Send to

Choose Destination
Oncogene. 2003 Oct 2;22(43):6725-38.

The proto-oncoprotein c-Fos negatively regulates hepatocellular tumorigenesis.

Author information

Institute of Cancer Research, University of Vienna, Borschke-Gasse 8a, A-1090 Vienna, Austria.


Hepatocytes adopt an invasive and metastatic phenotype caused by the cooperation of transforming growth factor (TGF)-beta and oncogenic Ha-Ras. In the initial phase of this process, c-Fos is rapidly induced by TGF-beta, but then decreases to undetectable levels. Here, we investigated the functional implications of c-Fos activation and its contribution to hepatocellular tumorigenesis. By employing conditional c-Fos expression, we observed that continuous activation of c-Fos and consequently AP-1 activity leads to depolarization of differentiated murine epithelial hepatocytes. Most remarkably, this change in morphology was associated with inhibition of proliferation and induction of cell death. Coexpression of antiapoptotic Bcl-XL or scavenging of reactive oxygen species was sufficient to prevent the c-Fos-mediated phenotype. In contrast, the cooperation of c-Fos with oncogenic Ha-Ras or a Ras mutant selectively activating the MAPK pathway even enhanced c-Fos-induced effects. Showing the negative role in hepatocellular tumorigenesis, c-Fos repressed oncogenic Ras-driven anchorage-independent growth in vitro and strongly suppressed tumour formation in vivo. Taken together, we demonstrate that c-Fos modulates plasticity of epithelial hepatocytes and acts tumour suppressive in neoplastic hepatocytes by stimulating cell cycle inhibition and cell death.

[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Nature Publishing Group
Loading ...
Support Center