Methylation of the CDH1 promoter as the second genetic hit in hereditary diffuse gastric cancer

Severe induction of aberrant DNA methylation by nodular gastritis in adults

BACKGROUND

Nodular gastritis (NG) is characterized by marked antral lymphoid follicle formation, and is a strong risk factor for diffuse-type gastric cancer in adults. However, it is unknown whether aberrant DNA methylation, which is induced by atrophic gastritis (AG) and is a risk for gastric cancer, is induced by NG. Here, we analyzed methylation induction by NG.

METHODS

Gastric mucosal samples were obtained from non-cancerous antral tissues of 16 NG and 20 AG patients with gastric cancer and 5 NG and 6 AG patients without, all age- and gender-matched. Genome-wide methylation analysis and expression analysis were conducted by a BeadChip array and RNA-sequencing, respectively.

RESULTS

Clustering analysis of non-cancerous antral tissues of NG and AG patients with gastric cancer was conducted using methylation levels of 585 promoter CpG islands (CGIs) of methylation-resistant genes, and a large fraction of NG samples formed a cluster with strong methylation induction. Promoter CGIs of CDH1 and DAPK1 tumor-suppressor genes were more methylated in NG than in AG. Notably, methylation levels of these genes were also higher in the antrum of NG patients without cancer. Genes related to lymphoid follicle formation, such as CXCL13/CXCR5 and CXCL12/CXCR4, had higher expression in NG, and genes involved in DNA demethylation TET2 and IDH1, had only half the expression in NG.

CONCLUSIONS

Severe aberrant methylation, involving multiple tumor-suppressor genes, was induced in the gastric antrum and body of patients with NG, in accordance with their high gastric cancer risk.

Pathogenesis and biomarkers of colorectal cancer by epigenetic alteration

Colorectal cancer (CRC) ranks third in cancer incidence and stands as the second leading cause of cancer-related deaths globally. CRC tumorigenesis results from a cumulative set of genetic and epigenetic alterations, disrupting cancer-regulatory processes like cell proliferation, metabolism, angiogenesis, cell death, invasion, and metastasis. Key epigenetic modifications observed in cancers encompass abnormal DNA methylation, atypical histone modifications, and irregularities in noncoding RNAs, such as microRNAs and long noncoding RNAs. The advancement in genomic technologies has positioned these genetic and epigenetic shifts as potential clinical biomarkers for CRC patients. This review concisely covers the fundamental principles of CRC-associated epigenetic changes, and examines in detail their emerging role as biomarkers for early detection, prognosis, and treatment response prediction.

Important role of DNA methylation hints at significant potential in tuberculosis

Tuberculosis (TB), an infectious disease caused by Mycobacterium tuberculosis (Mtb) infection, has persisted as a major global public health threat for millennia. Until now, TB continues to challenge efforts aimed at controlling it, with drug resistance and latent infections being the two main factors hindering treatment efficacy. The scientific community is still striving to understand the underlying mechanisms behind Mtb's drug resistance and latent infection. DNA methylation, a critical epigenetic modification occurring throughout an individual's growth and development, has gained attention following advances in high-throughput sequencing technologies. Researchers have observed abnormal DNA methylation patterns in the host genome during Mtb infection. Given the escalating issue of drug-resistant Mtb, delving into the role of DNA methylation in TB's development is crucial. This review article explores DNA methylation's significance in human growth, development and disease, and its role in regulating Mtb's evolution and infection processes. Additionally, it discusses potential applications of DNA methylation research in tuberculosis.

Driving effect of P16 methylation on telomerase reverse transcriptase-mediated immortalization and transformation of normal human fibroblasts

BACKGROUND

P16 inactivation is frequently accompanied by telomerase reverse transcriptase (TERT) amplification in human cancer genomes. P16 inactivation by DNA methylation often occurs automatically during immortalization of normal cells by TERT. However, direct evidence remains to be obtained to support the causal effect of epigenetic changes, such as P16 methylation, on cancer development. This study aimed to provide experimental evidence that P16 methylation directly drives cancer development.

METHODS

A zinc finger protein-based P16-specific DNA methyltransferase (P16-Dnmt) vector containing a "Tet-On" switch was used to induce extensive methylation of P16 CpG islands in normal human fibroblast CCD-18Co cells. Battery assays were used to evaluate cell immortalization and transformation throughout their lifespan. Cell subcloning and DNA barcoding were used to track the diversity of cell evolution.

RESULTS

Leaking P16-Dnmt expression (without doxycycline-induction) could specifically inactivate P16 expression by DNA methylation. P16 methylation only promoted proliferation and prolonged lifespan but did not induce immortalization of CCD-18Co cells. Notably, cell immortalization, loss of contact inhibition, and anchorage-independent growth were always prevalent in P16-Dnmt&TERT cells, indicating cell transformation. In contrast, almost all TERT cells died in the replicative crisis. Only a few TERT cells recovered from the crisis, in which spontaneous P16 inactivation by DNA methylation occurred. Furthermore, the subclone formation capacity of P16-Dnmt&TERT cells was two-fold that of TERT cells. DNA barcoding analysis showed that the diversity of the P16-Dnmt&TERT cell population was much greater than that of the TERT cell population.

CONCLUSION

P16 methylation drives TERT-mediated immortalization and transformation of normal human cells that may contribute to cancer development.

Mutational landscape of TP53 and CDH1 in gastric cancer

In this editorial we comment on an article published in a recent issue of the World J Gastrointest Surg. A common gene mutation in gastric cancer (GC) is the TP53 mutation. As a tumor suppressor gene, TP53 is implicated in more than half of all tumor occurrences. TP53 gene mutations in GC tissue may be related with clinical pathological aspects. The TP53 mutation arose late in the progression of GC and aided in the final switch to malignancy. CDH1 encodes E-cadherin, which is involved in cell-to-cell adhesion, epithelial structure maintenance, cell polarity, differentiation, and intracellular signaling pathway modulation. CDH1 mutations and functional loss can result in diffuse GC, and CDH1 mutations can serve as independent prognostic indicators for poor prognosis. GC patients can benefit from genetic counseling and testing for CDH1 mutations. Demethylation therapy may assist to postpone the onset and progression of GC. The investigation of TP53 and CDH1 gene mutations in GC allows for the investigation of the relationship between these two gene mutations, as well as providing some basis for evaluating the prognosis of GC patients.

Decoding the basis of histological variation in human cancer

Molecular abnormalities that shape human neoplasms dissociate their phenotypic landscape from that of the healthy counterpart. Through the lens of a microscope, tumour pathology optically captures such aberrations projected onto a tissue slide and has categorized human epithelial neoplasms into distinct histological subtypes based on the diverse morphogenetic and molecular programmes that they manifest. Tumour histology often reflects tumour aggressiveness, patient prognosis and therapeutic vulnerability, and thus has been used as a de facto diagnostic tool and for making clinical decisions. However, it remains elusive how the diverse histological subtypes arise and translate into pleiotropic biological phenotypes. Molecular analysis of clinical tumour tissues and their culture, including patient-derived organoids, and add-back genetic reconstruction of tumorigenic pathways using gene engineering in culture models and rodents further elucidated molecular mechanisms that underlie morphological variations. Such mechanisms include genetic mutations and epigenetic alterations in cellular identity codes that erode hard-wired morphological programmes and histologically digress tumours from the native tissues. Interestingly, tumours acquire the ability to grow independently of the niche-driven stem cell ecosystem along with these morphological alterations, providing a biological rationale for histological diversification during tumorigenesis. This Review comprehensively summarizes our current understanding of such plasticity in the histological and lineage commitment fostered cooperatively by molecular alterations and the tumour environment, and describes basic and clinical implications for future cancer therapy.

E-cadherin/β-catenin expression is conserved in human and rat erythropoiesis and marks stress erythropoiesis

E-cadherin is a crucial regulator of epithelial cell-to-cell adhesion and an established tumor suppressor. Aside epithelia, E-cadherin expression marks the erythroid cell lineage during human but not mouse hematopoiesis. However, the role of E-cadherin in human erythropoiesis remains unknown. Because rat erythropoiesis was postulated to reflect human erythropoiesis more closely than mouse erythropoiesis, we investigated E-cadherin expression in rat erythroid progenitors. E-cadherin expression is conserved within the erythroid lineage between rat and human. In response to anemia, erythroblasts in rat bone marrow (BM) upregulate E-cadherin as well as its binding partner β-catenin. CRISPR/Cas9-mediated knock out of E-cadherin revealed that E-cadherin expression is required to stabilize β-catenin in human and rat erythroblasts. Suppression of β-catenin degradation by glycogen synthase kinase 3β (GSK3β) inhibitor CHIR99021 also enhances β-catenin stability in human erythroblasts but hampers erythroblast differentiation and survival. In contrast, direct activation of β-catenin signaling, using an inducible, stable β-catenin variant, does not perturb maturation or survival of human erythroblasts but rather enhances their differentiation. Although human erythroblasts do not respond to Wnt ligands and direct GSK3β inhibition even reduces their survival, we postulate that β-catenin stability and signaling is mostly controlled by E-cadherin in human and rat erythroblasts. In response to anemia, E-cadherin-driven upregulation and subsequent activation of β-catenin signaling may stimulate erythroblast differentiation to support stress erythropoiesis in the BM. Overall, we uncover E-cadherin/β-catenin expression to mark stress erythropoiesis in rat BM. This may provide further understanding of the underlying molecular regulation of stress erythropoiesis in the BM, which is currently poorly understood.

Helicobacter pylori-associated Chronic Atrophic Gastritis and Progression of Gastric Carcinogenesis

Chronic inflammation due to a Helicobacter pylori (H. pylori) infection is a representative cause of gastric cancer that can promote gastric carcinogenesis by abnormally activating immune cells and increasing the inflammatory cytokines levels. H. pylori infections directly cause DNA double-strand breaks in gastric epithelial cells and genetic damage by increasing the enzymatic activity of cytidine deaminase. Eventually, gastric cancer is induced through dysplasia. Hypermethylation of tumor suppressor genes is an important cause of gastric cancer because of a H. pylori infection. In addition, the changes in gastric microbiota and the mucosal inflammatory changes associated with a co-infection with the Epstein-Barr virus are associated with gastric cancer development. DNA damage induced by H. pylori and the subsequent responses of gastric stem cells have implications for gastric carcinogenesis. Although the pathogenesis of H. pylori has been established, many uncertainties remain, requiring more study.

DoSurvive: A webtool for investigating the prognostic power of a single or combined cancer biomarker

We present DoSurvive, a user-friendly survival analysis web tool and a cancer prognostic biomarker centered database. DoSurvive is the first database that allows users to perform multivariant survival analysis for cancers with customized gene/patient list. DoSurvive offers three survival analysis methods, Log rank test, Cox regression and accelerated failure time model (AFT), for users to analyze five types of quantitative features (mRNA, miRNA, lncRNA, protein and methylation of CpG islands) with four survival types, i.e. overall survival, disease-specific survival, disease-free interval, and progression-free interval, in 33 cancer types. Notably, the implemented AFT model provides an alternative method for genes/features which failed the proportional hazard assumption in Cox regression. With the unprecedented number of survival models implemented and high flexibility in analysis, DoSurvive is a unique platform for the identification of clinically relevant targets for cancer researcher and practitioners. DoSurvive is freely available at http://dosurvive.lab.nycu.edu.tw/.

Neural crest E-cadherin loss drives cleft lip/palate by epigenetic modulation via pro-inflammatory gene-environment interaction

Gene-environment interactions are believed to play a role in multifactorial phenotypes, although poorly described mechanistically. Cleft lip/palate (CLP), the most common craniofacial malformation, has been associated with both genetic and environmental factors, with little gene-environment interaction experimentally demonstrated. Here, we study CLP families harbouring CDH1/E-Cadherin variants with incomplete penetrance and we explore the association of pro-inflammatory conditions to CLP. By studying neural crest (NC) from mouse, Xenopus and humans, we show that CLP can be explained by a 2-hit model, where NC migration is impaired by a combination of genetic (CDH1 loss-of-function) and environmental (pro-inflammatory activation) factors, leading to CLP. Finally, using in vivo targeted methylation assays, we demonstrate that CDH1 hypermethylation is the major target of the pro-inflammatory response, and a direct regulator of E-cadherin levels and NC migration. These results unveil a gene-environment interaction during craniofacial development and provide a 2-hit mechanism to explain cleft lip/palate aetiology.

Hereditary diffuse gastric cancer associated with a novel germline variant c.1596G>A in the <i>CDH1</i> gene

Gastric cancer is one of the most common malignancies worldwide. Approximately 10 % of patients with gastric cancer are characterized by accumulation of gastric cancer cases in their family. The hereditary forms of gastric cancer account for 1–3 % of all gastric cancer cases. Hereditary diffuse GC syndrome is caused by germline mutations in CDH1 gene and determines a high risk of developing diffuse GC and lobular breast cancer. In this article, we present a clinical case of a 41-year-old patient with diffuse gastric cancer, who was found to be a carrier of novel germline mutation in the CDH1 gene. Next-generation sequencing (NGS) has facilitated an identification of CDH1 c.1596G>A genetic variant, thus enabling an accurate clinical diagnosis hereditary diffuse gastric cancer.

Current advances in understanding the molecular profile of hereditary diffuse gastric cancer and its clinical implications

Hereditary diffuse gastric cancer (HDGC) is an autosomal dominant cancer syndrome attributed to germline CDH1 mutations that carries a high risk for early onset DGC. HDGC raises a significant health issue due to its high penetrance and mortality unless diagnosed early. The definitive treatment is to undergo prophylactic total gastrectomy which is associated with significant morbidity., highlighting the urgent need for alternative treatment methods. However, there is limited literature examining potential therapeutic strategies building on emerging insights into the molecular basis of progressive lesions in the context of HDGC. The aim of this review is to summarise the current understanding of HDGC in the context of CDH1 pathogenic variants followed by a review of the proposed mechanisms for progression. In addition, we discuss the development of novel therapeutic approaches and highlight pertinent areas for further research. A literature search was therefore performed for relevant studies examining CDH1 germline variants, second-hit mechanisms of CDH1, pathogenesis of HDGC and potential therapeutic strategies in databases, including PubMed, ScienceDirect and Scopus. Germline mutations are mostly truncating CDH1 variants affecting extracellular domains of E-cadherin, generally due to frameshift, single nucleotide variants or splice site mutations. A second somatic hit of CDH1 most commonly occurs via promoter methylation as shown in 3 studies, but studies are limited with a small sample size. The multi-focal development of indolent lesions in HDGC provide a unique opportunity to understand genetic events that drive the transition to the invasive phenotype. To date, a few signalling pathways have been shown to facilitate the progression of HDGC, including Notch and Wnt. In in-vitro studies, the ability to inhibit Notch signalling was lost in cells transfected with mutant forms of E-cadherin, and increased Notch-1 activity correlated with apoptosis resistance. Furthermore, in patient samples, overexpression of Wnt-2 was associated with cytoplasmic and nuclear β-catenin accumulation and increased metastatic potential. As loss-of-function mutations are challenging to target therapeutically, these findings pave the way towards a synthetic lethal approach in CDH1-deficient cells with some promising results in-vitro. In future, if we could better understand the molecular vulnerabilities in HDGC, there may be opportunities to offer alternative treatment pathways to avoid gastrectomy.

Hereditary Diffuse Gastric Cancer: A 2022 Update

Gastric cancer is ranked fifth among the most commonly diagnosed cancers, and is the fourth leading cause of cancer-related deaths worldwide. The majority of gastric cancers are sporadic, while only a small percentage, less than 1%, are hereditary. Hereditary diffuse gastric cancer (HDGC) is a rare malignancy, characterized by early-onset, highly-penetrant autosomal dominant inheritance mainly of the germline alterations in the E-cadherin gene (CDH1) and β-catenin (CTNNA1). In the present study, we provide an overview on the molecular basis of HDGC and outline the essential elements of genetic counseling and surveillance. We further provide a practical summary of current guidelines on clinical management and treatment of individuals at risk and patients with early disease.

Landscape of Druggable Molecular Pathways Downstream of Genomic CDH1/Cadherin-1 Alterations in Gastric Cancer

Loss of CDH1/Cadherin-1 is a common step towards the acquisition of an abnormal epithelial phenotype. In gastric cancer (GC), mutation and/or downregulation of CDH1/Cadherin-1 is recurrent in sporadic and hereditary diffuse GC type. To approach the molecular events downstream of CDH1/Cadherin-1 alterations and their relevance in gastric carcinogenesis, we queried public databases for genetic and DNA methylation data in search of molecular signatures with a still-uncertain role in the pathological mechanism of GC. In all GC subtypes, modulated genes correlating with CDH1/Cadherin-1 aberrations are associated with stem cell and epithelial-to-mesenchymal transition pathways. A higher level of genes upregulated in CDH1-mutated GC cases is associated with reduced overall survival. In the diffuse GC (DGC) subtype, genes downregulated in CDH1-mutated compared to cases with wild type CDH1/Cadherin-1 resulted in being strongly intertwined with the DREAM complex. The inverse correlation between hypermethylated CpGs and CDH1/Cadherin-1 transcription in diverse subtypes implies a common epigenetic program. We identified nonredundant protein-encoding isoforms of 22 genes among those differentially expressed in GC compared to normal stomach. These unique proteins represent potential agents involved in cell transformation and candidate therapeutic targets. Meanwhile, drug-induced and CDH1/Cadherin-1 mutation-related gene expression comparison predicts FIT, GR-127935 hydrochloride, amiodarone hydrochloride in GC and BRD-K55722623, BRD-K13169950, and AY 9944 in DGC as the most effective treatments, providing cues for the design of combined pharmacological treatments. By integrating genetic and epigenetic aspects with their expected functional outcome, we unveiled promising targets for combinatorial pharmacological treatments of GC.

E-Cadherin Expression Distinguishes Mouse from Human Hematopoiesis in the Basophil and Erythroid Lineages

E-cadherin is a key regulator of epithelial cell–cell adhesion, the loss of which accelerates tumor growth and invasion. E-cadherin is also expressed in hematopoietic cells as well as epithelia. The function of hematopoietic E-cadherin is, however, mostly elusive. In this study, we explored the validity of mouse models to functionally investigate the role of hematopoietic E-cadherin in human hematopoiesis. We generated a hematopoietic-specific E-cadherin knockout mouse model. In mice, hematopoietic E-cadherin is predominantly expressed within the basophil lineage, the expression of which is dispensable for the generation of basophils. However, neither E-cadherin mRNA nor protein were detected in human basophils. In contrast, human hematopoietic E-cadherin marks the erythroid lineage. E-cadherin expression in hematopoiesis thereby revealed striking evolutionary differences between the basophil and erythroid cell lineage in humans and mice. This is remarkable as E-cadherin expression in epithelia is highly conserved among vertebrates including humans and mice. Our study therefore revealed that the mouse does not represent a suitable model to study the function of E-cadherin in human hematopoiesis and an alternative means to study the role of E-cadherin in human erythropoiesis needs to be developed.

Hereditary Diffuse Gastric Cancer: Molecular Genetics, Biological Mechanisms and Current Therapeutic Approaches

Hereditary diffuse gastric cancer is an autosomal dominant syndrome characterized by a high prevalence of diffuse gastric cancer and lobular breast cancer. It is caused by inactivating mutations in the tumor suppressor gene CDH1. Genetic testing technologies have become more efficient over the years, also enabling the discovery of other susceptibility genes for gastric cancer, such as CTNNA1 among the most important genes. The diagnosis of pathogenic variant carriers with an increased risk of developing gastric cancer is a selection process involving a multidisciplinary team. To achieve optimal long-term results, it requires shared decision-making in risk management. In this review, we present a synopsis of the molecular changes and current therapeutic approaches in HDGC based on the current literature.

Familial and hereditary gastric cancer, an overview

There are three major hereditable syndromes that affect primarily the stomach: hereditary diffuse gastric cancer (HDGC), gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS) and familial intestinal gastric cancer (FIGC). HDGC is caused by germline mutations in CDH1 gene that occur in 10-40% of HDGC families and, in a minority of cases, by mutations in CTNNA1 gene. GAPPS is caused by germline mutations in the promoter 1B of APC gene, and the genetic cause of FIGC is not fully elucidated. Gastric cancer can also be observed as part of other inherited cancer disorders, namely in familial adenomatous polyposis, MUTYH-associated polyposis, Peutz-Jeghers syndrome, juvenile polyposis syndrome, Lynch syndrome, Li-Fraumeni syndrome, Cowden syndrome, and hereditary breast and ovarian cancer syndrome. In this article, the state of the art of familial gastric cancer regarding the clinical, molecular and pathology features is reviewed, as well as the practical aspects for a correct diagnosis and clinical management.

Diffuse gastric cancer: Emerging mechanisms of tumor initiation and progression

Gastric cancer is globally the fourth leading cause of cancer-related deaths. Patients with diffuse-type gastric cancer (DGC) particularly have a poor prognosis that only marginally improved over the last decades, as conventional chemotherapies are frequently ineffective and specific therapies are unavailable. Early-stage DGC is characterized by intramucosal lesions of discohesive cells, which can be present for many years before the emergence of advanced DGC consisting of highly proliferative and invasive cells. The mechanisms underlying the key steps of DGC development and transition to aggressive tumors are starting to emerge. Novel mouse- and organoid models for DGC, together with multi-omic analyses of DGC tumors, revealed contributions of both tumor cell-intrinsic alterations and gradual changes in the tumor microenvironment to DGC progression. In this review, we will discuss how these recent findings are leading towards an understanding of the cellular and molecular mechanisms responsible for DGC initiation and malignancy, which may provide opportunities for targeted therapies.

E-Cadherin-Deficient Epithelial Cells Are Sensitive to HDAC Inhibitors

Inactivating germline mutations in the CDH1 gene (encoding the E-cadherin protein) are the genetic hallmark of hereditary diffuse gastric cancer (HDGC), and somatic CDH1 mutations are an early event in the development of sporadic diffuse gastric cancer (DGC) and lobular breast cancer (LBC). In this study, histone deacetylase (HDAC) inhibitors were tested for their ability to preferentially inhibit the growth of human cell lines (MCF10A and NCI-N87) and murine organoids lacking CDH1 expression. CDH1^-/- breast and gastric cells were more sensitive to the pan-HDAC inhibitors entinostat, pracinostat, mocetinostat and vorinostat than wild-type cells, with an elevated growth inhibition that was, in part, attributable to increased apoptosis. CDH1-null cells were also sensitive to more class-specific HDAC inhibitors, but compared to the pan-inhibitors, these effects were less robust to genetic background. Increased sensitivity to entinostat was also observed in gastric organoids with both Cdh1 and Tp53 deletions. However, the deletion of Tp53 largely abrogated the sensitivity of the Cdh1-null organoids to pracinostat and mocetinostat. Finally, entinostat enhanced Cdh1 expression in heterozygous Cdh1^+/- murine organoids. In conclusion, entinostat is a promising drug for the chemoprevention and/or treatment of HDGC and may also be beneficial for the treatment of sporadic CDH1-deficient cancers.

Effect of Helicobacter pylori Eradication on Epigenetic Changes in Gastric Cancer-related Genes

It is known that gastric carcinogenesis results from the progressive changes from chronic gastritis to gastric atrophy, intestinal metaplasia, dysplasia, and invasive carcinoma. Several genetic and epigenetic alterations are involved in this process, and Helicobacter pylori (H. pylori) infection is believed to induce the initiation and progression of these steps. From an epigenetic point of view, H. pylori induces hypermethylation of genes involved in the development of gastric cancer and regulates the expression of various microRNAs (miRNAs). These H. pylori-related epigenetic changes are accumulated not only at the site of neoplasm but also in the adjacent non-cancerous gastric mucosa. Thereby, a state vulnerable to gastric cancer known as an epigenetic field defect is formed. H. pylori eradication can have an effective chemopreventive effect in gastric carcinogenesis. However, the molecular biological changes that occur in the stomach environment during H. pylori eradication have not yet been established. Several studies have reported that H. pylori eradication can restore infection-related changes, especially epigenetic alterations in gastric cancer-related genes, but some studies have shown otherwise. Simply put, it appears that the recovery of methylated gastric cancer-related genes and miRNAs during H. pylori eradication may vary among genes and may also differ depending on the histological subtype of the gastric mucosa. In this review, we will discuss the potential mechanism of gastric cancer prevention by H. pylori eradication, mainly from an epigenetic perspective.

Gastric cancer genetic predisposition and clinical presentations: Established heritable causes and potential candidate genes

Tumour risk syndromes (TRS) are characterized by an increased risk of early-onset cancers in a familial context. High cancer risk is mostly driven by loss-of-function variants in a single cancer-associated gene. Presently, predisposition to diffuse gastric cancer (DGC) is explained by CDH1 and CTNNA1 pathogenic and likely pathogenic variants (P/LP), causing Hereditary Diffuse Gastric Cancer (HDGC); while APC promoter 1B single nucleotide variants predispose to Gastric Adenocarcinoma and Proximal Polyposis of the Stomach (GAPPS). Familial Intestinal Gastric Cancer (FIGC), recognized as a GC-predisposing disease, remains understudied and genetically unsolved. GC can also occur in the spectrum of other TRS. Identification of heritable causes allows defining diagnostic testing criteria, helps to clinically classify GC families into the appropriate TRS, and allows performing pre-symptomatic testing identifying at-risk individuals for downstream surveillance, risk reduction and/or treatment. However, most of HDGC, some GAPPS, and most FIGC patients/families remain unsolved, expecting a heritable factor to be discovered. The missing heritability in GC-associated tumour risk syndromes (GC-TRS) is likely explained not by a single major gene, but by a diversity of genes, some, predisposing to other TRS. This would gain support if GC-enriched small families or apparently isolated early-onset GC cases were hiding a family history compatible with another TRS. Herein, we revisited current knowledge on GC-TRS, and searched in the literature for individuals/families bearing P/LP variants predisposing for other TRS, but whose probands display a clinical presentation and/or family history also fitting GC-TRS criteria. We found 27 families with family history compatible with HDGC or FIGC, harbouring 28 P/LP variants in 16 TRS-associated genes, mainly associated with DNA repair. PALB2 or BRCA2 were the most frequently mutated candidate genes in individuals with family history compatible with HDGC and FIGC, respectively. Consolidation of PALB2 and BRCA2 as HDGC- or FIGC-associated genes, respectively, holds promise and worth additional research. This analysis further highlighted the influence, that proband's choice and small or unreported family history have, for a correct TRS diagnosis, genetic screening, and disease management. In this review, we provide a rational for identification of particularly relevant candidate genes in GC-TRS.

Dual role of E-cadherin in cancer cells

E-cadherin is the main component of epithelial adherens junctions (AJs), which play a crucial role in the maintenance of stable cell-cell adhesion and overall tissue integrity. Down-regulation of E-cadherin expression has been found in many carcinomas, and loss of E-cadherin is generally associated with poor prognosis in patients. During the last decade, however, numerous studies have shown that E-cadherin is essential for several aspects of cancer cell biology that contribute to cancer progression, most importantly, active cell migration. In this review, we summarize the available data about the input of E-cadherin in cancer progression, focusing on the latest advances in the research of the various roles E-cadherin-based AJs play in cancer cell dissemination. The review also touches upon the "cadherin switching" in cancer cells where N- or P-cadherin replace or are co-expressed with E-cadherin and its influence on the migratory properties of cancer cells.

Molecular Landscapes of Gastric Pre-Neoplastic and Pre-Invasive Lesions

Gastric carcinoma (GC) represents one of the most common and most lethal malignancies worldwide. The histopathological characterization of GC precursor lesions has provided great knowledge about gastric carcinogenesis, with the consequent introduction of effective strategies of primary and secondary prevention. In recent years, a large amount of data about the molecular events in GC development is emerging, flanking the histomorphological descriptions. In this review, we describe the landscape of molecular alterations in gastric pre-invasive lesions with a glance at their potential use in the diagnostic and therapeutic decision-making process.

Overview on the Role of E-Cadherin in Gastric Cancer: Dysregulation and Clinical Implications

Gastric cancer is the fifth most common cancer and the third most common cause of cancer death all over the world. E-cadherin encoded by human CDH1 gene plays important roles in tumorigenesis as well as in tumor progression, invasion and metastasis. Full-length E-cadhrin tethered on the cell membrane mainly mediates adherens junctions between cells and is involved in maintaining the normal structure of epithelial tissues. After proteolysis, the extracellular fragment of the full-length E-cadhein is released into the extracellular environment and the blood, which is called soluble E-cadherin (sE-cadherin). sE-cadherin promots invasion and metastasis as a paracrine/autocrine signaling molecule in the progression of various types of cancer including gastric cancer. This review mainly summarizes the dysregulation of E-cadherin and the regulatory roles in the progression, invasion, metastasis, and drug-resistance, as well as its clinical applications in diagnosis, prognosis, and therapeutics of gastric cancer.

Navigating the DNA methylation landscape of cancer

DNA methylation is a chemical modification that defines cell type and lineage through the control of gene expression and genome stability. Disruption of DNA methylation control mechanisms causes a variety of diseases, including cancer. Cancer cells are characterized by aberrant DNA methylation (i.e., genome-wide hypomethylation and site-specific hypermethylation), mainly targeting CpG islands in gene expression regulatory elements. In particular, the early findings that a variety of tumor suppressor genes (TSGs) are targets of DNA hypermethylation in cancer led to the proposal of a model in which aberrant DNA methylation promotes cellular oncogenesis through TSGs silencing. However, recent genome-wide analyses have revealed that this classical model needs to be reconsidered. In this review, we will discuss the molecular mechanisms of DNA methylation abnormalities in cancer as well as their therapeutic potential.

Genetic and Epigenetic Alterations of CDH1 Regulatory Regions in Hereditary and Sporadic Gastric Cancer

E-cadherin is a key player in gastric cancer (GC) and germline alterations of CDH1, its encoding gene, are responsible for Hereditary Diffuse Gastric Cancer (HDGC) syndrome. This study aimed at elucidating the role of genetic variants and DNA methylation of CDH1 promoter and enhancers in the regulation of gene expression. For this purpose, we analyzed genetic variants of the CDH1 gene through Next-Generation Sequencing (NGS) in a series of GC cell lines (NCI-N87, KATO-III, SNU-1, SNU-5, GK2, AKG, KKP) and the corresponding CDH1 expression levels. By bisulfite genomic sequencing, we analyzed the methylation status of CDH1 regulatory regions in 8 GC cell lines, in a series of 13 sporadic GC tissues and in a group of 20 HDGC CDH1-negative patients and 6 healthy controls. The NGS analysis on CDH1 coding and regulatory regions detected genetic alterations in 3 out of 5 GC cell lines lacking functional E-cadherin. CDH1 regulatory regions showed different methylation patterns in patients and controls, GC cell lines and GC tissues, expressing different E-cadherin levels. Our results showed that alterations in terms of genetic variants and DNA methylation patterns of both promoter and enhancers are associated with CDH1 expression levels and have a role in its regulation.

Hereditary Diffuse Gastric Cancer Syndrome and the Role of CDH1: A Review

Importance

Inherited variants in the tumor suppressor gene CDH1 are associated with an increased risk of gastric and breast cancers. This review aims to address the most current topics in management of the hereditary diffuse gastric cancer syndrome attributed to CDH1.

Observations

Consensus management guidelines have broadened genetic testing criteria for CDH1. Prophylactic total gastrectomy is recommended for any pathogenic or likely pathogenic CDH1 variant carrier starting at the age of 20 years. Annual surveillance endoscopy is recommended to those who defer prophylactic total gastrectomy. Women with a CDH1 variant should initiate magnetic resonance imaging breast surveillance starting at age 30 years. Further research is needed to understand the pathogenesis of early-stage gastric cancers (T1a), which are pathognomonic of hereditary diffuse gastric cancer syndrome, that lead to advanced gastric cancer to develop both treatment and prevention strategies for this patient population.

Conclusions and Relevance

The heritable CDH1 gene mutation is of importance to today's surgeons because it is associated with a substantial increased risk of developing both gastric and breast cancers. Management of this cancer syndrome currently uses prophylactic surgery and enhanced cancer surveillance strategies.

Epigenetic alterations in the gastrointestinal tract: Current and emerging use for biomarkers of cancer

Colorectal cancer is a leading cause of cancer related deaths worldwide. One of the hallmarks of cancer and a fundamental trait of virtually all gastrointestinal cancers is genomic and epigenomic DNA alterations. Cancer cells acquire genetic and epigenetic alterations that drive the initiation and progression of the cancers by altering the molecular and cell biological process of the cells. These alterations, as well as other host and microenvironment factors, ultimately mediate the initiation and progression of cancers, including colorectal cancer. Epigenetic alterations, which include changes affecting DNA methylation, histone modifications, chromatin structure, and noncoding RNA expression, have emerged as a major class of molecular alteration in colon polyps and colorectal cancer. The classes of epigenetic alterations, their status in colorectal polyps and cancer, their effects on neoplasm biology, and their application to clinical care will be discussed.

Epigenetic Alterations in the Gastrointestinal Tract: Current and Emerging Use for Biomarkers of Cancer

Colorectal cancer, liver cancer, stomach cancer, pancreatic cancer, and esophageal cancer are leading causes of cancer-related deaths worldwide. A fundamental trait of virtually all gastrointestinal cancers is genomic and epigenomic DNA alterations. Cancer cells acquire genetic and epigenetic alterations that drive the initiation and progression of the cancers by altering the molecular and cell biological processes of the cells. These alterations, as well as other host and microenvironment factors, ultimately mediate the clinical behavior of the precancers and cancers and can be used as biomarkers for cancer risk determination, early detection of cancer and precancer, determination of the prognosis of cancer and prediction of the response to therapy. Epigenetic alterations have emerged as one of most robust classes of biomarkers and are the basis for a growing number of clinical tests for cancer screening and surveillance.

DNA methylome profiling of circulating tumor cells in lung cancer at single base-pair resolution

DNA methylation plays a pivotal role in regulating cellular processes, and altered DNA methylation pattern is a general hallmark of cancer. However, DNA methylome in circulating tumor cells (CTCs) is still a mystery due to the lack of proper analytical techniques. We introduced an efficient workflow, LCM-µWGBS, which can efficiently profile the DNA methylation of microdissected CTC samples. LCM-µWGBS combines the laser capture microdissection (LCM)-based CTC capture method and whole-genome bisulfite sequencing in very small CTC population (µWGBS) to gain insight into the DNA methylation landscape of CTCs. We herein profiled the DNA methylome of CTCs from lung cancer patients. Deriving from a comprehensive analysis of CTC methylome, a unique "CTC DNA methylation signature" that is distinct from primary lung cancer tissues was identified. Further analysis showed that promoter hypermethylation of epithelial genes is a hallmark of stable epithelial-mesenchymal transition process. Moreover, it has been suggested that CTCs are endowed with a stemness-related feature during dissemination and metastasis. This work constitutes a unique DNA methylation analysis of CTCs at single base-pair resolution, which might facilitate to propose noninvasive CTC DNA methylation biomarkers contributing to clinical diagnosis.

Biomarkers for Early Detection of Colorectal Cancer: The Early Detection Research Network, a Framework for Clinical Translation

Early detection by screening significantly reduces mortality from colorectal cancer, but 40% of guideline-eligible patients are not screened as recommended in the United States. Novel strategies to improve screening uptake overall and efforts to deploy best practices to underserved populations are a high priority for health care. This review focuses on existing biomarkers in practice and those in development with clinical relevance to early detection of colorectal neoplasia, with an emphasis on those developed by investigators of the NCI's Early Detection Research Network. Aberrantly methylated DNA markers (blood and stool), stool-based markers (including fecal immunochemical test-DNA), and a variety of blood-based marker assays in development (protein markers, glycoproteins including mucins, and cell-free DNA tests) are reviewed. Individual markers and biomarker panels, sample resources, and barriers to translating biomarkers to clinical practice are discussed.See all articles in this CEBP Focus section, "NCI Early Detection Research Network: Making Cancer Detection Possible."

Diffuse gastric cancer: histologic, molecular, and genetic basis of disease

Diffuse gastric cancer (DGC) is a distinct histopathologic and molecular disease, characterized by mutations in CDH1, RHOA, and others. In addition, DGC is associated with familial syndromes, including hereditary DGC and germline mutation in CDH1. Clinically, this subtype of gastric adenocarcinoma is associated with a poor prognosis and possible resistance to available systemic therapies. An understanding of the genetic and molecular underpinnings of DGC may help inform of its clinical behavior and aid in screening, diagnosis, and response to treatment. In this review, we will review the current histologic, molecular, and genetic landscape of DGC and its relevance to clinical practice.

Significance of E-cadherin Gene Mutations in Patients With Hereditary Diffuse Gastric Cancer Syndrome: A Systematic Review

Gastric cancer is the third-most fatal cancer in the world. Though over the years, we saw patients mostly with intestinal type accounting for the highest mortality rate, the recent rise of the diffuse form with germline E-cadherin (CDH1) mutations has added a whole new level of interest to study in detail about the association between CDH1 and diffuse gastric cancer (DGC). This introduced a set guideline formulated by Internal Gastric Cancer Linkage Consortium (IGCLC) for patients with family history of diffuse gastric cancer and invasive lobular breast cancer (ILBC). The analysis of this link was also important to set proper management protocol for patients who were CDH1 mutation carriers which now involves genetic counselling, endoscopic surveillance and screening and prophylactic total gastrectomy (PTG). The study was conducted in accordance to the ‘PRISMA guidelines for reporting systematic review and meta-analysis’. Peer-reviewed studies were included from the PubMed database and relevant articles were selected to be included in the study. Appropriate inclusion/exclusion criteria with free full text English articles were applied while selecting the articles. A total of 10 studies on review with different study populations showed that of the 42 patients who were diagnosed with diffuse gastric cancer, 88% of them showed a positive germline E-cadherin gene mutation and 100% of the CDH1 mutation carriers showed microscopic changes of signet ring cell adenocarcinoma of the stomach. The beneficial effects of PTG with better survival rates and low mortality rates has outweighed other treatment modalities. Laparoscopic approach has proved to be more useful and a safer approach for gastrectomy surgeries with better post-operative management. The need for prophylactic mastectomy is also increased in the recent times and thus this requires a new set of guidelines for ILBC patients with hereditary diffuse gastric cancer (HDGC) syndrome.

Overview on new progress of hereditary diffuse gastric cancer with CDH1 variants

Hereditary diffuse gastric cancer (HDGC), comprising 1%-3% of gastric malignances, has been associated with CDH1 variants. Accumulating evidence has demonstrated more than 100 germline CDH1 variant types. E-cadherin encoded by the CDH1 gene serves as a tumor suppressor protein. CDH1 promoter hypermethylation and other molecular mechanisms resulting in E-cadherin dysfunction are involved in the tumorigenesis of HDGC. Histopathology exhibits characteristic signet ring cells, and immunohistochemical staining may show negativity for E-cadherin and other signaling proteins. Early HDGC is difficult to detect by endoscopy due to the development of lesions beneath the mucosa. Prophylactic gastrectomy is the most recommended treatment for pathogenic CDH1 variant carriers. Recent studies have promoted the progression of promising molecular-targeted therapies and management strategies. This review summarizes recent advances in CDH1 variant types, tumorigenesis mechanisms, diagnosis, and therapy, as well as clinical implications for future gene therapies.

Multifaceted Roles of DNA Methylation in Neoplastic Transformation, from Tumor Suppressors to EMT and Metastasis

Among the major mechanisms involved in tumorigenesis, DNA methylation is an important epigenetic modification impacting both genomic stability and gene expression. Methylation of promoter-proximal CpG islands (CGIs) and transcriptional silencing of tumor suppressors represent the best characterized epigenetic changes in neoplastic cells. The global cancer-associated effects of DNA hypomethylation influence chromatin architecture and reactivation of repetitive elements. Moreover, recent analyses of cancer cell methylomes highlight the role of the DNA hypomethylation of super-enhancer regions critically controlling the expression of key oncogenic players. We will first summarize some basic aspects of DNA methylation in tumorigenesis, along with the role of dysregulated DNA methyltransferases and TET (Ten-Eleven Translocation)-family methylcytosine dioxygenases. We will then examine the potential contribution of epimutations to causality and heritability of cancer. By reviewing some representative genes subjected to hypermethylation-mediated silencing, we will survey their oncosuppressor functions and roles as biomarkers in various types of cancer. Epithelial-to-mesenchymal transition (EMT) and the gain of stem-like properties are critically involved in cancer cell dissemination, metastasis, and therapeutic resistance. However, the driver vs passenger roles of epigenetic changes, such as DNA methylation in EMT, are still poorly understood. Therefore, we will focus our attention on several aspects of DNA methylation in control of EMT and metastasis suppressors, including both protein-coding and noncoding genes.

Integrated multi-omics data analyses for exploring the co-occurring and mutually exclusive gene alteration events in colorectal cancer

Co-occurring and mutually exclusive gene alteration events are helpful for understanding carcinogenesis but systematic screening for such events is quite limited. We conducted pairwise screening tests to identify "hit pairs" in colorectal cancer (CRC) by utilizing the cross-omics data from The Cancer Genome Atlas (TCGA). Numerous hit pairs involving somatic mutations, copy number variations, and DNA methylation were found to occur nonrandomly in CRC, such as KRAS and HOXB6, SMAD4 and PMEPA1. Based on these hit pairs, we identified 32 synthetic lethal pairs and 7,527 co-occurring pairs relating to drug response. Our further biological experiments showed that the co-occurrence of mutant FCGBP and NUDT12 silencing (or mutant TMC3 and RPS6KA6 silencing) with small interfering RNA reduced cell viability. Moreover, novel hit pairs could influence prognosis. The patients who carried concurrent mutations of IRF5 and NEFH, SYNE1 and TTN, or MUC16 and NEFH had worse survival outcomes. Particularly, the presence of mutant SYNE1 and TTN pair not only affects prognosis, but also is related to CRC patients' response to drug treatment. Our "hit pair" genes may provide insights into colorectal carcinogenesis and help open new avenues for CRC therapy.

Case report: acute abdominal pain in a 37-year-old patient and the consequences for his family

Background

Hereditary diffuse gastric cancer is a rare condition that accounts for approximately 1–3% of all gastric cancer cases. Due to its rapid and invasive growth pattern, it is associated with a very poor prognosis. As a result, comprehensive genetic testing is imperative in patients who meet the current testing criteria in order to identify relatives at risk. This case report illustrates the substantial benefit of genetic testing in the family of a patient diagnosed with hereditary diffuse gastric cancer.

Case presentation

A 37-year-old patient was admitted to the emergency department with acute abdominal pain. Following explorative laparoscopy, locally advanced diffuse gastric cancer was diagnosed. The indication for genetic testing of CDH1 was given due to the patient’s young age. A germline mutation in CDH1 was identified in the index patient. As a result, several family members underwent genetic testing. The patient’s father, brother and one aunt were identified as carriers of the familial CDH1 mutation and subsequently received gastrectomy. In both the father and the aunt, histology of the surgical specimen revealed a diffuse growing adenocarcinoma after an unremarkable preoperative gastroscopy.

Conclusion

Awareness and recognition of a potential hereditary diffuse gastric cancer can provide a substantial health benefit not only for the patient but especially for affected family members.

CDH1 Mutation Distribution and Type Suggests Genetic Differences between the Etiology of Orofacial Clefting and Gastric Cancer

Pathogenic variants in CDH1, encoding epithelial cadherin (E-cadherin), have been implicated in hereditary diffuse gastric cancer (HDGC), lobular breast cancer, and both syndromic and non-syndromic cleft lip/palate (CL/P). Despite the large number of CDH1 mutations described, the nature of the phenotypic consequence of such mutations is currently not able to be predicted, creating significant challenges for genetic counselling. This study collates the phenotype and molecular data for available CDH1 variants that have been classified, using the American College of Medical Genetics and Genomics criteria, as at least ‘likely pathogenic’, and correlates their molecular and structural characteristics to phenotype. We demonstrate that CDH1 variant type and location differ between HDGC and CL/P, and that there is clustering of CL/P variants within linker regions between the extracellular domains of the cadherin protein. While these differences do not provide for exact prediction of the phenotype for a given mutation, they may contribute to more accurate assessments of risk for HDGC or CL/P for individuals with specific CDH1 variants.

[Hereditary gastric cancer: Challenges for the pathologist in 2020]

Gastric cancer is the third most common cancer worldwide. The majority of gastric cancers are sporadic but familial clustering is seen in more than 10% of cases. This manuscript is divided into two parts. The first part is dedicated to the non-syndromic hereditary gastric cancer, particularly the hereditary diffuse gastric cancer (HDGC) and other gastric polyposes including the recently described GAPPS (Gastric adenocarcinoma and proximal polyposis of the stomach). The second part concerns the syndromic gastric cancer, namely the HNPCC syndrome (Hereditary Non Polyposis Colorectal Cancer) occurring as part of a genetic predisposition syndrome to cancer. Recent advances in oncogenetics and next generation sequencing technology have enabled the identification of new entities. This enhancement in knowledge regarding inherited syndromes predisposing to gastric cancer has consequently improved the management of patients and their families. In this context, pathologists play a major role in identifying particular morphologic entities prompting genetic investigation. The aim of this manuscript is to provide an update on the current knowledge about hereditary gastric cancer.

CD2AP inhibits metastasis in gastric cancer by promoting cellular adhesion and cytoskeleton assembly

Diffuse gastric cancer (DGC) is a lethal malignancy lacking effective systemic therapy. Among the most provocative recent results in DGC has been that the alter of the cellular cytoskeleton and intercellular adhesion. CD2‐associated protein (CD2AP) is one of the critical proteins regulating cytoskeleton assembly and intercellular adhesion. However, no study has investigated the expression and biological significance of CD2AP in gastric cancer (GC) to date. Therefore, the aim of our study was to explore if the expression of CD2AP is associated with any clinical features of GC and to elucidate the underlying mechanism. Immunohistochemistry of 620 patient tissue samples indicated that the expression of CD2AP is downregulated in DGC. Moreover, a low CD2AP level was indicative of poor patient prognosis. In vitro, forced expression of CD2AP caused a significant decrease in the migration and invasion of GC cells, whereas depletion of CD2AP had the opposite effect. Immunofluorescence analysis indicated that CD2AP promoted cellular adhesion and influenced cell cytoskeleton assembly via interaction with the F‐actin capping protein CAPZA1. Overall, the upregulation of CD2AP could attenuate GC metastasis, suggesting CD2AP as a novel biomarker for the prognosis and treatment of patients with GC.

Chronic atrophic gastritis and intestinal metaplasia surrounding diffuse-type gastric cancer: Are they just bystanders in the process of carcinogenesis?

BACKGROUND

Gastric cancer (GC) is categorized as diffuse- and intestinal-type adenocarcinoma. Intestinal-type GC is associated with chronic gastritis, atrophic gastritis (AG), and intestinal metaplasia (IM), precursors of dysplastic changes. Diffuse-type GC is generally known to undergo de novo carcinogenesis and is not associated with chronic mucosal changes. However, clinically, AG and IM are frequently observed surrounding diffuse-type GC. This study aimed to evaluate the role of AG and IM in diffuse-type GC.

METHODS

We retrospectively reviewed the data of patients undergoing surgery for early GC. We divided patients with diffuse-type GC into two groups according to the presence of AG and IM based on Kyoto classification of gastritis. The clinicopathological characteristics were compared between the groups.

RESULTS

Among patients with diffuse-type GC, 52.5% patients had AG and 18.4% had severe AG. With regard to IM, 42.1% patients had IM and 17.1% had severe IM. Diffuse-type GC combined with severe AG or IM showed larger tumor size and higher submucosal invasion rate than that without severe AG or IM. However, the lymph node metastasis (LNM) rate was not significantly different between the two groups. In multivariate analysis, severe AG or IM was not an independent risk factor for LNM.

CONCLUSIONS

Severe AG or IM surrounding diffuse-type gastric cancer suggests a collapse of normal mucosal barriers and leads to the spread of cancer cells. Although the association between chronic mucosal changes and LNM is unclear, more caution is needed during endoscopy especially for complete resection of diffuse-type GC with these features.

CDH1 (E-Cadherin) Mutation and Gastric Cancer: Genetics, Molecular Mechanisms and Guidelines for Management

Introduction

Germline mutation in CDH1 (E-cadherin) tumor suppressor gene is associated with hereditary diffuse gastric cancer (HDGC) and lobular breast cancers (LBC). E-Cadherin protein is necessary for physiological signaling pathways, such as cell proliferation, maintenance of cell adhesion, cell polarity and epithelial-mesenchymal transition. Dysregulation leads to tumor proliferation, invasion, migration and metastases. We review current perspectives in CDH1 genetics with molecular mechanisms and also discuss management strategies for this aggressive form of gastric cancer.

Methods

Relevant articles from PubMed/Medline and Embase (1994–2019) were searched and collected using the phrases “Hereditary diffuse gastric cancer, Familial gastric cancer, CDH1 mutation, E-Cadherin, Lobular breast cancer, Prophylactic total gastrectomy”.

Results

Current guidelines suggest maintaining a high degree of suspicion of hereditary etiology and recommend testing for CDH1 mutations in patients with familial clustering of HDGC and LBC, especially onset at an early age (before 40 years). In families lacking CDH1 mutations but with high suspicion for hereditary predisposition, testing of CTNNA1 and other closely related HDGC susceptibility genes could be considered. Prophylactic total gastrectomy is recommended for individuals with identified pathogenic germline variants. Endoscopic surveillance with biopsies is recommended for those choosing to delay prophylactic gastrectomy.

Conclusion

Mutation or transcriptional silencing of the CDH1 gene is associated with familial diffuse gastric cancer. Further studies on the expression and the alteration in the proteins in the E-cadherin pathways may serve as biomarkers for early detection; stratify risk and selection of appropriate therapy in these families. Until then prophylactic total gastrectomy is recommended for individuals with CDH1 mutations and family history of diffuse gastric cancer. Endoscopic surveillance and biopsies by experienced gastroenterologists is recommended for those choosing not to have prophylactic gastrectomy and in individuals with CDH1 variants.

Hereditary gastric cancer: what's new? Update 2013-2018

Around 10-20% of gastric cancer patients have relatives with a diagnosis of GC and in 1-3% of patients a genetic cause can be confirmed. Histopathologically, GC is classified into intestinal-type, with glandular growth, and diffuse-type with poorly cohesive growth pattern often with signet ring cells. Familial or hereditary GC is classified into hereditary diffuse GC (HDGC), familial intestinal GC (FIGC) and polyposis forms. This review focuses on recent research findings and new concepts of hereditary GC.

Effects of high progesterone in in-vitro fertilization cycle on DNA methylation and gene expression of adhesion molecules on endometrium during implantation window

PURPOSE

High progesterone is associated with low implantation rate. Our previous study demonstrated that DNA methylation in endometrium was increased in women with high progesterone in IVF cycles. However, the DNA methylation status is still not yet confirmed, and how it affects endometrial receptivity in high progesterone is still unknown. Current study investigated the effects of high progesterone on DNA methylation and gene expression of adhesion molecules on endometrium during implantation window.

METHODS

A cohort study included 20 women with high progesterone (HP) and 20 with normal progesterone (NP) on the day of human chorionic gonadotropin (hCG) administration after controlled ovarian hyperstimulation in IVF cycle. Endometrial tissues were collected on the 7th day after hCG administration. Immunohistochemical staining of DNA methyltransferases (DNMT1 and DNMT3B) and adhesion molecules (MUC1, CDH1 and CTNNB1) were performed. Methylation of MUC1, CDH1, and CTNNB1 promoter regions was detected by Sequenom MassARRAY or bisulfite sequencing PCR. RT-qPCR was used to quantify mRNA expression levels, and correlation of methylation and gene expression level of the adhesion molecules were determined.

RESULTS

DNMT3B, but not DNMT1, in nucleus of luminal and glandular epithelial cells in HP group was significantly higher than that in NP group. Promoter regions of CDH1 and CTNNB1, but not MUC1, in endometrium of HP group were hypermethylated. Protein and mRNA expression of MUC1, CDH1, and CTNNB1 in endometrium of HP group was significantly lower than that in NP group. Level of DNA methylation was negatively correlated with the gene expression of CDH1 and CTNNB1, but not MUC1.

CONCLUSIONS

DNA hypermethylation and low expression of adhesion molecules on endometrium were associated with high progesterone during implantation window, which may contribute to the underlying epigenetic mechanism in the failure of IVF treatment.

A panel of DNA methylated markers predicts metastasis of pN0M0 gastric carcinoma: a prospective cohort study

BACKGROUND

The aim of this prospective study was to evaluate the feasibility of predicting GC metastasis using CDH1, GFRA1, P16 and ZNF382 DNA methylation as biomarkers.

METHODS

198 GC patients without metastasis at the time of surgery resection were recruited into the double-blind cohort (NCT02159339). Gene methylation was analysed using MethyLight assays. GC metastasis and survival data were obtained from 178 patients with 94.7% compliance during follow-up.

RESULTS

Twenty six cases of metastasis and 5 cases of recurrence were observed in 178 cases (17.4%) during the follow-up (median, 62.7 months). The GC metastasis rate for GFRA1 methylation-positive patients was significantly reduced compared with GFRA1 methylation-negative patients (odds ratio [OR]: 0.23, 95% confidence interval [CI] 0.08-0.66). Similar results were also observed using ZNF382 methylation as a predictor (OR: 0.17, 95% CI 0.06-0.47). A risk score including methylation of GFRA1 and ZNF382 was generated. The metastasis rate was significantly increased in high-risk GC patients (OR: 4.71, 95% CI: 1.85-12.00). GC patients with high risk had a shorter overall survival, especially for patients with stage I GC (P = 0.024).

CONCLUSIONS

The combination of GFRA1 and ZNF382 methylation is a biomarker panel for the prediction of GC metastasis.

Non-coding RNAs in regulating gastric cancer metastasis

Gastric cancer is one of the leading causes of cancer-related deaths worldwide, and mortality remains high, especially in East Asia. At present, the main method to diagnose gastric cancer is pathological biopsy. At the time of diagnosis, most patients have been diagnosed with advanced cancer and metastasis. The treatment of gastric cancer patients is mainly radical surgical resection and chemoradiotherapy, while patients with metastatic tumor have great challenges to radical surgery and are prone to drug resistance. Metastasis is an important factor affecting tumor development. In addition, evidence accumulated in the literature indicates that non-coding RNA plays a key role in tumor metastasis. This article reviews the role of ncRNAs in gastric cancer metastasis and discusses the regulatory mechanism in the development and treatment of gastric cancer.

A new mutL homolog 1 c.1896+5G>A germline mutation detected in a Lynch syndrome-associated lung and gastric double primary cancer patient

BACKGROUND

Mismatch-repair genes (MMRs) ensure high fidelity in genome editing. Loss of function mutation of MMRs will lead to instability of the genome and increase the incidence of cancers. Human mutL homolog 1 (MLH1) is a member of the MMRs, and its mutation is found in Lynch syndrome (LS). In addition to the high incidence of colorectal cancer, LS patients often have other primary cancers. Here, a case of LS-associated lung and gastric double primary cancer was reported.

METHODS

Diagnosis of lung and gastric double primary cancer was mainly based on clinical findings, imaging examination, and histopathological data. The tumor tissues and blood samples were collected, and then genomic DNA was extracted and 450 cancer-related gene alteration screening was conducted by next-generation sequencing and the functional verification of a mutant gene was carried out using the PCR method.

RESULTS

We detected the epidermal growth factor receptor L858R, MSH2 R929* and telomerase reverse transcriptase amplification in the lung cancer specimen; CDH1 c.1320+1G>T mutation in the gastric cancer (GC) specimen; and MLH1 c.1896+5G>A germline mutation in the lung and GC specimens by 450 cancer-related gene mutations detection using next-generation sequencing technology. MLH1c.1896+5G>A is a novel germline mutation, and it was verified by the PCR subsequently. It was found that it could affect the splicing of intron 16. Nine relatives of three-generation of the patient were examined and the MLH1 c.1896+5G>A mutation and pedigree analysis were performed. The father's sister without cancer also carries this mutation.

CONCLUSION

Diagnosis of LS was mainly depended on the following: the cancer histories of his relatives, multi-primary cancers of lung and stomach in his own body, MLH1 and MSH2 gene mutations detected in the cancer tissues. The clinical significance of this new MLH1 c.1896+5G>A germline mutation detected in the LS-associated double primary cancer patient needed further study.

Identifying DNA methylation biomarkers for non-endoscopic detection of Barrett's esophagus

We report a biomarker-based non-endoscopic method for detecting Barrett's esophagus (BE) based on detecting methylated DNAs retrieved via a swallowable balloon-based esophageal sampling device. BE is the precursor of, and a major recognized risk factor for, developing esophageal adenocarcinoma. Endoscopy, the current standard for BE detection, is not cost-effective for population screening. We performed genome-wide screening to ascertain regions targeted for recurrent aberrant cytosine methylation in BE, identifying high-frequency methylation within the CCNA1 locus. We tested CCNA1 DNA methylation as a BE biomarker in cytology brushings of the distal esophagus from 173 individuals with or without BE. CCNA1 DNA methylation demonstrated an area under the curve of 0.95 for discriminating BE-related metaplasia and neoplasia cases versus normal individuals, performing identically to methylation of VIM DNA, an established BE biomarker. When combined, the resulting two biomarker panel was 95% sensitive and 91% specific. These results were replicated in an independent validation cohort of 149 individuals who were assayed using the same cutoff values for test positivity established in the training population. To progress toward non-endoscopic esophageal screening, we engineered a well-tolerated, swallowable, encapsulated balloon device able to selectively sample the distal esophagus within 5 min. In balloon samples from 86 individuals, tests of CCNA1 plus VIM DNA methylation detected BE metaplasia with 90.3% sensitivity and 91.7% specificity. Combining the balloon sampling device with molecular assays of CCNA1 plus VIM DNA methylation enables an efficient, well-tolerated, sensitive, and specific method of screening at-risk populations for BE.

RHOA mutations and CLDN18-ARHGAP fusions in intestinal-type adenocarcinoma with anastomosing glands of the stomach

A subtype of intestinal-type adenocarcinoma of the stomach, characterized by low-grade cytological atypia and anastomosing glands, has been described in several reports under different names. One of the remarkable features of these lesions, herein referred to as intestinal-type adenocarcinoma with anastomosing glands, is the frequent association of poorly differentiated adenocarcinoma components. Here we analyzed 44 intestinal-type adenocarcinomas with anastomosing glands focusing on the molecular abnormalities that are common in diffuse-type gastric cancers. Next-generation sequencing identified RHOA and CDH1 mutations in 22 (50%) and one lesion (2%), respectively. Reverse transcription-PCR detected CLDN18-ARHGAP fusions in three lesions (7%). Immunohistochemically, none of the lesions showed abnormal p53 expression patterns whereas focal and diffuse loss of ARID1A was observed in four and one lesion, respectively. Examination of 37 lesions of dysplasia and 26 usual-type intramucosal adenocarcinomas identified one RHOA mutation in adenocarcinoma and no CLDN18-ARHGAP fusions, indicating that these genetic alterations are highly specific to intestinal-type adenocarcinomas with anastomosing glands among differentiated-type intramucosal neoplasms. The present study showed that intestinal-type adenocarcinoma with anastomosing glands represents a genetically distinct group of tumors with the frequent presence of RHOA mutations and CLDN18-ARHGAP fusions, which are thought to be specific to diffuse-type gastric cancers.