Background: Cutaneous squamous cell carcinoma (cSCC) is a common skin cancer. Most patients who develop metastases (2-5%) present with advanced disease that requires a combination of radical surgery and adjuvant radiation therapy. Consequently, predicting metastasis and targeting underlying processes remains a major challenge in managing cSCC. Epithelial-mesenchymal transition (EMT) is a driving process implicated in metastasis in many cancers. Several reports also suggest the drug induced reversibility of EMT‑phenotypes and the value of these drugs as adjuvant therapies. From the literature and our own targeted gene expression analysis we have identified potential EMT markers particularly relevant to cSCC progression. However, drug induced reversal or targeting of EMT biomarkers in cSCC has not been explored beyond a few select targets like COX2 and EphB2.
Aim: To characterize EMT in our patient-derived metastatic cSCC cell lines, UW‑CSCC1 and UW‑CSCC2, and identify drug targets modulating EMT-parameters.
Methods: The cell lines were cultured with growth factors and drugs with known roles in modulating EMT. The EMT-phenotype of these cultures was determined through western blot and immunocytochemical analysis of key marker protein expression. Changes in migratory properties were assessed using a scratch wound assay.
Results: Our cell lines, UW-CSCC1 and UW-CSCC2, take respectively a more mesenchymal and epithelial positon along the epithelial-mesenchymal spectrum. UW-CSCC2 displays a distinct cobblestone growth pattern paired with E-cadherin whereas UW-CSCC1 lacks both of those features. Growth factors induce changes consistent with a progression towards a more motile mesenchymal phenotype such as increases in motility and shifts in cytokeratin expression towards lower molecular weight cytokeratins. An inhibitor of focal adhesion kinase could modulate invasive properties by reducing activity of the urokinase plasminogen activator system, an emerging EMT biomarker.
Conclusion: EMT is a driving process cSCC metastasis and the patient-derived cell lines 3-dimensional in vitro models of UW‑CSCC1 and UW‑CSCC2 are being developed for validation of these EMT studies.