POLYAMINE METABOLISM IN GLIOMAS

Biosynthesis of the polyamines putrescine, spermidine, and spermine ha s been found to be activated in tissues with cellular proliferation. I n the present study we have investigated polyamine levels and the acti vity of the first rate-limiting enzyme ornithine decarboxylase (ODC) i n tumour samples obtained during operation of 202 patients with glioma s. Biochemical data were closely related to the grading of malignancy and to the morphological characteristics of each sample. Mean ODC acti vity was significantly higher in all gliomas as compared to peritumour al non-neoplastic brain. Furthermore, it was significantly higher (p l ess than or equal to 0.001) in anaplastic gliomas who grade III and IV (9.0 +/- 9.6 nmol/g/h) than in gliomas WHO grade I and II (3.3 +/- 4. 2 nmol/g/h). Highest enzyme activity (58.5 nmol/g/h) was found in soli d and vital parts of malignant tumours, whereas predominantly necrotic areas exhibited low ODC activity (< 1 nmol/g/h). Thus, intra- and int erindividual variability of ODC activity corresponded well to histomor phological heterogeneity in high-grade gliomas. Putrescine levels also increased with rising grade of malignancy, whereas spermidine and spe rmine levels did not correlate with the histological grading. In concl usion, high ODC activity represents a biochemical marker of malignancy in gliomas, but low values do not prove benignity. The present study reinforces the need of further and more extensive tumour sampling clos ely related to follow-up investigations in the heterogeneous group of gliomas.