Expression of the intestine-specific transcription factors, Cdx1 and Cdx2, correlates shift to an intestinal phenotype in gastric cancer cells

Mucin phenotype of differentiated early gastric cancer: an immunohistochemistry study supporting therapeutic decision making

Introduction: Endoscopic submucosal dissection is widely employed in early gastric cancer (EGC). Foveolar phenotypes should be distinguished from the other differentiated EGC (DEGC) types because of their increased malignant potential. The phenotypic classification could be useful not only for investigating EGC tumorigenesis but also for evaluating the tumor aggressiveness to guide treatment decision making. Methods: On surgical tissue specimens, we studied the mucin phenotype of EGC to distinguish cases with a worse prognosis dictating different therapeutic options or a very close surveillance program. DEGC in our series were classified as mucin foveolar (51%) or mucin intestinal (49%) phenotype. We evaluated correlations among foveolar and intestinal phenotypic markers, tumor patterns, clinicopathologic features and prognostic and therapeutic implications. Immunohistochemistry (IHC) for MUC5AC and CDX2 was performed on 63 EGC patient specimens. MUCA5C was employed as gastric foveolar phenotypic marker and CDX2 as intestinal phenotypic marker. Results: Foveolar DEGC was significantly associated with larger tumor size (p=0.01), high grade (G2-G3) (p=0.001), vessel permeation (p=0.05), lymph node metastasis (p=0.001) and ulceration (p=0.001), whereas intestinal type DEGC was associated with low grade (p=0.001). Conclusion: IHC determination of the mucin phenotype is an easy, inexpensive method that can provide useful, sensitive markers distinguishing the foveolar or intestinal phenotype in DEGC. The precise identification of the foveolar type, featuring a poorer prognosis, should sound a warning bell mandating very close study of the lesion before endoscopic treatment or contraindicating endoscopic resection in favor of the open surgery option.

Green epithelium revealed by narrow-band imaging (NBI): a feature for practical assessment of extent of gastric cancer after H. pylori eradication

Background and study aims Assessment of the extent of gastric cancer detected by endoscopy after successful eradication of H. pylori is often difficult even with narrow-band imaging (NBI)-magnifying endoscopy. Using the latter modality, it has often been noted that the cancerous area has a brownish color surrounded by green epithelium (GE). If the histological origin of this GE could be clarified, it could be of practical use for endoscopic assessment of the extent of cancer.

Materials and methods The endoscopic appearance of gastric cancer after eradication therapy was classified into four types: (A) cancer brownish, surrounding mucosa green; (B) cancer brownish, surrounding mucosa brownish; (C) cancer green, surrounding mucosa brownish; and (D) cancer green, surrounding mucosa green. A histological series of sections taken from tissues in each endoscopic view was stained with HE, and also for CDX2, MUC2, CD10 and MUC5AC. Staining intensity was evaluated by microscopy using a visual analog scale ranging from 0 to 3+: intensities of 0 and 1+ were rated as negative, and those of 2+ and 3+ as positive. Positive or negative immunostaining was examined for each type of endoscopic appearance A – D.

Results Among 42 lesions examined, 16 were type A, 18 type B, 6 type C and 2 type D. MUC2 was positive in the surrounding mucosa in 100 % of type A and D cases, but in only 28 % and 17 % of type B and C cases, respectively.

Conclusions GE observed by NBI-endoscopy corresponds to MUC2-positive mucosa and is thought to be a feature for practical assessment of the extent of cancer.

Prognostic significance of CDX2 immunoexpression in poorly differentiated clusters of colorectal carcinoma

CDX2 is a transcription factor that acts as a tumor suppressor in colorectal cancer (CRC). Its loss triggers metastatic process and tumor progression; however, its prognostic role in patients with CRC is still controversial. Poorly differentiated clusters (PDCs) are aggregates of neoplastic cells which likely have high metastatic potential in CRC. In this study, we analyzed and compared CDX2 expression in PDC (CDX2-PDC) and corresponding main tumor (CDX2 main tumor) in 42 CRCs showing at least 10 PDC (PDC G3). Five of 42 CRCs (12%) were classified as CDX2 main tumor negative (4/5 were also PDC-CDX2 negative); all had tumor recurrence and died of CRC. Twenty nine of 42 cases were CDX2-PDC negative. Among CRC CDX2 main tumor positive, 15 had recurrences and 13 died from CRC; 13 and 11 of them, respectively, were CDX2-PDC negative. By assigning one point to CDX2 main tumor or CDX2-PDC positivity, we assessed CDX2-staining score for each case. Twelve cases had CDX2-staining score 2 (CDX2 positive in main tumor and PDC); 26 had score 1 (CDX2 positive in main tumor or PDC), and 4 had CDX2 score 0 (CDX2 negative in main tumor and PDC). In our patients, CDX2-staining score had higher prognostic value compared to CDX2 main tumor or CDX2-PDC alone. In addition, it represented a significant and independent prognostic variable for disease-free survival (DFS) and cancer-specific survival (CSS). Our findings suggest that, although loss of CDX2 in the main tumor identifies high-risk patients with high specificity, CDX2-PDC should also be considered in CDX2 main tumor positive cases to predict prognosis.

Re-evaluation of Phenotypic Expression in Differentiated-type Early Adenocarcinoma of the Stomach

A total of 313 cases of differentiated-type early gastric adenocarcinomas, including 113 cases of small-sized carcinoma (5< × ≤10 mm) and 121 cases of microcarcinoma (0< × ≤5 mm), were examined immunohistochemically to clarify the phenotypic expressions. They were classified into four categories (gastric phenotype (G-type), intestinal phenotype, gastrointestinal phenotype, and null phenotype) by a two-step process: the phenotype based on an immunoprofile of mucin core proteins (MUCs) with CDX2 (w/.CDX2-assessment); and the phenotype of MUCs only (w/o.CDX2-assessment). CDX2 expression was observed in 89.1% (279/313); it was highly expressed in 87.6% (106/121) of microcarcinomas. MUC2 expression increased as tumor size increased (P < 0.05). Compared with w/o.CDX2-assessment, w/.CDX2-assessment showed significantly fewer G-type carcinomas (P < 0.05). Each phenotype marker was less expressed in the submucosal part than in the mucosal part. In conclusion, CDX2 was a sensitive marker for assessing intestinal phenotype. A large portion of the early differentiated-type adenocarcinomas expressed CDX2 from the very early stage of carcinogenesis, and the proportion of G-type was unexpectedly low. Lower expression of each phenotype marker was considered the cause of phenotype alteration during submucosal invasion.

CDX2 protein expression compared to alcian blue staining in the evaluation of esophageal intestinal metaplasia

AIM: To compare the sensitivity and specificity of CDX2 and alcian blue (AB) pH 2.5 staining in identifying esophageal intestinal metaplasia.

METHODS: One hundred and ninty-nine biopsies from 186 patients were retrospectively reviewed and categorized as Barrett’s esophagus (BE) (n = 108); non-Barrett’s esophagus (NBE) (n = 48); columnar blue cells (CB) and esophageal glands (EG) (n = 43). The biopsies were stained with AB and immunostained for CDX2 using a mouse monoclonal antibody from Biogenex (clone CDX2-88) and the Ventana Discovery X automated immunostainer. The positive and negative predictive value of each group was used to determine the predictive power of CDX2 and AB in diagnosing intestinal metaplasia.

RESULTS: All of the 108 BE biopsies (100%) were positive for AB and 102 of them (94.4%) were positive for CDX2. The six BE patients (5.6%) who failed to stain with CDX2 were found to have lost the focus of intestinal metaplasia upon deeper sectioning for immunostaining. Both AB and CDX2 were negative in 43 out of 48 (89.6%) NBE cases. Five NBE patients (10.4%) were falsely positive for AB due to the presence of EG and CB in these biopsies. These cases were all CDX2 negative. In addition, 5 AB negative NBE were found to be CDX2 positive. Based on these results the CDX2 immunostain had similar sensitivity but higher specificity (100% vs about 91%) than AB in detecting intestinal type metaplasia in these samples. Our data shows that CDX2 has a better PPV in detecting intestinal metaplasia as compared to AB (95.6% vs 71.5%, respectively).

CONCLUSION: CDX2 has a better positive predictive value than AB in detecting intestinal metaplasia. CDX2 may be useful when challenged by gastro-esophageal biopsies containing mimikers of BE.

Interaction of sonic hedgehog (SHH) pathway with cancer stem cell genes in gastric cancer

Gastric cancer may appear by frequent genetic or epigenetic changes in oncogenes, tumor suppressor or DNA mismatch repair genes. Molecular studies show the possibility of involvement of certain cancer pathways in gastric cancer. In this respect, DNA methylation is one of the most important epigenetic alterations in gastric cancer and identifying the signaling mechanism and also methylation of some genes that are involved in gastric cancer can help to improve treatment strategies. Relatively, there are many reported methylation alteration of genes in stem cells in all kinds of tumors with some of these genes having a key role in tumor development. Correspondingly, KLF5, CDX1/2, WNT1 and FEM1A are considerable genes in gastric cancer, although many researches and studies have illustrated that sonic hedgehog and expression of its signaling cascade proteins are related in gastric cancer. Relatively, modification in these genes causes many eclectic cancers such as rhabdomyosarcoma and diverse kinds of digestive system tumor development. Conspicuously, these master genes have a noticeable role in stem cell's growth regulation as well as other kinds of cancer such as breast cancer and leukemia. Hence, we concluded that research and studies on methylation and expression of these genes and also the investigation of molecular signaling in gastric cancer can acquire impressive conclusions in order to control and treat this common place and serious problem.

Extra-ampullary duodenal adenocarcinoma

Extra-ampullary duodenal adenocarcinomas are rare, and when studied, frequently have been grouped with jejunoileal adenocarcinomas. Nevertheless, anecdotal experiences suggest that these neoplasms may present 2 or more distinct phenotypes. To better characterize these neoplasms, we performed a retrospective review of 38 cases with a special focus on the morphologic and immunophenotypic characteristics and their clinicopathologic significance. Our cohort of extra-ampullary duodenal adenocarcinomas was classified on the basis of the morphologic features into gastric type (n=19, 50%), intestinal type (n=14, 37%), pancreaticobiliary type (n=2, 5%), and others (n=3, 8%). Most gastric-type adenocarcinomas (n=18, 95%) developed in the proximal duodenum, whereas the other types were located equally in the proximal and distal duodenum. Intestinal-type dysplasia was present at the periphery of 8 (57%) intestinal-type adenocarcinomas, and 8 (42%) gastric-type adenocarcinoma were associated with gastric-type dysplasia. Gastric foveolar metaplasia (n=12) and Brunner gland hyperplasia (n=10) were exclusively recognized adjacent to gastric-type adenocarcinomas. Notably, intestinal-type histology and the absence of lymph node metastasis were significantly associated with favorable disease-free survival in univariate and multivariate analyses. In summary, this study demonstrated that 2 major subsets of extra-ampullary duodenal adenocarcinoma, intestinal type and gastric type, are associated with distinct histopathologic features and clinical behavior.

Re-evaluation of phenotypic expression in undifferentiated-type early gastric adenocarcinomas using mucin core protein and CDX2

BACKGROUND

Undifferentiated-type early gastric adenocarcinomas are generally classified into two groups: pure undifferentiated-type adenocarcinomas, which naturally develop as undifferentiated-type without a glandular component; and mixed differentiated/undifferentiated-type adenocarcinomas, which are associated with some vestigial glandular component and presumably develop from differentiated-type adenocarcinoma. The differences in phenotypic expression between these two groups were examined using mucin core protein and CDX2.

METHODS

A total of 210 lesions of undifferentiated-type early gastric adenocarcinoma less than 25 mm in diameter were classified into four categories (gastric type, gastrointestinal type, intestinal type, and null type) based on their MUC5AC, MUC6, MUC2, and CDX2 immunoprofiles.

RESULTS

Gastric type was significantly (p < 0.01) decreased and gastrointestinal type was significantly (p < 0.01) increased both in pure undifferentiated-type adenocarcinomas and in mixed differentiated/undifferentiated-type adenocarcinomas when CDX2 was applied to mucin core protein. In the pure undifferentiated-type adenocarcinomas, gastric type decreased and gastrointestinal type increased as tumor size increased (p < 0.05). In contrast, in the mixed differentiated/undifferentiated-type adenocarcinomas, gastrointestinal type was most common even in small-sized (≤10 mm) carcinomas and was generally stable regardless of tumor size. In submucosal carcinomas, gastrointestinal type decreased and gastric type and intestinal type increased during carcinoma invasion from the intramucosal to submucosal parts (p < 0.05). The positivity rates for all phenotypic markers, especially gastric markers, tended to decrease during submucosal invasion.

CONCLUSIONS

CDX2 is a sensitive marker for assessing intestinal phenotypic expression, and it is likely that there are two different pathways of tumor progression in undifferentiated-type adenocarcinoma of the stomach, according to phenotypic expression.

Helicobacter pylori infection and gastric carcinogenesis in rodent models

Helicobacter pylori infection is an important factor for gastric carcinogenesis in human. In carcinogen-treated Mongolian gerbils, H. pylori infection enhances stomach carcinogenesis, while infection alone induced severe hyperplasia called heterotopic proliferative glands. A high-salt diet or early acquisition of the bacteria exacerbates inflammation and carcinogenesis. Oxygen radical scavengers or anti-inflammatory chemicals as well as eradication of H. pylori are effective to prevent carcinogenesis. H. pylori-associated inflammation induces intestinal metaplasia and intestinalization of stomach cancers independently. It is necessary to control cancer development not only in H. pylori-positive cases but also in H. pylori-negative metaplastic gastritis.

A Tale of Two Toxins: Helicobacter Pylori CagA and VacA Modulate Host Pathways that Impact Disease

Helicobacter pylori is a pathogenic bacterium that colonizes more than 50% of the world's population, which leads to a tremendous medical burden. H. pylori infection is associated with such varied diseases as gastritis, peptic ulcers, and two forms of gastric cancer: gastric adenocarcinoma and mucosa-associated lymphoid tissue lymphoma. This association represents a novel paradigm for cancer development; H. pylori is currently the only bacterium to be recognized as a carcinogen. Therefore, a significant amount of research has been conducted to identify the bacterial factors and the deregulated host cell pathways that are responsible for the progression to more severe disease states. Two of the virulence factors that have been implicated in this process are cytotoxin-associated gene A (CagA) and vacuolating cytotoxin A (VacA), which are cytotoxins that are injected and secreted by H. pylori, respectively. Both of these virulence factors are polymorphic and affect a multitude of host cellular pathways. These combined facts could easily contribute to differences in disease severity across the population as various CagA and VacA alleles differentially target some pathways. Herein we highlight the diverse types of cellular pathways and processes targeted by these important toxins.

Sonic hedgehog and CDX2 expression in the stomach

Sonic hedgehog (Shh) is an essential regulator of patterning processes throughout development, and CDX proteins act as the master regulators for intestinal development and differentiation. Shh and CDX2 seem to be interdependently linked with cellular differentiation through different signal cascades. We have recently shown that the loss of Shh and aberrant expression of CDX2 in Helicobacter pylori (H. pylori)-associated atrophic gastritis can be modified by H. pylori eradication prior to incomplete intestinal metaplasia. On the other hand, abnormal signaling of the hedgehog pathway has been reported in gastric cancer, especially diffuse-type cancer and advanced gastric cancer, and Shh acts as a proliferation factor in both the normal mucosa and malignant lesions. CDX2 expressed in the early stage of gastric carcinogenesis is associated with the intestinal phenotypic region and thus with a better outcome. However, it remains unclear how Shh and CDX2 are involved with intestinal transformation and further carcinogenesis.

Helicobacter pylori infection induces a reversible expression of the CDX2 transcription factor protein in human gastric epithelium

OBJECTIVE

The homeobox gene CDX2 is implicated in the appearance of intestinal metaplasia in Helicobacter pylori gastritis. The aim of this study was to investigate whether CDX2 expression in gastric mucosa occurs before the appearance of overt intestinal metaplasia in H. pylori gastritis, and whether or not this expression is reversible.

MATERIAL AND METHODS

CDX2 was studied by immunohistochemistry in a cohort of 38 patients with H. pylori gastritis before and after eradication (mean follow-up 6.3 years) of H. pylori. A cohort of 49 individuals with healthy stomachs was analysed as a control.

RESULTS

In the control group no immunostaining of CDX2 in the epithelial cells of the gastric body was found, while in 57% of the cases a mild, aberrant nuclear immunostaining of CDX2 in the non-metaplastic epithelial cells in antrum, designated as "positive staining of single cells" (PSSC), was found. In H. pylori gastritis, the PSSC was seen in antrum and corpus in 100% and 26% of the cases, respectively. The prevalence of antral PSSC was significantly increased (on average by 4-fold) in H. pylori gastritis as compared with controls. After eradication of H. pylori, the prevalence of PSSC decreased significantly in antrum but not in corpus.

CONCLUSIONS

Expression of CDX2 at low intensity is common in the epithelium of normal antrum, and this expression is enhanced in H. pylori gastritis. Expression of CDX2 is reversible at least in antrum after eradication of H. pylori infection.

Adenomatous and foveolar gastric dysplasia: distinct patterns of mucin expression and background intestinal metaplasia

Gastric epithelial dysplasia (GED) can be morphologically categorized into adenomatous (or intestinal) and foveolar (or gastric) types. Although limited genetic differences have been demonstrated between these subtypes, the expression of various mucins has not been systematically evaluated in this context. Endoscopic mucosal resections from 69 cases of GEDs were evaluated for the expression of MUC2, MUC5AC, MUC6, and CD10. The results were correlated with morphologic categorization and clinicopathologic parameters. GED was classified as adenomatous, foveolar, or hybrid (showing features of both types), on the basis of histologic evaluation. The neighboring intestinal metaplasia (IM) was also evaluated. An adenomatous morphology was seen in 45%, hybrid type in 33.3%, and a "pure" foveolar type was seen in 21.7% of the cases. Foveolar GED was often depressed/flat on endoscopy and showed a statistically significant association with high-grade morphology (P = 0.046). Immunohistochemistry confirmed the histologic stratification. The foveolar and hybrid types were more often positive for MUC5AC (P = 0.0001 for both) and negative for CD10 (P = 0.019 and 0.016, respectively) as compared with adenomatous GED. High-grade morphology was associated with MUC5AC expression regardless of the morphologic phenotype (P = 0.026). Foveolar (73.3%) and hybrid (86.9%) GEDs were associated more often with IM showing a retained expression of gastric type mucin than adenomatous GED (29%) (P < 0.01 for both). In contrast, adenomatous type (58.1%) of GED was significantly associated with IM showing a complete intestinal phenotype (CD10+) compared with the foveolar (13.3%) and hybrid types (17.4%) of GED (P = 0.005 for both comparisons). In conclusion, our study indicates that foveolar and adenomatous types of GED have distinct clinicopathologic features, mucin profiles, and association with different types of IM.

Animal models of stomach carcinogenesis

Although incidences of stomach cancer have decreased over the past several decades, the disease remains an important public health problem. To identify pathological and molecular biochemical mechanisms, various experimental animal models have been established in rats and mice with chemical carcinogens including N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and N-methyl-N-nitrosourea (MNU). Helicobacter pylori(H. pylori) is one of the most important factors for human stomach disorders, including neoplasia, and the H. pylori-infected and carcinogen-treated Mongolian gerbil (MG) has proven very useful for analyses of underlying processes. The findings with this model support the hypothesis that intestinal metaplasia is important not as a precancerous lesion but rather as a paracancerous condition and that intestinalization of stomach cancer progresses with chronic inflammation. Furthermore, dose-dependent enhancing effects of salt on stomach carcinogenesis could be demonstrated in MGs treated with MNU and H. pylori modifying surface mucous gel layer. H. pylori itself only causes chronic inflammation and acts as a promoter of stomach carcinogenesis in experimental models. Based on the precise pathological diagnosis of stomach lesions such as noncancerous heterotopic proliferative glands (HPG) and adenocarcinomas, a basis for understanding mechanisms of carcinogenesis has been established on which chemoprevention can be modeled.

Gastric adenocarcinoma with chief cell differentiation

A case of adenocarcinoma with chief cell differentiation, a novel entity in the stomach, is presented. An 82-year-old woman who had undergone distal gastrectomy, was scheduled for upper gastrointestinal endoscopy to clarify mechanical ileus. A protruding tumor 16 x 14 x 9 mm in size was found in the cardia of the remnant stomach. Histological examination indicated a well-differentiated tubular adenocarcinoma composed of basophilic columnar or cuboidal cells with occasional coarse eosinophilic granules. Immunohistochemical analysis revealed strong expression of pepsinogens I and II and Runt-related transcription factor gene 3 (RUNX3), characteristic for chief cells, and MUC6 typical for mucous neck cells. However, the tumor cells were negative for the proton pump alpha subunit, a marker for parietal cells. Cdx2 and defensin-5 were not present, confirming the lack of an intestinal phenotype. The cancer cells shared characteristics of a chief cell and a mucous neck cell, resembling an ancestor of these two cell types, so-called 'primitive chief cell' in fundic gland. In line with these data, the cancer was diagnosed as an adenocarcinoma with chief cell differentiation.

Phenotypic classification of gastric signet ring cell carcinoma and its relationship with clinicopathologic parameters and prognosis

AIM: To distinguish subtypes of gastric signet ring cell (SRC) carcinoma by investigating the expression of gastric and intestinal phenotypic markers, and to study the significance of phenotypic classification in predicting tumor progression and outcome.

METHODS: Immunohistochemistry was performed in 66 cases of SRC carcinoma with MUC2, VILLIN, CDX2, Li-cadherin antibodies as intestinal phenotype markers and MUC5AC, HGM, MUC6 antibodies as gastric phenotype markers, and the relationship was analyzed between the phenotypic expression pattern and clinicopathologic parameters, as well as the 3-year survival rate.

RESULTS: Expression of intestinal phenotypic markers was positively associated with tumor size, wall invasion, vascular invasion, lymph node metastasis and tumor-node-metastasis (TNM) stage. Cases expressing one or more intestinal markers had a significant lower survival rate than cases expressing none of the intestinal markers.

CONCLUSION: The SRC carcinomas expressing intestinal phenotype markers exhibited a high pro-liferative potential, bad biological behaviors and poor prognosis. Examination of phenotype expression may be useful in distinguishing histological type and in predicting the prognosis of gastric SRC carcinoma.

Precancerous lesions upon sporadic activation of beta-catenin in mice

BACKGROUND & AIMS

Inappropriate activation of beta-catenin in adult tissues is associated with a wide variety of cancers, especially in the digestive tract. Classic transgenic and knockout murine models in which beta-catenin is activated in large fields of cells have provided experimental support in favor of a role for this molecule in tumorigenesis. However, these models do not reproduce the sporadic nature of the majority of human cancers, beginning with the activation of an oncogene at random in a single cell.

METHODS

We used the "hit and run" strategy to generate a mouse model in which the expression of an activated form of beta-catenin occurs sporadically in vivo.

RESULTS

Sporadic, multifocal lesions were observed in the stomach of 3% of mice aged 8 months and older. These lesions were associated with loss of Sonic hedgehog (Shh), and a causal relationship between beta-catenin activation and Shh inhibition was established in gastric cells in vitro. No lesion was detected in the intestine or in the liver. In addition, one third of female mutant mice developed benign perimammary papillomas. Mutant mice were also hypersensitive to chemically induced premalignant skin lesions.

CONCLUSIONS

These results challenge the view that activation of beta-catenin induces malignant cancerogenesis, because they show in mice that sporadically activated beta-catenin is sufficient for tumor initiation, yet without further malignant progression, and that it sensitizes cells to environmental hits. This model represents a powerful tool to investigate the interplay between genetic and environmental factors in tumor progression.

Helicobacter pylori CagA interacts with E-cadherin and deregulates the beta-catenin signal that promotes intestinal transdifferentiation in gastric epithelial cells

Infection with Helicobacter pylori cagA-positive strains is associated with gastric adenocarcinoma. Intestinal metaplasia is a precancerous lesion of the stomach characterized by transdifferentiation of the gastric mucosa to an intestinal phenotype. The H. pylori cagA gene product, CagA, is delivered into gastric epithelial cells, where it undergoes tyrosine phosphorylation by Src family kinases. Tyrosine-phosphorylated CagA specifically binds to and activates SHP-2 phosphatase, thereby inducing cell-morphological transformation. We report here that CagA physically interacts with E-cadherin independently of CagA tyrosine phosphorylation. The CagA/E-cadherin interaction impairs the complex formation between E-cadherin and beta-catenin, causing cytoplasmic and nuclear accumulation of beta-catenin. CagA-deregulated beta-catenin then transactivates beta-catenin-dependent genes such as cdx1, which encodes intestinal specific CDX1 transcription factor. In addition to beta-catenin signal, CagA also transactivates p21(WAF1/Cip1), again, in a phosphorylation-independent manner. Consequently, CagA induces aberrant expression of an intestinal-differentiation marker, goblet-cell mucin MUC2, in gastric epithelial cells that have been arrested in G1 by p21(WAF1/Cip1). These results indicate that perturbation of the E-cadherin/beta-catenin complex by H. pylori CagA plays an important role in the development of intestinal metaplasia, a premalignant transdifferentiation of gastric epithelial cells from which intestinal-type gastric adenocarcinoma arises.

Transcription factor SOX2 up-regulates stomach-specific pepsinogen A gene expression

PURPOSE

Transcription factor SOX2 is expressed in normal gastric mucosae but not in the normal colon. We aimed to clarify the role of SOX2 with reference to pepsinogen expression in the gastrointestinal epithelium.

METHODS

We analyzed expression of SOX2 and pepsinogens, differentiation markers of the stomach, in ten gastric cancer (GC) and ten colorectal cancer (CRC) cell lines. The effects of over-expression and down-regulation of SOX2 on pepsinogen expression were also examined.

RESULTS

Six GC and five CRC cell lines showed SOX2 expression on RT-PCR. Expression of pepsinogen A was detectable in eight GC and seven CRC cell lines, whereas the majority of the cell lines expressed pepsinogen C. Over-expression of SOX2 up-regulated expression of pepsinogen A but not that of pepsinogen C in 293T human embryonic kidney cells, and some GC and CRC cell lines. Moreover, pepsinogen A expression was significantly reduced by SOX2 RNA interference in two GC cell lines.

CONCLUSION

These data suggest that SOX2 plays an important role in regulation of pepsinogen A, and ectopic expression of SOX2 may be associated with abnormal differentiation of colorectal cancer cells.

High level of expression of alpha-fetoprotein receptor in gastric cancers

The expression of the receptor for alpha-fetoprotein (AFP-R) was examined immunohistochemically in 47 cancer and 14 benign human gastric tissues. Rabbit polyclonal antibody against human AFP-R was used for immunohistochemical staining. Thirty-four of the 47 cancer tissues expressed AFP-R showing granular or reticular staining on the cancer cell surface, while only 2 of 61 control cases (14 benign gastric tissues and 47 nonmalignant tissues adjacent to cancer) showed faint and homogeneous staining in the cytoplasm of noncancerous cells. There was a significant difference in staining intensity between the cancerous and noncancerous groups. However, no statistically significant difference in staining intensity was found among the groups of well-differentiated, moderately differentiated and poorly differentiated adenocarcinomas. On the other hand, the staining intensity of signet ring cell carcinoma was significantly weaker than that of the three adenocarcinoma groups. The high level of AFP-R expression in gastric cancers may allow the use of AFP-R as a new clinically useful marker of gastric cancer in the tissue level.

CDX2 expression is increased in gastric cancers with less invasiveness and intestinal mucin phenotype

OBJECTIVE

CDX2 is an intestinal transcription factor that might be involved in the regulation of proliferation and differentiation of intestinal epithelial cells. It is well known that both gastric and intestinal phenotypic cell markers are expressed in gastric cancers. The aims of this study were to analyze the CDX2 expression and its relationship with the patients' clinicopathological characteristics and the mucin phenotypes by performing immunohistochemistry.

MATERIAL AND METHODS

A total of 259 gastric cancer cases (122 early and 137 advanced cancers) were evaluated histologically and phenotypically. CDX2 expression was assessed by immunohistochemistry.

RESULTS

Increased CDX2 expression correlated with a higher proportion of intestinal-type cancers of Lauren and early gastric cancers (p<0.001 and p<0.001, respectively) and a lower proportion of perineural invasion and lymph node metastasis (p<0.001 and p=0.003, respectively). Increased expressions of intestinal mucin (MUC-2, CD10) and decreased gastric mucin (MUC5AC) were associated with an increased CDX2 expression (p<0.001, p=0.045 and p=0.004, respectively). MUC6 expression was not associated with CDX2 expression. There was a significantly increased CDX2 expression in the intestinal phenotype compared with the other phenotypes (p<0.001).

CONCLUSIONS

These results suggest that CDX2 might be a useful marker in predicting the clinical outcome for patients with gastric cancers.

CDX2 does not suppress tumorigenicity in the human gastric cancer cell line MKN45

CDX2 is a Drosophila caudal-related homeobox transcription factor that is expressed specifically in the intestine. In mice, ectopic expression of CDX2 in the gastric mucosa gives rise to intestinal metaplasia and in one model, gastric carcinoma. In humans, increased CDX2 expression is associated with gastric intestinal metaplasia and tubular adenocarcinomas. These patterns of expression have shown that CDX2 is important for the initiation of intestinal metaplasia in the gastric mucosa, but the role of CDX2 in established gastric cancer remains unclear. We sought to determine whether CDX2 contributes to tumorigenic potential in established gastric cancer. The CDX2 gene in MKN45 gastric carcinoma cells was disrupted using targeted homologous recombination. The resulting CDX2-/- cells are essentially identical to their parental cells, with the exception of CDX2 ablation. We found no significant differences in the proliferation of CDX2-/- cells compared to CDX2+/+ cells, in vitro or in vivo. Molecular analyses show that loss of CDX2 predominantly altered the expression of genes involved in intestinal glandular differentiation and adhesion. However, there were no microscopic differences in tumor differentiation. We conclude that disruption of CDX2 in MKN45 cells does not significantly affect their tumorigenic potential.

Gastric and intestinal phenotypes and histogenesis of advanced glandular stomach cancers in carcinogen-treated, Helicobacter pylori-infected Mongolian gerbils

The Helicobacter pylori-infected Mongolian gerbil (MG) has been established as an appropriate animal model for studies of stomach cancer development. However, there have hitherto been no data on the phenotypic classification of glandular stomach cancers in H. pylori-infected and non-infected MG. We therefore examined the phenotypes of 50 and six advanced glandular stomach cancers in H. pylori-infected and non-infected MG, respectively, as well as adjacent non-neoplastic mucosa, using several gastrointestinal epithelial phenotypic markers. The lesions were divided phenotypically into 21 gastric, 24 gastric-and-intestinal mixed, four intestinal and one null types, with 90.0% of the lesions harboring gastric elements and 56.0% demonstrating intestinal phenotypic expression in H. pylori-infected MG. All six lesions were classified as gastric type in non-infected MG. There was no clear correlation with the presence of intestinal metaplasia in surrounding mucosa. In conclusion, our data suggest that most advanced adenocarcinomas retain a gastric cellular phenotype in the glandular MG stomach. Thus, it might be proposed that intestinal metaplasia is a paracancerous phenomenon rather than a premalignant condition. H. pylori infection may trigger intestinalization of both stomach cancers and non-neoplastic mucosa.

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.

Establishment and characterization of a human colonic mucinous carcinoma cell line with predominant goblet-cell differentiation from liver metastasis

Many human colorectal adenocarcinoma cell lines have been developed. However, differentiated type colorectal cancer cell lines, particularly, the goblet-cell differentiated type, are scarce. In the present study a novel colorectal adenocarcinoma cell line (designated as COLM-6) with predominant goblet-cell differentiation was established from the rectal mucinous adenocarcinoma of a Japanese woman. COLM-6 cells grow in a typical epithelial monolayer in culture. They expressed epidermal growth factor (EGF) receptor and HER2 on their surface and accordingly, their growth was significantly stimulated by EGF, transforming growth factor (TGF)-alpha and heregulin. COLM-6 cells form tumor with typical mucinous adenocarcinomatous appearance in nude mice. Immunohistochemical analysis of these subcutaneous tumors demonstrated that COLM-6 cells strongly express MUC2 as a goblet-cell marker and Cdx2 in the nucleus. Some weakly express villin and carbonic anhydrase 1 as a columnar absorptive-cell marker as well. They were also positive for adenomatous polyposis coli (APC) cytoplasmically and expressed beta-catenin in their cytoplasm and cell membrane without nuclear accumulation. These results indicate that COLM-6 cell line has unique characteristics and may provide a useful tool to study the mechanism of growth and differentiation of colonic epithelium as well as the biological behavior of colorectal mucinous adenocarcinoma.

Colonic and small-intestinal phenotypes in gastric cancers: Relationships with clinicopathological findings

The clinicopathological significance of colonic and small-intestinal phenotypes has hitherto remained unclear in gastric cancers. The purpose of the present study was therefore to examine 86 gastric carcinomas histologically and phenotypically using several phenotypic markers, including colon-specific carbonic anhydrase 1 (CA1) and sucrase as small-intestine specific marker. Of 86 gastric cancers, sucrase and CA1 expression was observed in 12 (14.0%) and only in two cases (2.3%), respectively, associated with other intestinal markers such as villin and mucin core protein (MUC)2. In the sucrase cases, expression appeared independent of the stage. However, CA1 expression was observed only in two advanced cases. No association was observed between colonic and small-intestinal phenotypes, and lymph node metastasis and postoperative survival in the advanced gastric cancer cases with intestinal phenotypic expression. Cdx2 appeared to be linked to upregulation of both CA1 and sucrase. In conclusion, the data suggest that colonic phenotype occurs rarely in gastric carcinogenesis. Colonic and small-intestinal phenotypes appear with expression of several intestinal phenotypic markers under the control of Cdx2 and presumably other related transcription factors.

Expression of small intestinal and colonic phenotypes in complete intestinal metaplasia of the human stomach

The incomplete intestinal metaplasia (IM) that is reported to be a risk factor for gastric carcinogenesis in man usually features sulfomucin production and thus is considered of colonic type. To cast light on the underlying mechanisms, we here examined the proportions of colonic and small intestinal phenotypes in IM by immunohistochemistry and real-time reverse transcription-polymerase chain reaction at the single isolated gland level. Carbonic anhydrase 1 (CA1) is a specific marker of colonic epithelial cells, whereas sucrase is specific to absorptive cells of the small intestine. Totals of 139 (23.5%) and 452 (76.5%) IM glands were judged to be CA1 positive and CA1 negative, respectively, in resected pyloric mucosa from cancer patients. The average score for MUC5AC in CA1-positive IMs was significantly lower than in CA1-negative counterpart tissue (P<0.0001), whereas the opposite was the case for sucrase (P<0.0001). High iron diamine-Alcian blue staining revealed CA1 expression to coincide with type I complete IM. The expression of CA1 mRNA strongly correlated with that of sucrase-isomaltase, and inversely with that of MUC5AC in isolated IM glands. In conclusion, CA1 could be colocalized with small intestinal proteins such as sucrase, but only rarely with the gastric mucin, MUC5AC. Its expression warrants further study, with the focus on stimulation and/or suppression mechanisms by gastric and intestinal transcription factors.

Sox2 expression in human stomach adenocarcinomas with gastric and gastric-and-intestinal-mixed phenotypes

AIMS

Other than ectopic expression of intestinal transcription factors, Cdx1 and Cdx2, the molecular mechanisms underlying gastric and intestinal phenotypes of human stomach adenocarcinomas have yet to be clarified in detail. We have reported that Sox2, an HMG-box gastric transcription factor, is expressed in normal gastric mucosa and down-regulated in intestinal metaplasia.

METHODS AND RESULTS

We analysed mRNA levels of Sox2 and other differentiation markers in 50 surgically resected stomach adenocarcinomas, immunohistochemically classified into gastric (G), gastric-and-intestinal (GI)-mixed, solely intestinal (I), and null (N) types. Sox2 was found to be transcribed in G and GI-mixed type adenocarcinomas in accordance with MUC5AC and MUC6 expression, while Cdx1 and Cdx2 were up-regulated in GI-mixed and I types along with the expression of MUC2 and villin. In the N type, both gastric and intestinal transcription factors were suppressed. Immunohistochemistry confirmed expression of Sox2 in MUC5AC+ lesions and Cdx2 localization together with MUC2. A stomach adenocarcinoma cell line, KATOIII, demonstrated both MUC5AC and Sox2, although MUC5AC mRNA was not detected in the Sox2+ AGS cell line.

CONCLUSIONS

Sox2 may play an important role in maintaining a gastric phenotype in stomach cancers as well as in normal tissue, in cooperation with other cofactor(s).

Expression of the caudal-type homeodomain transcription factors CDX 1/2 and outcome in carcinomas of the ampulla of Vater

PURPOSE

Adenocarcinomas of the ampulla of Vater demonstrate a characteristic histology but vary significantly in outcome. As a consequence, prognostic factors for these cancers are poorly defined. The caudal-type homeodomain transcription factors 1 (CDX1) and 2 (CDX2) regulate axial development and intestinal differentiation. We assessed the expression of these putative intestinal epithelial-specific transcription factors and their influence on patient outcome.

PATIENTS AND METHODS

Fifty-three resected carcinomas of the ampulla of Vater, 31 pancreatic ductal adenocarcinomas, and 15 extrahepatic biliary carcinomas were analyzed for CDX1 and CDX2 expression using immunohistochemistry.

RESULTS

Forty percent of carcinomas of the ampulla of Vater but less than 5% of pancreatic and biliary adenocarcinomas expressed CDX. Expression of CDX was associated with a better prognosis (P = .0009). Individually, both CDX1 (P = .02) and CDX2 (P = .02) expression were associated with a survival advantage on univariate analysis. Advanced T stage (P = .02), lymph node metastases (P = .004), and vascular space invasion (P = .0009) were associated with a poor prognosis. Multivariate analysis revealed vascular space invasion (P = .01) and CDX expression (P = .01) to be independent prognostic factors.

CONCLUSION

Expression of CDX was an independent marker of outcome in patients with resected adenocarcinoma of the ampulla of Vater. Expression of CDX may distinguish good prognosis intestinal-like tumors, which potentially arise within intestinal epithelium, from poorer prognosis pancreatobiliary tumors, which arise in adjacent pancreatic and/or biliary ductal epithelium.

Role of Helicobacter pylori in gastric carcinogenesis: the origin of gastric cancers and heterotopic proliferative glands in Mongolian gerbils

Helicobacter pylori infection is well accepted to be a very important factor for the development of gastric carcinogenesis in the human stomach. In Mongolian gerbils treated with chemical carcinogens, H. pylori infection enhances glandular stomach carcinogenesis, and eradication of infection and results in curtailment of enhancing effects, particularly at early stages of associated inflammation. A high-salt diet exacerbates the effects of H. pylori infection on gastric carcinogenesis, and these two factors act synergistically to promote the development of gastric cancers in this animal model. However, the bacterium exerts the greater effects. Early acquisition significantly increases gastric chemical carcinogenesis in Mongolian gerbils, as compared to later infection. While heterotopic proliferative glands, hyperplastic and dilated glands localized beneath the muscularis mucosae, frequently develop with H. pylori infection alone in this animal model, they obviously regress on eradication, suggesting a relation to severe gastritis, rather than a malignant character. Furthermore, endocrine cells, positive for chromogranin A, are observed in the heterotopic proliferative glands, in contrast to cancerous lesions which lack endocrine elements. In conclusion, H. pylori is not an initiator, but rather a strong promoter of gastric carcinogenesis, whose eradication, together with reduction in salt intake, might effectively prevent gastric cancer development.

Gene Expression Profiles in Pancreatic Intraepithelial Neoplasia Reflect the Effects of Hedgehog Signaling on Pancreatic Ductal Epithelial Cells

Invasive pancreatic cancer is thought to develop through a series of noninvasive duct lesions known as pancreatic intraepithelial neoplasia (PanIN). We used cDNA microarrays interrogating 15,000 transcripts to identify 49 genes that were differentially expressed in microdissected early PanIN lesions (PanIN-1B/2) compared with microdissected normal duct epithelium. In this analysis, a cluster of extrapancreatic foregut markers, including pepsinogen C, MUC6, KLF4, and TFF1, was found to be up-regulated in PanIN. Up-regulation of these genes was further validated using combinations of real-time reverse transcription-PCR, in situ hybridization, and immunohistochemistry in a total of 150 early PanIN lesions from 81 patients. Identification of these gastrointestinal transcripts in human PanIN prompted assessment of other foregut markers by both semiquantitative and real-time reverse transcription-PCR, revealing similar up-regulation of Sox-2, Gastrin, HoxA5, GATA4/5/6, Villin and Forkhead 6 (Foxl1). In contrast to frequent expression of multiple gastric epithelial markers, the intestinal markers intestinal fatty acid binding protein, CDX1 and CDX2 were rarely expressed either in PanIN lesions or in invasive pancreatic cancer. Hedgehog pathway activation induced by transfection of immortalized human pancreatic ductal epithelial cells with Gli1 resulted in up-regulation of the majority of foregut markers seen in early PanIN lesions. These data show frequent up-regulation of foregut markers in early PanIN lesions and suggest that PanIN development may involve Hedgehog-mediated conversion to a gastric epithelial differentiation program.

Immunohistochemically detectable Cdx2 is present in intestinal phenotypic elements in early gastric cancers of both differentiated and undifferentiated types, with no correlation to non-neoplastic surrounding mucosa

It has previously been reported that Cdx2 is the useful prognostic and intestinal phenotypic marker in advanced gastric cancers (GC). In this study, Cdx2 expression and phenotype in early GC and non-neoplastic surrounding mucosa were examined. A total of 130 early GC (70 intramucosal and 60 submucosally invasive cancers) histologically and phenotypically were evaluated. The expression of Cdx2 was assessed by immunohistochemistry. The lesions were phenotypically divided into 44 gastric (G), 42 gastric and intestinal mixed (GI), 30 intestinal (I), and 14 null (N) types, independent of the histological classification. Most of the early GC were Cdx2-positive, nuclear staining being strongly associated with intestinal phenotypic expression. Early differentiated cancers tended to feature both Cdx2 and intestinal phenotypic expression, while their undifferentiated counterparts were more likely to demonstrate only gastric phenotypic expression (P < 0.05). The phenotypes of six intramucosal microcarcinomas did not correlate with those of adjacent normal glands. These data suggest that Cdx2 is expressed in the very early stage of gastric carcinogenesis in association with the shift from gastric to intestinal phenotypic expression. This appears to occur in differentiated cancers at an earlier stage than in undifferentiated ones, and may be linked to suppression of expansion of malignant cells.

Down-regulation of the homeodomain factor Cdx2 in colorectal cancer by collagen type I: an active role for the tumor environment in malignant tumor progression

The homeobox transcription factor Cdx2 specifies intestinal development and homeostasis and is considered a tumor suppressor in colorectal carcinogenesis. However, Cdx2 mutations are rarely found. Invasion of colorectal cancer is characterized by a transient loss of differentiation and nuclear accumulation of the oncoprotein beta-catenin in budding tumor cells. Strikingly, this is reversed in growing metastases, indicating that tumor progression is a dynamic process that is not only driven by genetic alterations but also regulated by the tumor environment. Here we describe a transient loss of Cdx2 in budding tumor cells at the tumor host interface, and reexpression of Cdx2 in metastases. Cell culture experiments show that collagen type I, through beta(1) integrin signaling, triggers a transient transcriptional down-regulation of Cdx2 and its intestine-specific target gene sucrase isomaltase, associated with a loss of differentiation. These data indicate an active role for the tumor environment in malignant tumor progression.

Expression of the intestinal marker Cdx2 in the columnar-lined esophagus with and without intestinal (Barrett's) metaplasia

Barrett's esophagus is diagnosed when goblet cells are found in the lower esophageal mucosa. However, the distribution of these cells is patchy and they may not represent the earliest marker of intestinal metaplasia. Cdx2 is a transcription factor whose expression in normal tissues is restricted to intestinal-type epithelium. Its distribution in the columnar-lined esophagus with and without intestinal metaplasia has been seldom studied. We evaluated Cdx2 expression in lower esophageal biopsies from 90 patients with endoscopic diagnosis of short segment Barrett's esophagus, including 45 consecutive cases showing intestinal metaplasia (goblet cells present in hematoxylin eosin and/or Alcian blue stains) and 45 consecutive cases without goblet cells. 25 samples of cardiac-type mucosa without intestinal metaplasia biopsied from the stomach served as controls. All cases with intestinal metaplasia revealed Cdx2 reactivity in goblet cells and adjacent nongoblet columnar cells. Dysplastic foci, seen in five cases from this group, were Cdx2 positive. In the group without goblet cells, Cdx2 was focally expressed by columnar cells in 17 (38%) cases. All control cases were Cdx2 negative. Strips of Alcian blue-positive nongoblet columnar cells ('columnar blues') were observed in 11 (24%) of the cases without intestinal metaplasia. All these foci were Cdx2 negative. In conclusion, Cdx2 is a highly sensitive marker for Barrett's esophagus. It is also expressed in a significant minority of cases of columnar-lined esophagus without goblet cells, suggesting that it may detect intestinal phenotypic modifications in the absence of goblet cells. Accordingly, Cdx2 immunostaining could help identify patients with Barrett's metaplasia in cases where no goblet cells are visible in biopsies from the columnar-lined esophagus. Finally, lack of Cdx2 expression in the 'columnar blues' suggests that these cells are not diagnostic of intestinal metaplasia.

Expression pattern of CK7, CK20, CDX-2, and villin in intestinal-type sinonasal adenocarcinoma

BACKGROUND

Intestinal-type sinonasal adenocarcinoma (ITAC) is an uncommon neoplasm, which resembles adenocarcinoma of the gastrointestinal tract. ITAC occurs sporadically or in association with occupational exposure to hardwood dust and other agents.

AIMS

To investigate the phenotype and possible pathogenetic mechanisms of primary sinonasal and nasopharyngeal adenocarcinomas by staining for cytokeratin 7 (CK7), CK20, CDX-2, and villin.

METHODS

Twelve sporadic sinonasal and nasopharyngeal adenocarcinomas were stained with monoclonal antibodies to CK7, CK20, CDX-2, and villin. The ITACs were classified as papillary, colonic, solid, mixed, or mucinous types.

RESULTS

The diagnosis of ITAC was confirmed in 10 cases: five were colonic type and five were papillary. One was a sinonasal papillary low grade adenocarcinoma, and one a papillary nasopharyngeal adenocarcinoma, and these tumours were CK7 positive, but CK20, CDX-2, and villin negative. All ITACs were positive for CK20, CDX-2, and villin, and six were CK7 positive. One ITAC had a focus of intestinal metaplasia away from the invasive carcinoma.

CONCLUSIONS

Sinonasal ITACs have a distinctive phenotype, with all cases expressing CK20, CDX-2, and villin. Most ITACs also express CK7, although a proportion of tumours are CK7 negative. ITAC seems to be preceded by intestinal metaplasia of the respiratory mucosa, which is accompanied by a switch to an intestinal phenotype. Although ITACs are morphologically similar, differences in cytokeratin expression patterns suggest two distinct types. The expression pattern of CK7, CK20, CDX-2, and villin positive may be useful in separating these tumours from other non-ITAC adenocarcinomas of the sinonasal tract and nasopharynx.

Pathologically and biologically distinct types of epithelium in intraductal papillary mucinous neoplasms: delineation of an "intestinal" pathway of carcinogenesis in the pancreas

Although general characteristics of intraductal papillary mucinous neoplasms (IPMNs) and their delineation from other pancreatic tumors have been well established, several issues regarding their biology and management remain unresolved. It has been noted briefly by us and other authors that there are different types of papillae in IPMNs; however, their frequency, biologic significance, and clinical relevance are unknown. In this study, the association of different papillary patterns with clinical, pathologic, and biologic parameters was studied in 74 IPMNs, and the expression profile of CDX2 (a specific marker and one of the key determinants of intestinal "programming," and a tumor suppressor) was determined immunohistochemically in addition to MUC1 (a marker of an "aggressive" phenotype in pancreatic neoplasia) and MUC2 ("intestinal type mucin," a marker of the "indolent" phenotype, and a tumor suppressor). The patterns of papillae identified and their association with these parameters were as follows: 1) The intestinal-type (Yonezawa's dark-cell type), similar to villous adenomas, was seen in 26 of 74 (35%) cases. The majority harbored carcinoma in situ (85%) or borderline atypia (15%). They tended to be large (mean, 5.5 cm). Most expressed CDX2 (95%) and MUC2 (92%) but not MUC1 (8%). This type was more commonly associated with colloid-type invasion (14 of 16 invasive carcinomas were of colloid type). 2) The pancreatobiliary type, characterized by arborizing papillae lined by cuboidal cells resembling papillary neoplasms of the biliary tract, was present in 22% of the cases. These were mostly graded as carcinoma in situ (94%); they rarely expressed CDX2 (6%) or MUC2 (19%) but often showed MUC1 labeling (44%). This pattern was more commonly associated with the tubular type of invasive carcinoma and had a slight tendency for a more aggressive clinical course. 3) The null type was characterized by abundant apical mucin and basally located nuclei, similar to the gastric foveolar epithelium. Thirty-one percent of IPMNs had this type of papillae, but this pattern was also present in the background of other IPMNs and in the cystic components of most cases as well. Most pure null-type IPMNs were devoid of complexity and consequently classified as adenoma (48%). They tended to be small (mean, 2.6 cm), were often negative for CDX2, MUC1, and MUC2, and were rarely associated with invasive carcinoma. 4) Some IPMNs (12%) exhibited features that were difficult to classify, and 2 cases had a mixture of pancreatobiliary and intestinal types of papillae. In conclusion, IPMNs include pathologically and biologically distinct epithelial patterns. CDX2 and MUC2 expression is relatively specific for the intestinal type papillae, confirming that these IPMNs indeed exhibit intestinal differentiation. Their close association with colloid carcinoma, which also shows consistent MUC2 and CDX2 expression, supports the existence of an intestinal pathway of carcinogenesis. This "metaplastic" pathway may reflect different genetic events in the development of these IPMNs, and the presence of intestinal differentiation may potentially be used in prognostication and stratification of patients into appropriate treatment categories.