Inhibition of cyclooxygenase-2 suppresses invasiveness of oral squamous cell carcinoma cell lines via down-regulation of matrix metalloproteinase-2 and CD44.

Expression of cyclooxygenase-2 (COX-2) in tumors is known to be associated with enhanced angiogenesis, suppression of host immunity, and tumor invasion. In the present study, human oral squamous cell carcinoma (OSCC) cell lines NA and HSC-4 were used to evaluate the effects of NS-398, a selective inhibitor of COX-2, and COX-2 antisense oligonucleotide (COX-2 AS) on the invasion activity of OSCC cells. Matrigel invasion assay revealed that the invasiveness of NA and HSC-4 was suppressed by treatment with either NS-398 or COX-2 AS. These reagents down-regulated the secretion of matrix metalloproteinase-2 (MMP-2) to culture supernatant as well as the expression of MMP-2 mRNA and protein. Membrane-type 1 matrix metalloproteinase (MT1-MMP), an activator of proMMP-2, was also down-regulated by treatment with these reagents. Furthermore, expression of CD44 on the surface of these cells was reduced by treatment with either NS-398 or COX-2 AS. In addition, MMP-2 antisense oligonucleotides reduced the expression of CD44 on the surface of both OSCC cell lines. These findings suggest that NS-398 and COX-2 AS suppress the invasiveness of OSCC cells via down-regulation of MMP-2 and CD44. Genetic or pharmacological inhibition of COX-2 may therefore be a beneficial strategy in the treatment of OSCC patients.