The functions and applications of extracellular vesicles derived from Mycobacterium tuberculosis.

Extracellular vesicles (EVs) originating from bacteria function critical roles in bacterial biologic physiology and host-pathogen interactions. Mycobacterium tuberculosis (M. tuberculosis) produces EVs both in vitro and in vivo, with membrane-bound nanoparticles facilitating the transmission of biological molecules including lipids, proteins, nucleic acids and glycolipids, while interacting remotely with the host. Although studies of EVs in mycobacterial infections is still in its infancy, it has already revealed an entirely new aspect of M. tuberculosis-host interactions that may have implications for tuberculosis (TB) pathogenesis. In this review, we discuss the significant functions of M. tuberculosis EVs in elucidating the mechanisms underlying vesicle biogenesis and modulating cellular immune responses, as well as the recent advances and challenges in the development of novel preventive and therapeutic or diagnostic strategies against TB.

RNA binding proteins in extracellular vesicles and their potential value for cancer diagnosis and treatment (Review).

Extracellular vesicles (EVs) are spherical bilayer membrane vesicles released by cells into extracellular spaces and body fluids, including plasma and synovial fluid. EV cargo comprises various biomolecules, such as proteins, DNA, mRNAs, non­coding RNAs, lipids and metabolites. By delivering these bioactive molecules to recipient cells, EVs mediate intercellular communications and play a critical role in maintaining cellular homeostasis and promoting pathological progression. Of note, cells can selectively sort these bioactive molecules (particularly RNAs) into EVs for secretion, as well as regulate cell­cell communications. RNA­binding proteins (RBPs) are a large class of proteins capable of binding to RNA molecules and function in regulating RNA metabolism. There is increasing evidence to indicate that RBPs can be delivered to receipt cells to influence their cell biology and play a significant role in the sorting of coding and non­coding RNAs in EVs. The present review summarized the current knowledge on EV­associated RBPs, their functions in tumorigenesis and RBP­related exosome engineering. It is hoped that the present review may provide novel insight into RBPs and targeted cancer treatment.

Research Progress on the Etiology and Pathogenesis of Alzheimer's Disease from the Perspective of Chronic Stress.

Due to its extremely complex pathogenesis, no effective drugs to prevent, delay progression, or cure Alzheimer's disease (AD) exist at present. The main pathological features of AD are senile plaques composed of ß-amyloid, neurofibrillary tangles formed by hyperphosphorylation of the tau protein, and degeneration or loss of neurons in the brain. Many risk factors associated with the onset of AD, including gene mutations, aging, traumatic brain injury, endocrine and cardiovascular diseases, education level, and obesity. Growing evidence points to chronic stress as one of the major risk factors for AD, as it can promote the onset and development of AD-related pathologies via a mechanism that is not well known. The use of murine stress models, including restraint, social isolation, noise, and unpredictable stress, has contributed to improving our understanding of the relationship between chronic stress and AD. This review summarizes the evidence derived from murine models on the pathological features associated with AD and the related molecular mechanisms induced by chronic stress. These results not only provide a retrospective interpretation for understanding the pathogenesis of AD, but also provide a window of opportunity for more effective preventive and identifying therapeutic strategies for stress-induced AD.

Machine learning algorithm and deep neural networks identified a novel subtype in hepatocellular carcinoma.

BACKGROUND: Hepatocellular carcinoma (HCC) is one of the most common malignant tumors. Due to the lack of specific characteristics in the early stage of the disease, patients are usually diagnosed in the advanced stage of disease progression. OBJECTIVE: This study used machine learning algorithms to identify key genes in the progression of hepatocellular carcinoma and constructed a prediction model to predict the survival risk of HCC patients. METHODS: The transcriptome data and clinical information were downloaded from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO). The differential expression analysis and COX proportional-hazards model participated in the identification of survival-related genes. K-Means, Random forests, and LASSO regression are involved in identifying novel subtypes of HCC and screening key genes. The prediction model was constructed by deep neural networks (DNN), and Gene Set Enrichment Analysis (GSEA) reveals the metabolic pathways where key genes are located. RESULTS: Two subtypes were identified with significantly different survival rates (p< 0.0001, AUC = 0.720) and 17 key genes associated with the subtypes. The accuracy rate of the deep neural network prediction model is greater than 93.3%. The GSEA analysis found that the survival-related genes were significantly enriched in hallmark gene sets in the MSigDB database. CONCLUSIONS: In this study, we used machine learning algorithms to screen out 17 genes related to the survival risk of HCC patients, and trained a DNN model based on them to predict the survival risk of HCC patients. The genes that make up the model are all key genes that affect the formation and development of cancer.

ADAR1 Prevents R-loop Accumulation-Driven ATR Pathway Activation in Ovarian Cancer.

Adenosine (A)-to-inosine (I) RNA editing is the most prevalent RNA editing mechanism, in which adenosine deaminase acting on RNA 1 (ADAR1) is a major adenosine deaminase. Increasing evidence suggests that editing dysregulation of ADAR1 plays an important role in human tumorigenesis, while the underlying mechanism remains elusive. Here, we demonstrated that ADAR1 was highly expressed in ovarian cancer tissues and negatively correlated with progression free survival of ovarian cancer patients. Importantly, silence of ADAR1 repressed ovarian cancer cell growth and colony formation in vitro and inhibited ovarian cancer cell tumorigenesis in vivo. Further cell cycle and transcriptome profile analysis revealed that silence of ADAR1 in ovarian cancer cells induced cell cycle arrest at G1/G0 stage. Mechanistically, loss of ADAR1 caused R-loop abnormal accumulation, thereby contributing to single stand DNA break and ATR pathway activation. Additionally, ADAR1 interacted with DHX9 to regulate R-loop complex formation, and A-to-I editing of nascent RNA repressed R-loop formation during co-transcriptional process. Together, our results identify a novel ADAR1/R-loop/ATR axis critical for ovarian cancer progression and a potential target for ovarian cancer therapy.

A minor review of microRNA-338 exploring the insights of its function in tumorigenesis.

MicroRNAs(miRNAs) are small non-coding RNAs which have a critical role in various biological processes via direct binding and post-transcriptionally regulating targeted genes expression. More than one-half of human genes were regulated by miRNAs and their aberrant expression was detected in various human diseases, including cancers. miRNA-338 is a new identified miRNA and increasing evidence show that miRNA-338 participates in the progression of lots of cancers, such as lung cancer, hepatocellular cancer, breast cancer, glioma, and so on. Although a range of targets and signaling pathways such as MACC1 and Wnt/ß-catenin signaling pathway were illustrated to be regulated by miRNA-338, which functions in tumor progression are still ambiguous and the underlying molecular mechanisms are also unclear. Herein, we reviewed the latest studies in miRNA-338 and summarized its roles in different type of human tumors, which might provide us new idea for further investigations and potential targeted therapy.

Chimeric antigen receptor-engineered natural killer cells for cancer immunotherapy.

Natural killer (NK) cells are a critical component of the innate immune system. Chimeric antigen receptors (CARs) re-direct NK cells toward tumor cells carrying corresponding antigens, creating major opportunities in the fight against cancer. CAR NK cells have the potential for use as universal CAR cells without the need for human leukocyte antigen matching or prior exposure to tumor-associated antigens. Exciting data from recent clinical trials have renewed interest in the field of cancer immunotherapy due to the potential of CAR NK cells in the production of "off-the-shelf" anti-cancer immunotherapeutic products. Here, we provide an up-to-date comprehensive overview of the recent advancements in key areas of CAR NK cell research and identify under-investigated research areas. We summarize improvements in CAR design and structure, advantages and disadvantages of using CAR NK cells as an alternative to CAR T cell therapy, and list sources to obtain NK cells. In addition, we provide a list of tumor-associated antigens targeted by CAR NK cells and detail challenges in expanding and transducing NK cells for CAR production. We additionally discuss barriers to effective treatment and suggest solutions to improve CAR NK cell function, proliferation, persistence, therapeutic effectiveness, and safety in solid and liquid tumors.

An oncolytic herpesvirus expressing E-cadherin improves survival in mouse models of glioblastoma.

The efficacy of oncolytic herpes simplex virus (oHSV) is limited by rapid viral clearance by innate immune effector cells and poor intratumoral viral spread. We combine two approaches to overcome these barriers: inhibition of natural killer (NK) cells and enhancement of intratumoral viral spread. We engineered an oHSV to express CDH1, encoding E-cadherin, an adherent molecule and a ligand for KLRG1, an inhibitory receptor expressed on NK cells. In vitro, infection with this engineered virus, named OV-CDH1, induced high surface E-cadherin expression on infected glioblastoma (GBM) cells, which typically lack endogenous E-cadherin. Ectopically expressed E-cadherin enhanced the spread of OV-CDH1 by facilitating cell-to-cell infection and viral entry and reduced viral clearance by selectively protecting OV-CDH1-infected cells from KLRG1+ NK cell killing. In vivo, OV-CDH1 treatment substantially prolonged the survival in GBM-bearing mouse models, primarily because of improved viral spread rather than inhibition of NK cell activity. Thus, virus-induced overexpression of E-cadherin may be a generalizable strategy for improving cancer virotherapy.

Regulation of Human Natural Killer Cell IFN-γ Production by MicroRNA-146a via Targeting the NF-κB Signaling Pathway.

Natural killer (NK) cells are one group of innate lymphocytes that are important for host defense against malignancy and viruses. MicroRNAs (miRNAs) play a critical role in regulating responses of immune cells including NK cells. Accumulating evidence suggests that miR-146a is involved in the regulation of immune responses. However, the mechanism by which miR-146a regulates NK cell function is largely unknown. In the current study, we found that miR-146a intrinsically regulated NK cell function. Forced overexpression of miR-146a decreased IFN-γ production, whereas downregulation of miR-146a by anti-miR-146a significantly enhanced IFN-γ production in the human NK-92 cell line and primary human NK cells upon stimulation with IL-12 or co-stimulation with IL-12 and IL-18. Mechanistically, miR-146a regulated IFN-γ production via NF-κB, as evidenced in NK-92 cells, by downregulation of NF-κB p65 phosphorylation when miR-146a was overexpressed but upregulation of NF-κB p65 phosphorylation when anti-miR-146a was overexpressed. miR-146a directly targeted IRAK1 and TRAF6, the upstream signaling components of the NF-κB signaling pathway. This direct targeting mechanism confirmed the above gain- and loss-of-function approaches. However, the potent IFN-γ-producing subset, CD56bright NK cells, expressed higher levels of miR-146a than the lesser IFN-γ-producing subset, CD56dim NK cells. We also observed that co-stimulation of IL-12 and IL-18 significantly increased miR-146a expression in bulk NK cells and in the CD56bright subset in a time-dependent manner, correlating with augmented IFN-γ production. These data suggest that miR-146a plays a negative role in IFN-γ production by human NK cells and this miRNA may be critical in preventing NK cells from being super activated and overproducing IFN-γ.

RBFox2 Binds Nascent RNA to Globally Regulate Polycomb Complex 2 Targeting in Mammalian Genomes.

Increasing evidence suggests that diverse RNA binding proteins (RBPs) interact with regulatory RNAs to regulate transcription. RBFox2 is a well-characterized pre-mRNA splicing regulator, but we now encounter an unexpected paradigm where depletion of this RBP induces widespread increase in nascent RNA production in diverse cell types. Chromatin immunoprecipitation sequencing (ChIP-seq) reveals extensive interaction of RBFox2 with chromatin in a nascent RNA-dependent manner. Bayesian network analysis connects RBFox2 to Polycomb complex 2 (PRC2) and H3K27me3, and biochemical experiments demonstrate the ability of RBFox2 to directly interact with PRC2. Strikingly, RBFox2 inactivation eradicates PRC2 targeting on the majority of bivalent gene promoters and leads to transcriptional de-repression. Together, these findings uncover a mechanism underlying the enigmatic association of PRC2 with numerous active genes, highlight the importance of gene body sequences to gauge transcriptional output, and suggest nascent RNAs as critical signals for transcriptional feedback control to maintain homeostatic gene expression in mammalian genomes.

Mechano growth factor E peptide regulates migration and differentiation of bone marrow mesenchymal stem cells.

IGF1Ec in humans or IGF1Eb in rodents (known as mechano growth factor (MGF)) has a unique E domain, and the C-terminal end of the E domain (MGF E peptide) plays important roles in proliferation, migration and differentiation of many cell types. Bone marrow mesenchymal stem cells (BMSCs) have multiple differentiation potentials and are considered as perfect seed cells for tissue repair. But the role of MGF E peptide on BMSCs is seldom investigated and the mechanism is still unclear. In this study, we investigated the effects of MGF E peptide on rat BMSCs (rBMSCs). Our results revealed that treatment with MGF E peptide had no effect on BMSC proliferation. However, both wound-healing and transwell assays indicated that MGF E peptide could significantly enhance rBMSCs migration ability. Further analysis indicated that MGF E peptide also reduced the expression levels of osteogenic genes, but increased the expression levels of adipogenic genes. Analysis of molecular mechanism showed that phosphorylation-Erk1/2 was activated by MGF E peptide and blockage of either Erk1/2 or IGF1 receptor could repress the migration effect of MGF E peptide. In conclusion, MGF E peptide is able to inhibit osteogenic differentiation but promote adipogenic differentiation. In addition, the migration effect of MGF E peptide on rBMSCs depends on IGF1 receptor via Erk1/2 signal pathway.

A siRNA system based on HSP70 promoter results in controllable and powerful gene silencing by heat-induction.

RNAi is a powerful tool for gene-specific knockdown and gene therapy. However, the imprecise expression of siRNA limits the extensive application of RNAi in gene therapy. Here we report the development of a novel controllable siRNA expression vector pMHSP70psil that is initiated by HSP70 promoter. We determined the efficiency of the controllable siRNA system by targeting the gama-synuclein (SNCG) gene in breast cancer cells MCF-7. The results show that the controllable siRNA system can be induced to initiate siRNA expression by heat-induction. The silencing effect of SNCG occurs at a relatively low level (10.1%) at 37°C, while it is significantly increased to 69.4% after heat induction at 43°C. The results also show that the controllable siRNA system inhibits proliferation of cancer cells by heat-shock. Therefore, this RNAi strategy holds the promise of the high efficiency in gene knockdown at targeted times and locations, avoiding systemic side effects. It provides, for the first time, an approach to control siRNA expression by heat-shock.

Stem cell lineage commitment by electrical fields and the potential application in drug discovery.

Stem cells may be applied to improve the efficiency of drug discovery, but more effective protocols are first required to control the differentiation. Recent researches have revealed that physical stimulation is an important avenue for stem cell lineage commitment, such as electrical field stimulation. Here, we review literatures about stem cell differentiation by electrical field stimulation. Various forms of electrical fields with soluble induction factors have shown to produce a synergistic effect in order to enhance the osteogenic commitment. Moreover, electrical field stimulation alone shows marked effects of pre-commitment to cardiomyocyte and neuron. However, the related precise molecular regulatory mechanism is unclear. As cardiomyocyte and neuron are crucial factors in drug development process, electrical field stimulation may be proposed as an effect important for stem cell differentiation, exhibiting a potential application in drug discovery.