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Tumor escape in a Wnt1-dependent mouse breast cancer model is enabled by p19Arf/p53 pathway lesions but not p16 Ink4a loss.

Authors: Debies, MT  Gestl, SA  Mathers, JL  Mikse, OR  Leonard, TL  Moody, SE  Chodosh, LA  Cardiff, RD  Gunther, EJ 
Citation: Debies MT, etal., J Clin Invest. 2008 Jan;118(1):51-63.
Pubmed: (View Article at PubMed) PMID:18060046
DOI: Full-text: DOI:10.1172/JCI33320

Breast cancers frequently progress or relapse during targeted therapy, but the molecular mechanisms that enable escape remain poorly understood. We elucidated genetic determinants underlying tumor escape in a transgenic mouse model of Wnt pathway-driven breast cancer, wherein targeted therapy is simulated by abrogating doxycycline-dependent Wnt1 transgene expression within established tumors. In mice with intact tumor suppressor pathways, tumors typically circumvented doxycycline withdrawal by reactivating Wnt signaling, either via aberrant (doxycycline-independent) Wnt1 transgene expression or via acquired somatic mutations in the gene encoding beta-catenin. Germline introduction of mutant tumor suppressor alleles into the model altered the timing and mode of tumor escape. Relapses occurring in the context of null Ink4a/Arf alleles (disrupting both the p16 Ink4a and p19 Arf tumor suppressors) arose quickly and rarely reactivated the Wnt pathway. In addition, Ink4a/Arf-deficient relapses resembled p53-deficient relapses in that both displayed morphologic and molecular hallmarks of an epithelial-to-mesenchymal transition (EMT). Notably, Ink4a/Arf deficiency promoted relapse in the absence of gross genomic instability. Moreover, Ink4a/Arf-encoded proteins differed in their capacity to suppress oncogene independence. Isolated p19 Arf deficiency mirrored p53 deficiency in that both promoted rapid, EMT-associated mammary tumor escape, whereas isolated p16 Ink4a deficiency failed to accelerate relapse. Thus, p19 Arf/p53 pathway lesions may promote mammary cancer relapse even when inhibition of a targeted oncogenic signaling pathway remains in force.

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CRRD Object Information
CRRD ID: 2289674
Created: 2008-02-06
Species: All species
Last Modified: 2008-02-06
Status: ACTIVE



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RGD is funded by grant HL64541 from the National Heart, Lung, and Blood Institute on behalf of the NIH.