Extracellular proteases in renal cell carcinoma.

Abstract

363 Background: Tumor growth and metastasis relies on extracellular matrix remodeling, which is primarily mediated by the matrix metalloproteinase (MMP) family of enzymes. Extracellular matrix metalloprotease inducer (EMMPRIN, E) is a glycoprotein also implicated in tumor progression and has been shown to function in concert with MMPs. MMPs and E are highly expressed on the surface of many malignant tumors, including renal cell carcinoma (RCC). We investigated whether MMPs and E represent molecular prognostic factors in RCC. Methods: Protein expression was evaluated in 77 patients with immunohistochemical analysis of a tissue microarray (TMA) consisting of two tumor samples and an adjacent normal renal sample from each patient. Tumors represented on the TMA were clear cell (57), chromophobe (9), papillary (4), oncocytomas (3), clear cell with sarcomatoid differentiation (2), and metastatic (2). Protein expression scores were correlated with clinical outcomes to determine prognostic significance by univariate and multivariate analyses. Results: Using univariate analysis of all RCC tumors, membranous E correlated with overall survival (OS), metastasis-free survival (MFS), size, stage and overall 5-yr survival. Cytoplasmic E correlated with OS, MFS, size, grade, stage and 5-yr survival. Membranous MT1-MMP correlated with MFS, and endothelial MMP-2 correlated with grade. In multivariate analysis, membranous E was an independent indicator of stage, whereas cytoplasmic E was an independent indicator for size, stage, grade and MFS. In the clear cell population, membranous MT1-MMP correlated with OS and MFS, and endothelial MMP-2 correlated with grade in univariate analysis. In multivariate analysis, membranous MT1-MMP was an independent indicator for MFS. Conclusions: We identified EMMPRIN as an independent prognostic indicator for size, grade, stage, and MFS in RCC. While MT1-MMP and MMP-2 both significantly correlated with disease outcome in the clear cell RCC population, only MT1-MMP was an independent prognostic factor for MFS. We conclude that MMPs and E mediate important steps in RCC progression. Further investigation is warranted using larger datasets and a prospective study to determine the strength of the prognostic significance of these findings. No significant financial relationships to disclose.