Effect of Glycosylation of Cyclooxygenase-2 (COX-2) on Dimerization and the Migratory Potential of Cells

Cyclooxygenase-2 (COX-2) is an enzyme in the prostaglandin synthesis pathway that catalyzes the conversion of arachidonic acid into prostaglandin G2 and prostaglandin G2 into prostaglandin H2. COX-2 is involved in various normal physiological functions; however its overexpression has been shown to play a role in cancer progression. COX-2 has two glycoforms weighing 72 and 74 kDa, the latter due to the glycosylation of Asn580 ~50% of the time. The purpose of this study was two-fold: (1) to determine whether glycosylation of COX-2 at Asn580 affected the enzyme’s ability to dimerize with itself; and (2) to elucidate the possible downstream phenotypic effects of this glycosylation, specifically on the metastatic potential of cells. The molecular dynamics program NAMD was used to simulate the COX-2 dimer. To test the effect of glycosylation on the migratory potential of cells, the wild-type or Asn580-mutant COX-2 gene was transfected into COS-1 cells that were then plated onto Boyden chambers and incubated 10-12 hours. Computer simulations of the COX-2 dimer have been constructed, and data are currently being collected to determine how glycosylation affects this interaction. The migration assay results show that COS-1 cells expressing the mutant COX-2 gene had 1.5-fold greater migratory ability than cells expressing the wild-type gene. This suggests that the lack of glycosylation of COX-2 at Asn580 enhances the migratory potential of cells and thus may contribute to metastasis