Expression of AKR1C3 in renal cell carcinoma, papillary urothelial carcinoma, and Wilms' tumor.

Human aldo-keto reductase (AKR) 1C3 is a monomeric cytoplasmic multifunctional enzyme that reduces ketosteroids, ketoprostaglandins, and lipid aldehydes. AKR1C3 was initially identified as an enzyme involved in steroid metabolism. However, immunohistochemistry has demonstrated AKR1C3 in normal adult kidneys with expression in Bowman' capsule, the mesangial cells, proximal and distal tubules, as well as mature urothelial epithelium. The significance of its spatial distribution and metabolic activities in the kidney remains undefined. In addition to its ability to catalyze steroid hormones (including androgen, desoxycorticosterone, and progesterone) and involvement in prostaglandins metabolism, we suspect that AKR1C3 may function as a chemical barrier in the renal tubules for normal function in mature kidneys. Moreover, AKR1C3 may represent a developmental marker for some urological epithelial tissues. In this study, we demonstrate widespread expression of AKR1C3 in renal neoplasms with a phenotype recapitulating mature kidney (i.e., renal cell carcinoma) and urothelium also known as transitional epithelium (i.e., papillary urothelial carcinoma), but noted limited AKR1C3 expression in renal neoplasms with a phenotype recapitulating embryonic kidneys (i.e., Wilms' tumor). Our results suggest that AKR1C3 may represent a developmental marker that is related to renal epithelium maturity.