Ebf1 or Pax5 haploinsufficiency synergizes with STAT5 activation to initiate acute lymphoblastic leukemia.

J Exp Med, 2011/6/06;208(6):1135-49.

Heltemes-Harris LM[1], Willette MJ, Ramsey LB, Qiu YH, Neeley ES, Zhang N, Thomas DA, Koeuth T, Baechler EC, Kornblau SM, Farrar MA

Affiliations

PMID: 21606506DOI: 10.1084/jem.20101947

Impact factor: 17.579

Abstract
As STAT5 is critical for the differentiation, proliferation, and survival of progenitor B cells, this transcription factor may play a role in acute lymphoblastic leukemia (ALL). Here, we show increased expression of activated signal transducer and activator of transcription 5 (STAT5), which is correlated with poor prognosis, in ALL patient cells. Mutations in EBF1 and PAX5, genes critical for B cell development have also been identified in human ALL. To determine whether mutations in Ebf1 or Pax5 synergize with STAT5 activation to induce ALL, we crossed mice expressing a constitutively active form of STAT5 (Stat5b-CA) with mice heterozygous for Ebf1 or Pax5. Haploinsufficiency of either Pax5 or Ebf1 synergized with Stat5b-CA to rapidly induce ALL in 100% of the mice. The leukemic cells displayed reduced expression of both Pax5 and Ebf1, but this had little effect on most EBF1 or PAX5 target genes. Only a subset of target genes was deregulated; this subset included a large percentage of potential tumor suppressor genes and oncogenes. Further, most of these genes appear to be jointly regulated by both EBF1 and PAX5. Our findings suggest a model whereby small perturbations in a self-reinforcing network of transcription factors critical for B cell development, specifically PAX5 and EBF1, cooperate with STAT5 activation to initiate ALL.
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