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SMAD4 binds HOXA9 in the cytoplasm and protects primitive hematopoietic cells against nuclear activation by HOXA9 and leukemia transformation.

Author:
  • Ronan Quere
  • Göran Karlsson
  • Falk Hertwig
  • Marianne Rissler
  • Beata Lindqvist
  • Thoas Fioretos
  • Peter Vandenberghe
  • Marilyn L Slovak
  • Jörg Cammenga
  • Stefan Karlsson
Publishing year: 2011
Language: English
Pages: 5918-5930
Publication/Series: Blood
Volume: 117
Document type: Journal article
Publisher: American Society of Hematology

Abstract english

We studied leukemic stem cells (LSCs) in a Smad4(-/-) mouse model of acute myelogenous leukemia (AML) induced either by the HOXA9 gene or by the fusion oncogene NUP98-HOXA9. While HOXA9-SMAD4 complexes accumulate in the cytoplasm of normal hematopoietic stem- and progenitor cells (HSPCs) transduced with these oncogenes, there is no cytoplasmic accumulation of HOXA9 in Smad4(-/-) HSPCs and as a consequence increased levels of HOXA9 accumulate in the nucleus leading to increased immortalization in vitro. Loss of Smad4 accelerates the development of leukemia in vivo due to an increase in transformation of HSPCs. Therefore, the cytoplasmic binding of HOXA9 by SMAD4 is a mechanism to protect HOXA9-induced transformation of normal HSPCs. Since Smad4 is a potent tumor suppressor involved in growth control, we developed a strategy to modify the subcellular distribution of SMAD4. We successfully disrupted the interaction between HOXA9 and SMAD4 to activate the TGF-beta pathway and apoptosis, leading to a loss of LSCs. Together, these findings reveal a major role for Smad4 in the negative regulation of leukemia initiation and maintenance induced by HOXA9/NUP98-HOXA9 and provide strong evidence that antagonizing SMAD4 stabilization by these oncoproteins might be a promising novel therapeutic approach in leukemia.

Keywords

  • Hematology

Other

Published
  • Hematopoiesis and Gene Therapy
  • ISSN: 1528-0020
Thoas Fioretos
E-mail: thoas.fioretos [at] med.lu.se

Principal investigator

Division of Clinical Genetics

+46 46 222 45 95

+46 70 334 33 67

BMC C13

66