Increased expression of the mRNA for hormone-sensitive lipase in adipose tissue of cancer patients.

The expression of genes coding for regulatory enzymes involved in the uptake, synthesis and mobilisation of lipid was measured in adipose tissue of cancer patients. Total RNA was isolated from subcutaneous adipose tissue of control and cancer patients and the various mRNAs measured by Northern blot analysis. The total lipoprotein lipase enzymic activity and the relative levels of the mRNAs for lipoprotein lipase and for fatty acid synthase were not significantly different between cancer patients and control patients. However, there was a significant two-fold increase in the relative level of mRNA for hormone-sensitive lipase (HSL) in adipose tissue of cancer patients compared with control patients. The cancer patients also exhibited a two-fold elevation in serum triacylglycerol levels and serum free fatty acid levels. There was a significant correlation between the serum free fatty acid level and expression of HSL mRNA in the adipose tissue. The serum levels of insulin and tumour necrosis factor-alpha were not different between cancer and control patients. The results suggest that at least one of the mechanisms for depletion of lipid from adipose tissue in cancer patients operates at the level of increased expression of mRNA of the lipolytic regulatory enzyme, hormone-sensitive lipase.