Osteopontin Expression and Its Prognostic Significances in Human Renal Cell Carcinoma

ABSTRACT

BACKGROUND: Osteopontin (OPN) is a glycoprotein and it participates in cell-cell and cell-matrix interactions. In vitro studies suggest that the OPN expression is associated with tumor metastasis, and especially with the metastasis of osteotropic tumors originating in breast, prostate and lungs. Since no human tissue study has suggested the means by which OPN participates in the tumorigenesis, angiogenesis, progression and metastasis of renal cell carcinoma (RCC), we evaluated the expression and prognostic significance of OPN in RCC. METHODS: Immunohistochemistry was performed with using the primary antibody for OPN on the archival paraffin-embedded tissue microarray specimens from 51 RCC patients who underwent radical or simple nephrectomy. RESULTS: In the normal kidney specimens, OPN was expressed in a few compressed distal tubules adjacent to the RCCs. In RCCs, the OPN expression was elevated in larger tumors (p<0.05) and in the tumor with low microvessel density (p<0.01). In the present study, univariate analysis indicated that stage, tumor size, lymph node and distant organ metastasis are significant prognostic factors for disease free survival (DFS) in RCC patients (p<0.01), but OPN is not (p=0.0661). Multivariate analysis indicated lymph node metastasis is the independent prognostic indicator of DFS (p<0.05). CONCLUSION: Though this study has statistical limitations, these results suggest OPN plays a role in tumor progression and metastasis and it may act as a potential prognostic indicator to predict the prognosis of RCC patients.