Federal University of Pará. Biological Science Institute. Molecular Biology Laboratory. Belém, PA, Brazil / Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Laboratório de Cultura de Tecidos e Citogenética. Ananindeua, PA, Brasil.Federal University of Pará. Biological Science Institute. Molecular Biology Laboratory. Belém, PA, Brazil.Federal University of Pará. Oncology Research Center. Belem, PA, Brazil.Federal Rural University of Amazonia. Health and Animal Production Institute. Animal Pathology Laboratory. Belém, PA, Brazil.Federal Rural University of Amazonia. Health and Animal Production Institute. Animal Pathology Laboratory. Belém, PA, Brazil.Ophir Loyola Hospital. Molecular Biology Laboratory. Belém, PA, Brazil / Federal University of Pará. Molecular Biology and Human Cytogenetics Laboratory. Belém, PA, Brazil.Federal University of Pará. Biological Science Institute. Molecular Biology Laboratory. Belém, PA, Brazil.Federal University of Pará. Biological Science Institute. Molecular Biology Laboratory. Belém, PA, Brazil.Background/Aim: In female dogs, mammary cancer is the most frequent cancer type, accounting for 50% of all tumors affecting these animals. Amongst the commonly altered genes in cancer is the cell-cycle regulator cyclin-dependent kinase inhibitor 2B (Cdkn2b), whose expression is negatively regulated by protein products of BMI1 proto-oncogene (Bmi1), MYC proto-oncogene (Myc) and T-box gene transcription factor 2 (Tbx2) genes. Considering this, the aim of this study was to evaluate the expression pattern of the Cdkn2b gene and these regulators in canine mammary tumors of dogs from Northern Brazil (Belém, Pará). Material and Methods: Gene expression in samples from 33 animals was assessed by real-time polymerase chain reaction. To check the influence of methylation on gene expression, bisulfite sequencing polymerase chain reaction was also performed. Results: All studied genes, except Cdkn2b, were found at increased expression levels in tumor tissue when compared with control samples. No correlation between expression and methylation data was observed. Conclusion: Our results suggest these markers may have a diagnostic value in the veterinary clinic
