Methylation in esophageal carcinogenesis

Histone Modifying Enzymes as Targets for Therapeutic Intervention in Oesophageal Adenocarcinoma

Oesophageal adenocarcinoma (OAC) has a dismal prognosis, where curable disease occurs in less than 40% of patients, and many of those with incurable disease survive for less than a year from diagnosis. Despite the widespread use of systematic chemotherapy in OAC treatment, many patients receive no benefit. New treatments are urgently needed for OAC patients. There is an emerging interest in epigenetic regulators in cancer pathogenesis, which are now translating into novel cancer therapeutic strategies. Histone-modifying enzymes (HMEs) are key epigenetic regulators responsible for dynamic covalent histone modifications that play roles in both normal and dysregulated cellular processes including tumorigenesis. Several HME inhibitors are in clinical use for haematological malignancies and sarcomas, with numerous on-going clinical trials for their use in solid tumours. This review discusses the current literature surrounding HMEs in OAC pathogenesis and their potential use in targeted therapies for this disease.

Decreased expression and aberrant methylation of Raf kinase inhibitory protein gene in esophageal squamous cell carcinoma

Raf kinase inhibitory protein (RKIP) gene is considered to be a suppressor of metastasis involved in various carcinomas. In the present study, we observed that promoter methylation repressed the expression of RKIP in TE-13 cell line. 5-Aza treatment and stable transfection of RKIP resulted in a significant inhibition of TE-13 cell proliferation. The promoter hypermethylation of RKIP was found to occur in dysplastic tissues and a close correlation was noted between RKIP methylation and the loss of mRNA and protein expression of the gene in ESCC specimens. In summary, RKIP may act as a tumor suppressor gene in esophageal cancer.

LINE-1 hypomethylation in noncancerous esophageal mucosae is associated with smoking history

BACKGROUND

Cancer cells exhibit two types of DNA methylation alterations: global DNA hypomethylation and site-specific CpG island promoter hypermethylation. Selected gene promoter hypermethylation in normal esophageal mucosae has attracted attention as a surrogate marker for the epigenetic field defect induced by smoking and/or drinking in esophageal squamous cell carcinoma (ESCC). However, the significance of global DNA hypomethylation for field cancerization remains unclear.

METHODS

By using histologically normal esophageal mucosa samples from 109 ESCC cases and 20 autopsy cases without ESCCs, we measured long interspersed nucleotide element 1 (LINE-1) methylation levels by pyrosequencing, which correlates with global DNA methylation level.

RESULTS

LINE-1 methylation levels in normal esophageal mucosae of ESCC patients were significantly lower than those of autopsy individuals (P = 0.017). LINE-1 methylation of noncancerous mucosae ranged 68.3-93.0 on a 0-100 scale (mean 81.7, median 82.2, standard deviation 5.9). LINE-1 hypomethylation was significantly associated with smoking history (P = 0.014 for smoking duration; P = 0.0017 for number of cigarettes per day; P = 0.0002 for tobacco pack-year). LINE-1 methylation was not associated with alcohol drinking or age at diagnosis.

CONCLUSIONS

A history of tobacco use was significantly associated with LINE-1 hypomethylation in noncancerous esophageal mucosae of ESCC patients. These results support the potential of LINE-1 methylation level as an indicator of epigenetic field for ESCC cancerization, particularly when caused by tobacco smoking.

Non-Invasive Detection of Esophageal Cancer using Genetic Changes in Circulating Cell-Free DNA

Cell free DNA (cfDNA) is a genetic biomarker that is present in serum or plasma in high concentration in many types of cancer. Identification of circulating cancer related DNA molecules in serum or plasma is a non-invasive tool for early diagnosis and prognosis in many cancer patients. For this review, study selection and data extraction were performed by the authors. Detection of point mutations, microsatellite alterations, DNA hypermethylations and losses of heterozygosity in circulating cell free DNA have been characterized in esophagus cancer. Application of circulating cell free DNA as a biomarker, provide the best opportunity for constructing non-invasive tests for early detection, prognosis and management of cancer patients, after therapy in many types of cancer.

Decreased expression of WWOX in the development of esophageal squamous cell carcinoma

The WW domain-containing oxidoreductase (WWOX) gene, located on chromosome 16q23.3-24.1 in the region recognized as the common fragile site FRA16D is considered to be a tumor suppressor gene involved in various carcinomas. The present study was to investigate the alterations of WWOX expression and its correlation with polymorphism, the level of WWOX loss of heterozygosity (LOH), and methylation status in esophageal squamous cell carcinoma (ESCC). Immunohistochemistry and RT-PCR methods were used, respectively, to examine the protein and mRNA expression of WWOX in ESCC tissues. PCR-RFLP, PCR-SSLP, and MSP approach were used, respectively, to detect polymorphisms of rs3764340, rs2548861, and rs1079635 site, the level of LOH, and WWOX methylation status. Family history of upper gastrointestinal cancer (UGIC) significantly increased the risk of developing ESCC. Protein and mRNA expression of WWOX was reduced in ESCC tumor tissues and was associated with LOH and hypermethylation of the gene. The G allele of rs3764340 significantly elevated the risk of developing ESCC and was associated with TNM stage. LOH at the WWOX loci was observed in 41.4% tumors. The hypermethylation of promoter and exon1 of WWOX was found to be occurred in dysplastic tissues and the methylation frequency of WWOX in ESCC tumor tissues was significantly higher than that in corresponding normal tissues and was associated with UGIC family history. In all, these results indicate that the WWOX gene may play an important role in the development of ESCC especially in individuals with UGIC family history.

Outcomes after trimodality therapy for esophageal cancer: the impact of histology on failure patterns

OBJECTIVES

This retrospective analysis of patients undergoing neoadjuvant chemoradiation followed by surgical resection was performed to determine if histology or pathologic response affected local-regional control (LRC), survival outcomes or patterns of failure.

METHODS

We performed a review of 164 patients who underwent neoadjuvant chemoradiation followed by surgical resection from 1992 to 2006 for esophageal cancer. Information on patient characteristics, pathologic response, failure patterns, and survival was collected. Survival was estimated by the Kaplan-Meier method, and Cox multivariable Regression model was used to analyze trends.

RESULTS

The median follow-up was 18 months and 27 months in surviving patients. The 3-year overall survival (OS) and LRC was 46% and 79%. The overall response for the entire cohort included a pathologic complete response (pCR) rate of 41.4%, 21.3% with microscopic residual disease (mRD) and 36.3% with gross residual disease (gRD). The 3-year OS of patients who achieved a pCR versus mRD versus gRD was 58%, 53%, and 29%. OS was significantly improved in patients with a pCR and mRD compared with gRD (P = 0.001). On multivariate analysis both pCR and mRD correlated with an improved OS. Squamous cell cancers (SCC) had a higher rate of pCR than adenocarcinomas (AC), 54% versus 34.8% (P = 0.01). The 3 year LRC for patients with SCC and AC was 100% and 71% (P = 0.03). Among SCC with recurrence, there were no local failures and all failed distantly (P = 0.001).

CONCLUSIONS

Patients with microscopic residual disease following trimodality therapy had similar outcomes to patients achieving a pCR. Patients with SCC were more likely to achieve a pCR, and had a higher propensity to fail distantly when compared with patients with AC. This data should be considered in the design of future clinical trials.

DNA methylation in thoracic neoplasms

Thoracic neoplasms, which include lung cancers, esophageal carcinoma, and thymic epithelial tumors, are the leading causes of tumor-related death and a major health concern worldwide. The development of neoplasms is a multistep process involving both genetic and epigenetic alterations. A growing body of research provides evidence that aberrant DNA methylation, including DNA hypermethylation in promoter regions, global DNA hypomethylation and the overexpression of DNA methyltransferases, plays an important role in tumorigenesis. In this review, we summarize published observations of methylation pattern disruptions in thoracic tumors, and discuss how these abnormalities contribute to the development of cancers. We review recent findings showing that suppressing the activity of the DNA methylating enzymes DNMTs can have potent anti-cancer effects, and discuss the possibility of developing novel therapies for thoracic tumors based on DNMT inhibition.

Reduced membranous and ectopic cytoplasmic expression of DSC2 in esophageal squamous cell carcinoma: an independent prognostic factor

Desmocollin 2, a desmosomal component, is a key membrane glycoprotein critically involved in cell-cell adhesion and the maintenance of normal tissue architectures in epithelia. Reports exploring the link of desmocollin expression to cancers are limited. The aim of this study was to investigate the expression of desmocollin 2 in esophageal squamous cell carcinoma and, in particular, to determine the extent to which the patterns of desmocollin 2 expression correlated with the clinical parameters. Desmocollin 2 expression was evaluated in 308 cases of esophageal squamous cell carcinoma using immunohistochemistry. Western blotting and reverse transcriptase polymerase chain reaction were performed to characterize the relative expression levels of desmocollin 2 isoforms. The results indicated that desmocollin 2 expression was reduced significantly in esophageal cancer in both protein and messenger RNA levels and that this reduction was associated with poor survival (P = .011). The expression of desmocollin 2 was prominent in normal esophageal epithelia and highly differentiated esophageal tumors, but was reduced or absent in poorly differentiated tumor specimens. Furthermore, in 74.7% of tumor tissues, desmocollin 2 immunoreactivity displayed an abnormal cytoplasmic localization that was correlated with poor tumor differentiation (P < .001), regional lymph node metastasis (P < .001), pathologic tumor-node-metastasis stages (P < .001), and poor prognosis (P = .048). Multivariate analysis showed that desmocollin 2 expression level was an independent prognostic factor for esophageal squamous cell carcinoma. These data suggest that desmocollin 2 is involved in the transformation and development of esophageal tumors and that desmocollin 2 expression level and intracellular localization may serve as a predictor for patient outcomes.

Pharmacokinetics and pharmacogenomics in esophageal cancer chemoradiotherapy

Esophageal cancer is one of the most lethal malignancies. Surgical resection of the tumor from the primary site has been the standard treatment, especially for localized squamous cell carcinoma, but considerable clinical efforts during the last decade have resulted in novel courses of treatment. These options include chemoradiotherapy, consisting of a continuous infusion of 5-fluorouracil (5-FU), cisplatin (CDDP), and concurrent radiation. Given the substantial inter- and/or intra-individual variation in clinical outcome, future improvements will likely require the incorporation of a novel anticancer drug, pharmacokinetically guided administration of CDDP or 5-FU, and identification of potential responders by patient genetic profiling prior to treatment. In this review, the latest information on incidence, risk factors, biomarkers, therapeutic strategies, and the pharmacokinetically guided or genotype-guided administration of CDDP and 5-FU is summarized for future individualization of esophageal cancer treatment.

Epigenetic targets in cancer epidemiology

Recently, it has been shown that epigenetic changes are involved in early stages of tumorigenesis, and they may trigger the genetic events leading to tumor development. In cancer epidemiology, there are several epigenetic alterations involved, such as DNA hypermethylation, DNA hypomethylation, and chromatin modifications with critical roles in the initiation and progression of human neoplasms. This chapter discusses the hypermethylation profiles of several tumor types, including bladder, brain, breast, colorectal, ovarian, prostate, and other cancers as well as DNA hypomethylation phenomena together with the chromatin modifications and their role in the complex mechanism of epigenetic silencing. Moreover, the involvement of environmental exposures in cancer susceptibility is addressed. In conclusion, these epigenetic changes are important characteristics of human neoplasia, and a better understanding of these modifications and the link between these changes for each tumor type will be important in early diagnosis of cancer and cancer prevention.

Promoter methylation in cytology specimens as an early detection marker for esophageal squamous dysplasia and early esophageal squamous cell carcinoma

The incidence of esophageal squamous cell carcinoma (ESCC) is very high in northern China. This cancer has a very poor prognosis, mostly because it is usually diagnosed at a late stage. Detection at an earlier stage can dramatically improve prognosis. Microscopic evaluation of esophageal balloon cytology (EBC) specimens has been the most common method for early detection of ESCC, but this technique is limited by low sensitivity and specificity. The use of molecular markers may improve these screening characteristics. This study evaluates whether measurement of gene methylation in EBC specimens may have utility for the detection of esophageal squamous dysplasia and early ESCC. We evaluated the presence of methylation in eight genes shown to be methylated in ESCC in previous studies in EBC specimens from 147 patients with endoscopic biopsy diagnoses ranging from normal mucosa to severe squamous dysplasia. Methylation status was determined using quantitative methylation-specific PCR techniques. The sensitivity and specificity of methylation of each individual gene and of combinations of these genes to detect biopsyproven high-grade (moderate or severe) squamous dysplasia were determined. For individual genes, the sensitivities ranged from 9% to 34% and the specificities ranged from 77% to 99%. Using a panel of four genes (AHRR, p16INK4a, MT1G, and CLDN3) resulted in sensitivity and specificity of 50% and 68%, respectively. This study suggests that evaluation of gene methylation in EBC samples may have utility for early detection of esophageal squamous dysplasia and early ESCC; however, identification of more sensitive methylation markers will be required for development of a clinically useful screening test.

[Do locally advanced esophageal cancer still need surgery?]

Results of surgery in locally advanced esophageal carcinomas (T3 and/or N1) are disappointing. Concomitant chemoradiotherapy (RTCT) gave equivalent survival results in many phase II studies. Two randomized trials (French and German) compared surgery or additional RTCT after a first phase of RTCT. Both drew the same conclusions, that is surgery did not improve overall survival but increased postoperative mortality. However, local control was found better in the surgical arms, and in some subgroups, esophagectomy improved disease-free survival suggesting that some patients may benefit from surgery. After preoperative RTCT, absence of residual disease in the surgical specimen (pathological complete response) occurs in 15 to 30%; these patients underwent a radical surgery without any benefit but with high risk of morbidity and mortality. Nevertheless, it is still difficult to select this sub-population: CT-scan or endoscopy with biopsies have a low sensitivity and specificity. 18-FDG-PET-scan, performed after or during the RTCT, is able to increase sensitivity, but only preliminary results with small populations are available. No biological factor of chemoradiosensitivity (p53, NfkappaB, p21...) could predict who will respond or not. Another approach is to reserve surgery only to patients with a demonstrated local failure (salvage surgery) but the feasibility of this technique is still debated. Finally, local relapses are frequent after RTCT and optimisation of the current schedules is mandatory to improve oncologic results. Unfortunately, increasing the radiation dose did not improve local control and showed more toxicities. New drugs as taxanes, oxaliplatine, or targeted therapies are tested in on-going phase III trial.

Molecular biological challenges in he treatment of esophageal adenocarcinoma

Despite improvements in detection and treatment, patients diagnosed with esophageal cancer continue to have a poor prognosis, with an increase in 5-year survival rates from 6 to 16% over the past 25 years. In the last decade there has been growing support for neoadjuvant therapy in patients with esophageal cancer. However, in approximately 30-60% of the patients no objective response is achieved after neoadjuvant chemotherapy and/or radiotherapy. These patients do not benefit from neoadjuvant therapy but do suffer from toxic side effects, and appropriate surgical treatment is delayed. Advances in molecular biology and new molecular technologies could possibly contribute to improvement of response to neoadjuvant therapy. This review categorizes the genetic and molecular alterations related to esophageal adenocarcinoma and links these changes to targeting therapy and prediction of tumor response to neoadjuvant chemotherapy and/or radiotherapy.

Chemoradiation in the Management of Esophageal Cancer

The combination of chemotherapy, fluorouracil and cisplatin, and radiation has improved outcome for patients with esophageal cancer. A randomized controlled trial confirmed a long-term survival benefit when this chemotherapy was added to radiotherapy for squamous cell carcinoma, but the approach has not been definitively assessed in patients with adenocarcinoma. Preoperative chemoradiotherapy has been tested in numerous phase II studies and underpowered or flawed phase III studies. Nevertheless, collectively, the evidence strongly suggests that preoperative chemoradiotherapy improves outcome, and thus, this strategy has become a standard treatment option. Attempts to improve outcome by intensifying conventional cytotoxic drugs or increasing the radiation dose have not been successful. Camptothecin and taxane-based regimens combined with radiation have altered the toxicity profile, but substantial improvement in survival outcomes has yet to be demonstrated. Future improvements will likely require the incorporation of targeted agents that add minimally to existing toxicity, the use of molecular predictors of response to individualize selection of the chemotherapeutic regimen, and early identification of responders such that therapy might be altered dynamically.