Identification of CD25 as STAT5-dependent growth-regulator of Leukemic stem cells in Ph+ CML

Sadovnik, I. et al. (2016) Identification of CD25 as STAT5-dependent growth-regulator of Leukemic stem cells in Ph+ CML. Clinical Cancer Research, 22(8), pp. 2051-2061. (doi: 10.1158/1078-0432.CCR-15-0767) (PMID:26607600)

Abstract

PURPOSE In chronic myeloid leukemia (CML), leukemic stem cells (LSCs) represent a critical target of therapy. However, little is known about markers and targets expressed by LSCs. The aim of this project was to identify novel interesting markers of CML LSCs. EXPERIMENTAL DESIGN CML LSCs were examined by flow cytometry, qPCR, and various bioassays. In addition, we examined the multipotent CD25+ CML cell line KU812. RESULTS In contrast to normal hematopoietic stem cells, CD34+/CD38- CML LSCs expressed the interleukin-2 receptor alpha chain, IL-2RA (CD25). STAT5 was found to induce expression of CD25 in Lin-/Sca-1+/Kit+ stem cells in C57Bl/6 mice. Correspondingly, shRNA-induced STAT5-depletion resulted in decreased CD25 expression in KU812 cells. Moreover, the BCR/ABL1 inhibitors nilotinib and ponatinib were found to decrease STAT5 activity and CD25 expression in KU812 cells and primary CML LSCs. A CD25-targeting shRNA was found to augment proliferation of KU812 cells in vitro and their engraftment in vivo in NOD/SCID-IL-2Rγ-/- mice. In drug-screening experiments, the PI3-Kinase/mTOR blocker BEZ235 promoted the expression of STAT5 and CD25 in CML cells. Finally, we found that BEZ235 produces synergistic anti-neoplastic effects on CML cells when applied in combination with nilotinib or ponatinib. CONCLUSION CD25 is a novel STAT5-dependent marker of CML LSCs and may be useful for LSC detection and LSC isolation in clinical practice and basic science. Moreover, CD25 serves as a growth-regulator of CML LSCs, which may have biological and clinical implications and may pave the way for the development of new more effective LSC-eradicating treatment strategies in CML.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Holyoake, Professor Tessa
• Authors: Sadovnik, I., Hoelbl-Kovacic, A., Herrmann, H., Eisenwort, G., Cerny-Reiterer, S., Warsch, W., Hoermann, G., Greiner, G., Blatt, K., Peter, B., Stefanzl, G., Berger, D., Bilban, M., Herndlhofer, S., Sill, H., Sperr, W. R., Streubel, B., Mannhalter, C., Holyoake, T. L., Sexl, V., and Valent, P.
• College/School: College of Medical Veterinary and Life Sciences > School of Cancer Sciences
• Journal Name: Clinical Cancer Research
• Publisher: American Association for Cancer Research
• ISSN: 1078-0432
• ISSN (Online): 1557-3265
• Published Online: 25 November 2015
• Copyright Holders: Copyright © 2015 American Association for Cancer Research
• First Published: First published in Clinical Cancer Research 22(8):2051-2061
• Publisher Policy: Reproduced in accordance with the copyright policy of the publisher