Hedgehog/GLI1 regulates IGF dependent malignant behaviors in glioma stem cells
Article first published online: 25 JAN 2011
Copyright © 2010 Wiley-Liss, Inc.
Journal of Cellular Physiology
Volume 226, Issue 4, pages 1118–1127, April 2011
How to Cite
Hsieh, A., Ellsworth, R. and Hsieh, D. (2011), Hedgehog/GLI1 regulates IGF dependent malignant behaviors in glioma stem cells. J. Cell. Physiol., 226: 1118–1127. doi: 10.1002/jcp.22433
- Issue published online: 25 JAN 2011
- Article first published online: 25 JAN 2011
- Accepted manuscript online: 20 SEP 2010 12:00AM EST
- Manuscript Accepted: 7 SEP 2010
- Manuscript Received: 10 MAR 2010
A population of tumorigenic, chemoresistant, and radioresistant cancer stem cells is postulated to contribute to the aggressive and fatal clinical course of glioblastomas. Activation of the Hedgehog (HH) pathway and increased expression of its downstream effector GLI1 are driving factors of glioma tumorigenicity and glioma stem cell (GSC) biology. In this study, we describe a dependence of insulin-like growth factor (IGF) signaling on active HH/GLI1 in GSCs. Insulin receptor substrate 1 (IRS1) was identified as a target of the GLI1 transcription factor and inhibition of GLI1 was sufficient to obstruct IRS1 protein expression and IGF-I induced mitogen-activated protein kinase (MAPK) activation. Suppression of GLI1 activity decreased the responsiveness of GSCs to IGF-I stimulation and constrained IGF-I dependent GSC proliferation, clonogenicity, invasion, and angiogenesis. In addition, blockade of the HH/GLI1 and IGF pathways countered the intrinsic and acquired resistance of GSCs to temozolomide. These results provide further insight into the oncogenic mechanisms of the HH pathway in glioblastoma and demonstrate a cooperative signaling axis between the HH/GLI1 and IGF pathways to propagate malignant GSC phenotypes. J. Cell. Physiol. 226: 1118–1127, 2011. © 2010 Wiley-Liss, Inc.