Up-regulation of I-2(PP2A)/SET gene expression in rat primary hepatomas and regenerating livers

I-2(PP2A)/SET, an inhibitor of protein phosphatase 2A, is supposed to be on e of the oncoproteins associated with human myeloid leukemia. The I-2(PP2A) /SET gene expression was observed ubiquitously among all the rat tissues ex amined, but low in liver. Of interest is that the expression in the rat pri mary hepatomas and hyperplastic nodules was significantly elevated. The exp eriments using regenerating livers after partial hepatectomy showed that th e expression of I-2(PP2A)/SET mRNA was low at the quiescent hepatocytes, bu t up-regulated at 12-24 h after partial hepatectomy, which corresponds to t he mid G1 to S transition in the cell cycle. These results suggested the im portance of I-2(PP2A)/SET in the hepatocarcinogenesis and hepatic cell prol iferation. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.