NOTCH Pathway Blockade Depletes CD133‐Positive Glioblastoma Cells and Inhibits Growth of Tumor Neurospheres and Xenografts

• Published in: Stem cells (Dayton, Ohio) Ohio), 2010-01, Vol.28 (1), p.5-16
• Main Authors: Fan, Xing, Khaki, Leila, Zhu, Thant S., Soules, Mary E., Talsma, Caroline E., Gul, Naheed, Koh, Cheryl, Zhang, Jiangyang, Li, Yue‐Ming, Maciaczyk, Jarek, Nikkhah, Guido, DiMeco, Francesco, Piccirillo, Sara, Vescovi, Angelo L., Eberhart, Charles G.
• Format: Article
• Language: English
• Subjects: AC133 Antigen; Amyloid Precursor Protein Secretases - antagonists & inhibitors; Amyloid Precursor Protein Secretases - metabolism; Animals; Antigens, CD - metabolism; Antineoplastic Agents - pharmacology; Apoptosis - drug effects; Biomarkers, Tumor - metabolism; Brain Neoplasms - drug therapy; Brain Neoplasms - enzymology; Brain Neoplasms - immunology; Brain Neoplasms - pathology; Cancer Stem Cell; Cell Proliferation - drug effects; Dose-Response Relationship, Drug; Enzyme Inhibitors - pharmacology; Female; Glioblastoma; Glioblastoma - drug therapy; Glioblastoma - enzymology; Glioblastoma - immunology; Glioblastoma - pathology; Glycoproteins - metabolism; Humans; Mice; Mice, Nude; Neoplastic Stem Cells - drug effects; Neoplastic Stem Cells - enzymology; Neoplastic Stem Cells - immunology; Neoplastic Stem Cells - pathology; Neurons - drug effects; Neurons - enzymology; Neurons - immunology; Neurons - pathology; NOTCH; Peptides - metabolism; Phosphorylation; Proto-Oncogene Proteins c-akt - metabolism; Receptor, Notch2 - genetics; Receptor, Notch2 - metabolism; Signal Transduction - drug effects; Spheroids, Cellular; STAT3 Transcription Factor - metabolism; Time Factors; Transfection; Tumor Burden; Tumor Cells, Cultured; Xenograft Model Antitumor Assays; γ‐Secretase inhibitor
• ISSN: 1066-5099; 1549-4918
• DOI: 10.1002/stem.254

Cancer stem cells (CSCs) are thought to be critical for the engraftment and long‐term growth of many tumors, including glioblastoma (GBM). The cells are at least partially spared by traditional chemotherapies and radiation therapies, and finding new treatments that can target CSCs may be critical for improving patient survival. It has been shown that the NOTCH signaling pathway regulates normal stem cells in the brain, and that GBMs contain stem‐like cells with higher NOTCH activity. We therefore used low‐passage and established GBM‐derived neurosphere cultures to examine the overall requirement for NOTCH activity, and also examined the effects on tumor cells expressing stem cell markers. NOTCH blockade by γ‐secretase inhibitors (GSIs) reduced neurosphere growth and clonogenicity in vitro, whereas expression of an active form of NOTCH2 increased tumor growth. The putative CSC markers CD133, NESTIN, BMI1, and OLIG2 were reduced following NOTCH blockade. When equal numbers of viable cells pretreated with either vehicle (dimethyl sulfoxide) or GSI were injected subcutaneously into nude mice, the former always formed tumors, whereas the latter did not. In vivo delivery of GSI by implantation of drug‐impregnated polymer beads also effectively blocked tumor growth, and significantly prolonged survival, albeit in a relatively small cohort of animals. We found that NOTCH pathway inhibition appears to deplete stem‐like cancer cells through reduced proliferation and increased apoptosis associated with decreased AKT and STAT3 phosphorylation. In summary, we demonstrate that NOTCH pathway blockade depletes stem‐like cells in GBMs, suggesting that GSIs may be useful as chemotherapeutic reagents to target CSCs in malignant gliomas. STEM CELLS 2010;28:5–16