saves the effort of establishing an apoptosis-resistant rCHO cell line and expedites the development process of apoptosis-resistant rCHO cells producing therapeutic proteins.
