title: Constitutive expression of mature transforming growth factor beta1 in the liver accelerates hepatocarcinogenesis in transgenic mice.
abstract: Transforming growth factor beta-1 (TGF-beta1) is a potent inhibitor of hepatocyte growth both in vivo and in vitro. In this study, we analyzed the effects of TGF-beta1 on both naturally occurring and diethylnitrosamine-induced hepatocarcinogenesis using single transgenic TGF-beta1 and double transgenic c-myc/TGF-beta1 mice in which the expression of both transgenes was targeted to the liver. Hepatocellular tumors developed spontaneously in 59% (10 of 17) of the TGF-beta1 mice by 16-18 months of age. Coexpression of TGF-beta1 and c-myc transgenes in the liver accelerated hepatic tumor growth in both the presence and absence of carcinogenic treatment. Moreover, diethylnitrosamine-initiated tumors in the c-myc/TGF-beta1 mice showed a high rate of malignant conversion associated with a reduced expression or lack of TGF-beta receptor type II. The results suggest that overexpression of TGF-beta1 may contribute to liver carcinogenesis and that loss of TGF-beta receptor type II transduced inhibitory growth signals and up-regulation of c-myc are critical steps in liver tumor progression.
authors.affiliation: Laboratory of Experimental Carcinogenesis, Division of Basic Sciences, National Cancer Institute, Bethesda, Maryland 20892, USA.
authors.forename: V M
authors.initials: VM
authors.lastname: Factor
authors.forename: C Y
authors.initials: CY
authors.lastname: Kao
authors.forename: E
authors.initials: E
authors.lastname: Santoni-Rugiu
authors.forename: J T
authors.initials: JT
authors.lastname: Woitach
authors.forename: M R
authors.initials: MR
authors.lastname: Jensen
authors.forename: S S
authors.initials: SS
authors.lastname: Thorgeirsson
mesh_terms: D000818:Animals; D015152:Blotting, Northern; D004052:Diethylnitrosamine; D015972:Gene Expression Regulation, Neoplastic; D016259:Genes, myc; D007150:Immunohistochemistry; D008114:Liver Neoplasms, Experimental / Q000139:chemically induced / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D018125:Receptors, Transforming Growth Factor beta / Q000378:metabolism; D015398:Signal Transduction; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D012333:RNA, Messenger; D018125:Receptors, Transforming Growth Factor beta; D016212:Transforming Growth Factor beta; D004052:Diethylnitrosamine