Glucose deprivation affects the expression of genes encoding cAMP-activated protein kinase and related proteins in U87 glioma cells in ERN1 dependent manner

Abstract

Objective. The aim of this investigation was to study the expression of genes encoding cAMP-activated protein kinase catalytic and regulatory A subunits (PRKACA and PRKAR1A) and related proteins such as cAMP-dependent protein kinase inhibitors A and G (PKIA and PKIG), catalytic subunit A of protein phosphatase 3 (PPP3CA), A-kinase anchoring protein 12 (AKAP12), and praja ring finger ubiquitin ligase 2 (PJA2) in U87 glioma cells in response to glucose deprivation in both control U87 glioma cells and cells with ERN1 (endoplasmic reticulum to nucleus signaling 1) knockdown, the major pathway of the endoplasmic reticulum stress signaling, for evaluation of possible significance of glucose deprivation in ERN1 dependent regulation of glioma growth. Methods. The expression level of PRKA related genes was studied in control (transfected by vector) and ERN1 knockdown U87 glioma cells under glucose deprivation by real-time quantitative polymerase chain reaction. Results. It was shown that the expression level of PRKACA and PKIA genes was down-regulated in control glioma cells treated by glucose deprivation, but PJA2 gene was up-regulated. At the same time, the expression of four other genes (PRKAR1A, PKIG, AKAP12, and PPP3CA) was resistant to this experimental condition. Furthermore, ERN1 knockdown of glioma cells significantly modified the effect glucose deprivation on the expression almost all studied genes. Thus, treatment of glioma cells with inhibited ERN1 enzymatic activity by glucose deprivation lead to a more significant down-regulation of the expression level of PKIA and to suppression PRKAR1A gene expressions. Moreover, the ERN1 knockdown introduced up-regulation of PKIG and AKAP12 gene expressions in glioma cells treated by glucose deprivation and eliminated the sensitivity of PJA2 gene to this experimental condition. Conclusions. Results of this investigation demonstrated that ERN1 knockdown significantly modified the sensitivity of most studied PRKA related gene expressions to glucose deprivation and that these changes are a result of complex interactions of variable endoplasmic reticulum stress related and unrelated regulatory factors and contributed to the suppression of glioma cell proliferation and their possibly chemoresistance.

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

“…The rapid growth of cancers generates microenvironmental changes in regards to nutrient deprivation, thus inducing the activation of endoplasmic reticulum stress signaling pathways, cell proliferation, and survival (Obacz et al 2017;Zhao et al 2017;Obiedat et al 2019;. Furthermore, a better knowledge of tumor responses to nutrient deprivation is required to elaborate better therapeutical strategies of cell sensibilization, based on the blockade of survival mechanisms (Iurlaro et al 2017;Riabovol et al 2019;Teramoto and Katoh 2019;Minchenko et al 2020a, b;Ratushna 2020). Cell proliferation and apoptosis are strongly dependent on glycolysis and glucose level, because there is the molecular connection between metabolism, cell cycle progression, and the delivery of nutrients essen-tial for this purpose (Huber et al 2013;Parzych et al 2019).…”

Classification and biomarker selection in lower-grade glioma using robust sparse logistic regression applied to RNA-seq data

“…The genes selected by the models can be found in Table 4. Among the relevant genes identified in the separation of patients into LGG-a and LGG-od subtypes, several have been reported in the literature as playing a role in gliomas, with the translocase of outer mitochondrial membrane 20 (TOMM20) (Zheng et al, 2022), cAMP-dependent protein kinase inhibitor alpha (PKIA) (Ratushna, 2020), caspase recruitment domain-containing protein 8 (CARD8) (Sharma et al, 2019) and TATAbox binding protein associated factor 12 (TAF12) (Ren et al, 2015;Wijethilake et al, 2020) standing out as genes involved in glioma proliferation and tumorigenesis. These genes also showed among the largest coefficients for rSLR (Figure 5).…”