Altered oxidant-antioxidant profile in canine mammary tumours.

Mammary tumours are the most common neoplasms in female dogs. Oxidative stress arising due to overproduction of reactive oxygen species, coupled with altered antioxidant capacities has been implicated in the pathogenesis of all types of cancers. However, the extent of lipid peroxidation and the status of antioxidants in canine mammary tumours have not been investigated. The present study was designed to evaluate the oxidant-antioxidant profile in canine mammary tumours. Lipid peroxidation as evidenced by the formation of thiobarbituric acid-reactive substances, lipid hydroperoxides, and conjugated dienes, as well as the status of the antioxidants superoxide dismutase, catalase, reduced glutathione, glutathione peroxidase, glutathione S-transferase and vitamin C, in tumour tissues of 25 bitches was estimated. Lipid peroxidation in tumour tissues was enhanced compared to the corresponding adjacent uninvolved tissues. This was accompanied by significant elevation in both enzymatic and non-enzymatic antioxidants. This study suggests that upregulation of antioxidants induced by lipid peroxidation confers a selective growth advantage to tumour cells over their adjacent normal counterparts.