Roles of mTOR and STAT3 in autophagy induced by telomere 3' overhang-specific DNA oligonucleotides

Autophagy. 2007 Sep-Oct;3(5):496-8. doi: 10.4161/auto.4602. Epub 2007 Jun 20.

Abstract

Telomere 3' overhang-specific DNA oligonucleotides (T-oligos) induce cancer cell death, presumably by mimicking telomere loop disruption and are, therefore, considered a promising new therapeutic strategy. We previously demonstrated that T-oligos inhibit the proliferation of malignant glioma cells in vitro and in vivo by inducing non-apoptotic autophagy. Using a reverse-phase protein microarray analysis and Western blotting, we revealed that T-oligos inhibit the mammalian target of rapamycin (mTOR) and the signal transducer and activator of transcription 3 (STAT3). Moreover, rapamycin (mTOR inhibitor) and AG490 (STAT3 inhibitor) sensitize malignant glioma cells to T-oligos by augmenting autophagy. Although mTOR is well known as a negative regulator of autophagy, the relationship between STAT3 and autophagy has never been demonstrated, to our knowledge. These findings suggest that, by exhibiting a novel mechanism of inducing autophagy through inhibition of mTOR and STAT3, T-oligos are a promising therapeutic agent for treating malignant gliomas. Here, we discuss evidence for T-oligos' effects on cell signaling pathways that may explain their ability to stimulate autophagy by inhibiting STAT3 as well as mTOR.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Autophagy / drug effects
  • Autophagy / genetics
  • Autophagy / physiology*
  • Cell Line, Tumor
  • Glioma / drug therapy
  • Glioma / genetics
  • Glioma / pathology
  • Glioma / physiopathology
  • Humans
  • Mice
  • Models, Biological
  • Oligodeoxyribonucleotides / genetics
  • Oligodeoxyribonucleotides / pharmacology*
  • Protein Kinases / physiology*
  • STAT3 Transcription Factor / antagonists & inhibitors
  • STAT3 Transcription Factor / physiology*
  • Sirolimus / pharmacology
  • TOR Serine-Threonine Kinases
  • Tyrphostins / pharmacology

Substances

  • Oligodeoxyribonucleotides
  • STAT3 Transcription Factor
  • STAT3 protein, human
  • Tyrphostins
  • alpha-cyano-(3,4-dihydroxy)-N-benzylcinnamide
  • Protein Kinases
  • MTOR protein, human
  • mTOR protein, mouse
  • TOR Serine-Threonine Kinases
  • Sirolimus