Chemical hepatocarcinogenesis in transgenic mice overexpressing mature TGFbeta-1 in liver

The role of transforming growth factor beta I (TGF-beta 1) in carcinogenesi s is a controversial issue. Certain results suggest a promoter role of this growth factor whilst in other experimental models TGF-beta 1 seems to inhi bit the process of tumorigenesis. In an attempt to resolve this problem, we have performed chemical hepatocarcinogenesis experiments on transgenic mic e expressing a high level of active TGF-beta 1 in their liver. Transgenic p roduction of TGF-beta 1 did not result in spontaneous tumour formation duri ng our observation period. However, two carcinogens, thioacetamide and N-OH acetylaminofluorene, were more potent in transgenic than in wild-type mice , whereas aflatoxin B1 was equally effective in both groups. Our observatio ns suggest that an increased level of TGF-beta 1 in the liver does not prov ide protection against the effect of chemical carcinogens. (C) 1999 Elsevie r Science Ltd. All rights reserved.