Expression of BCL2 associated athanogene-1 is up-regulated in canine malignant mammary tumors

Mammary tumors are frequently seen in female dogs. Conventionally, these tumors are diagnosed by histopathology. Differentially expressed biomarkers could aid in more specific diagnosis of the malady. BCL2 associated athanogene-1 (BAG1) inhibits apoptosis and promotes tumor growth, contributing to therapeutic resistance, thus serving as a potential prognostic biomarker in cancer. The present investigation focuses on assessing the expression of BAG-1 in different histotypes of canine mammary tumors (CMT). CMT tissues were collected after surgery and were classified into complex carcinomas, malignant mixed mammary tumors, anaplastic carcinoma, and intraductal papillary carcinoma and majority of them belonged to Grade II. BAG-1 mRNA was found to be up-regulated in canine mammary tumors by SYBR green based real time-PCR. Further, gene encoding immuno-dominant region of BAG-1 was cloned and expressed in a prokaryotic system. Upon purification, a 42KDa fusion protein was obtained which was confirmed by Western blotting. Hyperimmune serum was raised against the protein in mice to standardize immunohistochemistry to assess expression of this protein in canine mammary tumors. A strong expression of BAG-1 was seen in a majority of these tumors. A positive correlation between BAG-1 mRNA and BAG-1 protein expression was also observed in various histotypes of CMT.