Evaluation of galectins 1 and 3 expression in canine melanoma

Abstract

Canine melanoma is a frequently-occuring neoplasm in dogs and presents as malignant and highly metastatic in this context, studies that contribute to the understanding of the tumor microenvironment in melanoma include the role of galectins. Galectins are proteins of the family of animal lectins that display carbohydrate recognition domains. Galectin-1 and galectin-3 are associated with neoplastic transformation, neoplastic cell survival, angiogenesis, immune system evasion, and metastasis. The goal of this study was to establish a correlation between expression patterns of galectin-1 and galectin-3 and the different degrees of aggressiveness of canine melanoma, as well as to determine serum concentration of galectin-3 in dogs with melanoma. Galectin-1 and galectin-3 expression was analyzed by immunohistochemistry in 30 canine melanomas, six melanocytomas and nine metastatic lymph nodes from patients whose primary tumors were also processed and analyzed. Serum samples from 30 dogs were collected and galectin-3 concentration was determined by ELISA and compared to the samples of 10 healthy dogs. Canine melanoma samples expressed galectin-1 in the cytoplasm and presented a variable pattern of galectin-3 staining depending on melanoma aggressiveness. We observed a decrease in the percentage of cells with cytoplasmic galectin-3 immunolabeling simultaneous to the increased nuclear staining intensity, while there was also a decrease in the percent frequency of nuclear galectin-3 immunolabeled cells according to progression of melanoma, comparing the least to the most aggressive cases. Dogs with melanoma had increased serum levels of galectin-3 when compared to healthy animals, suggesting its potential biomarker of patients with melanoma.