S100 Proteins as Diagnostic and Prognostic Markers in Colorectal and Hepatocellular Carcinoma

Context: Clinical and experimental studies have suggested a link between S100 gene expression and neoplastic disorders, however, the molecular mechanisms of this association are not well understood. The aim of this review was to conduct a comprehensive literature search in order to understand the possible underlying molecular mechanisms of this association. We also discuss their application as diagnostic and prognostic markers in colorectal and hepatocellular carcinoma. Evidence Acquisitions: We searched Pubmed (NLM) and Web of Science (ISI Web of Knowledge). Results: S100 genes display a complex expression pattern in colorectal and hepatocellular carcinoma. They are expressed in tumor and/or tumor stroma cells, and they exert both pro- and antitumorigenic actions. In view of this complexity, it becomes clear that S100 proteins might act as both friend and foe. The biological role of the S100 genes is predicted to depend on the relative contributions of the different cell types at specific stages of tumor progression. Conclusions: Further research is required in order to uncover the functional role of S100 genes in tumorigenesis. Answers to this issue are needed before we can more fully understand the clinical relevance of S100 protein expression within epithelial tumors, with regard to their potential applicability as biomarkers for diagnosis and therapy decisions.