Probe Development Summary for Inhibitors of HPGD (15-Hydroxyprostaglandin Dehydrogenase)
Eicosanoids are arachidonic acid derivatives that comprise distinct functional classes like prostaglandins (PGs), lipoxins and leukotrienes, and these bioactive fatty acids control a multitude of physiological functions including inflammation and differentiation. Dysregulation of the enzymes responsible for the generation and metabolism of active prostaglandins and lipoxins contributes to more ..
Eicosanoids are arachidonic acid derivatives that comprise distinct functional classes like prostaglandins (PGs), lipoxins and leukotrienes, and these bioactive fatty acids control a multitude of physiological functions including inflammation and differentiation. Dysregulation of the enzymes responsible for the generation and metabolism of active prostaglandins and lipoxins contributes to malignant transformation and progression in a variety of cancer types, such as breast, colon, lung and bladder cancers. The intracellular levels of prostaglandins are controlled mainly by the interplay between the cyclooxygenase enzymes (COX-1 and COX-2) on the one hand, and 15-hydroyxy-prostaglandin dehydrogenase (15 PGDH) and other inactivating enzymes on the other. COX-1 and -2 are bifunctional enzymes that, through their fatty acid cyclooxygenase- and prostaglandin (PG) hydroxyperoxidase activities, ultimately catalyze the generation of prostaglandin H2 (PGH2) from arachidonic acid. The other prostaglandins are then generated and transformed into one another by several isomerases and synthases, producing, e.g., prostacyclin (PGI2) or thromboxane A2 (TX). The wide variety of effects of prostaglandins in many different cell types is explained with binding to a variety of mainly G protein-coupled receptors of which eleven are currently known, but to some extent also to nuclear hormone receptors thus eliciting direct transcriptional effects.
15-PGDH represents the key enzyme in the inactivation of a number of active prostaglandins, leukotrienes and hydroxyeicosatetraenoic acids (HETEs) (e.g. by catalyzing oxidation of PGE2 to 15-keto-prostaglandin E2, 15k-PGE) . The human enzyme is encoded by the HPGD gene and consists of a homodimer with subunits of a size of 29 kDa. The enzyme was purified from human placenta and its primary structure determined by Edman degradation and was subsequently cloned and characterized. The enzyme belongs to the evolutionarily conserved superfamily of short-chain dehydrogenase/reductase enzymes (SDRs) and according to the recently approved nomenclature for human enzymes is named SDR36C1. Thus far, two forms of 15-PGDH have been identified, NAD+ dependent type I 15-PGDH and the type II NADP+-dependent 15-PGDH, also known as carbonyl reductase 1 (CBR1, SDR21C1). However, the preference for NADP+ and the high Km values of CBR1 for most PGs suggest that the majority of the in vivo activity can be attributed to type I 15-PGDH.
Several types of ligands for HPGD including activators and inhibitors, have been identified previously. These include clinically approved neuroactive drugs like imipramine and chlorpromazine that apparently activate the enzyme, and non-steroidal anti-inflammatory drugs (NSAIDs) and COX inhibitors, e.g. indomethacin, sulindac, and niflumic acid , or peroxisome proliferator-activated receptor gamma agonists such as thiazolidinediones, that weakly inhibit HPGD; potent HPGD inhibitors are lacking.
To identify novel high-affinity inhibitors that may be used to explore the biological function and intracellular interactions of 15-PGDH we performed a high-throughput screen (qHTS) of the MLSMR by using an in vitro enzymatic assay following the HPGD activity in real time kinetic mode by recording the fluorescence of the NADH cofactor reaction product.
This assay summarize the probe development and crystallization efforts that are currently ongoing.
Currently, 3 top probe compounds have been identified as inhibitors of HPGD (see bioassay data).
NIH Chemical Genomics Center [NCGC]
Structural Genomics Consortium [SGC]
Please see related AIDs for individual BioAssay additional details:
894, 2429, 2427
Please see PDB 2GDZ (MMDB 38442) for details on crystallization protocol.
Keywords: NIH Roadmap, MLPCN, MLI, MLSMR, qHTS, NCGC, SGC, HPGD
Compounds with HPGD_IC50 < 1uM were assigned a PUBCHEM_ACTIVITY_SCORE of 100.
** Test Concentration.
Data Table (Concise)