title: Irs2 inactivation suppresses tumor progression in Pten+/- mice.
abstract: Mutations in the phosphatase and tensin homologue (PTEN)/phosphatidylinositol-3 kinase-alpha (PI3K) signaling pathway are frequently found in human cancer. In addition, Pten(+/-) mice develop tumors in multiple organs because of the activation of the PI3K signaling cascade. Because activation of PI3K signaling leads to feedback inhibition of insulin receptor substrate-2 (IRS2) expression, an upstream activator of PI3K, we therefore anticipated that IRS2 expression would be low in tumors that lack PTEN. Surprisingly, however, an elevation of IRS2 was often detected in tumor samples in which PTEN levels were compromised. To determine the potential contribution of Irs2 to tumor progression, Pten(+/-) mice were crossed with Irs2(+/-) mice. Deletion of Irs2 did not affect the initiation of neoplasia found in Pten(+/-) mice but suppressed cancer cell growth, proliferation, and invasion through the basement membrane. Deletion of Irs2 also attenuated the expression of Myc in prostatic intraepithelial neoplasia in Pten(+/-) mice. In addition, the expression levels of IRS2 and MYC were highly correlated in human prostate cancer, and IRS2 could stimulate MYC expression in cultured cells. Our findings provide evidence that the PI3K-activating adaptor Irs2 contributes to tumor progression in Pten(+/-) mice by stimulating both Myc and DNA synthesis.
authors.affiliation: Institute for Cancer Genetics, College of Physicians and Surgeons, Columbia University, New York, New York, USA.
authors.forename: Matthias
authors.initials: M
authors.lastname: Szabolcs
authors.forename: Megan
authors.initials: M
authors.lastname: Keniry
authors.forename: Laura
authors.initials: L
authors.lastname: Simpson
authors.forename: Latarsha J
authors.initials: LJ
authors.lastname: Reid
authors.forename: Susan
authors.initials: S
authors.lastname: Koujak
authors.forename: Sarah C
authors.initials: SC
authors.lastname: Schiff
authors.forename: Giselle
authors.initials: G
authors.lastname: Davidian
authors.forename: Scott
authors.initials: S
authors.lastname: Licata
authors.forename: Sofia
authors.initials: S
authors.lastname: Gruvberger-Saal
authors.forename: Vundavalli V V S
authors.initials: VV
authors.lastname: Murty
authors.forename: Subhadra
authors.initials: S
authors.lastname: Nandula
authors.forename: Argiris
authors.initials: A
authors.lastname: Efstratiadis
authors.forename: Jake A
authors.initials: JA
authors.lastname: Kushner
authors.forename: Morris F
authors.initials: MF
authors.lastname: White
authors.forename: Ramon
authors.initials: R
authors.lastname: Parsons
mesh_terms: D000818:Animals; D015153:Blotting, Western; D045744:Cell Line, Tumor; D018450:Disease Progression; D016889:Endometrial Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D055504:Insulin Receptor Substrate Proteins / Q000235:genetics* / Q000378:metabolism*; D008297:Male; D051379:Mice; D008817:Mice, Mutant Strains; D009369:Neoplasms / Q000235:genetics* / Q000378:metabolism* / Q000473:pathology; D051059:PTEN Phosphohydrolase / Q000235:genetics* / Q000378:metabolism*; D011471:Prostatic Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism; D014162:Transfection
chemical_list: D055504:Insulin Receptor Substrate Proteins; C526298:Irs2 protein, mouse; D016271:Proto-Oncogene Proteins c-myc; D051059:PTEN Phosphohydrolase; C487757:Pten protein, mouse