Matrix metalloproteinase-2 and matrix metalloproteinase-9 expression in canine and feline meningioma.

Fifty-one meningiomas obtained from 28 dogs and 23 cats were selected for this study to investigate the immunohistochemical expression of matrix metalloproteinase (MMP)-2 and MMP-9 and to compare it to the reverse transcriptase subunit of human-telomerase, progesterone receptor expression, and the proliferative index of the tumors, expressed by Ki67 and proliferating cellular nuclear antigen. Paraffin-embedded tumor tissue was obtained from biopsy samples (28 cases) and at necropsy (23 cases). The most common histotype was malignant in dogs (12/28) and transitional in cats (12/23). Slides immunolabelled for MMPs showed a diffuse cytoplasmic pattern. Twenty-one cases (19 dogs and 2 cats) did not express MMP-2, while only 2 cases were completely negative for MMP-9. The highest values of MMP-2 and MMP-9 were observed in a psammomatous and meningothelial tumor, respectively. On statistical analysis, MMP-2 expression did not show a significant correlation with MMP-9. Moreover, both MMP expressions failed to show significant variance among histologic patterns of the tumor and correlation with the proliferative index. MMP immunolabeling showed an inconstant correlation with progesterone receptor expression. No significant correlation was found between MMP and reverse transcriptase subunit of human-telomerase expression. In feline meningiomas, the MMP-2 value was significantly higher than in canine tumors and the MMP-9 value tended to be low for meningiomas with a follow-up duration from the 23(rd) month to the 44(th) month. In cats, the longer the time from surgery, the lower the proliferative index seemed to be. In dogs, we failed to find a correlation between MMP expression and the follow-up duration.