Adenylate cyclase activity and cyclic AMP content in human central nervous system tumors and in cerebrospinal fluid of patients bearing brain tumors

Abstract

Cyclic AMP (cAMP) is believed to be involved in differentiation and growth of cultured human and experimental brain tumors, showing an inverse relationship between cAMP levels and the role of malignant cell growth. cAMP concentration in cerebrospinal fluid (CSF) may also represent a useful approach for investigating changes in the regulation of central nervous system (CNS) metabolism and function. This study investigates cAMP system both in tumoral tissues and in CSF of patients affected by tumors of the central nervous system. The results show that the activity of the enzyme and cAMP content are significantly reduced in malignant tumors (26.92 ± 2.82 p mol cAMP/min/mg prot.) when compared to benign tumors (33.33 p mol cAMP/min/mg prot.) and normal brain tissue (56.19 p mol cAMP/min/mg prot.). A similar degree of reduction is present in malignant glial tumors, particularly in glioblastomas and metastatic carcinomas. cAMP concentrations in lumbar CSF is higher in controls (8.60 ± 0.68 p mol cAMP/ml) than in patients bearing benign tumors (4.70 ± 0.74p mol cAMP/ml) or malignant tumors (2.65 ± 0.57p mol cAMP/ml).