Regulation of hypoxia-induced autophagy in glioblastoma involves ATG9A

Siti Aminah Abdul Rahim, Anne Dirkse, Anais Oudin, Anne Schuster, Jill Bohler, Vanessa Barthelemy, Arnaud Muller, Laurent Vallar, Bassam Janji, Anna Golebiewska, Simone P. Niclou*

*Corresponding author for this work

Research output: Contribution to journalArticleResearchpeer-review

65 Citations (Scopus)

Abstract

Background: Hypoxia is negatively associated with glioblastoma (GBM) patient survival and contributes to tumour resistance. Anti-angiogenic therapy in GBM further increases hypoxia and activates survival pathways. The aim of this study was to determine the role of hypoxia-induced autophagy in GBM.Methods: Pharmacological inhibition of autophagy was applied in combination with bevacizumab in GBM patient-derived xenografts (PDXs). Sensitivity towards inhibitors was further tested in vitro under normoxia and hypoxia, followed by transcriptomic analysis. Genetic interference was done using ATG9A-depleted cells.Results: We find that GBM cells activate autophagy as a survival mechanism to hypoxia, although basic autophagy appears active under normoxic conditions. Although single agent chloroquine treatment in vivo significantly increased survival of PDXs, the combination with bevacizumab resulted in a synergistic effect at low non-effective chloroquine dose. ATG9A was consistently induced by hypoxia, and silencing of ATG9A led to decreased proliferation in vitro and delayed tumour growth in vivo. Hypoxia-induced activation of autophagy was compromised upon ATG9A depletion.Conclusions: This work shows that inhibition of autophagy is a promising strategy against GBM and identifies ATG9 as a novel target in hypoxia-induced autophagy. Combination with hypoxia-inducing agents may provide benefit by allowing to decrease the effective dose of autophagy inhibitors.

Original languageEnglish
Pages (from-to)813-825
Number of pages13
JournalBritish Journal of Cancer
Volume117
Issue number6
DOIs
Publication statusPublished - 5 Sep 2017

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