Carcinogenesis Advance Access originally published online on November 4, 2007
Carcinogenesis 2008 29(1):211-218; doi:10.1093/carcin/bgm236
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Autonomous growth and hepatocarcinogenesis in transgenic mice expressing the p53 family inhibitor DNp73
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1 Department of Vectorology and Experimental Gene Therapy, Biomedical Research Center, University of Rostock Medical School, Schillingallee 69, Rostock D-18055, Germany
2 Department of Pathology, Ruhr University, Bürkle-de-la Camp-Platz 1, Bochum D-44789, Germany
3 Immunogenetics Research Group, University of Rostock Medical School, Schillingallee 70, Rostock D-18055, Germany
4 Present address: Renal Section, Division of Medicine, Imperial College London, Du Cane Road, London W12 ONN, UK
* To whom correspondence should be addressed. Tel: +49 381 494 5066/5068; Fax: +49 381 494 5062; Email: brigitte.puetzer{at}med.uni-rostock.de
p53 family proteins carry on a wide spectrum of biological functions from differentiation, cell cycle arrest, apoptosis and chemosensitivity of tumors. Conversely, N-terminally truncated p73 (DNp73) functions as a potent inhibitor of all these tumor suppressor properties, implicating its participation in malignant transformation and oncogenesis. Several reports indicated considerable up-regulation of DNp73 in hepatocellular carcinoma (HCC) that correlates with reduced survival of patients, but little is known about the functional significance of DNp73 to tumorigenesis in vivo due to the lack of an appropriate model. To address this, we generated transgenic mice in which DNp73 expression is directed to the liver by the albumin promoter. Gene expression was tested by mRNA and protein analyses. Transgenic mice exhibited prominent hepatic histological abnormalities including increased hepatocyte proliferation resulting in preneoplastic lesions (liver cell adenomas) at 3–4 months. Among 12- to 20-month-old mice, 83% of animals developed hepatic carcinoma. HCC displayed a significant increase of hyperphosphorylated inactive retinoblastoma, whereas p53-regulated inhibitors of cell cycle progression were down-regulated in the tumors. Our data firmly establish the unique oncogenic capability of DNp73 to drive hepatocarcinogenesis in vivo, supporting its significance as a marker for disease severity in patients and as target for cancer prevention. This model offers new opportunities to further delineate DNp73-mediated liver oncogenesis but may also enable the development of more effective cancer therapies.
Abbreviations: HCC, hepatocellular carcinoma; Rb, retinoblastoma; TA, transactivation
These authors contributed equally to this work. Received August 22, 2007; revised October 10, 2007; accepted October 18, 2007.