Role of the human cytochrome b561 family in iron metabolism and tumors (Review).

The human cytochrome b561 (hCytb561) family consists of electron transfer transmembrane proteins characterized by six conserved α-helical transmembrane domains and two β-type heme cofactors. These proteins contribute to the regulation of iron metabolism and numerous different physiological and pathological processes by recycling ascorbic acid and maintaining iron reductase activity. Key members of this family include cytochrome b561 (CYB561), duodenal CYB561 (Dcytb), lysosomal CYB561 (LCytb), stromal cell-derived receptor 2 (SDR2) and 101F6, which are widely expressed in human tissues and participate in the pathogenesis of several diseases and tumors. They are associated with the promotion or inhibition of tumor growth and progression in various malignancies and are potential therapeutic targets for malignant tumors. The present review summarizes the existing literature regarding the structure of the Cytb561 family, the basic functional characteristics of hCytb561 family members, and the roles of the CYB561, Dcytb, LCytb, SDR2 and 101F6 in various diseases and tumors.