Effect of Benzimidazole Compound on Endoplasmic Reticulum Stress and Unfolded Protein Response (UPR) Signaling Pathway in Hydrogen Peroxide (H2O2)-Induced BEAS-2B Cells

The primary objective of this work was to elucidate the impact of endoplasmic reticulum stress on both mRNA level and protein expression on BEAS-2B cells under oxidative stress conditions. The secondary objective was to assess the effect of RHE 231, a benzimidazole compound, on unfolded protein response signaling pathway. To identify non-toxic doses, cell viability under H2O2 and RHE 231 exposure was evaluated via the MTT assay, while cellular lipid oxidation due to H2O2 was measured using the MDA assay. Quantitative real-time PCR was employed to analyze ATF6, PERK, IRE1α, and GRP78 gene expression levels, while IRE1α and ATF4 protein levels were assessed through western blot method. Malondialdehyde levels were notably higher than the control group at ten and twenty µM concentrations at 24 hours. Significant increases in PERK and IRE1α mRNA levels were detected in the groups in which benzimidazole compound and hydrogen peroxide were applied combined than control group. No significant differences in GRP78 and ATF6 mRNA expression levels were detected in any group relative to the control group. Western blot analysis revealed that ATF4 and IRE1 protein expression was higher in the H2O2 alone and combined with benzimidazole compound groups than control group. In BEAS-2B cells, H2O2-induced oxidative damage led to the activation of ER stress and launch of the unfolded protein response pathway. Although protein levels diminished in certain groups treated with the benzimidazole compound, it was observed that this decrease did not exhibit a dose-dependent pattern.