Mammaglobin as a diagnostic serum marker of complex canine mammary carcinomas

Mammaglobin is a glycoprotein exhibiting homology to uteroglobin gene family. Although the biological function of the protein is not yet known it has been reported to act as marker for breast cancer in women. This study reports the expression of mammaglobin gene in canine mammary tumor condition. The gene was cloned, sequenced and heterologously expressed in Escherichia coli host system as 12 kDa (approx.) recombinant fusion protein. The expressed protein was further purified to homogeneity and confirmed by western blotting. Hyperimmune sera were raised against the expressed protein in rabbits and mice to standardize sandwich ELISA for relative quantification of circulating protein in the sera of dogs with mammary tumors. Based on receiver-operating characteristics analysis, the test was found to be 90% sensitive and 95% specific for a cut-off value of 0.177 with respect to histopathological staining in diagnosing canine mammary tumors and the protein level was not elevated in other diseased conditions. These findings indicate that it can act as a novel molecular marker for detecting mammary tumors in canines.