Degrees of malignancy in human primary central nervous system tumors: ornithine decarboxylase levels as better indicators than adenosylmethionine decarboxylase levels.

The levels of activity to ornithine decarboxylase (ODC) and adenosylmethionine decarboxylase (AMD) were measured in various types of primary human tumors of the central nervous system (CNS) and whenever possible were related to the malignancy of the tumor graded according to histopathologic criteria. In astrocytomas ODC levels increased linearly and progressively from infratentorial pilocytic astrocytoma (grade I) to glioblastoma multiforme (grade IV) and corrected well with the degree of histologic malignancy of the tumor. AMD activity levels, however, correlated with tumor malignancy only up to grade III astrocytoma. Medulloblastomas exhibited an unusual dichotomy with regard to the levels of polyamine biosynthetic decarboxylases (PBD): Medulloblastomas had the highest ODC activities of all the CNS tumors tested but had low AMD activities. In tumors of neuroepithelial tissue ODC level increases and, when present, AMD level increases were not due to proliferation of new blood vessels, because CNS hemangioblastomas had very low levels of both PBD activities. No significant differences in either of the PBD levels were observed among the several variants of meningiomas tested, the meningotheliomatous, the transitional, and the fibrous meningiomas. However, atypical forms of meningioma, i.e., those with mitotic figures, whatever the histologic variants, had higher levels of ODC, but not of AMD, than the typical forms, i.e., those without mitotic figures.