RESUMO
The Rho proteins are Ras-related guanosine triphosphatases (GTPases) that function in cytoskeletal reorganization, cell migration, and stress fiber and focal adhesion formation. Overexpression of RhoC enhances the ability of melanoma cells to exit the blood and colonize the lungs. However, in vivo confirmation of RhoC's role in metastasis has awaited a RhoC-deficient mouse model. Here we report the generation of RhoC-deficient mice and show that RhoC is dispensable for embryonic and post-natal development. We demonstrate that loss of RhoC does not affect tumor development but decreases tumor cell motility and metastatic cell survival leading to a drastic inhibition of metastasis.
Assuntos
Desenvolvimento Embrionário/fisiologia , Metástase Neoplásica/fisiopatologia , Neoplasias Experimentais/etiologia , Proteínas rho de Ligação ao GTP/fisiologia , Animais , Linfócitos B/imunologia , Movimento Celular , Sobrevivência Celular , Transformação Celular Neoplásica , Feminino , Ativação Linfocitária , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Metástase Neoplásica/patologia , Neoplasias Experimentais/patologia , Gravidez , Linfócitos T/imunologia , Proteínas ras , Proteínas rho de Ligação ao GTP/deficiência , Proteínas rho de Ligação ao GTP/genética , Proteínas rho de Ligação ao GTP/imunologia , Proteína de Ligação a GTP rhoCRESUMO
Mus81-Eme1 endonuclease has been implicated in the rescue of stalled replication forks and the resolution of meiotic recombination intermediates in yeast. We used gene targeting to study the physiological requirements of Mus81 in mammals. Mus81-/- mice are viable and fertile, which indicates that mammalian Mus81 is not essential for recombination processes associated with meiosis. Mus81-deficient mice and cells were hypersensitive to the DNA cross-linking agent mitomycin C but not to gamma-irradiation. Remarkably, both homozygous Mus81-/- and heterozygous Mus81+/- mice exhibited a similar susceptibility to spontaneous chromosomal damage and a profound and equivalent predisposition to lymphomas and other cancers. These studies demonstrate a critical role for the proper biallelic expression of the mammalian Mus81 in the maintenance of genomic integrity and tumor suppression.
Assuntos
Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/fisiologia , Endonucleases , Genoma , Instabilidade Genômica , Neoplasias/genética , Alelos , Animais , Aberrações Cromossômicas , Dano ao DNA , Embrião de Mamíferos/citologia , Desenvolvimento Embrionário e Fetal , Raios gama , Marcação de Genes , Predisposição Genética para Doença , Heterozigoto , Linfoma/etiologia , Linfoma/genética , Linfoma/patologia , Meiose , Camundongos , Mitomicina/farmacologia , Neoplasias/etiologia , Recombinação Genética , Proteínas de Saccharomyces cerevisiae , Troca de Cromátide Irmã , Células-Tronco , Linfócitos T/fisiologiaRESUMO
Disruption of Brca1 results in cellular demise or tumorigenesis depending on cellular context. Inactivation of p53 contributes to Brca1-associated tumor susceptibility. However the activation of p53-dependent checkpoint/apoptotic signaling in the absence of Brca1 is poorly understood. Here, we show that Chk2 inactivation is partially equivalent to p53 inactivation, in that Chk2 deficiency facilitates the development, survival, and proliferation of Brca1-deficient T cells at the expense of genomic integrity. Brca1 deficiency was found to result in Chk2 phosphorylation and the Chk2-dependent accumulation and activation of p53. Furthermore, inactivation of Chk2 and Brca1 was cooperative in breast cancer. Our findings identify a critical role for Chk2 as a component of the DNA damage-signaling pathway activated in response to Brca1 deficiency.
Assuntos
Genes BRCA1 , Neoplasias Experimentais/genética , Proteínas Serina-Treonina Quinases/genética , Animais , Quinase do Ponto de Checagem 2 , Aberrações Cromossômicas , Cocarcinogênese , Feminino , Genes p53 , Humanos , Linfoma de Células T/genética , Linfoma de Células T/patologia , Neoplasias Mamárias Experimentais/genética , Neoplasias Mamárias Experimentais/patologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Neoplasias Experimentais/patologia , Proteínas Serina-Treonina Quinases/deficiência , Tolerância a Radiação/genética , Linfócitos T/metabolismo , Linfócitos T/efeitos da radiaçãoRESUMO
We have successfully achieved selective gene expression in human nasopharyngeal carcinoma (NPC) by exploiting the presence of the Epstein-Barr virus (EBV), utilizing a transcriptional targeting strategy (J. H. Li et al., 2002, Cancer Res. 62: 171). Building on this platform, we have generated a novel DeltaE1 adenoviral vector mediating the expression of a mutant noncleavable form of the FasL gene (HUGO-approved symbol TNFSF6) (ad5oriP.ncFasL). We observe that this therapy induces significant cytotoxicity in the EBV-positive NPC cell line C666-1, mediated by the induction of caspase-dependent apoptosis. The addition of ionizing radiation therapy (RT) causes additional cytotoxicity. Ex vivo infection of C666-1 cells with adv.oriP.ncFasL completely prevents tumor formation in SCID mice followed for up to 100 days. The combination of intratumoral adv.oriP.ncFasL with RT causes regression of established nasopharyngeal xenograft tumors for 2 weeks' duration. Systemic delivery of this targeted strategy achieves 50-fold higher gene expression in nasopharyngeal tumors than in normal organs. Intravenously injected adv.oriP.ncFasL results in mild perturbation of liver function that returns to normal 2 weeks after initial therapy. These results demonstrate the efficacy of our EBV-specific targeting strategy, which allows the potentially safe and effective utilization of a highly potent membrane-based apoptotic gene.