Expression of matrix metalloproteinases in a series of 12 meningiomas

The expression of metalloproteinases was evaluated in a series of 12 mening iomas of various histological sub-types including 3 meningotheliomatous, 3 fibroblastic, 4 transitional and one psammomatous meningioma (WHO grade I) as well as one anaplastic meningioma (WHO grade III). No gelatinolytic acti vity could be detected in all tumor samples pointing towards no or very low activity of both MMP-2 and MMP-9. At least MMP-2 mRNA could be found in 10 out of 12 tumor samples by the reverse transcription PCR method (RT-PCR) f ollowed by electrophoresis on silver-stained polyacrylamide gels, which all ows the detection even of small traces of a specific mRNA. The PCR products were identified as MMP-2 sequences without introns (mRNA-derived) by direc t sequencing, thereby demonstrating a low transcriptional activity of the g ene. The translation of these mRNAs, however, did not result in amounts of protein detectable by immunohistochemistry or Western blotting. Therefore, neither MMP-2 nor MMP-9 should play a major role for tumor growth within du ra mater or bone structures or for brain infiltration in our tumor series. Therefore, other mechanisms must be responsible for extracellular matrix de gradation at least in a fraction of meningiomas.