C-N-RAS IS ACTIVATED INFREQUENTLY IN CANINE MALIGNANT-LYMPHOMA

Activated c-N-ras alleles have been detected in human lymphoma specime ns. The aim of the present study was to determine the frequency of c-N -ras mutational activation in canine malignant lymphoma. DNA was isola ted from 28 canine malignant lymphoma specimens collected from 28 sepa rate dogs and examined for c-N-ras mutations by polymerase chain react ion amplification and direct sequencing. The tumors were naturally occ urring and derived from 20 dogs with known exposures to the phenoxy he rbicide 2,4-dichlorophenoxyacetic acid (2,4-D) and from 8 dogs with no known exposure to the herbicide. An oncogenically activating mutation was found in 1 dog without known 2,4-D exposure. The mutation was a 1 3th codon, second position transition that would result in a glycine-t o-aspartate amino acid substitution. The results of this study demonst rate that, similar to the human, c-N-ras mutations are uncommon in dog s with malignant lymphoma and that there is no association between 2,4 -D exposure and activation of c-N-ras in the dog.