Effect of Benzimidazole Compound on Endoplasmic Reticulum Stress and Unfolded Protein Response Signaling Pathways in Hydrogen Peroxide-Induced BEAS-2B Cells

Abstract

Abstract The main aim of the study was to reveal the effects of endoplasmic reticulum (ER) stress on human bronchial epithelial cells BEAS-2B at gene and protein levels under oxidative stress conditions. The second aim of the study was to investigate whether the benzimidazole compound RHE-231 has a protective effect on ER stress and unfolded protein response (UPR) signaling pathways. To determine subtoxic doses of H2O2 and RHE-231 on cell viability were examined using MTT assay. To determine cellular lipid oxidation of H2O2 was examined using MDA assay. PERK, ATF6, IRE1α, GRP78 mRNA levels and ATF4 and IRE1α protein levels were investigated by quantitative real-time PCR and western blotting, respectively. MDA levels were significantly higher at concentrations of 10 and 20 µM for 24 h compared to the control group. A significant increase in IRE1α and PERK gene expression levels were found at groups of 20 µM H2O2 + 5 µM RHE-231 and 20 µM H2O2 + 10 µM RHE-231 compared to the control group. There were no significant difference observed in ATF6 and GRP78 gene expression levels in any group compared to the control group. According to the results of the western blot analysis, a significant increase were observed at groups of 20 µM H2O2, 20 µM H2O2 + 5 µM RHE-231, and 20 µM H2O2 + 10 µM RHE-231 in the expression of IRE1α and ATF4 compared to the control group. H2O2 mediated oxidative stress in BEAS-2B cells, stimulated ER stress, and activated the UPR pathway. Protein expression was also decreased in some samples where the benzimidazole compound was tested, but this was not in a concentration-dependent manner.