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J Exp Med. 2009 Aug 3;206(8):1739-53. doi: 10.1084/jem.20090004. Epub 2009 Jul 20.

Pre-B cell receptor-mediated cell cycle arrest in Philadelphia chromosome-positive acute lymphoblastic leukemia requires IKAROS function.

Author information

1
Leukemia and Lymphoma Program, Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA 90027, USA.

Abstract

B cell lineage acute lymphoblastic leukemia (ALL) arises in virtually all cases from B cell precursors that are arrested at pre-B cell receptor-dependent stages. The Philadelphia chromosome-positive (Ph(+)) subtype of ALL accounts for 25-30% of cases of adult ALL, has the most unfavorable clinical outcome among all ALL subtypes and is defined by the oncogenic BCR-ABL1 kinase and deletions of the IKAROS gene in >80% of cases. Here, we demonstrate that the pre-B cell receptor functions as a tumor suppressor upstream of IKAROS through induction of cell cycle arrest in Ph(+) ALL cells. Pre-B cell receptor-mediated cell cycle arrest in Ph(+) ALL cells critically depends on IKAROS function, and is reversed by coexpression of the dominant-negative IKAROS splice variant IK6. IKAROS also promotes tumor suppression through cooperation with downstream molecules of the pre-B cell receptor signaling pathway, even if expression of the pre-B cell receptor itself is compromised. In this case, IKAROS redirects oncogenic BCR-ABL1 tyrosine kinase signaling from SRC kinase-activation to SLP65, which functions as a critical tumor suppressor downstream of the pre-B cell receptor. These findings provide a rationale for the surprisingly high frequency of IKAROS deletions in Ph(+) ALL and identify IKAROS-mediated cell cycle exit as the endpoint of an emerging pathway of pre-B cell receptor-mediated tumor suppression.

PMID:
19620627
PMCID:
PMC2722172
DOI:
10.1084/jem.20090004
[Indexed for MEDLINE]
Free PMC Article

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