EXPRESSION OF PROSTAGLANDIN G H SYNTHASE TYPE-1, BUT NOT TYPE-2, IN HUMAN OVARIAN ADENOCARCINOMAS/

Prostaglandin endoperoxide synthase (PGHS) is a key rate-limiting-enzy me in prostaglandin biosynthesis. PGHS has recently been shown to be e xpressed in human colorectal cancers and in experimental cutaneous pap illomas and carcinomas. However, PGHS expression has not been investig ated in ovarian cancers. The objectives of this study were to determin e whether PGHS isoenzymes are expressed in human ovarian cancer and, i f so, to identify which isoform is involved (PGHS-1 and/or PGHS-2) and to characterize its cellular localization. Sixteen human ovarian aden ocarcinomas were studied by immunohistochemistry using specific antibo dies recognizing PGHS-1 or PGHS-2. Results showed that all adenocarcin omas demonstrated the presence of tumor cells expressing PGHS-1 but no t PGHS-2. Patterns of staining of tumor cells varied among different t ypes of adenocarcinomas, with cells presenting either a mostly diffuse cytoplasmic immunoreactivity or, alternatively, a staining mainly con centrated around the nucleus. No correlation between the intensity of the immunostaining and the degree of malignancy of tumors could be est ablished (r = -0.03; p>0.05). Immunoblot analysis with PGHS-1-selectiv e antibodies of cell extracts from adenocarcinomas revealed the presen ce of a characteristic 72,000 M-r immunoreactive band. Therefore, thes e results show for the first time that PGHS-1 is expressed in human ov arian adenocarcinomas.