Does a passive transport between modified plasma lipoproteins and cell membranes exist in cancer disease?

Malignant diseases increase the level of total lipids in blood and modify their distribution in lipoprotein carriers affecting lipid exchanges between serum and tissues. These exchanges take place by active and/or passive ways which coexist in most tissues. This work concerns the exploration of passive diffusion, using the red blood cell mechanism as a model. Lipid components of normal and cancerous rat erythrocytes have been investigated by Proton and Carbon high resolution Magnetic Resonance Spectroscopy (H-1 and C-13 MRS). As previously established, MRS yields the usual molar ratio cholesterol/phospholipids and moreover provides information on the length and degree of unsaturation of the phospholipid fatty acyl chains. No modification has been recorded in erythrocyte lipids between cancer and control populations. These data would suggest that erythrocytes can maintain membrane lipid homeostastis during malignancy. The numerous abnormalities noted in their membrane fuction remain to be explained.