Clinicopathological and prognostic significance of mucin phenotype in gastric cancer

Prognostic and clinicopathological significance of mucin family members expression in gastric cancer: a meta-analysis

Background

Mucin family members have been reported to be widely expressed in gastric carcinoma with diverse functions. Several important mucins exert the function of tumorigenesis or progression in gastric cancer (GC). Here, we conduct this meta-analysis to evaluate the association between mucin expression and clinicopathological features in GC.

Methods

Literature searches were performed in PubMed, Embase, The Cochrane Library, and ISI Web of Science, and, finally, 28 studies met our criteria. Odds ratios or hazard ratios with 95% confidence intervals were calculated to evaluate the effect quantity. We analyzed the expression of MUC1, MUC2, MUC5AC, and MUC6 and their clinicopathological characteristics separately at the same time.

Results

Twenty-eight studies that contain 4,603 patients were included in our meta-analysis. MUC1 was associated with gender, Lauren classification, depth of tumor invasion, TNM, vascular invasion, lymph metastasis, and lymphatic invasion, WHO grade, as well as the 5-year survival rate. MUC2 was significantly correlated with lymphatic invasion and WHO grade. MUC5AC was highly positive in gender, depth of tumor invasion, WHO grade, TNM, lymph metastasis, and lymphatic invasion. Moreover, cases with decreased MUC5AC expression were correlated with less 5-year survival. MUC6 was only related with lymphatic invasion.

Conclusion

Our meta-analysis showed that MUC1 and MUC5AC had prognostic value in GC detected by immunohistochemistry. MUC1 and MUC5AC were also associated with some other significant clinicopathological parameters. Moreover, MUC2 and MUC6 also exert their influence in lymphatic invasion. However, further enlarged study awaits to verify our conclusion to deeply explore the role of mucin family members in GC.

Mucin phenotype and microvessels in early gastic cancer: Magnifying endoscopy with narrow band imaging

Backgrounds

In order to detect early gastric cancer (EGC), this research sought to assess the diagnostic utility of magnifying endoscopy (ME) as well as the significance of mucin phenotype and microvessel features.

Methods

402 individuals with an EGC diagnosis underwent endoscopic submucosal dissection (ESD) at the Department of ME between 2012 and 2020. After adjusting for image distortion, high-magnification endoscopic pictures were taken and examined to find microvessels in the area of interest. The microvessel density was measured as counts per square millimeter (counts/mm2) after segmentation, and the vascular bed's size was computed as a percentage of the area of interest. To identify certain properties of the microvessels, such as end-points, crossing points, branching sites, and connection points, further processing was done using skeletonized pixels.

Results

According to the research, undifferentiated tumors often lacked the MS pattern and showed an oval and tubular microsurface (MS) pattern, but differentiated EGC tumors usually lacked the MS pattern and presented a corkscrew MV pattern. Submucosal invasion was shown to be more strongly associated with the destructive MS pattern in differentiated tumors as opposed to undifferentiated tumors. While lesions with a corkscrew MV pattern and an antrum or body MS pattern revealed greater MUC5AC expression, lesions with a loop MV pattern indicated higher MUC2 expression. Furthermore, CD10 expression was higher in lesions with a papillary pattern and an antrum or body MS pattern.

Conclusion

These results imply that evaluating mucin phenotype and microvessel features in conjunction with magnifying endoscopy (ME) may be a useful diagnostic strategy for early gastric cancer (EGC) detection. Nevertheless, further investigation is required to confirm these findings and identify the best course of action for EGC diagnosis.

A genome-wide study of gastric intramucosal neoplasia based on somatic copy number alterations, gene mutations, and mRNA expression patterns

We performed comprehensive analyses of somatic copy number alterations (SCNAs) and gene expression profiles of gastric intramucosal neoplasia (IMN) using array-based methods in 97 intestinal-type IMNs, including 39 low-grade dysplasias (LGDs), 37 high-grade dysplasias (HGDs), and 26 intramucosal carcinomas (IMCs) with stromal invasion of the lamina propria to identify the molecular mechanism of IMN. In addition, we examined gene mutations using gene panel analyses. We used cluster analyses for exclusion of arbitrariness to identify SCNA patterns and expression profiles. IMNs were classified into two distinct subgroups (subgroups 1 and 2) based on SCNA patterns. Subgroup 1 showed a genomic stable pattern due to the low frequency of SCNAs, whereas subgroup 2 exhibited a chromosomal instability pattern due to the high frequencies of SCNAs and TP53 mutations. Interestingly, although the frequencies of LGD and HGD were significantly higher in subgroup 1 than in subgroup 2, IMC was commonly found in both types. Although the expression profiles of specific mRNAs could be used to categorise subgroups 1 and 2, no clinicopathological findings correlated with either subgroup. We examined signalling pathways specific to subgroups 1 and 2 to identify the association of each subgroup with signalling pathways based on gene ontology tree visualisation: subgroups 1 and 2 were associated with haem metabolism and chromosomal instability, respectively. These findings reveal a comprehensive genomic landscape that highlights the molecular complexity of IMNs and provide a road map to facilitate our understanding of gastric IMNs.

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.

Association of CDX2 and mucin expression with chemotherapeutic benefits in patients with stage II/III gastric cancer

BACKGROUND

Better predictors of patients with stage II/III gastric cancer (GC) most likely to benefit from adjuvant chemotherapy are urgently needed. This study aimed to assess the ability of CDX2 and mucin markers to predict prognosis and fluorouracil-based adjuvant chemotherapy benefits.

METHODS

CDX2 and mucin protein expressions were examined by immunohistochemistry and compared with survival and adjuvant chemotherapy benefits in a prospective evaluation cohort of 782 stage II/III GC patients. Then, the main findings were validated in an independent validation cohort (n = 386) and an external mRNA sequencing dataset (ACRG cohort, n = 193).

RESULTS

In the evaluation cohort, CDX2, CD10, MUC2, MUC5AC, and MUC6 expressions were observed in 59.7%, 26.7%, 27.6%, 55.1%, and 57.7% of patients, respectively. However, only the expression of CDX2 was found to be associated with adjuvant chemotherapy benefits. Most importantly, CDX2-negative patients had a poorer prognosis when treated with surgery only, while the prognosis of CDX2-negative and CDX2-positive patients was similar when receiving postoperative adjuvant chemotherapy. Further analysis revealed that patients with CDX2 negative tumors benefited from chemotherapy (5-year overall survival rates: 60.0% with chemotherapy vs. 23.2% with surgery-only, p < 0.001), whereas patients with CDX2 positive tumors did not (pinteraction  = 0.004). Consistent results were obtained in the validation and ACRG cohorts.

CONCLUSIONS

Negative expression of CDX2 is an independent risk factor for survival in stage II/III GC, but subsequent adjuvant chemotherapy is able to compensate for this unfavorable effect. Therefore, active chemotherapy is more urgent for patients with negative CDX2 expression than for patients with positive CDX2 expression.

Mucin-microbiome signatures shape the tumor microenvironment in gastric cancer

BACKGROUND AND AIMS

We aimed to identify mucin-microbiome signatures shaping the tumor microenvironment in gastric adenocarcinomas and clinical outcomes.

METHODS

We performed high-throughput profiling of the mucin phenotypes present in 108 gastric adenocarcinomas and 20 functional dyspepsia cases using validated mucin-based RT-qPCRs with subsequent immunohistochemistry validation and correlated the data with clinical outcome parameters. The gastric microbiota was assessed by 16S rRNA gene sequencing, taxonomy, and community composition determined, microbial networks analyzed, and the metagenome inferred in association with mucin phenotypes and expression.

RESULTS

Gastric adenocarcinomas with an intestinal mucin environment or high-level MUC13 expression are associated with poor survival. On the contrary, gastric MUC5AC or MUC6 abundance was associated with a more favorable outcome. The oral taxa Neisseria, Prevotella, and Veillonella had centralities in tumors with intestinal and mixed phenotypes and were associated with MUC13 overexpression, highlighting their role as potential drivers in MUC13 signaling in GC. Furthermore, dense bacterial networks were observed in intestinal and mixed mucin phenotype tumors whereas the lowest community complexity was shown in null mucin phenotype tumors due to higher Helicobacter abundance resulting in a more decreased diversity. Enrichment of oral or intestinal microbes was mucin phenotype dependent. More specifically, intestinal mucin phenotype tumors favored the establishment of pro-inflammatory oral taxa forming strong co-occurrence networks.

CONCLUSIONS

Our results emphasize key roles for mucins in gastric cancer prognosis and shaping microbial networks in the tumor microenvironment. Specifically, the enriched oral taxa associated with aberrant MUC13 expression can be potential biomarkers in predicting disease outcomes. Video Abstract.

Shared features of metaplasia and the development of adenocarcinoma in the stomach and esophagus

Introduction: Plasticity is an inherent property of the normal gastrointestinal tract allowing for appropriate response to injury and healing. However, the aberrancy of adaptable responses is also beginning to be recognized as a driver during cancer development and progression. Gastric and esophageal malignancies remain leading causes of cancer-related death globally as there are limited early disease diagnostic tools and paucity of new effective treatments. Gastric and esophageal adenocarcinomas share intestinal metaplasia as a key precancerous precursor lesion.

Methods: Here, we utilize an upper GI tract patient-derived tissue microarray that encompasses the sequential development of cancer from normal tissues to illustrate the expression of a set of metaplastic markers.

Results: We report that in contrast to gastric intestinal metaplasia, which has traits of both incomplete and complete intestinal metaplasia, Barrett's esophagus (i.e., esophageal intestinal metaplasia) demonstrates hallmarks of incomplete intestinal metaplasia. Specifically, this prevalent incomplete intestinal metaplasia seen in Barrett's esophagus manifests as concurrent development and expression of both gastric and intestinal traits. Additionally, many gastric and esophageal cancers display a loss of or a decrease in these characteristic differentiated cell properties, demonstrating the plasticity of molecular pathways associated with the development of these cancers.

Discussion: Further understanding of the commonalities and differences governing the development of upper GI tract intestinal metaplasias and their progression to cancer will lead to improved diagnostic and therapeutic avenues.

Vascular endothelial growth factor-A is an Immunohistochemical biomarker for the efficacy of bevacizumab-containing chemotherapy for duodenal and jejunal adenocarcinoma

BACKGROUND

The efficacy and safety of bevacizumab-containing chemotherapy for patients with metastatic duodenal and jejunal adenocarcinoma (mDJA) are unclear. The present study aimed to evaluate the efficacy of bevacizumab and to explore immunohistochemical markers that can predict the efficacy of bevacizumab for patients with mDJA.

METHODS

This multicentre study included patients with histologically confirmed small bowel adenocarcinoma who received palliative chemotherapy from 2008 to 2017 at 15 hospitals. Immunostaining was performed for vascular endothelial growth factor-A (VEGF-A), TP53, Ki67, β-catenin, CD10, MUC2, MUC5AC, MUC6, and mismatch repair proteins.

RESULTS

A total of 74 patients were enrolled, including 65 patients with mDJA and 9 with metastatic ileal adenocarcinoma. Patients with mDJA who received platinum-based chemotherapy with bevacizumab as first-line treatment tended to have a longer progression-free survival and overall survival than those treated without bevacizumab (P = 0.075 and 0.077, respectively). Multivariate analysis extracted high VEGF-A expression as a factor prolonging progression-free survival (hazard ratio: 0.52, 95% confidence interval: 0.30-0.91). In mDJA patients with high VEGF-A expression, those who received platinum-based chemotherapy with bevacizumab as a first-line treatment had significantly longer progression-free survival and tended to have longer overall survival than those treated without bevacizumab (P = 0.025 and P = 0.056, respectively), whereas no differences were observed in mDJA patients with low VEGF-A expression.

CONCLUSION

Immunohistochemical expression of VEGF-A is a potentially useful biomarker for predicting the efficacy of bevacizumab-containing chemotherapy for patients with mDJA.

Clinical and phenotypical characteristics of submucosal invasive carcinoma in non-ampullary duodenal cancer

OBJECTIVE

The rare incidence of submucosal invasive non-ampullary duodenal carcinoma has led to scant information in literature; therefore, we compared the clinicopathological features between submucosal invasive carcinoma (SM-Ca), mucosal carcinoma (M-Ca), and advanced carcinoma (Ad-Ca).

MATERIALS

We retrospectively analyzed 165 patients with sporadic non-ampullary duodenal carcinomas (SNADCs) from four institutions between January 2003 and December 2018. The SNADCs were divided to three groups according to histological diagnosis: SM-Ca, M-Ca, and Ad-Ca. The clinicopathological characteristics and mucin phenotypes were compared between groups.

RESULTS

Among the 165 SNADCs, 11 (7%) were classified as SM-Ca, 70 (42%) as M-Ca, and 84 (51%) as Ad-Ca. We found that all SM-Ca (P = 0.013) and most Ad-Ca (P = 0.020) lesions were located on the oral-Vater; however, an almost equal distribution of M-Ca lesions was found between the oral- and anal-Vater. No significant difference was observed between the tumor diameter of M-Ca and SM-Ca; however, 45% (5/11) of SM-Ca were ≤10 mm. A total of 73% (8/11) of SM-Ca were classified as gastric phenotype and no lesions were classified as intestinal phenotype; whereas most M-Ca were classified as intestinal phenotype (67%, 8/12).

CONCLUSIONS

SM-Ca lesions were all located on the oral-Vater and were highly associated with the gastric mucin phenotype, which were different from the features of most M-Ca.

Clinicopathological characteristics of mucin phenotype and its relation to the malignant potential in early differentiated gastric adenocarcinoma

Objectives

Mucin phenotype is a tool to classify gastric cancer, but the relationship between mucin phenotype and its malignancy is still controversial. This study aimed to clarify the relationship between mucin phenotype and the malignant potential of gastric cancer.

Methods

A total of 82 cases of early-stage differentiated adenocarcinoma (submucosal invasion cases) obtained from surgeries were studied by immunohistochemistry. Gastric mucin phenotype and E-cadherin expression were analyzed in the mucosal and submucosal layer. E-cadherin expression was analyzed by using imaging software (ImageJ) for objective data analysis. Furthermore, the mucin phenotypic shift was analyzed from mucosa to submucosa.

Results

We found that: (1) tumors with intestinal mucin phenotype had statistically more venous invasion in the submucosal lesion; (2) tumors with an intestinal phenotype that showed venous invasion in the submucosal lesion had a higher percentage of tumors that showed loss of phenotype; (3) no dominant change in E-cadherin expression was observed from the mucosa to submucosa.

Conclusion

Tumors with loss of phenotype and submucosal intestinal phenotype showed predominantly more venous invasion, so examining the identification of phenotypes and phenotype shifts can be expected to be a factor that influences treatment strategies after endoscopic treatment or after surgical resection.

Systematic review: gastric microbiota in health and disease

BACKGROUND

Helicobacter pylori is the most infamous constituent of the gastric microbiota and its presence is the strongest risk factor for gastric cancer and other gastroduodenal diseases. Although historically the healthy stomach was considered a sterile organ, we now know it is colonised with a complex microbiota. However, its role in health and disease is not well understood.

AIM

To systematically explore the literature on the gastric microbiota in health and disease as well as the gut microbiota after bariatric surgery.

METHODS

A systematic search of online bibliographic databases MEDLINE/EMBASE was performed between 1966 and February 2019 with screening in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Randomised controlled trials, cohort studies and observational studies were included if they reported next-generation sequencing derived microbiota analysis on gastric aspirate/tissue or stool samples (bariatric surgical outcomes).

RESULTS

Sixty-five papers were eligible for inclusion. With the exception of H pylori-induced conditions, overarching gastric microbiota signatures of health or disease could not be determined. Gastric carcinogenesis induces a progressively altered microbiota with an enrichment of oral and intestinal taxa as well as significant changes in host gastric mucin expression. Proton pump inhibitors usage increases gastric microbiota richness. Bariatric surgery is associated with an increase in potentially pathogenic proteobacterial species in patient stool samples.

CONCLUSION

While H pylori remains the single most important risk factor for gastric disease, its capacity to shape the collective gastric microbiota remains to be fully elucidated. Further studies are needed to explore the intricate host/microbial and microbial/microbial interplay.

The expression of gastrointestinal differentiation markers in extrahepatic cholangiocarcinoma: clinicopathological significance based on tumor location

The expression of gastrointestinal differentiation markers is associated with the tumorigenesis and prognosis of digestive cancers. However, little is known about the significance of gastrointestinal differentiation marker profiles in patients with extrahepatic cholangiocarcinoma (CCA), which is classified as perihilar and distal CCA. The purpose of this study was to clarify the role of gastrointestinal differentiation marker expression in extrahepatic CCA based on tumor location. We examined the expression of gastrointestinal differentiation markers in resected perihilar (n = 30) and distal (n = 54) CCAs based on the immunohistochemical expression of the following markers: MUC2, MUC5AC, MUC6, CD10, CDX-2, and cytokeratin 20. Expression scores were determined semiquantitatively based on the rate of positively stained cells. Furthermore, we performed hierarchical clustering of the CCAs based on the immunohistochemical expression scores to evaluate differences in the expression patterns of the 6 gastrointestinal differentiation markers. Consequently, perihilar and distal CCAs were stratified into 2 subgroups each. Among the perihilar CCAs, subgroup 1 was characterized by lower expression of MUC5AC and MUC6, a larger median tumor size, and a significantly worse prognosis compared with subgroup 2. Furthermore, the immunohistological subgroup (subgroup 1 versus 2) and TNM stage (stage III versus II) were independent predictors of patient survival. Among the distal CCAs, subgroup 1 was characterized by lower expression of MUC5AC compared with subgroup 2. We suggest that gastrointestinal differentiation marker profiles are useful for stratifying perihilar and distal CCAs. In addition, gastrointestinal differentiation markers play a crucial role in tumor development, particularly in perihilar CCA.

Tandem repeats of the 5′ flanking region of human MUC5AC have a role as a novel enhancer in MUC5AC gene expression

MUC5AC is a well-known gastric differentiation marker, which has been frequently used for the classification of stomach cancer. However, the molecular mechanism of regulation of MUC5AC expression remains to be elucidated. In previous studies, we have shown that Gli regulated MUC5AC transcription through the Gli-binding motif in the 5′ region of MUC5AC. Gli played important roles, but independently was not sufficient for MUC5AC expression. In this study, we analyzed a 4010 bp fragment of the 5′-flanking promoter region of the human MUC5AC gene by luciferase assay, and found a novel distal enhancer region located between −1434 bp to −3000 bp upstream from the first ATG initiation codon. This region is composed of repetitive DNA sequences 5′-TCACTCAC-3′. The strength of enhancer activities depended on the length of the repetitive region. The tandem repeats are conserved among primates, but not in other mammals. The tandem repeat regions enhanced promoter activities not only of MUC5AC but also of other genes. The enhancer effect of the tandem repeat regions was maintained even when inverted. ChIP analysis revealed that H3K9me3 binds to the tandem repeat regions. Together, our results suggest that the tandem repeat region in the MUC5AC promoter has the potential to act as a strong enhancer, and H3K9me3 may contribute to histone modifications of this region.

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A novel distal enhancer region is located in the MUC5AC promoter.

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The enhancer region is composed of repetitive DNA sequences 5′-TCACTCAC-3′.

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H3K9me3 bound to the tandem repeat region in the MUC5AC promoter.

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Length variants were observed in tandem repeats of the MUC5AC promoter.

Characterization of human gastric adenocarcinoma cell lines established from peritoneal ascites

The three cell lines, designated as gastric cancer (GC)1401, GC1415 and GC1436 were derived from peritoneal effusions from patients with gastric adenocarcinoma. Cell lines were established in tissue culture and in immunodeficient, non-obese diabetic/severe combined immunodeficiency (NOD/SCID) mice. All cell lines were cultured in Dulbecco's modified Eagle's medium supplemented with 5% fetal bovine serum. These cell lines were grown as an adherent monolayer with doubling time ranging between 25 h (GC1436 cell line) and 30–34 h (GC1401 and GC1415, respectively). All cells showed morphological features of epithelial-like cells, forming sheets of polygonal cells. Chromosomal analysis showed that the modal numbers ranged from 52 (GC1401), 51–56 (GC1415) and 106 (GC1436). High heterogeneity, resulting from several structural and numerical chromosomal abnormalities were evident in all cell lines. The surface marker expression suggested a tumor origin of the cells, and indicated the intestinal phenotype of a GC (CD10⁺, MUC1). All three cell lines were tumorigenic but not metastatic, in vivo, in NOD/SCID mice. The lack of metastatic potential was suggested by the lack of aldehyde dehydrogenase 1A1 activity. In conclusion, these newly established GC cell lines widen the feasibility of the functional studies on biology of GC as well as drug testing for potential therapeutic purposes.

Idiopathic Pulmonary Fibrosis: A Genetic Disease That Involves Mucociliary Dysfunction of the Peripheral Airways

Idiopathic pulmonary fibrosis (IPF) is an incurable complex genetic disorder that is associated with sequence changes in 7 genes (MUC5B, TERT, TERC, RTEL1, PARN, SFTPC, and SFTPA2) and with variants in at least 11 novel loci. We have previously found that 1) a common gain-of-function promoter variant in MUC5B rs35705950 is the strongest risk factor (genetic and otherwise), accounting for 30-35% of the risk of developing IPF, a disease that was previously considered idiopathic; 2) the MUC5B promoter variant can potentially be used to identify individuals with preclinical pulmonary fibrosis and is predictive of radiologic progression of preclinical pulmonary fibrosis; and 3) MUC5B may be involved in the pathogenesis of pulmonary fibrosis with MUC5B message and protein expressed in bronchiolo-alveolar epithelia of IPF and the characteristic IPF honeycomb cysts. Based on these considerations, we hypothesize that excessive production of MUC5B either enhances injury due to reduced mucociliary clearance or impedes repair consequent to disruption of normal regenerative mechanisms in the distal lung. In aggregate, these novel considerations should have broad impact, resulting in specific etiologic targets, early detection of disease, and novel biologic pathways for use in the design of future intervention, prevention, and mechanistic studies of IPF.

Fukutin, identified by the Escherichia coli ampicillin secretion trap (CAST) method, participates in tumor progression in gastric cancer

BACKGROUND

Gastric cancer (GC) is the fifth commonest malignancy worldwide and still one of the leading causes of cancer-related death. The aim of this study was to identify a novel prognostic marker or therapeutic target for GC.

METHODS

We analyzed candidate genes from our previous Escherichia coli ampicillin secretion trap (CAST) libraries in detail, and focused on the FKTN gene because it was overexpressed in both GC cell line CAST libraries, MKN-1 and MKN-45.

RESULTS

Quantitative reverse transcriptase PCR analysis of FKTN revealed that FKTN messenger RNA was overexpressed in nine of 28 (32.1 %) GC tissue samples compared with nonneoplastic gastric mucosa. Immunostaining of fukutin showed that 297 of 695 cases (42.7 %) were positive for fukutin. Fukutin-positive GC cases were significantly associated with differentiated histological features, and advanced T grade and N grade. In addition, fukutin expression was observed more frequently in the intestinal phenotype (51 %) of GC than in other phenotypes (37 %) when defined by the expression patterns of mucin 5AC, mucin 6, mucin 2, and CD10. FKTN small interfering RNA treatment decreased GC cell proliferation.

CONCLUSIONS

These results indicate that the expression of fukutin may be a key regulator for progression of GC with the intestinal mucin phenotype.

Concomitant neoplasms in the skin and stomach unveil the role of type IV collagen and E-cadherin in mucin core protein 5AC expression in vivo

Mucin core protein (MUC) 5AC is a gel-forming glycoprotein that is expressed in different types of tumour cells. MUC5AC expression in cultured cells is regulated through the extracellular matrix and through remodelling by other membranous proteins such as type IV collagen (COL4) and E-cadherin. However, it has not been elucidated whether COL4 and E-cadherin affect MUC5AC expression in tumours in vivo. Here, by analysing a single individual with concomitant neoplasms in the skin [extramammary Paget disease (EMPD)] and the stomach (gastric cancer), we show that MUC5AC expression is reduced in COL4 and membranous E-cadherin-expressing EMPD specimens whereas MUC5AC is not abolished in gastric cancer with COL4 negativity and E-cadherin cytoplasmic localization. As the EMPD and gastric cancer specimens were derived from a single patient, each specimen had the same genetic background. These in vivo results support previous in vitro studies which showed that COL4 and E-cadherin downregulated MUC5AC expression. Our study suggests that concomitant neoplasms in different organs of the same individual can serve as a strong tool for uncovering functional diversity in tumour markers in distinct cancer cells.

Bile acid induces MUC2 expression and inhibits tumor invasion in gastric carcinomas

PURPOSE

Bile acids might induce mucin expression and regulate tumor behavior in esophageal and colon cancers. However, little is known about the effect of bile acids on tumor invasiveness of gastric carcinoma (GC). The aim of the current study was to elucidate the mechanisms by which bile acids regulate tumor invasion in GC.

METHODS

We investigated bile acid-induced MUC2 expression and cell invasion and migration in the cultured GC cell lines, SNU-216, and MKN45. In addition, immunohistochemical analysis of MUC2 and Snail was performed on 389 archival paraffin-embedded tissues of GC to evaluate the correlation of their expression with prognosis.

RESULTS

Deoxycholic acid (DCA), a secondary bile acid, had no effect on the viability of SNU-216 and MKN45 GC cells at low concentrations (0-100 μM), but decreased viability at a higher concentration (200 μM). MKN45 cells showed higher MUC2 expression than SNU-216 cells under basal conditions. DCA treatment upregulated MUC2 mRNA expression in both SNU-216 and MKN45 cells. Expression of Snail and MMP9 was markedly decreased by DCA treatment, and E-cadherin expression was subsequently increased. DCA significantly inhibited invasion and migration of SNU-216 and MKN45 cells. In human GC, MUC2 expression showed a negative correlation with Snail expression (P = 0.021) and a significantly positive correlation with better prognosis (P = 0.023).

CONCLUSIONS

Taken together, our data suggest that DCA induced MUC2 expression in GC cells and inhibited tumor invasion and migration. Additionally, MUC2-expressing GCs showed low rates of Snail expression and were associated with a favorable prognosis.

MUC2 Expression Is Correlated with Tumor Differentiation and Inhibits Tumor Invasion in Gastric Carcinomas: A Systematic Review and Meta-analysis

Background:

While MUC2 is expressed in intestinal metaplasia and malignant lesions, the clinicopathological significance of MUC2 expression is not fully elucidated in gastric carcinoma (GC).

Methods:

The present study investigated the correlation between MUC2 expression and clinicopathological parameters in 167 human GCs. In addition, to confirm the clinicopathological significance of MUC2 expression, we performed a systematic review and meta-analysis in 1,832 GCs.

Results:

MUC2 expression was found in 58 of 167 GCs (34.7%). MUC2-expressing GC showed lower primary tumor (T), regional lymph node (N), and tumor node metastasis (TNM) stages compared with GCs without MUC2 expression (p=.001, p=.001, and p=.011, respectively). However, MUC2 expression was not correlated with Lauren’s classification and tumor differentiation. In meta-analysis, MUC2 expression was significantly correlated with differentiation and lower tumor stage (odds ratio [OR], 1.303; 95% confidence interval [CI], 1.020 to 1.664; p = .034 and OR, 1.352; 95% CI, 1.055 to 1.734; p = .017, respectively) but not with Lauren’s classification, pN stage, or pTNM stage.

Conclusions:

MUC2 expression was correlated with a lower tumor depth and lower lymph node metastasis in our study; the meta-analysis showed a correlation of MUC2 expression with tumor differentiation and lower tumor depth.

Correlations of Human Epithelial Growth Factor Receptor 2 Overexpression with MUC2, MUC5AC, MUC6, p53, and Clinicopathological Characteristics in Gastric Cancer Patients with Curative Resection

Background. The purpose of this study was to evaluate the relationships between HER2 overexpression in the tumor and MUC2, MUC5AC, MUC6, and p53 status and clinicopathological characteristics of gastric cancer patients. Methods. This retrospective study included 282 consecutive patients with gastric cancer who underwent surgery at the Kosin University Gospel Hospital between April 2011 and December 2012. All tumor samples were examined for HER2 expression by immunohistochemistry (IHC) and MUC2, MUC5AC, MUC6, and p53 expression by staining. A retrospective review of the medical records was conducted to determine the correlation between the presence of HER2 overexpression and clinicopathological factors. Results. The HER2-positive rate was 18.1%. Although no association was found between HER2 expression and MUC5AC, the expression of MUC2, MUC6, and p53 was significantly correlated with HER2 positivity, respectively (P = 0.004, 0.037, 0.002). Multivariate analysis revealed that HER2 overexpression and nodal status were independent prognostic factors. Conclusions. HER2 overexpression in gastric carcinoma is an independent poor prognostic factor.

Gli regulates MUC5AC transcription in human gastrointestinal cells

MUC5AC is a well-known gastric differentiation marker, which has been frequently used for the classification of stomach cancer. Immunohistochemistry revealed that expression of MUC5AC decreases accompanied with increased malignant property of gastric mucosa, which further suggests the importance of MUC5AC gene regulation. Alignment of the 5′-flanking regions of MUC5AC gene of 13 mammal species denoted high homology within 200 bp upstream of the coding region. Luciferase activities of the deletion constructs containing upstream 451 bp or shorter fragments demonstrated that 15 bp region between −111 and −125 bp plays a critical role on MUC5AC promoter activity in gastrointestinal cells. We found a putative Gli-binding site in this 15 bp sequence, and named this region a highly conserved region containing a Gli-binding site (HCR-Gli). Overexpression of Gli homologs (Gli1, Gli2, and Gli3) clearly enhanced MUC5AC promoter activity. Exogenous modulation of Gli1 and Gli2 also affected the endogenous MUC5AC gene expression in gastrointestinal cells. Chromatin immunoprecipitation assays demonstrated that Gli1 directly binds to HCR-Gli: Gli regulates MUC5AC transcription via direct protein-DNA interaction. Conversely, in the 30 human cancer cell lines and various normal tissues, expression patterns of MUC5AC and Gli did not coincide wholly: MUC5AC showed cell line-specific or tissue-specific expression whereas Gli mostly revealed ubiquitous expression. Luciferase promoter assays suggested that the far distal MUC5AC promoter region containing upstream 4010 bp seems to have several enhancer elements for gene transcription. In addition, treatments with DNA demethylation reagent and/or histone deacetylase inhibitor induced MUC5AC expression in several cell lines that were deficient in MUC5AC expression. These results indicated that Gli is necessary but not sufficient for MUC5AC expression: namely, the multiple regulatory mechanisms should work in the distal promoter region of MUC5AC gene.

Distribution of LGR5+ cells and associated implications during the early stage of gastric tumorigenesis

Lgr5 was identified as a promising gastrointestinal tract stem cell marker in mice. Lineage tracing indicates that Lgr5⁺ cells may not only be the cells responsible for the origin of tumors; they may also be the so-called cancer stem cells. In the present study, we investigated the presence of Lgr5⁺ cells and their biological significance in normal human gastric mucosa and gastric tumors. RNAscope, a newly developed RNA in situ hybridization technique, specifically labeled Lgr5⁺ cells at the basal glands of the gastric antrum. Notably, the number of Lgr5⁺ cells was remarkably increased in intestinal metaplasia. In total, 76% of gastric adenomas and 43% of early gastric carcinomas were positive for LGR5. Lgr5⁺ cells were found more frequently in low-grade tumors with active Wnt signaling and an intestinal gland type, suggesting that LGR5 is likely involved in the very early stages of Wnt-driven tumorigenesis in the stomach. Interestingly, similar to stem cells in normal tissues, Lgr5⁺ cells were often restricted to the base of the tumor glands, and such Lgr5⁺ restriction was associated with high levels of intestinal stem cell markers such as EPHB2, OLFM4, and ASCL2. Thus, our findings show that Lgr5⁺ cells are present at the base of the antral glands in the human stomach and that this cell population significantly expands in intestinal metaplasias. Furthermore, Lgr5⁺ cells are seen in a large number of gastric tumors ; their frequent basal arrangements and coexpression of ISC markers support the idea that Lgr5⁺ cells act as stem cells during the early stage of intestinal-type gastric tumorigenesis.

The co-expression of functional gastric proteins in dynamic gastric diseases and its clinical significance

Background

Pepsinogen C (PGC) and mucin1 (MUC1) are important physiologically functional gastric proteins; Mucin2 (MUC2) is an “ectopic” functional protein in intestinal metaplasia of gastric mucosa. We analyzed the co-expression of the above-mentioned three proteins in dynamic gastric diseases {superficial gastritis (SG)-atrophic gastritis (AG)--gastric cancer (GC)} as well as different histological types of gastric cancer in order to find molecular phenotypes of gastric cancer and precancerous disease and further explore the potential co-function of PGC, MUC1 and MUC2 in the occurrence and development of gastric cancer.

Methods

The SG-AG-GC sequence was 57-57-70 cases in this case–control study, respectively. Different histological types of GC were 28 cases of highly and moderately differentiated aden ocarcinoma (HMDA)、30 of poorly differentiated adenocarcinoma (PDA) and 12 of mucinous adenocarcinoma (MA) or signet ring cell carcinoma (SRCC). PGC, MUC1 and MUC2 expression in situ were detected in all 184 cases using immunohistochemistry.

Results

Both PGC and MUC1 had a significantly decreased expression in GC than in SG and AG (P < 0.0001 and P < 0.01, respectively); While MUC2 had a significant increased expression in AG than in SG and GC (P < 0.0001). Seven phenotypes of PGC, MUC1 and MUC2 co-expression were found in which PGC+/MUC1+/MUC2- phenotype took 94.7%(54/57) in SG group; PGC+/MUC1+/MUC2+ and PGC-/MUC1+/MUC2+ phenotype took 43.9% (25/57) and 52.6% (30/57) in AG; the phenotypes in GC group appeared variable; extraordinarily, PGC-/MUC1-/MUC2+ phenotype took 100% (6/6) in MA or SRCC group and had a statistical significance compared with others (P < 0.05).

Conclusions

Phenotypes of PGC, MUC1 and MUC2 co-expression in dynamic gastric diseases are variable. In SG group it always showed PGC+/MUC1+/MUC2- phenotype and AG group showed two phenotypes (PGC+/MUC1+/MUC2+ and PGC-/MUC1+/MUC2+); the phenotypes in GC group appeared variable but the phenotype of PGC-/MUC1-/MUC2+ may be a predictive biomarker for diagnosing MA or SRCC, or distinguishing histological MA or SRCC from tubular adenocarcinoma accompanied by mucinous secretion or signet ring cell scattered distribution.

Mucin expression in gastric cancer: reappraisal of its clinicopathologic and prognostic significance

CONTEXT

The clinical validity of mucin expression in gastric cancer is debated. Whereas several reports demonstrate a correlation between mucin expression and prognosis, others deny such an association.

OBJECTIVES

This survival analysis study aims to elucidate the prognostic significance of mucin expression in gastric cancer.

DESIGN

A retrospective survival analysis was done with 412 cases of gastric cancer characterized on the basis of MUC immunohistochemistry using MUC2, MUC5AC, MUC6, and CD10 antibodies; the cases were divided into those with a gastric, an intestinal, or a null mucin phenotype based on the predominant mucin.

RESULTS

There was no association between mucin expression and survival when considering overall gastric cancers or the advanced gastric cancer subtype. However, early gastric cancers with a gastric mucin phenotype showed longer survival than those with an intestinal mucin phenotype (P = .01) or a null phenotype (P = .01). In particular, MUC5AC-positive early gastric cancers resulted in longer survival than did those that did not express MUC5AC (P = .009). The loss of MUC5AC expression was identified as an independent, poor prognostic factor in early gastric cancers using the Cox regression proportional hazard model (hazard ratio, 3.50; P = .045).

CONCLUSIONS

MUC5AC expression is significantly associated with patient survival and can be used to predict outcomes in the gastric cancers, especially in the early gastric cancers.

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.

MUC5AC expression correlates with invasiveness and progression of extramammary Paget's disease

BACKGROUND

Patients with in situ extramammary Paget's disease (EMPD) tend to have a good prognosis, although dermal invasion and metastasis are associated with significantly increased morbidity and mortality. Previous studies have addressed mechanisms underlying the EMPD pathogenesis; however, no molecular markers that reflect invasiveness or progression have been established.

OBJECTIVE

This study aims to identify a reliable marker for predicting the risk of invasion and metastasis in EMPD.

METHODS

We performed an initial microarray screening for in situ, invasive or metastatic lymph node lesions of EMPD. We analysed 44 specimens from 38 primary EMPD cases by immunohistochemical staining.

RESULTS

We found that expressions of MUC5AC directly correlate with invasion and prognosis. Labelling rates of tumour cells were scored by staining intensity on a four-tiered scale (- to 3+) to investigate the correlation between the expression score of these molecular markers and the type of EMPD lesion. All the specimens scored positive (3+) for MUC1 and negative (-) for MUC6. MUC5AC expression was detected in 19 of 44 (43.2%) specimens. Invasive lesions and metastatic lymph nodes tended to express MUC5AC significantly higher than in situ lesions (P < 0.01). MUC2 was positive in 10 specimens (22.7%). There was no significant difference between the degree of MUC2 expression and invasiveness.

CONCLUSION

The degree of MUC5AC expression may correlate with the invasiveness and progression of EMPD, and may be a useful marker for identifying high-risk EMPD cases.

Cathepsin E is a marker of gastric differentiation and signet-ring cell carcinoma of stomach: a novel suggestion on gastric tumorigenesis

Gastric cancer (GC) presents various histological features, though the mechanism underlying its diversity is seldom elucidated. It is mainly classified into well differentiated tubular adenocarcinoma (tub1), moderately differentiated tubular adenocarcinoma (tub2), poorly differentiated adenocarcinoma (por), signet-ring cell carcinoma (sig), mucinous adenocarcinoma (muc), and papillary adenocarcinoma (pap). By screening, we found cathepsin E (CTSE) expresses universally in sig-type, occasionally in por-type, and rarely in tub1/tub2-type GC cell lines. In surgically-resected specimens, CTSE was immunostained in 50/51 sig-type (98.0%), 3/10 tub1-type (30.0%), 7/18 tub2-type (38.9%), 15/26 por-type (57.7%), 4/10 pap-type (40.0%), and 0/3 muc-type (0.0%) GC. In endoscopically-resected specimens, 6/7 sig-type (85.7%), 7/52 tub1-type (13.7%), 5/12 tub2-type (41.7%), 2/7 pap-type (28.6%) GC and 0/6 adenoma (0.0%) expressed CTSE. For non-malignant tissues, CTSE is universally expressed in normal fundic, pyloric, and cardiac glands of stomach, but hardly in other digestive organs. In the precancerous intestinal metaplasia of stomach, CTSE is mostly observed in mixed gastric-and-intestinal type and deficient in solely-intestinal type. CTSE expression is positively correlated with gastric marker MUC5AC (p<0.0001) and negatively correlated with intestinal marker MUC2 (p = 0.0019). For sig-type GC, in both tumors and background mucosa, expression of MUC5AC and CTSE is high whereas that of MUC2 is low, indicating that sig-type GC reflects the features of background mucosa. For gastric adenoma and tub1/tub2-type GC, more undifferentiated tumors tend to show higher expression of CTSE with MUC5AC and lower expression of MUC2 in tumors, but they tend to present lower expression of CTSE, MUC5AC and MUC2 in background mucosa. These suggest that more malignant gastric adenocarcinoma with stronger gastric and weaker intestinal properties tend to arise from background mucosa with decreased both gastric and intestinal features. In conclusion, CTSE is a marker of both gastric differentiation and signet-ring cell carcinoma, which should shed light on the mechanism of gastric tumorigenesis.

HER2 expression and its clinicopathological features in resectable gastric cancer

BACKGROUND

A recent randomized controlled trial (Trastuzumab for Gastric Cancer [ToGA] study) established standard scoring criteria of human epidermal growth factor receptor 2 (HER2) for gastric cancer and demonstrated the efficacy of trastuzumab for treating metastatic gastric cancer. The aim of the present study was to evaluate the frequency of HER2-positive cases by application of the standard criteria in patients with resectable gastric cancer and to examine the relationships between HER2 expression and prognosis, mucin phenotype, p53 status, and clinicopathological features.

METHODS

A total of 213 patients were included in this retrospective study. All tumor samples were examined for HER2 expression by immunohistochemistry (IHC), HER2 amplification by in situ hybridization, and mucin and p53 expression by staining for CD10, MUC2, MUC5AC, MUC6, and p53.

RESULTS

HER2-positive tumors were identified in 25 patients (11.7 %). HER2-positive cases were more frequently found in men, older patients, and in the intestinal histological type (P = 0.0048, 0.0309, and <0.0001, respectively). Although no association was found between HER2 overexpression and mucin phenotype, the expression of CD10 and p53 was significantly correlated with HER2 positivity (P = 0.0079 and 0.013). The overall survival of HER2-negative and -positive patients was not significantly different. However, in patients with stage III/IV, overall survival was worse in HER2-positive patients (P = 0.0149). In a comparison between dual-color in situ hybridization (DISH) and fluorescence in situ hybridization (FISH), four IHC2+/3+ cases that were DISH-positive were judged as negative by FISH.

CONCLUSIONS

Our study indicated that HER2 expression was less frequent in resectable gastric cancer than in metastatic gastric cancer. The impact of HER2 expression on survival was limited. DISH was superior to FISH for evaluating cases with limited HER2 expression.

Antitumor activity of cell-permeable RUNX3 protein in gastric cancer cells

PURPOSE

Gastric cancer is a leading cause of cancer death worldwide. Limited therapeutic options highlight the need to understand the molecular changes responsible for the disease and to develop therapies based on this understanding. The goal of this study was to develop cell-permeable (CP-) forms of the RUNT-related transcription factor 3, RUNX3-a candidate tumor suppressor implicated in gastric and other epithelial cancers-to study the therapeutic potential of RUNX3 in the treatment of gastric cancer.

EXPERIMENTAL DESIGN

We developed novel macromolecule transduction domains (MTD) which were tested for the ability to promote protein uptake by mammalian cells and tissues and used to deliver of biologically active RUNX3 into human gastric cancer cells. The therapeutic potential CP-RUNX3 was tested in the NCI-N87 human tumor xenograft animal model.

RESULTS

RUNX3 fusion proteins, HM(57)R and HM(85)R, containing hydrophobic MTDs enter gastric cancer cells and suppress cell phenotypes (e.g., cell-cycle progression, wounded monolayer healing, and survival) and induce changes in biomarker expression (e.g., p21(Waf1) and VEGF) consistent with previously described effects of RUNX3 on TGF-β signaling. CP-RUNX3 also suppressed the growth of subcutaneous human gastric tumor xenografts. The therapeutic response was comparable with studies augmenting RUNX3 gene expression in tumor cell lines; however, the protein was most active when administered locally, rather than systemically (i.e., intravenously).

CONCLUSIONS

These results provide further evidence that RUNX3 can function as a tumor suppressor and suggest that practical methods to augment RUNX3 function could be useful in treating of some types of gastric cancer.

Gastric carcinoma with invasive micropapillary pattern and its association with lymph node metastasis

AIMS

This study aimed to characterize the clinicopathological features of invasive micropapillary carcinoma (IMPC) of the stomach.

METHODS AND RESULTS

Seventeen cases of gastric IMPC were identified from histological reviews of 1178 consecutive cases. IMPC components occupied 10-90% of the entire tumours. Fifteen tumours showed invasion into the muscularis propria or deeper, whereas two tumours were limited to the submucosa. All 17 cases were associated with tubular or papillary adenocarcinoma. Lymphatic and venous invasion were identified more frequently in cases with IMPC components than in those without (P = 0.0023 and P = 0.0009, respectively). Nodal metastases were identified in 14 of 17 (82%) cases with IMPC components, whereas they were detected in 540 of 1161 (47%) cases with no IMPC components (P = 0.0053). Multivariate analysis demonstrated that the presence of IMPC was an independent predictor of nodal metastasis.

CONCLUSIONS

Conservative treatments, such as endoscopic resection, should not be used for gastric carcinoma with IMPC components, as these cases are associated with a high propensity for lymphovascular invasion and nodal metastasis.

Histopathological phenotypes of early gastric cancer and its background mucosa

Recent advances in endoscopic submucosal dissection (ESD) techniques contribute to endoscopic treatment of early gastric cancer (EGC). Recognition of chronic atrophic gastritis as the background is important for high-quality detection and diagnosis of EGC. But, relationships between EGC and atrophy of the background gastric mucosa caused by Helicobacter pylori are not well understood. The present study demonstrated histopathological phenotypes of EGC, as well as chronic atrophic gastritis as background mucosa of EGC. We evaluated mucosal heights, number of glands, and degree of intestinal metaplasia (IM) of the background gastric mucosa, using 81 cases of EGC resected by ESD. Gastric phenotype cancer cases showed IM of the background gastric mucosa less frequently, compared with intestinal phenotype cancer cases (score of IM, 1.15 vs. 1.65, P = 0.012). The average mucosal heights around EGC were lower in moderately to poorly differentiated adenocarcinoma cases than well differentiated adenocarcinoma cases (442.6 µm vs. 500.2 µm, P = 0.011). The mucosal atrophy indicated by average heights of background mucosa was low in the gastric phenotype cancer cases, compared with the intestinal phenotype cancercases (452.8 µm vs. 505.6 µm, P = 0.018). In the fundic gland area, the mucosal heights were low in the gastric phenotype cancer cases, compared with the intestinal phenotype cancer cases (413.2 µm vs. 495.5 µm, P = 0.015). Our results using EGC specimens indicated that gastric phenotype cancer and moderately to poorly differentiated adenocarcinoma had atrophic background mucosa with lower mucosal heights and less IM. The atrophic gastric mucosa with less IM is thought to play an important role in gastric carcinogenesis, especially tumoriogenesis of gastricphenotype cancer.

Clinicopathological analysis of early-stage gastric cancers detected after successful eradication of Helicobacter pylori

BACKGROUND AND AIMS

The results of a randomized controlled study and meta-analysis study have recently proved that Helicobacter pylori eradication has a preventive effect against the development of metachronous and primary gastric cancer. However, gastric cancer is sometimes detected after successful eradication. There is a lack of study about gastric cancers in eradicated patients. To clarify the characteristics of gastric cancers detected after H. pylori eradication, we analyzed the clinicopathological features of these cancers.

METHODS

The subjects were 18 early-stage gastric cancer specimens resected from 17 patients who had received successful eradication of H. pylori from February 1995 to March 2009. The control group consisted of 36 specimens from noneradicated patients with persistent H. pylori infection who were matched with the subjects in age, sex, and depth of invasion. Clinicopathological features and mucin phenotypes of gastric cancer were clinically and immunohistologically evaluated.

RESULTS

The average diameter of gastric cancer was smaller and Ki-67 index was lower in the eradication group. The morphological distribution of depression types was significantly lower in the control group. Immunohistochemical phenotyping revealed that 72.2% of the lesions in the eradicated group were complete gastric type or gastric predominant mixed type, whereas the percentages of gastric type and intestinal type in the control group were similar.

CONCLUSION

Our findings indicate that the clinicopathological characteristics of gastric cancers detected after H. pylori eradication are different from those of gastric cancers in patients with persistent H. pylori infection. H. pylori eradication may suppress intestinalization during the development of gastric cancer.

Molecular analysis of gastric differentiated-type intramucosal and submucosal cancers

Identification of the molecular characteristics of intramucosal (IMCs) and submucosal cancers (SMCs) is essential to our understanding of early gastric carcinogenesis. However, little is known regarding the differences between the 2 lesions. One hundred and forty-eight patients with primary early gastric cancer [IMC, 106; SMC, 42] were characterized for expression of cell cycle-related proteins and loss of heterozygosity (LOH). We also examined microsatellite instability (MSI) and methylation status. For LOH and methylation studies, we used a panel of 17 microsatellite markers (3p, 4p, 5q, 9p. 13q, 17p, 18q and 22q) and promoter regions of 9 genes (MLH-1, RUNX3, p16, HPP1, RASSF2A, SFRP1, DKK-1, ZFP64 and SALL4) that are frequently altered or methylated in gastric cancers. Overexpression of p53 and cyclin D1 was observed in SMC. In addition, low expression of p27 was more frequent in SMC than in IMC. Frequencies of 4p, 9p, 13q and 22q were significantly higher in SMC than in IMC. The SALL4 gene was frequently methylated in SMC compared with IMC. However, other gene methylations were common in both IMC and SMC. The frequency of LOH-high status/methylation-low status was significantly higher in SMC than in IMC. However, LOH-low status/methylation-high status in SMC was more frequently found in IMC. Our data confirm that methylation of cancer-related genes plays a major role in the development of IMCs. Importantly, the results also show that gastric submucosal progression is characterized by the accumulation of specific genetic alterations. In addition, changes of cell cycle-related proteins are associated with cancer progression.

Short rare MUC6 minisatellites-5 alleles influence susceptibility to gastric carcinoma by regulating gene

The human MUC6 gene, which is reported to be expressed in the stomach and gall bladder, is clustered on chromosome 11p15.5 with other secreted mucins. In this study, the genomic structure of MUC6 has been analyzed and five VNTR (minisatellites; MS1-MS5) were identified. These minisatellites were analyzed in genomic DNA extracted from 1,103 controls, 470 gastric cancer patients, and multigenerational families. Five novel minisatellites were found to be polymorphic and transmitted through meiosis by Mendelian inheritance in families. We evaluated allelic variation in these minisatellites to determine if such variation affected the susceptibility to gastric cancer. A significant association (odds ratio [OR]=7.08) between short rare MUC6-MS5 alleles and relative risks were observed for gastric cancer (95% confidence interval [CI], 1.43-35.19; P=0.005). To investigate the function of minisatellite alleles of MUC6-MS5, we examined the effects on gene expression from luciferase reporters when inserted with minisatellites. Interestingly, when the shortest allele (7TR) was inserted in the promoter, the expression level decreased over 20-fold (P<0.001) in normal and cancer cell lines. Furthermore, the cancer-specific rare allele (TR8) also showed decreased expression levels in cancer cells. Therefore, we suggest that the short rare MUC6-MS5 alleles may be related to cancer development by the regulation of MUC6 expression.

MUC2 and MUC6 apomucins expression in human gastric neoplasm: an immunohistochemical analysis

Apomucins play important biological roles in cell-cell and cell-extracellular matrix interactions, in cell signaling, and in biological properties of cancer cells. Their specific pattern of expression during the different steps of tumor progression toward adenocarcinoma suggests that they play significant roles in tumorigenesis. The family of secreted mucins, gel-forming components of viscoelastic mucus gels protecting the epithelia, includes mucins MUC2 and MUC6. Their principle function is to contribute in mucus formation by forming a tridimensional network via oligomerization domains to protect underlying epithelia against diverse injuries. The current study was investigated the expression of MUC2 and MUC6 in patients with gastric carcinoma. MUC2 and MUC6 expressions were detected immunohistochemically in gastric cancer biopsies using specific monoclonal antibodies. The results showed that in our gastric carcinoma cases, MUC2 expression was detected in 78.6% of cases. MUC2 expression is increased from well differentiated to moderately differentiated to poorly differentiated gastric adenocarcinoma. On the other hand, MUC6 was detected in 32% of cases. The expression of MUC2 is increasing, which is accompanied by an altered expression of MUC6 in gastric cancer. Therefore, it is concluded that the expression pattern of secreted mucins including MUC2 and MUC6 is altered apparently in gastric carcinoma.

A case of extrahepatic bile duct wall recurrence of gastric carcinoma that was treated with pancreaticoduodenectomy

We report on a patient with obstructive jaundice caused by recurrence of gastric carcinoma in the wall of an extrahepatic bile duct more than 5 years after gastrectomy who was treated with pancreaticoduodenectomy. Histopathologic examination of the surgically resected specimen revealed a poorly differentiated adenocarcinoma with focal signet ring cells in the wall of the common bile duct which was histologically similar to the primary gastric carcinoma. To confirm the diagnosis, immunohistochemical staining was performed with antibodies against cytokeratins (CK7, CK20) and mucin peptide core antigens (MUC5AC, MUC6, MUC2). Based on the expression patterns of this monoclonal antibody panel, the final diagnosis of the common bile duct tumor was an isolated local recurrence of the gastric carcinoma. The patient has survived for more than 26 months after pancreaticoduodenectomy without recurrence.

Risk factors in malignant transformation of gastric epithelial neoplasia categorized by the revised Vienna classification: endoscopic, pathological, and immunophenotypic features

BACKGROUND

According to the revised Vienna classification, the surgical removal of gastric epithelial neoplasia category 3 (low-grade dysplasia) lesions is not necessary, whereas the removal of category 4 lesions (high-grade dysplasia and intramucosal cancer) is obligatory. However, approximately 15%-30% of low-grade adenomas/dysplasia progress to high-grade lesions or adenocarcinoma, and it is difficult to determine which lesions will advance to true malignancy. The aim of this study was to evaluate the endoscopic, pathological, and immunophenotypic differences between category 3 and 4 lesions according to the revised Vienna classification.

METHODS

All tissue samples were excised by endoscopic mucosal resection. Fifty-two category 3 tissue samples and 54 category 4 samples were evaluated by endoscopic findings; by pathology examination of the surrounding mucosa; and by CD10, MUC2, MUC5AC, MUC6, and RUNX3 immunohistochemical staining.

RESULTS

Univariate analysis showed that the size of the lesion, color change, ulceration, gastritis score of the surrounding mucosa, and positive expression of MUC6 were associated with category 4 lesions. Multivariate analysis showed that the size of the lesion, ulceration, and positive expression of MUC6 were strongly associated with category 4 lesions.

CONCLUSION

Lesions more than 17 mm in diameter or lesions that are associated with ulceration have the potential for malignant transformation. Positive immunoreactivity for MUC6 appears to be a complementary marker for malignant transformation of gastric epithelial neoplasia.

Comparison between colorectal low- and high-grade mucinous adenocarcinoma with MUC1 and MUC5AC

AIM: To explore useful prognostic factors for mucinous adenocarcinoma (MAC) in the colon and rectum.

METHODS: MAC was divided into low- and high-grade types based on the degree of structural differentiation; low-grade MAC arisen from well to moderately differentiated adenocarcinoma and papillary carcinoma, and high-grade MAC from poorly differentiated adenocarcinoma and signet ring cell carcinoma. Immunohistochemically, the expression of 2 types of MUC1 (MUC1/DF and MUC1/CORE), MUC2, 2 types of MUC5AC (MUC5AC/CHL2 and HGM), MUC6, CDX2, and CD10 was examined in 16 cases of MAC consisting of 6 low- and 10 high-grade types.

RESULTS: MUC1/DF3 was expressed in 3 of 6 low-grade MAC (50%) and 10 of 10 high-grade MAC (100%). MUC1/CORE was expressed in 1 of 6 low-grade MAC (16.7%) and 7 of 10 high-grade MAC (70%). MUC2 was expressed in all MAC regardless of the grade. MUC5AC was expressed in 6 of 6 low-grade MAC (100%) and 4 of 10 high-grade MAC (40%). HGM was expressed in 5 of 6 low-grade MAC (83.3%) and 6 of 10 high-grade MAC (60%). Expression of MUC6 and CD10 was undetected in all MAC regardless of the grade. CDX2 was expressed in 5 of 6 low-grade MAC (83.3%) and 7 of 10 high-grade MAC (70%). Taken together, MUC1/DF3 was expressed significantly more frequently in high-grade MAC than in low-grade, and MUC5AC/CHL2 was expressed significantly more frequently in low-grade MAC than in high-grade.

CONCLUSION: It is proposed that MUC1/DF3 and MUC5AC/CHL2 immunostaining is useful to discriminate high-grade MAC from low-grade MAC.

Molecular pathology of RUNX3 in human carcinogenesis

A major goal of molecular biology is to elucidate the mechanisms underlying cancer development and progression in order to achieve early detection, better diagnosis and staging and novel preventive and therapeutic strategies. We feel that an understanding of Runt-related transcription factor 3 (RUNX3)-regulated biological pathways will directly impact our knowledge of these areas of human carcinogenesis. The RUNX3 transcription factor is a downstream effector of the transforming growth factor-beta (TGF-beta) signaling pathway, and has a critical role in the regulation of cell proliferation and cell death by apoptosis, and in angiogenesis, cell adhesion and invasion. We previously identified RUNX3 as a major gastric tumor suppressor by establishing a causal relationship between loss of function and gastric carcinogenesis. More recently, we showed that RUNX3 functions as a bona fide initiator of colonic carcinogenesis by linking the Wnt oncogenic and TGF-beta tumor suppressive pathways. Apart from gastric and colorectal cancers, a multitude of epithelial cancers exhibit inactivation of RUNX3, thereby making it a putative tumor suppressor in human neoplasia. This review highlights our current understanding of the molecular mechanisms of RUNX3 inactivation in the context of cancer development and progression.

Epstein-Barr virus-associated gastric carcinoma: a distinct carcinoma of gastric phenotype by claudin expression profiling

Epstein-Barr virus (EBV)-associated gastric carcinoma (GC) is a distinct subtype with characteristic clinicopathological features. To better characterize its cellular characteristics, 43 cases of EBV-associated GC, 68 cases of EBV-negative GC, and non-neoplastic gastric mucosa in adults and fetuses were examined immunohistochemically. We quantified the expression of the major tight-junction protein claudin (CLDN) -1, -3, -4, -7, and -18 together with gastric mucins (MUC5AC and MUC6), intestinal mucin (MUC2), and CD10. EBV-associated GC showed a high frequency of CLDN18 expression (84%) and a low frequency of CLDN3 expression (5%). This expression profile corresponded to that of normal gastric epithelium in adults and fetuses. Almost half of the EBV-associated GC cases demonstrated gastric mucin expression, whereas the other half lacked mucin or CD10 expression. In contrast, as demonstrated by the expression profiles of CLDN3 and CLDN18, EBV-negative GC comprised a heterogeneous group of four different CLDN phenotypes: gastric, intestinal, mixed, and an undifferentiated type with variable expression patterns of mucins. These results indicate that EBV-associated GC is considerably homogenous with regard to cellular differentiation and that it preserves well the nature of the cells of origin. EBV-associated GC may undergo distinct carcinogenic processes, which differ from those of EBV-negative GC.

Construction of the specific MUC5AC-siRNA expression plasmid and effect of siRNA on proliferation and apoptosis in human bile duct cancer line HCCC-9810

AIM: To observe specific siRNA silencing effect on Mucin-5 subtype AC gene in human intrahepatic cholangiocarcinoma cell line HCCC-9810 as well as to investigate the influence on proliferation and apoptosis after silencing the Mucin-5 subtype AC gene.

METHODS: Three pairs of specific MUC5AC-siRNA were designed and synthesized through transcription in vitro. Three different siRNA expression plasmids (pRNAT-U6.1/Neo-MUC5AC-siRNA1/2/3) were constructed by gene recombination. Then three stable expression plasmids and the comparison plasmid (empty plasmid-transfected control) were transfected into HCCC-9810 by liposome-mediated transfection. Transfection efficiency was evaluated by nonspecific small molecular siRNA (fluorescent conjugate). MUC5AC-mRNA level was detected by RT-PCR. Expression of Mucin-5 subtype AC was investigated by immunohistochemical SABC method. Cell apoptosis and proliferation were analyzed by flow cytometry and MTT, respectively.

RESULTS: The results of gene sequencing indicated that the pRNAT-U6.1/Neo-MUC5AC-siRNA1/2/3 was successfully constructed. After the transfection, the efficiency of fluorescent protein expression reached 28.57%; the results of RT-PCR and immunocytochemistry showed that constructed plasmids down-regulated mRNA and protein of Mucin-5 subtype AC at 48 h after transfection. The results of MTT indicated that the growth of HCCC-9810 was obviously inhibited after silencing the Mucin-5 subtype AC gene. Apoptosis was induced in the tumor cells after suppressing the expression of Mucin-5 subtype AC gene by flow cytometry.

CONCLUSION: Three different stable expression plasmids of siRNA specific for Mucin-5 subtype AC gene obviously inhibit the expression at MUC5AC-mRNA and protein level. The blockage of Mucin-5 subtype AC gene expression in HCCC-9810 cells shows significant effect on cell apoptosis and proliferation.