Epigenetic patterns in the progression of esophageal adenocarcinoma.

Esophageal adenocarcinoma (EAC) arises after normal squamous mucosa undergoes metaplasia to specialized columnar epithelium (intestinal metaplasia or Barrett's esophagus), which can then ultimately progress to dysplasia and subsequent malignancy. Epigenetic studies of this model have thus far been limited to the DNA methylation analysis of a few genes. In this study, we analyzed a panel of 20 genes using a quantitative, high-throughput methylation assay, METHYLIGHT: We used this broader approach to gain insight into concordant methylation behavior between genes and to generate epigenomic fingerprints for the different histological stages of EAC. Our study included a total of 104 tissue specimens from 51 patients with different stages of Barrett's esophagus and/or associated adenocarcinoma. We screened 84 of these samples with the full panel of 20 genes and found distinct classes of methylation patterns in the different types of tissue. The most informative genes were those with an intermediate frequency of significant hypermethylation [ranging from 15% (CDKN2A) to 60% (MGMT) of the samples]. This group could be further subdivided into three classes, according to the absence (CDKN2A, ESR1, and MYOD1) or presence (CALCA, MGMT, and TIMP3) of methylation in normal esophageal mucosa and stomach, or the infrequent methylation of normal esophageal mucosa accompanied by methylation in all normal stomach samples (APC). The other genes were less informative, because the frequency of hypermethylation was below 5% (ARF, CDH1, CDKN2B, GSTP1, MLH1, PTGS2, and THBS1), completely absent (CTNNB1, RB1, TGFBR2, and TYMS1), or ubiquitous (HIC1 and MTHFR), regardless of tissue type. Each class undergoes unique epigenetic changes at different steps of disease progression of EAC, suggesting a step-wise loss of multiple protective barriers against CpG island hypermethylation. The aberrant hypermethylation occurs at many different loci in the same tissues, suggestive of an overall deregulation of methylation control in EAC tumorigenesis. However, we did not find evidence for a distinct group of tumors with a CpG island methylator phenotype. Finally, we found that normal and metaplastic tissues from patients with evidence of associated dysplasia or cancer had a significantly higher incidence of hypermethylation than similar tissues from patients with no further progression of their disease. The fact that the samples from these two groups of patients were histologically indistinguishable, yet molecularly distinct, suggests that the occurrence of such hypermethylation may provide a clinical tool to identify patients with premalignant Barrett's who are at risk for further progression.

Fields of aberrant CpG island hypermethylation in Barrett's esophagus and associated adenocarcinoma.

Esophageal adenocarcinoma (EAC) is thought to develop through a multistage process in which Barrett's metaplasia progresses through low- and high-grade dysplasia to invasive cancer. Transcriptional silencing of tumor suppressor genes by promoter CpG island hypermethylation has been observed in many types of human cancer. Analysis of CpG island hypermethylation in EAC has thus far been limited to the CDKN2A (p16) gene. In this study, we extend the methylation analysis of EAC to include three other genes, APC, CDH1 (E-cadherin), and ESR1 (ER, estrogen receptor alpha), in addition to CDKN2A. Molecular analysis can provide insight into the complex relationships between tissues with different histologies in Barrett's esophagus and associated adenocarcinoma. Therefore, we have mapped the spatial distribution of methylation patterns in six esophagectomy cases in detail. Hypermethylation of the four CpG islands was analyzed by the MethyLight technique in 107 biopsies derived from these six patients for a total of 428 methylation analyses. Our results show that normal esophageal squamous epithelium is unmethylated at all four CpG islands. CDH1 is unmethylated in most other tissue types as well. Hypermethylation of ESR1 is seen at high frequency in inflammatory reflux esophagitis and at all subsequent stages, whereas APC and CDKN2A hypermethylation is found in Barrett's metaplasia, dysplasia, and EAC. When it occurs, hypermethylation of APC, CDKN2A, and ESR1 is usually found in a large contiguous field, suggesting either a concerted methylation change associated with metaplasia or a clonal expansion of cells with abnormal hypermethylation.

Saffron chemoprevention in biology and medicine: a review.

A growing body of evidence indicate that carotenoids possess anticarcinogenic, anti-mutagenic and immunomodulating effects. Saffron obtained from the dried stigmas of Crocus sativus L., is an important spice, rich in carotenoids, consumed commonly in different parts of the world. Our laboratory first reported the anticancer activity of saffron extract (dimethyl-crocetin) against a wide spectrum of murine tumors and human leukemia cell lines. The present report reviews the role of saffron in serving as a chemopreventive agent in modifying cancer risk. Dose-dependent cytotoxic effect to carcinoma, sarcoma and leukemia cells in vitro were noted. Saffron delayed ascites tumor growth and increased the life span of the treated mice compared to untreated controls by 45-120%. In addition, it delayed the onset of papilloma growth, decreased incidence of squamous cell carcinoma and soft tissue sarcoma in treated mice. Understanding the mechanisms of action of saffron have been solitarily based on their carotenoid-like action. Our results indicated significant inhibition in the synthesis of nucleic acids but not protein synthesis. It appears now that saffron (dimethyl-crocetin) disrupts DNA-protein interactions e.g. topoisomerases II, important for cellular DNA synthesis.