Evaluation of carcinoma‑associated fibroblasts in oral squamous cell carcinoma: a potential role for cathepsin K

Aim The aim of this work was to identify carcinoma‑associated fibroblasts (CAFs) in the stroma of oral squamous cell carcinoma (OSCC), through examining α‑smooth muscle actin (α‑SMA) expression immunohistochemically. Also, to investigate the immunohistochemical expression pattern of cathepsin K (CTSK) in CAFs as well as to assess the expression level of CTSK mRNA in CAFs, by real‑time reverse transcription PCR (RT‑PCR) technique. Furthermore, to correlate CTSK expression in different histopathological grades of OSCC, in order to identify its potential role in tumor progression and aggressiveness. Materials and methods Paraffin‑embedded OSCC specimens were stained immunohistochemically using antibodies against α‑SMA and CTSK. At the same time, level of CTSK mRNA expression was evaluated in fibroblasts indirectly cocultured with OSCC cells by means of real‑time RT‑PCR technique. Results In addition to CTSK coimmunolocalization with α‑SMA in stromal CAFs, its expression by OSCC cells was significantly correlated with increased malignant criteria. Stromal CAFs showed upregulated CTSK expression in poorly differentiated OSCC. Real‑time RT‑PCR results revealed enhanced CTSK mRNA expression by fibroblasts in indirect coculture. Conclusion Collectively, the results propose an evolving role for CTSK in OSCC progression.