Inhibition of COX‐2 with NS‐398 decreases colon cancer cell motility through blocking epidermal growth factor receptor transactivation: possibilities for combination therapy

The use of non-steroidal anti-inflammatory drugs has proved of great interest in the prevention and treatment of colorectal cancer, although their precise mechanisms of action remain unclear. Overexpression of cyclooxygenase-2 (COX-2) and subsequent prostaglandin production promote metastasis and have been shown to increase cell motility in vitro . Objective : We have aimed to elucidate whether specific inhibition of COX-2 with NS-398( NS-398is a selective inhibitor of COX-2) would be able to inhibit motility of colorectal cancercells and whether this was modulated through epidermal growth factor receptor (EGFR) transactivation. Materials and Methods :A transwell filter assay was used to study cell motility. Expression of COX-2, EGFR phosphorylation and prostaglandin E 2 (PGE 2 ) receptors were assessed by Western blot analysis and reverse transcriptase-polymerase chain reaction. PGE 2 concentrations after NS-398treatment were estimated by enzyme immunoassay. Results : Treatment with NS-398significantly reduced PGE 2 levels and reduced cell migration in the HT29 and HCA7 colorectal carcinoma cell lines and this effect was rescued by addition of PGE 2 . Furthermore, specific inhibition of COX-2 with NS-398reduced EGFR phosphorylation in colorectal cancercells. Direct inhibition of EGFR activity with AG1478 reduced PGE 2 -stimulated motility, clearly demonstrating that PGE 2 acts via the EGFR-signalling pathway. The novel combination of NS-398and AG1478 dramati- cally reduced migration of colorectal cancercells. Conclusion : The data presented indicate that the use of NS-398in chemoprevention and adjuvant therapy for colorectal cancermay work in part, through the inhibition of cell motility. Furthermore, our data