High frequency of hypermethylation at the 14-3-3 σ locus leads to gene silencing in breast cancer

Anne T. Ferguson, Ella Evron, Christopher B. Umbricht, Tej K. Pandita, Timothy A. Chan, Heiko Hermeking, Jeffrey R. Marks, Anouk R. Lambers, P. Andrew Futreal, Martha R. Stampfer, Saraswati Sukumar

Research output: Contribution to journalArticle

Abstract

Expression of 14-3-3 σ (σ) is induced in response to DNA damage, and causes cells to arrest in G2. By SAGE (serial analysis of gene expression) analysis, we identified σ as a gene whose expression is 7-fold lower in breast carcinoma cells than in normal breast epithelium. We verified this finding by Northern blot analysis. Remarkably, σ mRNA was undetectable in 45 of 48 primary breast carcinomas. Genetic alterations at σ such as loss of heterozygosity were rare (1/20 informative cases), and no mutations were detected (0/34). On the other hand, hypermethylation of CpG islands in the σ gene was detected in 91% (75/82) of breast tumors and was associated with lack of gene expression. Hypermethylation of σ is functionally important, because treatment of σ-non-expressing breast cancer cell lines with the drug 5-aza-2'-deoxycytidine resulted in demethylation of the gene and synthesis of σ mRNA. Breast cancer cells lacking σ expression showed increased number of chromosomal breaks and gaps when exposed to γ-irradiation. Therefore, it is possible that loss of σ expression contributes to malignant transformation by impairing the G2 cell cycle checkpoint function, thus allowing an accumulation of genetic defects. Hypermethylation and loss of σ expression are the most consistent molecular alterations in breast cancer identified so far.

Original languageEnglish (US)
Pages (from-to)6049-6054
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume97
Issue number11
DOIs
StatePublished - May 23 2000

    Fingerprint

ASJC Scopus subject areas

  • General

Cite this

Ferguson, A. T., Evron, E., Umbricht, C. B., Pandita, T. K., Chan, T. A., Hermeking, H., Marks, J. R., Lambers, A. R., Futreal, P. A., Stampfer, M. R., & Sukumar, S. (2000). High frequency of hypermethylation at the 14-3-3 σ locus leads to gene silencing in breast cancer. Proceedings of the National Academy of Sciences of the United States of America, 97(11), 6049-6054. https://doi.org/10.1073/pnas.100566997