Cell kinetics and genetic instabilities in differentiated type early gastric cancers with different mucin phenotype

Correlation of Claudin18.2 expression with clinicopathological characteristics and prognosis in gastric cancer

OBJECTIVES

Claudin18.2 (Cldn18.2) is a tight junction protein expressed in gastric epithelial cells and is an emerging target for gastric cancer (GC). This study aimed to analyze the correlation between Cldn18.2 and clinicopathological parameters in GC patients undergoing radical surgery.

METHODS AND RESULTS

This study included 426 GC patients who underwent radical gastrectomy. The expression of Cldn18.2 was analyzed by immunohistochemical staining and grading. The statistical results indicated that the expression of Cldn18.2 was correlated with T stage, TNM stage, Lauren classification, and the expression level of Mucin-2 (MUC2), Mucin-5AC (MUC5AC), Mucin-6 (MUC6), human epidermal growth factor receptor 2 (HER2), P53 and trefoil factor 2 (TFF2). In addition, through data mining of the Cancer Genome Atlas (TCGA) database, it is suggested that Cldn18.2 expression level is significantly correlated with the expression level of MUC5AC, MUC6, and TFF2. Besides, Cldn18.2 is related to tumor immune infiltration, programmed cell death protein 1 (PD 1) pathway, cell cycle and Wnt signaling pathway.

CONCLUSIONS

The expression of Cldn18.2 was closely related to gastric-type GC, so gastric-type GC patients may benefit more from targeted drugs targeting Cldn18.2. In GC cells, depletion of Cldn18.2 may influence cell cycle and immune response by affecting Wnt signaling pathway and PD 1 pathway.

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.

Molecular alterations and PD-L1 expression in non-ampullary duodenal adenocarcinoma: Associations among clinicopathological, immunophenotypic and molecular features

Non-ampullary duodenal adenocarcinoma (NADC) is extremely rare. Little is known about its clinicopathological and molecular features or its management. Herein we retrospectively analyzed the cases of 32 NADC patients, focusing on microsatellite instability (MSI), genetic mutations, CpG island methylator phenotype (CIMP), and immunostaining including mucin phenotype and PD-L1 expression. The incidence of MSI, KRAS/BRAF/GNAS mutations and CIMP was 51.6%, 34.4%/3.1%/6.5% and 28.1%, respectively. PD-L1 expression was seen in 34.4% of patients. No significant associations between clinicopathological features and KRAS/BRAF/GNAS genetic mutations or CIMP were found. Histologically non-well-differentiated-type NADCs and those in the 1st portion of the duodenum were significantly associated with later stages (stages III–IV) (P = 0.006 and P = 0.003, respectively). Gastric-phenotype NADCs were frequently observed in the 1st portion and in late-stage patients; their cancer cells more frequently expressed PD-L1. Histologically, the non-well-differentiated type was an independent predictor of PD-L1 expression in cancer cells (OR 25.05, P = 0.04) and immune cells (OR 44.14, P = 0.02). Only late-stage disease (HR 12.23, P = 0.01) was a prognostic factor for worse overall survival in a Cox proportional hazards regression model. Our observation of high proportions of MSI and PD-L1 expression may prompt the consideration of immune checkpoint inhibitors as a new treatment option for NADCs.

Autofluorescence Imaging Reflects the Nuclear Enlargement of Tumor Cells as well as the Cell Proliferation Ability and Aberrant Status of the p53, Ki-67, and p16 Genes in Colon Neoplasms

BACKGROUND

Autofluorescence imaging (AFI) is useful for diagnosing colon neoplasms, but what affects the AFI intensity remains unclear. This study investigated the association between AFI and the histological characteristics, aberrant methylation status, and aberrant expression in colon neoplasms.

METHODS

Fifty-three patients with colorectal neoplasms who underwent AFI were enrolled. The AFI intensity (F index) was compared with the pathological findings and gene alterations. The F index was calculated using an image analysis software program. The pathological findings were assessed by the tumor crypt density, cell densities, and N/C ratio. The aberrant methylation of p16, E-cadherin, Apc, Runx3, and hMLH1 genes was determined by a methylation-specific polymerase chain reaction. The aberrant expression of p53 and Ki-67 was evaluated by immunohistochemical staining.

RESULTS

An increased N/C ratio, the aberrant expression of p53, Ki-67, and the altered methylation of p16 went together with a lower F index. The other pathological findings and the methylation status showed no association with the F index.

CONCLUSIONS

AFI reflects the nuclear enlargement of tumor cells, the cell proliferation ability, and the altered status of cell proliferation-related genes, indicating that AFI is a useful and practical method for predicting the dysplastic grade of tumor cells and cell proliferation.

CHARACTERIZATION OF THE MUCIN PHENOTYPE CAN PREDICT GASTRIC CANCER RECURRENCE AFTER ENDOSCOPIC MUCOSAL RESECTION

BACKGROUND

Endoscopic mucosal resection is still considered an accepted treatment for early gastric cancer for selected cases. Histopathologic criteria for curative endoscopic resection are intramucosal well-differentiated adenocarcinoma, lateral and deep margins free of tumor, no histological ulceration, and no venous or lymphatic embolism. A 5% local recurrence rate has been described even when all the above-mentioned criteria are met. On the other hand, antigen expression by tumoral cells has been related to the biological behavior of several tumors.

OBJECTIVE

To evaluate whether early gastric cancer mucin immunoexpression, p53 and Ki-67, can predict recurrence after endoscopic mucosal resection, even when standard histopathologic criteria for curative measures have been attempted.

METHODS

Twenty-two patients with early gastric cancer were considered to have been completely resected by endoscopic mucosal resection. Local recurrence occurred in 5/22 (22.7%). Immunohistochemical study was possible in 18 (81.8%) resected specimens. Patients were divided in two groups: those with and those without local recurrence. They were compared across demographic, endoscopic, histologic data, and immunohistochemical factors for MUC2, MUC5a, CD10, p53, and Ki-67.

RESULTS

Mucin immunoexpression allowed a reclassification of gastric adenocarcinoma in intestinal (10), gastric (2), mixed (4), and null phenotypes (2). Mixed phenotype (positive for both MUC2 and MUC5a) was found in 80% of cases in the local recurrence group, while the intestinal type (positive MUC2 and negative MUC5a) was found in 76.9% of cases without local recurrence (P=0.004). Other observed features did not correlate with neoplastic recurrence.

CONCLUSION

The mixed phenotype of early gastric adenocarcinoma is associated with a higher probability of local recurrence after endoscopic mucosal resection.

Predictive factors for lymph node metastasis in early gastric cancer with lymphatic invasion after endoscopic resection

BACKGROUND

Lymph node (LN) metastasis is found in only about 5-10% of the patients who undergo additional surgery after non-curative endoscopic resection. Lymphatic invasion after endoscopic submucosal dissection (ESD) is regarded as non-curative resection due to risk of reginal LN metastasis. This study was aimed to identify clinicopathologic predictive factors for LN metastasis in early gastric cancer (EGC) with lymphatic invasion after endoscopic resection.

METHODS

Among a total of 2036 patients who underwent endoscopic resection for EGC at Samsung Medical Center from April 2000 to May 2011, 146 patients were diagnosed with lymphatic invasion. And 123 patients who had gastrectomy with LN dissection due to presence of lymphatic invasion as one of the non-curative factors were included in this study. Demographics, endoscopic tumor findings, histological findings, surgical findings with pathologic reports, and follow-up data were collected from the patient's medical records. Pathological re-evaluation of resected specimens was performed.

RESULTS

Among a total of 123 patients, LN metastases were found in seven patients (5.7%). The univariate analysis revealed that the LN metastasis was significantly more frequent in patients with certain morphology of lymphatic invasion that shows adhesion to endothelium of lymphatic tumor emboli (p = 0.016), higher number of lymphatic tumor emboli in whole section (p < 0.001) and papillary adenocarcinoma component (p = 0.024). In multivariate analysis, the number of lymphatic tumor emboli [OR 93.5, 95% CI (2.62-3330.81)] and the presence of papillary adenocarcinoma component [OR 552.5, 95% CI (1.20-254871.81)] were identified as independent predictors of LN metastasis in patients with lymphatic invasion after endoscopic resection.

CONCLUSIONS

The number of lymphatic tumor emboli and the presence of papillary adenocarcinoma component were significant predictors for LN metastasis in patients with lymphatic invasion after endoscopic resection.

Clinicopathologic and molecular characteristics of gastric cancer showing gastric and intestinal mucin phenotype

Gastric cancer (GC), one of the most common human cancers, can be classified into gastric or intestinal phenotype according to mucin expression. TP53 mutation, allelic deletion of the APC gene and nuclear staining of β-catenin are frequently detected in the intestinal phenotype of GC, whereas CDH1 gene mutation, microsatellite instability and DNA hypermethylation of MLH1 are common events in the gastric phenotype of GC. Our Serial Analysis of Gene Expression (SAGE) and Escherichia coli ampicillin secretion trap (CAST) analyses revealed that CDH17, REG4, OLFM4, HOXA10, DSC2, TSPAN8 and TM9SF3 are upregulated in GC and that CLDN18 is downregulated in GC. Expression of CDH17, REG4, HOXA10 and DSC2 and downregulation of CLDN18 are observed in the intestinal phenotype of GC. In contrast, OLFM4 is expressed in the gastric phenotype of GC. Expression of TSPAN8, TM9SF3 and HER2 are not associated with either gastric or intestinal phenotypes. Ectopic CDX2 expression plays a key function in the GC intestinal phenotype. MUC2, CDH17, REG4, DSC2 and ABCB1 are direct targets of CDX2. Importantly, these genes encode transmembrane/secretory proteins, indicating that the microenvironment as well as cancer cells are also different between gastric and intestinal phenotypes of GC.

Clinical significance of a papillary adenocarcinoma component in early gastric cancer: a single-center retrospective analysis of 628 surgically resected early gastric cancers

BACKGROUND

We recently reported that the presence of a papillary adenocarcinoma (pap) component was an independent risk factor for lymphatic involvement in endoscopically resected early gastric cancer (EGC). This study aimed to investigate the potential association between the presence of a pap component in EGC and lymph node metastasis (LNM).

METHODS

In order to evaluate the association between LNM and clinicopathological features, including a pap component, we reviewed 628 surgically resected EGCs at our institution between 2009 and 2012. Clinicopathological features included age, gender, tumor location, macroscopic type, tumor size, histological type, depth, ulcerative findings, and lymphatic and venous involvement. In addition, the association between clinicopathological features and lymphatic involvement was also evaluated.

RESULTS

LNM was observed in 52 cases (8.3%). Univariate analyses revealed a significant correlation between a pap component and LNM as well as tumor size, depth, macroscopic type, a poorly differentiated adenocarcinoma component, and lymphatic and venous involvement. The percentage of positive LNM among the EGC cases with a pap component was significantly higher than in those without the component (18.2 vs. 7.3%, P = 0.010). Via multivariate analyses lymphatic involvement was identified as the strongest risk factor for LNM [odds ratio (OR) 14.1] and a pap component was revealed as an independent risk factor for lymphatic involvement (OR 3.1).

CONCLUSION

Our study revealed that EGC cases with a pap component were at higher risk of lymphatic involvement and showed a higher percentage of positive LNM. More attention should be paid to a pap component in EGC.

Assessment of gastric phenotypes using magnifying narrow-band imaging for differentiation of gastric carcinomas from adenomas

Background. Conventional white-light endoscopy and forceps biopsy are insufficient for definitive diagnosis of gastric adenoma. Immunohistochemical studies have reported an obvious phenotypic difference between adenomas and carcinomas. We investigated the utility of narrow-band imaging with magnifying endoscopy (NBI-ME) for mucin phenotypic assessment to differentiate carcinomas from adenomas. Methods. NBI-ME findings were classified into A, B, and AB types, which revealed papillary, tubular pits and groove microstructures, respectively. To investigate A-B classifications retrospectively, 137 patients (155 lesions) that were diagnosed pretherapeutically with adenoma or borderline lesions by biopsy were enrolled. The mucin phenotype was analyzed immunohistochemically in the first 60 lesions. Results. After endoscopic submucosal dissection, A type and AB type lesions were determined histologically as carcinoma (81/82, 99%). B type lesions were adenoma (29/73, 40%) and carcinoma (44/73, 60%). A or AB type correlated to histological carcinomas (sensitivity 65%, specificity 97%, and accuracy 71%). Mucin phenotypes were gastric or gastrointestinal in A type and AB type carcinomas (31/37, 84%) and intestinal in B type adenomas and carcinomas (21/23, 91%). Conclusions. NBI-ME has the advantage of the assessment of mucin phenotypes in gastric carcinomas and adenomas. The proposed A-B classification is useful, especially for differentiation of gastric or gastrointestinal carcinomas from adenomas.

Molecular markers of mucosa harboring gastric adenomas

CONTEXT

Gastric adenoma is a precursor lesion of the adenocarcinoma.

OBJECTIVE

To characterize gastric adenomas according to the mucin immunoexpression and to evaluate the immunoexpression of p53, p16ink4a, BCL-2, cyclin D, Ki-67, in the adenoma and in the gastric mucosa harboring adenoma.

METHODS

Forty gastric specimens from 20 patients were classified as intestinal (MUC2-goblet cell mucin) or foveolar (MUC5AC-gastric-foveolar mucin) adenomas. Immunohistochemistry was performed using streptavidin-biotin-complex method.

RESULTS

Twelve (60%) patients were men. The mean age was 67.9±12.9 years-old. Intestinal adenomas were detected in 13 (65%) patients and gastric type in 7 (35%). Low-grade dysplasia was present in 13 (65%) of the adenomas, high-grade in 3 (15%), and adenocarcinoma within the polyp in 4 (20%). Six (30%) patients had synchronous adenocarcinoma. p53 immunoexpression was observed in 6/20 (30%) of adenomas, and in 2/6 (33.3%) of synchronous tumors. There was an association between p53 immunoexpression and intestinal type of adenoma/tumor, P=0.04. There was no association between p16ink4a, Bcl-2, cyclin D and Ki-67 and adenoma clinicopathological characteristics.

CONCLUSION

Immunohistochemistry may be useful to classify the adenomas subtypes and may define the pathway of adenoma to carcinoma sequence.

Exocrine and endocrine modulation in common gastric carcinoma

Diagnostic and prognostic implications of endocrine differentiation were evaluated in 103 common gastric adenocarcinomas and undifferentiated carcinomas. Maturely differentiated exocrine and endocrine phenotypes were evaluated by using gastric exocrine and endocrine markers along with intestinal exocrine and endocrine markers. Immunohistochemical analysis revealed that 66 tumors (64%) were positive for generic endocrine markers such as chromogranin A and/or synaptophysin. The 14 patients with more than 20% tumor cells positive for at least 1 endocrine marker experienced a poorer prognosis than patients with no (n = 37) or 1% to 20% (n = 52) positivity. The 16 carcinomas expressing the maturely differentiated exocrine gastric phenotype significantly correlated with poorer outcome compared with carcinomas with mature exocrine intestinal (n = 22) or mixed/gastrointestinal (n = 64) phenotypes. Among tumors expressing chromogranin A and/or synaptophysin, the maturely differentiated endocrine gastric phenotype (n = 26) was a negative prognostic factor compared with mature endocrine intestinal (n = 21) and mixed/gastrointestinal (n = 5) phenotypes. Endocrine differentiation and maturely exocrine/endocrine gastric phenotypes are associated with an unfavorable prognosis and may identify subsets of patients for tailored therapy.

Molecular pathology of gastric cancer: research and practice

Recent advances in the understanding of molecular stomach carcinogenesis are reviewed. As to molecular events in individual mucin phenotypes of gastric cancer, the CDX2-Reg IV-SOX9 pathway is associated with the intestinal mucin phenotype, while OLFM4 and CLDN18 are novel markers for the gastric phenotype. microRNAs play an important role in epigenetic deregulation in gastric cancer. Many microRNAs are up-regulated and down-regulated, and some of these are associated with histological differentiation and cancer progression. Reduced miR-200 may participate in the genesis of diffuse type gastric cancer by reducing E-cadherin expression. Genetic polymorphism is a crucial endogenous cause and a fundamental factor of cancer risk. PSCA polymorphism alters the susceptibility to diffuse type gastric cancer through modulation of cell proliferation activity. Cancer stem cells possess the capacity for self-renewal and cause the heterogeneous lineages of cancer cells. Cancer stem cells also show resistance to anti-tumor chemotherapy. Only a minor population of gastric cancer cells reveals the properties of cancer stem cells, and CD44 is one of the markers for gastric cancer stem cells. The origin of gastric cancer stem cells remains to be elucidated.

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.

Relationship between clinicopathological features and mucin phenotypes of advanced gastric adenocarcinoma

AIM

To investigate a relationship between the clinicopathological features and mucin phenotypes in advanced gastric adenocarcinoma (AGA).

METHODS

Immunohistochemical staining was performed to determine the mucin phenotypes in 38 patients with differentiated adenocarcinomas (DACs), 9 with signet-ring cell carcinomas (SIGs), and 48 with other diffuse-type adenocarcinomas (non-SIGs) of AGA. The mucin phenotypes were classified into 4 types: gastric (G), gastrointestinal (GI), intestinal, and unclassified.

RESULTS

The G-related mucin phenotypes were highly expressed in all the histological subtypes of AGA. The expression of the GI phenotype in SIG patients was lower than that in DAC patients (P = 0.02), and this phenotype was observed in 56% of the non-SIG patients in the intramucosal layer. Among non-SIG cases, the expression of the GI phenotype was significantly higher in patients with extended adenocarcinomas and those with positive rates of lymph node metastasis. There was no difference between the expressions of the G and other GI phenotypes factors. Among DAC and non-SIG patients, there were no differences between the survival rates of the corresponding patient groups.

CONCLUSION

The GI phenotype might possess more invasive characteristics than the G phenotype in non-SIG. Neither of the phenotypes indicated a poor prognosis of DAC and non-SIG.

Differences in genetic instability and cellular phenotype among Barrett's, cardiac, and gastric intestinal metaplasia in a Japanese population with Helicobacter pylori

AIMS

Intestinal metaplasia is considered to be a precursor lesion in both Barrett's and intestinal-type gastric cancer. The aim was to clarify the differences in molecular pathology between specialized intestinal metaplasia (SIM) in Barrett's oesophagus (BO), cardiac (CIM) and gastric intestinal metaplasia (GIM).

METHODS AND RESULTS

Eighty-eight SIM cases with BO, 30 CIM cases and 52 GIM cases in patients with or without Helicobacter pylori infectionwere analysed for genetic instability and Das-1. Microsatellite instability and a loss of heterozygosity were evaluated at five microsatellite loci. The incidence of genetic instability was 55.7% in SIM, 40.0% in CIM and 23.1% in GIM, revealing a significant difference between SIM and GIM (P < 0.0005). For each microsatellite marker analysed, there were obvious differences in frequency among the three conditions. Das-1 reactivity was significantly higher in SIM than in CIM or GIM (P < 0.0001, both). Interestingly, both genetic instability and Das-1 reactivity in SIM showed a significantly higher incidence in patients with H. pylori infection than in those without (P < 0.005 and P < 0.01, respectively).

CONCLUSIONS

SIM is distinct from CIM and GIM, and the pathogenesis of SIM, like that of GIM, is associated to some degree with H. pylori infection in a Japanese population.

Transcriptome dissection of gastric cancer: identification of novel diagnostic and therapeutic targets from pathology specimens

Gastric cancer is the fourth most common malignancy in the world, and mortality due to gastric cancer is second only to that from lung cancer. 'Transcriptome dissection' is a detailed analysis of the entire expressed transcripts from a cancer, for the purpose of understanding the precise molecular mechanism of pathogenesis. Serial analysis of gene expression (SAGE) is a suitable technique for performing transcriptome dissection. Gastric cancers of different stages and histology were analyzed on SAGE, and one of the largest gastric cancer SAGE libraries in the world was created (GEO accession number GSE 545). Through SAGE, many candidate genes have been identified as potential diagnostic and therapeutic targets for the treatment of gastric cancer. Regenerating islet-derived family, member 4 (Reg IV) participated in 5-fluorouracil (5-FU) resistance and peritoneal metastasis, and its expression was associated with an intestinal phenotype of gastric cancer and with endocrine differentiation. GW112 expression correlated with advanced tumor stage. Measurement of Reg IV and GW112 levels in sera indicated a sensitivity of 57% for detection of cancer. SPC18 participated in tumor growth and invasion through transforming tumor growth factor-alpha upregulation. Palate, lung, and nasal epithelium carcinoma-associated protein (PLUNC) was a useful marker for gastric hepatoid adenocarcinoma. Expression of SOX9, HOXA10, CDH17, and loss of claudin-18 expression were associated with an intestinal phenotype of gastric cancer. Information obtained from transcriptome dissection greatly contributes to diagnosis and treatment of gastric cancer.

Predictive factors for local recurrence and incomplete resection of early gastric cancer treated by endoscopic resection: a Western experience

BACKGROUND

Early gastric cancer (EGC) is defined as adenocarcinoma limited to the mucosa or submucosa regardless of lymph node involvement. Local EGC recurrence rates have been described in up to 6% of cases.

OBJECTIVES

To evaluate predictive factors for incomplete resection and local recurrence of EGC treated by endoscopic mucosal resection (EMR) that was followed up for at least one year.

METHODS

From June 1994 to December 2005, 46 patients with EGC underwent EMR. Possible predictive factors for incomplete endoscopic resection and local recurrence were identified by medical chart analysis. Demographic, endoscopic and histopathological data were retrospectively evaluated. EMR was considered complete or incomplete. Patients from the complete resection group were divided into subgroups (with and without local EGC recurrence).

RESULTS

Complete resection was possible in 36 cases (76.6%). Predictive factors for incomplete resection were tumour location (P=0.035), histological type (P=0.021), lesion size (P=0.022) and number of resected fragments (P=0.013). On multivariate analysis, undifferentiated histological type (OR 0.8; 95% CI 0.036 to 0.897) and number of resected fragments (OR 7.34; 95% CI 1.266 to 42.629) were independent predictive factors for incomplete resection. In the complete resection group, a larger lesion size was associated with a higher the number of resected fragments (P=0.018). Local recurrence occurred in nine cases (25%). Use of the cap technique was the only predictive factor for local recurrence in five of seven cases (71.4%) (P=0.006).

CONCLUSIONS

A larger lesion size was associated with a higher number of resected fragments. Undifferentiated adenocarcinoma and piecemeal resection were predictive factors for incomplete resection. Technique type was a predictive factor for local EGC recurrence.

Unclassified mucin phenotype of gastric adenocarcinoma exhibits the highest invasiveness

BACKGROUND AND AIM

Gastric cancers present with distinctive carcinogenesis pathways that vary with the mucin phenotypes. We attempted to elucidate the relations between the characteristics of the mucin phenotypes of gastric cancer and the tumor invasiveness.

METHODS

Gastric adenocarcinomas that were resected surgically between August 2005 and April 2007 were included in the present study. The gastric cancers were subclassified into gastric and intestinal mucin phenotypes if more than 10% of cancer cells exhibited gastric (MUC5AC and/or MUC6) and intestinal (MUC2 or CD10) markers, respectively.

RESULTS

The mucin phenotypes of 123 gastric cancers were gastric (n = 31), intestinal (n = 43), mixed (n = 28) and unclassified (n = 21). The mucin phenotype was related to histological type (P < 0.001), Lauren's classification (P = 0.001) and size (P = 0.014) of the gastric adenocarcinoma, but not to its location or to the presence of Helicobacter pylori infection. The unclassified mucin phenotype exhibited the largest number of lymph node metastases (P = 0.007), lymphatic invasions (P < 0.001) and neural invasions (P = 0.026), whereas the intestinal mucin phenotype exhibited the lowest invasiveness.

CONCLUSION

The mucin phenotype reflects the biological behavior of gastric cancer, with the intestinal and unclassified mucin phenotypes exhibiting the lowest and highest invasiveness, respectively.

Effects of Helicobacter pylori infection on genetic instability, the aberrant CpG island methylation status and the cellular phenotype in Barrett's esophagus in a Japanese population

Genetic or epigenetic alterations in Barrett's esophagus (BE) with/without Helicobacter pylori (H. pylori) infection remain unclear. We examined the effects of H. pylori infection on genetic instability (GIN), the CpG island methylation status and a biomarker related to BE carcinogenesis. We analyzed 113 Japanese individuals with endoscopically suspected BE. The patients included, Group CLE (n = 25): no specialized intestinal metaplasia (SIM) in a columnar lined epithelium (control); Group BE (n = 88): all had SIM. Microsatellite instability and a loss of heterozygosity as GIN, the methylation status at hMLH1, E-cadherin, p16 and APC, and immunoreactivity using a monoclonal antibody (mAb) Das-1, which specifically reacts with BE, were evaluated. Nine additional patients with BE were prospectively followed up for 2 years after successful H. pylori eradication. The frequency of GIN, methylation at E-cadherin and APC, and mAb Das-1 reactivity in Group BE was significantly higher than that in Group CLE (p < 0.0001, p < 0.0001 and p < 0.005, and p < 0.0001, respectively). Furthermore, GIN, E-cadherin methylation and mAb Das-1 reactivity showed a significantly higher incidence in patients with H.pylori infection than in those without H. pylori infection (p < 0.01, p < 0.005, and p < 0.01, respectively). Interestingly, the patients from Group BE were observed to change to a stable state of molecular alterations in 60% for GIN, 42.9% for E-cadherin methylation and 55.6% for APC methylation, or a reduction of mAb Das-1 reactivity was noted in 25% following eradication. H. pylori infection may therefore affect these molecular alterations associated with the pathogenesis of BE, to some degree, in the Japanese population.

Clinicopathological and prognostic significance of mucin phenotype in gastric cancer

BACKGROUND AND OBJECTIVES

Gastric and intestinal mucin phenotype cell markers are widely expressed in gastric carcinoma cells, irrespective of their tumor histological type. In the present study, we tried to reveal the clinicopathological significance of mucin phenotype in human gastric carcinomas. Moreover, we investigated the clinical significance of RUNX3 in association with mucin phenotype.

METHODS

The mucin expression of MUC5AC, MUC6, MUC2, and CD10 was evaluated in 97 gastric carcinomas by immunohistochemistry. Tumors were classified into gastric (G), gastric and intestinal mixed (GI), intestinal (I), and null (N) phenotype according to combination of mucin expression.

RESULTS

The rate of G, GI, I, and N phenotype was 40.0%, 38.1%, 10.3%, and 19.6%, respectively. Mucin phenotype was also significantly correlated with several clinicopathological findings. Patients with I phenotype had a significantly poorer prognosis than those with any other phenotypes. They also had a higher rate of postoperative liver metastasis. Multivariate analysis revealed that mucin phenotype was a significant independent prognostic factor. We suggested that Loss of RUNX3 expression might correlate with intestinal phenotype and postoperative outcome.

CONCLUSIONS

Mucin phenotype has a significant prognostic value and may be a useful marker for the treatment of human gastric carcinoma.

Quantitative analysis of the effect of Helicobacter pylori on the expressions of SOX2, CDX2, MUC2, MUC5AC, MUC6, TFF1, TFF2, and TFF3 mRNAs in human gastric carcinoma cells

OBJECTIVE

To investigate the phenotypic characters of carcinoma cells and the response of gastric epithelial cells to Helicobacter pylori (H. pylori) infection using the gastric carcinoma cell lines.

MATERIAL AND METHODS

Real-time reverse transcription-polymerase chain reaction (RT-PCR) was used to assess the effect of H. pylori infection on mRNA levels of transcription factors (SOX2 and CDX2), mucin core proteins (MUC2, MUC5AC, and MUC6), and trefoil factor family peptides (TFF) (TFF1, TFF2, and TFF3) in gastric carcinoma cells (AGS, MKN45, and KATO III cells). H. pylori ATCC 43504 and its isogenic cag pathogenicity island (PAI) deleted mutant were used.

RESULTS

These cell lines expressed mixed gastric and intestinal phenotypes. The intestinal phenotype predominated in AGS cells and gastric phenotypes in MKN45 and KATO III cells. In all three cell lines, H. pylori infection inhibited SOX2 mRNA expression, but induced the three TFFs mRNAs. In AGS cells, H. pylori induced cag PAI-dependent mRNA expression of CDX2, MUC2, MUC5AC, and MUC6. mRNA expressions of CDX2, MUC5AC, and MUC6 were inhibited in KATO III cells, whereas MUC2 mRNA expression was unchanged. In MKN45 cells, H. pylori induced the three MUCs mRNAs but inhibited CDX2 mRNA expression.

CONCLUSIONS

This study provides a useful platform for selecting appropriate cell lines to model H. pylori-related changes in the gastric epithelium that mirror the changes seen in vivo. The outcome of H. pylori infection may reflect changes in the mucus gel layer caused by altered expression of mucins and TFF peptides.

Gastric and intestinal phenotypic marker expression in early differentiated-type tumors of the stomach: clinicopathologic significance and genetic background

PURPOSE

Gastric and intestinal phenotypic cell markers are expressed in gastric carcinomas, irrespective of their histologic type. In the present study, we determined the clinicopathologic significance of phenotypic marker expression in early-stage gastric differentiated-type tumors and the association between marker expression and genetic alterations.

EXPERIMENTAL DESIGN

Phenotypic marker expression was determined by examining the expressions of human gastric mucin (HGM), MUC6, MUC2, and CD10 in 63 gastric adenomas, 133 early differentiated-type carcinomas, and 24 follow-up cases with gastric adenoma. Tumors were classified into gastric, gastric and intestinal mixed, or intestinal phenotypes according to the immunopositivity of the above markers. The presence of mutations in APC, K-ras, and p53 and the microsatellite instability status were also determined in all tumors.

RESULTS

The expressions of HGM and MUC6, representing gastric or gastric and intestinal mixed phenotypes, were significantly associated with high-grade atypia in the 63 gastric adenomas. Among the 133 early differentiated-type carcinomas, HGM expression was significantly associated with mixed-type (with an undifferentiated-type component) tumors and lymph node metastasis. MUC2 expression was inversely associated with submucosal invasion. A multivariate analysis revealed that gastric adenomas were significantly associated with the intestinal phenotype and were inversely associated with p53 mutation compared with early differentiated-type carcinomas. Among all 196 tumors, APC mutation was significantly associated with CD10 expression and the intestinal phenotype and was inversely associated with the expressions of HGM and MUC6. The microsatellite instability status was significantly associated with MUC6 expression. Malignant transformation from gastric adenoma to carcinoma was shown in 5 of the 24 follow-up cases of gastric adenoma. The malignant transformation was significantly associated with the gastric and intestinal mixed phenotype and was inversely associated with APC mutation. No malignant transformation was found in intestinal phenotype gastric adenomas with APC mutation.

CONCLUSIONS

Our present findings show that phenotypic marker expression is associated with tumor aggressiveness during the early stage of gastric differentiated-type tumors. Differences in the biological behavior of tumors with different phenotypes may result from differences in the genetic backgrounds during the incipient phase of gastric tumorigenesis.

Assessment of microsatellite instability status for the prediction of metachronous recurrence after initial endoscopic submucosal dissection for early gastric cancer

The technique of endoscopic submucosal dissection (ESD) has been developed for en bloc resection of early gastric cancer (EGC); however, little is known about the risk of metachronous cancer in the remnant stomach after initial ESD. In this study, we investigated the correlation between microsatellite instability (MSI) status and the incidence of metachronous recurrence of gastric cancer. According to the genetic/molecular background determined with MSI status and expression levels of hMLH1 and p53 tumour suppressor, 110 EGCs removed with ESD were subclassified into three groups: the mutator/MSI-type (8%), suppressor/p53-type (45%) and unclassified type (47%). Interestingly, patients with the mutator/MSI-type tumour had a high incidence (67%) of metachronous recurrence of gastric cancer within a 3-year observation after initial ESD, which was significantly higher than those with the suppressor/p53-type and unclassified type tumours (P<0.01). Although we investigated mucin phenotypes, there was no correlation between mucin phenotype and the recurrence of EGC. These findings suggest that subclassification of molecular pathological pathways in EGCs is required for the assessment of patients with a high risk of recurrent gastric cancer. The information delivered from our investigation is expected to be of value for decisions about therapy and surveillance after ESD.

Molecular characteristics of differentiated-type gastric carcinoma with distinct mucin phenotype: LI-cadherin is associated with intestinal phenotype

Gastric carcinomas (GC) are classified into four phenotypes on the basis of the mucin expression profile: G type (gastric or foveolar phenotype), I type (intestinal phenotype), GI type (intestinal and gastric mixed phenotype) and N type (neither gastric nor intestinal phenotype). Immunohistochemistry was used to examine the expression of epidermal growth factor receptor (EGFR), E-cadherin, liver-intestine (LI)-cadherin, CD44v9 and p53 and correlation of these molecules with mucin phenotype and tumor stage was evaluated. Overexpression of EGFR and LI-cadherin, reduced expression of E-cadherin and abnormal expression of p53 were observed more frequently in advanced GC than in early GC. Among I-type GC, overexpression of EGFR and reduced expression of E-cadherin were observed more frequently in advanced tumors than in early tumors. Among G-type GC, reduced expression of E-cadherin was significantly associated with advanced tumors. With respect to the relationship between mucin phenotype and expression of cancer-related molecules, overexpression of LI-cadherin was observed more frequently in I-type (12/25, 48.0%) than in G-type (1/14, 7.1%) GC. I-type GC tended to express LI-cadherin more frequently than GI-type GC. These results provide insights into the molecular characteristics of the distinct mucin phenotype of differentiated-type GC and suggest that LI-cadherin may contribute to the biological behavior of I-type GC.

Tumor differentiation phenotype in gastric differentiated-type tumors and its relation to tumor invasion and genetic alterations

AIM: To clarify the relations between tumor differentiation phenotype and tumor invasion or genetic alterations in gastric differentiated-type tumors.

METHODS: We examined the tumor differentiation phenotype, the presence of mutations in APC and p53, and the microsatellite instability (MSI) status in 48 gastric adenomas and 171 differentiated-type carcinomas. The tumor differentiation phenotype was determined by examining the expression of human gastric mucin (HGM), MUC6, MUC2 and CD10. The tumors were then classified into gastric- (G-), gastric and intestinal mixed- (GI-), or intestinal- (I-) phenotypes, according to the immunopositivity of the above markers. The presence of mutations in APC and p53 and the MSI status were also investigated in all the tumors.

RESULTS: Gastric adenomas were significantly associated with CD10 expression, I-phenotype tumors and the presence of APC mutations, compared with carcinomas (66.7% vs 25.1%, P < 0.0001; 56.3% vs 14.6%, P < 0.0001; 39.6% vs 14.0%, P < 0.0001, respectively) and inversely associated with expressions of HGM and MUC6 and the presence of p53 mutations (10.4% vs 62.6%, P < 0.0001; 39.6% vs 64.3%, P = 0.003; 2.0% vs 26.3%, P = 0.001, respectively). The frequency of APC mutations was significantly higher in HGM-negative tumors, MUC6-negative tumors, CD10-positive tumors and I-phenotype tumors than in HGM-positive tumors, MUC6-positive tumors, CD10-negative tumors and G-phenotype tumors (32.7% vs 7.1%, P < 0.0001; 27.8% vs 14.0%, P = 0.0182; 37.3% vs 10.4%, P < 0.0001; and 38.5% vs 9.5%, P = 0.0017, respectively). The frequency of MSI was significantly higher in MUC6-positive tumors, CD10-negative tumors and G-phenotype tumors than in MUC6-negative tumors, CD10-positive tumors and I-phenotype tumors (24.8% vs 6.7%, P = 0.0009; 22.2% vs 8.0%, P = 0.0143; and 28.6% vs 9.6%, P = 0.0353, respectively).

CONCLUSION: The tumor differentiation phenotype is closely related to tumor invasion and genetic alterations in gastric differentiated-type tumors.

Differential caspase-3 expression in noncancerous, premalignant and cancer tissues of stomach and its clinical implication

BACKGROUND

Caspase-3 is a critical apoptosis-promoting element but its status during stepwise gastrocarcinogenesis needs to be further clarified.

MATERIALS AND METHODS

By the use of frozen tissue microarrays constructed with the tissue spots cored from defined histological regions in tissue blocks, the pattern of caspase-3 expression in noncancerous, premalignant (atrophic gastritis and intestinal metaplasia) tissue and cancer spots were analyzed under the same experimental conditions by the methods of immunohistochemistry and mRNA-in situ hybridization.

RESULTS

Caspase-3 was expressed in all 34 of the noncancerous mucosa (100%), in 16 of the 17 premalignant tissues (94.1%) and in 15 of the 48 gastric cancers (31.3%). The incidences of caspase-3 detection were significantly different (p<0.01) between noncancerous mucosa and intestinal as well as diffuse gastric cancers.

CONCLUSION

Down-regulated caspase-3 is closely correlated with gastric cancer formation and would be a potential indicator of tumor formation and progression. Helicobacter pylori (H. pylori; Hp) infection is but not the only one element responsible to the enhanced caspase-3 expression in gastric epithelia.

Gastric and intestinal phenotypic cell marker expressions in gastric differentiated-type carcinomas: association with E-cadherin expression and chromosomal changes

Gastric and intestinal phenotypic cell markers are widely expressed in gastric carcinomas, irrespective of their histological type. In the present study, the relations between the phenotypic marker expression of the tumour, histological findings, expression of cell adhesion molecules, and the chromosomal changes in gastric differentiated-type carcinomas were examined. The phenotypic marker expression of the tumour was determined by the combination of the expression of the human gastric mucin (HGM), MUC6, MUC2 and CD10, and was evaluated in comparison with the expression of cell adhesion molecules, such as E-cadherin and beta-catenin, and chromosomal changes by comparative genomic hybridization (CGH) in 34 gastric differentiated-type carcinomas. Tumours were classified into the gastric- (G-), gastric and intestinal mixed- (GI-), intestinal- (I-), or unclassified- (UC-) phenotype according to the immunopositivity of staining for HGM, MUC6, MUC2, and CD10. G-phenotype tumours were significantly associated with a higher incidence of differentiated-type tumours mixed with undifferentiated-type component, compared with GI- and I-phenotype tumours (88.9 vs 33.3%, P=0.0498 and 88.9 vs 42.9%, P=0.0397; respectively). HGM-positive tumours were significantly associated with a higher incidence of tumours with abnormal expression of E-cadherin, compared with HGM-negative tumours (66.7 vs 21.1%, P=0.0135). GI-phenotype tumours were significantly associated with a higher incidence of tumours with abnormal expression of E-cadherin, compared with I-phenotype tumours (77.8 vs 21.4%, P=0.0131). HGM-negative tumours were significantly associated with higher frequencies of the gains of 19q13.2 and 19q13.3, compared with HGM-positive tumours (57.9 vs 20.0%, P=0.0382 and 63.2 vs 13.3%, P=0.0051; respectively). MUC6-positive tumours were significantly associated with higher frequencies of the gains of 20q13.2, compared with MUC6-negative tumours (71.4 vs 30.0%, P=0.0349). MUC2-positive tumours were significantly associated with the gain of 19p13.3, compared with MUC2-negative tumours (41.2 vs 5.9%, P=0.0391). I-phenotype tumours were significantly associated with higher frequencies of gains of 5p15.2 and 13q33-34, compared with G-phenotype tumours (66.7 vs 0%, P=0.0481, each) and also associated with higher frequencies of gain of 7p21, compared with GI-phenotype tumours (66.7 vs 0%, P=0.0481). Our present results show that gastric differentiated-type carcinomas have different characteristics according to the phenotypic marker expression of the tumour in terms of histological findings, E-cadherin expression and pattern of chromosomal changes.

Microsatellite instability is linked to loss of hMLH1 expression in advanced gastric cancers: lack of a relationship with the histological type and phenotype

BACKGROUND

It has been suggested that the prevalence of microsatellite instability (MSI) is high in intramucosal differentiated gastric cancers with gastric foveolar phenotypic expression, and that these tumors are prone to lose their glandular structures and progress to undifferentiated-type lesions. To test this hypothesis, we examined the relationships among human MutL homologue 1 (hMLH1) expression (which is linked to MSI), the phenotype, and the histological type in patients with advanced and intramucosal gastric cancer.

METHODS

We analyzed hMLH1 expression by immunohistochemistry in 70 advanced and 30 intramucosal gastric cancers with histological evaluation and assessment of the phenotype, and Cdx2 expression determined by immunohistochemistry. The MSI status was also examined in 20 cases.

RESULTS

Thirteen (18.6%) advanced and 5 (16.7%) intramucosal gastric cancers were judged to be hMLH1-negative. In the advanced cases, no association was observed between the histological type and the phenotype and loss of hMLH1. In the intramucosal cases, MUC5AC expression was observed in all 5 hMLH1-negative differentiated-type cancers. However, no hMLH1-negative lesions were detected in the intramucosal undifferentiated cancers (0/14; P < 0.05 vs differentiated types). In the advanced cases, MSI-positivity (MSI +) and loss of hMLH1 expression did correlate (P < 0.0001), while no association was observed between MSI +, histological type, and phenotype.

CONCLUSION

Our data support the hypothesis that, phenotypically, some MSI-positive differentiated gastric cancers of gastric foveolar phenotypic expression may easily change, from gastric to intestinal phenotypic expression, also changing, histologically, from differentiated to undifferentiated type with progression.

Gene deregulation in gastric cancer

Despite its decreasing frequency in the Western world during recent decades, gastric cancer is still one of the leading causes of cancer-related deaths worldwide. Due to the oligosymptomatic course of early gastric cancer, most cases are diagnosed in the advanced stages of the disease. The curative potential of current standard treatment continues to be unsatisfactory, despite multimodal approaches involving surgery, chemotherapy and radiotherapy. Novel therapeutics including small molecules and monoclonal antibodies are being developed and have been partially introduced into clinical use in connection with neoplastic diseases such as chronic myeloid leukemia, non-Hodgkin's lymphoma and colorectal cancer. Thorough understanding of the changes in gene expression occurring during gastric carcinogenesis may help to develop targeted therapies and improve the treatment of this disease. Novel molecular biology techniques have generated a wealth of data on up- and down-regulation, activation and inhibition of specific pathways in gastric cancer. Here, we provide an overview of the different aspects of aberrant gene expression patterns in gastric cancer.

DNA methylation profiles of differentiated-type gastric carcinomas with distinct mucin phenotypes

Gastric carcinomas (GC) are classified into four phenotypes according to mucin expression. Previous studies revealed the association of distinct genetic profiles in GC with mucin phenotypic expression; however, the roles of epigenetic changes, such as DNA methylation, are poorly understood. We examined whether the phenotypic expression of GC was associated with DNA methylation of hMLH1, MGMT, p16(INK4a), RAR-beta or CDH1. Expression of HGM, M-GGMC-1, MUC2, and CD10 was analyzed immunohistochemically in 33 advanced GC with differentiated histology. HGM was expressed in 14 (42.4%) cases, M-GGMC-1 in five (15.2%) cases, MUC2 in 15 (45.5%) cases and CD10 in 18 (54.5%) cases. DNA methylation was detected in five (15.2%) cases for hMLH1, 11 (33.3%) cases for MGMT, 13 (39.4%) cases for p16(INK4a), 17 (51.5%) cases for RAR-beta and 14 (42.4%) cases for CDH1 by bisulfite-polymerase chain reaction and methylation-specific polymerase chain reaction. DNA methylation of hMLH1 occurred more frequently in MUC2-negative GC than in MUC2-positive GC (P = 0.0488, Fisher's exact test). In contrast, MGMT was more frequently methylated in MUC2-positive GC than in MUC2-negative GC (P = 0.0078, Fisher's exact test). There was no correlation between gastric or intestinal-markers and methylation of the p16(INK4a), RAR-beta and CDH1 genes. These results indicate that DNA methylation of specific genes, such as hMLH1 and MGMT, may be involved partly in the distinct phenotypic expression of GC.

Gastric and intestinal phenotypic marker expression in gastric carcinomas and recurrence pattern after surgery-immunohistochemical analysis of 213 lesions

Both gastric and intestinal phenotypic markers are known to be expressed in gastric carcinomas, irrespective of their histologic type. In the present study, the relation between gastric and intestinal phenotypic marker expression in gastric carcinomas and the recurrence pattern after surgery was examined. The phenotypic marker expression of the tumour was determined by examining the expression of human gastric mucin (HGM), MUC6, MUC2 and CD10 in 213 advanced gastric carcinomas in 213 patients who had undergone a curative resection (97 died from recurrent gastric carcinoma and 116 were alive without recurrence at the end of the follow-up period). Tumours were classified into gastric (G), gastric and intestinal mixed (GI), intestinal (I) or unclassified (UC) phenotypes according to the immunopositivity of HGM, MUC6, MUC2 and CD10 stainings. The incidence of HGM-positive tumours and MUC2-negative tumours was significantly higher in tumours with peritoneal recurrence than in tumours without recurrence (73.3%, 44 out of 60 cases vs 54.3%, 63 out of 116 (P=0.022); and 70.0%, 42 out of 60 vs 38.8%, 45 out of 116 (P=0.0002), respectively). The incidence of G-phenotype tumours was also significantly higher in tumours with peritoneal recurrence than in tumours without recurrence (58.3%, 35 out of 60 cases vs 28.4%, 33 out of 116 (P=0.0002)). The incidence of MUC2-negative tumours and CD10-positive tumours was significantly higher in tumours with haematogenous recurrence than in tumours without recurrence (62.5%, 20 out of 32 cases vs 38.8%, 45 out of 116 (P=0.028); and 43.8%, 14 out of 32 vs 23.3%, 27 out of 116 (P=0.039); respectively). Our present findings show that the gastric and intestinal phenotypic marker expression of the tumour, determined by immunohistochemical staining for HGM, MUC6, MUC2 and CD10, can be used to predict the pattern of gastric carcinoma recurrence after curative resection.