The emergence and spread of COVID-19 since December, 2019, has brought great challenges to global public health. As of April 23, 2020, more than 2•5 million confirmed cases and more than 175 000 deaths had been reported globally. 1 Respiratory tract manifestations such as fever and cough are the most commonly reported symptoms in patients with COVID-19. 2 Evidence of digestive system involvement in patients with COVID-19 was first reported by a group in China. 3 Emerging data showed that the gastrointestinal tract and liver might also represent target organs of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on the basis of the findings that angiotensin-converting enzyme 2 (ACE2), the major receptor of SARS-CoV-2, is expressed in the gastro intestinal tract as well as liver cells. 4 The detection of SARS-CoV-2 viral RNA in patients' stool and the potential for faecal-oral transmission has raised

Small, noncoding RNA molecules, called microRNAs (miRNAs), are thought to function as either tumor suppressors or oncogenes. Common single-nucleotide polymorphisms (SNPs) in miRNAs may change their property through altering miRNA expression and/or maturation, and thus they may have an effect on thousands of target mRNAs, resulting in diverse functional consequences. However, it remains largely unknown whether miRNA SNPs may alter cancer susceptibility. We evaluated the associations of selected four SNPs (rs2910164, rs2292832, rs11614913, and rs3746444) in pre-miRNAs (hsa-mir-146a, hsa-mir-149, hsa-mir-196a2, and hsa-mir-499) with breast cancer risk in a case-control study of 1,009 breast cancer cases and 1,093 cancer-free controls in a population of Chinese women and we found that hsa-mir-196a2 rs11614913:T>C and hsa-mir-499 rs3746444:A>G variant genotypes were associated with significantly increased risks of breast cancer (odds ratio [OR], 1.23; 95% confidence interval [CI], 1.02-1.48 for rs11614913:T>C; and OR, 1.25; 95% CI, 1.02-1.51 for rs3746444:A>G in a dominant genetic model) in a dose-effect manner (P for trend was 0.010 and 0.037, respectively). These findings suggest, for the first time, that common SNPs in miRNAs may contribute to breast cancer susceptibility. Further functional characterization of miRNA SNPs and their influences on target mRNAs may provide underlying mechanisms for the observed associations and disease etiology.

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microRNAs (miRNA) are a new class of non-proteincoding, small RNAs that function as tumor suppressors or oncogenes. They participate in diverse biological pathways and function as gene regulators. Recently, we conducted a survey of common single nucleotide polymorphisms (SNP) in miRNA sequences and reported that, among four SNPs (rs2910164, rs2292832, rs11614913, and rs3746444) in pre-miRNAs, rs11614913 in miR-196a2 might affect mature miR-196a expression and target mRNA-binding activity and was significantly associated with non-small cell lung cancer survival. However, it remains largely unknown whether miRNA SNPs may alter lung cancer susceptibility. In the current study, we evaluated associations between the above four SNPs in pre-miRNAs and lung cancer susceptibility in a case-control study of 1,058 incident lung cancer patients and 1,035 cancer-free controls in a Chinese population. We found that miR-196a2 rs11614913 variant homozygote CC was associated with f25% significantly increased risk of lung cancer compared with their wild-type homozygote TT and heterozygote TC (odds ratio, 1.25; 95% confidence interval, 1.01-1.54). However, no significant effects were observed on the association between the other three SNPs and lung cancer risk. These findings suggest that functional SNP rs11614913 in miR-196a2 could also contribute to lung cancer susceptibility.

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Recent three genome-wide association studies have mapped a lung cancer susceptibility locus to chromosome 15q25 in Caucasians. However, the reported risk single nucleotide polymorphisms (SNPs) are extremely rare in Asians, arguing against any of these being causative variants. This study sought to identify other variants on 15q25 associated with lung cancer susceptibility in Chinese. Two-stage case-control studies were conducted in subjects derived from both Northern and Southern China. The first-stage, consisting of 576 cases and 576 controls, was to discover novel risk variants using a haplotype-tagging SNP approach, and these variants were then replicated in the second-stage, consisting of 2,989 cases and 2,880 controls. Associations were estimated by logistic regression models, and function of the variants was examined by biochemical assays. We found that the three risk SNPs reported in Caucasians were not associated with lung cancer risk in Chinese. However, we identified four novel SNPs (rs2036534C>T, rs667282C>T, rs12910984G>A, and rs6495309T>C) that were associated with significantly increased lung cancer risk and smoking behavior, which were all confirmed in the replication analyses [odds ratios (95% confidence intervals) in the dominant model: 1.39 (1.23-1.57; P = 2.3 × 10

Cellular prion protein (PrPc) is a glycosylphosphatidylinositol (GPI) -anchored membrane protein that is highly conserved in mammalian species. PrPc has the characteristics of adhesive molecules and is thought to play a role in cell adhesion and membrane signaling. Here we investigated the possible role of PrPc in the process of invasiveness and metastasis in gastric cancers. PrPc was found to be highly expressed in metastatic gastric cancers compared to nonmetastatic ones by immunohistochemical staining. PrPc significantly promoted the adhesive, invasive, and in vivo metastatic abilities of gastric cancer cell lines SGC7901 and MKN45. PrPc also increased promoter activity and the expression of MMP11 by activating phosphorylated ErK1/2 in gastric cancer cells. MEK inhibitor PD98059 and MMP11 antibody (Ab) significantly inhibited in vitro invasive and in vivo metastatic abilities induced by PrPc. N-terminal fragment (amino acid 24-90) was suggested to be an indispensable region for signal transduction and invasion-promoting function of PrPc. Taken together, the present work revealed a novel function of PrPc that the existence of N-terminal region of PrPc could promote the invasive and metastatic abilities of gastric cancer cells at least partially through activation of MEK/ERK pathway and consequent transactivation of MMP11.

SUMMARY BackgroundThere has been growing interest in the use of faecal microbiota transplantation (FMT) for the treatment of gastrointestinal and nongastrointestinal diseases.