Metallothionein in Gliomas

Metallothionein (MT) is a low molecular weight, intracytoplasmic protein that has a high affinity for heavy metals. MT plays a role in the storage and metabolism of essential trace elements and in detoxification of toxic heavy metals in normal tissues. In systemic malignant tumors, MT is thought to be related to the cellular mechanism of drug resistance to anticancer agents, especially platinum compounds. We studied the expression of MT in 20 gliomas and 3 autopsied brains using immunohistochemical and reverse transcriptase-polymerase chain reaction (RT-PCR) methods. In autopsied brains, MT expression was seen in astrocytes in the cerebral gray matter and white matter and in the cerebellum. Neurons, ependyma, and oligodendrocytes did not show MT immunoreactivity. In gliomas, MT staining was seen in both nucleus and cytoplasm of tumor cells. Expression of MT was most prominent in glioblastomas and less intensive in low-grade gliomas. We concluded that intensity of MT expression may correlate with histological grading of gliomas.