Matrix metalloprotease-9 expresssion in meningioma: Correlation with growth fraction and role of gender. A pilot immunohistochemical study

Objective Matrix metalloproteases (MMPs), particularly MMP2 and MMP9 increase tumor invasion and edema in meningiomas. Although lesser recognized, MMPs may also enhance cell growth via liberating growth factors or via cleaving inactive growth factors into active isoforms. However, there exist very few studies, which investigated correlation of MMPs with growth fraction in meningiomas. Meningiomas are seen more frequently in women and their growth accelarate during pregnancy. However, no study examined whether MMP-expressions in meningioma differ with gender. Patients and Methods In a pilot immunohistochemical study, we analyzed the correlation of MMP9 expression with Ki67 index and whether gender influences MMP9 expression. We retrospectively selected 24 meningioma cases including 10 cases with WHO Grade-1 tumors and 7 cases each with WHO Grade-2 and 3 tumors, respectively. Results We separately determined the intensity and area of MMP9 staining and also calculated an expression index by multiplying these two parameters. Spearman correlation analyses revealed that MMP9 staining intensity, staining area and expression index significantly correlated with Ki67 proliferation index. MMP9 staining indices were significantly higher in women specimens. Conclusion If these findings will be confirmed in larger series, MMP-inhibitors and female hormone receptor-antagonists may be combined to augment chemotherapy efficacy and to attenuate invasion in high-grade meningiomas.