Metallothionein immunostaining as a prognostic indicator in canine mammary tumours

Research on metallothionein (MT) has been traditionally focused on its role in metal homeostasis and toxicity [1]. In recent years, the role of MT in carcinogenesis [2] and its potential applications differentiating malignant from benign neoplasms has received increased attention. Metallothionein is elevated in ovarian neoplastic cells [3] and its over expression in some cancer cell lines has been found to confer resistance to chemotherapy [4, 5, 6]. Increased expression of MT has been described in some types of human cancer including thyroid carcinomas [7], malignant melanomas [8] and mammary cancer [9, 10, 11, 12, 13, 14]. In human breast cancer studies, tumours with a better prognosis had lower levels of MT expression than those tumours with a less favourable prognosis [9, 10, 11, 13, 14].