The expression of DNAJB9 in normal human astrocytes is more sensitive to nanographene oxide than in glioblastoma cells

Abstract

Objective. Nanographene oxide (nGO) nanoparticles (NPs) have unique properties and are widely used in various fields, including biomedicine. These NPs, however, also exhibit toxic ef­fects and therefore, the understanding of the molecular mechanism of nGO toxicity is very im­portant mainly for the nanomedicine, especially the cancer therapy. This study aimed to examine the impact of nGO NPs on the expression of genes associated with endoplasmic reticulum (ER) stress, proliferation, and cancerogenesis in both normal human astrocytes and U87MG glioblas­toma cells. Methods. Normal human astrocytes line NHA/TS and U87MG glioblastoma cells stable trans­fected by empty vector or dnERN1 (dominant-negative construct of ERN1) were exposed to low doses of nGO (1 and 4 ng/ml) for 24 h. RNA was extracted from the cells and used for cDNA syn­thesis. The expression levels of DNAJB9, EDEM1, DDIT3, ATF3, ATF4, TOB1, and IDH2 mRNAs were measured by quantitative polymerase chain reaction and normalized to ACTB mRNA. Results. We showed that treatment of normal astrocytes and glioblastoma cells by relatively small doses of nGO (1 and 4 ng/ml for 24 h) affected the expression level of DNAJB9, EDEM1, DDIT3, ATF3, ATF4, TOB1, and IDH2 mRNAs, but the sensitivity of all studied mRNA expres­sions to these NPs was significantly higher in normal astrocytes than in glioblastoma cells. The impact of nGO on these gene expressions is mediated by ER stress because ERN1 knockdown sup­presses the effect of these nanoparticles in glioblastoma cells. Conclusion. The data obtained demonstrate that the low doses of nGO disturbed the functional integrity of the genome preferentially through ER stress signaling and exhibit a more pronounced genotoxic effect in the normal astrocytes than the glioblastoma cells.