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Science. 2009 Sep 4;325(5945):1261-5. doi: 10.1126/science.1173569.

Activation of the PI3K pathway in cancer through inhibition of PTEN by exchange factor P-REX2a.

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  • 1Institute for Cancer Genetics and Herbert Irving Comprehensive Cancer Center, Columbia University, 1130 St. Nicholas Avenue, New York, NY 10032, USA.

Abstract

PTEN (phosphatase and tensin homolog on chromosome 10) is a tumor suppressor whose cellular regulation remains incompletely understood. We identified phosphatidylinositol 3,4,5-trisphosphate RAC exchanger 2a (P-REX2a) as a PTEN-interacting protein. P-REX2a mRNA was more abundant in human cancer cells and significantly increased in tumors with wild-type PTEN that expressed an activated mutant of PIK3CA encoding the p110 subunit of phosphoinositide 3-kinase subunit alpha (PI3Kalpha). P-REX2a inhibited PTEN lipid phosphatase activity and stimulated the PI3K pathway only in the presence of PTEN. P-REX2a stimulated cell growth and cooperated with a PIK3CA mutant to promote growth factor-independent proliferation and transformation. Depletion of P-REX2a reduced amounts of phosphorylated AKT and growth in human cell lines with intact PTEN. Thus, P-REX2a is a component of the PI3K pathway that can antagonize PTEN in cancer cells.

PMID:
19729658
[PubMed - indexed for MEDLINE]
PMCID:
PMC2936784
Free PMC Article
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