RESUMO
Overexpression of RhoA or RhoC in breast cancer indicates a poor prognosis, due to increased tumor cell proliferation and invasion and tumor-dependent angiogenesis. Until now, the strategy of blockage of the Rho-signaling pathway has used either GGTI or HMG-CoA reductase inhibitors, but they are not specific to RhoA or RhoC inhibition. In this study, a new approach with anti-RhoA and anti-RhoC siRNAs was used to inhibit specifically RhoA or RhoC synthesis. Two transfections of either RhoA or RhoC siRNA (8.5 nM) into MDA-MB-231 human breast cancer cells or HMEC-1 endothelial cells induced extensive degradation of the target mRNA and led to a dramatic decrease in synthesis of the corresponding protein. In vitro, these siRNAs inhibited cell proliferation and invasion more effectively than conventional blockers of Rho cell signaling. Finally, in a nude mouse model, intratumoral injections of anti-RhoA siRNA (100 microl at 85 nM) every 3 days for 20 days almost totally inhibited the growth and angiogenesis of xenografted MDA-MB-231 tumors. One may infer from these observations that specific inhibition of the Rho-signaling pathway with siRNAs represents a promising approach for the treatment of aggressive breast cancers.
Assuntos
Neoplasias da Mama/genética , Neoplasias da Mama/patologia , RNA Interferente Pequeno/metabolismo , Proteínas rho de Ligação ao GTP/deficiência , Proteínas rho de Ligação ao GTP/genética , Proteína rhoA de Ligação ao GTP/deficiência , Proteína rhoA de Ligação ao GTP/genética , Transporte Ativo do Núcleo Celular , Animais , Neoplasias da Mama/irrigação sanguínea , Neoplasias da Mama/metabolismo , Linhagem Celular Tumoral , Núcleo Celular/metabolismo , Proliferação de Células , Colágeno , Proteínas do Citoesqueleto/metabolismo , Regulação para Baixo/genética , Combinação de Medicamentos , Inibidores Enzimáticos/farmacologia , Regulação Neoplásica da Expressão Gênica , Humanos , Laminina , Camundongos , Invasividade Neoplásica/genética , Invasividade Neoplásica/prevenção & controle , Neovascularização Patológica , Proteoglicanas , Piridinas/farmacologia , Interferência de RNA , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RNA Interferente Pequeno/genética , Transativadores/metabolismo , Transfecção , beta Catenina , Proteínas ras , Proteínas rho de Ligação ao GTP/metabolismo , Proteína rhoA de Ligação ao GTP/metabolismo , Proteína de Ligação a GTP rhoCRESUMO
Fenofibrate, a peroxisome proliferator-activated receptor (PPAR)-alpha activator, used as a normolipidemic agent, is thought to offer additional beneficial effects in atherosclerosis. Since angiogenesis is involved in plaque progression, hemorrhage, and instability, the main causes of ischemic events, this study was designed to evaluate the action of fenofibrate on angiogenesis. Our results show that fenofibrate (i) inhibits endothelial cell proliferation induced by angiogenic factors, followed at high concentrations by an increase in apoptosis, (ii) inhibits endothelial cell migration in a healing wound model, (iii) inhibits capillary tube formation in vitro, and (iv) inhibits angiogenesis in vivo. Concerning the mechanism of action, the inhibition of endothelial cell migration by fenofibrate can be explained by a disorganization of the actin cytoskeleton. At the molecular level, fenofibrate markedly decreased basic fibroblast growth factor-induced Akt activation and cyclooxygenase 2 gene expression. This inhibition of angiogenesis could participate in the beneficial effect of fenofibrate in atherosclerosis.
