Abstract | BACKGROUND: METHODS: Primary neonatal mouse astrocyte cultures were employed to determine the consequence of phosphatidylinositol-3 kinase (PI3K)/Akt and MEK inhibition on Nf1-deficient astrocyte growth. Nf1 optic glioma-bearing mice were used to assess the effect of Akt and MEK inhibition on tumor volume, proliferation, and retinal ganglion cell dysfunction. RESULTS: Both MEK and Akt were hyperactivated in Nf1-deficient astrocytes in vitro and in Nf1 murine optic gliomas in vivo. Pharmacologic PI3K or Akt inhibition reduced Nf1-deficient astrocyte proliferation to wild-type levels, while PI3K inhibition decreased Nf1 optic glioma volume and proliferation. Akt inhibition of Nf1-deficient astrocyte and optic glioma growth reflected Akt-dependent activation of mammalian target of rapamycin (mTOR). Sustained MEK pharmacologic blockade also attenuated Nf1-deficient astrocytes as well as Nf1 optic glioma volume and proliferation. Importantly, these MEK inhibitory effects resulted from p90RSK-mediated, Akt-independent mTOR activation. Finally, both PI3K and MEK inhibition reduced optic glioma-associated retinal ganglion cell loss and nerve fiber layer thinning. CONCLUSION: These findings establish that the convergence of 2 distinct Ras effector pathways on mTOR signaling maintains Nf1 mouse optic glioma growth, supporting the evaluation of pharmacologic inhibitors that target mTOR function in future human NF1-optic pathway glioma clinical trials.
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Authors | Aparna Kaul, Joseph A Toonen, Patrick J Cimino, Scott M Gianino, David H Gutmann |
Journal | Neuro-oncology
(Neuro Oncol)
Vol. 17
Issue 6
Pg. 843-53
(Jun 2015)
ISSN: 1523-5866 [Electronic] England |
PMID | 25534823
(Publication Type: Journal Article, Research Support, N.I.H., Extramural)
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Copyright | © The Author(s) 2014. Published by Oxford University Press on behalf of the Society for Neuro-Oncology. All rights reserved. For permissions, please e-mail: [email protected]. |
Chemical References |
- Neurofibromin 1
- MTOR protein, human
- Proto-Oncogene Proteins c-akt
- TOR Serine-Threonine Kinases
- MAP Kinase Kinase 1
- MAP2K1 protein, human
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Topics |
- Animals
- Astrocytes
(metabolism)
- Brain Neoplasms
(metabolism)
- Cell Proliferation
- Humans
- MAP Kinase Kinase 1
(metabolism)
- MAP Kinase Signaling System
- Mice
- Mice, Inbred C57BL
- Neurofibromatosis 1
(metabolism)
- Neurofibromin 1
(genetics, metabolism)
- Optic Nerve Glioma
(metabolism)
- Phosphatidylinositol 3-Kinases
(metabolism)
- Proto-Oncogene Proteins c-akt
(metabolism)
- TOR Serine-Threonine Kinases
(antagonists & inhibitors, metabolism)
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