Stat5 exerts distinct, vital functions in the cytoplasm and nucleus of Bcr-Abl+ K562 and Jak2(V617F)+ HEL leukemia cells

  • Signal transducers and activators of transcription (Stats) play central roles in the conversion of extracellular signals, e.g., cytokines, hormones and growth factors, into tissue and cell type specific gene expression patterns. In normal cells, their signaling potential is strictly limited in extent and duration. The persistent activation of Stat3 or Stat5 is found in many human tumor cells and contributes to their growth and survival. Stat5 activation plays a pivotal role in nearly all hematological malignancies and occurs downstream of oncogenic kinases, e.g., Bcr-Abl in chronic myeloid leukemias (CML) and Jak2(V617F) in other myeloproliferative diseases (MPD). We defined the mechanisms through which Stat5 affects growth and survival of K562 cells, representative of Bcr-Abl positive CML, and HEL cells, representative for Jak2(V617F) positive acute erythroid leukemia. In our experiments we suppressed the protein expression levels of Stat5a and Stat5b through shRNA mediated downregulation and demonstrated the dependence of cell survival on the presence of Stat5. Alternatively, we interfered with the functional capacities of the Stat5 protein through the interaction with a Stat5 specific peptide ligand. This ligand is a Stat5 specific peptide aptamer construct which comprises a 12mer peptide integrated into a modified thioredoxin scaffold, S5-DBD-PA. The peptide sequence specifically recognizes the DNA binding domain (DBD) of Stat5. Complex formation of S5-DBD-PA with Stat5 causes a strong reduction of P-Stat5 in the nuclear fraction of Bcr-Abl-transformed K562 cells and a suppression of Stat5 target genes. Distinct Stat5 mediated survival mechanisms were detected in K562 and Jak2(V617F)-transformed HEL cells. Stat5 is activated in the nuclear and cytosolic compartments of K562 cells and the S5-DBD-PA inhibitor most likely affects the viability of Bcr-Abl+ K562 cells through the inhibition of canonical Stat5 induced target gene transcription. In HEL cells, Stat5 is predominantly present in the cytoplasm and the survival of the Jak2(V617F)+ HEL cells is impeded through the inhibition of the cytoplasmic functions of Stat5.

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Metadaten
Author:Axel Weber, Corina Borghouts, Christian BrendelGND, Richard Moriggl, Natalia Delis, Boris Brill, Vida VafaizadehORCiDGND, Bernd GronerGND
URN:urn:nbn:de:hebis:30:3-543358
DOI:https://doi.org/10.3390/cancers7010503
ISSN:2072-6694
Parent Title (English):Cancers
Publisher:MDPI
Place of publication:Basel
Document Type:Article
Language:English
Date of Publication (online):2015/03/19
Date of first Publication:2015/03/19
Publishing Institution:Universit├Ątsbibliothek Johann Christian Senckenberg
Release Date:2020/05/05
Tag:Bcr-Abl; Jak2(V617F); RNA interference (RNAi); canonical/non-canonical; chronic myeloid leukemia (CML); human erythroid leukemia (HEL); peptide aptamer (PA); protein/lentiviral transduction; signal transducer and activator of transcription 5 (Stat5)
Volume:7
Issue:1
Page Number:35
First Page:503
Last Page:537
Note:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
HeBIS-PPN:465065635
Institutes:Medizin / Medizin
Angeschlossene und kooperierende Institutionen / Georg-Speyer-Haus
Dewey Decimal Classification:6 Technik, Medizin, angewandte Wissenschaften / 61 Medizin und Gesundheit / 610 Medizin und Gesundheit
Sammlungen:Universit├Ątspublikationen
Licence (German):License LogoCreative Commons - Namensnennung 4.0