HER-2 and ERa Expression in Canine Mammary Carcinomas

Maria Kern, Vassar College ’11, Catharine Varnum, Vassar College ’10 with Prof. David K. Jemiolo and Joseph A. Impellizeri DVM ACVIM

PCR primers were developed to study the involvement of HER-2 and ERα in canine mammary tumors using human studies as guides. In humans, overexpression of either HER-2 (human epidermal growth factor receptor) or ERα (estrogen receptor) is frequently associated with mammary tumors but the involvement of these genes in canine tumors is unknown. The canine HER-2 primers bind in adjacent exons and produce a 195 bp amplicon from HER-2 mRNA. This amplified region codes a transmemembrane domain. The primers also amplify genomic DNA producing a 292 bp amplicon. This dual-priming ability allows for the detection of contaminating genomic DNA in cDNA derived from tumor RNA. ERα primers were also developed to measure mRNA levels. The gene for ERα contains seven large introns. The primers bind in adjacent exons separated by a long intron. Therefore, the genomic DNA template is too large to amplify efficiently. The ERα primers produce a 168 bp amplicon from mRNA that codes for the estrogen-binding site. The HER-2 and ERα primers were tested on genomic DNA from dog blood and on RNA isolated from dog uterus. Both primer pairs produced the appropriate products. We confirmed that the 168 bp ERα product is the correct amplicon by restriction endonuclease analysis.

* Veterinary Specialty Center of the Hudson Valley, Wappingers Falls, NY