Absence of ras Mutations and Low Incidence of p53 Mutations in Renal Cell Carcinomas Induced by Ferric Nitrilotriacetate

Abstract

Renal cell carcinomas induced in male Wistar rats by iron chelate of nitrilotriacetate (Fe‐NTA) were examined for mutations in ras oncogenes and p53 tumor suppressor gene. Fourteen primary tumors and two metastatic tumors from 11 animals were evaluated. Exons 1 and 2 of the H‐, K‐, and N‐ras genes were amplified by polymerase chain reaction (PCR), and the presence of mutations was examined by direct sequencing. Exon 5 through exon 7 of p53 gene, including the 3’half of the conserved region II and the entire conserved region III through V, were surveyed for point mutations by PCR‐single stranded conformation polymorphism (SSCP) analysis. Direct sequencing of the ras genes showed no mutations in codon 12, 13, or 61 among the tumors evaluated. SSCP analysis of p53 gene exon 6 indicated conformational changes in two primary tumors. One tumor had a CCG‐to‐CTG transition at codon 199, and the other had an ATC‐to‐ATT transition at codon 229 and two nonsense C‐to‐T transitions. These results suggest that neither ras genes nor p53 gene play a major role in the development of renal cell carcinomas induced by Fe‐NTA.