title: Cyclooxygenase-2 expression in human pituitary tumors.
abstract: BACKGROUND
  Cyclooxygenase-2 (COX-2) plays a role in progression of colon, breast, pancreas, and lung carcinomas. The authors investigated COX-2 expression in pituitary tumors.
  
  
  METHODS
  Expression of COX-2 was evaluated in 164 surgically removed human pituitary tumors. Correlation of COX-2 with MIB-1, a cell proliferation marker, as well as angiogenesis, patient age, gender, tumor type, size, invasiveness, and metastatic potential was investigated.
  
  
  RESULTS
  Cyclooxygenase-2 immunoreactivity was confined to the cytoplasm of tumor cells, whereas the nuclei were unlabeled. Few normal peritumoral adenohypophysial cells showed slight COX-2 cytoplasmic immunoreactivity. The staining intensity and the percentage of immunopositive cells were higher in tumors. Most pituitary tumors (96%) were COX-2-immunopositive. Expression was strong in 60 (44%), moderate in 39 (28%), and weak in 32 (24%). Male gonadotroph adenomas and null cell adenomas showed a high level of COX-2 expression. Growth hormone-producing adenomas, prolactin-producing adenomas, thyrotropic hormone-producing adenomas, female gonadotroph adenomas, silent adrenocorticotropic hormone-producing adenomas, and silent subtype 3 adenomas had a low level of COX-2 expression. Significant correlation was demonstrated with patient age, but not with tumor size, invasiveness, and MIB-1 labeling indices. Expression was medium to high in 76% of macroadenomas and in only 45% of microadenomas. Strong correlations were noted with angiogenesis markers, such as microvessel density and surface density.
  
  
  CONCLUSIONS
  Correlation with angiogenesis suggests that COX-2 may be involved in the regulation of angiogenesis in pituitary tumors. Phamacologic inhibition of COX-2 activity might suppress angiogenesis in pituitary tumors and may provide a novel approach for medical therapy.
authors.affiliation: Department of Laboratory Medicine and Pathobiology, St. Michaels Hospital, University of Toronto, Ontario, Canada.
authors.forename: Sergio
authors.initials: S
authors.lastname: Vidal
authors.forename: Kalman
authors.initials: K
authors.lastname: Kovacs
authors.forename: David
authors.initials: D
authors.lastname: Bell
authors.forename: Eva
authors.initials: E
authors.lastname: Horvath
authors.forename: Bernd W
authors.initials: BW
authors.lastname: Scheithauer
authors.forename: Ricardo V
authors.initials: RV
authors.lastname: Lloyd
mesh_terms: D000236:Adenoma; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D051546:Cyclooxygenase 2; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000032:analysis*; D019394:Ki-67 Antigen / Q000032:analysis; D008297:Male; D008565:Membrane Proteins; D008875:Middle Aged; D010911:Pituitary Neoplasms / Q000201:enzymology*; D011451:Prostaglandin-Endoperoxide Synthases / Q000032:analysis*
chemical_list: D007527:Isoenzymes; D019394:Ki-67 Antigen; D008565:Membrane Proteins; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases