PMCC PMCC

Search tips
Search criteria

Advanced
Results 1-3 (3)
 

Clipboard (0)
None
Journals
Authors
more »
Year of Publication
Document Types
1.  Snail1 Protein in the Stroma as a New Putative Prognosis Marker for Colon Tumours 
PLoS ONE  2009;4(5):e5595.
Over-expression of Snail1 gene transcriptional repressor promotes an epithelial-to-mesenchymal transition in epithelial tumour cell lines. Expression of Snail1 RNA has been associated to the pathogenesis of a number of malignancies; however, the lack of good monoclonal antibodies against this protein has precluded a definitive analysis of Snail1 protein. In this study, we aimed to determine the expression of this transcriptional factor in colorectal tumours. Using a Snail1 well-characterized monoclonal antibody developed in our laboratories we have analyzed by immunohistochemistry a cohort of 162 human colorectal tumours. Ninety tumours (56%) showed nuclear expression in the tumoral tissue and the adjacent stroma; in 34 (21%), Snail1 was detected just in the stroma, whereas in only 4 the expression of Snail1 was detected in the tumoral tissue and the stroma was negative. No correlation was found between the presence of Snail1 in the tumour and tumour stage; however, a trend (p = 0.054) was detected when the expression of this factor in the stroma was considered. Snail1 immunoreactivity in this compartment was associated with presence of distant metastasis (p = 0.006). Moreover, expression of Snail1 in the tumor stroma correlated with lower specific survival of cancer patients (p = 0.011). Interestingly, this correlation was also detected in stage I and II tumors. Therefore, our results indicate that the presence of nuclear Snail1 immunoreactive cells in the stroma may be an informative indicator of prognosis of colon tumours especially useful in those corresponding to lower stages and identify a new marker suitable to label activated stroma in colon tumours.
doi:10.1371/journal.pone.0005595
PMCID: PMC2680015  PMID: 19440385
2.  Repression of PTEN Phosphatase by Snail1 Transcriptional Factor during Gamma Radiation-Induced Apoptosis▿  
Molecular and Cellular Biology  2008;28(5):1528-1540.
The product of the Snail1 gene is a transcriptional repressor required for triggering the epithelial-to-mesenchymal transition. Furthermore, ectopic expression of Snail1 in epithelial cells promotes resistance to apoptosis. In this study, we demonstrate that this resistance to γ radiation-induced apoptosis caused by Snail1 is associated with the inhibition of PTEN phosphatase. In MDCK cells, mRNA levels of the p53 target gene PTEN are induced after γ radiation; the transfection of Snail1 prevents this up-regulation. Decreased mRNA levels of PTEN were also detected in RWP-1 cells after the ectopic expression of this transcriptional factor. Snail1 represses and associates to the PTEN promoter as detected both by the electrophoretic mobility shift assay and chromatin immunoprecipitation experiments performed with either endogenous or ectopic Snail1. The binding of Snail1 to the PTEN promoter increases after γ radiation, correlating with the stabilization of Snail1 protein, and prevents the association of p53 to the PTEN promoter. These results stress the critical role of Snail1 in the control of apoptosis and demonstrate the regulation of PTEN phosphatase by this transcriptional repressor.
doi:10.1128/MCB.02061-07
PMCID: PMC2258777  PMID: 18172008
3.  Snail1 transcriptional repressor binds to its own promoter and controls its expression 
Nucleic Acids Research  2006;34(7):2077-2084.
The product of Snail1 gene is a transcriptional repressor of E-cadherin expression and an inductor of the epithelial–mesenchymal transition in several epithelial tumour cell lines. Transcription of Snail1 is induced when epithelial cells are forced to acquire a mesenchymal phenotype. In this work we demonstrate that Snail1 protein limits its own expression: Snail1 binds to an E-box present in its promoter (at −146 with respect to the transcription start) and represses its activity. Therefore, mutation of the E-box increases Snail1 transcription in epithelial and mesenchymal cells. Evidence of binding of ectopic or endogenous Snail1 to its own promoter was obtained by chromatin immunoprecipitation (ChIP) experiments. Studies performed expressing different forms of Snail1 under the control of its own promoter demonstrate that disruption of the regulatory loop increases the cellular levels of Snail protein. These results indicate that expression of Snail1 gene can be regulated by its product and evidence the existence of a fine-tuning feed-back mechanism of regulation of Snail1 transcription.
doi:10.1093/nar/gkl141
PMCID: PMC1440880  PMID: 16617148

Results 1-3 (3)