Expression of matrix metalloproteinase-9 in human glioma and meningioma

Aim of the Study Matrix Metalloproteinase-9 (MMP-9), a peptidase actively implicated in the degradation of the extracellular matrix, is often linked to the malignant phenotype of tumor cells and plays a critical role in tumor cell invasion, metastasis, angiogenesis. In this preliminary observational study, we correlate expression of serum MMP-9 with the expression of the same protein in the tumor tissue -the putative source of the biomarker- of patients with intracranial neoplasms. Methods By zymography we determined MMP-9 in sera from 48 patients with intracranial tumors. Of these patients 20 had glioma (3 grade I, 2 grade II, 4 grade III and 11 grade IV) and 28 had meningioma (16 grade I, and 12 grade II). The sera of 25 healthy volunteers with no concomitant illnesses were used for controls. In surgical resected specimens immunohistochemical evaluation of MMP-9 was performed. Results Sera MMP-9 lytic activities were significantly higher in tumor specimens compared to healthy controls (p<0.001). As it concerns tissue expression we observed that MMP-9 was absent (both in vessels and cells) in glioma grade I, absent in vessels but present in cells (cytoplasm and nucleus) in grade II, absent in vessels and present in cytoplasm in grade III, and strong reactive in vessels and weakly in grade IV. Conclusions These data suggest that MMP-9 has an important role in remodeling associated with neovascularization. Vice versa, in meningioma specimens, MMP-9 reactivity is in cytoplasm and significantly enhanced in atypical meningioma compared with grade I specimens (p=0.036). Therefore MMP-9 may be an important mediator of brain-invasive growth. Our results suggest that serum and tissue MMP-9 might provide clinicians additional objective information on intracranial carcinomas. Nevertheless, due to the small number of patients, the conclusion may not be transferable to the general population and therefore merits further evaluation.