A great deal of experimental evidence shows that the growth of
tumors is accompanied by significant changes at the expense of the cell surface. For the present paper, we set out to analyse the composition of
membrane lipids (
cholesterol,
phospholipids, neutral and
acidic glycosphingolipids, sulphatides) in human
cerebral astrocytomas, which is a group of
tumors that offer a valid model for the study of the various grades of cellular transformations in vivo. The results obtained in the present study permit us to draw a series of conclusions in relation to the
malignancy grade of glial human
tumors. In particular, an increase in the
malignancy is accompanied by: 1) a reduction of the total
lipids, a reduction that involves all the principal classes of
lipids of the plasma membrane, for which it has been possible to demonstrate a correlation of an exponential nature, which is significant with the increasing of the histological grading; 2) a gradual accumulation, in the area of
glycosphingolipids, of lattosylceramide and GD3, molecules that can constitute a valid marker of the
malignancy grade; moreover, the
glycolipid composition of
astrocytomas of high degree differs from that of
tumors of a low grade because of the presence of more complex
glycolipids (trihexosylceramide and tetraosylceramide); 3) a gradual increase, in the area of
phospholipids, of PC/PE and PC/SM ratios, indices of the microviscosity of the membrane. The data obtained suggest that the profound modifications of
membrane lipids, which are gradually accompanied by a progressive increase in the
malignancy of the
tumor, can, on the one hand, be responsible for functional variations connected with neoplastic growth, and, on the other hand, constitute valuable biochemical parameters which are useful, together with histological studies, in the diagnosis of these
tumors.