Aberrant methylation of microRNA-34b/c is a predictive marker of metachronous gastric cancer risk

Microarchitectures of Barrett's esophagus associated with DNA methylation status

Aim: DNA methylation is involved in esophageal adenocarcinoma (EAC) and Barrett's esophagus (BE). Microarchitectures of on-neoplastic BE associated with DNA methylation status were examined using magnifying narrow-band imaging (NBI) endoscopy. Patients and methods: Using biopsies from non-neoplastic BE without cancer (n = 66; N group), with EAC (n = 27; ADJ group) and EAC tissue (n = 22; T group), methylation of N33, DPYS, SLC16A12, miR124a3 and miR34bc genes were quantified. Magnifying NBI features of non-neoplastic BE were classified according to their morphologies. Results: The ADJ and T groups presented higher DNA methylation compared with the N group. Magnifying NBI endoscopic features of non-neoplastic BE also correlated with DNA methylation as an independent factor. Conclusion: Microarchitectures of BE visualized by magnifying NBI endoscopy correlated with DNA methylation.

TM4SF1-AS1 inhibits apoptosis by promoting stress granule formation in cancer cells

Long noncoding RNAs (lncRNAs) play pivotal roles in tumor development. To identify dysregulated lncRNAs in gastric cancer (GC), we analyzed genome-wide trimethylation of histone H3 lysine 4 (H3K4me3) to screen for transcriptionally active lncRNA genes in the non-tumorous gastric mucosa of patients with GC and healthy individuals. We found that H3K4me3 at TM4SF1-AS1 was specifically upregulated in GC patients and that the expression of TM4SF1-AS1 was significantly elevated in primary and cultured GC cells. TM4SF1-AS1 contributes to GC cell growth in vitro and in vivo, and its oncogenic function is mediated, at least in part, through interactions with purine-rich element-binding protein α (Pur-α) and Y-box binding protein 1 (YB-1). TM4SF1-AS1 also activates interferon signaling in GC cells, which is dependent on Pur-α and RIG-I. Chromatin isolation by RNA purification (ChIRP)-mass spectrometry demonstrated that TM4SF1-AS1 was associated with several stress granule (SG)-related proteins, including G3BP2, RACK1, and DDX3. Notably, TM4SF1-AS1 promoted SG formation and inhibited apoptosis in GC cells by sequestering RACK1, an activator of the stress-responsive MAPK pathway, within SGs. TM4SF1-AS1-induced SG formation and apoptosis inhibition are dependent on Pur-α and YB-1. These findings suggested that TM4SF1-AS1 contributes to tumorigenesis by enhancing SG-mediated stress adaptation.

Dynamic variations of the gastric microbiota: Key therapeutic points in the reversal of Correa's cascade

Correa's cascade is a dynamic process in the development of intestinal-type gastric cancer (GC), and its pathological features, gastric microbiota and interactions between microorganisms and their hosts vary at different developmental stages. The characteristics of cells, tissues and gastric microbiota before or after key therapeutic points are critical for monitoring malignant transformation and early tumour reversal. This review summarises the pathological features of gastric mucosa, characteristics of gastric microbiota, specific microbial markers, microbe-microbe interactions and microbe-host interactions at different stages in Correa's cascade. The markers related to each Correa's cascade point were analysed in detail. We attempted to identify key therapeutic points for early cancer reversal and provide a novel approach to reduce the incidence of GC and improve precise treatment.

Long-term changes in aberrant DNA methylation and gastritis after Helicobacter pylori eradication focused on metachronous gastric cancer

BACKGROUND

A persistently high methylation level in gastric mucosa after Helicobacter pylori (H. pylori) eradication is presumed to be a risk for metachronous gastric cancer (MGC); however, long-term changes in aberrant DNA methylation and histological gastritis have been unclear. Our aim was to examine changes in DNA methylation and histological gastritis according to the occurrence of MGC.

METHODS

Subjects were classified into three groups: 25 patients in whom MGCs occurred after the initial endoscopic resection (ER) for early gastric cancer and H. pylori eradication (MGC group), 17 patients in whom MGC did not occur for more than 5 years after the initial ER and H. pylori eradication (non-MGC group) and 29 patients without a history of gastric cancer who succeeded in eradication more than 5 years ago (HP group). Aberrance of DNA methylation in three genes (miR-124a-3, EMX1, NKX6-1) and histological score of atrophy and intestinal metaplasia (IM) were evaluated using biopsy samples before and more than a mean of 5 years after H. pylori eradication. Also, the mean Z-score was calculated using Z-score values of the three genes.

RESULTS

The methylation level of miR-124a-3 in the HP group and non-MGC group and that of EMX1 in the HP group significantly decreased in the long term after eradication. In the MGC group, H. pylori eradication did not improve aberrant methylation, and the mean Z-score significantly increased. There were significant positive correlations between methylation levels in miR-124a-3 and EMX1 and histological findings after eradication.

CONCLUSIONS

A persistently high methylation level after H. pylori eradication reflected precancerous mucosal conditions and led to long-term MGC.

Gastric Xanthelasma, Microsatellite Instability and Methylation of Tumor Suppressor Genes in the Gastric Mucosa: Correlation and Comparison as a Predictive Marker for the Development of Synchronous/Metachronous Gastric Cancer

A predictive marker for the development of synchronous/metachronous gastric cancer (GC) would be highly desirable in order to establish an effective strategy for endoscopic surveillance. Herein, we examine the significance of gastric xanthelasma (GX) and molecular abnormalities for the prediction of synchronous/metachronous GC. Patients (n = 115) were followed up (range, 12–122; median, 55 months) in whom the presence of GX and molecular alterations, including microsatellite instability (MSI) and methylation of human mutL homolog 1 (hMLH1), cyclin-dependent kinase inhibitor 2A (CDKN2A) and adenomatous polyposis coli (APC) genes, had been confirmed in non-neoplastic gastric mucosa when undergoing endoscopic submucosal dissection (ESD) for early GC. At the start of surveillance, the numbers of positive subjects were as follows: GX, 59 (51.3%); MSI, 48 (41.7%); hMLH1, 37 (32.2%); CDKN2A, 7 (6.1%); APC, 18 (15.7%). After ESD treatment, synchronous/metachronous GCs occurred in patients with the following positive factors: GX, 16 (27.1%); MSI, 7 (14.6%); hMLH1, 6 (16.2%); CDKN2A, 3 (42.9%); APC, 3 (16.7%). The presence of GX had no significant relationship to positivity for MSI or methylation of hMLH1, CDKN2A or APC. GX was significantly (p = 0.0059) and independently (hazard ratio, 3.275; 95% confidence interval, 1.134–9.346) predictive for the development of synchronous/metachronous GC, whereas those genetic alterations were not predictive. GX is a simple and powerful marker for predicting the development of synchronous or metachronous GC.

Accurate diagnosis and prognosis prediction of gastric cancer using deep learning on digital pathological images: A retrospective multicentre study

Background

To reduce the high incidence and mortality of gastric cancer (GC), we aimed to develop deep learning-based models to assist in predicting the diagnosis and overall survival (OS) of GC patients using pathological images.

Methods

2333 hematoxylin and eosin-stained pathological pictures of 1037 GC patients were collected from two cohorts to develop our algorithms, Renmin Hospital of Wuhan University (RHWU) and the Cancer Genome Atlas (TCGA). Additionally, we gained 175 digital pictures of 91 GC patients from National Human Genetic Resources Sharing Service Platform (NHGRP), served as the independent external validation set. Two models were developed using artificial intelligence (AI), one named GastroMIL for diagnosing GC, and the other named MIL-GC for predicting outcome of GC.

Findings

The discriminatory power of GastroMIL achieved accuracy 0.920 in the external validation set, superior to that of the junior pathologist and comparable to that of expert pathologists. In the prognostic model, C-indices for survival prediction of internal and external validation sets were 0.671 and 0.657, respectively. Moreover, the risk score output by MIL-GC in the external validation set was proved to be a strong predictor of OS both in the univariate (HR = 2.414, P < 0.0001) and multivariable (HR = 1.803, P = 0.043) analyses. The predicting process is available at an online website (https://baigao.github.io/Pathologic-Prognostic-Analysis/).

Interpretation

Our study developed AI models and contributed to predicting precise diagnosis and prognosis of GC patients, which will offer assistance to choose appropriate treatment to improve the survival status of GC patients.

Funding

Not applicable.

Preventing Metachronous Gastric Cancer after the Endoscopic Resection of Gastric Epithelial Neoplasia: Roles of Helicobacter pylori Eradication and Aspirin

Whether Helicobacter pylori eradication actually reduces the risk of metachronous gastric cancer (MGC) development remains a controversial question. In this review, we addressed this topic by reviewing the results of clinical investigations and molecular pathological analyses of the roles of H. pylori eradication and aspirin administration in the prevention of MGC. In regard to the clinical studies, the results of meta-analyses and randomized control trials differ from those of retrospective studies: the former trials show that H. pylori eradication has a preventive effect on MGC, while the latter studies do not. This discrepancy may be at least partly attributable to differences in the follow-up periods: H. pylori eradication is more likely to prevent MGC over a long-term follow-up period (≥5 years) than over a short-term follow-up period. In addition, many studies have shown that aspirin may have an additive effect on MGC-risk reduction after H. pylori eradication has been achieved. Both H. pylori eradication and aspirin use induce molecular alterations in the atrophic gastritis mucosa but not in the intestinal metaplasia. Unfortunately, the molecular pathological analyses of these interventions have been limited by short follow-up periods. Therefore, a long-term prospective cohort is needed to clarify the changes in molecular events caused by these interventions.

Molecular alterations in gastric cancer and the surrounding intestinal metaplastic mucosa: an analysis of isolated glands

BACKGROUND

Intestinal metaplasias (IMs) are generally regarded as pre-neoplastic gastric lesions. However, molecular alterations including genetic and epigenetic changes occurring in individual IM glands are not well defined.

AIMS

We sought to identify DNA methylation status, microsatellite instability (MSI) and allelic imbalance (AI) occurring in individual IM glands and non-IM glands within the same mucosa.

METHODS

We divided examined isolated gland obtained from GC into 4 components: isolated cancer, antral isolated intestinal metaplastic tissue, antral isolated non-metaplastic gland and isolated non-metaplastic gland derived from the greater curvature of the most distant gastric body without mucosal atrophy. We examined AI and microsatellite instability statuses using PCR-based microsatellite analysis. Next, the DNA methylation status (high methylation epigenome [HME], intermediate methylation epigenome [IME], and low methylation epigenome [LME]) was investigated. DNA methylation analysis of CDKN2A, mir34-b/c and MLHI genes was also performed.

RESULTS

Although antral isolated IM glands were characterized by IME, isolated non-IM glands showed LME. In isolated cancer glands, HME was frequently found, compared with isolated non-IM glands. DNA methylation of mir34-b/c was common in isolated cancer and IM glands, whereas DNA methylation of CDKN2A was a rare event in isolated samples. The MLH1 gene was not methylated in isolated non-IM glands. Although multiple AIs were frequently found in isolated cancer glands, a few AIs were detected in isolated IM glands.

CONCLUSIONS

We suggest that the DNA methylation status and the status of the mir34-b/c gene among isolated samples of IMs and isolated non-IM glands have an impact on IM development.

Precision Medicine Approaches to Prevent Gastric Cancer

Gastric cancer remains one of the most common causes of cancer-related death worldwide, although the incidence is declining gradually. The primary risk factor for gastric cancer is Helicobacter pylori infection. The Kyoto global consensus report recommends eradication of H. pylori in all infected patients. However, because it is difficult to stratify the risk of carcinogenesis among patients with a history of H. pylori infection, annual endoscopic surveillance is performed for everyone after eradication. This review summarizes the current approaches used to screen for novel molecules that could assist in the diagnosis of gastric cancer and reduce mortality. Most well-studied molecules are tissue protein biomarkers expressed by the gastric epithelium and associated with metaplasia-dysplasia-carcinoma sequences. Other strategies focus on the origin of cancer stem cell-related markers, such as CD44, and immune reaction-related markers, such as matrix metallopeptidases. Noninvasive methods such as blood-based approaches are more attractive. Serum pepsinogen levels predict the severity of gastric mucosal atrophy before H. pylori eradication, whereas plasma ghrelin levels are associated with atrophy even after eradication. Cell-free DNAs and RNAs are attractive tools for the early detection of cancer. These ideas could lead to the development of more personalized strategies for cancer prevention based on cutting-edge technologies.

Non-Invasive Early Molecular Detection of Gastric Cancers

Gastric cancer (GC) is a significant source of global cancer death with a high mortality rate, because the majority of patients with GC are diagnosed at a late stage, with limited therapeutic choices and poor outcomes. Therefore, development of minimally invasive or noninvasive biomarkers which are specific to GC is crucially needed. The latest advancements in the understanding of GC molecular landscapes and molecular biological methods have accelerated attempts to diagnose GC at an early stage. Body fluids, including peripheral blood, saliva, gastric juice/wash, urine, and others, can be a source of biomarkers, offering new methods for the early detection of GC. Liquid biopsy-based methods using circulating sources of cancer nucleic acids could also be considered as alternative strategies. Moreover, investigating gastric juices/washes could represent an alternative for the detection of GC via invasive biopsy. This review summarizes recently reported biomarkers based on DNA methylation, microRNA, long noncoding RNA, circular RNA, or extracellular vesicles (exosomes) for the detection of GC. Although the majority of studies have been conducted to detect these alterations in advanced-stage GC and only a few in population studies or early-stage GC, some biomarkers are potentially valuable for the development of novel approaches for an early noninvasive detection of GC.

Dysregulated miRNA in a cancer-prone environment: A study of gastric non-neoplastic mucosa

Understanding cancer-prone environments is important to efficiently detect and prevent cancers. The associations between miRNA and cancer-prone environments are still largely unknown in gastric cancer (GC). Six miRNAs that are differentially expressed during gastric carcinogenesis were selected, and quantitative real-time PCR was performed in an independent training set (fresh non-tumor and tumor samples from 18 GC patients) and validation sets (set 1 with formalin-fixed paraffin-embedded non-tumor and tumor samples from 19 solitary GC and set 2 with 37 multiple GC patients). The results were compared with those of 37 gastric mucosa from 20 healthy volunteers. The expression levels of miR-26a, miR-375, and miR-1260 in gastric mucosa from healthy volunteers were statistically higher than that of non-tumorous gastric mucosa located 3 cm apart from the GC in the training set (miR-26a, P < 0.0001; miR-375, P = 0.0049; miR-1260, P = 0.0172), validation set 1 (miR-26a and miR-375, P < 0.0001; miR-1260, P = 0.0008), and validation set 2 (miR-26a, miR-375, and miR-1260, P < 0.0001). And a combination of miR-26a and miR-1260 showed the highest area under the curve value of 0.89. miRNAs are differentially expressed in non-neoplastic gastric mucosa and can be used as a biomarker to predict cancer-prone environments.

Gastric Mucosal Microarchitectures Associated with Irreversibility with Helicobacter pylori Eradication and Downregulation of Micro RNA (miR)-124a

To investigate the molecular mechanisms of gastric carcinogenesis after Helicobacter pylori (H. pylori) eradication, expression of miR-124a, miR-34b, and miR-34c was examined in nonneoplastic gastric specimens after successful H. pylori eradication. The magnifying narrow-band imaging (NBI) endoscopic features of gastric mucosa were also examined. The atrophic type, an informative endoscopic feature for histological intestinal metaplasia, showed lower expression of miR-124a. Lower expression of miR-124a correlated with hypermethylation of the miR-124a3 locus. The atrophic type represents gastric microarchitectures associated with irreversibility with H. pylori eradication and downregulation of miR-124a.

DNA methylation silencing of microRNA gene methylator in the precancerous background mucosa with and without gastric cancer: Analysis of the effects of H. pylori eradication and long-term aspirin use

The risk of gastric cancer (GC) declines after Helicobacter pylori (H. pylori) eradication and long-term aspirin use. We evaluated the effects of H. pylori eradication (Cohort 1) and aspirin use (Cohort 2) on the methylation of microRNAs (miRNAs), such as miR-34c, miR-124a-3, miR-129-2, and miR-137, in the gastric mucosa with and without GC, i.e., in atrophic mucosal glands without intestinal metaplasia (non-IM) and intestinal metaplastic glands (IM). DNA was isolated from non-IM and IM separately using laser caption microdissection. In Cohort 1, H. pylori eradication was associated with a significant reduction of miR-124a-3 methylation only in non-IM, but not in IM. miR-129-2 methylation in non-IM may be a surrogate marker of GC in H. pylori-infected patients. In Cohort 2, aspirin did not reverse miRNA methylation in either non-IM or IM, irrespective of H. pylori infection. miR-129-2 methylation in non-IM was an independent predictive marker of GC in H. pylori-infected but not -eradicated patients. These results indicate that H. pylori eradication and aspirin use were less effective for improving methylation in IM than in non-IM; thus, these interventions are recommended at an early stage prior to the development of IM to prevent GC development. In addition, the effects of the interventions were not uniform for each miRNA gene.

Current and future molecular diagnostics of gastric cancer

Introduction: Gastric cancer (GC) is the fifth most common cancer and confers the second-highest mortality among other cancers. Improving the survival rates of GC patients requires prompt and accurate diagnosis and effective treatment which is often preceded by the poorly understood pathogenic mechanisms. Area covered: This literature review aims to summarize current understanding of genetic and molecular alterations that promote carcinogenesis including (1) activation of oncogenes, (2) overexpression of growth factors, receptors and matrix metalloproteinases, (3) inactivation of tumor suppressor genes, DNA repair genes, and cell adhesion molecules and (4) alterations of cell-cycle regulators that regulate biological characteristics of cancer cells. Moreover, the significance of molecular biomarkers such as micro-RNAs (miRNAs) and long non-coding RNAs (lncRNAs) and advanced molecular techniques including droplet digital polymerase chain reaction (ddPCR), quantitative PCR (qPCR) and next-generation sequencing (NGS) are also discussed. Expert opinion: A GC-specific panel of biomarkers based on the NGS or ddPCR has the potential for diagnosis, prognosis, and monitoring treatment response in GC patients. Despite the requirements for validation in larger population in clinical studies, race-specific differences in the gene panel have also to be examined by performing the clinical trials in subjects with different races.

Droplet digital PCR as a novel system for the detection of microRNA‑34b/c methylation in circulating DNA in malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a rare malignancy arising from the pleura that is difficult to diagnose, contributing to its dismal prognosis. Previously, we reported that the degree of microRNA (miR)‑34b/c methylation in circulating DNA is associated with the development of MPM. Herein, we present a newly developed droplet digital PCR (ddPCR)‑based assay for the detection of miR‑34b/c methylation in circulating DNA in patients with MPM. We originally prepared two probes within a short amplicon of 60 bp, designing one from the positive strand and the other from the complementary strand. The two probes functioned cooperatively, and our established assay detected DNA methylation accurately in the preliminary validation. We subsequently verified this assay using clinical samples. Serum samples from 35 cases of MPM, 29 cases of pleural plaque and 10 healthy volunteers were collected from 3 different institutions and used in this study. We divided the samples into 2 groups (group A, n=33; group B, n=41). A receiver‑operating characteristic curve analysis using the samples in group A determined the optimal cut‑off value for the diagnosis of MPM, with a sensitivity of 76.9% and a specificity of 90%. On the other hand, the use of the same criterion yielded a sensitivity of 59.1% and a specificity of 100% in group B, and corresponding values of 65.7 and 94.9% for the entire cohort, indicating a moderate sensitivity and a high specificity. In addition, when the analysis was focused on stage II or more advanced MPM, the sensitivity improved to 81.8%, suggesting the possibility that the methylated allele frequency in MPM may be associated with the stage of disease progression. On the whole, the findings of this study indicate that miR‑34b/c methylation in circulating DNA is a promising biomarker for the prediction of disease progression in patients with MPM.

Detection and clinical significance of DNA repair gene ERCC8 tag SNPs in gastric cancer

BACKGROUND/AIMS

Excision repair cross-complementing group 8 (ERCC8) is one of the members of the nucleotide excision repair pathway. This study aimed to explore the association between ERCC8 tag single nucleotide polymorphisms (SNPs) and gastric cancer.

MATERIALS AND METHODS

Totally, 120 patients with gastric cancer treated from March 2010 to March 2011 were selected as the observation group and 120 healthy individuals were selected as the control group during the same period. The Sequenom MassARRAY system was used to identify genotypes in these samples. The genetic locus of ERCC8 tag SNPs and the relevance of gastric cancer risk to the different ERCC8 genotypes alone or in combination with Helicobacter pylori infection were observed and analyzed. The AA, GA, and GG genotypes on rs158572 and rs158916 in the observation and control groups were compared.

RESULTS

The results showed that the odds ratio of the different ERCC8 rs158572 and rs158916 genotypes was not significantly increased in the observation group compared with that in the control group. By contrast, in patients with H. pylori infection, the ERCC8 rs158572 GA/GG and rs158916 TT genotypes showed a 7.921-fold and 8.021-fold [95% confidence interval (CI)=4.022-15.921, p=0.029 and 95% CI=3.021-15.092, p=0.021, respectively] increased risk of gastric cancer than the AA and CT/CC genotypes, respectively.

CONCLUSION

Helicobacter pylori infection combined with ERCC8 rs158572 and rs158916 can be used as a predictive index of gastric cancer occurrence.

Helicobacter pylori Is Associated with miR-133a Expression through Promoter Methylation in Gastric Carcinogenesis

Background/Aims

To investigate whether Helicobacter pylori eradication can reverse epigenetic silencing of microRNAs (miRNAs) which are associated with H. pylori-induced gastric carcinogenesis.

Methods

We examined expression and promoter methylation of miR-34b/c, miR-133a, let-7a, and let-7i in gastric cancer cell line, before/after demethylation. Among them, epigenetically controlled miRNAs were identified. Their expression and promoter methylation was examined in human tissues of H. pylori-positive gastric cancer (T), H. pylori-positive gastritis (H), and H. pylori-negative controls (C). We also compared changes of miRNA expression and promoter methylation in H. pylori-positive patients who were endoscopically treated for early gastric cancer, between baseline and 1 year later according to eradication status.

Results

In gastric cancer cell line, miR-34b/c and miR-133a showed epigenetic silencing. In human tissues, miR-34b/c and miR-133a showed serial increase of promoter methylation in order of C, H, and T (all, p＜0.01), and the miR-133a expression showed serial decrease (C vs H, p=0.02; H vs T, p=0.01; C vs T, p＜0.01) while miR-34b and miR-34c expressions did not. H. pylori eradication induced decrease of methylation (p＜0.01) and increase of miR-133a expression (p=0.03), compared with noneradication group.

Conclusions

This result suggests H. pylori eradication could reverse methylation-silencing of miR-133a which is involved in H. pylori-induced gastric carcinogenesis.

Long-term effects of H. pylori eradication on epigenetic alterations related to gastric carcinogenesis

The risk of gastric cancer (GC) remains in precancerous conditions, including atrophic mucosa and intestinal mucosa (IM), even after H. pylori treatment. To define the molecular changes following H. pylori eradication, molecular alterations in the gastric mucosa with and without GC were evaluated in a long-term follow-up study. A total of 232 biopsy specimens from 78 consecutive patients, including atrophic gastritis patients with follow-up ≥3 y after successful H. pylori eradication (AG group), patients who developed early GC after successful eradication (≥3 y) (GC group), and patients with H. pylori-positive atrophic gastritis (Hp group), were analyzed. H. pylori eradication was associated with significant reductions of methylation of several genes/loci in atrophic mucosa (non-IM), but not in IM. In contrast, the incidence of CpG island methylator phenotype (CIMP) in IM was significantly higher in the GC group than in the AG group. miR-124a-3 methylation and miR-34c methylation were more frequently identified in IM, with very few in non-IM mucosa among the three groups. H. pylori eradication can reverse methylation only in non-IM mucosa. CIMP in IM may have potential as a surrogate maker of GC development, and methylation of miR-124a-3 and miR-34c is a molecular event in IM that may not be associated with GC development.

Diagnosis value of aberrantly expressed microRNA profiles in lung squamous cell carcinoma: a study based on the Cancer Genome Atlas

Background

Lung cancer is considered as one of the most frequent and deadly cancers with high mortality all around the world. It is critical to find new biomarkers for early diagnosis of lung cancer, especially lung squamous cell carcinoma (LUSC). The Cancer Genome Atlas (TCGA) is a database which provides both cancer and clinical information. This study is a comprehensive analysis of a novel diagnostic biomarker for LUSC, based on TCGA.

Methods and Results

The present study investigated LUSC-specific key microRNAs (miRNAs) from large-scale samples in TCGA. According to exclusion criteria and inclusion criteria, the expression profiles of miRNAs with related clinical information of 332 LUSC patients were obtained. Most aberrantly expressed miRNAs were identified between tumor and normal samples. Forty-two LUSC-specific intersection miRNAs (fold change >2, p < 0.05) were obtained by an integrative computational method, among them six miRNAs were found to be aberrantly expressed concerning characteristics of patients (gender, lymphatic metastasis, patient outcome assessment) through Student t-test. Five miRNAs correlated with overall survival (log-rank p < 0.05) were obtained through the univariate Cox proportional hazards regression model and Mantel–Haenszel test. Then, five miRNAs were randomly selected to validate the expression in 47 LUSC patient tissues using quantitative real-time polymerase chain reaction. The results showed that the test findings were consistent with the TCGA findings. Also, the diagnostic value of the specific key miRNAs was determined by areas under receiver operating characteristic curves. Finally, 577 interaction mRNAs as the targets of 42 LUSC-specific intersection miRNAs were selected for further bioinformatics analysis.

Conclusion

This study indicates that this novel microRNA expression signature may be a useful biomarker of the diagnosis for LUSC patients, based on bioinformatics analysis.

Helicobacter pylori infection and serum level of pepsinogen are associated with the risk of metachronous gastric neoplasm after endoscopic resection

BACKGROUND

Patients who have undergone endoscopic resection of early gastric cancers (EGCs) are at risk for metachronous gastric neoplasm.

AIM

To determine whether serum level of pepsinogen (PG), a marker of gastric atrophy, can determine which patients who have undergone endoscopic submucosal dissection for EGC are at risk for metachronous gastric neoplasm. We also investigated the effects of Helicobacter pylori eradication on metachronous gastric neoplasm incidence.

METHODS

We performed a retrospective study of 590 consecutive patients who underwent endoscopic submucosal dissection for EGC, from January 2008 to May 2013 at a tertiary centre in South Korea; serum levels of PG were measured at the time of endoscopic submucosal dissection and H. pylori infection status were recorded. In case of proven presence of current H. pylori infection, eradication treatment was provided. Patients underwent follow-up endoscopies at 3 months, 9 months, and each year after the procedure to detect neoplasms and were tested for H. pylori infection; serum levels of PG were measured at these time points from 442 of the patients. The main and sub-cohorts were assessed for baseline characteristics, H. pylori infection, serum level of PG, and metachronous gastric neoplasm lesions.

RESULTS

During a median follow-up period of 47.7 months, 64 patients developed metachronous gastric neoplasms. In multivariate analysis of the main cohort (n = 590), risk factors for metachronous gastric neoplasm included persistent H. pylori infection (hazard ratio [HR], 2.532; P = .022) and serum ratio of PGI:PGII of three or less at the time of endoscopic submucosal dissection (HR, 1.881; P = .018). Among patients with serum PG measurements, persistent H. pylori infection (odds ratio [OR], 4.404; P = .009) and persistent decrease in mean serum ratio of PGI:PGII to 3 or less were associated with increased risk of metachronous gastric neoplasm (OR, 2.141; P = .039).

CONCLUSIONS

In a retrospective analysis of patients who underwent endoscopic resection of EGCs, eradication of H. pylori infection reduced risk for metachronous gastric neoplasm. Serum ratio of PGI:PGII of 3 or less also increase risk of metachronous gastric neoplasm after endoscopic submucosal dissection. ClinicalTrials.gov. registry number, NCT02682446.

MicroRNA mediated regulation of immunity against gram-negative bacteria

Evidence over the last couple decades has comprehensively established that short, highly conserved, non-coding RNA species called microRNA (miRNA) exhibit the ability to regulate expression and function of host genes at the messenger RNA (mRNA) level. MicroRNAs play key regulatory roles in immune cell development, differentiation, and protective function. Intrinsic host immune response to invading pathogens rely on intricate orchestrated events in the development of innate and adaptive arms of immunity. We discuss the involvement of miRNAs in regulating these processes against gram negative pathogens in this review.

Morphologic characterization of residual DNA methylation in the gastric mucosa after Helicobacter pylori eradication

Residual DNA methylation in the gastric mucosa after Helicobacter pylori (H. pylori) eradication may have a role in gastric carcinogenesis. We examined the association between morphologic features and promoter methylation status of non‐neoplastic gastric mucosa especially after H. pylori eradication. A total of 140 gastric specimens from 99 participants who had at least 6 months of post‐eradication period were examined. The magnifying narrow‐band imaging (NBI) endoscopic feature of gastric mucosa was divided into two types: restored‐small, round pits, accompanied with honeycomb‐like subepithelial capillary networks; atrophic‐well‐demarcated oval or tubulovillous pits with clearly visible coiled or wavy vessels. Methylation status of five candidate genes (MYOD1, SLC16A12, IGF2, RORA, and PRDM5) were examined by bisulfite pyrosequencing. The atrophic type, informative endoscopic features of intestinal metaplasia, demonstrated higher methylation levels in all five genes compared to the restored type (all P < 0.0001). In the restored type, methylation levels were significantly lower among the samples with longer post‐eradication period (for all genes, P < 0.0001), which was not observed in atrophic type (for all genes, P > 0.1). Multivariate analysis demonstrated that atrophic type or presence of intestinal held an independent factor for hyper methylation (odds ratio: 24.69, 95% confidence interval: 6.95–87.76, P < 0.0001). The atrophic type by the magnifying NBI and presence of intestinal metaplasia are the morphologic characteristics of residual DNA methylation of after H. pylori eradication, regardless of the post‐eradication period and it might be considered as the epigenetic irreversible point with H. pylori eradication.

Overexpression of stromal interaction molecule 1 may promote epithelial‑mesenchymal transition and indicate poor prognosis in gastric cancer

The aim of the present study was to investigate the prognostic significance of stromal interaction molecule 1 (STIM1) expression in gastric cancer (GC) and examine the association between STIM1 and epithelial-mesenchymal transition (EMT). Immunohistochemical staining was performed to detect STIM1, E-cadherin, β-catenin and matrix metalloproteinase-9 (MMP-9) in 170 GC and 35 adjacent healthy gastric tissue samples. Positive staining of STIM1, E-cadherin, β-catenin and MMP-9 in GC tissues was significantly greater compared with adjacent healthy tissues (P<0.05). Clinicopathological analysis revealed that STIM1 expression was significantly associated with LNM (P<0.001) and tumor-node-metastasis stage (P=0.01). The overall survival rate was significantly reduced in STIM1-positive compared with STIM1-negative patients (P=0.043). Cox regression analysis indicated that STIM1 expression and LNM were independent prognostic factors for GC. Chi-square tests suggested that STIM1 expression in GC tissues was significantly associated with E-cadherin (P<0.001) and β-catenin (P<0.001), whereas no association was observed between STIM1 and MMP-9 expression (P>0.05). In conclusion, the results of the present study suggested that STIM1 may be a valuable prognostic marker in GC patients, and that STIM1 may increase GC motility and invasiveness by promoting epithelial-mesenchymal transition.

Oxysterol-Binding Protein-Related Protein 8 Inhibits Gastric Cancer Growth Through Induction of ER Stress, Inhibition of Wnt Signaling, and Activation of Apoptosis

Gastric cancer (GC) is the third leading cause of cancer-related mortality worldwide. Oxysterol-binding protein-related protein 8 (ORP8) functions as a sterol sensor that regulates a number of cellular functions. We showed that ORP8 expression was significantly lower in GC tissues and cells. Overexpression of ORP8 significantly inhibited GC cell proliferation in several GC cells. The formation of colonies in AGS cells was inhibited by the overexpression of ORP8. Moreover, overexpression of ORP8 significantly decreased implanted tumor growth in nude mice. Overexpression of ORP8 resulted in a significant increase in CHOP and GRP78 expression and the phosphorylation of PERK, indicating the occurrence of ER stress. Inhibition of ER stress by 4-PBA notably suppressed overexpression of ORP8-induced decrease of GC cell proliferation, formation of colonies, and implanted tumor growth. Overexpression of ORP8 resulted in a significant decrease in Wnt3a and β-catenin expression, and activation of Wnt signaling by HLY78 markedly blocked overexpression of ORP8-induced decrease in GC cell proliferation, formation of colonies, and implanted tumor growth. 4-PBA inhibited overexpression of ORP8-induced decrease in Wnt signaling. Furthermore, overexpression of ORP8 resulted in significant activation of mitochondrial apoptotic events and increase in apoptosis, which was inhibited by 4-PBA and HLY78. Induction of ER stress, inhibition of Wnt signaling, and apoptotic cell death were involved in ORP8-induced inhibition of GC cell proliferation. These findings indicate that downregulation of ORP8 plays a pivotal role in the progression of GC, and it may be a novel therapeutic target in the treatment of GC.

PFK15, a Small Molecule Inhibitor of PFKFB3, Induces Cell Cycle Arrest, Apoptosis and Inhibits Invasion in Gastric Cancer

PFKFB3 (6-phosphofructo-2-kinase) synthesizes fructose 2,6-bisphosphate (F2,6P₂), which is an allosteric activator of 6-phosphofructo-1-kinase (PFK-1), the rate-limiting enzyme of glycolysis. Overexpression of the PFKFB3 enzyme leads to high glycolytic metabolism, which is required for cancer cells to survive in the harsh tumor microenvironment. The objective of this study was to investigate the antitumor activity of PFK15 (1-(4-pyridinyl)-3-(2-quinolinyl)-2-propen-1-one), a small molecule inhibitor of PFKFB3, against gastric cancer and to explore its potential mechanisms. The effects of PFK15 on proliferation, apoptosis and cell cycle progression in gastric cancer cells were evaluated by cytotoxicity and apoptosis assays, flow cytometry, and western blotting. In addition, the invasion inhibition effects of PFK15 were measured by transwell invasion assay and western blot analysis, and a xenograft tumor model was used to verify the therapeutic effect of PFK15 in vivo. Results showed that PFK15 inhibited the proliferation, caused cell cycle arrest in G0/G1 phase by blocking the Cyclin-CDKs/Rb/E2F signaling pathway, and induced apoptosis through mitochondria in gastric cancer cells. Tumor volume and weight were also significantly reduced upon intraperitoneal injection with PFK15 at 25 mg/kg. In addition, PFK15 inhibited the invasion of gastric cancer cells by downregulating focal adhesion kinase (FAK) expression and upregulating E-cadherin expression. Taken together, our findings indicate that PFK15 is a promising anticancer drug for treating gastric cancer.

MiR-34b/c rs4938723 Polymorphism Significantly Decreases the Risk of Digestive Tract Cancer: Meta-analysis

BACKGROUND

Previous studies investigating the association between miR-34b/c rs4938723 polymorphism and cancer risk showed inconclusive. Here, we performed meta-analysis to investigate the association between miR- 34b/c rs4938723 polymorphism and digestive cancer risk.

MATERIALS AND METHODS

Literature database including PubMed, OVID, Chinese National Knowledge Infrastructure (CNKI) were searched for publications concerning the association between the miR-34b/c rs4938723 polymorphism and digestive cancer risk.

RESULTS

A total of 6 studies consisting of 3246 cases and 3568 controls were included in this meta-analysis. The combined analysis suggested the miR-34b/c rs4938723 polymorphism significantly reduced digestive cancer risk under allelic model, homogeneous co-dominant model and recessive model (C vs T: OR=0.88, 95%CI=0.82-0.95, p-value=0.001; CC vs TT: OR =0.67, 95%CI=0.57-0.80, p-value=0.000; CC vs

TT/TC

OR=0.68, 95%CI=0.58-0.80, p-value=0.000). Q-test and I2 test revealed no significant heterogeneity in all genotype comparisons. The Begger's funnel plot and Egger's test did not show significant publication bias.

CONCLUSIONS

The current evidence supports the conclusion that the miR-34b/c rs4938723 polymorphism decreases an individual's susceptibility to digestive cancers.

Endoscopic features associated with development of metachronous gastric cancer in patients who underwent endoscopic resection followed by Helicobacter pylori eradication

OBJECTIVES

The preventive effect of Helicobacter pylori (HP) eradication on metachronous gastric cancer development after endoscopic resection remains controversial. The aim of this study was to identify specific endoscopic features that correlated with the risk of metachronous gastric cancer development after endoscopic submucosal dissection (ESD) using both endoscopic findings before ESD and changes of findings after HP eradication.

METHODS

This retrospective study investigated 122 consecutive patients who underwent ESD for early gastric cancer and successful HP eradication after ESD. Endoscopic findings linked with HP before ESD and changes after HP eradication were evaluated according to the development of metachronous cancer.

RESULTS

Most patients showed severe atrophy and intestinal metaplasia (IM) before ESD (97% and 83%, respectively). Improvement of spotty redness, improvement of diffuse redness, emergence of patchy redness, and emergence of map-like redness were frequent findings after HP eradication (52%, 50%, 54%, and 32%, respectively). Kaplan-Meier curves indicated that patients without IM before ESD never developed metachronous cancer, while patients with emergence of map-like redness after HP eradication were significantly more likely to develop metachronous cancer (log-rank test, p = 0.031 and p < 0.001, respectively). Multivariate analysis indicated that emergence of map-like redness after HP eradication was the only predictive factor for development of metachronous cancer (hazard ratio, 3.61; 95% confidence interval, 1.41-9.21; p = 0.007).

CONCLUSIONS

Absence of IM before ESD and emergence of map-like redness after HP eradication were useful endoscopic findings in the negative and positive prediction of metachronous gastric cancer developing after ESD.

Gastric cancer: The times they are a-changin'

Gastric cancer is the third leading cause of cancer death worldwide. Even though during these last decades gastric cancer incidence decreased in Western countries, it remains endemic and with a high incidence in Eastern countries. The survival in advanced and metastatic stage of gastric cancer is still very poor. Recently the Cancer Genoma Atlas Research Network identified four subtypes with different molecular profiles to classify gastric cancer in order to offer the optimal targeted therapies for pre-selected patients. Indeed, the key point is still the selection of patients for the right treatment, on basis of molecular tumor characterization. Since chemotherapy reached a plateau of efficacy for gastric cancer, the combination between cytotoxic therapy and biological agents gets a better prognosis and decreases chemotherapeutic toxicity. Currently, Trastuzumab in combination with platinum and fluorouracil is the only approved targeted therapy in the first line for c-erbB2 positive patients, whereas Ramucirumab is the only approved targeted agent for patients with metastatic gastric cancer. New perspectives for an effective treatment derived from the immunotherapeutic strategies. Here, we report an overview on gastric cancer treatments, with particular attention to recent advances in targeted therapies and in immunotherapeutic approach.

Recent advances in the molecular diagnostics of gastric cancer

Gastric cancer (GC) is the third most common cause of cancer-related death in the world, representing a major global health issue. Although the incidence of GC is declining, the outcomes for GC patients remain dismal because of the lack of effective biomarkers to detect early GC and predict both recurrence and chemosensitivity. Current tumor markers for GC, including serum carcinoembryonic antigen and carbohydrate antigen 19-9, are not ideal due to their relatively low sensitivity and specificity. Recent improvements in molecular techniques are better able to identify aberrant expression of GC-related molecules, including oncogenes, tumor suppressor genes, microRNAs and long non-coding RNAs, and DNA methylation, as novel molecular markers, although the molecular pathogenesis of GC is complicated by tumor heterogeneity. Detection of genetic and epigenetic alterations from gastric tissue or blood samples has diagnostic value in the management of GC. There are high expectations for molecular markers that can be used as new screening tools for early detection of GC as well as for patient stratification towards personalized treatment of GC through prediction of prognosis and drug-sensitivity. In this review, the studies of potential molecular biomarkers for GC that have been reported in the publicly available literature between 2012 and 2015 are reviewed and summarized, and certain highlighted papers are examined.

Comparative analysis of methods to determine DNA methylation levels of a tumor-related microRNA gene

Quantifying levels of DNA methylation in tumors is a useful approach for the identification of potential tumor suppressors and to find biomarkers that can be used as prognostic or therapeutic indicators. In the current study, we compared three methods commonly used for quantifying DNA methylation-bisulfite pyrosequencing, quantitative methylation-specific PCR (Q-MSP), and MethyLight-by focusing on the CpG island of the gene encoding the microRNA-34b and microRNA-34c (miR-34b/c); aberrant regulation of this miR is associated with various human malignancies, including gastric cancer. Standard curve analysis using control DNA samples demonstrated the highest quantitative accuracy in Q-MSP analysis. We also carried out methylation analysis using gastric mucosa specimens obtained from gastric cancer patients. We found a high correlation between methylation levels determined by Q-MSP and those determined by MethyLight (R(2)=0.952), whereas the results of bisulfite pyrosequencing and the other two methods were less well correlated (R(2)=0.864 and R(2)=0.804 for Q-MSP and MethyLight, respectively). This may reflect possible PCR bias in the pyrosequencing technique, which we show can be corrected for by applying a cubic approximate equation to the original data. Thus, although results obtained by the different DNA methylation analysis techniques are largely comparable, an appropriate correction may be necessary for stringent comparison.

MicroRNAs: new players in IBD

MicroRNAs (miRNAs) are small non-coding RNAs, 18-23 nucleotides long, which act as post-transcriptional regulators of gene expression. miRNAs are strongly implicated in the pathogenesis of many common diseases, including IBDs. This review aims to outline the history, biogenesis and regulation of miRNAs. The role of miRNAs in the development and regulation of the innate and adaptive immune system is discussed, with a particular focus on mechanisms pertinent to IBD and the potential translational applications.

Gastric Carcinogenesis and Underlying Molecular Mechanisms: Helicobacter pylori and Novel Targeted Therapy

The oxygen-derived free radicals that are released from activated neutrophils are one of the cytotoxic factors of Helicobacter pylori-induced gastric mucosal injury. Increased cytidine deaminase activity in H. pylori-infected gastric tissues promotes the accumulation of various mutations and might promote gastric carcinogenesis. Cytotoxin-associated gene A (CagA) is delivered into gastric epithelial cells via bacterial type IV secretion system, and it causes inflammation and activation of oncogenic pathways. H. pylori infection induces epigenetic transformations, such as aberrant promoter methylation in tumor-suppressor genes. Aberrant expression of microRNAs is also reportedly linked to gastric tumorogenesis. Moreover, recent advances in molecular targeting therapies provided a new interesting weapon to treat advanced gastric cancer through anti-human epidermal growth factor receptor 2 (HER-2) therapies. This updated review article highlights possible mechanisms of gastric carcinogenesis including H. pylori-associated factors.

Promoter methylated microRNAs: potential therapeutic targets in gastric cancer

Gastric cancer (GC) is the fourth most commonly diagnosed type of cancer worldwide and has the second highest mortality rate of all cancer types. Classical genetics alone does not fully explain how GC occurs; however, epigenetics provides a partial explanation with regard to the cause of cancer. DNA methylation, the best-known type of epigenetic marker, represses the expression of tumor-suppressor genes and is involved in the pathogenesis of various types of human cancer, including GC. Micro (mi)RNAs are critical in the initiation, progression, metastasis and invasion of GC through gene regulation. The dysregulation of miRNAs is widely recognized as a hallmark of cancer. Recently, studies concerning DNA methylation of miRNAs in GC have been frequently reported, and these studies deepen the knowledge of how epigenetic regulation of miRNAs results in GC pathogenesis and indicate novel therapeutic strategies for GC. The present review provides an overview of the reported DNA methylation of miRNAs in GC.

Promoter polymorphisms of miR-34b/c are associated with risk of gastric cancer in a Chinese population

More and more evidence reveals that noncoding RNA miR-34b/c and tumor suppressor gene TP-53 independently, and/or jointly, play crucial roles in carcinogenesis. The purpose of the present hospital-based case-control study was to investigate the association between the miR-34b/c rs4938723 and TP53 Arg72Pro polymorphisms and the risk of gastric cancer. Two polymorphisms were genotyped in 419 gastric cancer patients and 402 age- and sex-matched cancer-free controls using polymerase chain reaction-restriction fragment length polymorphism analysis. The CC genotype and C allele of the miR-34b/c rs4938723 were associated with a significantly decreased risk of gastric cancer compared with the TT genotype and T allele (CC vs. TT: P = 0.006, adjusted odds ratio (OR) = 0.53, 95 % confidence interval (95 % CI) = 0.34-0.83; C vs. T: P = 0.005, adjusted OR = 0.75, 95 % CI = 0.61-0.92). Compared with individuals with the wild-type TT genotype, subjects with the variant genotypes (CT + CC) had a significantly decreased risk of gastric cancer (P = 0.047, adjusted OR = 0.75, 95 % CI = 0.57-0.99). Stratified analysis showed that the association between the risk of gastric cancer and the variant genotypes of miR-34b/c was more profound among men. However, no overall association was found between the TP53 Arg72Pro polymorphism and gastric cancer risk. In the combined analysis, no effects of the interaction of miR-34b/c rs4938723 and TP53Arg72Pro on gastric cancer risk were observed. Our findings indicate that the miR-34b/c rs4938723 CT/CC genotypes may be associated with a decreased risk of gastric cancer and the C allele may be a protective factor in gastric cancer.

Epigenetic alteration and microRNA dysregulation in cancer

MicroRNAs (miRNAs) play pivotal roles in numerous biological processes, and their dysregulation is a common feature of human cancer. Thanks to recent advances in the analysis of the cancer epigenome, we now know that epigenetic alterations, including aberrant DNA methylation and histone modifications, are major causes of miRNA dysregulation in cancer. Moreover, the list of miRNA genes silenced in association with CpG island hypermethylation is rapidly growing, and various oncogenic miRNAs are now known to be upregulated via DNA hypomethylation. Histone modifications also play important roles in the dysregulation of miRNAs, and histone deacetylation and gain of repressive histone marks are strongly associated with miRNA gene silencing. Conversely, miRNA dysregulation is causally related to epigenetic alterations in cancer. Thus aberrant methylation of miRNA genes is a potentially useful biomarker for detecting cancer and predicting its outcome. Given that many of the silenced miRNAs appear to act as tumor suppressors through the targeting of oncogenes, re-expression of the miRNAs could be an effective approach to cancer therapy, and unraveling the relationship between epigenetic alteration and miRNA dysregulation may lead to the discovery of new therapeutic targets.