title: Alu methylation in serum from patients with nasopharyngeal carcinoma.
abstract: BACKGROUND
  Nasopharyngeal carcinoma (NPC) is a common cancer in Southern China and Southeast Asia. Alu elements are among the most prevalent repetitive sequences and constitute 11% of the human genome. Although Alu methylation has been evaluated in many types of cancer, few studies have examined the levels of this modification in serum from NPC patients.
  
  
  OBJECTIVE
  To compare the Alu methylation levels and patterns between serum from NPC patients and normal controls.
  
  
  METHODS
  Sera from 50 NPC patients and 140 controls were examined. Quantitative combined bisulfite restriction analysis-Alu (qCOBRA-Alu) was applied to measure Alu methylation levels and characterize Alu methylation patterns. Amplified products were classified into four patterns according to the methylation status of 2 CpG sites: hypermethylated (methylation at both loci), partially methylated (methylation of either of the two loci), and hypomethylated (unmethylated at both loci).
  
  
  RESULTS
  A comparison of normal control sera with NPC sera revealed that the latter presented a significantly lower methylation level (p=0.0002) and a significantly higher percentage of hypomethylated loci (p=0.0002). The sensitivity of the higher percentage of Alu hypomethyted loci for distinguishing NPC patients from normal controls was 96%.
  
  
  CONCLUSIONS
  Alu elements in the circulating DNA of NPC patients are hypomethylated. Moreover, Alu hypomethylated loci may represent a potential biomarker for NPC screening.
authors.affiliation: Research Division, National Cancer Institute, Bangkok, Thailand E-mail : Nakarinkit@gmail.com.
authors.forename: Danai
authors.initials: D
authors.lastname: Tiwawech
authors.forename: Ratakorn
authors.initials: R
authors.lastname: Srisuttee
authors.forename: Prakasit
authors.initials: P
authors.lastname: Rattanatanyong
authors.forename: Charoenchai
authors.initials: C
authors.lastname: Puttipanyalears
authors.forename: Nakarin
authors.initials: N
authors.lastname: Kitkumthorn
authors.forename: Apiwat
authors.initials: A
authors.lastname: Mutirangura
mesh_terms: D000328:Adult; D000368:Aged; D020087:Alu Elements / Q000235:genetics*; D002277:Carcinoma; D016022:Case-Control Studies; D004247:DNA / Q000097:blood / Q000235:genetics; D019175:DNA Methylation; D005260:Female; D005500:Follow-Up Studies; D015894:Genome, Human; D006801:Humans; D008297:Male; D008875:Middle Aged; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000097:blood* / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011379:Prognosis
chemical_list: D004247:DNA