Matrix metalloproteinases and their inhibitors in human pituitary tumors

OBJECTIVE: To determine the expression of matrix metalloproteinases (MMP)-1 , -2, and -3 and the tissue inhibitors of metalloproteinases (TIMP)-1, -2, and -3 in 12 tissue samples from normal pituitary glands and in 28 human pi tuitary tumors ranging from Grade 0 to Grade IV, and to establish a correla tion between the level of expression of MMPs and TIMPs and the tumor grade. METHODS: The expression of MMPs and TIMPs was determined by Western blottin g. MMP activity was detected by gelatin zymography. RESULTS: MMPs were expressed in the majority of tumors, and their levels of expression were unrelated to tumor grade or to their invasive phenotype. S ome correlation was observed between MMP activity detected by zymography an d tumor grade. TIMP-2 and TIMP-3 were poorly expressed in high-grade tumors and strongly expressed in normal pituitary glands and in the majority of l ow-grade tumors. CONCLUSION: No correlation could be established between the invasive potent ial of tumors and MMP-1, -2, and -3 expression levels. Some correlation was observed between MMP activity detected by zymography and tumor grade. A go od inverse correlation was observed between TIMP-2 and TIMP-3 expression le vels and tumor grade. These data suggest that monitoring the expression of TIMP-2 and TIMP-3 or gelatinolytic activity could be of prognostic value.