DNA Hypomethylation and Ovarian Cancer Biology

Hypomethylation of some portions of the genome and hypermethylation of others are very frequent in human cancer. The hypomethylation often involves satellite 2 (Sat2) DNA in the juxtacentromeric (centromere-adjacent) region of chromosome 1. In this study, we analyzed methylation in centromeric and juxtacentromeric satellite DNA in 115 ovarian cancers, 26 non-neoplastic ovarian specimens, and various normal somatic tissue standards. We found that hypomethylation of both types of satellite DNA in ovarian samples increased significantly from non-neoplastic toward cancer tissue. Furthermore, strong hypomethylation was significantly more prevalent in tumors of advanced stage or high grade. Importantly, extensive hypomethylation of Sat2 DNA in chromosome 1 was a highly significant marker of poor prognosis (relative risk for relapse, 4.1, and death, 9.4) and more informative than tumor grade or stage. Also, comparing methylation of satellite DNA and 15 5′ gene regions, which are often hypermethylated in cancer or implicated in ovarian carcinogenesis, we generally found no positive or negative association between methylation changes in satellite DNA and in the gene regions. However, hypermethylation at two loci, CDH13 (at 16q24) and RNR1 (at 13p12), was correlated strongly with lower levels of Sat2 hypomethylation. The CDH13/Sat2 epigenetic correlation was seen also in breast cancers. We conclude that satellite DNA hypomethylation is an important issue in ovarian carcinogenesis as demonstrated by: (a) an increase from non-neoplastic tissue toward ovarian cancer; (b) an increase within the ovarian cancer group toward advanced grade and stage; and (c) the finding that strong hypomethylation was an independent marker of poor prognosis.

[1]  A. Feinberg.  Cancer epigenetics takes center stage. , 2001, Proceedings of the National Academy of Sciences of the United States of America.

[2]  F. Cavalli,et al.  Phase II study of 5-Aza-2′-deoxycytidine in advanced ovarian carcinoma , 1990 .

[3]  J. Hindley,et al.  Cloning of human satellite III DNA: different components are on different chromosomes. , 1979, Nucleic acids research.

[4]  T. Visakorpi,et al.  Genomewide DNA hypomethylation is associated with alterations on chromosome 8 in prostate carcinoma , 2002, Genes, chromosomes & cancer.

[5]  W. Lau,et al.  Hypomethylation of chromosome 1 heterochromatin DNA correlates with q-arm copy gain in human hepatocellular carcinoma. , 2001, The American journal of pathology.

[6]  R. Jaenisch,et al.  Chromosomal Instability and Tumors Promoted by DNA Hypomethylation , 2003, Science.

[7]  J. Herman,et al.  Germ-line variants in methyl-group metabolism genes and susceptibility to DNA methylation in normal tissues and human primary tumors. , 2002, Cancer research.

[8]  Rudolf Jaenisch,et al.  DNA hypomethylation leads to elevated mutation rates , 1998, Nature.

[9]  M. Widschwendter,et al.  Methylated DNA as a possible screening marker for neoplastic disease in several body fluids , 2003, Expert review of molecular diagnostics.

[10]  Christian B. Woods,et al.  Satellite DNA hypomethylation in karyotyped Wilms tumors. , 2003, Cancer genetics and cytogenetics.

[11]  H. Ozçelik,et al.  Epigenetic factors controlling the BRCA1 and BRCA2 genes in sporadic ovarian cancer. , 2002, Cancer research.

[12]  S. Saga,et al.  Hypomethylation of the MN/CA9 promoter and upregulated MN/CA9 expression in human renal cell carcinoma , 2001, British Journal of Cancer.

[13]  A. Feinberg,et al.  Hypomethylation distinguishes genes of some human cancers from their normal counterparts , 1983, Nature.

[14]  R. Kerbel,et al.  Possible epigenetic mechanisms of tumor progression: Induction of high‐frequency heritable but phenotypically unstable changes in the tumorigenic and metastatic properties of tumor cell populations by 5‐azacytidine treatment , 1984, Journal of cellular physiology. Supplement.

[15]  A. Grañena,et al.  Cadherin-13, a mediator of calcium-dependent cell-cell adhesion, is silenced by methylation in chronic myeloid leukemia and correlates with pretreatment risk profile and cytogenetic response to interferon alfa. , 2003, Journal of clinical oncology : official journal of the American Society of Clinical Oncology.

[16]  T Tanaka,et al.  Identification by cDNA microarray of genes involved in ovarian carcinogenesis. , 2000, Cancer research.

[17]  K. Nephew,et al.  DNA methylation and ovarian cancer. I. Analysis of CpG island hypermethylation in human ovarian cancer using differential methylation hybridization. , 2001, Gynecologic oncology.

[18]  E. Viégas-Péquignot,et al.  Specific induction of uncoiling and recombination by azacytidine in classical satellite-containing constitutive heterochromatin. , 1993, Cytogenetics and cell genetics.

[19]  F. Ledeist,et al.  An embryonic-like methylation pattern of classical satellite DNA is observed in ICF syndrome. , 1993, Human molecular genetics.

[20]  J W Gray,et al.  An approach to analysis of large-scale correlations between genome changes and clinical endpoints in ovarian cancer. , 2000, Cancer research.

[21]  D. Lockhart,et al.  Analysis of gene expression profiles in normal and neoplastic ovarian tissue samples identifies candidate molecular markers of epithelial ovarian cancer. , 2001, Proceedings of the National Academy of Sciences of the United States of America.

[22]  Alicia Samuels,et al.  Cancer Statistics, 2003 , 2003, CA: a cancer journal for clinicians.

[23]  Y. Benjamini,et al.  Controlling the false discovery rate in behavior genetics research , 2001, Behavioural Brain Research.

[24]  M. Kitajima,et al.  Correlation of postoperative recurrence in hepatocellular carcinoma with demethylation of repetitive sequences , 2002, Oncogene.

[25]  Mimi C. Yu,et al.  Alterations in DNA methylation are early, but not initial, events in ovarian tumorigenesis. , 1997, British Journal of Cancer.

[26]  S. Gasser,et al.  Positions of Potential:Nuclear Organization and Gene Expression , 2001, Cell.

[27]  P. Laird,et al.  Prolonged culture of normal chorionic villus cells yields ICF syndrome-like chromatin decondensation and rearrangements , 2003, Cytogenetic and Genome Research.

[28]  P. Laird,et al.  Hypomethylation and hypermethylation of DNA in Wilms tumors , 2002, Oncogene.

[29]  P. Laird,et al.  Adenocarcinoma Epigenetic Patterns in the Progression of Esophageal Updated Version , 2001 .

[30]  A. Sakurada,et al.  The H-cadherin (CDH13) gene is inactivated in human lung cancer , 1998, Human Genetics.

[31]  M. Ehrlich,et al.  Preferential induction of chromosome 1 multibranched figures and whole-arm deletions in a human pro-B cell line treated with 5-azacytidine or 5-azadeoxycytidine. , 1997, Cytogenetics and cell genetics.

[32]  David Sidransky,et al.  Adenomatous polyposis coli gene promoter hypermethylation in non-small cell lung cancer is associated with survival , 2001, Oncogene.

[33]  P. Yan,et al.  Hypermethylation of ribosomal DNA in human breast carcinoma , 2000, British Journal of Cancer.

[34]  P. Laird,et al.  Fields of aberrant CpG island hypermethylation in Barrett's esophagus and associated adenocarcinoma. , 2000, Cancer research.

[35]  S. Baylin,et al.  Hypomethylation of pericentromeric DNA in breast adenocarcinomas , 1998, International journal of cancer.

[36]  H. Willard,et al.  Chromosome-specific alpha satellite DNA from human chromosome 1: hierarchical structure and genomic organization of a polymorphic domain spanning several hundred kilobase pairs of centromeric DNA. , 1987, Genomics.

[37]  K. Nephew,et al.  DNA methylation in ovarian cancer. II. Expression of DNA methyltransferases in ovarian cancer cell lines and normal ovarian epithelial cells. , 2001, Gynecologic oncology.

[38]  A. Veronese,et al.  Loss of methylation at chromosome 11p15.5 is common in human adult tumors , 2002, Oncogene.

[39]  M. Ehrlich,et al.  DNA hypomethylation and unusual chromosome instability in cell lines fromICF syndrome patients , 2000, Cytogenetic and Genome Research.

[40]  S. S. Smith,et al.  The tumorigenicity of 5-azacytidine in the male Fischer rat. , 1984, Carcinogenesis.

[41]  G. Pfeifer,et al.  Hypermethylation of the CpG island of the RASSF1A gene in ovarian and renal cell carcinomas , 2001, International journal of cancer.

[42]  M. Widschwendter,et al.  DNA methylation in serum of breast cancer patients: an independent prognostic marker. , 2003, Cancer research.

[43]  F. Cavalli,et al.  Phase II study of 5-aza-2'-deoxycytidine in advanced ovarian carcinoma. The EORTC Early Clinical Trials Group. , 1990, European journal of cancer.

[44]  M. Ehrlich,et al.  DNA methylation in cancer: too much, but also too little , 2002, Oncogene.

[45]  Robert Brown,et al.  Primary ovarian carcinomas display multiple methylator phenotypes involving known tumor suppressor genes. , 2001, The American journal of pathology.

[46]  M. Ehrlich,et al.  DNA demethylation and pericentromeric rearrangements of chromosome 1. , 1997, Mutation research.

[47]  G. Stoner,et al.  Test for carcinogenicity of food additives and chemotherapeutic agents by the pulmonary tumor response in strain A mice. , 1973, Cancer research.

[48]  S. Hirohashi,et al.  Correlation of DNA hypomethylation at pericentromeric heterochromatin regions of chromosomes 16 and 1 with histological features and chromosomal abnormalities of human breast carcinomas. , 2002, The American journal of pathology.

[49]  N. Dubrawsky.  Cancer statistics , 1989, CA: a cancer journal for clinicians.

[50]  C. Iacobuzio-Donahue,et al.  Frequent hypomethylation of multiple genes overexpressed in pancreatic ductal adenocarcinoma. , 2003, Cancer research.

[51]  P. Laird,et al.  MethyLight: a high-throughput assay to measure DNA methylation. , 2000, Nucleic acids research.

[52]  Peter A. Jones,et al.  The fundamental role of epigenetic events in cancer , 2002, Nature Reviews Genetics.

[53]  B. Johansson,et al.  A breakpoint map of recurrent chromosomal rearrangements in human neoplasia , 1997, Nature Genetics.

[54]  M. Ehrlich,et al.  The 5-methylcytosine content of DNA from human tumors. , 1983, Nucleic acids research.

[55]  Taylor Murray,et al.  Cancer statistics, 1999 , 1999, CA: a cancer journal for clinicians.

[56]  Y. Bignon,et al.  Major oncogenes and tumor suppressor genes involved in epithelial ovarian cancer (review). , 2000, International journal of oncology.

[57]  M. Ehrlich,et al.  Satellite DNA hypomethylation vs. overall genomic hypomethylation in ovarian epithelial tumors of different malignant potential. , 1999, Mutation research.

[58]  K. Kinzler,et al.  Genetic instabilities in human cancers , 1998, Nature.

[59]  A. Godwin,et al.  Hypomethylation of the Synuclein γ Gene CpG Island Promotes Its Aberrant Expression in Breast Carcinoma and Ovarian Carcinoma , 2003 .

[60]  N. Dillon,et al.  Binding of Ikaros to the λ5 promoter silences transcription through a mechanism that does not require heterochromatin formation , 2001, The EMBO journal.

[61]  R. Jaenisch,et al.  Induction of Tumors in Mice by Genomic Hypomethylation , 2003, Science.

[62]  J. Weber,et al.  Review of the clinical experience with 5-azacytidine and 5-aza-2'-deoxycytidine in solid tumors. , 2002, Current opinion in investigational drugs.

[63]  J. Berek,et al.  Ovarian cancer: epidemiology, biology, and prognostic factors. , 2000, Seminars in surgical oncology.