Neutral lipids production, transport, utilization

Malignant tumors increase the levels of triacylglycerol carriers, i.e., very low density lipoproteins (VLDL), and lower the concentrations of cholesterol carriers, i.e., low-density and high-density lipoprotein fractions (LDL and HDL). The rise in VLDL levels may be caused by increased hepatic secretion of this lipoprotein fraction and reduced conversion of VLDL to LDL caused by cachexia-inducing proteins. The hypocholesterolemia is probably related to lowered LDL and HDL cholesterol levels that depend on a greater utilization of cholesterol for the biogenesis of new membranes and the accumulation of cholesteryl ester in tumoral tissue. The involvement of neutral lipids in cancer development is further evidence by the occurrence of certain tumors following the intake of high-fat diets. Furthermore, epidemiological and experimental studies showed that hypercaloric diets rich in n-6 polyunsaturated fatty acids (n-6, PUFA) stimulated tumorigenesis, while diets rich in marine fats (n-3, PUFA) inhibited it. In conclusion, changes ill neutral lipids production, transport and utilization play an importantly role in determining the alterations in energy storage and membrane properties observed in tumor cells.