title: Alterations in DNA methylation are early, but not initial, events in ovarian tumorigenesis.
abstract: We compared global levels of DNA methylation as well as methylation of a specific locus (MyoD1) in ovarian cystadenomas, ovarian tumours of low malignant potential (LMP) and ovarian carcinomas to investigate the association between changes in DNA methylation and ovarian tumour development. As we realized that cystadenomas showed different methylation patterns from both LMP tumours and carcinomas, we verified their monoclonal origin as a means of confirming their true neoplastic nature. High-pressure liquid chromatographic (HPLC) analyses showed that global methylation levels in LMP tumours and carcinomas were 21% and 25% lower than in cystadenomas respectively (P = 0.0001 by one-way variance analysis). Changes in the methylation status of the MyoD1 locus were not seen in any of ten cystadenomas analysed but were present in five of ten LMP tumours and in five of ten carcinomas (P = 0.03). These findings suggest that alterations in DNA methylation are absent (or at least not as extensive) in ovarian cystadenomas, but are present in LMP tumours, the phenotypic features of which are intermediate between those of benign and malignant ovarian tumours. The results also emphasize the merit of distinguishing ovarian LMP tumours from cystadenomas, in spite of their similar clinical characteristics.
authors.affiliation: Department of Gynecologic Oncology, USC/Norris Comprehensive Cancer Center, University of Southern California School of Medicine, Los Angeles 90033-0800, USA.
authors.forename: P
authors.initials: P
authors.lastname: Cheng
authors.forename: C
authors.initials: C
authors.lastname: Schmutte
authors.forename: K F
authors.initials: KF
authors.lastname: Cofer
authors.forename: J C
authors.initials: JC
authors.lastname: Felix
authors.forename: M C
authors.initials: MC
authors.lastname: Yu
authors.forename: L
authors.initials: L
authors.lastname: Dubeau
mesh_terms: D015139:Blotting, Southern; D002277:Carcinoma / Q000235:genetics / Q000473:pathology / Q000601:surgery; D002851:Chromatography, High Pressure Liquid; D003537:Cystadenoma / Q000235:genetics / Q000473:pathology / Q000601:surgery; D019175:DNA Methylation; D017931:DNA Primers; D004273:DNA, Neoplasm / Q000032:analysis*; D005260:Female; D006801:Humans; D010051:Ovarian Neoplasms / Q000235:genetics* / Q000473:pathology* / Q000601:surgery; D010053:Ovary / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D011944:Receptors, Androgen / Q000235:genetics; D018911:Trinucleotide Repeats; D014960:X Chromosome
chemical_list: D017931:DNA Primers; D004273:DNA, Neoplasm; D011944:Receptors, Androgen