Matrix Metalloproteinases and Tissue Inhibitors of Metalloproteinases in Pituitary Adenomas: Possible Markers of Neuroendocrine Cells

Matrix metalloproteinases (MMPs) are involved in remodeling processes and have been immunocytochemically localized in some endocrine glands and their tumors. Using anterior pituitary gland and pituitary adenomas, immunocytochemical localization of MMP-2 (gelatinase-A),-9 (gelatinase-B), tissue inhibitor of metalloproteinase (TIMP)-1 and-2 was performed. Normal anterior-pituitary cells all contain MMPs and lesser amount of TIMPs, whereas far fewer MMPs and TIMPs are identified in anterior pituitary adenomas. There is no correlation between pituitary hormone and MMPs-TIMPs localization, thus MMP-TIMP homeostasis may not be involved in hormone synthesis and secretion of anterior pituitary cells and their adenomas. Because MMPs and TIMPs are more abundantly and specifically localized in pituitary cells and their adenomas, MMPs and TIMPs may be included as markers for endocrine cells, including anterior-pituitary cells.