We examined nm23-H1 protein levels in human oligodendrogliomas by immunohistochemistry. This class of brain tumor does not form spontaneous metastases, but its progression from benign (oligodendroglioma) toward malignant phenotype (oligodendroglioma transitionale and glioblastoma oligodendrogliale) can be followed. Two types of tumors, ODG-II and ODG-T, were highly positive for nm23 protein. However, there was no clear correlation between the extent of protein expression and tumor aggressiveness. No nm23 protein was detected in nonproliferative normal brain tissues and was found in only a few ODG-I specimens. As cell proliferation becomes more pronounced (OGD-II, ODG-T), nm23 protein becomes detectable in almost all samples. However, of the glioblastoma oligodendrogliale samples examined, 76% were negative for nm23-H1 protein. suggesting a change in nm23-H1 gene expression with increasing neoplastic progression. Our findings are in contrast to a proposed role of nm23-H1 protein as a tumor metastasis suppressor and support that it cannot serve as a reliable prognostic tumor indicator in all cases. However, our findings may contribute to a better understanding of glial tumor development and improve the accuracy of tumor diagnosis.

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