Abstract
Radiotherapy represents the most effective nonsurgical treatments for gliomas. However, gliomas are highly radioresistant and recurrence is nearly universal. Results from our laboratory and other groups suggest that cancer stem cells contribute to radioresistance in gliomas and breast cancers. The Notch pathway is critically implicated in stem cell fate determination and cancer. In this study, we show that inhibition of Notch pathway with gamma-secretase inhibitors (GSIs) renders the glioma stem cells more sensitive to radiation at clinically relevant doses. GSIs enhance radiation-induced cell death and impair clonogenic survival of glioma stem cells but not non-stem glioma cells. Expression of the constitutively active intracellular domains of Notch1 or Notch2 protect glioma stem cells against radiation. Notch inhibition with GSIs does not alter the DNA damage response of glioma stem cells after radiation but rather reduces Akt activity and Mcl-1 levels. Finally, knockdown of Notch1 or Notch2 sensitizes glioma stem cells to radiation and impairs xenograft tumor formation. Taken together, our results suggest a critical role of Notch signaling to regulate radioresistance of glioma stem cells. Inhibition of Notch signaling holds promise to improve the efficiency of current radiotherapy in glioma treatment.
Publication types
-
Research Support, N.I.H., Extramural
-
Research Support, Non-U.S. Gov't
MeSH terms
-
AC133 Antigen
-
Amyloid Precursor Protein Secretases / antagonists & inhibitors
-
Amyloid Precursor Protein Secretases / metabolism
-
Animals
-
Antigens, CD / metabolism
-
Cell Death
-
Cell Proliferation
-
Cell Survival
-
Dose-Response Relationship, Radiation
-
Enzyme Inhibitors / pharmacology
-
Glioblastoma / drug therapy
-
Glioblastoma / metabolism
-
Glioblastoma / pathology
-
Glioblastoma / radiotherapy*
-
Glycoproteins / metabolism
-
Humans
-
Mice
-
Mice, Nude
-
Myeloid Cell Leukemia Sequence 1 Protein
-
Neoplastic Stem Cells / drug effects
-
Neoplastic Stem Cells / metabolism
-
Neoplastic Stem Cells / pathology
-
Neoplastic Stem Cells / radiation effects*
-
Peptides / metabolism
-
Phosphatidylinositol 3-Kinases / metabolism
-
Proto-Oncogene Proteins c-akt / metabolism
-
Proto-Oncogene Proteins c-bcl-2 / metabolism
-
RNA Interference
-
Radiation Tolerance* / drug effects
-
Radiation-Sensitizing Agents / pharmacology
-
Receptor, Notch1 / genetics
-
Receptor, Notch1 / metabolism*
-
Receptor, Notch2 / genetics
-
Receptor, Notch2 / metabolism*
-
Signal Transduction / radiation effects
-
Spheroids, Cellular
-
Time Factors
-
Transfection
-
Tumor Burden
-
Tumor Cells, Cultured
-
Xenograft Model Antitumor Assays
Substances
-
AC133 Antigen
-
Antigens, CD
-
Enzyme Inhibitors
-
Glycoproteins
-
Mcl1 protein, mouse
-
Myeloid Cell Leukemia Sequence 1 Protein
-
Peptides
-
Proto-Oncogene Proteins c-bcl-2
-
Radiation-Sensitizing Agents
-
Receptor, Notch1
-
Receptor, Notch2
-
Phosphatidylinositol 3-Kinases
-
Proto-Oncogene Proteins c-akt
-
Amyloid Precursor Protein Secretases