cyclic-gmp and Neurilemmoma

Since the effects of cyclic nucleotides are mediated via protein kinases activation, we have studied the properties and regulation of these enzymes in cytosol and particulate fraction of normal cerebral tissues and of some human brain tumors. We found that distribution and activity of cyclic nucleotide-dependent protein kinases are regulated differently among various brain tumors and in comparison to normal gray and white matter. Pathological tissues show an higher cGMP-dependent protein kinase and this biochemical pattern is particularly evident in tumors with more pronounced malignancy. These data further confirm the hypothesis of a correlation between the increase of cGMP function and cellular growth and malignancy.

Topics: Astrocytoma; Brain Neoplasms; Cyclic AMP; Cyclic GMP; Cytosol; Glioma; Humans; Kinetics; Neurilemmoma; Protein Kinases

Several reports have suggested that cylcic guanosine 3'-5' monophosphate (cGMP) and cyclic 3'-5' adenosine monophosphate (cAMP) are involved in the regulation of cellular proliferation. Following our previous reports on the cAMP system in human brain tumors, we decided to investigate the cGMP system in the same pathological tissues by studying the activity of guanylate cyclase and cGMP-phosphodiesterase (cGMP-PDE). We found that the activity of both enzymes is lower in neurinomas and glioblastomas than in meningiomas or in normal cerebral cortex. Furthermore, the subcellular distribution of guanylate cyclase in human cerebral cortex differs from that of neurinomas and glioblastomas. On the basis of such observations we have discussed the possibility that the regulatory mechanism of the enzymes related to the cyclic nucleotide metabolism is altered in brain tumors.

Topics: Brain Neoplasms; Cerebral Cortex; Cyclic GMP; Glioma; Guanosine; Guanylate Cyclase; Humans; Meningioma; Neurilemmoma; Phosphoric Diester Hydrolases