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.