Expression of survivin mRNA in dog tumors.

Survivin, a member of the inhibitor of apoptosis (IAP) gene family, overexpresses in various human tumors. Recently this protein has attracted strong interest as a potential prognostic marker because it promotes malignancy through anti-apoptotic activity and is associated with a more aggressive phenotype. To explore the utility of survivin as a veterinary marker of tumor malignancy, we performed molecular cloning of dog survivin cDNA and studied survivin mRNA expression in a variety of naturally occurring dog tumors. The dog cDNA contains a 426-bp open reading frame encoding 142 amino acids of polypeptide, in which a structure termed the baculovirus IAP repeat (BIR) domain, commonly observed in IAPs, is found, as it is in other mammalian survivin protein. The transcript was detected in many adult normal organs including heart, lung, liver, stomach, duodenum, colon, spleen, kidney and testis. As a result of quantitative expression analysis by real-time PCR undertaken for benign and malignant tumors, overexpression of the survivin gene was found in 3 of 18 malignant tumors and in none of the benign tumors, suggesting that survivin overexpression is associated with tumor malignancy in dog.