Recent advances in the study of phenomena leading to cancer show that each tumor has their own pathophysiological characteristics. The contribution of biomarkers to achieve specific molecular diagnostics is a key issue. A comprehensive quantitative proteomic analysis based on the use of iTRAQ labeling was performed on frozen colorectal tumors. These tumors were analyzed according to their TNM stage on one hand, and their status of the KRAS oncogene in another hand. To complete our analysis we also analyzed the proteome of colorectal cell lines. We also examined the stroma of these tumor, and we have developed a technique for analyzing a subproteome : the glycoproteome. All these results led us to propose a database of proteins identified in this model with 3168 proteins. 513 proteins we identified are likely to be secreted by tumors and constitute a database of candidate biomarkers for colorectal cancer. We also validated one of them : OLFM4. This is a potential candidate biomarker for the early detection of colorectal cancer, and we also demonstrated that the expression level was changed when the tumor has expressed KRAS oncogene. We are also interested in its cellular functions, and we showed that it was involved in tumor resistance to treatment, and it is likely to play a role in tumor dissemination.
