RESUMO
The regulators of a key metastasis gene PRL-3 in colorectal cancer (CRC) are still largely unknown. We found three potential binding sites of Snail, a key transcriptional factor involved in the epithelial-mesenchymal transition (EMT), in the region of PRL-3 promoter (located at -642 to -383). Moreover, our results showed that one of the Snail binding sites (located at -624 to -619) was the key element to maintain promoter activity of human PRL-3 gene. The transcriptional activity of PRL-3 promoter was abolished after the Snail binding site (located at -624 to -619) was mutated. Both promoter activity and protein expression of PRL-3 in CRC cell lines could be regulated by Snail. In clinical samples of CRC and metastatic lymph node of CRC, expression of PRL-3 protein was correlated with expression of Snail protein. Functional studies using gene over-expression and knockdown methods indicated that Snail promoted proliferation, cell adhesion and migration of human CRC cells. In SW480 cells with PRL-3 stable knockdown, cell proliferation increased after Snail was up-regulated. Our data first reveal transcriptional factor Snail as a key regulator of PRL-3 in CRC. The link between Snail and PRL-3 suggests a new potential mechanism of Snail contributing to progression and metastasis of CRC.
Assuntos
Neoplasias Colorretais/genética , Regulação Neoplásica da Expressão Gênica , Proteínas de Neoplasias/genética , Proteínas Tirosina Fosfatases/genética , Fatores de Transcrição/metabolismo , Sítios de Ligação , Adesão Celular/genética , Processos de Crescimento Celular/genética , Linhagem Celular Tumoral , Movimento Celular/genética , Neoplasias Colorretais/metabolismo , Neoplasias Colorretais/patologia , Feminino , Técnicas de Silenciamento de Genes , Humanos , Masculino , Proteínas de Neoplasias/metabolismo , Regiões Promotoras Genéticas , Proteínas Tirosina Fosfatases/metabolismo , Elementos Reguladores de Transcrição , Fatores de Transcrição da Família Snail , Transcrição Gênica , Dedos de ZincoRESUMO
OBJECTIVE: To study expression of the zinc finger transcriptional factor Snail in colorectal carcinoma and its significance. METHODS: Expressions of Snail in colorectal carcinoma SW480 and SW620 cells were assayed by immunocytochemistry and immunofluorescent cytochemistry. The paraffin-embedded specimens from 68 cases of colorectal carcinoma and its corresponding adjacent tissues, 33 cases of adenoma and 35 cases of metastatic lymph nodes were also examined for Snail expressions using immunohistochemistry. RESULTS: Snail protein was located mainly in the cell nucleus of SW480 and SW620 cells. The expressions of PRL-3 protein in the specimens of colorectal carcinoma, normal mucosa, adenoma and metastatic lymph nodes were significantly different (Chi(2)=92.852, P=0.000). In the adenoma tissues, the expression was significantly higher than that in normal mucosa (Z=-2.902, P=0.004), the metastatic lymphnodes had significantly higher expressions than the primary colorectal carcinomas (Z=-4.951, P=0.000), which, in turn, showed significantly higher expression than the adenoma tissues (Z=-3.572, P=0.000). Significant correlation of Snail expression was found to the progression and metastasis of colorectal carcinoma (Z=-2.043, P=0.041). CONCLUSION: The expression of Snail is significantly correlated to genesis, progression and metastasis of colorectal carcinoma.