Glutamate Receptor GRIA3—Target of CUX1 and Mediator of Tumor Progression in Pancreatic Cancer

Abstract

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.

RETRACTED ARTICLE: MicroRNA-330-3p promotes cell invasion and metastasis in non-small cell lung cancer through GRIA3 by activating MAPK/ERK signaling pathway

“…GRIA3 is a subunit of ionotropic glutamate receptors (AMPAR) [39] and was shown to promote tumor progression in glioma [49, 50] and pancreatic cancer [39]. In this study, western blotting and qRT-PCR demonstrated that GRIA3 level was inversely correlated with miR-330-3p expression.…”

CUX1 transcription factors: From biochemical activities and cell-based assays to mouse models and human diseases

“…These findings together with the observation that CUX1 expression is elevated in breast tumors of higher histopathological grade as well as in pancreatic cancer tissues led to the suggestion that CUX1 plays a role in tumor progression (Michl et al, 2005;Ripka et al, 2010a). The Src tyrosine kinase, the WNT5A ligand and the glutamate receptor GRIA3 were shown to be regulated downstream of CUX1 and to mediate some of its effects (Aleksic et al, 2007;Ripka et al, 2007;Ripka et al, 2010b). Whether elevated CUX1 expression, as observed in many human cancers, could stimulate cell motility remained to be verified.…”

“…Studies in various tumor cell types have identified many CUX1-regulated genes, whether direct targets or not, that could contribute to tumorigenicity (Michl et al, 2005;Amiri et al, 2006;Ueda et al, 2007;Harada et al, 2008;Truscott et al, 2008;Cadieux et al, 2009;Kedinger et al, 2009;Siam et al, 2009;Ripka et al, 2010b;Kojima et al, 2011;Sansregret et al, 2011). It is likely that the role of CUX1 in tumor initiation and progression involves a large number of genes that play a role in multiple biological processes (Luo et al, 2009).…”

Expression of Glutamate Receptor Subtype 3 Is Epigenetically Regulated in Podocytes under Diabetic Conditions

“…Pathway analysis of the total of 339 genes showed that altered genes are largely involved in cell division and cell cycle regulation (Table 1). For two hypermethylated genes in our analysis, ESX1, a homeodomain protein, was reported to regulate cell cycle progression and transcription [24-26], and GRIA3 has been shown to promote proliferation in nonneuronal cells [27, 28]. As other glutamate receptors, such as NMDA receptor, have an important function in podocyte biology and glomerular diseases, we selected GRIA3 for further analysis.…”