Document Detail

The expression of the tumour suppressor HBP1 is down-regulated by growth factors via the PI3K/PKB/FOXO pathway.
MedLine Citation:
PMID:  24762137     Owner:  NLM     Status:  In-Data-Review    
Growth factors inactivate the FOXO (forkhead box O) transcription factors through PI3K (phosphoinositide 3-kinase) and PKB (protein kinase B). By comparing microarray data from multiple model systems, we identified HBP1 (high-mobility group-box protein 1) as a novel downstream target of this pathway. HBP1 mRNA was down-regulated by PDGF (platelet-derived growth factor), FGF (fibroblast growth factor), PI3K and PKB, whereas it was up-regulated by FOXO factors. This observation was confirmed in human and murine fibroblasts as well as in cell lines derived from leukaemia, breast adenocarcinoma and colon carcinoma. Bioinformatics analysis led to the identification of a conserved consensus FOXO-binding site in the HBP1 promoter. By luciferase activity assay and ChIP, we demonstrated that FOXO bound to this site and regulated the HBP1 promoter activity in a PI3K-dependent manner. Silencing of HBP1 by shRNA increased the proliferation of human fibroblasts in response to growth factors, suggesting that HBP1 limits cell growth. Finally, by analysing a transcriptomics dataset from The Cancer Genome Atlas, we observed that HBP1 expression was lower in breast tumours that had lost FOXO expression. In conclusion, HBP1 is a novel target of the PI3K/FOXO pathway and controls cell proliferation in response to growth factors.
Alexandra Coomans de Brachène; Emeline Bollaert; Astrid Eijkelenboom; Audrey de Rocca Serra; Kristan E van der Vos; Boudewijn M T Burgering; Paul J Coffer; Ahmed Essaghir; Jean-Baptiste Demoulin
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The Biochemical journal     Volume:  460     ISSN:  1470-8728     ISO Abbreviation:  Biochem. J.     Publication Date:  2014 May 
Date Detail:
Created Date:  2014-04-25     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  2984726R     Medline TA:  Biochem J     Country:  England    
Other Details:
Languages:  eng     Pagination:  25-34     Citation Subset:  IM    
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