Research article

The oncogenic fusion protein RUNX1-CBFA2T1 supports proliferation and inhibits senescence in t(8;21)-positive leukaemic cells

Natalia Martinez¹ , Bettina Drescher² , Heidemarie Riehle¹ , Claire Cullmann¹ , Hans-Peter Vornlocher³ , Arnold Ganser² , Gerhard Heil² , Alfred Nordheim¹ , Jürgen Krauter² and Olaf Heidenreich¹

¹  Department of Molecular Biology, Institute for Cell Biology, Faculty of Biology, University of Tübingen, Auf der Morgenstelle 15, 72076 Tübingen, Germany

²  Department of Haematology, Haemostaseology and Oncology, Hannover Medical School, 30625 Hannover, Germany

³  Alnylam Europe AG, Fritz-Hornschuch-Str. 9, 95326 Kulmbach, Germany

author email corresponding author email

BMC Cancer 2004, 4:44doi:10.1186/1471-2407-4-44

Published:	6 August 2004

Abstract

Background

The fusion protein RUNX1-CBFA2T1 associated with t(8;21)-positive acute myeloid leukaemia is a potent inhibitor of haematopoetic differentiation. The role of RUNX1-CBFA2T1 in leukaemic cell proliferation is less clear. We examined the consequences of siRNA-mediated RUNX1-CBFA2T1 depletion regarding proliferation and clonogenicity of t(8;21)-positive cell lines.

Methods

The t(8;21)-positive cell line Kasumi-1 was electroporated with RUNX1-CBFA2T1 or control siRNAs followed by analysis of proliferation, colony formation, cell cycle distribution, apoptosis and senescence.

Results

Electroporation of Kasumi-1 cells with RUNX1-CBFA2T1 siRNAs, but not with control siRNAs, resulted in RUNX1-CBFA2T1 suppression which lasted for at least 5 days. A single electroporation with RUNX1-CBFA2T1 siRNA severely diminished the clonogenicity of Kasumi-1 cells. Prolonged RUNX1-CBFA2T1 depletion inhibited proliferation in suspension culture and G1-S transition during the cell cycle, diminished the number of apoptotic cells, but induced cellular senescence. The addition of haematopoetic growth factors could not rescue RUNX1-CBFA2T1-depleted cells from senescence, and could only partially restore their clonogenicity.

Conclusions

RUNX1-CBFA2T1 supports the proliferation and expansion of t(8;21)-positive leukaemic cells by preventing cellular senescence. These findings suggest a central role of RUNX1-CBFA2T1 in the maintenance of the leukaemia. Therefore, RUNX1-CBFA2T1 is a promising and leukaemia-specific target for molecularly defined therapeutic approaches.