title: Impact of p53 loss on reversal and recurrence of conditional Wnt-induced tumorigenesis.
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 a Wnt1-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.
authors.affiliation: Department of Cancer Biology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6160, USA.
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Gunther
authors.forename: Susan E
authors.initials: SE
authors.lastname: Moody
authors.forename: George K
authors.initials: GK
authors.lastname: Belka
authors.forename: Kristina T
authors.initials: KT
authors.lastname: Hahn
authors.forename: Nathalie
authors.initials: N
authors.lastname: Innocent
authors.forename: Katherine D
authors.initials: KD
authors.lastname: Dugan
authors.forename: Robert D
authors.initials: RD
authors.lastname: Cardiff
authors.forename: Lewis A
authors.initials: LA
authors.lastname: Chodosh
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D000782:Aneuploidy; D000818:Animals; D015536:Down-Regulation; D004318:Doxycycline / Q000494:pharmacology; D005260:Female; D008175:Lung Neoplasms / Q000235:genetics / Q000473:pathology / Q000556:secondary; D008325:Mammary Neoplasms, Experimental / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008822:Mice, Transgenic; D009364:Neoplasm Recurrence, Local / Q000235:genetics*; D009365:Neoplasm Regression, Spontaneous / Q000235:genetics*; D009928:Organ Specificity; D011518:Proto-Oncogene Proteins / Q000187:drug effects / Q000502:physiology*; D015398:Signal Transduction; D016159:Tumor Suppressor Protein p53 / Q000235:genetics* / Q000378:metabolism; D051153:Wnt Proteins; D051155:Wnt1 Protein; D029961:Zebrafish Proteins
chemical_list: D011518:Proto-Oncogene Proteins; D016159:Tumor Suppressor Protein p53; D051153:Wnt Proteins; D051155:Wnt1 Protein; C495246:Wnt1 protein, mouse; D029961:Zebrafish Proteins; D004318:Doxycycline