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The MDM2 antagonist nutlin-3 sensitizes p53-null neuroblastoma cells to doxorubicin via E2F1 and TAp73

Susan K Peirce1, Harry W Findley

  • 1Department of Pediatrics, Division of Hematology and Oncology, Aflac Cancer Center and Blood Disorders Service, Emory University School of Medicine, Atlanta, GA 30322, USA. susan_peirce@oz.ped.emory.edu

International Journal of Oncology
|April 11, 2009
PubMed

Insights

Nutlin-3, a drug targeting MDM2, sensitizes chemoresistant neuroblastoma (NB) cells to doxorubicin by activating TAp73 and E2F1. This p53-independent approach offers a potential treatment strategy for high-risk neuroblastoma.

Area of Science:

  • Pediatric Oncology
  • Molecular Oncology
  • Cancer Therapeutics

Background:

  • Neuroblastoma (NB) is a common childhood cancer with heterogeneous behavior.
  • High-risk NB in patients over 1 year old often shows p53 pathway alterations and chemoresistance.
  • Current treatments face challenges due to drug resistance and p53 dysfunction.

Purpose of the Study:

  • To investigate if nutlin-3 can sensitize p53-null, doxorubicin-resistant neuroblastoma cells to doxorubicin.
  • To elucidate the p53-independent mechanisms underlying nutlin-3's action in combination therapy.
  • To explore potential therapeutic strategies for chemoresistant neuroblastoma.

Main Methods:

  • Utilized a p53-null, doxorubicin-resistant neuroblastoma cell line (LA155N).
  • Treated cells with nutlin-3 and doxorubicin, alone and in combination.
  • Assessed protein levels (TAp73, E2F1, PUMA) and effects on cell proliferation and apoptosis.
  • Performed knockdown studies for TAp73 and E2F1 to confirm their roles.

Main Results:

  • Nutlin-3 upregulated TAp73 and E2F1 protein levels in LA155N cells.
  • The combination of nutlin-3 and doxorubicin synergistically inhibited cell proliferation and induced apoptosis.
  • TAp73 and E2F1 were crucial for the observed sensitization, with their knockdown reducing the combined effect.
  • PUMA expression was induced by the combination treatment, dependent on TAp73 and E2F1.

Conclusions:

  • Nutlin-3 can overcome doxorubicin resistance in p53-deficient neuroblastoma cells.
  • The mechanism involves nutlin-3 releasing TAp73 and E2F1 from MDM2 inhibition, leading to doxorubicin-induced PUMA expression and apoptosis.
  • This p53-independent pathway represents a promising therapeutic avenue for chemoresistant neuroblastoma.

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