Abstract
The Snail transcription factor plays as a master regulator of epithelial mesenchymal transition (EMT), one of the steps of tumor metastasis. Snail enhances expressions of a lot of mesenchymal genes including the matrix degradation enzyme matrix metalloproteinases 9 (MMP9) and the EMT transcription factor zinc finger E-box binding homeobox 1 (ZEB1), however, the underlying mechanisms are not clarified. Herein, we investigated how Snail upregulated transcription of ZEB1 and MMP9 induced by the tumor promoter 12-O-tetradecanoyl-phorbol 13-acetate (TPA) in hepatoma cell HepG2. According to deletion mapping and site directed mutagenesis analysis, the TPA-responsive elements on both MMP9 and ZEB1 promoters locate on a putative EGR1 and SP1 overlapping region coupled with an upstream proposed Snail binding motif TCACA. Consistently, chromatin immunoprecipitation (ChIP) assay showed TPA triggered binding of Snail, EGR1 and SP1 on MMP9 and ZEB1 promoters. Double ChIP further indicated TPA induced association of Snail with EGR1 and SP1 on both promoters. Also, electrophoresis mobility shift assay revealed TPA enhanced binding of Snail with a MMP9 promoter fragment. According to shRNA techniques, Snail was essential for gene expression of both ZEB1 and MMP9. In conclusion, Snail transactivates genes involved in tumor progression via direct binding to a specific promoter region.
Highlights
The Snail transcription factor plays as a master regulator of epithelial mesenchymal transition (EMT), one of the steps of tumor metastasis
Our recent study indicated that Snail, in collaboration with EGR1 and SP1, may directly activate transcription of the inhibitor of cyclin-dependent kinase 4/6 (CDK4/6), p15INK4b, in HepG2 cell stimulated by the phorbol ester tumor promoter 12-O-tetradecanoyl-phorbol 13-acetate (TPA)[23]
RT-PCR showed slight induction of matrix metalloproteinases 9 (MMP9) mRNA induced by TPA at at 3 and 6 h, which further increased by 4.1-fold at 9 h and declined to basal level until 24 h (Fig. 1B, upper panel)
Summary
The Snail transcription factor plays as a master regulator of epithelial mesenchymal transition (EMT), one of the steps of tumor metastasis. Snail enhances expressions of a lot of mesenchymal genes including the matrix degradation enzyme matrix metalloproteinases 9 (MMP9) and the EMT transcription factor zinc finger E-box binding homeobox 1 (ZEB1), the underlying mechanisms are not clarified. Snail may enhance mesenchymal markers including fibronectin, collagens, the matrix degradation enzyme matrix metalloproteinases 2 and 9 (MMP2 and MMP9) and other EMT transcription factors such as Twist and zinc finger E-box binding homeobox 1 (ZEB1)[8,12]. Our recent study indicated that Snail, in collaboration with EGR1 and SP1, may directly activate transcription of the inhibitor of cyclin-dependent kinase 4/6 (CDK4/6), p15INK4b, in HepG2 cell stimulated by the phorbol ester tumor promoter 12-O-tetradecanoyl-phorbol 13-acetate (TPA)[23]. It is tempting to investigate whether there is consensus mechanism for Snail to upregulate gene expression via direct binding to specific promoter region
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
