CYTOGENETIC ALTERATIONS IN 8 MAMMARY-TUMORS AND TUMOR-SUPPRESSOR GENEP53 MUTATION IN ONE MAMMARY-TUMOR FROM DOGS

Objective-To identify mutations in canine mammary tumors. Animals-10 t umor-bearing dogs. Procedure-Culture of neoplastic cells originating f rom mammary tumors was performed, and trypsin-G banding was used for c ytogenetic investigations. The same tumors were subjected to molecular genetic screening by use of DNA extraction, polymerase chain reaction , DNA elution, and DNA sequencing for ras oncogenes and the p53 tumor suppressor gene. Results-A broad spectrum of chromosome aberrations wa s observed, including trisomies, reciprocal translocations, and struct ural and numerical X-chromosome alterations and deletions. Molecular g enetic analysis revealed a tumor suppressor p53 gene mutation in codon 249 of exon 7 in one instance. Interestingly, analyzed mammary tumors were free of mutations in N-ras, K-ras and H-ras, exons 1 and 2. Conc lusions-Chromosome alterations are widespread in canine mammary tumors , but no ras family mutations were detected in tumors from these 10 do gs. Clinical Relevance-Knowledge about chromosome, oncogene, and tumor suppressor gene damage could be helpful for diagnosis and prognosis o f neoplastic diseases in dogs.