LOX and LOXL2 Expression in Canine Mammary Carcinomas

Mammary tumours account for approximately 50% of the neoplasms in female dogs. Even conventionally accepted prognostic indicators often fail to reliably predict the clinical behaviour of these tumours, underscoring the need for more effective prognostic markers. Proteins of the LOX family are associated with tumour invasion and metastasis in several types of tumours. The purpose of this study was to characterise the immunohistochemical expression of LOX and LOXL2 in canine mammary carcinomas and to investigate their prognostic significance. Samples of mammary carcinomas from 80 female dogs with a minimum post-surgical follow-up of 180 days were analysed. Tumour samples were submitted to immunohistochemistry to detect LOX and LOXL2. Immunolabelling was evaluated based on scores for staining intensity and percentage of positive cells, and a combined score was used to classify each protein as having either 'low-' or 'high-expression'. The results were compared with histological types, mortality due to the disease and post-surgical survival. We found that negativity for LOXL2 expression was an indicator of higher risk of death due to the disease. Our results suggest that lysyl oxidases such as LOXL2 are potential prognostic markers in mammary carcinomas of dogs.