IL-1α induces cathepsin K in oral cancer cells – the invasion is unaffected

Background: To study cathepsin K location in oral tongue squamous cell carcinoma (OTSCC), its traffic and expression levels in cultured oral cell lines; and to analyze the effect of interleukin (IL)-1α on OTSCC invasion. Methods: Cathepsin K expression in OTSCC tissue samples was analyzed with immunostaining; its intracellular traffic was followed in HSC-3 cells after PMA treatment. HSC-3 and two oral keratinocyte cell lines, oral carcinoma associated fibroblasts (CAFs) and primary gingival fibroblasts (GF) were treated with IL-1α. Cathepsin K expression was measured using PCR and ELISA. Lastly, the effects of IL-1α on HSC-3 invasiveness, alone and in co-cultures with fibroblasts in the 3D myoma invasion model, were determined. Results: Cathepsin K in OTSCC cells was found in vesicles close to cell membrane and within exosomes. While cathepsin K was expressed at the basal level in both epithelial cells and fibroblasts, basal IL-1α levels were higher in epithelial cells compared with GFs and CAFs. Cathepsin K expression was slightly induced by IL-1α in all cell lines, but it did not affect HSC-3 invasiveness. Conclusion: In OTSCC, cathepsin K remains mostly intracellular and it is slightly secreted within exosomes. IL-1α treatment has no effect on HSC-3 invasiveness in 3D myoma model.