Objective To investigate the effects and mechanisms of LINC00657 on oxidative glucose deprivation (OGD)-induced injury in mouse hippocampal neurons. Methods Mouse hippocampal neuron cell line HT22 was given OGD treatment to establish an injury model, with normally cultured HT22 cells as controls. The si-NC, si-LINC00657, microRNA(miR)-NC, and miR-224-3p mimics were transfected into HT22 cells, followed by OGD treatment. Co-transfection of si-LINC00657 and anti-miR-NC, or co-transfection of si-LINC00657 and anti-miR-224-3p, was performed in HT22 cells before OGD treatment. Real-time quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used to detect the relative expression levels of LINC00657 and miR-224-3p. CCK-8 assay and flow cytometry were used to detect cell viability and apoptosis rate, respectively. Kits were used to detect the activities of lactate dehydrogenase (LDH), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and the level of malondialdehyde (MDA). Dual-luciferase reporter gene assay was used to detect the effect of miR-224-3p overexpression on the luciferase activity of wild-type LINC00657 vector (WT-LINC00657) and mutant LINC00657 vector (MUT-LINC00657). Results Compared with controls, the expression of LINC00657 was upregulated and the expression of miR-224-3p was downregulated in OGD-induced HT22 cells (P < 0.05). Compared with transfection of si-NC or miR-NC, transfection of si-LINC00657 or miR-224-3p mimics resulted in increased cell viability, SOD activity, and GSH-Px activity, as well as decreased apoptosis rate, LDH activity, and MDA level(P < 0.05). Overexpression of miR-224-3p reduced the luciferase activity of WT-LINC00657 (P < 0.05). Compared with cells co-transfected with si-LINC00657 and anti-miR-NC, cells co-transfected with si-LINC00657 and anti-miR-224-3p showed decreased cell viability, increased apoptosis rate, increased LDH activity and MDA level, and decreased SOD and GSH-Px activities (P < 0.05). Conclusion Interference with LINC00657 can promote cell proliferation, inhibit apoptosis and oxidative stress response by upregulating miR-224-3p, thereby alleviating OGD-induced injury in mouse hippocampal neurons.

Resistance of tumor cells is a complex biological process involving multiple mechanisms and factors, in which anti-apoptosis is the most important cause of drug resistance. Previous studies have shown that the DNA binding activity of Runt related transcription factor 3 (RUNX3) increased prominently in Herceptin resistant gastric cancer cells (NCI N87R) while the relevance of which to drug resistance has not yet been confirmed. In this study, we employed CRISPR/Cas9 to establish RUNX3 knock-out cell line (△RUNX3/NCI N87R) to investigate the functions of RUNX3 in Herceptin resistance of NCI N87R cells and its potential mechanisms. We investigated proteomics profiling of △RUNX3/NCI N87R cells based on label free quantitative proteomics. Differentially expressed proteins were screened out according to fold change and significance level between △RUNX3/NCI N87R and NCI N87R cells. Pathway enrichment analysis was done using GeneAnalytics database, and gene ontology analysis was conducted by DAVID Bioinformatics Resources database. Protein-protein interaction networks were constructed based on STRING database. The results showed that △RUNX3/NCI N87R cells increased the sensitivity to Herceptin. Proteomic data demonstrated that the expression of 577 genes changed significantly in △RUNX3/NCI N87R cells, among which 191 genes were up-regulated while 386 ones down-regulated comparing with NCI N87R cells. Pathway analysis showed that autophagy, cell cycle, apoptosis, mitochondrial fatty acid β oxidation, neurogenic locus notch homolog protein 1 (NOTCH1), mammalian target of rapamycin (mTOR), Hedgehog and DNA damage response pathways exhibited notable changes based on pathway enrichment ratio and significance level (P < 0.05). These results indicated that RUNX3 knock-out altered multiple signaling pathways of NCI N87R cells. Western blotting manifested that the expression of autophagy regulatory molecules autophagy-related protein (ATG) 13, 7 and BECN1 increased remarkably while cell cycle molecules serine/threonine-protein kinase Chk2 (CHEK2) and apoptosis regulator Bcl-2 (BCL2) decreased prominently in △RUNX3/NCI N87R cells. The p-AKT expression decreased significantly in △RUNX3/NCI N87R cells compared with NCI N87R cells (P < 0.01) and was suppressed by Herceptin. These results indicated that RUNX3 knock-out altered cell cycle, increased inhibition to p-AKT by Herceptin, promoted autophagy and induced cell apoptosis of NCI N87R cells. These results suggested that RUNX3 may be a potential therapeutic target for reversing or reducing Herceptin resistance in gastric cancer cells.