PLoS ONE (Jan 2013)

Engagement of SIRPα inhibits growth and induces programmed cell death in acute myeloid leukemia cells.

  • Mahban Irandoust,
  • Julian Alvarez Zarate,
  • Isabelle Hubeek,
  • Ellen M van Beek,
  • Karin Schornagel,
  • Aart J F Broekhuizen,
  • Mercan Akyuz,
  • Arjan A van de Loosdrecht,
  • Ruud Delwel,
  • Peter J Valk,
  • Edwin Sonneveld,
  • Pamela Kearns,
  • Ursula Creutzig,
  • Dirk Reinhardt,
  • Eveline S J M de Bont,
  • Eva A Coenen,
  • Marry M van den Heuvel-Eibrink,
  • C Michel Zwaan,
  • Gertjan J L Kaspers,
  • Jacqueline Cloos,
  • Timo K van den Berg

DOI
https://doi.org/10.1371/journal.pone.0052143
Journal volume & issue
Vol. 8, no. 1
p. e52143

Abstract

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BackgroundRecent studies show the importance of interactions between CD47 expressed on acute myeloid leukemia (AML) cells and the inhibitory immunoreceptor, signal regulatory protein-alpha (SIRPα) on macrophages. Although AML cells express SIRPα, its function has not been investigated in these cells. In this study we aimed to determine the role of the SIRPα in acute myeloid leukemia.Design and methodsWe analyzed the expression of SIRPα, both on mRNA and protein level in AML patients and we further investigated whether the expression of SIRPα on two low SIRPα expressing AML cell lines could be upregulated upon differentiation of the cells. We determined the effect of chimeric SIRPα expression on tumor cell growth and programmed cell death by its triggering with an agonistic antibody in these cells. Moreover, we examined the efficacy of agonistic antibody in combination with established antileukemic drugs.ResultsBy microarray analysis of an extensive cohort of primary AML samples, we demonstrated that SIRPα is differentially expressed in AML subgroups and its expression level is dependent on differentiation stage, with high levels in FAB M4/M5 AML and low levels in FAB M0-M3. Interestingly, AML patients with high SIRPα expression had a poor prognosis. Our results also showed that SIRPα is upregulated upon differentiation of NB4 and Kasumi cells. In addition, triggering of SIRPα with an agonistic antibody in the cells stably expressing chimeric SIRPα, led to inhibition of growth and induction of programmed cell death. Finally, the SIRPα-derived signaling synergized with the activity of established antileukemic drugs.ConclusionsOur data indicate that triggering of SIRPα has antileukemic effect and may function as a potential therapeutic target in AML.