ESTABLISHED HUMAN RENAL-CELL LINES - PHENOTYPIC CHARACTERISTICS DEFINE SUITABILITY FOR USE IN INVITRO MODELS FOR PREDICTIVE TOXICOLOGY

The phenotypes of the human renal epithelial cell lines, SK-NEP-1 and G401 (Wilm's tumour lines) and ACHN, A498, A704, Caki-1 and Caki-2 (renal adenocarcinomas), were investigated in order to develop as toxicological model systems, human renal cell lines showing properties similar to those found in discrete renal tubular segments. All cell lines, except G401, demonstrated significant (P < 0.05) stimulation of adenyl cyclase activity by calcitonin. Alkaline phosphatase activity was not detectable in any cell line except for G401. None of the cell lines tested was capable of forming epithelial layers characteristic of 'tight' epithelia. The G401 cell line displayed several characteristics of the proximal nephron including a receptor for hPTH and detectable levels of the brush-border enzymes alkaline phosphatase (0.18 +/- 0.02 mU/mg protein), leucine aminopeptidase (14.0 +/- 5.1 mU/mg protein), glutathione transferase (8.61 +/- 2.53 mU/mg protein) and gamma-glutamyl transpeptidase (24.0 +/- 2.1 mU/mg protein). hPTH (0.01-1 muM) stimulated adenyl cyclase activity in homogenates of G401 cells in a dose-dependent manner, and this stimulation was reversed by 10 muM of the specific PTH antagonist Nle, Tyr-PTH 3-34 amide. The addition of 10 mum antagonist to unstimulated G401 cell homogenate reduced the basal activity of adenyl cyclase from 87.3 +/- 17.4 to 45.9 +/- 13.2 pmol cAMP/mg protein . 15 min. The effect of known nephrotoxic agents was tested on G401 cells by measuring basic mitochondrial enzyme function (MTT assay). The antibiotic gentamicin (5 mM), significantly (P < 0.001) inhibited MTT activity in a dose-dependent manner with a maximum inhibition to 23.2 +/- 9.2% of untreated G401 cells. S-(1,1,2,2,tetrafluoroethyl)-L-glutathione (4 mM) and its cysteine conjugate (2.5 mM) reduced MTT activity to 44.0 +/- 10.9% and 33.3 +/- 2.6% of control untreated G401 cells, respectively. We suggest that the G401 cell line may be a useful model of the human proximal tubule in predictive toxicology.