Enantioselective Ir-Catalyzed Allyl Alkylation/Semipinacol Rearrangement.

The semipinacol rearrangement is a powerful and versatile method for constructing all-carbon quaternary stereocenters. The development of catalytic asymmetric semipinacol rearrangements using multifunctionalizable electrophiles remains highly sought-after in organic synthesis. In this study, a catalytic enantioselective allylic cation-induced semipinacol rearrangement reaction was presented that enables the simultaneous construction of two skipped chiral carbon centers. Chiral Ir(I)-(P,olefin) and Sc(OTf)3 catalysts cooperatively initiate the asymmetric allylic alkylation of alkenyl cyclobutanols with allylic alcohols, triggering ring expansion of the cyclobutanol moiety through a stereoselective 1,2-alkyl migration. The reaction afforded a range of cyclopentanones bearing an α-quaternary carbon that is adjacent to a chiral allyl scaffold. The products were applied to synthesize enantioenriched fused tricyclopentanoids bearing four stereogenic carbon centers.

Epstein-Barr Virus Synergizes with BRD7 to Conquer c-Myc-Mediated Viral Latency Maintenance via Chromatin Remodeling.

Epstein-Barr virus (EBV) switches between latent and lytic phases in hosts, which is important in the development of related diseases. However, the underlying mechanism of controlling the viral biphasic life cycle and how EBV mediates this regulation remain largely unknown. This study identified bromodomain-containing protein 7 (BRD7) as a crucial host protein in EBV latent infection. Based on the chromatin immunoprecipitation (ChIP) sequencing of endogenous BRD7 in Burkitt lymphoma cells, we found that EBV drove BRD7 to regulate cellular and viral genomic loci, including the transcriptional activation of c-Myc, a recently reported regulator of EBV latency. Additionally, EBV-mediated BRD7 signals were enriched around the FUSE (far-upstream sequence element) site in chromosome 8 and the enhancer LOC108348026 in the lgH locus, which might activate the c-Myc alleles. Mechanically, EBV-encoded nuclear antigen 1 (EBNA1) bound to BRD7 and colocalized at promoter regions of the related genes, thus serving as cofactors for the maintenance of viral latency. Moreover, the disruption of BRD7 decreased the c-Myc expression, induced the BZLF1 expression, and reactivated the lytic cycle. Our findings reveal the unique role of BRD7 to synergize with EBV in maintaining the viral latency state via chromatin remodeling. This study paves the way for understanding the new molecular mechanism of EBV-induced chromatin remodeling and latent-lytic switch, providing novel therapeutic candidate targets for EBV persistent infection. IMPORTANCE When establishing persistent infection in most human hosts, EBV is usually latent. How the viral latency is maintained in cells remains largely unknown. c-Myc was recently reported to act as a controller of the lytic switch, while whether and how EBV regulates it remain to be explored. Here, we identified that BRD7 is involved in controlling EBV latency. We found that EBV-mediated BRD7 was enriched in both the normal promoter regions and the translocation alleles of c-Myc, and disruption of BRD7 decreased c-Myc expression to reactivate the lytic cycle. We also demonstrated that EBV-encoded EBNA1 bound to and regulated BRD7. Therefore, we reveal a novel mechanism by which EBV can regulate its infection state by coordinating with host BRD7 to target c-Myc. Our findings will help future therapeutic intervention strategies for EBV infection and pathogenesis.

The four­microRNA signature identified by bioinformatics analysis predicts the prognosis of nasopharyngeal carcinoma patients.

The aim of the present study was to identify microRNAs (miRNAs) that predict the prognosis of patients with nasopharyngeal carcinoma by integrated bioinformatics analysis. First, the original microarray dataset GSE32960, including 312 nasopharyngeal carcinomas and 18 normal samples, was downloaded from the Gene Expression Omnibus database. In addition, 46 differentially expressed miRNAs (DEMs) were screened. Then, four miRNAs, including hsa­miR­142­3p, hsa­miR­150, hsa­miR­29b, and hsa­miR­29c, were obtained as prognostic markers by combining univariate Cox regression analysis with weighted gene coexpression network analysis (WGCNA). Subsequently, the risk score of 312 NPC patients from the signature of miRNAs was calculated, and patients were divided into high­risk or low­risk groups. Notably, compared with patients with low­risk scores, high­risk groups had shorter disease­free survival (DFS), overall survival (OS), and distant metastasis­free survival (DMFS). Receiver operating characteristic curve (ROC) analysis indicated that the risk score was a very effective prognostic factor. Moreover, the Search Tool for the Database for Annotation, Visualization, and Integrated Discovery (DAVID), Cytoscape, starBase, and Retrieval of Interacting Genes database (STRING) were used to establish the miRNA­mRNA correlation network and the protein­protein interaction (PPI) network. In addition, the shared genes superimposing 888 protein­coding genes targeted by four hub miRNAs and 1,601 upregulated differentially expressed mRNAs accounted for 127 and were used for subsequent gene functional enrichment analysis. In particular, biological pathway analysis indicated that these genes mainly participate in some vital pathways related to cancer pathogenesis, such as the focal adhesion, PI3K/Akt, p53, and mTOR signalling pathways. In summary, the identification of NPC patients with a four­miRNA signature may increase the prognostic value and provide reference information for precision medicine.

Differential expression profiling of lncRNAs related to Epstein-Barr virus infection in the epithelial cells.

Epstein-Barr virus (EBV) is a prevalent γ-herpesvirus associated with a variety of cancers, including epithelial nasopharyngeal carcinoma (NPC) and gastric carcinoma (GC). Long noncoding RNAs (lncRNAs) are emerging as powerful regulators that have demonstrated to play crucial roles in cancer development. In this approach, based on genome-wide RNA sequencing, we examined the lncRNA expression profiles in four EBV genome-infected and EBV-negative 293 cells. A series of lncRNAs were found to be dysregulated in a comparative analysis. Then, eight typical lncRNAs were selected for validation of expression levels by real-time quantitative polymerase chain reaction and were detected in EBV-positive or EBV-negative GC and NPC cells. The differential expression patterns of the eight lncRNAs for validation were fundamentally identical to those revealed in RNA sequencing. Particularly, the differential expression of these lncRNAs in GC and NPC cells indicated their possible roles in EBV infection and tumorigenesis. In addition, a predicted lncRNA-microRNA-messenger RNA network suggested their potential interactions. This study reveals the first lncRNAome related to EBV infection in the epithelial cells and provides novel clues for the study of viral role in epithelial cancers through the interaction between EBV and host lncRNAs.

Early Pattern of Epstein-Barr Virus Infection in Gastric Epithelial Cells by "Cell-in-cell".

Epstein-Barr virus (EBV) is an important human dsDNA virus, which has been shown to be associated with several malignancies including about 10% of gastric carcinomas. How EBV enters an epithelial cell has been an interesting project for investigation. "Cell-in-cell" infection was recently reported an efficient way for the entry of EBV into nasopharynx epithelial cells. The present approach was to explore the feasibility of this mode for EBV infection in gastric epithelial cells and the dynamic change of host inflammatory reaction. The EBV-positive lymphoblastic cells of Akata containing a GFP tag in the viral genome were co-cultured with the gastric epithelial cells (GES-1). The infection situation was observed under fluorescence and electron microscopies. Real-time quantitative PCR and Western-blotting assay were employed to detect the expression of a few specific cytokines and inflammatory factors. The results demonstrated that EBV could get into gastric epithelial cells by "cell-in-cell" infection but not fully successful due to the host fighting. IL-1ß, IL-6 and IL-8 played prominent roles in the cellular response to the infection. The activation of NF-κB and HSP70 was also required for the host antiviral response. The results imply that the gastric epithelial cells could powerfully resist the virus invader via cell-in-cell at the early stage through inflammatory and innate immune responses.

The role of exosomal noncoding RNAs in cancer.

Extracellular vesicles (EVs) membranes enclose nanosized vesicles with a size range of 30-150 nm and are plentiful in our body in both physiological and pathological conditions. Exosomes, a type of EV, are important mediators of intracellular communication among tumor cells, immune cells, and stromal cells. They can shuttle bioactive molecules, such as proteins, lipids, RNA, and DNA; however, the precise function of EVs remains largely unknown. In recent years, tumor-associated cargo in exosomes has been a hot topic in research, especially with respect to noncoding RNAs (ncRNAs). Herein, we review the role of exosomal ncRNAs, including miRNAs and long noncoding RNAs, in tumor biological processes. Clinically, exosomal ncRNAs may eventually become novel biomarkers and therapeutic targets in cancer progression.

Epstein-Barr Virus Nuclear Antigen 1 Recruits Cyclophilin A to Facilitate the Replication of Viral DNA Genome.

Epstein-Barr virus (EBV) nuclear antigen 1 (EBNA1)-mediated DNA episomal genome replication and persistence are essential for the viral pathogenesis. Cyclophilin A (CYPA) is upregulated in EBV-associated nasopharyngeal carcinoma (NPC) with unknown roles. In the present approach, cytosolic CYPA was found to be bound with EBNA1 into the nucleus. The amino acid 376-459 of the EBNA1 domain was important for the binding. CYPA depletion attenuated and ectopic CYPA expression improved EBNA1 expression in EBV-positive cells. The loss of viral copy number was also accelerated by CYPA consumption in daughter cells during culture passages. Mechanistically, CYPA mediated the connection of EBNA1 with oriP (origin of EBV DNA replication) and subsequent oriP transcription, which is a key step for the initiation of EBV genome replication. Moreover, CYPA overexpression markedly antagonized the connection of EBNA1 to Ubiquitin-specific protease 7 (USP7), which is a strong host barrier with a role of inhibiting EBV genome replication. The PPIase activity of CYPA was required for the promotion of oriP transcription and antagonism with USP7. The results revealed a strategy that EBV recruited a host factor to counteract the host defense, thus facilitating its own latent genome replication. This study provides a new insight into EBV pathogenesis and potential virus-targeted therapeutics in EBV-associated NPC, in which CYPA is upregulated at all stages.