Silencing of acetyl-CoA carboxylase-α gene in human gastric cancer cells inhibits proliferation via induction of apoptosis, autophagy and suppression of cell invasion

Purpose: To study the role and therapeutic potential of acetyl-CoA-carboxylase-α (ACC) in the management of gastric cancer. Methods: Expression of ACC in gastric cancer cell lines was determined using quantitative real-time polymerase chain reaction (qRT-PCR). Lipofectamine 2000 reagent was used for transfection, while cell viability was determined by MTT assay. Apoptotic cell death was assayed with 4′, 6-diamidino-2- phenylindole (DAPI) and acridine orange/ethidium bromide (AO/EB) staining. The proportion of apoptotic cells was estimated with Annexin V/PI staining. Wound healing and Transwell assays were employed to monitor cell migration and invasion, while protein expression was determined using western blotting. Results: The results showed that ACC was significantly enhanced in SNU-1 gastric cancer cells (4.2- fold). Silencing of ACC in SNU-1 gastric cancer cells caused significant decrease in cell proliferation (p < 0.05). Electron microscopy examination showed that ACC silencing triggered autophagic cell death in SNU-1 cells, and increased expression of LC3 II. Results from DAPI and AO/EB assays demonstrated that ACC silencing also promoted apoptosis in SNU-1 gastric cancer cells. Annexin V/PI assay results revealed that apoptotic cell population increased from 2.7 to 13.8 % due to ACC silencing (p < 0.05). Moreover, Bax expression increased, while Bcl-2 expression decreased upon ACC silencing. Transwell assay results indicate that ACC silencing caused marked decrease in the invasion of the SNU-1 cells and downregulation of the expressions of MMP-2 and MMP-9 (p < 0.05). Conclusion: ACC is likely to be an important therapeutic target for gastric cancer

MicroRNA-31 induced by Fusobacterium nucleatum infection promotes colorectal cancer tumorigenesis

Summary: Persistent Fusobacterium nucleatum infection is associated with the development of human colorectal cancer (CRC) and promotes tumorigenicity, but the underlying mechanisms remain unclear. Here, we reported that F. nucleatum promoted the tumorigenicity of CRC, which was associated with F. nucleatum-induced microRNA-31 (miR-31) expression in CRC tissues and cells. F. nucleatum infection inhibited autophagic flux by miR-31 through inhibiting syntaxin-12 (STX12) and was associated with the increased intracellular survival of F. nucleatum. Overexpression of miR-31 in CRC cells promoted their tumorigenicity by targeting eukaryotic initiation factor 4F-binding protein 1/2 (eIF4EBP1/2), whereas miR-31 knockout mice were resistant to the formation of colorectal tumors. In conclusion, F. nucleatum, miR-31, and STX12 form a closed loop in the autophagy pathway, and continuous F. nucleatum-induced miR-31 expression promotes the tumorigenicity of CRC cells by targeting eIF4EBP1/2. These findings reveal miR-31 as a potential diagnostic biomarker and therapeutic target in CRC patients with F. nucleatum infection

A Bat-Derived Putative Cross-Family Recombinant Coronavirus with a Reovirus Gene

The emergence of severe acute respiratory syndrome coronavirus (SARS-CoV) in 2002 and Middle East respiratory syndrome coronavirus (MERS-CoV) in 2012 has generated enormous interest in the biodiversity, genomics and cross-species transmission potential of coronaviruses, especially those from bats, the second most speciose order of mammals. Herein, we identified a novel coronavirus, provisionally designated Rousettus bat coronavirus GCCDC1 (Ro-BatCoV GCCDC1), in the rectal swab samples of Rousettus leschenaulti bats by using pan-coronavirus RT-PCR and next-generation sequencing. Although the virus is similar to Rousettus bat coronavirus HKU9 (Ro-BatCoV HKU9) in genome characteristics, it is sufficiently distinct to be classified as a new species according to the criteria defined by the International Committee of Taxonomy of Viruses (ICTV). More striking was that Ro-BatCoV GCCDC1 contained a unique gene integrated into the 3’-end of the genome that has no homologs in any known coronavirus, but which sequence and phylogeny analyses indicated most likely originated from the p10 gene of a bat orthoreovirus. Subgenomic mRNA and cellular-level observations demonstrated that the p10 gene is functional and induces the formation of cell syncytia. Therefore, here we report a putative heterologous inter-family recombination event between a single-stranded, positive-sense RNA virus and a double-stranded segmented RNA virus, providing insights into the fundamental mechanisms of viral evolution

A Bat-Derived Putative Cross-Family Recombinant Coronavirus with a Reovirus Gene

The emergence of severe acute respiratory syndrome coronavirus (SARS-CoV) in 2002 and Middle East respiratory syndrome coronavirus (MERS-CoV) in 2012 has generated enormous interest in the biodiversity, genomics and cross-species transmission potential of coronaviruses, especially those from bats, the second most speciose order of mammals. Herein, we identified a novel coronavirus, provisionally designated Rousettus bat coronavirus GCCDC1 (Ro-BatCoV GCCDC1), in the rectal swab samples of Rousettus leschenaulti bats by using pan-coronavirus RT-PCR and next-generation sequencing. Although the virus is similar to Rousettus bat coronavirus HKU9 (Ro-BatCoV HKU9) in genome characteristics, it is sufficiently distinct to be classified as a new species according to the criteria defined by the International Committee of Taxonomy of Viruses (ICTV). More striking was that Ro-BatCoV GCCDC1 contained a unique gene integrated into the 3’-end of the genome that has no homologs in any known coronavirus, but which sequence and phylogeny analyses indicated most likely originated from the p10 gene of a bat orthoreovirus. Subgenomic mRNA and cellular-level observations demonstrated that the p10 gene is functional and induces the formation of cell syncytia. Therefore, here we report a putative heterologous inter-family recombination event between a single-stranded, positive-sense RNA virus and a double-stranded segmented RNA virus, providing insights into the fundamental mechanisms of viral evolution

Syncytium formation and functional analyses of Ro-BatCoV GCCDC1 p10 gene.

<p>(A) The construction of transient expression plasmid of p10 gene based on a pCAGGS vector. (B) Transient expression of the p10 gene and syncytium formation. <b>Top:</b> the observation of syncytium formation with Wright-Giemsa staining on the monolayer BHK-21 cells transfected with recombinant plasmid of Pulau virus p10 gene, recombinant plasmid of Ro-BatCoV GCCDC1 p10 gene, and empty pCAGGS vector; <b>Bottom:</b> the observation of syncytium formation with indirect immunofluorescence staining on the cells treated as described above. (C) The construction of subgenomic plasmid of p10 gene. The putative subgenome of p10 was cloned into a pcDNA3.0-derived vector. (D) Transient expression of the p10 gene and syncytium formation with recombinant subgenomic p10 plasmid. <b>Top:</b> the observation of syncytium formation with Wright-Giemsa staining on the monolayer BHK-21 cells transfected with recombinant plasmid of Pulau virus p10 gene, recombinant plasmid of p10 subgenome of Ro-BatCoV GCCDC1 and empty pcDNA3.0 vector; <b>Bottom:</b> the observation of syncytium formation with indirect immunofluorescence staining on the cells treated as described above. (Wright-Giemsa staining: stained monolayers were imaged using an Olympus IX51FL+DP70 microscope under 100× magnification, scale bars = 200 μm; indirect immunofluorescence staining: stained monolayers were imaged using a Nikon DIAPHOT-TMD microscope under 200× magnification, scale bars = 50 μm).</p

Identification of the recombinant p10 gene and its TRS.

<p>(A) Confirmation of the “exotic” p10 gene. The sequences that cover the upstream junction site between the N and p10 genes, and downstream junction site between the p10 and NS7a genes, are illustrated with sequencing patterns. The length of the intergenic sequence between the N and p10 genes is indicated with a number. The TRS preceding the NS7a gene in the intergenic sequence is marked with red arrow. (B) Identification of the TRS of the p10 gene. The TRS of the p10 gene in the N gene is illustrated with a sequencing pattern. The distance from the TRS to the AUG codon of p10 gene is indicated with a number. The length of the intergenic sequence between the N gene and genes just downstream of N gene are indicated with numbers. The TRSs of genes just downstream of N gene are marked with red arrows.</p

Prediction of the putative pp1a/pp1ab cleavage sites of Ro-BatCoV GCCDC1 based on comparison with prototype coronaviruses^a.

<p>Prediction of the putative pp1a/pp1ab cleavage sites of Ro-BatCoV GCCDC1 based on comparison with prototype coronaviruses<a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1005883#t002fn001" target="_blank">^a</a>.</p

Comparison of the 3'-terminus of the N gene of Ro-BatCoV GCCDC1 with those of Ro-BatCoV HKU9 strains and Ro-BatCoV Kenya.

<p>Alignment of nucleotide and amino acid sequence of the 3'-terminus of the N gene among Ro-BatCoV GCCDC1, Ro-BatCoV HKU9 strains and Ro-BatCoV Kenya. The eight amino acid truncation and two-amino-acid deletion at the 3’-terminus of N protein of the Ro-BatCoV GCCDC1 are illustrated.</p