Cyclooxygenase-2 (COX-2) expression by immunohistochemistry in glioblastoma multiforme

Cyclooxygenase-2 (COX-2) (an enzyme responsible for the conversion of arachidonic acid to prostaglandin) upregulation has been described in association with a variety of tumors including gliomas. This study reviews the immunohistochemical profile of 47 glioblastoma multiforme using COX-2 antibody and correlates the results with MIB-1 (marker of cell proliferation) immunostaining. Positive staining with COX-2 was observed in 35 tumors (74.5%); more than 10% tumor cell positivity was seen in 10 tumors (21.3%). Immunostaining results were as follows: no staining, N = 12 (25.5%); 0% to 5% of tumor cells, N = 20 (42.6%); 5% to 10%, N = 5 (10.6%); 10% to 20%, N = 4 (8.5%); 20% to 50%, N = 4 (8.5%); and greater than 50%, N = 2 (4.3%). The mean MIB-1 labeling index for all tumors ranged from 3.0 to 76.4 (mean, 19.6). Mean MIB-1 labeling indices were higher in tumors with greater than 5% COX-2 immunostaining (mean MIB-1 labeling index, 23.5) versus tumors with 0% to 5% COX-2 immunostaining (mean MIB-1 labeling index, 17.7). There is evidence of COX-2 expression by immunohistochemistry in the majority of glioblastoma multiforme. As a group, tumors with a higher rate of cell proliferation tended to have increased expression of COX-2. These findings are significant in that therapeutic agents, which inhibit COX-2, are currently available and may play a role in the management of glioblastoma multiforme.