Epithelial-mesenchymal transition in oral squamous cell carcinoma triggered by transforming growth factor-β1 is Snail family-dependent and correlates with matrix metalloproteinase-2 and -9 expressions

Abstract

Abstract. Snail and Slug play important roles in cancer progression by promoting epithelial-mesenchymal transition (EMT). Although Snail is well studied, its role in oral squamous cell carcinoma (OSCC) and its regulatory relationship with Slug remain unclear. We aimed to determine whether Snail and Slug interplay occurs in transforming growth factor-ß1 (TGF-ß1)-initiated EMT of OSCC cells, and to assess the expression of matrix metalloproteinases (MMPs) in this process. Three OSCC cell lines, SCC9, SCC15 and SCC25 were treated with recombinant TGF-ß1 for 0-6 days. Activities of the EMT regulators, Snail and Slug, and of extracellular hallmarks, MMP2 and 9, were detected using real-time PCR and Western blots. An in vitro wound healing assay then assessed short-term EMT, whilst phenotypic changes associated with the above gene expressions were evaluated by immunocytochemistry. Results showed that Slug and MMP9 were up-regulated at both mRNA and protein levels, while Snail expression rose and fell, in concert with expression of MMP2. In the wound healing assay, Snail was seen alone at the invasive front in SCC9 and SCC15 cultures, while both Snail and Slug appeared at wound margins in SCC25. Both MMP2 and MMP9 were detected at wound edges in all cell lines, with MMP2 localised in cell nuclei, MMP9 was restricted to the cytoplasm. The study suggests that both Snail and Slug act as regulators of TGF-ß1-trigged EMT in OSCC cells. Snail may up-regulate MMP2 or MMP9 initiating EMT, while Slug may share a role with Snail in maintaining longer-term EMT, by stimulating MMP9 expression.

Mechanochemical Signaling of the Extracellular Matrix in Epithelial-Mesenchymal Transition

“…Soluble factors released during tissue remodeling can induce EMT, which in turn stimulates MMP production to sustain remodeling of the ECM for migration (reviewed in Gilles et al, 2013 and Bonnans et al, 2014). Activation of EMT transcription factors corresponds with an increased secretion of gelatinases in human mammary breast cancer epithelium (Octavio et al, 2015) and oral squamous cell carcinoma (Qiao et al, 2010). Specifically, Slug directly enhances MMP1 transcription in breast cancer cells (Shen et al, 2017a) as well as MMP9 in oral squamous cell carcinoma (Joseph et al, 2009), and Snail upregulates MMP9 in MDCKs (Jordà et al, 2005).…”

“…Proteolytically activated growth factors induce these transcription factors, resulting in a positive feedback loop. TGF-β1-dependent EMT triggers gelatinases in oral squamous cell carcinoma by upregulated Snail (Qiao et al, 2010) and MMP10 in keratinocytes (Wilkins-Port and Higgins, 2007). Wnt stimulates MMP production that amplifies tissue remodeling and cell mobility.…”

Histometabolic Tumor Imaging of Hypoxia in Oral Cancer: Clinicopathological Correlation for Prediction of an Aggressive Phenotype

“…This deregulation in cellular energetics is associated with an induction of EMT through downregulation of E-cadherin and upregulation of twist1 and vimentin (6,48). Furthermore, an invasive phenotype is promoted through matrix metalloproteinase upregulation (7). Some data indicate that increased SUV max is associated with increased tissue necrosis assessed by, e.g., cleaved caspase 3 staining (49), further supporting the idea of an association between hypoxia and increased SUV max by FDG-PET.…”

“…Oral squamous cell carcinoma undergoes phenotypic changes to gain migratory and invasive properties through the process of epithelial-mesenchymal transition (EMT) (5,6). Enrichment in EMT sustains transcription of several matrix metalloproteinases, initiating focal matrix degradation and allowing invasion (7). EMT also enhances the glycolytic phenotype of cancer cells that are exposed to hypoxia (6).…”

Neoplastic extracellular matrix environment promotes cancer invasion in vitro

“…Of these growth factors, TGF-β1 and HGF are of special interest, since TGF-β1 induced myofibroblasts are shown to secrete HGF that increases invasion of OSCC cells in vitro [6,18]. Additionally, TGF-β1 induces an epithelial-mesenchymal transition (EMT) in OSCC cells, a process in which cells of epithelial origin gain properties of mesenchymal cells, including loss of adhesion and increased migratory capabilities [25]. Some of the changes between invasion in native and rinsed myomas detected previously [31] could be attributed to these migration and invasion increasing growth factors in myoma rinsing media.…”