Regulation of glioblastoma stem cells by retinoic acid: role for Notch pathway inhibition

• Published in: Oncogene Vol. 30; no. 31; pp. 3454 - 3467
• Main Authors: Ying, M, Wang, S, Sang, Y, Sun, P, Lal, B, Goodwin, C R, Guerrero-Cazares, H, Quinones-Hinojosa, A, Laterra, J, Xia, S
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 04.08.2011; Nature Publishing Group
• Subjects: 631/67/71; 631/80/86; 692/699/67/1059/99; 692/699/67/1922; AC133 Antigen; Animals; Antigens, CD - biosynthesis; Antineoplastic Agents - pharmacology; Antineoplastic Agents - therapeutic use; Apoptosis; Biological and medical sciences; Brain cancer; Brain Neoplasms - genetics; Brain Neoplasms - pathology; Care and treatment; Cell adhesion; Cell Biology; Cell differentiation; Cell Differentiation - drug effects; Cell Line, Tumor; Cell physiology; Cell transformation and carcinogenesis. Action of oncogenes and antioncogenes; Cellular biology; Cyclin D1; Cyclin D1 - biosynthesis; Cytoskeleton; Diagnosis; Female; Fundamental and applied biological sciences. Psychology; Gene expression; Gene Expression Profiling; Gene Expression Regulation, Neoplastic - drug effects; Glial fibrillary acidic protein; Glial Fibrillary Acidic Protein - biosynthesis; Glioblastoma; Glioblastoma - genetics; Glioblastoma - pathology; Glioblastoma multiforme; Glycoproteins - biosynthesis; Health aspects; Human Genetics; Humans; Immunofluorescence; Intermediate Filament Proteins - biosynthesis; Internal Medicine; Intracellular signalling; Medical sciences; Medicine; Medicine & Public Health; Mice; Mice, Nude; Molecular and cellular biology; Neoplastic Stem Cells - drug effects; Neoplastic Stem Cells - metabolism; Nerve Tissue Proteins - biosynthesis; Nestin; Neural stem cells; Neurology; Neurospheres; Oncology; original-article; Peptides; Proliferating Cell Nuclear Antigen - biosynthesis; Receptors, Notch - antagonists & inhibitors; Retinoic acid; RNA-Binding Proteins - biosynthesis; Serum-free medium; Signal transduction; SOXB1 Transcription Factors - biosynthesis; Stem cells; Tretinoin; Tretinoin - pharmacology; Tretinoin - therapeutic use; Tubulin - biosynthesis; Tumors; Tumors of the nervous system. Phacomatoses; Xenografts; United States; retinoic acid; glioblastoma; differentiation; cancer stem cell; Notch; Nervous system diseases; Stem cell; Retinoid; Glioblastoma; Malignant tumor; Carcinogenesis; Cell signaling; Malignant glioma; Regulation(control); Central nervous system disease; Inhibition; Differentiation; Retinoic acid; Cancer
• ISSN: 0950-9232; 1476-5594
• DOI: 10.1038/onc.2011.58

It is necessary to understand mechanisms by which differentiating agents influence tumor-initiating cancer stem cells. Toward this end, we investigated the cellular and molecular responses of glioblastoma stem-like cells (GBM-SCs) to all- trans retinoic acid (RA). GBM-SCs were grown as non-adherent neurospheres in growth factor supplemented serum-free medium. RA treatment rapidly induced morphology changes, induced growth arrest at G1/G0 to S transition, decreased cyclin D1 expression and increased p27 expression. Immunofluorescence and western blot analysis indicated that RA induced the expression of lineage-specific differentiation markers Tuj1 and GFAP and reduced the expression of neural stem cell markers such as CD133, Msi-1, nestin and Sox-2. RA treatment dramatically decreased neurosphere-forming capacity, inhibited the ability of neurospheres to form colonies in soft agar and inhibited their capacity to propagate subcutaneous and intracranial xenografts. Expression microarray analysis identified ∼350 genes that were altered within 48 h of RA treatment. Affected pathways included retinoid signaling and metabolism, cell-cycle regulation, lineage determination, cell adhesion, cell–matrix interaction and cytoskeleton remodeling. Notch signaling was the most prominent of these RA-responsive pathways. Notch pathway downregulation was confirmed based on the downregulation of HES and HEY family members. Constitutive activation of Notch signaling with the Notch intracellular domain rescued GBM neurospheres from the RA-induced differentiation and stem cell depletion. Our findings identify mechanisms by which RA targets GBM-derived stem-like tumor-initiating cells and novel targets applicable to differentiation therapies for glioblastoma.