A comprehensive analysis of common genetic variation in MUC1, MUC5AC, MUC6 genes and risk of stomach cancer. Cancer Causes Control. 2010;21:313-321. [PMID: 19924550 DOI: 10.1007/s10552-009-9463-3]

Association between MUC1 rs4072037 polymorphism and Helicobacter pylori in patients with gastric cancer

Background

The MUC1 gene encodes glycoproteins attached to cell membrane that play a protective role in gastric cancer and protect epithelial surfaces against external factors such as Helicobacter pylori. H. pylori infection can induce a cascade of innate and acquired immune responses in gastric mucosa. Relationship between rs4072037G>A polymorphism of MUC1 gene and increased susceptibility to H. pylori infection aimed to investigate in patients with gastric cancer in Mazandaran, northern Iran.

Methods

A case-control study was conducted on 99 patients with gastric cancer (H. pylori positive and negative) and 98 controls (H. pylori positive and negative) without gastric cancer (confirmed by pathological biopsy samples obtained during endoscopy). H. pylori infection was diagnosed by histological examination using Giemsa staining. Genomic DNA extracted from peripheral blood was analyzed by PCR-RFLP technique.

Results

Analysis of all genetic models showed no significant relationship between rs4072037G>A polymorphism and risk of gastric cancer (GC). The relationship between H. pylori infection and rs4072037G>A polymorphism showed an increased susceptibility to gastric cancer in both positive and negative H. pylori groups (including case and control groups). The genetic model of GA/GG and H. pylori- positive versus GA/GG and H. pylori-negative showed a significantly increased susceptibility to gastric cancer (OR=0.251, CI: 0.128-0.493, P=0.000).

Conclusion

These findings indicate that rs4072037G>A polymorphism may interact with H. pylori infection to increase the risk of GC.

The Role of Mucin Expression in the Diagnosis of Oesophago-Gastric Cancer: A Systematic Literature Review

Survival in oesophago-gastric cancer (OGC) is poor due to early diagnostic challenges. Non-invasive risk stratification may identify susceptible patients with pre-malignant or benign disease. Following diagnostic confirmation with endoscopic biopsy, early OGC may be treated sooner. Mucins are transmembrane glycoproteins implicated in OGC with potential use as biomarkers of malignant transformation. This systematic review defines the role of mucins in OGC diagnosis. A literature search of MEDLINE, Web of Science, Embase and Cochrane databases was performed following PRISMA protocols for studies published January 1960-December 2022. Demographic data and data on mucin sampling and analysis methods were extracted. The review included 124 studies (n = 11,386 patients). Gastric adenocarcinoma (GAc) was the commonest OG malignancy (n = 101) followed by oesophageal adenocarcinoma (OAc, n = 24) and squamous cell carcinoma (OSqCc, n = 10). Mucins MUC1, MUC2, MUC5AC and MUC6 were the most frequently implicated. High MUC1 expression correlated with poorer prognosis and metastases in OSqCc. MUC2 expression decreases during progression from healthy mucosa to OAc, causing reduced protection from gastric acid. MUC5AC was upregulated, and MUC6 downregulated in GAc. Mucin expression varies in OGC; changes may be epigenetic or mutational. Profiling upper GI mucin expression in OGC, with pre-malignant, benign and healthy controls may identify potential early diagnostic biomarkers.

A Model for Gastric Cancer Risk Prediction Based on MUC1 Polymorphisms and Health-risk Behaviors in a Vietnamese Population

BACKGROUND/AIM

Although the expression of mucin 1(MUC1) and prostate stem cell antigen (PSCA) genes is correlated with gastric cancer development and progression, the utility of these two genes as biomarkers of gastric cancer prognosis still needs to be confirmed in clinical practice. This study aimed to develop a model predictive of gastric cancer that integrates several significant single nucleotide polymorphisms (SNPs) of MUC1 and PSCA genes, and some health-risk behavior factors in a Vietnamese population.

PATIENTS AND METHODS

A total of 302 patients with primary gastric carcinoma and 304 healthy persons were included in a case-control study. The generalized linear model was used with the profile of age, sex, history of smoking and using alcohol, personal and family medical history of stomach diseases, and the SNPs of MUC1 and PSCA. The prognostic value of the model was assessed by the area under a receiver operating characteristic curve (AUC) and Akaike Information Criterion (AIC) values.

RESULTS

In male participants, the final model, consisting of age, sex, history of smoking and using alcohol, personal and family medical history of stomach diseases and SNP MUC1 rs4072037, provided acceptable discrimination, with an AUC of 0.6374 and the lowest AIC value (539.53). In female participants, the predictive model including age, sex, history of smoking and using alcohol, personal and family medical history of stomach diseases, SNPs MUC1 rs4072037 and rs2070803 had an AUC of 0.6937 and AIC of 266.80. The calibration plots of the male model approximately fitted the ideal calibration line.

CONCLUSION

The predictive model based on age, sex, medical history, and genetic and health-risk behavior factors has a high potential in determining gastric cancer. Further studies that elucidate other genetic variants should be carried out to define high-risk gastric cancer groups and propose appropriate personalized prevention.

Genome-wide association study for single nucleotide polymorphism associated with mural and cumulus granulosa cells of PCOS (polycystic ovary syndrome) and non-PCOS patients

Background

The genetic make-up of local granulosa cells and their function in the pathophysiology of polycystic ovary syndrome (PCOS) is crucial to a full comprehension of the disorder. The major purpose of this study was to compare the Single Nucleotide Polymorphism (SNP) of cumulus granulosa cells (CGCs) and mural granulosa cells (MGCs) between healthy individuals and women with PCOS using genome-wide association analysis (GWA). A case–control study was conducted in a total of 24 women diagnosed with PCOS and 24 healthy non-PCOS women of reproductive age aggregated into 4 samples of 6 patients each. GWA studies entail several processes, such as cell separation, cellular DNA extraction, library preparation followed by interpretation using bioinformatics databases. SNP locations were identified by reference gene also involves the use of Matrix-assisted laser desorption/ionisation-time of flight (MALDI-TOF) mass spectrometry (MS) (MALDI-TOF-MS) for the first sorting. Hybridization with the gene chip was followed by reading the SNP genotypes according to the publications in the literature. TASSEL (Trait Analysis by aSSociation, Evolution and Linkage) program and methods were used for GWA studies.

Results

An aggregate of 21,039 SNP calls were obtained from our samples. Genes of autoimmune illnesses, obesity, inflammatory illnesses, nervous system diseases such as retinitis pigmentosa, autism, neural tube defects, and Alzheimer's disease; and various malignancies such as lung cancer, colorectal cancer, breast cancer were also identified in these cells. Gene ranking score reveals that granulosa cells carry key genes of neurological system and reproductive systems especially in brain and testis, respectively.

Conclusions

Mural and Cumulus Granulosa cells were shown to have the PCOS directly and indirectly related genes MMP9, PRKAA2, COMT and HP. We found that the expression of ARID4B, MUC5AC, NID2, CREBBP, GNB1, KIF2C, COL18A1, and HNRNPC by these cells may contribute to PCOS.

Graphical abstract

Mucin (MUC) Family Influence on Acute Lymphoblastic Leukemia in Cancer and Non-Cancer Native American Populations from the Brazilian Amazon

The mucin (MUC) family includes several genes aberrantly expressed in multiple carcinomas and mediates diverse pathways essentials for oncogenesis, in both solid and hematological malignancies. Acute Lymphoblastic Leukemia (ALL) can have its course influenced by genetic variants, and it seems more frequent in the Amerindian population, which has been understudied. Therefore, the present work aimed to investigate the MUC family exome in Amerindian individuals from the Brazilian Amazon, in a sample containing healthy Native Americans (NAMs) and indigenous subjects with ALL, comparing the frequency of polymorphisms between these two groups. The population was composed of 64 Amerindians from the Brazilian Amazon, from 12 different isolated tribes, five of whom were diagnosed with ALL. We analyzed 16 genes from the MUC family and found a total of 1858 variants. We compared the frequency of each variant in the ALL vs. NAM group, which led to 77 variants with a significant difference and, among these, we excluded those with a low impact, resulting in 63 variants, which were distributed in nine genes, concentrated especially in MUC 19 (n = 30) and MUC 3A (n = 18). Finally, 11 new variants were found in the NAM population. This is the first work with a sample of native Americans with cancer, a population which is susceptible to ALL, but remains understudied. The MUC family seems to have an influence on the development of ALL in the Amerindian population and especially MUC19 and MUC3A are shown as possible hotspots. In addition, the 11 new variants found point to the need to have their clinical impact analyzed.

α1,4-linked N-acetylglucosamine suppresses gastric cancer development by inhibiting MUC1-mediated signaling

Gastric cancer is the second leading cause of cancer deaths worldwide, and more understanding of its molecular basis is urgently needed. Gastric gland mucin secreted from pyloric gland cells, mucous neck cells, and cardiac gland cells of the gastric mucosa harbors unique O‐glycans carrying terminal α1,4‐linked N‐acetylglucosamine (αGlcNAc) residues. We previously reported that αGlcNAc loss correlated positively with poor outcomes for patients with differentiated‐type gastric cancer. However, the molecular mechanisms underlying these outcomes remained poorly understood. Here, we examined the effects of upregulated αGlcNAc expression on malignant phenotypes of the differentiated‐type gastric cancer cell lines, AGS and MKN7. Upregulation of αGlcNAc following ectopic expression of its biosynthetic enzyme attenuated cell proliferation, motility, and invasiveness of AGS and MKN7 cells in vitro. Moreover, AGS cell tumorigenicity was significantly suppressed by αGlcNAc overexpression in a xenograft model. To define the molecular mechanisms underlying these phenotypes, we investigated αGlcNAc binding proteins in AGS cells and identified Mucin‐1 (MUC1) and podocalyxin. Both proteins were colocalized with αGlcNAc on human gastric cancer cells. We also found that αGlcNAc was bound to MUC1 in murine normal gastric mucosa. When we assessed the effects of αGlcNAc binding to MUC1, we found that αGlcNAc blocked galectin‐3 binding to MUC1, phosphorylation of the MUC1 C‐terminus, and recruitment of Src and β‐catenin to that C‐terminus. These results suggest that αGlcNAc regulates cancer cell phenotypes by dampening MUC1 signal transduction.

Integrative omics analysis reveals the protective role of vitamin C on perfluorooctanoic acid-induced hepatoxicity

Introduction

Perfluorooctanoic acid (PFOA) is a compound used as an industrial surfactant in chemical processes worldwide. Population and cross-sectional studies have demonstrated positive correlations between PFOA levels and human health problems.

Objectives

Many studies have focused on the hepatotoxicity and liver problems caused by PFOA, with little attention to remediation of these problems. As an antioxidant, vitamin C is frequently utilized as a supplement for hepatic detoxification.

Methods

In this study, we use a mouse model to study the possible role of vitamin C in reducing PFOA-induced liver damage. Based on comparative transcriptomic and metabolomic analysis, we elucidate the mechanisms underlying the protective effect of vitamin C.

Results

Our results show that vitamin C supplementation reduces signs of PFOA-induced liver damage including total cholesterol and triglyceride levels increase, liver damage markers aspartate, transaminase, and alanine aminotransferase elevation, and liver enlargement. Further, we show that the protective role of vitamin C is associated with signaling networks control, suppressing linoleic acid metabolism, reducing thiodiglycolic acid, and elevating glutathione in the liver.

Conclusion

The findings in this study demonstrate, for the first time, the utility of vitamin C for preventing PFOA-induced hepatotoxicity.

Regulation of MUC6 Methylation Correlates with Progression of Gastric Cancer

PURPOSE

This study aimed to investigate the mechanistic downregulation of mucin 6 (MUC6) and its influence on the progression of gastric cancer (GC).

MATERIALS AND METHODS

The expression of MUC6 was examined in 40 GC patients. The methylation status of the MUC6 promoter region was investigated using GC cell lines and GC tissue specimens by immunohistochemistry and/or quantitative polymerase chain reaction (qPCR). MUC6 was knocked down in the gastric epithelial cells (GES-1) cell and overexpressed in the SGC7901 cell. The effects of MUC6 knockdown and overexpression on cell migration and invasion were examined using Transwell assays. The effects of demethylation and methylation on MUC6 expression were examined by western blot, qPCR, or double luciferase reporter assays.

RESULTS

The expression of MUC6 in GC with lymph node metastasis and poor pathological stage was significantly lower than that in GC without lymph node metastasis and good pathological stage, respectively. While cell migration and invasion were significantly decreased after overexpression of MUC6, these abilities significantly increased after the knockdown of MUC6. The methylation levels of MUC6 in GC tissues and GC cell lines were significantly higher than those in para-cancerous tissues and normal GES. Promoter methylation could significantly reduce the binding of related transcription factors to the MUC6 promoter. The expression of MUC6 increased with the concentration and time of action of demethylation drugs.

CONCLUSION

Expression of MUC6 was regulated by promotor methylation. This methylation of the MUC6 promoter may lead to significant downregulation of MUC6 in GC and promote the progression of GC.

Polymorphism of MUC1 Gene in Vietnamese Gastric Cancer Patients: A Multicenter Case-Control Study

Background

A few studies revealed that the polymorphisms of Mucin 1 gene have a role and significance as a susceptible factor contributing to gastric cancer. To better understand the roles of two MUC1 genotype polymorphisms of rs4072037 and rs2070803 in the development of gastric cancer in Vietnamese population, a multicenter, large-sample, case-control study was conducted to investigate the potential association of these single-nucleotide polymorphisms (SNPs) of MUC1 gene with gastric cancer risk and to evaluate the combination factors in relation with these SNPs.

Methods

This case-control study included 302 gastric cancer patients and 304 controls at four national medical hospitals between 2016 and 2018. All participants were interviewed for sociodemographic characteristics, smoking and drinking status, and personal and family history of gastric diseases. Genotyping was done using polymerase chain reaction-restriction fragment length polymorphism analysis. The association of SNPs with gastric cancer was explored using logistic regression models.

Results

AA genotype for rs4072037 was significantly associated with increased gastric cancer. Those with AA genotype had higher gastric cancer risk than had patients with AG (OR: 2.09, 95% CI: 1.48-2.96) and a combination of AG+GG (OR: 1.85, 95% CI: 1.33-2.56). In rs2070803, GG genotype increased gastric cancer risk when compared with AG (OR: 1.97, 95% CI: 1.39-2.80) and AG+AA (OR: 1.71, 95% CI: 1.23-2.39). AG genotypes in both SNPs decreased gastric cancer risk when compared with homogenous genotype, more specifically AA (OR: 0.51, 95% CI: 0.35-0.72) and GG (OR: 0.58, 95% CI: 0.35-0.97). These genotypes in combination with above-60-year-old age, male gender, alcoholism, and personal history of gastric disease were also significantly elevated risk factors for gastric cancer.

Conclusions

rs4072037 and rs2070803 of Mucin 1 genes are two genotypic risk factors for gastric cancer. Those in combination with gender, family history, smoking, and drinking habits significantly increase the risk of gastric cancer.

Human genomics of the humoral immune response against polyomaviruses

Human polyomaviruses are widespread in humans and can cause severe disease in immunocompromised individuals. To identify human genetic determinants of the humoral immune response against polyomaviruses, we performed genome-wide association studies and meta-analyses of qualitative and quantitative immunoglobulin G responses against BK polyomavirus (BKPyV), JC polyomavirus (JCPyV), Merkel cellpolyomavirus (MCPyV), WU polyomavirus (WUPyV), and human polyomavirus 6 (HPyV6) in 15,660 individuals of European ancestry from three independent studies. We observed significant associations for all tested viruses: JCPyV, HPyV6, and MCPyV associated with human leukocyte antigen class II variation, BKPyV and JCPyV with variants in FUT2, responsible for secretor status, MCPyV with variants in STING1, involved in interferon induction, and WUPyV with a functional variant in MUC1, previously associated with risk for gastric cancer. These results provide insights into the genetic control of a family of very prevalent human viruses, highlighting genes and pathways that play a modulating role in human humoral immunity.

MUC1 and MUC5AC implication in Tunisian colorectal cancer patients

Background/aim

Mucins, such as MUC1 and MUC5AC, are known for their protective and moisturizing role in intestinal epithelium. Their expression is tightly controlled given their essential role in normal tissue homeostasis, whereas their deregulation leads to chronic inflammation, and even cancer. This study aimed to assess the expression profiles of MUC1 and MUC5AC and their implications in colorectal carcinogenesis.

Materials and methods

A retrospective study of 202 patients who underwent colorectal cancer (CRC) surgery was conducted. The expression of MUC1 and MUC5AC was investigated by immunohistochemistry and reverse-transcription polymerase chain reaction (RT-PCR). Statistical analysis of mucin expression pattern, as well as the clinicopathological criteria of the patients, was performed using the chi-square test, survival curves were plotted using the Kaplan—Meier product-limit method, and differences between the survival curves were tested using the log-rank test.

Results

The expression of both mucins was abnormally high in the tumor tissues for both mRNA and protein. MUC1 expression was correlated with advanced cancer stages and lymph node metastases for both the mRNA (P < 0.016 and P < 0.002, respectively) and protein level (P < 0.006 and P < 0.001, respectively). However, MUC5AC expression did not pinpoint any significant association between the clinicopathological criteria, but patients who expressed MUC5AC showed an increase in overall survival (P < 0.009).

Conclusion

The expression of MUC1 might be a poor prognostic biomarker in CRC and could play a role in tumor transformation and metastasis. However, MUC5AC expression might be a good prognostic in the Tunisian cohort.

Gastric cancer: epidemiology, biology, and prevention: a mini review

Gastric cancer is one of the most common causes of cancer-related mortality worldwide. The objective of this article is to review the epidemiology and biology of gastric cancer risk. This literature review explores the biological, clinical, and environmental factors that influence the rates of this disease and discuss the different intervention methods that may not only increase the awareness of gastric cancer but also increase screening in efforts to reduce the risk of gastric cancer. Helicobacter pylori infection is the primary risk factor for gastric cancer. Additional risk factors include geographical location, age, sex, smoking, socioeconomic status, dietary intake, and genetics. Primary and secondary prevention strategies such as dietary modifications and screenings are important measures for reducing the risk of gastric cancer. Interventions, such as H. pylori eradication through chemoprevention trials, have shown some potential as a preventative strategy. Although knowledge about gastric cancer risk has greatly increased, future research is warranted on the differentiation of gastric cancer epidemiology by subsite and exploring the interactions between H. pylori infection, genetics, and environmental factors. Better understanding of these relationships can help researchers determine the most effective intervention strategies for reducing the risk of this disease.

Association between the MUC1 rs4072037 Polymorphism and Risk of Gastric Cancer and Clinical Outcomes

Purpose

Mucin 1 (MUC1) was identified as a gastric cancer (GC) susceptibility gene by genome-wide association studies in Asians and candidate gene studies in Europeans. This study aimed to investigate the association between the MUC1 rs4072037 polymorphism and GC in terms of the Lauren classification and long-term clinical outcomes.

Materials and Methods

A total of 803 patients with GC and 816 unrelated healthy controls were enrolled in the study. The association between the MUC1 rs4072037 variant and GC histological types and clinical outcomes, including tumor recurrence and prognosis was investigated.

Results

The major A allele of rs4072037 was associated with increased GC risk (P<0.05). In subtype analysis, the association was most significant for diffuse-type GC (P<0.05) and in a dominant model (P<0.05), whereas there was no association with intestinal-type GC (P>0.05). Cox proportional hazards analysis revealed the heterozygote AG rs4072037 allele as an independent risk factor influencing tumor recurrence and disease-related death in diffuse-type GC (P<0.05). but not in intestinal-type GC (P>0.05).

Conclusions

The exonic single nucleotide polymorphism rs4072037 in MUC1 was associated with diffuse-type GC and was an independent risk factor influencing tumor recurrence and disease-related death in diffuse-type GC.

MUC1 is associated with TFF2 methylation in gastric cancer

Background

Emerging evidence has shown that MUC1 and TFF2 play crucial roles in the H. pylori-infected pathogenesis of gastric cancer (GC). A recent study revealed that H. pylori infection induced obviously increased Tff2 methylation levels in Muc1^−/− mice compared with controls. However, little is known of the molecular mechanism on MUC1 regulating the expression of TFF2.

Methods

We conducted a correlation analysis of MUC1 and TFF2 in public databases and our adjacent GC tissues. Besides, MUC1 overexpression vector or small interfering RNA (siRNA) was transfected into GC cells to assess the change in TFF2 expression. Furthermore, the methylation status of TFF2 was measured by bisulfite sequencing PCR (BSP).

Results

The expression of MUC1 was significantly lower in non-cardia and cardia tumor tissues than that in normal tissues. Downregulation of TFF2 expression was also observed in GC tissues. In addition, we found that MUC1 expression was positively associated with TFF2 expression in GC tissues, especially among GC patients with H. pylori infection. Overexpression of MUC1 in BGC-823 and SGC-7901 cell lines substantially increased the TFF2 expression, whereas knockdown of MUC1 reverted this effect. Moreover, MUC1 was negatively related to the methylation of TFF2 in the co-expression analysis. The results of BSP experiments showed that compared with negative vector group, the methylation level of TFF2 was decreased in GC cells transfected with MUC1 overexpression vector. Additionally, survival analysis indicated that GC patients with lower level of MUC1 or TFF2 had a worse outcome.

Conclusion

Our results indicated that MUC1 was associated with the methylation of TFF2, which may have implications for TFF2 expression in GC. These findings warrant further research toward the underlying mechanism of MUC1 influenced the TFF2 methylation.

Role of MUC1 rs4072037 polymorphism in gastric cancer: a meta-analysis

Background and objective: To further determine the association between mucin 1 (MUC1) rs4072037 polymorphism and gastric cancer risk on the basis of previously published studies. Methodology: PubMed and Embase were used to search all the available publications. The relative risk of the correlation was shown as odds ratio (OR) with 95% confidence interval (95% CI) under all the genetic comparisons. Subgroup analyses based on ethnicity, study design and HWE were also executed to detect effects of specific factors on the risk of gastric cancer. Results: MUC1 rs4072037 polymorphism was observed to reduce the risk of gastric cancer under the five genetic comparisons [(GG versus AA: OR (95% CI)=0.72 (0.61, 0.84); GG + GA versus AA: OR (95% CI)=0.82 (0.76, 0.88); GG versus AA + GA: OR (95% CI)=0.83 (0.71, 0.96); G versus A: OR (95% CI)=0.78 (0.72, 0.84); GA versus AA: OR (95% CI)=0.80 (0.74, 0.87)]. This decreased risk of gastric cancer was also detected in subgroup analyses based on ancestry (Asian and Caucasian), study design (population-based and hospital-based) and HWE (P _HWE>0.05). Conclusions: MUC1 rs4072037 polymorphism may have an important role in gastric cancer, and this protective effect may vary among different ethnic populations and control subjects.

Screening and Survival Analysis of Hub Genes in Gastric Cancer Based on Bioinformatics

Screening for hub genes associated with gastric cancer and elucidating possible molecular mechanisms of gastric cancer. Five gastric cancer-related gene expression profiles were extracted from the GEO database, and differentially expressed genes (DEGs) were obtained using GEO2R. Gene ontology (GO) enrichment analyses were performed by DAVID, and protein-protein interaction (PPI) network of the DEGs was constructed by STRING and Cytoscape software. Survival value for hub gene comes from the Kaplan-Meier plotter platform. In addition, potential miRNAs of hub genes were predicted by miRWalk. Four hundred seventy-six DEGs were identified in the five expression profiles, these genes are mainly involved in extracellular matrix (ECM)-receptor interaction, chemical carcinogenesis, gastric acid secretion, and PI3K-Akt signaling pathway. Combined with the results of the PPI network and CytoHubba, six hub genes were screened: SERPINH1, NPY, PTGDR, GPER, ADHFE1, and AKR1C1. These genes are highly expressed in gastric cancer tissues, and the overexpression level of these genes is associated with poor survival. A series of miRNAs such as hsa-miRNA-92a-1, hsa-miRNA-647, and hsa-miRNA-507 may play a key role in hub gene regulation. Our studies indicate that SERPINH1, NPY, PTGDR, GPER, ADHFE1, and AKR1C1 may be potential biomarkers and therapeutic targets for gastric cancer in the future.

Identification of a low frequency missense mutation in MUC6 contributing to pulmonary artery hypertension by whole-exome sequencing

Pulmonary arterial hypertension (PAH) represents a progressive disease characterized by abnormally high blood pressure in the pulmonary artery. Although mutations in the bone morphogenetic receptor 2 (BMPR2) are found in 80% of heritable, their low penetrance suggests that other unidentified genetic modifiers are required for this disease. In this report, whole-exome sequencing (WES) and a linkage analysis were performed on genomic DNA isolated from four affected relatives and one non-affected relative in two PAH families. By focusing on meaningful variants which were presented in the four affected family members, but not presented in the non-affected individual, 49 SNP and eight indel variants in 39 genes were identified as candidates. Further high-throughput multiplex genotyping and Sanger sequencing were carried out to confirm the putative causal mutations in 150 individuals (30 idiopathic PAH [IPAH] patients, 30 chronic thromboembolic pulmonary hypertension [CTEPH] patients, and 90 normal controls). A heterozygous and deleterious mutation in the gene MUC6 (p.Pro1716Ser) was confirmed in the IPAH group (20/30, 67%) and CTEPH group (1/30, 3.33%); no variant was detected in the 90 normal controls. MUC6, which is short for mucin 6, encodes high molecular weight glycoprotein produced by many epithelial tissues and forms an insoluble mucous barrier that protects the lumens. We re-confirmed this low frequency mutation with the 1000 Genomes database across all species; no population or frequency data of this allele were acquired. We also found that this mutation site was highly conserved in different species and predicted MUC6 has the protection function of the airway and pneumoangiogram based on genomic sequence data. The compound heterozygous MUC6 gene mutation (p.Pro1716Ser) suggests a novel disease mechanism leading to PAH.

Transfection of the Helicobacter pylori CagA gene alters MUC5AC expression in human gastric cancer cells

Helicobacter pylori, the primary causative agent of stomach cancer, is known to affect gastric mucin expression. However, the underlying molecular mechanisms mediating this H. pylori-dependent effect remain unknown. In the present study, the effect of exogenous expression of the H. pylori virulence factor, CagA, on mucin 5AC oligomeric muscus/gel-forming (MUC5AC) expression was investigated using an in vitro model of the gastric mucosa. AGS cells were either untreated or transfected by a vector control (pCDNA3.1) or heterologous DNA, which induced CagA overexpression (pCDNA3.1-CagA). The expression and functionality of MUC5AC was analyzed using the reverse transcription-quantitative polymerase chain reaction and immunofluorescence assays. The expression of H. pylori-CagA in AGS cells was able to significantly upregulate MUC5AC expression compared to the vector control. In addition, immunofluorescence assays were able to validate increased MUC5AC expression following exogenous expression of H. pylori-CagA. The results of the present study revealed that the H. pylori-derived virulence factor CagA was able to increase the expression of MUC5AC. As this mucin constitutes an important ecological niche for H. pylori, this response may be involved in H. pylori colonization of the stomach.

Intricate and Cell Type-Specific Populations of Endogenous Circular DNA (eccDNA) in Caenorhabditis elegans and Homo sapiens

Investigations aimed at defining the 3D configuration of eukaryotic chromosomes have consistently encountered an endogenous population of chromosome-derived circular genomic DNA, referred to as extrachromosomal circular DNA (eccDNA). While the production, distribution, and activities of eccDNAs remain understudied, eccDNA formation from specific regions of the linear genome has profound consequences on the regulatory and coding capabilities for these regions. Here, we define eccDNA distributions in Caenorhabditis elegans and in three human cell types, utilizing a set of DNA topology-dependent approaches for enrichment and characterization. The use of parallel biophysical, enzymatic, and informatic approaches provides a comprehensive profiling of eccDNA robust to isolation and analysis methodology. Results in human and nematode systems provide quantitative analysis of the eccDNA loci at both unique and repetitive regions. Our studies converge on and support a consistent picture, in which endogenous genomic DNA circles are present in normal physiological states, and in which the circles come from both coding and noncoding genomic regions. Prominent among the coding regions generating DNA circles are several genes known to produce a diversity of protein isoforms, with mucin proteins and titin as specific examples.

Is there a dose-dependent effect of genetic susceptibility loci for gastric cancer on prognosis of the patients?

Literature suggests that genetic variants associated with increased susceptibility to gastric cancer (GCa) are mostly located in genes involved in carcinogenesis and possibly tumor progression. Therefore, we hypothesize that high genetic susceptibility is also associated with prognosis of the patients. To test this hypothesis, we selected a total of 42 common genetic variants that were reportedly associated with GCa risk with a high level of evidence obtained from either genome-wide association studies (GWASs) or meta-analyses and performed survival analysis of patients used in a case-control analysis. We first used 1115 GCa cases and 1172 cancer-free controls of ethnic Han Chinese to construct a weighted genetic risk score (GRS). Then, we included 633 GCa cases with available clinical information, fit GRS in a fractional polynomial Cox proportional hazards regression model to investigate whether there is a dose-dependent effect of GRS on risk of death in survival analysis. Dynamic predictive value of genetic risk for prognosis was also calculated. The results showed that the increase of GRS had no effect on risk of death in these GCa patients. Compared with GCa patients with the medium GRS, there was no significant difference in survival in patients with either a low (P = 0.349) or a high (P = 0.847) GRS. The results unchanged when data were stratified by tumor stage and Lauren's classification. Time-dependent predictive value for prognosis in considering both clinical factors and GRS was comparable with that in considering clinical factors alone, for either all patients (P = 0.986) or stage- and Laruen type-based subgroups (P > 0.05 for all). In conclusion, higher polygenic susceptibility loci for GCa may not indicate worse prognosis of Chinese patients. Additional variants of relevant genes modulating GCa patients' survival need to be further identified.

Adhesion of Lactobacilli and their anti-infectivity potential

The probiotic potential of lactic acid bacteria primarily point toward colonizing ability of Lactobacilli as the most important attribute for endowing all the known beneficial effects in a host. Lactobacillus species exert health-promoting function in the gastrointestinal tract through various mechanisms such as pathogen exclusion, maintenance of microbial balance, immunomodulation, and other crucial functions. It has been seen that many surface layer proteins are involved in host adhesion, and play significant role in the modification of some signaling pathways within the host cells. Interaction between different bacterial cell surface proteins and host receptor has been imperative for a better understanding of the mechanism through which Lactobacilli exert their health-promoting functions.

MUC1 rs4072037 polymorphism is associated with decreased risk of gastric cancer: a meta-analysis

BACKGROUND

Several studies have recently investigated the association between mucin 1 (MUC1) rs4072037 polymorphism and gastric cancer (GC) risk, but with conflicting results. The aim of this meta-analysis was to evaluate the association between MUC1 rs4072037 polymorphism and GC risk.

METHODS

A comprehensive database search of PubMed, Elsevier, Embase and China National Knowledge Infrastructure (CNKI) databases was performed to identify relevant studies. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the strength of any association.

RESULTS

A total of 12 papers containing 18 studies were included in this meta-analysis, involving 12,373 cases and 15,008 controls. Our data suggested that rs4072037 polymorphism was associated with a decreased risk of GC. Stratification analyses of ethnicity indicated that rs4072037 decreased the risk of GC among white populations, but no significant relationship was observed among Asian populations. No significant associations were observed in subgroups of Lauren classification (intestinal or diffuse) and anatomical classification (cardia or non-cardia).

CONCLUSIONS

In conclusion, this meta-analysis suggested that rs4245739 polymorphism in the MUC1 gene may play a pivotal role in the pathogenesis of GC, especially for white populations.

Genetic variants in gastric cancer: Risks and clinical implications

Cancer is a multifactorial disease that involves many molecular alterations. Gastric cancer (GC) is the third leading cause of cancer death worldwide. GC is a highly heterogeneous disease with different molecular and genetics features. Therefore, this review focuses on an overview of the genetic aspects of gastric cancer by highlighting the important impact and role of deletions and/or duplications of chromosomal segments, genomic variants, H. pylori infection and interleukin variants, as found in gene expression and newly proposed molecular classification studies. The challenge is to better understand the mechanisms and different pathways that lead to the development and progression of GC.

MUC1 in lung adenocarcinoma: cross-sectional genetic and serological study

Background

Mucin 1 (MUC1) contributes to the growth and metastasis of various cancers, including lung cancer, and MUC1 gene length polymorphisms are associated with susceptibility to lung cancer and its prognosis. In contrast, the association between rs4072037, a single nucleotide polymorphism in MUC1, and lung cancer has not been well studied.

Methods

In the present study, we determined the rs4072037 genotype and measured serum KL-6 levels to evaluate the association between lung adenocarcinoma (ADC) and rs4072037 or serum KL-6 levels. DNA samples were available for 172 patients and these were included in the genomic analyses. In addition, 304 patients were included in the serum analyses. Furthermore, 276 healthy volunteers were included in both genomic and serum analyses.

Results

The rs4072037 genotype was not associated with susceptibility to lung ADC or its prognosis. Interestingly, serum KL-6 levels significantly differed according to rs4072037 genotype in those with T1 or T2 (P < 0.001), N0 or N1 (P = 0.002) and M0 (P < 0.001), but not in those with T3 or T4 (P = 0.882), N2 or N3 (P = 0.616) and M1a or M1b (P = 0.501). Serum KL-6 levels were significantly associated with the presence of lung ADC, as well as with its progression and prognosis, indicating the crucial involvement of KL-6/MUC1 in the development of lung cancer and its progression.

Conclusion

Based on these findings, we conclude that rs4072037 does not have a significant impact on the pathogenesis or prognosis of lung ADC, whereas serum KL-6 levels, which might reflecting the molecular length of MUC1, are significantly associated with lung ADC.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-017-3272-y) contains supplementary material, which is available to authorized users.

Identification of new susceptibility loci for gastric non-cardia adenocarcinoma: pooled results from two Chinese genome-wide association studies

OBJECTIVE

Although several genome-wide association studies (GWAS) of non-cardia gastric cancer have been published, more novel association signals could be exploited by combining individual studies together, which will further elucidate the genetic susceptibility of non-cardia gastric cancer.

DESIGN

We conducted a meta-analysis of two published Chinese GWAS studies (2031 non-cardia gastric cancer cases and 4970 cancer-free controls) and followed by genotyping of additional 3564 cases and 4637 controls in two stages.

RESULTS

The overall meta-analysis revealed two new association signals. The first was a novel locus at 5q14.3 and marked by rs7712641 (per-allele OR=0.84, 95% CI 0.80 to 0.88; p=1.21×10^-11). This single-nucleotide polymorphism (SNP) marker maps to the intron of the long non-coding RNA, lnc-POLR3G-4 (XLOC_004464), which we observed has lower expression in non-cardia gastric tumour compared with matched normal tissue (P_{wilcoxon signed-rank}=7.20×10^-4). We also identified a new signal at the 1q22 locus, rs80142782 (per-allele OR=0.62; 95% CI 0.56 to 0.69; p=1.71×10^-19), which was independent of the previously reported SNP at the same locus, rs4072037 (per-allele OR=0.74; 95% CI 0.69 to 0.79; p=6.28×10^-17). Analysis of the new SNP conditioned on the known SNP showed that the new SNP remained genome-wide significant (P_conditional=3.47×10^-8). Interestingly, rs80142782 has a minor allele frequency of 0.05 in East Asians but is monomorphic in both European and African populations.

CONCLUSION

These findings add new evidence for inherited genetic susceptibility to non-cardia gastric cancer and provide further clues to its aetiology in the Han Chinese population.

MUC1 Immunohistochemical Expression as a Prognostic Factor in Gastric Cancer: Meta-Analysis

MUC1, a member of the mucin family, is expressed in tumors of various human organs and may function as an antiadhesion molecule that inhibits cell-to-cell adhesion, inducing tumor metastasis, and served as a potential biomarker of tumor progression in early gastric cancer. However, its prognostic significance in gastric cancer is still in dispute. We performed a meta-analysis to evaluate the relationship between MUC1 expression and prognosis of gastric cancer. A total of ten eligible studies with 834 cases and 548 controls were included. MUC1 positive cases were highly positive in intestinal-type carcinomas (OR = 1.76, 95% CI: 1.27–2.44, P = 0.0008 fixed-effect), higher rate of vascular invasion (OR = 1.64, 95% CI: 1.13–2.39, P = 0.009 fixed-effect), and lymph node metastasis (OR = 2.10, 95% CI: 1.20–3.67, P = 0.01 random-effect), as well as lower 5-year survival rate (HR = 0.27, 95% CI: 0.11–0.66, P = 0.004 random-effect). However, the presence of MUC1 was not associated with gender, tumor size, histologic differentiation, and clinical stage. In summary, MUC1 is a prognostic factor in gastric cancer, which acts as a marker of poor outcome in patients with gastric cancer. Further clinical studies are needed to confirm the role of MUC1 in clinical practice.

Genetic variant rs4072037 of MUC1 and gastric cancer risk in an Eastern Chinese population

Published data on the association between the MUC1 rs4072037A > G polymorphism and gastric cancer (GCa) risk were inconclusive. To derive a more precise estimation of the association, we conducted a large GCa study of 1,124 cases and 1,192 controls to confirm this association in an Eastern Chinese population. Our results showed that the G allele was strongly associated with a decreased GCa risk in the study population [GG vs. AA, odds ratio (OR) = 0.47, 95% confidence interval (CI) = 0.31-0.73; AG/GG vs. AA, OR = 0.82, 95% CI = 0.68-0.99; GG vs. AA/AG, OR = 0.48, 95% CI = 0.32-0.74]. These associations remained significant in subgroups of age, tumor site, drinking and smoking status. Moreover, this association was supported by an additional meta-analysis of published studies. In summary, these results suggest that the MUC1 rs4072037G allele may be a low-penetrating protection factor for GCa risk in Chinese populations.

Polymorphisms in mucin genes in the development of gastric cancer

Gastric cancer (GC) is the third leading cause of cancer-related death worldwide. In areas of high prevalence, such as Japan, South Korea and China, most cases of GC are related to Helicobacter pylori (H. pylori), which involves well-characterized sequential stages, including infection, atrophic gastritis, intestinal metaplasia, dysplasia, and GC. Mucins are the most abundant high-molecular-weight glycoproteins in mucus, which is the first line of defense and plays a major role in blocking pathogenic factors. Normal gastric mucosa shows expression of MUC1, MUC5AC and MUC6 that is specific to cell type. However, the specific pattern of MUC1, MUC5AC and MUC6 expression is changed in gastric carcinogenesis, accompanied by de novo expression of secreted MUC2. Recent studies have provided evidence that variations in these mucin genes affect many steps of GC development, such as H. pylori infection, and gastric precancerous lesions. In this review, we focus on studies of the association between polymorphisms in mucin genes and development of GC. This information should be helpful for the early detection, surveillance, and treatment of GC.

Common genetic variations in the MUC5AC gene are not related to helicobacter pylori serologic status

Several lines of evidence suggest that MUC5AC genetic polymorphisms might confer susceptibility to H. pylori infection and therefore gastric cancer risk. We here assessed the association of common polymorphisms in the MUC5AC gene with H. pylori seroprevalence using an LD-based tagSNP approach in a north-western Chinese Han population. A total of 12 tagSNPs were successfully genotyped among 281 unrelated ethnic Han Chinese who had no cancer history, and no identifiable gastric disease or genetic disease. No significant association between any alleles, genotypes or haplotypes and H. pylori seroprevalence was observed. Our results suggest that common genetic variations in MUC5AC gene might not make a major contribution to the risk of H. pylori infection.

Exploring the role and diversity of mucins in health and disease with special insight into non-communicable diseases

Mucins are major glycoprotein components of the mucus that coats the surfaces of cells lining the respiratory, digestive, gastrointestinal and urogenital tracts. They function to protect epithelial cells from infection, dehydration and physical or chemical injury, as well as to aid the passage of materials through a tract i.e., lubrication. They are also implicated in the pathogenesis of benign and malignant diseases of secretory epithelial cells. In Human there are two types of mucins, membrane-bound and secreted that are originated from mucous producing goblet cells localized in the epithelial cell layer or in mucous producing glands and encoded by MUC gene. Mucins belong to a heterogeneous family of high molecular weight proteins composed of a long peptidic chain with a large number of tandem repeats that form the so-called mucin domain. The molecular weight is generally high, ranging between 0.2 and 10 million Dalton and all mucins contain one or more domains which are highly glycosylated. The size and number of repeats vary between mucins and the genetic polymorphism represents number of repeats (VNTR polymorphisms), which means the size of individual mucins can differ substantially between individuals which can be used as markers. In human it is only MUC1 and MUC7 that have mucin domains with less than 40% serine and threonine which in turn could reduce number of PTS domains. Mucins can be considered as powerful two-edged sword, as its normal function protects from unwanted substances and organisms at an arm's length while, malfunction of mucus may be an important factor in human diseases. In this review we have unearthed the current status of different mucin proteins in understanding its role and function in various non-communicable diseases in human with special reference to its organ specific locations. The findings described in this review may be of direct relevance to the major research area in biomedicine with reference to mucin and mucin associated diseases.

Loss-of-function variants in ATM confer risk of gastric cancer

Gastric cancer is a serious health problem worldwide, with particularly high prevalence in eastern Asia. Genome-wide association studies (GWAS) in Asian populations have identified several loci that associate with gastric cancer risk. Here we report a GWAS of gastric cancer in a European population, using information on 2,500 population-based gastric cancer cases and 205,652 controls. We found a new gastric cancer association with loss-of-function mutations in ATM (gene test, P = 8.0 × 10(-12); odds ratio (OR) = 4.74). The combination of the loss-of-function variants p.Gln852*, p.Ser644* and p.Tyr103* (combined minor allele frequency (MAF) = 0.3%) also associates with pancreatic and prostate cancers (OR = 3.81 and 2.18, respectively) and gives an indication of risk of breast and colorectal cancers (OR = 1.82 and 1.97, respectively). Cancers in those carrying loss-of-function ATM mutations are diagnosed at a significantly earlier age than in non-carriers. Our results confirm an association between gastric cancer in Europeans and three loci previously reported in Asians, MUC1, PRKAA1 and PSCA, refine the association signal at PRKAA1 and support a pathogenic role for the tandem repeat identified in MUC1.

Association analysis of common genetic variations in MUC5AC gene with the risk of non-cardia gastric cancer in a Chinese population

Several lines of evidence suggest that genetic variation in MUC5AC gene might contribute to the risk of gastric cancer. We conducted a case-control study to evaluate the relationship between common genetic variations in MUC5AC gene and non-cardia gastric cancer using an LD-based tagSNP approach in Baotou, north-western China. We genotyped 12 tagSNPs by TaqMan method among 288 cases with non-cardia gastric cancer and 281 normal controls. Unconditional logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for non-cardia gastric cancer risk in association with alleles, genotypes and haplotypes. We observed that the frequencies of rs3793964 C allele and rs11040869 A allele were significantly lower in cases than in controls. Meanwhile, minor allele homozygotes of rs3793964 and rs11040869 were significantly associated with a decreased risk of non-cardia gastric cancer when compared with their major allele homozygotes. Furthermore, a statistically significantly protective effect of rs885454 genotypes on non-cardia gastric cancer was also observed (for CT vs. CC: OR=0.581, 95%CI=0.408-0.829; for CT/TT vs. CC: OR=0.623, 95%CI=0.451-0.884). Our results indicated that some common genetic variations in the MUC5AC gene might have effects on the risk of non-cardia gastric cancer in our studied population.

Lack of association of common polymorphisms in MUC1 gene with H. pylori infection and non-cardia gastric cancer risk in a Chinese population

Several lines of evidence support the notion that MUC1 is often aberrantly expressed in gastric cancer, and it is a ligand for Helicobacter pylori. Genetic variation in MUC1 gene may confer susceptibility to H. pylori infection and gastric cancer. We assessed the association of common polymorphisms in MUC1 gene with H. pylori infection and non-cardia gastric cancer using an LD-based tag SNP approach in north-western Chinese Han population. A total of four SNPs were successfully genotyped among 288 patients with non-cardia gastric cancer and 281 age- and sex-matched controls. None of the tested SNPs was associated with H. pylori infection. SNP rs9426886 was associated with a decreased risk of non-cardia gastric cancer, but lost significance after adjustment for multiple testing. Overall, our data indicated that common genetic variations in MUC1 gene might not make a major contribution to the risk of H. pylori infection and non-cardia gastric cancer in our studied population.

Genetics of gastric cancer

Gastric cancer remains highly prevalent and accounts for a notable proportion of global cancer mortality. This cancer is also associated with poor survival rates. Understanding the genetic basis of gastric cancer will offer insights into its pathogenesis, help identify new biomarkers and novel treatment targets, aid prognostication and could be central to developing individualized treatment strategies in the future. An inherited component contributes to <3% of gastric cancers; the majority of genetic changes associated with gastric cancer are acquired. Over the past few decades, advances in technology and high-throughput analysis have improved understanding of the molecular aspects of the pathogenesis of gastric cancer. These aspects are multifaceted and heterogeneous and represent a wide spectrum of several key genetic influences, such as chromosomal instability, microsatellite instability, changes in microRNA profile, somatic gene mutations or functional single nucleotide polymorphisms. These genetic aspects of the pathogenesis of gastric cancer will be addressed in this Review.

MUC1 gene polymorphism rs4072037 and susceptibility to gastric cancer: a meta-analysis

The association between MUC1 polymorphism rs4072037 and the risk of gastric cancer has been described in several studies. However, these studies yielded inconsistent results, especially in different pathological type of gastric cancer. Therefore, we performed this meta-analysis to evaluate the relationship between MUC1 gene polymorphism and gastric cancer susceptibility. A comprehensive database search was performed to identify eligible studies. Odds ratios with 95% confidence intervals were calculated to assess the strength of the association between MUC1 rs4072037 and risk of gastric cancer. Subgroup analyses, publication bias, and sensitivity analyses were also conducted. PubMed, EMBASE, Web of Science and CNKI databases were systematically searched to identify relevant studies. A total of 9 studies (12 datasets) were included in the meta-analysis including 10,410 cases and 11,437 controls. Overall, the G allele at rs4072037 of MUC1 gene was associated with a significant decreased gastric cancer risk (OR=0.70, 95% CI: 0.64-0.76). The association was significant in both anatomic location and pathological subtype subgroup analyses. However, the association was detected in Asian rather than Caucasian. Our findings demonstrate that the presence of the G allele at rs4072037 of the MUC1 gene may contribute to protection against gastric cancer in Asian. Further large studies of multiethnic groups are needed to validate these findings.

Genetic and intermediate phenotypic susceptibility markers of gastric cancer in Hispanic Americans: a case-control study

BACKGROUND

Hispanics are the largest nonwhite ethnic group in the US population, and they have higher incidence and mortality rates for gastric cancer (GC) than whites and Asians. Studies have identified several genetic susceptibility loci and intermediate phenotypic biomarkers for GC in whites and Asians. No studies have evaluated genetic susceptibility and intermediate phenotypic biomarkers in Hispanics.

METHODS

In a case-control study of 132 Hispanic patients with GC (cases) and a control group of 125 Hispanics (controls), the authors evaluated the association of 5 single nucleotide polymorphisms (SNPs) that predispose whites and/or Asians to GC and of 2 intermediate phenotypic markers in peripheral blood leukocytes, ie, telomere length and mitochondrial DNA (mtDNA) copy number, with the GC risk.

RESULTS

The variant C allele of the reference SNP rs2294008 in the PSCA gene was associated with a significantly reduced risk of GC (per allele-adjusted odds ratio [aOR], 0.51; 95% confidence interval [CI], 0.33-0.77; P = .002). Leukocyte mtDNA copy numbers were significantly lower in GC cases (mean ± standard deviation, 0.91 ± 0.28) than in controls (1.29 ± 0.42; P < .001). When individuals were dichotomized into high and low mtDNA copy number groups based on the median mtDNA copy number value in the controls, those who had a low mtDNA copy number had a significantly increased risk of GC (aOR, 11.00; 95% CI, 4.79-25.23; P < .001) compared with those who had a high mtDNA copy number. Telomere length was not associated significantly with the risk of GC (aOR, 1.21; 95% CI, 0.65-2.27; P = .551).

CONCLUSIONS

Hispanics share certain genetic susceptibility loci and intermediate phenotypic GC biomarkers with whites and Asians and may also have distinct genetic susceptibility factors.

Mucin 1 gene (MUC1) and gastric-cancer susceptibility

Gastric cancer (GC) is one of the major malignant diseases worldwide, especially in Asia. It is classified into intestinal and diffuse types. While the intestinal-type GC (IGC) is almost certainly caused by Helicobacter pylori (HP) infection, its role in the diffuse-type GC (DGC) appears limited. Recently, genome-wide association studies (GWAS) on Japanese and Chinese populations identified chromosome 1q22 as a GC susceptibility locus which harbors mucin 1 gene (MUC1) encoding a cell membrane-bound mucin protein. MUC1 has been known as an oncogene with an anti-apoptotic function in cancer cells; however, in normal gastric mucosa, it is anticipated that the mucin 1 protein has a role in protecting gastric epithelial cells from a variety of external insults which cause inflammation and carcinogenesis. HP infection is the most definite insult leading to GC, and a protective function of mucin 1 protein has been suggested by studies on Muc1 knocked-out mice.

The effect of MUC1 rs4072037 functional polymorphism on cancer susceptibility: evidence from published studies

Genome-wide association studies have identified a susceptibility variation MUC1 rs4072037 for gastric cancer in Chinese population. Subsequent case-control studies have reported this association in other populations. However, the results remain controversial and ambiguous. The aim of this study is to provide a precise quantification for the association between MUC1 rs4072037 variation and the risk of cancer. We performed pooled analysis of 10 case-control designed studies including 4,220 cases and 6,384 controls. Odds ratios (OR) and 95% confidence interval (95%CI) were calculated to assess strength of association in overall studies and in subgroup analysis stratified by ethnicity and cancer types. All statistical analyses were performed by Manager 5.0 and Stata 12.0 software. Overall, the MUC1 rs4072037 polymorphism was associated with risk of cancer in all genetic models (G vs A: OR = 0.71, 95%CI: 0.63-0.80, p<0.01; GA vs AA: OR = 0.61, 95%CI:0.55-0.67, p<0.01; GG vs AA: OR = 0.58, 95%CI: 0.47-0.71, p<0.01; AG+AA vs GG: OR = 0.60, 95%CI: 0.55-0.60, p<0.01; GG vs AG+AA: OR = 0.70, 95%CI: 0.58-0.85, p<0.01). Further, subgroup analysis based on ethnicity suggested MUC1 rs4072037 polymorphism had a subtly reduced cancer risk among Asian population, and stratified analysis by cancer types showed significantly decreased risk of gastric cancer in all genetic models. In conclusion, MUC1 rs4072037 polymorphism may be used as potential biomarker for cancer susceptibility particularly for gastric cancer and for Asian population.

The changes in MUC5AC expression in gastric cancer before and after Helicobacter pylori eradication

PURPOSE

To investigate MUC5AC expression in gastric cancer before and after Hp eradication.

METHODS

The MUC5AC protein and mRNA were detected in gastric cancer tissue by western blot and real time PCR protocols before and after Hp eradication (Hp positive group). Gastric cancer tissue without Hp infection served as the control group (Hp negative group).

RESULTS

The MUC5AC protein and mRNA expression was more significantly increased in gastric cancer after Hp eradication as compared to that before Hp eradication, but it was significantly lower than of the control group. The relative amount of MUC5AC in the well-differentiated cancer was higher than that of the moderately or poorly-differentiated cancer, in either Hp positive or control groups. The relative amount of MUC5AC in cancer tissues with more than five metastatic lymph nodes was significantly lower than that of the cancer tissues with five or less metastatic lymph nodes, and was significantly lower in the Hp positive group as compared to that of the control group.

CONCLUSIONS

The reduction of the MUC5AC might be related to gastric carcinogenesis caused by Hp and the progression of gastric cancer.

Gastric cancer susceptibility genes

Genetic susceptibility results from genetic factors or some genetic defects, and endows the offspring with some physiological and metabolic features prone to certain diseases. At present, gastric cancer susceptibility genes have become a hot research topic in China, and the identification and characterization of gastric cancer susceptibility genes can help develop methods for exploring gastric cancer etiology and provide a scientific basis for the prevention and control of this malignancy. In this paper, we will review the current progress in research of gastric cancer susceptibility genes.

Host genetic factors respond to pathogenic step-specific virulence factors of Helicobacter pylori in gastric carcinogenesis

The interindividual differences in risk of Helicobacter pylori (H. pylori)-associated gastric cancer involve significant heterogeneities of both host genetics and H. pylori strains. Several recent studies proposed a distinct sequence for H. pylori exerting its virulence in the host stomach: (i) adhering to and colonizing the surface of gastric epithelial cells, (ii) evading and attenuating the host defense, and (iii) invading and damaging the gastric mucosa. This review focuses on several key issues that still need to be clarified, such as which virulence factors of H. pylori are involved in the three pathogenic steps, which host genes respond to the step-specific virulence factors, and whether and/or how the corresponding host genetic variations influence the risk of gastric carcinogenesis. Urease, BabA and SabA in the adhesion-step, PGN and LPS in the immune evasion-step, and CagA, VacA and Tipα in the mucosal damage-step were documented to play an important role in step-specific pathogenicity of H. pylori infection. There is evidence further supporting a role of potentially functional polymorphisms of host genes directly responding to these pathogenic step-specific virulence factors in the susceptibility of gastric carcinogenesis, especially for urease-interacting HLA class II genes, BabA-interacting MUC1, PGN-interacting NOD1, LPS-interacting TLR4, and CagA-interacting PTPN11 and CDH1. With the continuous improvement of understanding the genetic profile of H. pylori-associated gastric carcinogenesis, a person at increased risk for gastric cancer may benefit from several aspects of efforts: (i) prevent H. pylori infection with a vaccine targeting certain step-specific virulence factor; (ii) eradicate H. pylori infection by blocking step-specific psychopathological characteristics of virulence factors; and (iii) adjust host physiological function to resist the carcinogenic role of step-specific virulence factors or interrupt the cellular signal transduction of the interplay between H. pylori and host in each pathogenic step, especially for the subjects with precancerous lesions in the stomach.

Common genetic variants at 1q22 and 10q23 and gastric cancer susceptibility in a Korean population

Genetic variants at 1q22 and 10q23 were identified as genetic markers of both gastric cancer and esophageal squamous cell carcinoma susceptibility by two genome-wide association studies. The aim of this study was to determine whether rs4072037A > G in MUC1 at 1q22 and rs2274223A > G in PLCE1 at 10q23 are associated with a risk of gastric cancer in a Korean population. We conducted a large-scale case-control study of 3,245 patients with gastric cancer and 1,700 controls. The allele frequencies of rs4072037G and rs2274223G were 11.2 and 25.5% among patients with gastric cancer, compared with 12.8 and 26.4%, respectively, among controls. We found that the rs4072037 AG genotype was significantly associated with a reduced risk of gastric cancer [odds ratios (OR) = 0.78; 95% confidence interval (CI) = 0.67-0.91 for AG vs AA]. Compared with the rs2274223 AA genotype, we found a significant association between the rs2274223 AG genotype and a weakly reduced risk of gastric cancer (OR = 0.87; 95% CI = 0.76-0.99 for AG vs AA). Our data suggest that genetic variants at 1q22 and 10q23 play a role in gastric carcinogenesis.

Functional polymorphism rs4072037 in MUC1 gene contributes to the susceptibility to gastric cancer: evidence from pooled 6,580 cases and 10,324 controls

Genome-wide association studies have reported a promising association of rs4072037 with gastric cancer (GC). This variant was associated with altered physiological function of MUC1 possibly by modulating promoter activity and alternative splicing of MUC1. However, the association results were inconclusive and estimate of the effect of this variant was not well evaluated. A meta-analysis by systematically reviewing relevant reports may facilitate to address these concerns. Association studies involving MUC1 rs4072037 polymorphism and GC risk were identified up to June 30, 2012. Odds ratio (OR) and 95 % confidence interval (CI) in additive model were estimated or extracted from each study. The pooled effect size was quantitatively synthesized using meta-analysis. Heterogeneity between studies was measured by the Q test and I (2) statistic, and publication bias was evaluated by a funnel plot and the Egger's test. A total of 10 independent case-control studies including 6,580 GC cases and 10,324 controls were included in this meta-analysis. Eight of the ten studies were Asian ethnicity and two European. The G allele of MUC1 rs4072037 was significantly associated with a decreased risk of GC (OR = 0.72, 95 % CI 0.68-0.77; P = 7.82 × 10(-25)), as compared with A allele. Stratification for different ethnicity, tumor localization or type showed similar results. These findings represent important evidence for association of MUC1 rs4072037 variant with GC risk, and also provide a relatively reliable estimate of effect size. MUC1 is a strong candidate as a susceptibility gene of GC.

Mucins in Gastric Cancer - An Update

Mucins are high-molecular-weight glycoproteins expressed throughout the gastrointestinal tract, with a key role in mucosal protection and function. In gastric cancer expression of MUC5AC and MUC1 is reduced and denovo expression of MUC2 occurs. With progressive loss of tumor differentiation and increased tumor stage, expression of MUC5AC and MUC1 is further reduced, and MUC2 decreases. Isolated MUC2 expression (the intestinal phenotype) correlates with metastatic spread and poor survival. There is emerging evidence that MUC1 acts as an oncoprotein when overexpressed. The cytoplasmic tail of MUC1 interacts with the H. pylori virulence factor cagA and is a major effector of the wnt-β catenin intracellular signalling cascade. Polymorphism in the MUC1 gene has been identified in gastric cancer patients and may have a prospective role in the stratification of high-risk subjects. The MUC1 gene also mediates resistance to the recombinant HER2/neu antibody trastuzumab. Future research efforts will examine targeting MUC1 for therapeutic purposes.

An overview of current research of gastric hyperplastic polyps

Gastric hyperplastic polyp (GHP) is one of the most common polypoid lesions of the stomach and has the potential of malignant transformation. This article gives a review of recent progress in research of GHP in terms of clinical and pathological factors, pathogenesis, relation with atypical hyperplasia and canceration, molecular biology and mucin expression.

Association of genetic polymorphisms at 1q22 but not 10q23 with gastric cancer in a southern Chinese population

OBJECTIVE

Data from a recent genome-wide association studiesy of gastric cancer (GC) and oesophageal squamous cell carcinoma in Chinese living in the Taihang Mountains of north-central China suggest that 1q22 and 10q23 are susceptibility-associated regions for GC. However, this has not been confirmed in southern Chinese populations. The aim of this study was to investigate whether these polymorphisms at 1q22 and 10q23 are associated with the risk of GC in a southern Chinese population.

METHODS

We selected seven top significant associated single nucleotide polymorphisms (SNPs) at 1q22 and 10q23 and conducted a population-based case- control study in a southern Chinese population. Genotypes were determined using MassARRAYTM system (Sequenome, San Diego, CA).

RESULTS

Two SNPs at 1q22, rs4072037 and rs4460629, were significantly associated with a reduced risk of GC, best fitting the dominant genetic model. Logistic regression models adjusted for age and sex showed that rs4072037 AG and GG (OR=0.64, P=0.017, compared with AA) and rs4460629 CT and TT (OR=0.54, P=0.0016, compared with TT) significantly reduced the risk of GC. However, no significant results for the five SNPs at 10q23 were obtained in this study.

CONCLUSION

These outcomes indicate that 1q22 is associated with GC susceptibility in this southern Chinese population, while an association for the locus at 10q23 was not confirmed.

Case-control study of single nucleotide polymorphisms of PSCA and MUC1 genes with gastric cancer in a Chinese

AIMS

A case-control study of 300 gastric cancer patients and 300 controls was conducted to investigate whether the polymorphisms rs2294008 in PSCA and rs2070803 in MUC1 might be associated with risk of gastric cancer in a Chinese population.

METHODS

Single nucleotide polymorphisms (SNPs) were genotyped using the Sequenom MassARRAY platform.

RESULTS

The data showed that the rs2294008 TT genotype increased gastric cancer risk to an adjusted odds ratio (OR) of 2.26 (95%CI 1.25-4.07), TC to 1.72 (95%CI 1.23-2.42) and TC/TT to 1.81 (95% CI 1.31-2.50), while the rs2070803 GA genotype was associated with a decrease in risk to an adjusted OR of 0.42 (95% CI 0.28-0.62) and rs2070803 GA / AA to 0.46 (95% CI 0.32-0.67). Further stratification analysis revealed that rs2294008 in PSCA consistently increased risk of both intestinal and diffuse-type gastric cancers. The effect of rs2070803 in MUC1 was noteworthily also consistent with both subtypes.

CONCLUSIONS

Our study suggested rs2294008 in the PSCA gene to be associated with increased risk of gastric cancer and rs2070803 in MUC1 to play a protective role in a Chinese population.

Genetic factors related to gastric cancer susceptibility identified using a genome-wide association study

Gastric cancer (GC) is one of the major malignant diseases worldwide, especially in Asia, where Japan and Korea have the highest incidence in the world. Gastric cancer is classified into intestinal and diffuse types. While the former is almost absolutely caused by Helicobacter pylori infection as the initial insult, the latter seems to include cases in which the role of infection is limited, if any, and a contribution of genetic factors is anticipated. Previously, we performed a genome-wide association study (GWAS) on diffuse-type GC by using single nucleotide polymorphisms (SNP) catalogued for Japanese population (JSNP), and identified a prostate stem cell antigen (PSCA) gene encoding a glycosylphosphatidylinositol-anchored cell surface antigen as a GC susceptibility gene. From the second candidate locus identified using the GWAS, 1q22, we found the Mucin 1 (MUC1) gene encoding a cell membrane-bound mucin protein as another gene related to diffuse-type GC. A two-allele analysis based on risk genotypes of the two genes revealed approximately 95% of Japanese population have at least one of the two risk genotypes, and approximately 56% of the population have both risk genotypes. The two-SNP genotype might offer ample room to further stratify a high GC risk subpopulation in Japan and Asia by adding another genetic and/or non-genetic factor. Recently, a GWAS on the Chinese population disclosed an additional three GC susceptibility loci: 3q13.31, 5p13.1 and 10q23.