It has been proposed that rare, treatment-resistant neoplastic stem cells are critical for long-term tumor growth. Normal stem cells require signals from a stromal "niche" to self-renew. However, the role of such niche-signals in regulating cancer stem cells (CSCs) is largely unknown. The Notch signaling pathway regulates neural stem cell self-renewal, and recent studies found that CSCs in glioblastoma (GBM) have elevated Notch activity. Our recent data shows that Notch pathway inhibition by gamma-secretase inhibitors reduced CD133 expression and reduces glioblastoma neurosphere propagation both in vitro and in vivo. In the current application, we propose using GBM neurosphere cultures to determine the mechanism and niche-dependence of Notch activation in CSCs. Specifically, we will seek to determine if Notch activation is driven by juxtacrine signaling between tumor cells replicating the classical process of lateral inhibition, by stromal niche signals, or both.
Aim1 - Determine if activation of Notch in CSCs is mediated by juxtacrine signaling via Notch ligands expressed in better-differentiated tumor cells.
Aim2 - Define if the endothelial cells function as CSC niche by providing Notch ligands to CSCs in glioblastoma.
Aim3 - Determine if regulation of Notch activity in endothelial cells contributes to the non-functional microvascular proliferation in GBM. Answering these questions will facilitate the development of novel therapies and enhance our understanding of cancer stem cell biology.

Public Health Relevance

Glioblastoma is the most malignant brain tumor in adult with no successful treatment during the past thirty years. The goal of this proposal is to understand how an important tumor micro-environment (cancer stem cell niche) regulates glioblastoma initiating cells in order to develop a novel therapeutic strategy for this deadly disease.

Agency
National Institute of Health (NIH)
Type
Research Project (R01)
Project #
5R01CA148621-04
Application #
8685180
Study Section
Cancer Molecular Pathobiology Study Section (CAMP)
Program Officer
Woodhouse, Elizabeth
Project Start
Project End
Budget Start
Budget End
Support Year
4
Fiscal Year
2014
Total Cost
Indirect Cost
Name
University of Michigan Ann Arbor
Department
Neurosurgery
Type
Schools of Medicine
DUNS #
City
Ann Arbor
State
MI
Country
United States
Zip Code
48109
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