Genetic Characterization and Expression Analysis of Recombinant Manganese Superoxide Dismutase (MnSOD) from Spontaneously Occurring Canine Mammary Tumor

Cancer onset typically encompasses alterations in cellular proliferation, production of reactive oxygen species (ROS), and DNA damage. Manganese superoxide dismutase (MnSOD) is one of the key enzymes for controlling oxidative stress. The role of MnSOD in cancer development is complex. Although initially considered as a tumour suppressor protein, recently it has been looked upon as a potential marker for cancer metastasis. Though MnSOD has been studied extensively in human cancers, not much work has been done for elucidating its role in dog cancers. Further dog MnSOD gene has not been sequenced so far, although dog MnSOD gene sequence predicted using computational biology approaches is present in the GenBank database. Therefore in this study, full-length ORF of sod2 gene, a gene encoding MnSOD enzyme, from a case of canine mixed mammary capillary cystic adenocarcinoma was cloned and sequenced. The sequence showed 100% similarity with the predicted dog MnSOD sequence present in GenBank database based on computational algorithms. Comparison of deduced amino acid sequence from Canis lupus familiaris and Homo sapiens revealed 92% similarity, confirming the conserved nature of the protein. Further the full-length MnSOD was expressed in E.coli and purified protein was isolated successfully. The recombinant MnSOD from dog offers a new tool for studying effect of the anti-oxidant enzyme on dog cancer cells, wound healing and other disorders.