Veterinary oncology is very important nowadays to get a better understanding of human carcinogenesis. Estrogen receptor, progesterone receptor and Human Epidermal Growth Factor receptor 2 are frequently evaluated by immunohistochemistry (HIC) in human breast tumor. WT1 is an oncogene, its overexpression has been detected in leukemia and diverse solid tumors like breast cancer, lung cancer and mesothelioma in humans. WT1 expression was evaluated in 15 canine breast tumors (CBT) diagnosed by histopathological analysis to find its relationship with neoplasia and malignancy. IHC and RT-PCR were performed in CBT tissues. Fisher ́s test was used to analyze WT1 relationship with malignancy. Of the 15 tumors, 9 (60 %) were diagnosed as benign and 6 (40 %) were malignant. With IHC, WT1 expression was positive only in biopsies diagnosed as malignant. Expression of WT1 by RT-PCR was detected in 14 of the 15 tumors (93.33 %) as well as in control healthy mammary gland. Clinical significance: This study describes for the first time a close correlation between CBT and a positive result for WT1 expression with IHC; hence, it can be used as a biomarker for this neoplasia and as an indicator of malignancy. RT-PCR analysis also showed to be good option to detect WT1 expression. These results will be useful to further investigations to elucidate WT1-related signaling pathways in CBT. Also to know molecules that regulate the translation of this protein as a marker for tumor progression.

KEY WORDS: Canine Breast Tumor; WT1; Histological type; Malignancy; Immunohistochemistry.

CARRANZA-MARTÍNEZ, B. D.; SALAS-TREVIÑO, D.; SOTO-DOMÍNGUEZ, A.; RAMÍREZ-ROMERO, R.; ZAPATA-BENAVIDES, P.; CEDILLO-ROSALES, S.; ZÁRATE-RAMOS, J. J.; SAUCEDO-CÁRDENAS, O. & ZAMORA-ÁVILA, D. E. WT1 expression as a potential biomarker of malignancy in canine breast tumor. Int. J. Morphol., 37(1):190-195, 2019.