Cyclooxygenase-2 expression is associated with histologic tumor type in canine mammary carcinoma.
Cyclooxygenase-2 (COX-2) is an inducible member of the family of cyclooxygenase enzymes that has been implicated in the genesis of numerous cancers. The role of COX-2 in canine mammary neoplasia remains to be more clearly elucidated. The goal of the study reported here was to determine whether a direct association between levels of COX-2 expression and tumor histologic subtype exists in canine mammary carcinoma. Immunohistochemical analysis was performed using a polyclonal antiprostaglandin G/H synthase 2 IgG COX-2 antibody. Sections from the kidneys of young dogs, which stain positive for COX-2 in the macula densa, served as positive controls. Slides were reviewed by a single pathologist, and were evaluated for COX-2 expression according to previously established scales. Positive-staining tumors were given a COX-2 staining distribution (on the basis of the percentage of positive staining cells in five 400x fields) and intensity score according to previously established scales. The product of the COX-2 staining distribution and intensity scores was calculated to create a COX-2 staining index. COX-2 expression was detected in 28 of 50 (56%) samples evaluated. Anaplastic carcinomas had a significantly higher COX-2 staining distribution, intensity, and index, compared with those for adenocarcinomas (P < 0.0001). The overall percentage of positive tumors (56%) was consistent with that of prior studies. To the authors' knowledge, these results indicate, for the first time, a direct association between COX-2 expression and tumor histologic subtype in canine mammary carcinomas. Future research directed at measuring tumor response in canine mammary carcinoma patients treated with a selective COX-2 inhibitor is indicated.
Heller
D A
DA
Department of Clinical Studies, Matthew J. Ryan Veterinary Hospital of the University of Pennsylvania, 3900 Delancey Street, Philadelphia PA 19104, USA.
Clifford
C A
CA
Goldschmidt
M H
MH
Holt
D E
DE
Shofer
F S
FS
Smith
A
A
Sorenmo
K U
KU
D000230:Adenocarcinoma / Q000201:enzymology / Q000662:veterinary*; D000818:Animals; D002277:Carcinoma / Q000201:enzymology / Q000662:veterinary*; D051546:Cyclooxygenase 2 / Q000378:metabolism*; D004283:Dog Diseases / Q000201:enzymology*; D004285:Dogs; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D007150:Immunohistochemistry / Q000662:veterinary; D015674:Mammary Neoplasms, Animal / Q000201:enzymology*
D051546:Cyclooxygenase 2