Melanotransferrin: Search for a function

Melanotransferrin was discovered in the 1980s as one of the first melanoma tumour antigens. The molecule is a transferrin homologue that is found predominantly bound to the cell membrane by a glycosyl-phosphatidylinositol anchor. MTf was described as an oncofoetal antigen expressed in only small quantities in normal tissues, but in much larger amounts in neoplastic cells. Several diseases are associated with expression of melanotransferrin, including melanoma and Alzheimer's disease, although the significance of the protein to the pathogenesis of these conditions remains unclear. In this review, we discuss the roles of melanotransferrin in physiological and pathological processes and its potential use as an immunotherapy. Although the exact biological functions of melanotransferrin remain elusive, a growing number of roles have been attributed to the protein, including iron transport/metabolism, angiogenesis, proliferation, cellular migration and tumourigenesis. The high expression of melanotransferrin in several disease states, particularly malignant melanoma, remains intriguing and may have clinical significance. Further studies on the biology of this protein may provide new insights as well as potential therapeutic avenues for cancer treatment. This article is part of a Special Issue entitled Transferrins: Molecular mechanisms of iron transport and disorders.