RESUMO
To explore the basis of metastasis, we compared the human breast cancer lines MCF-7 and MDA-MB453, which have low invasive ability, with their sublines MCF7-I4 and MDA-MB453-I4 with high invasive ability for gene expression and signaling pathways. We previously showed that the I4 lines had dramatically elevated levels of Twist compared with their parental lines. In this study, we observed significantly increased STAT3 Tyr(705) phosphorylation, but not the STAT3 protein levels, in the I4 lines. Activation of STAT3 by interleukin-6 or expression of activated Src induced Twist expression at protein and mRNA levels. Inhibiting STAT3 by a small molecule inhibitor, JSI-124, STAT3 small hairpin RNAs, or dominant negative STAT3 resulted in significant reduction of Twist protein and mRNA expression. STAT3 directly bound to the second proximal STAT3-binding site on the human Twist promoter and activated its transcriptional activity. Inhibition of STAT3 reduced migration, invasion, and colony formation of the I4 cells. Ectopic expression of Twist significantly rescued those phenotypes. Ten normal and 46 tumor specimens of breast tissues were examined for activation of STAT3 and expression of Twist. There was a strong correlation between Tyr(705) p-STAT3 and Twist level in the late stage tumor tissues. Our results indicate that activated STAT3 transcriptionally induces Twist, which plays an important role in promoting migration, invasion, and anchorage-independent growth. Together with our previous observation that Twist transcriptionally induces AKT2 to mediate Twist-promoted oncogenic functions, we conclude that STAT3, Twist, and AKT2 form a functional signaling axis to regulate pivotal oncogenic properties of cancer cells.
Assuntos
Proteínas Oncogênicas/metabolismo , Fator de Transcrição STAT3/metabolismo , Transcrição Gênica/genética , Proteína 1 Relacionada a Twist/metabolismo , Neoplasias da Mama/genética , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Movimento Celular , Regulação da Expressão Gênica , Humanos , Dados de Sequência Molecular , Regiões Promotoras Genéticas/genética , Ligação Proteica , RNA Mensageiro/genética , Fator de Transcrição STAT3/genética , Proteína 1 Relacionada a Twist/genéticaRESUMO
An alkaliphilic and slightly halophilic Gram-positive rod, designated strain F10, was isolated from Haoji soda lake in Inner Mongolia Autonomous Region, China. Strain F10 grew optimally in the presence of 3% (W/V) NaCl, pH 9.5 and 37 degrees C. It was facultatively anaerobic, motile with peritrichous flagella, sporulating, catalase- negative. The (G + C) content of the DNA was 40 mol%. The cell wall contained meso-DAP. Phylogenetic analyses based on 16S rDNA sequences comparisons indicate that strain F10 was a member of the genus Amphibacillus. DNA-DNA similarity of less than 30% with the described species of Amphibacillus supported the view that this organism represented a new species of the genus Amphibacillus. The name Amphibacillus haojiensis sp. nov. is proposed.
