The analysis of S100A9 and S100A8 expression in matched sets of macroscopically normal colon mucosa and colorectal carcinoma: The S100A9 and S100A8 positive cells underlie and invade tumor mass

The expression of calcium-binding protein S100A9 was investigated in 23 mat ched sets of colorectal carcinoma and normal colon mucosa using two-dimensi onal gel electrophoresis. We found that, from a group of 23 patients, the l evel of S100A9 protein, in comparison with matched normal colon mucosa, was significantly increased in malignant tissues of 16 patients (70%). Further more, an additional protein, identified by matrix-assisted laser desorption /ionization - mass spectrometry (MALDI-MS) as S100A8, exhibited an increase d expression in the same specimens of malignant tissues as the S100A9 prote in. The immunohistological analysis revealed the accumulation of S100A9 pos itive cells, macrophages and polymorphonuclear leukocytes along the invasiv e margin of colorectal carcinoma. The S100A8 protein was found to be produc ed in the same location. The possible participation of both proteins and, e specially, its heterodimeric complex calprotectin in colorectal carcinoma r egression could be taken into account.