NCAM and FGFR1 coexpression and colocalization in renal tumors

Neural cell adhesion molecule (NCAM) and fibroblast growth factor receptor (FGFR) have a role in epithelial-mesenchymal transformation during tumor genesis. Interplay between both molecules activates FGFR signaling and it could be responsible for tumor development. Renal epithelial tumors were analyzed for FGFR1 and NCAM coexpression by immunohistochemistry and for colocalization of these molecules on the particular tumor cells by triple immunofluorescence. Detection of NCAM isoforms in renal tumors was evaluated by RT-PCR. Applying immunohistochemistry we revealed that the majority of analyzed renal neoplasms, including renal cell carcinoma (RCC) and oncocytoma coexpressed NCAM and FGFR1. Triple immunofluorescent technique confirmed that both markers are commonly colocalized on the same tumor cells. Interestingly, it seemed that different position of NCAM and FGFR1 expression on renal tumor cells is related to renal tumor type or grade: exclusively membranous FGFR1/NCAM expression occurred in low grade clear cell RCC (cRCC); cytoplasmatic and membranous expression was present in high grade cRCC and other RCC types; oncocytoma showed only cytoplasmatic staining of both markers. NCAM-140 and NCAM-120 were detected in almost all analyzed renal neoplasms. Expression of both molecules on different cell compartments in various kidney tumors indicated that NCAM/FGFR1 interaction could play distinct roles in renal tumor genesis.