期刊名称:Proceedings of the National Academy of Sciences
印刷版ISSN:0027-8424
电子版ISSN:1091-6490
出版年度:1993
卷号:90
期号:5
页码:2065-2068
DOI:10.1073/pnas.90.5.2065
语种:English
出版社:The National Academy of Sciences of the United States of America
摘要:Glutathione transferase P (GST-P; glutathione transferase, EC 2.5.1.18 ) is known to be specifically expressed at high levels in precancerous lesions and in hepatocellular carcinomas from a very early phase of chemically induced hepatocarcinogenesis in the rat. The almost invariable occurrence of this phenotype in these lesions strongly suggests a mechanism by which GST-P gene is activated together with a crucial transforming gene of liver cells. To distinguish the two alternative possibilities--either the GST-P gene is coactivated with a closely located transforming gene by a cis mechanism or it is activated in trans by a common trans-acting factor--we carried out carcinogenesis experiments using transgenic rats harboring the bacterial chloramphenicol acetyltransferase reporter gene ligated to the upstream regulatory sequence of the GST-P gene. In each of three independent lines tested, liver foci and nodules produced by chemical carcinogens (Solt-Farber procedure) were found to express high levels of chloramphenicol acetyltransferase activity, indicating clearly that the GST-P gene is activated by a trans mechanism during hepatocarcinogenesis.