Correlation between MCM-3 protein expression and grade of malignancy in mammary adenocarcinomas and soft tissue fibrosarcomas in dogs.

BACKGROUND: Minichromosome maintenance proteins (MCM), due to their involvement in DNA replication in the course of mitosis, may provide sensitive markers of cell proliferation. Localization of MCM-3 and the extent of its expression were evaluated in mammary adenocarcinomas and soft tissue fibrosarcomas in dogs. The obtained results were compared to grades of malignancy (G) of the studied tumours. MATERIALS AND METHODS: The research material was sampled in the course of surgery in 71 dogs of various breeds, aged 4 to 14 years (50 cases of mammary adenocarcinoma and 21 cases of soft tissue fibrosarcoma). The tumours were verified by histopathology and immunohistochemistry was used to evaluate MCM-3 expression. The preparations were photographed and the images were subjected to computer-assisted image analysis using MultiScanBase Ver. 14.02 software. RESULTS: Nuclear expression of MCM-3 was detected in 70% adenocarcinomas and in over 71% of fibrosarcomas. Augmented expression of MCM-3 was observed in samples of tumours manifesting higher grade of malignancy. Statistical analysis demonstrated strong positive correlation (r=0.71 for fibrosarcomas, r=0.52 for adenocarcinomas; p<0.05) between MCM-3 expression and grade of malignancy in the studied tumours. CONCLUSION: MCM-3 may provide a sensitive and useful marker of proliferative potential in various histological types of neoplastic tumours.