Expression of caveolin-1 in renal neoplasms

14509 Background: Caveolin-1 is the major structural and functional component of caveolae, which are specialized lipid raft microdomains on cell membrane important for signaling pathways related to cell adhesion, growth and survival. Studies have shown that clear cell renal cell carcinoma (CCRCC) expressed caveolin-1 and that the over-expression correlated with adverse pathological findings and poor outcomes. The expression of caveolin-1 in other types of renal tumors has not been studied. Methods: A tissue microarray (TMA) was constructed from 60 normal kidneys, 22 CCRCC, 20 papillary renal cell carcinomas (PRCC), 16 chromophobe renal cell carcinomas (ChRCC), and 19 oncocytomas (ONC). The TMA was immunostained for caveolin-1 protein. Membranous caveolin-1 expression was scored using the internal vascular endothelial cells as positive control. Results: Membranous caveolin-1 expression was detected in 19/22 (86.4%) CCRCC, in 1/20 (5%) PRCC, 0/16 (0%) ChRCC, and 1/19 (5.3%) ONC. Cytoplasmic caveolin-1 was detected in 16/22 (72.7%) CCRCC, 13/20 (65%) PRCC, 8/16 (50%) ChRCC and 13/19 (68.4%) ONC. Membranous caveolin-1 expression correlated with tumor size (Pearson correlation = 0.266, p = 0.043). There was no correlation between membranous or cytoplasmic caveolin-1 expression and other pathological parameters, including Fuhrman nuclear grade, or TNM stage. Conclusion: Caveolin-1 exhibits distinct subcellular localization in different renal tumors. Membranous caveolin-1 is most commonly detected in CCRCC, rarely found in PRCC and ONC, and is absent in ChRCC. This finding suggests that caveolin-1 may play an important role in the pathogenesis of CCRCC. [Table: see text]