Background Globally, gastric cancer (GC) is the third most common source of cancer-associated mortality. The aim of this study was to identify key genes and circular RNAs (circRNAs) in GC diagnosis, prognosis, and therapy and to further explore the potential molecular mechanisms of GC. Material/Methods Differentially expressed genes (DEGs) and circRNAs (DE circRNAs) between GC tissues and adjacent non-tumor tissues were identified from 3 mRNA and 3 circRNA expression profiles. Functional analyses were performed, and protein–protein interaction (PPI) networks were constructed. The significant modules and key genes in the PPI networks were identified. Kaplan-Meier analysis was performed to evaluate the prognostic value of these key genes. Potential miRNA-binding sites of the DE circRNAs and target genes of these miRNAs were predicted and used to construct DE circRNA–miRNA–mRNA networks. Results A total of 196 upregulated and 311 downregulated genes were identified in GC. The results of functional analysis showed that these DEGs were significantly enriched in a variety of functions and pathways, including extracellular matrix-related pathways. Ten hub genes ( COL1A1, COL3A1, COL1A2, COL5A2, FN1, THBS1, COL5A1, SPARC, COL18A1, and COL11A1 ) were identified via PPI network analysis. Kaplan-Meier analysis revealed that 7 of these were associated with a poor overall survival in GC patients. Furthermore, we identified 2 DE circRNAs, hsa_circ_0000332 and hsa_circ_0021087. To reveal the potential molecular mechanisms of circRNAs in GC, DE circRNA–microRNA–mRNA networks were constructed. Conclusions Key candidate genes and circRNAs were identified, and novel PPI and circRNA–microRNA–mRNA networks in GC were constructed. These may provide useful information for the exploration of potential biomarkers and targets for the diagnosis, prognosis, and therapy of GC.

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The Tembusu virus (TMUV) PS strain, derived by several passages and plaque purifications in BHK-21 cells, displays remarkedly lower virulence in Pekin ducklings relative to a natural isolate of TMUV, but the potential virulence determinants and the in vivo mechanisms for substantial virulence attenuation of the passage variant remain unknown. Here, we constructed a series of chimeric and mutant viruses and assessed their virulence using a 2-day-old Pekin duckling model. We showed that residue 304 in the envelope (E) protein is the molecular determinant of TMUV virulence. Further investigations with mutant and parental viruses demonstrated that acquisition of positive charges at E protein residue 304 plays a critical role in substantial attenuation of neurovirulence and neuroinvasiveness, which is linked to enhanced binding affinity for glycosaminoglycans (GAG). In Pekin ducklings infected by subcutaneous inoculation, an Arg at residue 304 in the E protein was shown to contribute to more rapid virus clearance from the circulation, remarkedly reduced viremia, and significantly decreased viral growth in the extraneural tissues and the central neural system, relative to a Met at the corresponding residue. These findings suggest that in vivo mechanism of virulence attenuation of the TMUV passage variant closely resembles that proposed previously for GAG-binding variants of other flaviviruses. Overall, our study provides insight into the molecular basis of TMUV virulence and the in vivo consequences of acquisition of a GAG-binding determinant at residue 304 in the E protein of TMUV.IMPORTANCE TMUV related disease emerged in 2010 has a significant economic impact on the duck industry. Although the disease was originally recognized to affect adult ducks, increasing evidences have shown that TMUV also causes severe disease of young ducklings. It is, therefore, essential to investigate the pathogenesis of TMUV infection in a young duckling model. The significance of our studies is in identifying E protein residue Arg304 as the molecular determinant for TMUV virulence and in clarifying the crucial role of positive charges at E protein residue 304 in virulence attenuation of TMUV passage variant. These data will greatly enhance our understanding of the pathogenesis of TMUV infection in ducklings, and have implications for development of a safe and efficient vaccine.

TMEM16A, a calcium-activated chloride channel (CaCC), is highly amplified and expressed in human cancers and is involved in the growth and metastasis of some malignancies. Inhibition of TMEM16A represents a novel pharmaceutical approach for the treatment of cancers and metastases. The purpose of this study is to identify a new TMEM16A inhibitor, investigate the effects of this inhibitor on the proliferation and metastasis of TMEM16A-amplified SW620 cells, and to elucidate the underlying molecular mechanism in vitro. We identified a novel small-molecule TMEM16A inhibitor dehydroandrographolide (DP). By using patch clamp electrophysiology, we showed that DP inhibited TMEM16A chloride currents in Fisher rat thyroid (FRT) cells that were transfected stably with human TMEM16A and in TMEM16A-overexpressed SW620 cells but did not alter cystic fibrosis transmembrane conductance regulator (CFTR) chloride currents. Further functional studies showed that DP suppressed the proliferation of SW620 cells in a dose- and time-dependent manner using MTT assays. Moreover, DP significantly inhibited migration and invasion of SW620 cells as detected by wound-healing and transwell assays. Further mechanistic study demonstrated that knockdown of human TMEM16A decreased the inhibitory effect of DP on the proliferation of SW620 cells and that TMEM16A-dependent cells (SW620 and HCT116) were more sensitive to DP than TMEM16A-independent cells (SW480 and HCT8). In addition, we found that treatment of SW620 cells with DP led to a decrease in TMEM16A protein levels but had no effect on TMEM16A mRNA levels. The current work reveals that DP, a novel TMEM16A inhibitor, exerts its anticancer activity on SW620 cells partly through a TMEM16A-dependent mechanism, which may introduce a new targeting approach for an antitumour therapy in TMEM16A-amplified cancers.