Abstract
Epithelial-mesenchymal transition (EMT) is a biological process by which epithelial cells acquire mesenchymal characteristics. In malignant tumors, EMT is crucial for acquisition of a mesenchymal phenotype with invasive and metastatic properties, leading to tumor progression. An inflammatory microenvironment is thought to be responsible for the development and progression of colorectal cancer (CRC); however, the precise role of inflammatory microenvironments in EMT-related CRC progression remains unclear. Here, we show the spatiotemporal visualization of CRC cells undergoing EMT using a fluorescence-guided EMT imaging system in which the mesenchymal vimentin promoter drives red fluorescent protein (RFP) expression. An inflammatory microenvironment including TNF-α, IL-1β, and cytokine-secreting inflammatory macrophages induced RFP expression in association with the EMT phenotype in CRC cells. In vivo experiments further demonstrated the distribution of RFP-positive CRC cells in rectal and metastatic tumors. Our data suggest that the EMT imaging system described here is a powerful tool for monitoring EMT in inflammatory microenvironment–CRC networks.
Highlights
Epithelial-mesenchymal transition (EMT) is a biological process by which epithelial cells acquire mesenchymal characteristics
As EMT is positively regulated by EMT-related transcription factors (EMT-TFs) that bind to the promoter region of the target gene and negatively regulated by EMT-miRNAs that bind to the 3′-untranslated region (3′-UTR) of the target gene, the promoter region and 3′-UTR of the gene encoding the mesenchymal marker VIM were cloned from human normal fibroblast WI-38 cells
Previous reports have shown that HCT116 human colorectal cancer (CRC) cells exhibit an epithelial phenotype and that EMT is induced in these cells by treatment with inflammatory cytokines such as TNF-α29 or IL-1β30
Summary
Epithelial-mesenchymal transition (EMT) is a biological process by which epithelial cells acquire mesenchymal characteristics. An inflammatory microenvironment including TNF-α, IL-1β, and cytokine-secreting inflammatory macrophages induced RFP expression in association with the EMT phenotype in CRC cells. In the chronic inflammatory phase[16,17,18,19], several growth factors, including epidermal growth factor (EGF), basic fibroblast growth factor (bFGF), and hepatocyte growth factor (HGF), accumulate with proliferation of stromal fibroblasts in the ECM It remains unclear how an inflammatory microenvironment induces EMT during CRC progression. Fischer et al developed a mesenchymal marker–specific Cre-mediated fluorescent switching system[12,22] in which the fibroblast-specific protein 1 promoter drives the Cre-lox recombination system to induce expression of green fluorescent protein (GFP) in cells undergoing EMT This switching is not reversible, and GFP-positive tumor cells can include epithelial-type cells that undergo EMT. EMT involves a complex regulatory network consisting of EMT-TFs, EMT-miRNAs, and epithelial and mesenchymal marker genes
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.
