Telomestatin impairs glioma stem cell survival and growth through the disruption of telomeric G-quadruplex and inhibition of the proto-oncogene, c-Myb.
OBJECTIVE
Glioma stem cells (GSC) are a critical therapeutic target of glioblastoma multiforme (GBM).


METHODS
The effects of a G-quadruplex ligand, telomestatin, were evaluated using patient-derived GSCs, non-stem tumor cells (non-GSC), and normal fetal neural precursors in vitro and in vivo. The molecular targets of telomestatin were determined by immunofluorescence in situ hybridization (iFISH) and cDNA microarray. The data were then validated by in vitro and in vivo functional assays, as well as by immunohistochemistry against 90 clinical samples.


RESULTS
Telomestatin impaired the maintenance of GSC stem cell state by inducing apoptosis in vitro and in vivo. The migration potential of GSCs was also impaired by telomestatin treatment. In contrast, both normal neural precursors and non-GSCs were relatively resistant to telomestatin. Treatment of GSC-derived mouse intracranial tumors reduced tumor sizes in vivo without a noticeable cell death in normal brains. iFISH revealed both telomeric and non-telomeric DNA damage by telomestatin in GSCs but not in non-GSCs. cDNA microarray identified a proto-oncogene, c-Myb, as a novel molecular target of telomestatin in GSCs, and pharmacodynamic analysis in telomestatin-treated tumor-bearing mouse brains showed a reduction of c-Myb in tumors in vivo. Knockdown of c-Myb phenocopied telomestatin-treated GSCs both in vitro and in vivo, and restoring c-Myb by overexpression partially rescued the phenotype. Finally, c-Myb expression was markedly elevated in surgical specimens of GBMs compared with normal tissues.


CONCLUSIONS
These data indicate that telomestatin potently eradicates GSCs through telomere disruption and c-Myb inhibition, and this study suggests a novel GSC-directed therapeutic strategy for GBMs.
Department of Neurological Surgery, Dardinger, Center for Neuro-oncology, James Cancer Hospital and The Ohio State University, Columbus, Ohio 43210, USA.
Takeshi
T
Miyazaki
Yang
Y
Pan
Kaushal
K
Joshi
Deepti
D
Purohit
Bin
B
Hu
Habibe
H
Demir
Sarmistha
S
Mazumder
Sachiko
S
Okabe
Takao
T
Yamori
Mariano
M
Viapiano
Kazuo
K
Shin-ya
Hiroyuki
H
Seimiya
Ichiro
I
Nakano
D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000494:pharmacology*; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics; D004249:DNA Damage / Q000187:drug effects; D054856:G-Quadruplexes / Q000187:drug effects*; D015870:Gene Expression; D020570:Genes, myb / Q000187:drug effects*; D005910:Glioma / Q000188:drug therapy / Q000235:genetics*; D006801:Humans; D051379:Mice; D014411:Neoplastic Stem Cells / Q000187:drug effects* / Q000378:metabolism*; D058953:Neural Stem Cells / Q000187:drug effects; D010080:Oxazoles / Q000008:administration & dosage / Q000494:pharmacology*; D000090063:Proto-Oncogene Mas; D023041:Xenograft Model Antitumor Assays
D000970:Antineoplastic Agents; C000715470:MAS1 protein, human; D010080:Oxazoles; D000090063:Proto-Oncogene Mas; C431888:telomestatin