Proteomic analysis reveals overexpression of moesin and cytokeratin 17 proteins in colorectal carcinoma

The study of tumor biomarkers was gradually facilitated by the adoption of proteomic strategies due to less invasiveness and higher sensitivity. Colorectal cancer is one of the most commonly occurring cancers worldwide and its incidence has markedly increased in Korea. While the adoption of proteomic strategies facilitated the study of tumor biomarkers, to date, no common agreement has been derived from proteomic investigations regarding tumor markers of colorectal cancer. This study was designed to find molecules differentially expressed in colorectal cancer compared to non-tumor mucosa. Four colorectal adenocarcinoma and corresponding non-tumor tissue samples were analyzed to find previously unknown proteins via two-dimensional electrophoresis and MALDI-TOF/MS spectrometry. Western blot assays and tissue microarray (TMA) immunohistochemistry were performed to validate the identified proteins. Among the twelve up-regulated and one down-regulated proteins identified, moesin, cytokeratin (KRT) 17 and carbonic anhydrase I were validated by western blot analysis and/or immunohistochemistry. On immunohistochemistry, both moesin and KRT17 demonstrated a tendency of increased expression as pT stage advanced. Both moesin and KRT17 were not expressed in normal colorectal epithelium. These two proteins may play a role in cancer invasion and/or metastasis in colorectal carcinoma, and could be candidate biomarkers for the diagnosis and prognosis of colorectal cancer.