Membrane phospholipid composition and membrane fluidity of human brain tumour: a spin label study.

Abstract

Membrane fluidity in membrane phospholipids of brain tumours was investigated and compared with those of white and grey matter. Fifteen brain tumours including 5 gliomas, 5 meningiomas and 5 metastatic cancers were examined. These samples were frozen immediately after extirpation in liquid nitrogen. After extraction of total lipids from the tumour tissues, membrane phospholipids were separated and analysed by thin-layer and gas-liquid chromatography. The fluidity of the phospholipid membrane was studied by electron spin resonance (ESR) spectroscopy, using a stearate spin probe. The fatty acid composition of total phospholipid of brain tumours was characterized by an increase in linoleic and arachidonic acids when compared to the control brain. The percentage of palmitoleic acid was higher in gliomas and metastatic tumours than in meningiomas. Furthermore, in the brain tumour tissues, the decreases of phosphatidylethanolamine and phosphatidylserine and the increase of phosphatidylcholine were observed when compared with grey or white matter with the exception of meningioma. There was some difference in phospholipid membrane fluidity between brain tumour and control brain tissue. The order parameter calculated from ESR spectra became higher in the following order: metastatic brain tumour, less than meningioma, less than grey matter, less than glioma, less than white matter. These results suggest that the phospholipid metabolism in the brain tumour is different from that of the normal brain, and this difference may affect the alteration of membrane physical properties which exhibit in part the character of the transformation.