Lysosomal enzymes in cerebrospinal fluid as a marker of brain tumor

Abstract

Lysosomal enzymes, β-glucuronidase, acid phosphatase, and β-N-acetylglucosaminidase, in the cerebrospinal fluid of the patients with brain tumor were assayed by fluorospectrophotometric techniques. Three hundred and three CSF samples were obtained from 128 patients suffering from various kinds of neurological diseases and the activity of the three lysosomal enzymes was assayed. Student's t-test was used for statistical analysis. In the cases of glioblastoma, medulloblastoma, malignant lymphoma, and pineal tumor, enzyme activity was found significantly elevated, and, was further enhanced when the tumor showed subarachnoid dissemination. Irradiation to the neural axis or intrathecal administration of chemotherapeutic agent elevated the enzyme activity. The activity then showed gradual attenuation while the therapeutic effect was sufficient for decreasing the size of the tumor mass. By contrast, the activity remained unchanged or increased, if the treatment was not effective and the tumor kept growing. In cases of subarachnoid dissemination or metastases the activity of the lysosomal enzymes became elevated before clinical manifestation. It was also elevated with clinical recurrence of the resected tumors. In vitro experiments were performed using a monolayer culture of rat C6 glioma cells. Enzyme activity of the culture medium with irradiation or with chemotherapeutic agent was examined. The activity was elevated as the cell growth reached the plateau phase, became maximum when the monolayer culture showed degeneration and desquamation, and then markedly decreased as the culture cells reduced in number. The activity was found to correlate well with the number of cultured cells in each experimental condition. It was considered that the lysosomal enzyme activity indicated cell damage from the therapeutic effect and the attenuation of the activity was due to subsequent cell loss. In conclusion, lysosomal enzyme activity can be a good biochemical marker of brain tumor, especially in clinical observation of tumor recurrence or dissemination.