TRANSFORMED BUT NOT NORMAL HEPATOCYTES EXPRESS UCP2

Uncoupling protein 2 (UCP2) expression in liver is restricted to non-p arenchymal cells. By means of differential display screening between n ormal rat liver and H4IIE hepatoma cells we have isolated a cDNA clone encompassing part of UCP2 cDNA. Northern blot analysis revealed that UCP2 is expressed in some hepatocarcinoma cell lines, while it is abse nt in adult hepatocytes. UCP2, mRNA in H4IIE cells was downregulated w hen cells were cultured for 36 h in 0.1% serum and its expression was restored upon addition of 10% serum or phorbol esters. Hypomethylation of UCP2 was observed in transformed UCP2 expressing cells. Our result s indicate that UCP2 is expressed in some hepatocarcinoma cell lines a nd that serum components may participate in maintaining elevated UCP2 levels. (C) 1998 Federation of European Biochemical Societies.