Glioblastoma (GBM) is a primary malignant tumor characterized by high infiltration and angiogenesis in the brain parenchyma. Glioma stem cells (GSCs), a heterogeneous GBM cell type with the potential for self-renewal and differentiation to tumor cells, are responsible for the high malignancy of GBM. The purpose of the present study was to investigate the roles of significantly differentially expressed genes between GSCs and GBM cells in GBM progression. The gene profiles GSE74304 and GSE124145, containing 10 GSC samples and 12 GBM samples in total, were obtained from the Gene Expression Omnibus (GEO) database. The overlapping differentially expressed genes were identified with GEO2R tools and Venn software online. Subsequently, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analysis was performed on the 41 upregulated and 142 downregulated differentially expressed genes in GSCs compared with in GBM cells via the DAVID website. Protein-protein interaction and module analyses in Cytoscape with the STRING database revealed 21 hub genes that were downregulated in GSCs compared with in GBM cells. Survival analysis conducted via the GEPIA2 website revealed that low expression levels of the hub genes prolyl 4-hydroxylase subunit α2 (P4HA2), TGF-β induced, integrin subunit α3 and thrombospondin 1 were associated with significantly prolonged survival time in patients with GBM. Further experiments were performed focusing on P4HA2. Reverse transcription-quantitative PCR was used to detect P4HA2 gene expression. In agreement with the bioinformatics analysis, P4HA2 expression was higher in U87 cells than in GSCs. Cell Counting Kit-8, EdU incorporation, cell cycle analysis, wound healing and Transwell assays demonstrated that the cell proliferation and migration increased after P4HA2 overexpression and decreased after P4HA2-knockdown. In conclusion, the present study demonstrated that low P4HA2 expression in GSCs promoted GBM cell proliferation and migration, suggesting that P4HA2 may act as a switch in the transition from GSCs to GBM cells.

No abstract

The transcription factor Brn4 exhibits vital roles in the embryonic development of the neural tube, inner ear, pancreas islet, and neural stem cell differentiation. Our previous studies have shown that Brn4 promotes neuronal differentiation of hippocampal neural stem cells (NSCs). However, its mechanism is still unclear. Here, starting from the overlapping genes between RNA-seq and ChIP-seq results, we explored the downstream target genes that mediate Brn4-induced hippocampal neurogenesis. There were 16 genes at the intersection of RNA-seq and ChIP-seq, among which the Lama2 and Samsn1 levels can be upregulated by Brn4, and the combination between their promoters and Brn4 was further determined using ChIP and dual luciferase reporter gene assays. EdU incorporation, cell cycle analysis, and CCK-8 assay indicated that Lama2 and Samsn1 mediated the inhibitory effect of Brn4 on the proliferation of hippocampal NSCs. Immunofluorescence staining, RT-qPCR, and Western blot suggested that Lama2 and Samsn1 mediated the promoting effect of Brn4 on the differentiation of hippocampal NSCs into neurons. In conclusion, our study demonstrates that Brn4 binds to the promoters of Lama2 and Samsn1, and they partially mediate the regulation of Brn4 on the proliferation inhibition and neuronal differentiation promotion of hippocampal NSCs.

POU3F4, a transcription factor (TF), has been proved to be critical regulator of inner ear and pancreas development and neurogenesis. Despite growing evidence confirming the indispensable role of POU3F4 in carcinogenesis of specific cancers, the pan-cancer assessment of POU3F4 remains scanty. As a result, we aimed at studying the prognostic value of POU3F4 in thirty-three cancers and to study the underlying function in immunity. On the grounds of data from The Cancer Genome Atlas, Cancer Cell Line Encyclopedia, Genotype Tissue-Expression and Gene Set Cancer Analysis, we made use of numerous bioinformatics ways to study the prospective carcinogenic effects of POU3F4, DNA methylation, RNA methylation, tumor mutation burden (TMB), mismatch repair (MMR) gene, microsatellite instability (MSI), POU3F4-prognosis interrelation, and immune cell infiltration (ICI) in discrepant tumors. The analysis yielded that the POU3F4 expression was at a low rate in most cancers, while it was higher in breast invasive carcinoma, glioblastoma multiforme, liver hepatocellular carcinoma, and thyroid carcinoma. Additionally, POU3F4 had a link with the prognosis of discrepant cancers, either positively or negatively. Expression of POU3F4 showed relevance to MSI (4 cancer types) and TMB (6 cancer types), and exhibited striking relevance to DNA methylation (13 cancer types) and RNA methylation (most cancers). Additionally, its expression was associated with tumor immune microenvironment, immune-related genes, ICI and drug resistance in different cancers. In vitro experiments had shown that POU3F4 could increase cell viability, proliferation and migration of glioma cells. Our research reveals that concerning the indispensable function in carcinogenesis and tumor immunity, POU3F4 is deemed as a prognostic hallmark in discrepant malignancies.