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Malignant transformation of Slp65-deficient pre-B cells involves disruption of the Arf-Mdm2-p53 tumor suppressor

Van B T Ta1, Marjolein J W de Bruijn, Petra J ter Brugge

  • 1Department of Immunology, Erasmus MC Rotterdam, Rotterdam, The Netherlands.

Blood
|December 17, 2009
PubMed

Insights

The adapter protein Slp65 is crucial for preventing pre-B cell leukemia. Its absence leads to malignant transformation, often involving the p19(Arf)-Mdm2-p53 tumor suppressor pathway.

Area of Science:

  • Immunology
  • Oncology
  • Molecular Biology

Background:

  • The adapter protein Slp65 is essential for the precursor-B (pre-B) cell receptor function.
  • Slp65-deficient mice develop pre-B cell leukemia, but the underlying mechanisms remain unclear.
  • Btk kinase and c-Myc oncogene deregulation cooperate with Slp65 loss in lymphoma development.

Purpose of the Study:

  • To investigate the mechanism of malignant transformation in Slp65-deficient pre-B cells.
  • To determine the role of the p19(Arf)-Mdm2-p53 tumor suppressor pathway in Slp65-associated leukemia.
  • To explore the impact of immunoglobulin heavy chain transgenes on tumor development.

Main Methods:

  • Analysis of tumor development in Btk(-/-)Slp65(-/-) mice with immunoglobulin heavy chain transgenes.
  • Investigation of the p19(Arf)-Mdm2-p53 pathway in Slp65(-/-) and Btk(-/-)Slp65(-/-) pre-B cell leukemias.
  • Assessment of pre-B cell transformation efficiency in mice with combined Slp65 and p53 loss.

Main Results:

  • The V(H)81X immunoglobulin heavy chain transgene prevented tumor development in Btk(-/-)Slp65(-/-) mice.
  • Combined loss of Slp65 and p53 efficiently transformed pre-B cells.
  • All analyzed Slp65(-/-) and Btk(-/-)Slp65(-/-) leukemias showed aberrations in the p19(Arf)-Mdm2-p53 pathway.
  • A majority of p53(-/-)Slp65(-/-) leukemias exhibited significant Mdm2 protein expression.

Conclusions:

  • Malignant transformation of Slp65(-/-) pre-B cells is strongly associated with disruption of the p19(Arf)-Mdm2-p53 tumor suppressor pathway.
  • The p19(Arf)-Mdm2-p53 pathway is a critical component in the development of pre-B cell leukemia when Slp65 is absent.

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