MUC6 expression is a preferable prognostic marker for invasive mucinous adenocarcinoma of the lung.

Gastric gland mucin consists of core protein MUC6 with residues heavily glycosylated by unique O-glycans carrying α1,4-linked N-acetylglucosamine (αGlcNAc). αGlcNAc-glycosylated MUC6 protein is seen in normal gastric and duodenal glands. Decreased αGlcNAc glycosylation on MUC6-positive tumor cells is often observed in premalignant lesions of the stomach, pancreas, and bile duct, and decreased MUC6 expression is seen in invasive cancer of these organs. Lung cancer (LC) is the most common cause of cancer death worldwide. Recently, the adenocarcinoma subtype has become the most common histological subtype of LC, and one of its invasive forms is invasive mucinous adenocarcinoma (IMA). Currently, prognostic markers of LC IMA are unknown. Here, we analyzed MUC5AC, MUC6, and αGlcNAc expression in 54 IMA LC cases. MUC5AC was positively expressed in 50 (93%), MUC6 in 38 (70%), and αGlcNAc in 19 (35%). Each expression level was scored from 0 to 3. The αGlcNAc expression score was significantly decreased relative to MUC6 (P < 0.001). Interestingly, disease-free survival was significantly higher in MUC6-positive than MUC6-negative cases based on the log-rank test (P = 0.021). For in vitro analysis, we ectopically expressed MUC6 in A549 cells, derived from LC and harboring a KRAS mutation. MUC6-expressing A549 cells showed significantly lower proliferation, motility, and invasiveness than control cells. Finally, F-actin staining in MUC6-expressing cells revealed a decrease or loss of filopodia associated with decreased levels of FSCN transcripts, which encodes an actin-bundling protein fascin1 necessary for cell migration. We conclude that MUC6 expression is a preferable prognostic biomarker in IMA LC.

Molecular Alterations in Gastric Preneoplastic Lesions and Early Gastric Cancer.

Prognosis of gastric cancer is dramatically improved by early diagnosis. Correa's cascade correlates the expression of some molecular markers with the progression of preneoplastic lesions toward carcinoma. This article reviews the diagnostic and prognostic values of molecular markers in complete (MUC2) and incomplete (MUC2, MUC5AC, and MUC6) intestinal metaplasia, gastric dysplasia/intra-epithelial neoplasia, and early gastric cancer. In particular, considering preinvasive neoplasia and early gastric cancer, some studies have demonstrated a correlation between molecular alterations and prognosis, for example, mucins phenotype in gastric dysplasia, and GATA6, TP53 mutation/LOH and MUC6 in early gastric cancer. Moreover, this review considers novelties from the literature regarding the (immuno)histochemical characterization of diffuse-type/signet ring cell gastric cancer, with particular attention to clinical outcomes of patients. The aim of this review is the evaluation of the state of the art regarding suitable biomarkers used in the pre-surgical phase, which can distinguish patients with different prognoses and help decide the best therapeutic strategy.

Gastric adenocarcinoma of fundic gland (chief cell predominant type) coexisting with well differentiated intestinal adenocarcinoma: A case report.

RATIONALE: Gastric adenocarcinoma of fundic gland (chief cell predominant type) (GA-FG-CCP) is a new, rare variant of gastric adenocarcinoma, which is characterized by mild nuclear atypia and specific immunohistochemical markers. PATIENT CONCERNS: An 84-year-old Chinese man was referred to our hospital for endoscopic resection of a gastric lesion. INTERVENTIONS: We performed endoscopic submucosal dissection, and successfully removed the lesion. DIAGNOSIS: Esophago gastroduodenoscopy showed a slightly elevated lesion with a diameter of 22 mm in the posterior wall of cardia. Magnifying endoscopy with narrow band imaging revealed an abnormal microsurface and microvessels on the tumor surface. Endoscopic ultrasonography revealed a hypoechoic mass located in the first layer. The pathological diagnosis of the biopsy specimens indicated that the tumor was high grade intraepithelial neoplasia. The pathological diagnosis differed between the superficial and deeper part of the lesion. The superficial part was composed of a tubular structure with prominent atypia and was diagnosed as well differentiated intestinal adenocarcinoma. The deeper part was composed of a well-differentiated tubular adenocarcinoma mimicking the fundic gland cells, mainly the chief cells. The tumor cells showed mild nuclear atypia and was positive for pepsinogen-I (PG-I) and mucin-6 (MUC6). This deeper part was diagnosed as GA-FG-CCP. OUTCOMES: The tumor was successfully removed. This patient had no discomfort during the follow-up period (10 months). LESSONS: We present a rare case of GA-FG-CCP coexisted with well-differentiated tubular adenocarcinoma. GA-FG-CCP exists in the deep mucosal layer and the muscularis mucosa, which could not be found under endoscopy, but could be discerned in pathology with mild nuclear atypia and special biomarkers.

Simple mucinous cyst: another potential cancer precursor in the pancreas? Case report with molecular characterization and systematic review of the literature.

Cystic lesions of the pancreas may range from benign to precursors of pancreatic cancer. Simple mucinous cyst (SMC) is larger than 1 cm, has a gastric-type flat mucinous lining, and minimal atypia without ovarian-type stroma. We report a new case of pancreatic SMC, coupling a systematic review of the English literature mainly focused on their clinic-pathological features. We reviewed 103 cases of SMC in adults (73 women), averaging 57 (range, 26-70) years. The SMCs were located in the body-tail region of the pancreas in 60 (58%) cases, presenting as single cystic lesions in 94% of cases; 43% of patients were asymptomatic. A preoperative fine-needle aspiration of the cyst fluid detected amylase and carcinoembryonic antigen positivity in 71% and 76% of cases, respectively. Patients underwent surgery mostly for suspected malignancy; in 83% of cases, a standard pancreatic resection was performed. Mean SMC size was 4.9 (range, 1.5-12.0) cm. Mucins MUC5AC and MUC6 resulted positive in 77% and 81% of cases performed, respectively, whereas MUC2 was negative in all but one patient. The SMC from our institution was characterized by a KRAS somatic mutation. The diagnosis of SMC should be considered when a solitary pancreatic cyst larger than 1 cm is detected in asymptomatic patients. To establish a correct diagnosis, an extensive histologic/immunohistochemical analysis is essential. The presence of a KRAS mutation highlights that SMC may represent another potential pancreatic cancer precursor.

Diffuse expression of MUC6 defines a distinct clinicopathological subset of pulmonary invasive mucinous adenocarcinoma.

Invasive mucinous adenocarcinoma (IMA) of the lung is a unique variant of lung adenocarcinoma. Aberrant mucin expression is associated with cancer development and metastasis. However, the clinicopathological significance of mucin expression in IMA is not fully understood. Herein, we evaluated the clinicopathological, immunohistochemical, and molecular characteristics of 70 IMA tumors. EGFR, KRAS, GNAS, and TP53 mutations were assessed by PCR-based sequencing. Next-generation sequencing was used to assess cases without EGFR/KRAS mutations. A NanoString-based screening for fusions was performed in all IMAs without mitogenic driver mutations. Expression of mucins (MUC1, MUC2, MUC4, MUC5AC, and MUC6) was evaluated by immunohistochemistry and categorized as follows: negative (<10% of tumor cells), patchy expression (<90% of tumor cells), or diffuse expression (≥90% of tumor cells). Immunohistochemical testing for transcription factors (TTF-1, CDX2, HNF1ß, HNF3α, HNF3ß, and HNF4α) was also performed. As expected, KRAS mutations were the most common (in 67% of cases), followed by small numbers of other alterations. Patchy or diffuse expression of MUC1, MUC2, MUC4, MUC5AC, and MUC6 was observed in 52% or 6%, 3% or 0%, 30% or 3%, 26% or 73%, and 59% or 27% of cases, respectively. Furthermore, all IMAs were generally positive for HNF1ß (100%), HNF3α (100%), HNF3ß (100%), and HNF4α (99%) but were positive less often for TTF-1 (6%) and CDX2 (9%). Overall, there was no significant correlation between mucin expression and transcription factor expression. Unexpectedly, diffuse expression of MUC6 was significantly associated with KRAS-wild-type tumors (p = 0.0008), smaller tumor size (p = 0.0073), and tumors in female patients (p = 0.0359) in multivariate analyses. Furthermore, patients with tumors exhibiting diffuse MUC6 expression had significantly favorable outcomes. Notably, none of these patients died of the disease. Our data suggested that diffuse expression of MUC6 defines a distinct clinicopathological subset of IMA characterized by wild-type KRAS and possibly less aggressive clinical course.

Intracholecystic tubular non-mucinous neoplasm (ICTN) of the gallbladder: a clinicopathologically distinct, invasion-resistant entity.

Preinvasive tumor-forming gallbladder neoplasms that are composed of small, non-mucinous tubules with complex architecture remain a poorly characterized group. Here, we evaluated the clinicopathological characteristics of this entity. Twenty-eight examples were analyzed. Tumors were invariably pedunculated polyps with thin stalks, often presented as loosely attached intraluminal nodules, with cauliflower architecture (akin to cholesterol polyps) comprised of compact, back-to-back acinar-like, small tubular units with minimal/no cytoplasm showing variable complexity, creating a picture distinct from the other tubular type dysplasia in the gallbladder. Their limited stroma showed distinctive amorphous amyloid-like hyalinization (39%). While some had round nuclei with single prominent nucleoli, others exhibited slightly more elongated nuclei with washed out chromatin reminiscent of papillary thyroid carcinoma. Squamoid/meningothelial-like morules (71%) and subtle neuroendocrine cell clusters (39%) were frequent. The level of cytoarchitectural atypia qualified as high-grade dysplasia (HGD) in all cases, but none were invasive. The background mucosa showed no dysplasia, but cholesterolosis. The majority (n = 8/12) showed diffuse MUC6 expression and lacked MUC5AC expression. Based on these observations, 635 gallbladder carcinomas were re-analyzed for residual/adjacent lesions with entity-defining characteristics disclosed here, and none could be identified. Preinvasive tubular non-mucinous neoplasm of the gallbladder, which we propose to classify as intracholecystic tubular non-mucinous neoplasm, is a clinicopathologically discrete entity, which tends to occur in uninjured gallbladders and in association with cholesterol polyps. By being tubular, non-mucinous and MUC6-positive, it is akin to intraductal tubulopapillary neoplasms of pancreatobiliary tract, but it is also different in many other aspects. Although their cytoarchitectural complexity warrants an HGD/carcinoma classification, they do not show invasion and their distinct characteristics warrant their separate classification.

Gastric adenocarcinoma of the fundic gland type: A case report.

INTRODUCTION: Gastric adenocarcinoma of the fundic gland type (GA-FG) is a newly described entity that is characterized by well-differentiated neoplasm with unclear etiopathogenesis. PATIENT CONCERNS: A 60-year-old Chinese man was referred to our hospital for abdominal distension. DIAGNOSIS: Esophagogastroduodenoscopy (EGD) showed a depressed lesion found using in the greater curvature of the stomach. The pathological diagnosis of the biopsy specimens indicated that the tumor was GA-FG (chief cell predominant type, GA-FG-CCP). INTERVENTIONS: Endoscopic submucosal dissection (ESD) was performed. The histopathological examination of the ESD specimen revealed gastric hyperplasia of the fundic gland type around the adenocarcinoma cells. OUTCOMES: The surgical outcomes were good. The EGD showed a scar with no recurrence, and no symptoms were observed 1 year postoperatively during the follow-up. CONCLUSION: We present a rare case of a depressed lesion with a pathogenic expression suggesting gastric hyperplasia of the fundic gland type around the adenocarcinoma cells. Considering the origin of oxyntic mucosa, we consider that it may develop into GA-FG. To understand this issue better, similar cases should be monitored in the future.

Immunohistochemical expression of HIK1083 and MUC6 in endometrial carcinomas.

AIMS: Gastric-type endocervical adenocarcinoma (EA) is characterised by aggressive behaviour and pathogenesis independent of human papillomavirus infection. Because of its morphology and frequent mutation-pattern expression of p53, gastric-type EA may be confused with several types of endometrial carcinoma, particularly in biopsy and curettage specimens. HIK1083 and MUC6 are immunohistochemical markers used to support a diagnosis of gastric-type EA; however, the rates of expression of these markers in endometrial tumours are largely unknown. We therefore aimed to assess the expression of HIK1083 and MUC6 in a cohort of different types of endometrial carcinoma. METHODS AND RESULTS: Ninety-one endometrial carcinomas (56 endometrioid, 16 clear cell, and 19 serous) from 91 patients treated with hysterectomy were included. A representative tumour block from each case was used for immunohistochemical staining with HIK1083 and MUC6. The percentage of stained cells (0-100%) and average staining intensity (weak, moderate, and strong) were recorded for both markers. None of 91 cases expressed HIK1083. In contrast, 66% (60/91) of cases showed at least focal expression of MUC6; importantly, 54 of 60 (90%) positive cases showed moderate or strong staining. Five of 60 (8%) cases showed MUC6 staining in ≥50% of tumour cells. Endometrioid tumours (49/56, 88%) were more likely to express MUC6 than cases of clear cell (1/16, 6%) or serous (10/19, 53%) carcinoma. DISCUSSION: Endometrial carcinoma often expresses MUC6. In contrast, HIK1083 is consistently negative, and thus, when positive, is a more reliable marker for distinguishing gastric-type EA from some of its endometrial mimics.

Trefoil factor family 2 protein: a potential immunohistochemical marker for aiding diagnosis of lobular endocervical glandular hyperplasia and gastric-type adenocarcinoma of the uterine cervix.

Gastric-type adenocarcinoma (GA) is an aggressive subtype of cancer of the uterine cervix. Several immunohistochemical markers for gastric mucins, such as mucin 6 (MUC6) and N-acetylglucosamine α1 → 4galactose → R (αGlcNAc-R), which is recognized by HIK1083 antibody, have been introduced for diagnosis of GA and lobular endocervical glandular hyperplasia (LEGH). However, MUC6 is also expressed in normal endocervical glands and HIK1083 antibody has limited availability. Trefoil factor family 2 protein (TFF2) is secreted by gastric, but not normal endocervical glands. Here, we evaluated TFF2 immunostaining for detection of a gastric immunophenotype in endocervical glandular lesions. We compared TFF2, αGlcNAc-R, and MUC6 expression in 103 endocervical glandular lesions: LEGH (n = 23), adenocarcinoma in situ/microinvasive adenocarcinoma (AIS-MIA) (n = 29), and invasive adenocarcinoma (usual type [UA], n = 26; GA, n = 11; intestinal type [IA], n = 2; signet ring cell type [Sig], n = 2; and mucinous adenocarcinoma not otherwise specified [NOS], n = 10). TFF2 and αGlcNAc-R expression was completely concordant in each subtype: LEGH (100%), AIS-MIA (44.8%), UA (26.9%), GA (90.9%), IA (100%), Sig (0%), and NOS (20%). TFF2 staining scores were significantly correlated with those of αGlcNAc-R in these lesions. TFF2 and αGlcNAc-R immunoreactivity was present in cytoplasmic mucins and luminal secretions. TFF2 and αGlcNAc-R were not expressed in the normal endocervical glands. MUC6 was frequently expressed in normal endocervical glands and endocervical glandular lesions. Endocervical adenocarcinomas sometimes stained only for MUC6. TFF2 is a promising immunohistochemical marker and its identification in uterine cervical secretion is a potentially useful diagnostic test for endocervical glandular lesions with gastric differentiation.

Expression of Gastric Markers Is Associated with Malignant Potential of Nonampullary Duodenal Adenocarcinoma.

BACKGROUND: Sporadic nonampullary duodenal epithelial tumors (NADETs) are uncommon, and thus their clinicopathological features have not been fully assessed. AIMS: In this study, we have analyzed a series of early sporadic NADETs, focusing on various immunohistological features. METHODS: We conducted a multicenter retrospective analysis of 68 patients with endoscopically resected sporadic NADETs. Associations between immunohistological features and clinicopathological features were statistically analyzed. RESULTS: The 68 patients consisted of 46 men (68%) and 22 women (32%) with a mean age of 60.7 ± 12.2 years (range 37-85 years). The 68 tumors were composed of 39 adenomas (57%) and 29 early-stage adenocarcinomas (43%). Duodenal adenocarcinomas were larger in size than adenomas and had papillary architecture in their pathological diagnosis with statistical significance. Duodenal adenocarcinomas also demonstrated a significantly higher expression of gastric markers (MUC5AC and MUC6) and a higher MIB-1 index. Duodenal adenomas were contrastively apt to express intestinal markers (MUC2, CDX1 and CDX2). Of the 68 cases analyzed, there were only 3 tumors positive for p53 staining, all of which were adenocarcinoma. When 7 submucosal invasive cancers and 21 intramucosal cancers were compared, submucosal invasion was positively associated with expression of MUC5AC. Also, submucosal invasion showed strong association with double-positivity of MUC5AC and MUC6. CONCLUSIONS: Our results indicate that immunohistochemical evaluation is useful for predicting malignant potential of NADETs, especially focusing on the expression of gastrointestinal markers.

Effects of the Helicobacter pylori Virulence Factor CagA and Ammonium Ion on Mucins in AGS Cells.

PURPOSE: To investigate the effects of Helicobacter pylori (H. pylori)-CagA and the urease metabolite NH4⁺ on mucin expression in AGS cells. MATERIALS AND METHODS: AGS cells were transfected with CagA and/or treated with different concentrations of NH4CL. Mucin gene and protein expression was assessed by qPCR and immunofluorescence assays, respectively. RESULTS: CagA significantly upregulated MUC5AC, MUC2, and MUC5B expression in AGS cells, but did not affect E-cadherin and MUC6 expression. MUC5AC, MUC6, and MUC2 expression in AGS cells increased with increasing NH4⁺ concentrations until reaching a peak level at 15 mM. MUC5B mRNA expression in AGS cells (NH4⁺ concentration of 15 mM) was significantly higher than that at 0, 5, and 10 mM NH4⁺. No changes in E-cadherin expression in AGS cells treated with NH4⁺ were noted, except at 20 mM. The expression of MUC5AC, MUC2, and MUC6 mRNA in CagA-transfected AGS cells at an NH4⁺ concentration of 15 mM was significantly higher than that at 0 mM, and decreased at higher concentrations. The expression of MUC5B mRNA increased with increases in NH4⁺ concentration, and was significantly higher compared to that in untreated cells. No significant change in the expression of E-cadherin mRNA in CagA-transfected AGS cells was observed. Immunofluorescence assays confirmed the observed changes. CONCLUSION: H. pylori may affect the expression of MUC5AC, MUC2, MUC5B, and MUC6 in AGS cells via CagA and/or NH4⁺, but not E-cadherin.

Gastric gland mucin-specific O-glycan expression decreases as tumor cells progress from lobular endocervical gland hyperplasia to cervical mucinous carcinoma, gastric type.

Gastric gland mucin-specific O-glycans are unique in having α1,4-linked N-acetylglucosamine (αGlcNAc) attached to MUC6. We previously reported decreased expression of αGlcNAc relative to MUC6 in gastric and pancreatic neoplasms, but its significance in cervical glandular lesions remained unclear. Here, we analyzed MUC5AC, MUC6, αGlcNAc, and p16 expression in 9 lesions of mucinous carcinoma, gastric type with minimal deviation adenocarcinoma (GAS-MDA), 5 of GAS with nonMDA (GAS-nonMDA), 14 of typical lobular endocervical gland hyperplasia (LEGH), and 5 of atypical LEGH (33 total lesions). All 33 were MUC5AC-positive. Moreover, all 14 typical LEGH, 5 atypical LEGH, 8 of 9 GAS-MDA, and 3 of 5 GAS-nonMDA were MUC6-positive. All 14 typical LEGH, 2 of 5 atypical LEGH, 3 of 9 GAS-MDA, and 1 of 5 GAS-nonMDA were αGlcNAc-positive. The proportion of αGlcNAc-positive atypical LEGH or GAS-MDA or GAS-nonMDA lesions was significantly smaller than that seen in typical LEGH lesions (P < 0.001 and P < 0.01, respectively). Of 33 lesions, 32 were p16-negative. Furthermore, when we evaluated MUC6 and αGlcNAc immunoreactivity semi-quantitatively in all 33 lesions, in typical LEGH and GAS-MDA, the immunohistochemical score for αGlcNAc was significantly lower than that for MUC6 (P < 0.01). We did not observe significantly decreased αGlcNAc expression relative to MUC6 in typical LEGH lesions. These studies suggest that αGlcNAc expression decreases as typical LEGH progresses to GAS. Given the difficulty in distinguishing MDA and atypical LEGH from typical LEGH in H.E. staining, we propose that immunohistochemical analysis of αGlcNAc and MUC6 could be useful.

Immunohistochemical expression profiles of mucin antigens in salivary gland mucoepidermoid carcinoma: MUC4- and MUC6-negative expression predicts a shortened survival in the early postoperative phase.

In mucoepidermoid carcinoma (MEC), the most common salivary gland carcinoma, there is a lack of novel prognostic markers, but post-operative early recurrence strongly affects the clinical course and a poor outcome. It is critical to predict which MEC patients are prone to develop recurrence/metastases. Mucins play pivotal roles in influencing cancer biology, thus affecting cell differentiation, adhesion, carcinoma invasion, aggressiveness and/or metastatic potential. Our aim is to elucidate the significance of expression profiles for mucins, particularly MUC4 and MUC6, and their correlations with various clinicopathological features and recurrence in salivary gland MECs. We performed immunohistochemical analyses on patients with surgically resected primary MEC using antibodies against mucin core proteins MUC4/8G7 and MUC6/CLH5 in 73 paraffin-embedded samples. Recurrence was noted in 15 of 73 (20.5%) patients. MUC4 or MUC6 expression was considered to be negative when <30% or 0% of the MEC cells showed positive staining, respectively. MUC4- and/or MUC6-negative expression respectively and variably showed a significant relationship to pathological tumor high-grade, the presence of lymphovascular invasion, lymph node metastasis and/or tumor-related death. In addition, MUC4 showed significantly negative co-expression with MUC6. Kaplan-Meier analyses revealed that not only single MUC4/6-negative expression but also the combination of both predicted significantly shorter disease-free and disease-specific survivals in MECs, especially within the first two years postoperatively. Therefore, each mucin plays a pivotal role in the pathogenesis of MEC progression. The detection of MUC4 and/or MUC6 might be a powerful parameter in the clinical management of MECs in the early postsurgical phase.

Loss of Trefoil Factor 2 From Pancreatic Duct Glands Promotes Formation of Intraductal Papillary Mucinous Neoplasms in Mice.

BACKGROUND & AIMS: Little is known about the origin of pancreatic intraductal papillary mucinous neoplasms (IPMN). Pancreatic duct glands (PDGs) are gland-like outpouches budding off the main pancreatic ducts that function as a progenitor niche for the ductal epithelium; they express gastric mucins and have characteristics of side-branch IPMNs. We investigated whether PDGs are a precursor compartment for IPMNs and the role of Trefoil factor family 2 (TFF2)-a protein expressed by PDGs and the gastric mucosa that are involved in epithelial repair and tumor suppression. METHODS: We obtained pancreatectomy specimens from 20 patients with chronic pancreatitis, 13 with low-grade side-branch IPMNs, and 15 patients with PDAC; histologically normal pancreata were used as controls (n = 18). Samples were analyzed by immunohistochemistry to detect TFF1 and TFF2 and cell proliferation. We performed mitochondrial DNA mutational mapping studies to determine the cell lineage and fate of PDG cells. Pdx1-Cre;LSL-KRASG12D (KC) mice were bred with TFF2-knockout mice to generate KC/Tff2-/- and KC/Tff2+/- mice. Pancreata were collected and histologically analyzed for formation of IPMN, pancreatic intraepithelial neoplasias, and PDAC, in addition to proliferation and protein expression. Human pancreatic ductal epithelial cells and PDAC cell lines were transfected with vectors to overexpress or knock down TFF2 or SMAD4. RESULTS: Histologic analysis of human samples revealed gastric-type IPMN to comprise 2 molecularly distinct layers: a basal crypt segment that expressed TFF2 and overlying papillary projections. Proliferation occurred predominantly in the PDG-containing basal segments. Mitochondrial mutation mapping revealed a 97% match between the profiles of proliferating PDG cells and their overlying nonproliferative IPMN cells. In contrast to KC mice, 2-month-old KC/Tff2+/- and KC/Tff2-/- mice developed prominent papillary structures in the duct epithelium with cystic metaplasia of the PDG, which resembled human IPMN; these expressed gastric mucins (MUC5AC and MUC6), but not the intestinal mucin MUC2. KC/TFF2-knockout mice developed a greater number and higher grade of pancreatic intraepithelial neoplasias than KC mice, and 1 mouse developed an invasive adenocarcinoma. Expression of TFF2 reduced proliferation of PDAC cells 3-fold; this effect required up-regulation and activation of SMAD4. We found expression of TFF2 to be down-regulated in human PDAC by hypermethylation of its promoter. CONCLUSIONS: In histologic analyses of human IPMNs, we found PDGs to form the basal segment and possibly serve as a progenitor compartment. TFF2 has tumor-suppressor activity in the mouse pancreas and prevents formation of mucinous neoplasms.

Helicobacter pylori and gastric mucin expression: A systematic review and meta-analysis.

AIM: To investigate the relationship between Helicobacter pylori (H. pylori) and mucin expression in gastric mucosa. METHODS: English Medical literature searches were conducted for gastric mucin expression in H. pylori infected people vs uninfected people. Searches were performed up to December 31(th) 2014, using MEDLINE, PubMed, EMBASE, Scopus, and CENTRAL. Studies comparing mucin expression in the gastric mucosa in patients positive and negative for H. pylori infection, were included. Meta-analysis was performed by using Comprehensive meta-analysis software (Version 3, Biostat Inc., Englewood, NJ, United States). Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated compared mucin expression in individual studies by using the random effects model. Heterogeneity between studies was evaluated using the Cochran Q-test, and it was considered to be present if the Q-test P value was less than 0.10. I(2) statistic was used to measure the proportion of inconsistency in individual studies, with I(2) > 50% representing substantial heterogeneity. We also calculated a potential publication bias. RESULTS: Eleven studies, which represent 53 sub-studies of 15 different kinds of mucin expression, were selected according to the inclusion criteria. Every kind of mucin has been considered as one study. When a specific mucin has been studied in more than one paper, we combined the results in a nested meta-analysis of this particular mucin: MUC2, MUC6, STn, Paradoxical con A, Tn, T, Type 1 chain mucin, LeA, SLeA, LeB, AB-PAS, MUC1, and MUC5AC. The odds ratio of mucin expression in random analysis was 2.33, 95%CI: 1.230-4.411, P = 0.009, higher expression in H. pylori infected patients. Odds ratio for mucin expression in H. pylori positive patients was higher for MUC6 (9.244, 95%CI: 1.567-54.515, P = 0.014), and significantly lower for MUC5AC (0.447, 95%CI: 0.211-0.949, P = 0.036). Thus, H. pylori infection may increase MUC6 expression and decrease MUC5AC expression by 924% and 52%, respectively. CONCLUSION: H. pylori inhibits MUC5AC expression in the gastric epithelium, and facilitates colonization. In contrast, increased MUC6 expression may help inhibiting colonization, using MUC6 antibiotics properties.

Oxyntic gland adenoma endoscopically mimicking a gastric neuroendocrine tumor: A case report.

Gastric adenocarcinoma is one of the most common malignancies worldwide. Histochemical and immunohistologic analyses classify the phenotypes of gastric adenocarcinoma into several groups based on the variable clinical and pathologic features. A new and rare variant of gastric adenocarcinoma with chief cell differentiation (GA-CCD) has recently been recognized. Studies reporting the distinct clinicopathologic characteristics proposed the term oxyntic gland polyp/adenoma because of the benign nature of the GA-CCD. Typically, GA-CCD is a solitary mucosal lesion that develops either in the gastric cardia or fundus. Histologically, this lesion is characterized by tightly clustered glands and anastomosing cords of chief cells. Immunohistochemically, GA-CCD is diffusely positive for mucin (MUC) 6 and negative for MUC2 and MUC5AC. However, other gastric tumors such as a gastric neuroendocrine tumor or fundic gland polyp have been difficult to exclude. Because GA-CCD tends to be endoscopically misdiagnosed as a neuroendocrine tumor or fundic gland polyp, comprehensive assessment and observation by an endoscopist are strongly recommended. Herein, we report a rare case of oxyntic gland adenoma endoscopically mimicking a gastric neuroendocrine tumor that was successfully removed by endoscopic mucosal resection.

Mucinous phenotype and CD10 expression of primary adenocarcinoma of the small intestine.

AIM: To clarify the correlation with phenotypic expression, clinicopathological features, genetic alteration and microsatellite-instability status in small intestinal adenocarcinoma (SIA). METHODS: The cases of 47 patients diagnosed with primary SIAs that were surgically resected at our institution in 1975-2005 were studied. We reviewed clinicopathological findings (age, gender, tumor size, gross appearance, histological morphologic type, invasion depth, lymphatic permeation, venous invasion, and lymph node metastasis), and the immunohistochemical expression of MUC5AC, MUC6, MUC2, CD10, and mismatch-repair (MMR) proteins (MLH1 and MSH2). We analyzed KRAS and BRAF gene mutations, and the microsatellite instability (MSI) status. The immunohistochemical staining of CD10, MUC2, MUC5AC and MUC6 was considered positive when distinct staining in > 5% of the adenocarcinoma cells was recorded. To evaluate of MMR protein expression, we used adjacent normal tissue including lymphoid follicles, inflammatory cells, and stromal cells as an internal positive control. Sections without nuclear staining in the tumor cells were considered to have lost the expression of the respective MMR protein. RESULTS: There were 29 males and 18 females patients (mean age 59.9 years, range: 23-87 years). Tumors were located in the duodenum in 14 cases (30%), the jejunum in 21 cases (45%), and the ileum in 12 cases (25%). A phenotypic expression analysis revealed 20 MUC2-positive tumors (42.6%), 11 MUC5AC-positive (23.4%), 4 MUC6-positive (8.5%), and 7 CD10-positive (14.9%). The tumor sizes of the MUC2(+) tumors were significantly larger than those of the MUC2(-) tumors (mean, 5.7 ± 1.4 cm vs 4.7 ± 2.1 cm, P < 0.05). All three tumors with adenomatous component were positive for MUC2 (P < 0.05). Polypoid appearance was seen significantly more frequently in the CD10(+) group than in the CD10(-) group (P < 0.05). The tumor size was significantly larger in the CD10 (+) group than in the CD10(-) group (mean, 5.9 ± 1.4 cm vs 5.0 ± 2.1 cm, P < 0.05). Of 34 SIAs with successfully obtained MSI data, 4 were MSI-high. Of the 4 SIAs positive for both MUC5AC and MUC2, 3 showed MSI-H (75%) and 3 were mucinous adenocarcinoma (75%). KRAS mutations were detected in 4 SIAs. SIAs had KRAS mutation expressed only MUC2, but were negative for MUC5AC, MUC6 and CD10. CONCLUSION: These findings suggest that the phenotypic expression of SIAs is correlated with their biological behavior, genetic alteration, and MSI status.

Clinicopathological significance of mucin production in patients with papillary cholangiocarcinoma.

BACKGROUND: The clinicopathologic significance of mucin production in patients with papillary cholangiocarcinoma (PCC) is still controversial. We aimed at clarifying the similarities and differences between PCC cases with and without mucin secretion with regard to biological behavior and clinical course. METHODS: Among 644 patients with surgically resected cholangiocarcinoma (1998-2011), 184 (28 %) patients were considered to have PCC and were enrolled in the study. Those patients were divided into two groups based on whether their PCC was mucin-producing (PCC-M, n = 89) or not (PCC-NM, n = 95). The presence of mucin secretion was determined by the cut surface of the specimens and by pathologic examination. RESULTS: The clinicopathological features of PCC-M and PCC-NM largely overlapped. No significant between-group differences in malignant potential characteristics, including the depth of invasion, pathological T classification, and regional/periaortic lymph node metastasis, were observed (P = 0.193, 0.181, 0.083, and 0.674, respectively). However, a few clinicopathological differences existed between the two PCC types, i.e., the predominant histological type and epithelial subtype (P < 0.001 and P = 0.016, respectively). Immunohistochemically, MUC2, MUC5AC, MUC6, and HGM were more frequently expressed in PCC-M than PCC-NM (P < 0.002 in all). The disease-specific survival values were not significantly different between the two PCC types (PCC-M; 60 % at 5 year, PCC-NM; 46 %, P = 0.097). CONCLUSION: PCC-M and PCC-NM were similar in morphology and prognosis. Although a few clinicopathological differences exist between them, their overlapping features and identical survival curves appear to justify the lack of a specific treatment modality for either type.

Magnifying endoscopy of gastric epithelial dysplasia based on the morphologic characteristics.

AIM: To investigate the difference in magnifying endoscopic findings of gastric epithelial dysplasias (GEDs) according to the morphologic characteristics. METHODS: This study included 46 GED lesions in 45 patients who underwent magnifying endoscopy using narrow band imaging (ME-NBI) before endoscopic resection. During ME-NBI, the microvascular and microsurface (MS) patterns and the presence of light blue crest (LBC) and white opaque substance were investigated. GEDs were categorized as adenomatous, foveolar, and hybrid types, and their mucin phenotype was evaluated. RESULTS: Of the 46 lesions, 27 (59%) were categorized as adenomatous, 15 (32%) as hybrid, and the remaining 4 (9%) as foveolar. All adenomatous GEDs showed the round pit and/or tubular MS patterns, all foveolar GEDs showed the papillary pattern, and hybrid GEDs showed mixed patterns (P < 0.001). LBC was more frequently observed in adenomatous GEDs than in hybrid or foveolar GEDs (52%, 33%, 0%, respectively), although this difference was not significant (P = 0.127). The papillary MS pattern was associated with MUC5AC and MUC6 expression, and the round pit and/or tubular MS patterns were associated with CD10 expression. CONCLUSION: The MS pattern in ME-NBI findings is useful for predicting the morphologic category and mucin phenotype of GEDs, and ME-NBI findings may guide decisions regarding GED treatment.