ERN1 knockdown modifies the effect of glucose deprivation on homeobox gene expressions in U87 glioma cells

Abstract

Objective. The aim of the present investigation was to study the expression of genes encoding homeobox proteins ZEB2 (zinc finger E-box binding homeobox 2), TGIF1 (TGFB induced factor homeobox 1), SPAG4 (sperm associated antigen 4), LHX1 (LIM homeobox 1), LHX2, LHX6, NKX3-1 (NK3 homeobox 1), and PRRX1 (paired related homeobox 1) in U87 glioma cells in response to glucose deprivation in control glioma cells and cells with knockdown of ERN1 (endoplasmic reticulum to nucleus signaling 1), the major pathway of the endoplasmic reticulum stress signaling, for evaluation of it possible significance in the control of glioma growth through ERN1 signaling and chemoresistance.Methods. The expression level of homeobox family genes was studied in control (transfected by vector) and ERN1 knockdown U87 glioma cells under glucose deprivation condition by real-time quantitative polymerase chain reaction.Results. It was shown that the expression level of ZEB2, TGIF1, PRRX1, and LHX6 genes was up-regulated in control glioma cells treated by glucose deprivation. At the same time, the expression level of three other genes (NKX3-1, LHX1, and LHX2) was down-regulated. Furthermore, ERN1 knockdown of glioma cells significantly modified the effect glucose deprivation condition on the expression almost all studied genes. Thus, treatment of glioma cells without ERN1 enzymatic activity by glucose deprivation condition lead to down-regulation of the expression level of ZEB2 and SPAG4 as well as to more significant up-regulation of PRRX1 and TGIF1 genes. Moreover, the expression of LHX6 and NKX3-1 genes lost their sensitivity to glucose deprivation but LHX1 and LHX2 genes did not change it significantly.Conclusions. The results of this investigation demonstrate that ERN1 knockdown significantly modifies the sensitivity of most studied homeobox gene expressions to glucose deprivation condition and that these changes are a result of complex interaction of variable endoplasmic reticulum stress related and unrelated regulatory factors and contributed to glioma cell growth and possibly to their chemoresistance.

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

“…It is interesting to note that endoplasmic reticulum stress and glucose as well as glutamine level are very important and complementary factors for tumor growth and that ERN1 mediated stress signaling can significantly modify the effects of glutamine and glucose deprivations as well as hypoxia on numerous gene expressions (Minchenko et al 2014(Minchenko et al , 2016(Minchenko et al , 20172019;Zhao et al 2017;Tsymbal et al 2020). However, the detailed molecular mechanisms of the interaction of hypoxia and glucose deprivation with ERN1 mediated stress signaling pathway are complex yet and warrant further study.…”

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

“…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).…”