Intestinal or gastric? The unsolved dilemma of Barrett's metaplasia

Interobserver reproducibility in pathologist interpretation of columnar-lined esophagus

Confirmation of endoscopically suspected esophageal metaplasia (ESEM) requires histology, but confusion in the histological definition of columnar-lined esophagus (CLE) is a longstanding problem. The aim of this study is to evaluate interpathologist variability in the interpretation of CLE. Thirty pathologists were invited to review three ten-case sets of CLE biopsies. In the first set, the cases were provided with descriptive endoscopy only; in the second and the third sets, ESEM extent using Prague criteria was provided. Moreover, participants were required to refer to a diagnostic chart for evaluation of the third set. Agreement was statistically assessed using Randolph's free-marginal multirater kappa. While substantial agreement in recognizing columnar epithelium (K = 0.76) was recorded, the overall concordance in clinico-pathological diagnosis was low (K = 0.38). The overall concordance rate improved from the first (K = 0.27) to the second (K = 0.40) and third step (K = 0.46). Agreement was substantial when diagnosing Barrett's esophagus (BE) with intestinal metaplasia or inlet patch (K = 0.65 and K = 0.89), respectively, in the third step, while major problems in interpretation of CLE were observed when only cardia/cardia-oxyntic atrophic-type epithelium was present (K = 0.05-0.29). In conclusion, precise endoscopic description and the use of a diagnostic chart increased consistency in CLE interpretation of esophageal biopsies. Agreement was substantial for some diagnostic categories (BE with intestinal metaplasia and inlet patch) with a well-defined clinical profile. Interpretation of cases with cardia/cardia-oxyntic atrophic-type epithelium, with or without ESEM, was least consistent, which reflects lack of clarity of definition and results in variable management of this entity.

Definition of Barrett's esophagus dysplasia: are we speaking the same language?

The definition of Barrett's esophagus (BE) is still a matter of debate. The diagnostic criteria adopted around the world for both BE and BE-related pre-cancerous lesions are inconsistent, particularly between Eastern and Western pathologists. From a clinical perspective, these different clinico-biological approaches may affect how the literature is interpreted, with detrimental effects on the clinical management of patients. The present review focuses on the major discrepancies in the field, covering both the non-neoplastic and the pre-cancerous lesions associated with Barrett's disease.

Transcribed ultraconserved noncoding RNAs (T-UCR) are involved in Barrett's esophagus carcinogenesis

Barrett's esophagus (BE) involves a metaplastic replacement of native esophageal squamous epithelium (Sq) by columnar-intestinalized mucosa, and it is the main risk factor for Barrett-related adenocarcinoma (BAc). Ultra-conserved regions (UCRs) are a class non-coding sequences that are conserved in humans, mice and rats. More than 90% of UCRs are transcribed (T-UCRs) in normal tissues, and are altered at transcriptional level in tumorigenesis. To identify the T-UCR profiles that are dysregulated in Barrett's mucosa transformation, microarray analysis was performed on a discovery set of 51 macro-dissected samples obtained from 14 long-segment BE patients. Results were validated in an independent series of esophageal biopsy/surgery specimens and in two murine models of Barrett's esophagus (i.e. esophagogastric-duodenal anastomosis). Progression from normal to BE to adenocarcinoma was each associated with specific and mutually exclusive T-UCR signatures that included up-regulation of uc.58-, uc.202-, uc.207-, and uc.223- and down-regulation of uc.214+. A 9 T-UCR signature characterized BE versus Sq (with the down-regulation of uc.161-, uc.165-, and uc.327-, and the up-regulation of uc.153-, uc.158-, uc.206-, uc.274-, uc.472-, and uc.473-). Analogous BE-specific T-UCR profiles were shared by human and murine lesions. This study is the first demonstration of a role for T-UCRs in the transformation of Barrett's mucosa.

MicroRNA Expression Profiling in the Histological Subtypes of Barrett's Metaplasia

OBJECTIVES

The histological definition of Barrett's esophagus (BE) is debated, particularly regarding the phenotype of its metaplastic columnar epithelium. Histologically proven intestinal metaplasia (IM) was the sine qua non condition for a diagnosis of BE but, more recently, non-intestinalized (i.e., cardiac gastric-type; GM) columnar metaplasia has been re-included in the spectrum of Barrett's histology. MicroRNAs modulate cell commitment, and are also reportedly dysregulated in Barrett's carcinogenesis. This study investigates miRNA expression in the histological spectrum of esophageal columnar metaplastic changes, specifically addressing the biological profile of GM vs. IM.

METHODS

A study was performed to discover microRNA microarray in 30 matching mucosa samples obtained from 10 consecutive BE patients; for each patient, biopsy tissue samples were obtained from squamous, GM and intestinalized epithelium. Microarray findings were further validated by qRT-PCR analysis in another bioptic series of 75 mucosa samples.

RESULTS

MicroRNA profiling consistently disclosed metaplasia-specific microRNA signatures. Six microRNAs were significantly dysregulated across the histological phenotypes considered; five of them (two overexpressed (hsa-miR-192; -miR-215) and three under-expressed (hsa-miR-18a*; -miR-203, and -miR-205)) were progressively dysregulated in the phenotypic sequence from squamous to gastric-type, to intestinal-type mucosa samples.

CONCLUSIONS

A consistent microRNA expression signature underlies both gastric- and intestinal-type esophageal metaplasia. The pattern of microRNA dysregulation suggests that GM may further progress to IM. The clinico-pathological implications of these molecular profiles prompt further study on the "personalized" cancer risk associated with each of these metaplastic transformations.

Advanced precancerous lesions within the GI tract: the molecular background

The mainstream carcinogenic processes involved within the gastrointestinal tract are characterized by phenotypic multistep progression cascades that eventually result in full-blown cancers. In this scenario, the understanding of the molecular dysregulations underlying the precancerous lesions is increasing but still remains incomplete. However, in recent years, the enthusiastic rise of innovative technologies (i.e., next-generation sequencing, high-throughput microarray analysis, mass spectrometry based proteomics) and the unexpected discovery of new classes of biomarkers (i.e., miRNA, long-noncoding RNAs) prompted new strength in the exploration of the accurate and comprehensive molecular characterization of premalignant and malignant neoplastic lesions. The challenge ahead lies in the reliable identification of disease progression-specific targets to enable molecular testing in the clinical management of the secondary prevention of gastrointestinal cancers.

Early HER2 dysregulation in gastric and oesophageal carcinogenesis

AIMS

To explore human epidermal growth factor receptor 2 (HER2) status in the histological phenotypes [metaplasia, intraepithelial neoplasia (IEN, i.e. dysplasia), and adenocarcinoma] involved in the morphogenesis of both intestinal-type gastric cancer (GC) and Barrett's adenocarcinoma (BAc).

METHODS AND RESULTS

A consecutive series of 275 samples of stomach and oesophagus tissue (representing the whole spectrum of the phenotypic changes involved in gastric and Barrett's carcinogenesis) was studied. HER2 status was assessed by applying two immunohistochemistry (IHC) protocols, using the antibodies 4B5 and CB11. Dual-colour silver chromogenic in-situ hybridization (SISH) was also performed on the same tissue samples. In both oesophageal and gastric samples, the rate of HER2 overexpression rose significantly from low-grade to high-grade IEN to adenocarcinoma (P < 0.001), with the two IHC protocols showing consistent staining (consistency 95%; k = 0.78; P < 0.001). Intratumour heterogeneity was documented in both GC and BAc (using both IHC protocols). The rate of HER2 amplification (using SISH) increased significantly along with IEN dedifferentiation (P < 0.001). Neither native nor metaplastic mucosa samples (obtained from either stomach or oesophagus) ever showed HER2 amplification. There was excellent agreement between HER2 amplification and protein overexpression (both IHC protocols: SISH/4B5--consistency 97.8%, k = 0.89, P < 0.001; SISH/CB11-consistency 97.8%, k = 0.91, P < 0.001).

CONCLUSIONS

There is early involvement of HER2 dysregulation (amplification and protein overexpression) in both gastric (intestinal-type) and Barrett's oncogenesis.

Anterior gradient 2 profiling in Barrett columnar epithelia and adenocarcinoma

Barrett esophagus is the precancerous lesion leading to Barrett adenocarcinoma. The natural history of Barrett metaplasia and its neoplastic progression are still controversial. Anterior gradient 2 is up-regulated in both Barrett intestinal metaplasia and Barrett adenocarcinoma, but no information is available on anterior gradient 2 expression in the spectrum of the phenotypic changes occurring in the natural history of Barrett adenocarcinoma (Barrett esophagus cardiac-type metaplasia, Barrett esophagus intestinal metaplasia, low-grade intraepithelial neoplasia [formerly called low-grade dysplasia], and high-grade intraepithelial neoplasia [formerly called high-grade dysplasia]). Applying immunohistochemistry and reverse transcription and quantitative real-time polymerase chain reaction, this study addressed the role of anterior gradient 2 in Barrett carcinogenesis. Anterior gradient 2 expression was assessed semiquantitatively in 125 consecutive biopsy samples in the adenocarcinoma spectrum arising in Barrett esophagus (Barrett esophagus cardiac-type metaplasia, 25; Barrett esophagus intestinal metaplasia, 25; low-grade intraepithelial neoplasia, 25; high-grade intraepithelial neoplasia, 25; Barrett adenocarcinoma, 25). Additional biopsy samples of esophageal squamous mucosa (n=25) served as controls. Anterior gradient 2 messenger RNA expression was also tested (reverse transcription and quantitative real-time polymerase chain reaction) in a different series of 40 samples (esophageal squamous mucosa, 10; Barrett esophagus cardiac-type metaplasia, 10; Barrett esophagus intestinal metaplasia, 10; Barrett adenocarcinoma, 10). Anterior gradient 2 was never expressed in squamous esophageal epithelium but consistently overexpressed (to much the same degree) in the whole spectrum of Barrett disease (Barrett esophagus cardiac-type metaplasia, Barrett esophagus intestinal metaplasia, low-grade intraepithelial neoplasia, high-grade intraepithelial neoplasia, and Barrett adenocarcinoma). Anterior gradient 2 messenger RNA was expressed significantly more in Barrett esophagus cardiac-type metaplasia, Barrett esophagus intestinal metaplasia, and Barrett adenocarcinoma than in native squamous epithelium (P<.001), with no significant differences between the 3 groups. Anterior gradient 2 overexpression affects the whole spectrum of the metaplastic/neoplastic lesions involved in Barrett carcinogenesis. This study supports the biological similarity of the nonintestinal and intestinal types of Barrett metaplasia as precursors of Barrett adenocarcinoma.

miRNAs in precancerous lesions of the gastrointestinal tract

In spite of the well-established understanding of the phenotypic lesions occurring in the shift from native epithelia to invasive (adeno) carcinoma, the molecular typing of the precancerous changes in the gastrointestinal tract remains unreliable. In recent years, no biomarkers have aroused as much interest as the miRNAs, a class of non-coding RNA molecules that function as endogenous silencers of numerous target genes. Aberrant miRNA expression is a hallmark of human disease, including cancer. Unlike most mRNAs, miRNAs are both long-living in vivo and very stable in vitro. Such characteristics allow their testing in paraffin-embedded tissue samples, which is essential in the biological profiling of small (phenotypically characterized) preneoplastic lesions of the gastrointestinal tract (as well as in other fields of human pathology). The upcoming challenge lies in the reliable identification of disease-specific targets of dysregulated miRNAs, to enable miRNA testing in the clinical management of the secondary prevention of gastrointestinal cancer.

Microscopic esophagitis and Barrett's esophagus: the histology report

Gastro-esophageal reflux disease (GERD) is the most common digestive disease in industrialized countries (Europe and North America) and is associated with microscopic changes in the squamous epithelium. However, biopsy is not presently included in the routine diagnostic flow chart of GERD. In contrast, esophageal biopsy is mandatory when diagnosing Barrett's esophagus. High quality histology reports are necessary to provide information on diagnosis and can also be important for research and epidemiological studies. It has been evident for decades that pathology reports vary between institutions and even within a single institution. Standardization of reporting is the best way to ensure that information necessary for patient management is included in pathology reports. This paper details the histological criteria for diagnosing GERD-associated microscopic esophagitis, other forms of esophagitis with specific features and columnar metaplasia in the lower esophagus (Barrett's esophagus). It provides a detailed description of appropriate sampling criteria, individual lesions and how they contribute to the histology report.

Aurora kinase A in Barrett's carcinogenesis

In Barrett's mucosa, both aneuploidy and TP53 mutations are consistently recognized as markers of an increased risk of Barrett's adenocarcinoma. Overexpression of the mitotic kinase encoding gene (AURKA) results in chromosome instability (assessed from the micronuclei count) and ultimately in aneuploidy. Eighty-seven esophageal biopsy samples representative of all the phenotypic lesions occurring in the multistep process of Barrett's carcinogenesis (gastric metaplasia in 25, intestinal metaplasia in 25, low-grade intraepithelial neoplasia in 16, high-grade intraepithelial neoplasia in 11, and Barrett's adenocarcinoma in 10) were obtained from long segments of Barrett's mucosa. Twenty-five additional biopsy samples of native esophageal mucosa were used for control purposes. In all tissue samples, the immunohistochemical expression of both AURKA and TP53 gene products was scored; and the micronuclei index was calculated. AURKA immunostaining increased progressively and significantly along with dedifferentiation of the histologic phenotype (P < .001). Nine of 10 Barrett's adenocarcinomas showed AURKA immunostaining. AURKA expression correlated significantly with p53 expression and the micronuclei index (both Ps < .001). AURKA overexpression is significantly associated with Barrett's mucosa progressing to Barrett's adenocarcinoma and contributes to esophageal carcinogenesis via chromosome instability. The identification of AURKA as a novel molecular target of cancer progression in Barrett's mucosa provides a lead for the development of new therapeutic approaches in Barrett's mucosa patients.