Investigation of HER2 expression and apoptotic mechanisms in naturally occurring mammary tumors in dogs

Canine mammary tumors have clinical, pathological, prognostic significance for dogs as these pets share the same conditions as humans, genetically related to human breast cancers, and mammary tumors have increased frequency in veterinary medicine. Difficulties for both animal owners and clinicians in the formation, development and diagnosis that will shape the future prognosis and treatment of canine mammary tumors include the type, aggressiveness and treatment of the tumor. For this purpose, 42 mammary biopsy materials were examined histopathologically and immunohistochemically, and tumor-specific lesions were identified, and it was aimed to investigate the pathogenesis, apoptosis and HER2 of benign and malignant canine mammary tumors. The tumor samples were examined histopathologically, apoptotic index was determined by TUNEL method and caspase-3, -8, -9 and HER2 expressions were evaluated semi-quantitatively by immunohistochemical method. Histopathologically, 36 of the tumors were classified as adenocarcinoma and 6 were classified as adenoma and benign changes. Malignant tumors were classified as tubular carcinoma, complex carcinoma, carcinoma mixed type, carcinoma and malignant myoepithelioma, carcinosarcoma, ductal carcinoma, intraductal papillar carcinoma, anaplastic carcinoma, solid carcinoma and comedocarcinoma. Positive reactions with varying localization and severity related to caspase-3, -8, -9, HER2 expression were determined immunohistochemically. TUNEL reactions were mild positive or negative in benign mammary tumors, whereas positive reactions were detected in malignant epithelial cell nuclei in malignant tumors. Variations in apoptotic mechanisms determined in malign mammary tumors have been associated with genetic diversity that plays a role in both oncogenesis and apoptosis. Studies including cell growth, transcription, mutations and expression analysis should be conducted in addition to pathological research in canine mammary tumors. HER2 immunopositivity, which is important for prognosis and survival in human breast cancers, was approximately 1 in 5 in study cases and when compared with human cases, it has been revealed that this information will gain meaning with different studies to be conducted with healthy survival records.