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Cancer Res. 2010 Jul 1;70(13):5305-15. doi: 10.1158/0008-5472.CAN-09-3399. Epub 2010 Jun 8.

The phosphoinositide 3-kinase regulatory subunit p85alpha can exert tumor suppressor properties through negative regulation of growth factor signaling.

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1
Joslin Diabetes Center and Department of Pathology, Harvard Medical School, Boston, Massachusetts 02215, USA.

Abstract

Phosphoinositide 3-kinase (PI3K) plays a critical role in tumorigenesis, and the PI3K p85 regulatory subunit exerts both positive and negative effects on signaling. Expression of Pik3r1, the gene encoding p85, is decreased in human prostate, lung, ovarian, bladder, and liver cancers, consistent with the possibility that p85 has tumor suppressor properties. We tested this hypothesis by studying mice with a liver-specific deletion of the Pik3r1 gene. These mice exhibited enhanced insulin and growth factor signaling and progressive changes in hepatic pathology, leading to the development of aggressive hepatocellular carcinomas with pulmonary metastases. Liver tumors that arose exhibited markedly elevated levels of phosphatidylinositol (3,4,5)-trisphosphate, along with Akt activation and decreased PTEN expression, at both the mRNA and protein levels. Together, these results substantiate the concept that the p85 subunit of PI3K has a tumor-suppressive role in the liver and possibly other tissues.

PMID:
20530665
PMCID:
PMC3204358
DOI:
10.1158/0008-5472.CAN-09-3399
[Indexed for MEDLINE]
Free PMC Article

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