title: G-quadruplex ligand-induced DNA damage response coupled with telomere dysfunction and replication stress in glioma stem cells.
abstract: Glioblastoma (GBM) is an invariably fatal brain tumor in which a small subpopulation of self-renewable glioma stem cells (GSCs) contributes to tumor propagation and relapse. Targeting GSCs could therefore have a significant clinical impact for GBM. Telomestatin is a naturally-occurring compound that preferentially impairs GSC growth by perturbing transcription and inducing a DNA damage response. Telomestatin stabilizes G-quadruplexes (G4s), which are guanine-rich four-strand nucleic acid structures observed in vitro and in vivo. However, the mechanism underlying the GSC-selective nature of the DNA damage response remains unknown. Here we demonstrate that GSCs are more susceptible to telomestatin-induced telomere dysfunction and replication stress when compared with GSC-derived non-stem glioma cells (NSGCs). Telomestatin induced dissociation of the telomere-capping protein TRF2 from telomeres, leading to telomeric DNA damage in GSCs-but not in NSGCs. BIBR1532, a telomerase catalytic inhibitor, did not preferentially inhibit GSC growth, suggesting that telomestatin promotes telomere dysfunction in a telomerase-independent manner. GSCs and NSGCs had comparable levels of G4s in their nuclei, and both responded to telomestatin with phosphorylation of RPA2 at Ser33-a hallmark of replication stress. However, activation of the checkpoint kinase Chk1, induction of a DNA damage response, and subsequent growth inhibition occurred only in telomestatin-treated GSCs. These observations suggest that telomestatin impairs GSC growth through removal of TRF2 from telomeres and potent activation of the replication stress response pathway. Therefore, a novel G4-directed therapeutic strategy could specifically target cancer stem cells in GBM.
authors: Division of Molecular Biotherapy, Cancer Chemotherapy Center, Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koto-ku, Tokyo 135-8550, Japan; Laboratory of Molecular Target Therapy of Cancer, Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, 3-8-31 Ariake, Koto-ku, Tokyo 135-8550, Japan.
authors: Daiki
authors: D
authors: Hasegawa
authors: Division of Molecular Biotherapy, Cancer Chemotherapy Center, Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koto-ku, Tokyo 135-8550, Japan.
authors: Sachiko
authors: S
authors: Okabe
authors: Division of Molecular Biotherapy, Cancer Chemotherapy Center, Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koto-ku, Tokyo 135-8550, Japan.
authors: Keiji
authors: K
authors: Okamoto
authors: Department of Neurosurgery, Comprehensive Cancer Center, University of Alabama at Birmingham, 1824 6th Avenue South, Birmingham, AL 35233, USA.
authors: Ichiro
authors: I
authors: Nakano
authors: Biomedical Information Research Center, National Institute of Advanced Industrial Science and Technology, 2-4-7 Aomi, Koto-ku, Tokyo 135-0064, Japan.
authors: Kazuo
authors: K
authors: Shin-ya
authors: Division of Molecular Biotherapy, Cancer Chemotherapy Center, Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koto-ku, Tokyo 135-8550, Japan; Laboratory of Molecular Target Therapy of Cancer, Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, 3-8-31 Ariake, Koto-ku, Tokyo 135-8550, Japan. Electronic address: hseimiya@jfcr.or.jp.
authors: Hiroyuki
authors: H
authors: Seimiya
mesh_terms: D045744:Cell Line, Tumor; D004249:DNA Damage; D004261:DNA Replication / Q000235:genetics*; D054856:G-Quadruplexes; D005909:Glioblastoma / Q000235:genetics*; D006801:Humans; D014411:Neoplastic Stem Cells / Q000502:physiology*; D016615:Telomere / Q000235:genetics*; D059505:Telomere Homeostasis / Q000235:genetics
keywords: DNA damage response; G-quadruplex; Glioma stem cells; Replication stress; Telomere