Expression of Leptin and Leptin Receptor in Canine Mammary Tumors and Correlation with Obesity
Obesity is already considered as risk factor for mammary neoplasms in woman and female dogs. Leptin, a major protein that increases in concentration in obesity, may promote carcinogenesis of the mammary tissue through its interaction with the leptin receptor.
In the present study, we analyzed leptin and leptin receptor (ObR) expression in canine mammary carcinomas (CMC) by immunohistochemistry and correlated with body condition score (BCS) and age of the bitch, tumor size and histological grade. Tumor size, age and histological grade were also related with BCS.
The subjects were divided on the basis of their BCS: lean, optimal bodyweight, overweight or obese. Eighty-four bitches and ninety-five CMC specimens were randomly selected for the study.
Following microscopic examination, the samples were categorized as complex carcinomas (41% - 39/95) and simple carcinomas (59% - 56/95). Concerning the body condition score (BCS), 9.52% bitches were lean (8/84), 29.76% bitches had optimal bodyweight (25/84), 33.33% were overweight (28/84) and 27.39% bitches were obese (23/84) at the time of mastectomy. Obese animals presented mammary carcinomas at younger age and had larger tumors when compared to other body condition score (BCS). Leptin expression was not related to BCS; however, expression of ObR tended to be higher in tumors of bitches with higher BCS. Leptin expression was higher in older animals.
In conclusion, carcinomas of older animals expressed leptin and obese dogs presented mammary tumor at young age. Besides this, larger carcinomas presented higher ObR expression.