Cathepsin D Expression is Increased by Fibroblasts Stimulation in an Oral Squamous Cell Carcinoma Cell Line

Epithelial mesenchymal interaction(EMI) is well known to be essential in embryonic development, wound healing and carcinogenesis. This study was aimed to design in vitro model for the investigation of protein analysis in epithelial and mesenchymal interaction(EMI). This study used oral squamous cell carcinoma cell line(YD-10B). To investigate the difference of protein expression of cancer cells influenced by variable in vitro conditions, three different models were designed; Collagen gel-based cancer cell culture model devoid of fibroblasts(C), Direct co-culture model(M2) composed of cancer cells beneath collagen gel embedded with Swiss 3T3 fibroblasts, and Indirect co-culture model(M1) with collagen layer between cancer cells and collagen gel with fibroblasts. Two-dimensional electrophoresis was performed to compare the difference of protein expression pattern of cancer cells among three model systems. Protein identification was done by MALDI-TOF. As results, protein expression pattern of cancer cells was quite different between monolayer culture and collagen gel based culture. Additionally, protein expression was different between culture models with fibroblasts and without fibroblasts and between indirect contact and direct contact of two cell types. Among differential protein spots, cathepsin D was identified by MALDI-TOF. Cathepsin D expression was increased from C model to Ml and M2 model by Western blotting, suggesting that cathepsin D expression may be activated by direct and indirect stimulation of stromal fibroblasts. From these results, these models could be appropriate for EMI study and cathepsin D might be induced by fibroblasts stimulation.restrictio