Impact of p53 loss on reversal and recurrence of conditional Wnt-induced tumorigenesis

  1. Edward J. Gunther1,2,3,4,
  2. Susan E. Moody1,2,3,4,
  3. George K. Belka1,2,3,4,
  4. Kristina T. Hahn1,2,3,4,
  5. Nathalie Innocent1,2,3,4,
  6. Katherine D. Dugan1,2,3,4,
  7. Robert D. Cardiff5, and
  8. Lewis A. Chodosh1,2,3,4,6
  1. 1Department of Cancer Biology, 2Department of Cell and Developmental Biology, 3Department of Medicine, 4Abramson Family Cancer Research Institute, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6160, USA; 5Center for Comparative Medicine, University of California, Davis, Davis, California 95616, USA

Abstract

Aberrant activation of Wnt signaling is oncogenic and has been implicated in a variety of human cancers. We have developed a doxycycline-inducible Wnt1 transgenic mouse model to determine the dependence of established mammary adenocarcinomas on continued Wnt signaling. Using this model we show that targeted down-regulation of the Wnt pathway results in the rapid disappearance of essentially all Wnt-initiated invasive primary tumors as well as pulmonary metastases. Tumor regression does not require p53 and occurs even in highly aneuploid tumors. However, despite the dependence of primary mammary tumors and metastases on continued Wnt signaling and the dispensability of p53 for tumor regression, we find that a substantial fraction of tumors progress to a Wnt-independent state and that p53 suppresses this process. Specifically, loss of one p53 allele dramatically facilitates the progression of mammary tumors to aWnt1-independent state both by impairing the regression of primary tumors following doxycycline withdrawal and by promoting the recurrence of fully regressed tumors in the absence of doxycycline. Thus, although p53 itself is dispensable for tumor regression, it nevertheless plays a critical role in the suppression of tumor recurrence. Our findings demonstrate that although even advanced stages of epithelial malignancy remain dependent upon continued Wnt signaling for maintenance and growth, loss of p53 facilitates tumor escape and the acquisition of oncogene independence.

Keywords

Footnotes

  • 6 Corresponding author.

  • E-MAIL chodosh{at}mail.med.upenn.edu; FAX (215) 573-6725.

  • Article and publication are at http://www.genesdev.org/cgi/doi/10.1101/gad.1051603.

    • Received October 18, 2002.
    • Accepted December 31, 2002.
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