Human marrow stromal cells secrete microRNA-375-containing exosomes to regulate glioma progression.

It is well established that human marrow stromal cells (hMSCs) can directly migrate towards tumor microenvironments associated with tumor formation and intracellular communication. Gene regulatory networks in tumors may be targeted by microRNAs (miRNAs), especially those derived in exosomes from hMSCs. However, the potential functional roles of hMSCs in glioma cell growth still remain controversial. Therefore, this study aimed at exploring the regulatory mechanisms of hMSC exosomal microRNA-375 (miR-375) in glioma. Microarray analysis was used to initially screen out glioma-related genes. The interaction between miR-375 and solute carrier family 31 member 1 (SLC31A1) was confirmed by dual-luciferase reporter gene assay. miR-375 and SLC31A1 expression in glioma cells were determined. Glioma cells were initially exposed to exosomes derived from hMSCs treated with miR-375. Subsequently, the rates of proliferation, migration, invasion and apoptosis were determined in glioma cells using in vitro assays. The effects of exosomal miR-375 from hMSCs on tumor growth in vivo were also measured using xenograft tumor in nude mice. We found that miR-375 and SLC31A1 showed significantly lower and higher expression of glioma cells respectively. Additionally, restored miR-375 expression resulted in suppressed cell proliferation, migration and invasion, and increased apoptosis by targeting SLC31A1. Next, in vitro experiments demonstrated that hMSC-derived exosomes overexpressing miR-375 promoted apoptosis while suppressing proliferation, migration and invasion. Furthermore, in vivo experiments confirmed the negative regulatory effects of hMSC-derived exosomes with overexpressed miR-375. We conclude that exosomal miR-375 from hMSCs inhibits glioma cell progression through SLC31A1 suppression, and ultimately serves as a potential target in the treatment of gliomas.

Identification of Key Candidate Proteins and Pathways Associated with Temozolomide Resistance in Glioblastoma Based on Subcellular Proteomics and Bioinformatical Analysis.

TMZ resistance remains one of the main reasons why treatment of glioblastoma (GBM) fails. In order to investigate the underlying proteins and pathways associated with TMZ resistance, we conducted a cytoplasmic proteome research of U87 cells treated with TMZ for 1 week, followed by differentially expressed proteins (DEPs) screening, KEGG pathway analysis, protein-protein interaction (PPI) network construction, and validation of key candidate proteins in TCGA dataset. A total of 161 DEPs including 65 upregulated proteins and 96 downregulated proteins were identified. Upregulated DEPs were mainly related to regulation in actin cytoskeleton, focal adhesion, and phagosome and PI3K-AKT signaling pathways which were consistent with our previous studies. Further, the most significant module consisted of 28 downregulated proteins that were filtered from the PPI network, and 9 proteins (DHX9, HNRNPR, RPL3, HNRNPA3, SF1, DDX5, EIF5B, BTF3, and RPL8) among them were identified as the key candidate proteins, which were significantly associated with prognosis of GBM patients and mainly involved in ribosome and spliceosome pathway. Taking the above into consideration, we firstly identified candidate proteins and pathways associated with TMZ resistance in GBM using proteomics and bioinformatic analysis, and these proteins could be potential biomarkers for prevention or prediction of TMZ resistance in the future.

The purine receptor P2X7R regulates the release of pro-inflammatory cytokines in human craniopharyngioma.

Craniopharyngiomas (CPs) are usually benign, non-metastasizing embryonic malformations originating from the sellar area. They are, however, locally invasive and generate adherent interfaces with the surrounding brain parenchyma. Previous studies have shown the tumor microenvironment is characterized by a local abundance of adenosine triphosphate (ATP), infiltration of leukocytes and elevated levels of pro-inflammatory cytokines that are thought to be responsible, at least in part, for the local invasion. Here, we examine whether ATP, via the P2X7R, participates in the regulation of cytokine expression in CPs. The expression of P2X7R and pro-inflammatory cytokines were measured at the RNA and protein levels both in tumor samples and in primary cultured tumor cells. Furthermore, cytokine modulation was measured after manipulating P2X7R in cultured tumor cells by siRNA-mediated knockdown, as well as pharmacologically by using selective agonists and antagonists. The following results were observed. A number of cytokines, in particular IL-6, IL-8 and MCP-1, were elevated in patient plasma, tumor tissue and cultured tumor cells. P2X7R was expressed in tumor tissue as well as in cultured tumor cells. RNA expression as measured in 48 resected tumors was positively correlated with the RNA levels of IL-6, IL-8 and MCP-1 in tumors. Furthermore, knockdown of P2X7R in primary tumor cultures reduced, and stimulation of P2XR7 by a specific agonist enhanced the expression of these cytokines. This latter stimulation involved a Ca2+-dependent mechanism and could be counteracted by the addition of an antagonist. In conclusion, the results suggest that P2X7R may promote IL-6, IL-8 and MCP-1 production and secretion and contribute to the invasion and adhesion of CPs to the surrounding tissue.