ERN1 knockdown modifies the impact of glucose and glutamine deprivations on the expression of EDN1 and its receptors in glioma cells

Abstract

Objective. The aim of the present investigation was to study the impact of glucose and gluta-mine deprivations on the expression of genes encoding EDN1 (endothelin-1), its cognate receptors (EDNRA and EDNRB), and ECE1 (endothelin converting enzyme 1) in U87 glioma cells in response to knockdown of ERN1 (endoplasmic reticulum to nucleus signaling 1), a major signaling pathway of endoplasmic reticulum stress, for evaluation of their possible implication in the control of glioma growth through ERN1 and nutrient limitations. Methods. The expression level of EDN1, its receptors and converting enzyme 1 in control U87 glioma cells and cells with knockdown of ERN1 treated by glucose or glutamine deprivation by quantitative polymerase chain reaction was studied. Results. We showed that the expression level of EDN1 and ECE1 genes was significantly up-regulated in control U87 glioma cells exposure under glucose deprivation condition in comparison with the glioma cells, growing in regular glucose containing medium. We also observed up-regulation of ECE1 gene expression in U87 glioma cells exposure under glutamine deprivation as well as down-regulation of the expression of EDN1 and EDNRA mRNA, being more significant for EDN1. Furthermore, the knockdown of ERN1 signaling enzyme function significantly modified the response of most studied gene expressions to glucose and glutamine deprivation conditions. Thus, the ERN1 knockdown led to a strong suppression of EDN1 gene expression under glucose deprivation, but did not change the effect of glutamine deprivation on its expression. At the same time, the knockdown of ERN1 signaling introduced the sensitivity of EDNRB gene to both glucose and glutamine deprivations as well as completely removed the impact of glucose deprivation on the expression of ECE1 gene. Conclusions. The results of this study demonstrated that the expression of endothelin-1, its receptors, and ECE1 genes is preferentially sensitive to glucose and glutamine deprivations in gene specific manner and that knockdown of ERN1 significantly modified the expression of EDN1, EDNRB, and ECE1 genes in U87 glioma cells. It is possible that the observed changes in the expression of studied genes under nutrient deprivation may contribute to the suppressive effect of ERN1 knockdown on glioma cell proliferation and invasiveness.

ERN1 dependent impact of glutamine and glucose deprivations on the pyruvate dehydrogenase genes expression in glioma cells

“…These results clearly demonstrated that the expression of PDHA1, PDHB, DLAT, and DLD genes is controlled by glutamine supply and that this control is ER stress dependent particularly through ERN1 signaling. This is in accordance with the data our previous studies (Minchenko et al , 2020(Minchenko et al , 2021Tsymbal et al 2016;Krasnytska et al 2022) as well as studies of other authors (Drogat et al 2007). The changes in PDHA1 and PDHB genes expression under glutamine deprivation are in agreement with data of Yetkin-Arik et al (2019) indicating that silencing of PDHA1 expression prevents the proliferation of HUVECs, because this enzyme of PDH complex is a crucial regulator of pyruvate metabolic pathways (Zaher et al 2021).…”

“…Glutamine and glucose supply as well as endoplasmic reticulum (ER) stress are very important and complementary factors for the tumor growth. This is also confirmed by the fact that inhibition of endoplasmic reticulum to nucleus signaling 1 (ERN1)/inositol requiring enzyme 1 (IRE1) modifies the effect of glutamine and glucose deprivations on the expression of numerous genes (Minchenko et al , 2015a(Minchenko et al , 2020(Minchenko et al , 2021Tsymbal et al 2016Tsymbal et al , 2020Riabovol et al 2019;Krasnytska et al 2022). Bioinformatics profiling identifies a glucose-related risk signature for the malignancy of glioma (Zhao et al 2017).…”

RNA Sequencing in Hypoxia-Adapted T98G Glioblastoma Cells Provides Supportive Evidence for IRE1 as a Potential Therapeutic Target

“…Minchenko and colleagues demonstrated hypoxic activation of the UPR and upregulation of IRE1 in GBM. Using U87 cell lines with constitutive inhibition of IRE1, they document a complex pattern of downstream gene regulation induced by hypoxia and controlled by IRE1 function [ 11 , 33 , 34 , 35 ].…”

ERN1 dependent impact of glucose and glutamine deprivations on PBX3, PBXIP1, PAX6, MEIS1, and MEIS2 genes expression in U87 glioma cells

“…We also showed that ERN1 knockdown in glioma cells removes the up-regulation of PAX6 and PBXIP1 genes expression introduced by glutamine deprivation and enhances the sensitivity of PBX3 gene expression to this experimental condition. The functional significance of these changes in the expression of PAX6, PBX3, PBXIP1, and MEIS2 genes, which preferentially have diverse impacts on cell proliferation and tumor growth, is under glutamine deprivation condition possibly connected with glutamine deficiency mediated by ERN1 (Auf et al 2010;Zha et al 2014;Li et al 2016Li et al , 2021Khumukcham and Manavathi 2021;Minchenko et al 2021;Wen et al 2021;Wang et al 2022). It is also possible that the endoplasmic reticulum stress mediated by ERN1 creates the resistance to glutamine deprivation and that ERN1 blockade lowers this resistance.…”