ENDOPEPTIDASE-24.11 CD10 IS DOWN-REGULATED IN RENAL-CELL CANCER

The regulatory mechanisms responsible for malignant transformation, tu mor progression and metastasis in renal cell cancer (RCC) are still un clear, but there is some evidence that biologically active peptides mi ght have regulatory effects on the behavior of this malignancy. Tumor cells can change local concentrations of active peptides by modulating their cell-surface enzymes. Using immunohistochemistry and enzyme-his tochemistry, the expression of various membrane peptidases was examine d in RCC and adjacent noninvaded renal parenchyma (n=44)We describe th e down-regulation of neutral endopeptidase 24.11 (NEP) protein express ion in RCC of the clear cell/chromophilic type when compared with rena l parenchyma, and show for the first time the lack of enzyme activity of NEP in RCC. The strongest expression could be found for dipeptidyl peptidase IV (DPIV) which is only decreased in RCC of the chromophobe cell type and is even present in oncocytoma. Aminopeptidase N (APN) an d aminopeptidase A (APA) show attenuated expression in up to one third of clear cell/chromophilic RCC. Chromophobe RCC and oncocytomas do no t express APN, APA, NEP and gamma-glutamyltranspeptidase.