Down-Regulation of CEND1 Expression Contributes to The Progression and Temozolomide Resistance of Glioma

OBJECTIVE: This study was conducted to clarify the expression characteristics of cell cycle exit and neuronal differentiation 1 (CEND1) in glioma and its effects on the proliferation, migration, invasion, and resistance to temozolomide (TMZ) of glioma cells. MATERIALS AND METHODS: In this experimental study, CEND1 expression in glioma tissues and its relationship with patients’ survival were analyzed through bioinformatics. Quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemistry were performed to detect CEND1 expression in glioma tissues. The cell counting kit-8 (CCK-8) method was adopted to detect cell viability and the effects of different concentrations of TMZ on the inhibition rate of glioma cell proliferation, and the median inhibitory concentration of TMZ (IC50 value) was calculated. 5-Bromo- 2'-deoxyuridine (BrdU), wound healing and Transwell assays were performed to evaluate the impacts of CEND1 on glioma cell proliferation, migration, and invasion. Besides, the Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, Gene Ontology (GO) analysis, and Gene Set Enrichment Analysis (GSEA) were applied to predict the pathways regulated by CEND1. Nuclear factor-kappa B p65 (NF-κB p65) and phospho-p65 (p-p65) expression were detected by Western blot. RESULTS: CEND1 expression was reduced in glioma tissues and cells, and its low expression was significantly associated with the shorter survival of glioma patients. CEND1 knockdown promoted glioma cell growth, migration, and invasion, and increased the IC50 value of TMZ, whereas up-regulating CEND1 expression worked oppositely. Genes co-expressed with CEND1 were enriched in the NF-κB pathway, and knocking down CEND1 facilitated p-p65 expression, while CEND1 overexpression suppressed p-p65 expression. CONCLUSION: CEND1 inhibits glioma cell proliferation, migration, invasion, and resistance to TMZ by inhibiting the NF- κB pathway.