Localization of urotensin-II immunoreactivity in normal human kidneys and renal carcinoma.

Human urotensin-II (U-II) is a cyclic 11-amino-acid residue peptide with a wide range of vasoactive properties dependent on the anatomic site and the species studied. The purpose of this study was to determine the localization of human U-II in normal human kidneys and in renal carcinoma. Normal human kidneys (n=11) and eight cases of clear-cell carcinoma were immunostained with a polyclonal antibody to human U-II. In normal human kidneys, U-II was mostly present in the epithelial cells of tubules and ducts, with greater intensity in the distal convoluted tubules. Moderate U-II immunoreactivity was seen in the endothelial cells of renal capillaries, but only focal immunoreactivity was found in the endothelial cells of the glomeruli. No staining was found in the veins. All tumors expressed moderate U-II immunoreactivity in the cancer cells and vasculature. Here we demonstrate abundant expression of U-II in normal human kidneys and renal carcinoma. These findings suggest that the vasoactive and growth-mediator peptide U-II may contribute to the pathophysiology of the human renal system.