Effects of soluble CPE on glioma cell migration are associated with mTOR activation and enhanced glucose flux

Elena I Ilina, Angela Armento, Leticia Garea Sanchez, Marina Reichlmeir, Yannick Braun, Cornelia Penski, David Capper, Felix Sahm, Lukas Jennewein, Patrick N Harter, Sven Zukunft, Ingrid Fleming, Dorothea Schulte, Francois Le Guerroué, Christian Behrends, Michael W Ronellenfitsch, Ulrike Naumann, Michel Mittelbronn

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Carboxypeptidase E (CPE) has recently been described as a multifunctional protein that regulates proliferation, migration and survival in several tumor entities. In glioblastoma (GBM), the most malignant primary brain tumor, secreted CPE (sCPE) was shown to modulate tumor cell migration. In our current study, we aimed at clarifying the underlying molecular mechanisms regulating anti-migratory as well as novel metabolic effects of sCPE in GBM. Here we show that sCPE activates mTORC1 signaling in glioma cells detectable by phosphorylation of its downstream target RPS6. Additionally, sCPE diminishes glioma cell migration associated with a negative regulation of Rac1 signaling via RPS6, since both inhibition of mTOR and stimulation of Rac1 results in a reversed effect of sCPE on migration. Knockdown of CPE leads to a decrease of active RPS6 associated with increased GBM cell motility. Apart from this, we show that sCPE enhances glucose flux into the tricarboxylic acid cycle at the expense of lactate production, thereby decreasing aerobic glycolysis, which might as well contribute to a less invasive behavior of tumor cells. Our data contributes to a better understanding of the complexity of GBM cell migration and sheds new light on how tumor cell invasion and metabolic plasticity are interconnected.

Original languageEnglish
Pages (from-to)67567-67591
Number of pages25
JournalOncotarget
Volume8
Issue number40
DOIs
Publication statusPublished - 15 Sep 2017

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