Prostaglandins

Definition

Prostaglandins are lipid compounds, which are synthesized from arachidonic acid. They are expressed in most tissues and participate in a wide array of physiologic activities but are also involved in the pathogenesis of various malignancies. Prostaglandin levels are regulated by the balance between their metabolism, which is mainly regulated by the cyclooxygenase (COX) enzyme, and their degradation, which is mainly regulated by the activity of the enzyme 15-hydroxyprostaglandin dehydrogenase (15-PGDH). Following their synthesis, the prostaglandins interact with specific G protein-coupled receptors and activate signaling pathways.

Characteristics

Biosynthesis

The first step in prostaglandin synthesis is the hydrolysis of arachidonic acid, by the enzyme phospholipase A2, from cell membrane phospholipids and the formation of free arachidonate (Fig. 1). The next two steps of prostaglandin synthesis are mediated by the COX enzymes. The cyclooxygenase activity of COX mediates the...