Ki‐ras Activation in Pancreatic Carcinomas of Syrian Hamsters Induced by N‐Nitrosobis(2‐hydroxypropyl)amine

Five pancreatic carcinomas induced by N‐nitrosobis(2‐hydroxypropyl)amine in Syrian golden hamsters were analyzed for activation of Ki‐ras at codons 12 and 13, using the polymerase chain reaction and direct sequencing. The Ki‐ras gene was shown to be activated in four of the five carcinomas, and the results were further confirmed by subcloning and sequencing. All the mutations involved a G‐to‐A transition at the second position of codon 12, which resulted in a change at the amino acid level from glycine to aspartic acid. This mutation is identical with that reported for pancreatic tumors of Syrian hamsters induced by N‐nitrosobis(2‐oxopropyl)amine.