Enhanced stromal syndecan-1 expression is an independent risk factor for poor survival in bladder cancer

In this study, we assessed the changes and prognostic relevance of syndecan-1 (SDC1) tissue and serum levels in bladder cancer (BC). SDC1 levels were analyzed in 213 samples (119 paraffin-embedded and 79 serum samples of BC patients and 15 controls) using immunohistochemistry and enzyme-linked immunosorbent assay. Results were correlated with clinicopathological characteristics and follow-up data, as well as previously determined serum levels of angiogenic factors (basic fibroblast growth factor, endostatin, angiostatin, angiopoietin, vascular endothelial growth factor, Tie2 and MMP-7). SDC1 staining was present in the cell membrane of normal bladder epithelium and non-muscle-invasive BC cells but was absent in a significant proportion of muscle-invasive carcinomas (P < .001). In contrast, stromal SDC1 expression was enhanced in muscle-invasive compared to non-muscle-invasive BCs (P = .001). Serum concentrations of the SDC1 ectodomain were higher in muscle-invasive BCs compared to controls or non-muscle-invasive carcinomas (P < .001 each). Lymph node-positive cases had the highest SDC1 serum concentrations (P < .001). SDC1 expression in stromal cells was independently associated with survival (hazard ratio = 2.034, 95% confidence interval 1.176-3.519, P = .011). SDC1 serum concentrations correlated with those of endostatin and matrix metalloproteinase 7. Loss of SDC1 in tumor cells and the parallel increase of serum SDC1 ectodomain concentration in high-stage, high-grade BCs suggest the involvement of SDC1 shedding in BC progression. In addition, high preoperative SDC1 serum levels may help to identify patients with lymph node metastases, supporting therapeutic decision-making. Presence of SDC1 in tumor stroma is an independent risk factor for patient survival and may therefore be used to select patients for more aggressive therapy.