title: Detection of hypermethylated RIZ1 gene in primary tumor, mouth, and throat rinsing fluid, nasopharyngeal swab, and peripheral blood of nasopharyngeal carcinoma patient.
abstract: OBJECTIVE
  The aims of this study are to examine the methylation status of the Fn2 RIZ1 gene in nasopharyngeal (NP) tumors and nasopharyngeal carcinoma (NPC) cell lines and to evaluate the clinical value of methylated RIZ1 gene in body fluid samples of NPC patients.
  
  
  METHODS
  Methylation status of RIZ1 was evaluated by MSP on CNE-2 and M1 cell lines, 30 tumor biopsies, and their matched body fluid samples, including mouth and throat (M & T) rinsing fluid, NP swabs, plasma, and buffy coat. Normal controls included 8 normal NP biopsies and body fluid samples from 29 healthy volunteers. Sequencing was performed on MSP products from one NP tumor and one M & T rinsing fluid. Transcription of the RIZ1 gene before and after 5-aza-2'-deoxycytidine treatment was examined on CNE-2.
  
  
  RESULTS
  The methylated RIZ1 gene was detected in both CNE-2 and M1, 18 (60%) NP tumors, but not in any of the normal controls. Of 30 matched body fluid samples, methylated RIZ1 DNA was found in 11 (37%) NP swabs, 9 (30%) M & T rinsing fluid, 7 (23%) plasma, and 3 (10%) buffy coat samples. Sequencing analysis confirmed all cytosines to uracils conversion, excluding cytosines in CpG dinucleotides in methylated PCR products. Promoter methylation correlated with loss of RIZ1 mRNA expression, and 5-aza-2'-deoxycytidine treatment restored its expression in CNE-2.
  
  
  CONCLUSIONS
  Our results suggest that promoter hypermethylation of the RIZ1 gene is commonly found in NPC. Its detection in body fluid samples of NPC patients but not in normal controls indicates that it is worth to further evaluate its clinical application in assisting screening of NPC and monitoring recurrence after treatment.
authors.affiliation: Department of Surgery, The University of Hong Kong, Hong Kong, People's Republic of China.
authors.forename: Hsiao Wen
authors.initials: HW
authors.lastname: Chang
authors.forename: Amy
authors.initials: A
authors.lastname: Chan
authors.forename: Dora Lai Wan
authors.initials: DL
authors.lastname: Kwong
authors.forename: William Ignace
authors.initials: WI
authors.lastname: Wei
authors.forename: Jonathan Shun Tong
authors.initials: JS
authors.lastname: Sham
authors.forename: Anthony Po Wing
authors.initials: AP
authors.lastname: Yuen
mesh_terms: D001374:Azacitidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D002277:Carcinoma / Q000097:blood / Q000235:genetics* / Q000378:metabolism*; D016022:Case-Control Studies; D004247:DNA / Q000378:metabolism; D019175:DNA Methylation; D004268:DNA-Binding Proteins / Q000235:genetics*; D000077209:Decitabine; D011495:Histone-Lysine N-Methyltransferase; D006801:Humans; D009055:Mouth / Q000378:metabolism*; D009303:Nasopharyngeal Neoplasms / Q000097:blood / Q000235:genetics* / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics*; D010614:Pharynx / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D013447:Sulfites / Q000494:pharmacology; D014157:Transcription Factors / Q000235:genetics*; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured
chemical_list: D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D012333:RNA, Messenger; D013447:Sulfites; D014157:Transcription Factors; D000077209:Decitabine; D004247:DNA; D011495:Histone-Lysine N-Methyltransferase; C093563:PRDM2 protein, human; D001374:Azacitidine