Treatment of Wistar rats with a renal carcinogen, ferric nitrilotriacetate, causes DNA-protein cross-linking between thymine and tyrosine in their renal chromatin.

Ferric nitrilotriacetate (Fe-NTA) induces renal proximal tubular damage associated with lipid peroxidation and oxidative DNA base modifications that finally leads to a high incidence of renal adenocarcinoma in rodents. In the present study, we report on the in vivo formation of DNA-protein cross-links (DPCs) involving thymine and tyrosine in the renal chromatin of Wistar rats treated with single or repeated i.p. administration of Fe-NTA. Analyses of chromatin samples by gas chromatography/mass spectrometry revealed a significant increase in the amount of 3-[(1,3-dihydro-2,4-dioxopyrimidin-5-yl)-methyl]-L-tyrosine (Thy-Tyr cross-link) 24 and 48 hr after the administration of Fe-NTA. At 19th day of Fe-NTA treatment, the amount of Thy-Tyr cross-link decreased to the control level, indicating the presence of cellular repair activity. Thy-Tyr cross-link may play a role in the genetic alteration of this renal carcinogenesis model, since mitoses for regeneration of renal proximal tubules were closely associated with the increase in DPCs.