Elsevier

Neoplasia

Volume 12, Issue 8, August 2010, Pages 659-667, IN4-IN6
Neoplasia

Glutamate Receptor GRIA3—Target of CUX1 and Mediator of Tumor Progression in Pancreatic Cancer1,2

https://doi.org/10.1593/neo.10486Get rights and content
Under a Creative Commons license
open access

Previously, we identified the transcription factor CUX1 as an important modulator of invasion and resistance to apoptosis. Expression profiles suggested that CUX1 regulates a complex transcriptional program mediating tumor progression. We aimed to identify functionally relevant targets of CUX1 by using RNA interference (RNAi)-based loss-of-function screens. Therefore, we generated an RNAi library containing putative transcriptional targets of CUX1 identified by microarrays and performed cell viability screens. Using this approach, several CUX1 targets with effect on tumor cell viability were identified, including the glutamate receptor GRIA3, which was validated in detail for its effects on proliferation, apoptosis, and cell migration using RNAi knock-down and overexpression strategies in vitro, as well as xenograft models in vivo. The expression of GRIA3 was evaluated in human pancreatic cancer tissues. We found that knock-down of GRIA3 significantly reduced proliferation and migration and enhanced apoptosis. In contrast, overexpression of GRIA3 significantly reduced apoptosis and enhanced both proliferation and tumor cell migration. GRIA3 could be confirmed as a downstream effector of CUX1 and was expressed in pancreatic cancer tissues. In vivo, GRIA3 significantly enhanced the growth of subcutaneous xenografts. Inhibitors of glutamate receptors such as GYKI52466 and SYM2206 significantly decreased survival of pancreatic cancer cells, suggesting the presence of glutamate signaling in pancreatic cancer. In conclusion, GRIA3 plays a role as a mediator of tumor progression in pancreatic cancer downstream CUX1. To our knowledge, this is the first report to identify a glutamate receptor as a modulator of tumor progression in a solid cancer outside the brain.

Abbreviations

AMPA
α-amino-3-hydroxy-5-methyl-4-isoxazol-propionate
siRNA
small interfering RNA
TRAIL
tumor necrosis factor-related apoptosis-inducing ligand

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1

This work was supported in part by the Deutsche Forschungsgemeinschaft (Mi710/3-1 and KFO210 to P.M.), the Deutsche Krebshilfe (to P.M.), the state of Hesse (LOEWE initiative “tumor and inflammation,” to P.M., M.B., and T.G.), the Behring-Roentgen Foundation (51-0057B to P.M.), and the European Commisson FP6 grant LSHB-CT-2006-018771 (Integrated Project “MolDiag-Paca” to T.G.). This publication reflects only the authors’ views. The European Community is not liable for any use that may be made of the information herein.

2

This article refers to supplementary materials, which are designated by Table W1 and Figures W1 to W6 and are available online at www.neoplasia.com

3

These authors contributed equally to the article.