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- Title
Elimination of C/EBPalpha through the ubiquitin-proteasome system promotes the development of liver cancer in mice.
- Authors
Guo-Li Wang; Xiurong Shi; Haefliger, Simon; Jingling Jin; Major, Angela; Iakova, Polina; Finegold, Milton; Timchenko, Nikolai A.; Wang, Guo-Li; Shi, Xiurong; Jin, Jingling
- Abstract
Despite significant advancements in our understanding of cancer development, the molecular mechanisms that underlie the formation of liver cancer remain largely unknown. C/EBPalpha is a transcription factor that regulates liver quiescence. Phosphorylation of C/EBPalpha at serine 193 (S193-ph) is upregulated in older mice and is thought to contribute to age-associated liver dysfunction. Because development of liver tumors is associated with increasing age, we investigated the role of S193-ph in the development of liver cancer using knockin mice expressing a phospho-mimetic aspartic acid residue in place of serine at position 193 (S193D) of C/EBPalpha. The S193D isoform of C/EBPalpha was able to completely inhibit liver proliferation in vivo after partial hepatectomy. However, treatment of these mice with diethylnitrosamine/phenobarbital (DEN/PB), which induces formation of liver cancer, actually resulted in earlier development of liver tumors. DEN/PB treatment was associated with specific degradation of both the S193-ph and S193D isoforms of C/EBPalpha through activation of the ubiquitinproteasome system (UPS). The mechanism of UPS-mediated elimination of C/EBPalpha during carcinogenesis involved elevated levels of gankyrin, a protein that was found to interact with the S193-ph isoform of C/EBPalpha and target it for UPS-mediated degradation. This study identifies a molecular mechanism that supports the development of liver cancer in older mice and potential therapeutic targets for the prevention of liver cancer.
- Subjects
UBIQUITIN; LIVER cancer prevention; LABORATORY mice; PHOSPHORYLATION; HEPATECTOMY; CARCINOGENESIS; PROTEIN metabolism; SERINE metabolism; ANIMAL experimentation; LIVER; LIVER tumors; MICE; PROTEINS; PROTEOLYTIC enzymes; RESEARCH funding; TRANSCRIPTION factors; SERINE
- Publication
Journal of Clinical Investigation, 2010, Vol 120, Issue 7, p2549
- ISSN
0021-9738
- Publication type
journal article
- DOI
10.1172/JCI41933