RESUMO
Snail, a zinc-finger transcriptional repressor of E-cadherin expression, is one of the key inducers of epithelial-mesenchymal transition (EMT) in epithelial cancer. In breast cancer, EMT has been associated with malignancies, including metastasis, cancer stem-like properties, and resistance to chemotherapy and radiotherapy. In this study, we analysed the role of Snail in the highly metastatic mesenchymal TUBOP2J mouse breast cancer cells, by loss of function using short hairpin RNA. Though silencing Snail did not restore the E-cadherin expression or induce morphological changes, Snail silencing significantly ablated in vitro and in vivo metastatic potentials. In addition, Snail silencing also reduced resistance to chemotherapy drugs and cancer stem-like properties, such as CD44 expression, aldehyde dehydrogenase (ALDH) activity, colony formation, and in vivo tumour formation and growth. However, radioresistance was not decreased by silencing Snail. Collectively, this study suggested that Snail is a main regulator of the maintenance of malignancy potentials and is a good target to prevent cancer metastasis and to increase chemotherapy susceptibility.
Assuntos
Neoplasias da Mama/genética , Resistencia a Medicamentos Antineoplásicos/genética , Transição Epitelial-Mesenquimal/genética , Receptores de Hialuronatos/genética , Células-Tronco Neoplásicas/fisiologia , Fatores de Transcrição da Família Snail/genética , Animais , Neoplasias da Mama/patologia , Caderinas/genética , Linhagem Celular Tumoral , Movimento Celular/genética , Feminino , Regulação Neoplásica da Expressão Gênica/genética , Humanos , Camundongos , Camundongos Endogâmicos BALB C , RNA Mensageiro/genética , RNA Interferente Pequeno/genética , Fatores de Transcrição/genéticaRESUMO
This study investigated the therapeutic effects of combined local irradiation and anti-HER2/neu antibody in a mixed tumor mouse model comprised of a nonmetastatic neu-positive tumor and a metastatic neu-negative tumor. While local irradiation alone could control the primary tumor in a dose-dependent manner, it did not improve mouse survival. Combined treatment comprised of local irradiation and anti-neu antibody of tumor-bearing BALB/c mice significantly improved mouse survival (P < 0.5), even though the tumor growth was similar to that of the irradiated-alone group. The combined treatment significantly reduced metastatic tumor masses in the lung and increased immune cell infiltration in primary tumor tissues. However, immune deficient nude mice with tumors did not exhibit prolonged survival in response to the combined treatment. Collectively, these results show that combined local irradiation and anti-neu antibody can elicit an immune-mediated abscopal effect to extend survival. Although the mechanism for abscopal effects induced by the combined treatment of radiation and anti-HER2/neu antibody was not elucidated, to our knowledge this is the first published study to describe the abscopal effect induced by the combination of local irradiation and the anti-HER2/neu antibody.