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Published on: May 12, 2019
Cohort study of COX-1 and COX-2 expression in canine rectal and bladder tumours
C Knottenbelt1, D Mellor, C Nixon
1Department of Veterinary Clinical Studies, Institute of Comparative Medicine, Faculty of Veterinary Medicine, University of Glasgow, Bearsden Road, Glasgow G61 1QH.
Objectives:
To determine the role that cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) play in malignant transformation in canine transitional cell carcinoma and rectal tumours.
Methods:
Histological sections of 21 canine rectal adenocarcinomas and 18 canine transitional cell carcinomas were stained for COX-1 and COX-2. Mann-Whitney non-parametric tests were applied to determine if there was any relationship between the percentage of cells expressing COX-1 or COX-2, and between COX-1 and COX-2 staining intensity and age, breed or sex.
Results:
For rectal adenocarcinomas, 19.0 per cent of the sections were negative for COX-1 and COX-2. A further 38.1 per cent of the sections were negative for COX-2 but positive for COX-1, and 38.1 per cent of the sections had rare or occasional single cells positive for COX-2. No significant differences were found in COX staining when compared with age, breed or sex. For transitional cell carcinomas, all of the sections were positive for COX-1 and COX-2. For COX-2 staining, 16.7 per cent had more than 30 per cent positive cells. For COX-1 staining, 38.9 per cent had more than 30 per cent positive cells. There was a significant increase in the percentage of COX-1 positive cells in small breed dogs (P = 0.0337).
Clinical Significance:
The variations in COX expression reported in this study may explain the differences in the clinical response of transitional cell carcinomas and rectal adenocarcinomas following treatment with non-steroidal anti-inflammatory drugs.
