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

Van Ta, Marjolein De Jong - de Bruijn, PJ (Petra) ter Brugge, Jan piet Hamburg, Hans Diepstraten, Pieter fokko Loo, Rogier Kersseboom, Rudi Hendriks

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The adapter protein Slp65 is a key component of the precursor-B (pre-B) cell receptor. Slp65-deficient mice spontaneously develop pre-B cell leukemia, but the mechanism by which Slp65(-/-) pre-B cells become malignant is unknown. Loss of Btk, a Tec-family kinase that cooperates with Slp65 as a tumor suppressor, synergizes with deregulation of the c-Myc oncogene during lymphoma formation. Here, we report that the presence of the immunoglobulin heavy chain transgene V(H)81X prevented tumor development in Btk(-/-)Slp65(-/-) mice. This finding paralleled the reported effect of a human immunoglobulin heavy chain transgene on lymphoma development in E mu-myc mice, expressing transgenic c-Myc. Because activation of c-Myc strongly selects for spontaneous inactivation of the p19(Arf)-Mdm2-p53 tumor suppressor pathway, we investigated whether disruption of this pathway is a common alteration in Slp65(-/-) pre-B cell tumors. We found that combined loss of Slp65 and p53 in mice transformed pre-B cells very efficiently. Aberrations in p19(Arf), Mdm2, or p53 expression were found in all Slp65(-/-)(n = 17) and Btk(-/-)Slp65(-/-)(n = 32) pre-B cell leukemias analyzed. In addition, 9 of 10 p53(-/-)Slp65(-/-) pre-B cell leukemias manifested significant Mdm2 protein expression. These data indicate that malignant transformation of Slp65(-/-) pre-B cells involves disruption of the p19(Arf)-Mdm2-p53 tumor suppressor pathway. (Blood. 2010; 115: 1385-1393)
Original languageUndefined/Unknown
Pages (from-to)1385-1393
Number of pages9
Issue number7
Publication statusPublished - 2010

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