## Abstract An etiologic role for human papillomavirus (HPV) infections in either head and neck (HNC) or esophageal carcinogenesis remains debatable. Patients with head and neck cancer are at high risk for developing a second esophageal squamous cell cancer (ESCC). The aim of our study was to deter
DNA global hypomethylation in squamous cell head and neck cancer associated with smoking, alcohol consumption and stage
โ Scribed by Ian M. Smith; Wojciech K. Mydlarz; Suhail K. Mithani; Joseph A. Califano
- Publisher
- John Wiley and Sons
- Year
- 2007
- Tongue
- French
- Weight
- 103 KB
- Volume
- 121
- Category
- Article
- ISSN
- 0020-7136
No coin nor oath required. For personal study only.
โฆ Synopsis
Abstract
Epigenetic changes have been implicated in the pathogenesis of solid tumors, including head and neck squamous cell carcinoma (HNSCC). Prior efforts have primarily examined regional promoter hypermethylation as a silencer of tumor suppressor gene expression. To analyze the global state of methylation in the HNSCC genome, we utilize pyrosequencing of repetitive elements (LINEs) to compare the state of global methylation in HNSCC to normal aerodigestive mucosa. 137 samples (119 HNSCC tumors and 18 normal mucosal tissues) were digested to extract DNA and subjected to bisulfite treatment. Treated DNA was amplified using PCR primers for the repetitive LINEs sequence and produced a heterogeneous sample of products, from many genomic loci. These products were pyrosequenced to quantitatively evaluate their global genomic methylation status. HNSCC specimens showed global hypomethylation, with a mean level of genomic methylation of 46.8% methylated with a standard deviation of 9.0. Conversely, the normal upper airway mucosa had a global methylation level of 54.0 and a standard deviation of 4.6 (MannโWhitney p value < 0.001). The tumor specimens also showed an increasing degree of hypomethylation associated with advanced tumor stage (ANOVA pโvalue of 0.003). About 67% of HNSCC's are globally hypomethylated when evaluated against the minimum level of methylation in the normal mucosal specimens. Degree of global hypomethylation was associated with smoking history, alcohol use and stage in univariate analysis (pโvalue 0.02), however, only HNSCC diagnosis remained significant on multivariate analysis. Despite the presence of regional promoter hypermethylation, HNSCC demonstrates global genomic hypomethylation. The effects of stage, alcohol use and smoking on global hypomethylation were not independently significant. ยฉ 2007 WileyโLiss, Inc.
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