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Glutamine deprivation stimulates mTOR-JNK-dependent chemokine secretion.

ABSTRACT: The non-essential amino acid, glutamine, exerts pleiotropic effects on cell metabolism, signalling and stress resistance. Here we demonstrate that short-term glutamine restriction triggers an endoplasmic reticulum (ER) stress response that leads to production of the pro-inflammatory chemokine, interleukin-8 (IL-8). Glutamine deprivation-induced ER stress triggers colocalization of autophagosomes, lysosomes and the Golgi into a subcellular structure whose integrity is essential for IL-8 secretion. The stimulatory effect of glutamine restriction on IL-8 production is attributable to depletion of tricarboxylic acid cycle intermediates. The protein kinase, mTOR, is also colocalized with the lysosomal membrane clusters induced by glutamine deprivation, and inhibition of mTORC1 activity abolishes both endomembrane reorganization and IL-8 secretion. Activated mTORC1 elicits IL8 gene expression via the activation of an IRE1-JNK signalling cascade. Treatment of cells with a glutaminase inhibitor phenocopies glutamine restriction, suggesting that these results will be relevant to the clinical development of glutamine metabolism inhibitors as anticancer agents.

SUBMITTER: Shanware NP

PROVIDER: S-EPMC4200525 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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Glutamine deprivation stimulates mTOR-JNK-dependent chemokine secretion.

Shanware Naval P NP Bray Kevin K Eng Christina H CH Wang Fang F Follettie Maximillian M Myers Jeremy J Fantin Valeria R VR Abraham Robert T RT

Nature communications 20140925

The non-essential amino acid, glutamine, exerts pleiotropic effects on cell metabolism, signalling and stress resistance. Here we demonstrate that short-term glutamine restriction triggers an endoplasmic reticulum (ER) stress response that leads to production of the pro-inflammatory chemokine, interleukin-8 (IL-8). Glutamine deprivation-induced ER stress triggers colocalization of autophagosomes, lysosomes and the Golgi into a subcellular structure whose integrity is essential for IL-8 secretion ...[more]

PMID: 25254627

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Project description:BackgroundReprogrammed energy metabolism has become an emerging hallmark of cancer in recent years. Transporters have been reported to be amino acid sensors involved in controlling mTOR recruitment and activation, which is crucial for the growth of both normal and tumor cells. L-type amino acid transporter 2 (LAT2), encoded by the SLC7A8 gene, is a Na+-independent neutral amino acid transporter and is responsible for transporting neutral amino acids, including glutamine, which can activate mTOR. Previous studies have shown that LAT2 was overexpressed in gemcitabine-resistant pancreatic cancer cells. However, the role of LAT2 in chemoresistance in pancreatic cancer remains uncertain and elusive.MethodsThe effects of LAT2 on biological behaviors were analyzed. LAT2 and LDHB levels in tissues were detected, and the clinical value was evaluated.ResultsWe demonstrated that LAT2 emerged as an oncogenic protein and could decrease the gemcitabine sensitivity of pancreatic cancer cells in vitro and in vivo. The results of a survival analysis indicated that high expression levels of both LAT2 and LDHB predicted a poor prognosis in patients with pancreatic cancer. Furthermore, we found that LAT2 could promote proliferation, inhibit apoptosis, activate glycolysis and alter glutamine metabolism to activate mTOR in vitro and in vivo. Next, we found that gemcitabine combined with an mTOR inhibitor (RAD001) could reverse the decrease in chemosensitivity caused by LAT2 overexpression in pancreatic cancer cells. Mechanistically, we demonstrated that LAT2 could regulate two glutamine-dependent positive feedback loops (the LAT2/p-mTORSer2448 loop and the glutamine/p-mTORSer2448/glutamine synthetase loop) to promote glycolysis and decrease gemcitabine (GEM) sensitivity in pancreatic cancer.ConclusionTaken together, our data reveal that LAT2 functions as an oncogenic protein and could regulate glutamine-dependent mTOR activation to promote glycolysis and decrease GEM sensitivity in pancreatic cancer. The LAT2-mTOR-LDHB pathway might be a promising therapeutic target in pancreatic cancer.

Dataset Information

Glutamine deprivation stimulates mTOR-JNK-dependent chemokine secretion.

Publications

Glutamine deprivation stimulates mTOR-JNK-dependent chemokine secretion.

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