BackgroundNon-coding RNAs (ncRNAs) have been shown to regulate gene expression involved in tumor progression of multiple malignancies. Our previous studies indicated that large tumor suppressor kinase 1 (LATS1), a core part of Hippo signaling pathway, functions as a tumor suppressor in gastric cancer (GC). But, the underlying molecular mechanisms by which ncRNAs modulate LATS1 expression in GC remain undetermined.MethodsThe correlation of LATS1 and has-miR-424-5p (miR-424) expression with clinicopathological characteristics and prognosis of GC patients was analyzed by TCGA RNA-sequencing data. A novel circular RNA_LARP4 (circLARP4) was identified to sponge miR-424 by circRNA expression profile and bioinformatic analysis. The binding site between miR-424 and LATS1 or circLARP4 was verified using dual luciferase assay and RNA immunoprecipitation (RIP) assay. The expression and localization of circLARP4 in GC tissues were investigated by fluorescence in situ hybridization (FISH). MTT, colony formation, Transwell and EdU assays were performed to assess the effects of miR-424 or circLARP4 on cell proliferation and invasion.ResultsIncreased miR-424 expression or decreased LATS1 expression was associated with pathological stage and unfavorable prognosis of GC patients. Ectopic expression of miR-424 promoted proliferation and invasion of GC cells by targeting LATS1 gene. Furthermore, circLARP4 was mainly localized in the cytoplasm and inhibited biological behaviors of GC cells by sponging miR-424. The expression of circLARP4 was downregulated in GC tissues and represented an independent prognostic factor for overall survival of GC patients.ConclusioncircLARP4 may act as a novel tumor suppressive factor and a potential biomarker in GC.Electronic supplementary materialThe online version of this article (10.1186/s12943-017-0719-3) contains supplementary material, which is available to authorized users.

b Dysbiosis in the intestinal microbiota of persons with inflammatory bowel disease (IBD) has been described, but there are still varied reports on changes in the abundance of Bifidobacterium and Lactobacillus organisms in patients with IBD. The aim of this investigation was to compare the compositions of mucosa-associated and fecal bacteria in patients with IBD and in healthy controls (HCs). Fecal and biopsy samples from 21 HCs, 21 and 15 Crohn's disease (CD) patients, and 34 and 29 ulcerative colitis (UC) patients, respectively, were analyzed by quantitative real-time PCR targeting the 16S rRNA gene. The bacterial numbers were transformed into relative percentages for statistical analysis. The proportions of bacteria were uniformly distributed along the colon regardless of the disease state. Bifidobacterium was significantly increased in the biopsy specimens of active UC patients compared to those in the HCs (4.6% versus 2.1%, P ‫؍‬ 0.001), and the proportion of Bifidobacterium was significantly higher in the biopsy specimens than in the fecal samples in active CD patients (2.7% versus 2.0%, P ‫؍‬ 0.012). The Lactobacillus group was significantly increased in the biopsy specimens of active CD patients compared to those in the HCs (3.4% versus 2.3%, P ‫؍‬ 0.036). Compared to the HCs, Faecalibacterium prausnitzii was sharply decreased in both the fecal and biopsy specimens of the active CD patients (0.3% versus 14.0%, P < 0.0001 for fecal samples; 0.8% versus 11.4%, P < 0.0001 for biopsy specimens) and the active UC patients (4.3% versus 14.0%, P ‫؍‬ 0.001 for fecal samples; 2.8% versus 11.4%, P < 0.0001 for biopsy specimens). In conclusion, Bifidobacterium and the Lactobacillus group were increased in active IBD patients and should be used more cautiously as probiotics during the active phase of IBD. Butyrate-producing bacteria might be important to gut homeostasis.

SummaryThe gastric pathogen Helicobacter pylori induces a strong inflammatory host response, yet the bacterium maintains long-term persistence in the host. H. pylori combats oxidative stress via a battery of diverse activities, some of which are unique or newly described. In addition to using the well-studied bacterial oxidative stress resistance enzymes superoxide dismutase and catalase, H. pylori depends on a family of peroxiredoxins (alkylhydroperoxide reductase, bacterioferritin co-migratory protein and a thiolperoxidase) that function to detoxify organic peroxides. Newly described antioxidant proteins include a soluble NADPH quinone reductase (MdaB) and an iron sequestering protein (NapA) that has dual roles -host inflammation stimulation and minimizing reactive oxygen species production within H. pylori. An H. pylori arginase attenuates host inflammation, a thioredoxin required as a reductant for many oxidative stress enzymes is also a chaperon, and some novel properties of KatA and AhpC were discovered. To repair oxidative DNA damage, H. pylori uses an endonuclease (Nth), DNA recombination pathways and a newly described type of bacterial MutS2 that specifically recognizes 8-oxoguanine. A methionine sulphoxide reductase (Msr) plays a role in reducing the overall oxidized protein content of the cell, although it specifically targets oxidized Met residues. H. pylori possess few stress regulator proteins, but the key roles of a ferric uptake regulator (Fur) and a post-transcriptional regulator CsrA in antioxidant protein expression are described. The roles of all of these antioxidant systems have been addressed by a targeted mutant analysis approach and almost all are shown to be important in host colonization. The described antioxidant systems in H. pylori are expected to be relevant to many bacterial-associated diseases, as genes for most of the enzymes carrying out the newly described roles are present in a number of pathogenic bacteria.

BackgroundPatients with gastric cancer commonly have a poor prognosis, owing to its invasiveness and distant metastasis. Recent studies have confirmed the pivotal role of long non-coding RNAs (lncRNAs) in tumorigenesis and the progression of malignant tumors, including gastric cancer. However, little is known about the molecular mechanism by which lncRNA AK023391 contributes to gastric cancer.MethodsA lncRNA microarray was used to identify the differentially expressed lncRNA AK023391 in gastric cancer and adjacent normal tissues. In addition, RNA fluorescence in situ hybridization (FISH) was used to investigate the association between AK023391 expression and the clinicopathological characteristics and prognosis of patients with gastric cancer. Subsequently, a series of in vitro assays and a xenograft tumor model were used to observe the functions of lncRNA AK023391 in gastric cancer cells. A cancer pathway microarray, bioinformatic analysis, western blotting, and immunochemistry were carried out to verify the regulation of AK023391 and its downstream PI3K/Akt signaling pathway.ResultsExpression of lncRNA AK023391 was significantly upregulated in gastric cancer samples and cell lines in comparison to adjacent normal tissues, and was positively correlated with poor survival in patients with gastric cancer. The multivariate Cox regression model revealed that AK023391 expression acted as an independent prognostic factor for survival in patients with gastric cancer. Knockdown of AK023391 inhibited cell growth and invasion both in vitro and in vivo, and induced apoptosis and cell cycle arrest in gastric cancer cells, whereas its overexpression reversed these effects. Mechanistically, PI3K/Akt signaling mediated the NF-κB, FOXO3a, and p53 pathways. Moreover, downstream transcription factors, such as c-myb, cyclinB1/G2, and BCL-6 might be involved in AK023391-induced tumorigenesis in gastric cancer.ConclusionsThe novel oncogenic lncRNA AK023391 in gastric cancer exerts its effects through activation of the PI3K/Akt signaling pathway, and may act as a potential biomarker for survival in patients with gastric cancer.Electronic supplementary materialThe online version of this article (10.1186/s13046-017-0666-2) contains supplementary material, which is available to authorized users.

Oxidative stress resistance is one of the key properties that enable pathogenic bacteria to survive the toxic reactive oxygen species released by the host. In a previous study characterizing oxidative stress resistance mutants of Helicobacter pylori, a novel potential antioxidant protein (MdaB) was identified by the observation that the expression of this protein was significantly upregulated to compensate for the loss of other major antioxidant components. In this study, we characterized an H. pylori mdaB mutant and the MdaB protein.While the wild-type strain can tolerate 10% oxygen for growth, the growth of the mdaB mutant was significantly inhibited by this oxygen condition. The mdaB mutant is also more sensitive to H 2 O 2 , organic hydroperoxides, and the superoxide-generating agent paraquat. Although the wild-type strain can survive more than 10 h of air exposure, exposure of the mutant strain to air for 8 h resulted in recovery of no viable cells. The oxidative stress sensitivity of the mdaB mutant resulted in a deficiency in the ability to colonize mouse stomachs. H. pylori was recovered from 10 of 11 mouse stomachs inoculated with the wild-type strain, with about 5,000 to 45,000 CFU/g of stomach. However, only 3 of 12 mice that were inoculated with the mdaB mutant strain were found to harbor any H. pylori, and these 3 contained less than 2,000 CFU/g of stomach. A His-tagged MdaB protein was purified and characterized. It was shown to be a flavoprotein that catalyzes two-electron transfer from NAD(P)H to quinones. It reduces both ubiquinones and menaquinones with similar efficiencies and preferably uses NADPH as an electron donor. We propose that the physiological function of the H. pylori MdaB protein is that of an NADPH quinone reductase that plays an important role in managing oxidative stress and contributes to successful colonization of the host.

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B-cell translocation gene 2 (BTG2), the first gene identified in the BTG/TOB gene family, is involved in many biological activities in cancer cells acting as a tumor suppressor. The BTG2 expression is downregulated in many human cancers. It is an instantaneous early response gene and plays important roles in cell differentiation, proliferation, DNA damage repair, and apoptosis in cancer cells. Moreover, BTG2 is regulated by many factors involving different signal pathways. However, the regulatory mechanism of BTG2 is largely unknown. Recently, the relationship between microRNAs and BTG2 has attracted much attention. MicroRNA-21 (miR-21) has been found to regulate BTG2 gene during carcinogenesis. In this review, we summarize the latest findings in the investigations of biological functions of BTG2 and regulation of its expression, with an emphasis on miR-21 in regulation of BTG2 gene in various cancers. B-cell translocation gene 2 (BTG2), also known as PC3 or TIS21, belongs to the antiproliferative (APRO) gene family. Several studies have demonstrated that BTG2 is involved in a large number of physiological and pathological processes, such as cell differentiation, proliferation, apoptosis, and other cellular functions, acting as a tumor suppressor. In this review, we summarize the latest findings in BTG2 studies, highlighting the mechanisms for the regulatory effects of microRNAs (miRNAs) on BTG2 gene expression in the most common human cancers.

SummaryThe human gastric pathogenic bacterium Helicobacter pylori lacks a MutSLH-like DNA mismatch repair system. Here, we have investigated the functional roles of a mutS homologue found in H. pylori , and show that it plays an important physiological role in repairing oxidative DNA damage.