Constitutive overexpression of CDC25A in primary human mammary epithelial cells results in both defective DNA damage response and chromosomal breaks at fragile sites

Maria Giulia Cangi, Sara Piccinin, Lorenza Pecciarini, Anna Talarico, Elena Dal Cin, Stefano Grassi, Alessandra Grizzo, Roberta Maestro, Claudio Doglioni

Research output: Contribution to journalArticle

Abstract

CDC25A phosphatase, an essential component of the cell cycle machinery, is also a key player in integrating the specific signals of checkpoint control in response to DNA damage. There are several lines of evidence that indicate a role for CDC25A in cancer development, consistent with the fact that its overexpression is detected in human cancers. In particular we previously reported that CDC25A is overexpressed also in early breast carcinoma. Recent data suggest that oncogene activation during early stages of tumor development causes DNA replication stress resulting in the induction of DNA damage response (DDR) and that the selection of cells defecting in their DDR could lead to malignant progression. To address how CDC25A overexpression contributes to breast cancer development we established a cell model in which CDC25A was constitutively overexpressed in hTERT-immortalized primary human mammary epithelial cells. At the earliest passages following CDC25A transduction we observed DDR signs associated with unscheduled DNA replication origins. In the latest passages DDR was significantly impaired and, even after ionizing radiation exposition, cells failed to induce G1 and G2 checkpoints; moreover DNA replication stress conditions, such as aphidicolin treatment, highlighted increased fragile site breakages and destabilized chromosomes just in these latest passages cells. Our data suggest that CDC25A overexpression, pushing the cell through the cell cycle transitions, induces DDR alterations that might enhance genomic instability.

Original languageEnglish
Pages (from-to)1466-1471
Number of pages6
JournalInternational Journal of Cancer
Volume123
Issue number6
DOIs
Publication statusPublished - Sep 15 2008

Keywords

  • Breast
  • CDC25A
  • Cell cycle checkpoint
  • DNA damage response
  • Fragile sites

ASJC Scopus subject areas

  • Cancer Research
  • Oncology

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