Stromal VCAN expression as a potential prognostic biomarker for disease recurrence in stage II–III colon cancer

To develop prognostic biomarkers that can discriminate stage II–III colorectal cancer patients with high risk of postoperative recurrence, we conducted a genome-wide screening of relapse-related genes utilizing multiple microarray cohorts. Among differentially expressed genes between tumor and nontumor, we identified eight candidate genes associated with relapse in two datasets of stage II–III patients ( n = 94 and 145, respectively, P < 0.05). Using datasets of laser-microdissected samples and FACS-purified cell populations, the localization of candidate genes, including COL4A2, COL4A1, VCAN and SERPINE1, were found predominantly in cancer stroma rather than epithelial components. Among those relapse-related stromal genes, VCAN mRNA, specifically expressed in cancer-associated fibroblasts, was further validated to be a prognostic factor in two additional independent datasets, consisting of 453 ( P = 0.0334) and 89 ( P = 0.0041) stage II–III patients. Furthermore, in our large set of formalin-fixed paraffin-embedded cohort ( n = 338), VCAN protein was detected exclusively in cancer stroma by immunohistochemistry, demonstrating a stepwise increase of stromal VCAN from normal tissues through stage 0 to stage IV tumors. Stromal VCAN protein was associated with shorter relapse-free survival (RFS) in stage II–III colon cancer, independent of other clinical factors by multivariate analysis ( P = 0.004). Stratified analyses revealed that stromal VCAN was a strong prognostic indicator particularly in stage II colon cancer ( P = 0.0029). In all five analyzed cohorts, the expression of VCAN, in transcript or protein levels, was associated with poor RFS in stage II–III patients. We conclude that VCAN is a promising biomarker to identify stage II–III patients at high risk of relapse who may benefit from intensive postoperative management.