Expression of prostaglandin H synthase-2 in human brain tumors

Numerous studies have demonstrated that prostaglandin H synthase-2 (PHS-2) is involved in gastrointestinal carcinogenesis, and that nonsteroidal anti- inflammatory drugs (NSAIDs), which inhibit PHS, can reduce the risk of colo n cancer. In brain tumors, elevated prostaglandin production and its correl ation to anaplastic grade of gliomas have been demonstrated. To determine w hether the increased prostaglandin production is due to enhanced expression of PHS-2 and whether the up-regulation of PHS-2 has any correlation to his topathological findings in brain tumors, we evaluated the profile of PHS ex pression in several human glioma cell lines and surgical specimens from pat ients with various types of brain tumors. In glioma cell lines, five out of six cell lines showed constitutive expression of PHS-2. whereas PHS-I was weakly expressed in all of them. All surgical specimens., except an ependym oma, which expressed both isozymes equally, expressed PHS-2 mRNA predominan tly. Immunohistochemistry of various types of brain tumors., including six glioblastomas, nine astrocytomas, six meningiomas, five medulloblastomas, f our craniopharyngiomas, three ependymomas, three neurinomas, two oligodendr ogliomas, two malignant lymphomas, two dysembryoplastic neuroepitherial tum ors and one metastatic brain tumor showed PHS-2 staining in most cases. In gliomas, astrocytomas (grade 2 and 3) were strongly stained, but the staini ng intensity of glioblastomas was relatively weak. Meningiomas and a metast atic brain tumor were also strongly stained. Our data thus suggest that mos t brain tumors express PHS-2, which may also play a role in tumorigenesis i n the brain.