Background As a newfound type of non-coding RNA, circular RNAs (circRNAs) are involved in various physiological and pathological processes via regulation of gene expression. Increasing evidence shows that aberrantly expressed circRNAs play a crucial role in the initiation and progression of many tumors. However, the functions of different circRNAs in gliomas remain elusive. Methods The levels of circRNAs, miRNAs, and mRNAs were quantified by qPCR. The interaction between circDENND2A and miR-625-5p was determined by luciferase reporter and pull-down assays. The migratory and invasive capabilities of glioma cells were examined by wound healing and Transwell assays. Immunohistochemistry was performed to analyze the HIF1α level in glioma tissues. Results We predicted circDENND2A (has_circ_0002142) to be a hypoxia-responsive circRNA in glioma via a bioinformatic analysis. We found that hypoxia induced the expression of circDENND2A, which promoted migration and invasion of glioma cells. To understand the behaviors of circDENND2A in glioma, we studied the putative miRNAs targeted by circDENND2A and identified circDENND2A as an efficient sponge of miR-625-5p in glioma cells. Phenotype experiments verified that circDENND2A was required for the hypoxia-induced migration and invasion of glioma cells and that this occurred by sponging of miR-625-5p. Notably, glioma tissues overexpressing HIF1α exhibited a high expression of circDENND2A as well as a low expression of miR-625-5p. circDENND2A was negatively correlated with miR-625-5p. Conclusion circDENND2A is required for the hypoxia-induced malignancy of glioma cells and functions by sponging miR-625-5p. Electronic supplementary material The online version of this article (10.1186/s11658-019-0149-x) contains supplementary material, which is available to authorized users.

Hyperthermia (HT) has shown potential in cancer therapy. In particular, it appears to sensitize cancer cells to chemotherapy. However, a major concern associated with HT is that the thermal dosage applied to the tumor cells may also harm the normal tissue cells. Besides, the drugs used in HT are conventional chemotherapy drugs, which may cause serious side effects. The present study demonstrated a novel methodology in HT therapy called thermal cycle (TC)-HT. With this strategy, a therapeutic window with a maximum synergistic effect was created by combining TC-HT with natural compounds, with minimal unwanted cell damage. The natural compound propolis was selected, and the synergistic anticancer effect of TC-HT and propolis was investigated in pancreatic cancer cells. The present results demonstrated for the first time that TC-HT could enhance the anticancer effect of propolis on PANC-1 cancer cells through the mitochondria-dependent apoptosis pathway and cell cycle arrest. Combined treatment greatly suppressed mitochondrial membrane potential, which is an important indicator of damaged and dysfunctional mitochondria. Furthermore, the cell cycle-regulating protein cell division cycle protein 2 was downregulated upon combined treatment, which prevented cellular progression into mitosis. The present study offers the first report, to the best of our knowledge, on the combination of TC-HT with a natural compound for pancreatic cancer treatment. It is anticipated that this methodology may be a starting point for more sophisticated cancer treatments and may thereby improve the quality of life of many patients with cancer.

As the most common type of neurodegenerative diseases (NDDs), Alzheimer’s disease (AD) is thought to be caused mainly by the excessive aggregation of β-amyloid protein (Aβ). However, a growing number of studies have found that reactive oxygen species (ROS) play a key role in the onset and progression of AD. The present study aimed to probe the neuroprotective effect of high-frequency low-intensity pulsed electric field (H-LIPEF) for SH-SY5Y cells against hydrogen peroxide (H2O2) and Aβ-induced cytotoxicity. By looking in a systematic way into the frequency- and amplitude-dependent neuroprotective effect of pulsed electric field (PEF), the study finds that H-LIPEF at 200 Hz produces the optimal protective effect for SH-SY5Y cells. The underlying mechanisms were confirmed to be due to the activation of extracellular signal-regulated kinase (ERK) pathway and the downstream prosurvival and antioxidant proteins. Because the electric field can be modified to focus on specific area in a non-contact manner, the study suggests that H-LIPEF holds great potential for treating NDDs, whose effect can be further augmented with the administering of drugs or natural compounds at the same time.

Structural origin of substrate-enzyme recognition remains incompletely understood. In the model enzyme system of serine protease, canonical anti-parallel ␤-structure substrate-enzyme complex is the predominant hypothesis for the substrate-enzyme interaction at the atomic level. We used factor Xa (fXa), a key serine protease of the coagulation system, as a model enzyme to test the canonical conformation hypothesis. More than 160 fXa-cleavable substrate phage variants were experimentally selected from three designed substrate phage display libraries. These substrate phage variants were sequenced and their specificities to the model enzyme were quantified with quantitative enzyme-linked immunosorbent assay for substrate phage-enzyme reaction kinetics. At least three substrate-enzyme recognition modes emerged from the experimental data as necessary to account for the sequence-dependent specificity of the model enzyme. Computational molecular models were constructed, with both energetics and pharmacophore criteria, for the substrate-enzyme complexes of several of the representative substrate peptide sequences. In contrast to the canonical conformation hypothesis, the binding modes of the substrates to the model enzyme varied according to the substrate peptide sequence, indicating that an ensemble of binding modes underlay the observed specificity of the model serine protease.Serine proteases recognize peptide sequences as substrates with a spectrum of specificity (1), for which the structural origin remains largely unclear (2, 3). The enzyme family is one of the most important model families in enzymology as about onethird of proteases (coded in about 2% of human genome) can be classified as serine proteases and many of the serine proteases are involved in important physiological regulation and pathogenic dysfunction (1). Ref. 4, and references therein). Still, the enzyme-substrate transition state complex structures have been difficult to be elucidated (5), partly due to the rapid hydrolysis of the substrate and partly due to the rapid dissociation of the products from the active site. Hence the structural origin on the substrate specificity of serine proteases has been incompletely resolved, hampering critical understanding toward enzyme-substrate recognition and its implications in inhibitor design and substrate specificity engineering.Models of enzyme-substrate transition state complexes have been proposed on the basis of the three-dimensional structures of serine protease-inhibitor complexes. Invariably in the models and thus dubbed canonical conformation, the peptide substrate binds to the enzyme in ␤-strand conformation, anti-parallel to the corresponding ␤-strand (residues 214 -217 in chymotrypsin number) in the serine protease (see Refs. 2-6 for reviews). However, accumulating evidence supporting alternative models suggests that the canonical conformation is not universally applicable to serine protease-substrate complexes (5-8). Using factor Xa as a model system, we asked if the canonical conformation hypo...

Post-operative epidural fibrosis is a biological response after laminectomy that may lead to clinical symptoms, such as radicular pain. An ideal material for prevention of epidural fibrosis should be able to inhibit fibroblast adhesions and reduce formation of scar tissue. An injectable hydrogel would be the material of choice for this purpose, since it could fill an irregular surgical defect completely, gelate in situ and be delivered in a minimally-invasive manner. The objective of this study was to evaluate, in vitro and in vivo, the cytocompatibility and anti-adhesive effect of an oxidised hyaluronic acid/adipic acid dihydrazide (oxi-HA/ADH) hydrogel. Different cell types present in the spine were used to test the cytocompatibility of the hydrogel. The hydrogel extraction medium had no deleterious effects on neural cells (PC-12), but reduced fibroblasts viability (NIH/3T3). Although the hydrogel did not change the release of lactate dehydrogenase from myoblasts (C2C12) and Schwann cells (RSC96), the extraction medium concentration slightly affected the mitochondrial activity of these two cell types. qPCR showed that the hydrogel down-regulated S100a and P4hb expression in NIH/3T3 cells, supporting the hypothesis that the hydrogel might inhibit fibroblast activity. The animal study showed a reduction of scar tissue formation as well as severity of adhesion between scar tissue and the dura mater in a rat laminectomy model. Superficially, the peel-off test showed significantly decreased tenacity. In conclusion, the oxi-HA/ADH hydrogel is a promising injectable and thermosensitive material for prevention of post-operative epidural fibrosis.