Peroxisome proliferator-activated receptor alpha (PPARalpha) regulates lipid metabolism in the liver. It is unclear, however, how this receptor changes in liver cancer tissue. On the other hand, mouse carcinogenicity studies showed that PPARalpha is necessary for the development of liver cancer induced by peroxisome proliferators, and the relationship between PPARalpha and the development of liver cancer have been the focus of considerable attention. There have been no reports, however, demonstrating that PPARalphais involved in the development of human liver cancer.

The subjects were 10 patients who underwent hepatectomy for hepatocellular carcinoma. We assessed the expression of PPARalpha mRNA in human hepatocellular carcinoma tissue and non-cancerous tissue, as well as the expression of target genes of PPARalpha, carnitine palmitoyltransferase 1A and cyclin D1 mRNAs. We also evaluated glyceraldehyde 3-phosphate dehydrogenase, a key enzyme in the glycolytic system.

The amounts of PPARalpha, carnitine palmitoyltransferase 1A and glyceraldehyde 3-phosphate dehydrogenase mRNA in cancerous sections were significantly increased compared to those in non-cancerous sections. The level of cyclin D1 mRNA tends to be higher in cancerous than non-cancerous sections. There was a significant correlation between the levels of PPARalpha mRNA and cyclin D1 mRNA in both sections.

The present investigation indicated increased expression of PPARalpha mRNA and mRNAs for PPARalpha target genes in human hepatocellular carcinoma. These results might be associated with its carcinogenesis and characteristic features of energy production.

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