Author of

• 11454

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  P2.01 - Poster Session 2 - Cancer Biology (ID 145)

  • Event: WCLC 2013
  • Type: Poster Session
  • Track: Biology
  • Presentations: 1
  • Moderators:
  • Coordinates: 10/29/2013, 09:30 - 16:30, Exhibit Hall, Ground Level

  • 11458

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    P2.01-004 - Type of P53 mutation influences oncogenic potential and spectrum of associated K-ras mutations in lung specific transgenic mice. (ID 1972)

    09:30 - 09:30  |  Author(s): H. Ding
    • Abstract

    Background
    p53 mutations have been categorized as type I (contact) and type II (conformational) mutations. Differential effects of type I vs. type II p53 mutations in spontaneous lung tumor formation, and their relationship with secondary genetic alterations have not been previously reported. .

    Methods
    We evaluated the potential of two common type I (273H) and type II (175H) mutations under the transcriptional control of the human surfactant protein C (SP-C) promoter to induce lung tumors in transgenic mice. Necropsies of 138 non-transgenic, 207 SP-C-p53-273H and 171 SPC-p53-175H transgenic mice in progressive age cohorts were performed.

    Results
    Ninety-one tumors, all adenocarcinomas, were observed; 8 (5.8%), 37 (17.9%) and 46 (26.9%) in non-transgenics, p53-273H and p53-175H, respectively (non-transgenic vs. 273H, p=0.010; non-transgenic vs. 175H, p= 0.0003; logistic regression). Type II p53 mutants had an earlier onset of tumors; 23 of 98 p53-175H mice developed tumors before the age of 13 months, compared to 7 of 108 p53-273H mice (p=0.012, logistic regression). K-ras mutations occurred in a substantial proportion (21 of 50, 42%) of murine lung tumors sequenced. For both the non-transgenic and the p53-273H transgenics, tumor K-ras codon 12-13 mutations occurred after 13 months with a peak incidence at 16–18 months. However, for the p53-175H transgenics K-ras codon 12-13 mutations were observed as early as six months, with a peak incidence between the ages of 10-12 months. Codons 12-13 were the predominant location in p53-175H transgenics (6 of 7), whereas codon 61 (6 of 10) was more common in p53-273H transgenics.

    Conclusion
    The observation of accelerated tumor onset, early appearance and high frequency of K-ras codon 12-13 mutations in type II p53-175H mice confirms the enhanced oncogenic function of conformational p53 mutations, and the gains in early genetic instability for tumors containing these mutations compared to contact mutations. These data would suggest that not only the presence, but also the type of p53 mutations in human lung cancer should be considered when evaluating prognosis and developing treatment strategies for this malignancy. These mice develop a single-lung tumor that is easy to follow with CT imaging. Thus, these animal models provide a framework for evaluation of the effects of these mutations on response to standard and novel anticancer treatment interventions.