The definition of the secretome signature of a cancer cell line can be considered a potential tool to investigate tumor aggressiveness and a preclinical exploratory study required to optimize the search of cancer biomarkers. Dealing with a cell-specific secretome limits the contamination by the major components of the human serum and reduces the range of dynamic concentrations among the secreted proteins, thus favouring under-represented tissue-specific species. The aim of the present study is to characterize the secretome of two human colon carcinoma cell lines, CaCo-2 and HCT-GEO, in order to evaluate differences and similarities of two colorectal cancer model systems. In this study, we identified more than 170 protein species, 64 more expressed in the secretome of CaCo-2 cells and 54 more expressed in the secretome of HCT-GEO cells; 58 proteins were shared by the two systems. Among them, more than 50% were deemed to be secretory according to their Gene Ontology annotation and/or to their SignalP or SecretomeP scores. Such a characterization allowed corroborating the potential of a cell culture-based model in order to describe the cell-specific invasive properties and to provide a list of putative cancer biomarkers. J. Cell. Biochem. 114: 2577–2587, 2013. © 2013 Wiley Periodicals, Inc.