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. Cancer 2003;97:2814–21. © 2003 American Cancer Society.
DOI 10.1002/cncr.11387