Analysis of citrullination of extracellular matrix proteins in spheroid cultures of fibroblasts and cancer cells

Eight different human cancer cell lines were cocultured with human cancer associated fibroblasts (CAF) as spheroid cultures. In another setup UT-SCC-7 cutaneous squamous cell carcinoma cells, together with human skin fibroblasts (SFB) and UT-SCC-2 cells together with gingival fibroblasts (GFB) were cultured as spheroid cocultures. These spheroids were treated with PAD4 or with citrullination buffer only. All spheroids were hypotonically lysed, and the remaining insoluble material was digested to peptides and analysed by LC-MS/MS.