Diamine oxidase activity in human tumors: Clinical and biologic significance

In the present review, we concentrate on the findings that the activity of the amine-metabolizing enzyme, diamine oxidase (DAO, EC 1.4.3.6-histaminase) is high in several types of human cancers. Investigators have been interested in the role of the synthesis and metabolism of amines in neoplastic tissues for many years. Although the specific functions of individual amines for mediation of tumor growth remain unknown, these agents could well play an important role in the proliferation and differentiation of neoplastic cells. For example, putrescine, the preferred in vivo substrate for DAO, is an amine whose synthesis is closely regulated during growth and differentiation. 1, 2 Pools of this amine provide the substrate for the biosynthesis of the polyamines, spermidine and spermine, which may be essential for the rapid growth of normal and neoplastic cells. 1, 2 Thus, the metabolism of putrescine could play an obvious potential role in regulation of the quantities of these molecules, and could then be important to the growth of cancer cells. Similarly, levels of metabolizing enzymes for different amines could be clinically useful as tumor biomarkers.