Human serum steroid-binding proteins and malignancy (review)

Many steroid-binding proteins are normal constituents of human serum. They regulate the bioavailability of steroid hormones to receptors in target tissues, either by preventing the availability of unbound steroids, or by delivering them into cells, depending on the binding protein or the tissue considered. In this review three models describing these situations and a tentative unifying concept for the various possible roles of the steroid-binding proteins are presented. In some malignant situations, the serum concentrations of the normal steroid-binding proteins are modified, and in some cases some abnormal steroid-binding proteins appear in the serum. These situations seriously modify the normal steady state of steroid hormone delivery to target cells and might consequently play an important role in the development of these diseases.