title: Quantification of CpG methylation at the 5'-region of XIST by pyrosequencing from human serum.
abstract: Aberrant methylation of X (inactive)-specific transcript (XIST) is common in serum derived from human prostate and testicular germ cell tumors. The direct quantification of XIST methylation is urgently required for clinical application because human serum contains both normal and cancer-originated XIST DNA. We directly quantitated the methylation percentage of three CpG sites (+947, +956, +971) from the 5'-region of XIST by pyrosequencing. The average methylation percentages at three CpG sites were 88% (+/-5.8) at CpG1, 98% (+/-3.4) at CpG2, and 92% (+/-5.6) at CpG3 from normal male (N = 19). From prostate cancer-derived sera, the average methylation percentage of XIST was 65% (+/-8.3) at CpG1, 82% (+/-10.9) at CpG2, and 74% (+/-4.4) at CpG3, which is lower than the normal XY serum DNA, but greater than normal XX serums. The methylation status of XIST also correlated with its gene expression in B-lymphoblastoid and prostate cancer cell lines. This method is sensitive for quantifying the small percentage change in the methylation status of XIST, and may be used for early diagnosis and monitoring of cancer in men using serum.
authors.affiliation: Functional Genomics Laboratory, CHA Research Institute, College of Medicine, Seongnam-si, Gyeongii-do, South Korea.
authors.forename: Min-Ae
authors.initials: MA
authors.lastname: Song
authors.forename: Jung-Hoon
authors.initials: JH
authors.lastname: Park
authors.forename: Kyoung-Sin
authors.initials: KS
authors.lastname: Jeong
authors.forename: Dong Soo
authors.initials: DS
authors.lastname: Park
authors.forename: Myung Seo
authors.initials: MS
authors.lastname: Kang
authors.forename: Suman
authors.initials: S
authors.lastname: Lee
mesh_terms: D020121:5' Untranslated Regions / Q000737:chemistry; D000368:Aged; D000369:Aged, 80 and over; D001483:Base Sequence; D018899:CpG Islands; D019175:DNA Methylation; D006801:Humans; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated / Q000097:blood* / Q000737:chemistry*; D017423:Sequence Analysis, RNA / Q000379:methods*
chemical_list: D020121:5' Untranslated Regions; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated; C077885:XIST non-coding RNA