Analysis of p53 mutational events and MM2 amplification in canine soft-tissue sarcomas

Canine cancer is of major significance in terms of animal health and welfar e and soft tissue sarcomas are an important group of tumours accounting for approximately 15% of all canine tumours presented. Abnormal p53 protein ex pression and gene mutations have been identified in a number of different c anine tumour types. However, mdm2 gene amplification has only been investig ated in a limited number of canine osteosarcomas. In this present study a s eries of canine soft-tissue sarcomas (STS) were examined for p53 mutations and/or mdm2 amplification. For p53 mutational studies polymerase chain reac tion and direct DNA sequencing was used. Gene mutations were identified in 6 of 30 (20%) primary tumour cases including MPNST (n = 3) leiomysarcoma (n = 1), heamangiosarcoma (n = 1) and sarcoma (n = 1). mdm2 gene amplificatio n was assessed by Southern Blot. Although there was no evidence for major g ene rearrangements, gene amplification was detected in 4 of 35 (11.4 %) pri mary tumours including NMNST (n = 2), rhabdomyosarcoma (n = 2). A total of 33 cases were examined for both p53 mutations and mdm2 amplification. Seven of the tumours were positive for p53 mutations, while five were positive f or mdm2 amplification. With the exception of one case, a reciprocal relatio nship between the presence of a p53 mutation and mdm2 gene amplification wa s demonstrated. (C) 2001 Published by Elsevier Science Ireland Ltd.