HK-2 - AN IMMORTALIZED PROXIMAL TUBULE EPITHELIAL-CELL LINE FROM NORMAL ADULT HUMAN KIDNEY

Studies assessing mechanisms of proximal tubular cell (PTC) physiology and pathophysiology increasingly utilize cell culture systems to avoi d the complexity of whole organ/whole animal experiments. However, no well-differentiated PTC line derived from adult human kidney currently exists. Therefore, the goal of this research was to establish such a line by transduction with human papilloma virus (HPV 16) E6/E7 genes. A primary PTC culture from normal adult human renal cortex was exposed to a recombinant retrovirus containing the HPV 16 E6/E7 genes, result ing in a cell line designated HK-2 (human kidney-2) which has grown co ntinuously in serum free media for more than one year. HK-2 cell growt h is epidermal growth factor dependent and the cells retain a phenotyp e indicative of well-differentiated PTCs (positive for alkaline phosph atase, gamma glutamyltranspeptidase, leucine aminopeptidase, acid phos phatase, cytokeratin, alpha3beta1 integrin, fibronectin; negative for factor VIII-related antigen, 6.19 antigen and CALLA endopeptidase). Fu rthermore, HK-2 cells retain functional characteristics of proximal tu bular epithelium (Na+ dependent/phlorizin sensitive sugar transport; a denylate cyclase responsiveness to parathyroid, but not to antidiureti c, hormone). The E6/E7 genes are present in the HK-2 genome, as determ ined by PCR. To assess its potential usefulness as a tool for studying injury and repair, HK-2 cells were exposed to a toxic concentration o f H2O2 +/- iron chelation (deferoxamine) or hydroxyl radical scavenger (Na benzoate) therapy. Only the former blocked H2O2 cytotoxicity, rep roducing results previously obtained with freshly isolated rat proxima l tubular segments. In conclusion, an immortalized adult human PTC lin e has been established by transduction with HPV 16 E6/E7 genes. It app ears to be well-differentiated on the basis of its histochemical, immu ne cytochemical, and functional characteristics, and it can reproduce experimental results obtained with freshly isolated PTCs. Thus, this n ew PTC line could have substantial research application.