The Role of Glycosylation in the Efficacy of Cyclooxygenase‐2 Inhibitors

Abstract

Cyclooxygenase‐2 (COX‐2) is an enzyme that catalyzes the rate‐limiting step in the prostanoid synthesis pathway, which plays an important role in a variety of physiological and pathophysiological processes including inflammation and cancer. COX‐2 exists as two major glycoforms of 72 and 74kDa, the latter resulting from an additional oligosaccharide chain at amino acid residue Asn580. The purpose of this study is to determine if this additional glycosylation affects the inhibitory ability of various COX‐2 inhibitors. COS‐1 cells were transiently transfected with either the wild‐type or Asn580‐mutant COX‐2 gene. Subsets of both cell groups were treated with various concentrations of either Aspirin, Flurbiprofen, Ibuprofen, or Celecoxib. After addition of the COX‐2 substrate arachidonic acid to inhibitor‐treated and untreated (control) cells, media was collected and subjected to an ELISA which measured levels of the downstream product prostaglandin E2. Results indicate that, at low concentrations, all of the inhibitors seem to have a greater effect on the 70/72 kDa glycoform. However, the effects of aspirin and flurbiprofen were less profound. This indicates that glycosylation of COX‐2 at Asn580 influences the efficacy of COX‐2 inhibitors.