p16 gene mutations in Barrett's esophagus in gastric metaplasia - intestinal metaplasia - dysplasia - adenocarcinoma sequence

Diagnosis and Management of Barrett's Esophagus

Barrett's esophagus is a metaplastic change of esophageal mucosa, which can be characterized by its salmon-colored lining and the presence of columnar epithelium with goblet cells. It is a well-established precancerous state of esophageal adenocarcinoma, a tumor with very poor survival rates, which incidence is rapidly growing. Despite numerous research, the debate about its diagnosis and management is still ongoing. This article aims to provide an overview of the current recommendations and new discoveries regarding the subject.

High-resolution genomic alterations in Barrett's metaplasia of patients who progress to esophageal dysplasia and adenocarcinoma

The main risk factor for esophageal dysplasia and adenocarcinoma (DAC) is Barrett's esophagus (BE), characterized by intestinal metaplasia. The critical genomic mechanisms that lead to progression of nondysplastic BE to DAC remain poorly understood and require analyses of longitudinal patient cohorts and high-resolution assays. We tested BE tissues from 74 patients, including 42 nonprogressors from two separate groups of 21 patients each and 32 progressors (16 in a longitudinal cohort before DAC/preprogression-BE and 16 with temporally concurrent but spatially separate DAC/concurrent-BE). We interrogated genome-wide somatic copy number alterations (SCNAs) at the exon level with high-resolution SNP arrays in DNA from formalin-fixed samples histologically confirmed as nondysplastic BE. The most frequent abnormalities were SCNAs involving FHIT exon 5, CDKN2A/B or both in 88% longitudinal BE progressors to DAC vs. 24% in both nonprogressor groups (p = 0.0004). Deletions in other genomic regions were found in 56% of preprogression-BE but only in one nonprogressor-BE (p = 0.0004). SCNAs involving FHIT exon 5 and CDKN2A/B were also frequently detected in BE temporally concurrent with DAC. TP53 losses were detected in concurrent-BE but not earlier in preprogression-BE tissues of patients who developed DAC. CDKN2A/p16 immunohistochemistry showed significant loss of expression in BE of progressors vs. nonprogressors, supporting the genomic data. Our data suggest a role for CDKN2A/B and FHIT in early progression of BE to dysplasia and adenocarcinoma that warrants future mechanistic research. Alterations in CDKN2A/B and FHIT by high-resolution assays may serve as biomarkers of increased risk of progression to DAC when detected in BE tissues.

Biomarkers for Barrett's esophagus - a contemporary review

INTRODUCTION

Esophageal adenocarcinoma (EAC) has a poor 5-year survival rate (10%-18%), and incidence has increased dramatically in the past three decades. Barrett's esophagus (BE) is the precursor lesion to EAC and is the replacement of the normally squamous lined esophagus with columnar cells that develop an intestinal phenotype characterized by the presence of goblet cells. Given the known precursor state, EAC is amenable to screening and surveillance strategies (analogous to colon cancer). However, unlike from colon cancer screening, BE poses challenges that make effective screening difficult. Robust and concerted effort is under way to find biomarkers of BE. Areas covered: This review summarizes current known biomarkers for BE. These include dysplasia, genomic markers, and gene expression alterations that occur early in the dysplasia/carcinoma sequence. Expert commentary: Despite the tremendous breadth of work in studying molecular advances, the ideal biomarker for BE has not yet been discerned. This review comments on innovations in the field of BE research that combine state-of-the-art molecular advances with simple technologies.

A systematic review of epigenetic biomarkers in progression from non-dysplastic Barrett's oesophagus to oesophageal adenocarcinoma

OBJECTIVES

The objective of this systematic review is to identify and summarise studies which examine epigenetic biomarkers in patients with Barrett's oesophagus (BO) and their association with progression to oesophageal adenocarcinoma (OADC). BO is a precursor lesion for OADC. There is no clinical test to predict patients who are likely to progress to OADC. An epigenetic biomarker could predict patients who are at high risk of progression from BO to OADC which could facilitate earlier diagnosis and spare those unlikely to develop cancer from regular invasive surveillance endoscopy.

SETTING

A systematic search was conducted of the following databases: MEDLINE, MEDLINE in Process, EMBASE, Cochrane Central, ISI Conference Proceedings Citation Index and the British Library's ZETOC. Studies were conducted in secondary and tertiary care settings.

PARTICIPANTS

All studies measuring epigenetic change in patients over 18 years old who progressed from non-dysplastic BO to OADC were included. Genetic, in vitro and studies which did not measure progression in the same patient cohort were excluded. Study inclusion and risk of bias of individual eligible studies were assessed in duplicate by two reviewers using a modified Quality in Prognostic Studies tool.

RESULTS

14 studies met the inclusion criteria. 42 epigenetic markers were identified, and 5 studies developed models aiming to predict progression to OADC.

CONCLUSIONS

The evidence from this systematic review is suggestive of a role for p16 as an epigenetic biomarker for the progression of BO to OADC.

PROSPERO NUMBER

CRD42016038654.

An electrochemiluminescence biosensor for detection of CdkN2A/p16 anti-oncogene based on functional electrospun nanofibers and core-shell luminescent composite nanoparticles

An electrochemiluminescence (ECL) biosensor based on functional electrospun nanofibers for hybridization detection of specific CdkN2A/p16 anti-oncogene at trace level via binding luminescent composite nanoparticles for signal amplification has been developed. The carboxylated multiwalled carbon nanotubes (MWCNTs) doped polycaprolactam 6 (PA6) electrospun nanofibers (PA6-MWCNTs) was prepared via electrospinning, which served as the nanosized backbones for silica nanoparticles (SiO₂) electrodeposition. The functional electrospun nanofibers (PA6-MWCNTs-SiO₂) used as supporting scaffolds for single-stranded DNA1 (ssDNA1) immobilization can dramatically increase the amount of DNA attachment and the sensitivity of hybridization. The sandwich construction of ssDNA1-CdkN2A/p16 anti-oncogene -tri(2,2'-bipyridyl)ruthenium(II) (Ru(bpy)₃²⁺)/silver nanoparticles (AgNPs) doped gold (Au) core-shell luminescent composite nanoparticles (RuAg@AuNPs)-labeled ssDNA2 (RuAg@Au-ssDNA2) was fabricated through a hybridization reaction. It was observed that high amount of doped Ru(bpy)₃²⁺ in RuAg@AuNPs successfully amplify the recognition signal by adding tripropylamine (TPrA). The change of ECL intensity was found to have a linear relationship in respect to the logarithm of the CdkN2A/p16 anti-oncogene concentrations in the wide range of 1.0 × 10^-15~1.0 × 10^-12 M, with a detection limit of 0.5 fM (S/N = 3) which is comparable or better than that in reported anti-oncogene assays. Excellent sensitivity and selectivity make the developed biosensor a promising tool for the detection of tumor biomarkers.

P16ink4a Subcellular Expression Patterns in Colorectal Adenocarcinoma, Adenoma and Non-Neoplastic Tissue Samples

Background: Colorectal cancer (CRC) is one of the most common neoplasms with high mortality at advanced stages worldwide. Thus diagnosis of CRC at an early stage with sensitive molecular methods is a high priority. The aim of this study was to evaluate P16ink4a subcellular expression patterns in colorectal adenocarcinoma, adenoma and non-neoplastic tissue samples. Methods: A total of 137 colorectal formalin fixed paraffin-embedded tissue blocks from the pathology archives of Ali-Ebne-Abitaleb central hospital, Zahedan, Iran, were examined in three groups: adenocarcinoma (n= 63), adenoma (n= 38) and non-neoplastic (n= 36). The subcellular expression pattern was determined by immunocytochemistry. Data analysis was performed using Kruskal-Wallis and Fisher exact tests with the significance level set as p˂0.05. Results: P16ink4a subcellular localization was observed in three different patterns, nuclear+cytoplasmic (73.33%), cytoplasmic (13.33%) and nuclear (13.33%). In most samples, nuclear+cytoplasmic was the predominant subcellular pattern. However, a significant difference in P16ink4a subcellular expression patterns was observed along the non-neoplastic, adenoma, adenocarcinoma sequence (p˂0.001). An association with the histological tumor type was also noted (p=0.021). Conclusion: Considering variation in localization of P16ink4a under different pathological conditions, P16ink4a night be sensitive prognostic biomarker for benign colon lesions. Its use may improve strategies for screening, prognostic assessment and management of patients with CRC. Further studies are recommended in this field.

Morphological Features and Prognostic Significance of ARID1A-Deficient Esophageal Adenocarcinomas

Context.—

The clinicopathologic and prognostic significance of ARID1A mutation in esophageal adenocarcinoma (EAC) is unknown.

Objective.—

To determine the morphological correlates and prognostic significance of ARID1A-deficient EAC.

Design.—

One hundred twenty cases of primary EAC were evaluated for a predetermined set of histologic features and immunohistochemistry for ARID1A, p53, and MLH1 performed on EAC, as well as adjacent Barrett esophagus and Barrett esophagus–associated dysplasia, when feasible. Associations between categorical clinicopathologic variables were analyzed by Fisher exact test, and survival analysis was performed by a Cox proportional hazards analysis.

Results.—

The study group included 97 men and 23 women (mean age, 66 years). Loss of ARID1A expression was seen in 12 of 120 EACs (10%). ARID1A-deficient tumors showed a strong correlation with a medullary and mucinous phenotype, and 8 of 12 (67%) had at least one feature reminiscent of high microsatellite instability colon carcinomas (mucinous or medullary differentiation, marked intratumoral or peritumoral lymphoid infiltrate). A mutant p53 pattern was present in 52 of 120 EACs (43%) and showed no correlation with ARID1A deficiency (P > .05). MLH1 loss was present in only 2 of 120 EACs (2%); both of which were also deficient in ARID1A. ARID1A-deficient EACs showed a trend toward increased risk of nodal metastasis but had no effect on overall patient survival.

Conclusions.—

ARID1A-deficient EACs show a phenotype similar to colon cancer with high microsatellite instability but do not appear to have any prognostic significance. Concurrent MLH1 loss is not seen in most ARID1A-deficient tumors, suggesting that ARID1A may be a primary driver of carcinogenesis in a subset of EACs.

Biomarkers of Barrett's esophagus

Barrett’s esophagus is the strongest risk for esophageal adenocarcinoma (EAC). Metaplasia in patients with BE may progress to dysplasia and then invasive carcinoma. Well-defined diagnostic, progressive, predictive, and prognostic biomarkers are needed to identify the presence of the disease, estimate the risk of malignant transformation, and predict the therapeutic outcome and survival of EAC patients. There are many predictive and prognostic markers that lack substantial validation, and do not allow stratification of patients with gastroesophageal reflux disease in clinical practice for outcome and effectiveness of therapy. In this short review we summarize the current knowledge regarding possible biomarkers, focusing on the pathophysiologic mechanisms to improve prognostic and therapeutic approaches.

Role of p16 gene promoter methylation in gastric carcinogenesis: a meta-analysis

This meta-analysis was performed to evaluate the relationships between promoter DNA methylation in tumor suppressor gene p16 and gastric carcinogenesis. The PubMed, CISCOM, CINAHL, Web of Science, Google Scholar, EBSCO, Cochrane Library and CBM databases were searched for relevant articles published before November 1st, 2013 without any language restrictions. Meta-analysis was conducted using the STATA 12.0 software. Crude odds ratios (ORs) with 95% confidence intervals (95% CI) were calculated. Forty-seven clinical cohort studies that met all inclusion criteria were included in this meta-analysis. A total of 2,813 gastric cancer (GC) patients were assessed. Our meta-analysis results revealed that the frequencies of p16 promoter methylation in the GC tissues were higher than those of normal and adjacent tissues (Normal: OR = 23.04, 95% CI = 13.55-39.15, P < 0.001; Adjacent: OR = 4.42, 95% CI = 1.66-11.76, P = 0.003; respectively). Furthermore, we observed significant associations of p16 promoter methylation with TNM stage, histologic grade, invasive grade, lymph node metastasis of GC (TNM stage: OR = 3.60, 95% CI: 2.17-5.98, P < 0.001; Histologic grade: OR = 2.63, 95% CI: 1.55-4.45, P < 0.001; Invasive grade: OR = 3.44, 95% CI: 1.68-7.06, P = 0.001; Lymph node metastasis: OR = 2.68, 95% CI: 1.66-4.32, P < 0.001; respectively). However, there were no correlations of p16 promoter methylation with the TNM stage and Helicobacter pylori (HP) infection of GC (Tumor size: OR = 0.76, 95% CI: 0.14-4.07, P = 0.746; HP infection: OR = 1.31, 95% CI: 0.75-2.27, P = 0.342; respectively). Our findings provide empirical evidence that p16 promoter methylation may play an important role in gastric carcinogenesis. Thus, p16 promoter methylation may be a promising potential biomarker for the early diagnosis of GC.

Clonal selection and persistence in dysplastic Barrett's esophagus and intramucosal cancers after failed radiofrequency ablation

OBJECTIVES

Radiofrequency ablation (RFA) is used to successfully eliminate Barrett's esophagus (BE)-related dysplasia or intramucosal carcinoma and aims to cause reversion to squamous epithelium. However, in 20% of cases RFA fails to return the epithelium to squamous phenotype. Follow-up studies show a similar dysplasia recurrence rate. We hypothesize that failed RFA is due to clonally mutated epithelial populations harbored in RFA-privileged sites and that RFA can select for the mutant clonal expansion.

METHODS

A longitudinal case series of 19 patients with BE and high-grade dysplasia or intramucosal carcinoma were studied. DNA was extracted from individual Barrett's glands, deep esophageal glands within mucosal resections and biopsy specimens before and after RFA. Mutations were identified by targeted sequencing of genes commonly mutated in Barrett's adenocarcinoma.

RESULTS

Five patients demonstrated persistent post-RFA pathology with persistent mutations, sometimes detected in deep esophageal glands or neighboring squamous epithelium after several rounds of RFA preceded by mucosal resection. Recurrence of pathology in three other patients was characterized by de novo mutations.

CONCLUSIONS

Protumorigenic mutations can be found in post-ablation squamous mucosa as well as in mutant deep esophageal glands; both are associated with dysplasia recurrence. Following RFA, non-dysplastic Barrett's epithelium can contain mutant clones that are found in a subsequent adenocarcinoma. Ablation may also drive the clonal expansion of pre-existing clones after a "bottleneck" created by the RFA. Overall, recurrence of dysplasia post RFA reflects the multicentric origins of Barrett's clones and highlights the role of clonal selection in carcinogenesis.

Crypt dysplasia in Barrett's oesophagus shows clonal identity between crypt and surface cells

Epithelial dysplasia is an important histological diagnosis signifying the presence of pre-invasive disease, usually needing intervention. However, the specific genetic changes responsible for the induction of this phenotypic change are unknown. Moreover, recent reports indicate that the dysplastic phenotype may not be immutable: in basal crypt dysplasia (CD), unequivocal dysplastic changes are seen in the crypts in Barrett's oesophagus and other pre-invasive lesions in the gastrointestinal tract, but the upper crypts and surface epithelium associated with these dysplastic crypts show the definitive morphology of a differentiated epithelium. The genotypic relationship between CD and the differentiated surface epithelium is presently unclear. We obtained 17 examples of CD: the lower and upper crypts and surface epithelium were differentially laser-microdissected from formalin-fixed, paraffin-embedded sections and mutations were sought in tumour suppressor genes frequently associated with progression in Barrett's oesophagus. We found two patients who both showed a c. C238T mutation in the CDKN2A (CDKN2AInk4A) gene and where the precise microanatomical relationships could be discerned: this mutation was present in both the CD at the crypt base and in the upper crypt and surface epithelium. We conclude that, in CD, the dysplastic basal crypt epithelium and the upper crypt and surface epithelium show clonal CDKN2A mutations, thus showing definitively that the surface epithelium is derived from the dysplastic crypt epithelium: the dysplastic phenotype is therefore not fixed and can be reversed. The mechanism of this change is unclear but may be related to the possibility that dysplastic cells can, probably early in their progression, respond to differentiation signals. However, it is also clear that a heavy mutational burden can be borne by crypts in the gastrointestinal tract without the development of phenotypic dysplasia. We are evidently some way from understanding the plasticity and the genotypic correlates of the dysplastic phenotype.

Predictive biomarkers for Barrett's esophagus: so near and yet so far

Barrett's esophagus (BE) is the strongest risk factor for the development of esophageal adenocarcinoma. However, the risk of cancer progression is difficult to ascertain in individuals, as a significant number of patients with BE do not necessarily progress to esophageal adenocarcinoma. There are several issues with the current strategy of using dysplasia as a marker of disease progression. It is subject to sampling error during biopsy acquisition and interobserver variability among gastrointestinal pathologists. Ideal biomarkers with high sensitivity and specificity are needed to accurately detect high-risk BE patients for early intervention and appropriate cost-effective surveillance. To date, there are no available molecular tests in routine clinical practice despite known genetic and epigenetic aberrations in the Barrett's epithelium. In this review, we present potential biomarkers for the prediction of malignant progression in BE. These include markers of genomic instability, tumor suppressor loci abnormalities, epigenetic changes, proliferation markers, cell cycle predictors, and immunohistochemical markers. Further work in translating biomarkers for routine clinical use may eventually lead to accurate risk stratification.