Immunohistochemical study of permeability glycoprotein expression in canine perianal tumors

Abstract

Perianal gland tumors are common occurrences in dogs, originating from modified sebaceous glands located around the anus. Permeability Glycoprotein (PGP), a member of the ATP-binding cassette transporter family, plays a role in reducing intracellular drug concentration and limiting drug cytotoxicity in cancer cells. Although PGP expression has been identified in human and animal cancer cells, there are no reports on its expression in perianal gland tumors. Therefore, this study aimed to investigate PGP expression in perianal gland tumors. The incidence of perianal gland tumors in dogs presented to the Small Animal Hospital, Faculty of Veterinary Medicine, Chiang Mai University between 2015 and 2020 was examined. Sixty-four specimens from 64 dogs were histologically classified as perianal gland adenoma (59.38%), perianal gland epithelioma (12.50%), and perianal gland carcinoma (28.13%). The immunoreactive score results indicated four samples with a strong immunoreactive score (6.25%), comprising three samples from the carcinoma group and one sample from the adenoma group. Comparison of the immunoreactive scores among the three tumor groups using the Kruskal-Wallis test revealed a statistically significant difference (P=0.01219). Furthermore, pairwise comparisons employing the Wilcoxon rank sum test with continuity correction demonstrated a statistically significant distinction (P=0.015) between the adenoma and carcinoma groups.