CTGF inhibits cell motility and COX-2 expression in oral cancer cells

Oral squamous cell carcinoma (SCC) has a striking tendency to migrate and metastasize. Cyclooxygenase (COX)-2, the inducible isoform of prostaglandin synthase, has been implicated in tumor metastasis. Connective tissue growth factor (CTGF), a secreted protein that binds to integrins, modulates the invasive behavior of certain human cancer cells. However, the effect of CTGF on migration activity and COX-2 expression in human oral cells is mostly unknown. Here we found that CTGF reduced the migration and expression of COX-2 in human oral cancer cells. αvβ5 monoclonal antibody (mAb), phosphatidylinositol 3-kinase inhibitor (PI3K; Ly294002 and wortmannin) and Akt inhibitor reversed the CTGF-inhibited the migration and COX-2 down-regulation of oral cancer cells. CTGF stimulation decreased the phosphorylation of focal adhesion kinase (FAK), PI3K and Akt. In addition, c-Jun siRNA also antagonized the CTGF-inhibited migration and COX-2 expression. Moreover, CTGF decreased the binding of c-Jun to the AP-1 element on the COX-2 promoter. Taken together, our results indicated that CTGF inhibits the migration of oral cancer cells by decreasing COX-2 expression through the αvβ5 integrin receptor, FAK, PI3K, Akt, c-Jun and AP-1 signal transduction pathways.