Tenascin C in colorectal cancer stroma is a predictive marker for liver metastasis and is a potent target of miR-198 as identified by microRNA analysis

BACKGROUND: Tumour stroma has important roles in the development of colorectal cancer (CRC) metastasis. We aimed to clarify the roles of microRNAs (miRNAs) and their target genes in CRC stroma in the development of liver metastasis. METHODS: Tumour stroma was isolated from formalin-fixed, paraffin-embedded tissues of primary CRCs with or without liver metastasis by laser capture microdissection, and miRNA expression was analysed using TaqMan miRNA arrays. RESULTS: Hierarchical clustering classified 16 CRCs into two groups according to the existence of synchronous liver metastasis. Combinatory target prediction identified tenascin C as a predicted target of miR-198, one of the top 10 miRNAs downregulated in tumour stroma of CRCs with synchronous liver metastasis. Immunohistochemical analysis of tenascin C in 139 primary CRCs revealed that a high staining intensity was correlated with synchronous liver metastasis (P<0.001). Univariate and multivariate analyses revealed that the tenascin C staining intensity was an independent prognostic factor to predict postoperative overall survival (P=0.005; n=139) and liver metastasis-free survival (P=0.001; n=128). CONCLUSIONS: Alterations of miRNAs in CRC stroma appear to form a metastasis-permissive environment that can elevate tenascin C to promote liver metastasis. Tenascin C in primary CRC stroma has the potential to be a novel biomarker to predict postoperative prognosis.