METALLOTHIONEIN OVEREXPRESSION IN HUMAN BRAIN-TUMORS

Metallothioneins (MTs) are metal binding proteins overexpressed in var ious human neoplasms which are associated with resistance to cytotoxic drugs. A series of 156 archival human brain tumours were investigated immunohistochemically for expression of MTs; these included 10 low-gr ade gliomas, 44 high-grade gliomas, 98 meningeal rumours (19 classical , 30 atypical, 38 anaplastic meningiomas, and 11 haemangiopericytomas or papillary meningiomas), and 4 other rumours. Low-grade gliomas show ed heterogeneous MT expression; 32 high-grade gliomas (72.7%) showed M T expression of more than 25% of tumour cells without statistically si gnificant differences between first operations and recurrent tumours. In 2 glioblastomas, the presence of MT was confirmed by Western blotti ng. The extent of MT immunoexpression showed a statistically significa nt inverse relationship to the degree of p53 immunoreactivity. In meni ngiomas, a tendency to a higher percentage of MT-expressing cells was observed from classical over atypical to anaplastic meningiomas, but t hese differences were not statistically significant. In conclusion, MT expression is present in a significant portion of, especially maligna nt, brain rumours and might be involved in their poor response to anti neoplastic drugs.