Sign up for Table of Contents Alerts.
Email this page
Print this page
Brief Communication
Gene-Specific Selection Against Experimental Fanconi Anemia Gene Inactivation in Human Cancer
Eike Gallmeier, Tomas Hucl, Eric S. Calhoun, Steven C. Cunningham, Fred Bunz, Jonathan R. Brody and Scott E. Kern
volume 6 | issue 5
May 2007Pages: 654 - 660
We now provide open access to journal articles published online for one year or more. This article may be downloaded at the following link:
Download PDFIf the document does not open, please right-click on the link (control-click on a Macintosh) and select the option to save the file to disk.
The Fanconi anemia (FA) gene family comprises at least 12 genes interacting in a common pathway involved in DNA repair. To gain insight into the role of FA gene inactivation occurring in tumors among the general population, we endogenously targeted in cancer cells four FA genes that act at different stages of the FA pathway. After successful mono-allelic deletion of all genes, the sequential homozygous deletion was achieved only for FANCC and FANCG, acting upstream, but not for BRCA2 or FANCD2, acting downstream in the FA path¬way. Targeting of the second allele in BRCA2 and FANCD2 heterozygote clones resulted in re-deletion exclusively of the already defective allele in multiple instances (13x concerning BRCA2, 25x concerning FANCD2), strongly suggesting a detrimental phenotype. Unlike com¬plete FANCD2 disruption, the mere reduction of FANCD2 protein levels had no discernible effect. In addition, we confirmed that human cancer cells harboring the Seckel ATR mutation display impaired FANCD2 monoubiquitination and FANCD2 nuclear focus formation, as well as an increased sensitivity to DNA interstrand-crosslinking agents. Nevertheless, these cells were viable, indicating an ATR-independent function of FANCD2, distinct from its major known functions, to be responsible for the detrimental effects of FANCD2 loss. In conclusion, we established the downstream FA genes FANCD2 and BRCA2 to represent particularly vulnerable parts of the FA pathway, providing direct evidence for the paradoxical assumption that their inactivation could be predominantly selected against in cancer cells. This would explain why certain FA gene defects, despite an apparent selection for FA pathway inactivation in cancer, are rarely observed in tumors among the general population.
Authors
Eike Gallmeier
The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins University, Baltimore, MD
Tomas Hucl
The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins University, Baltimore, MD
Eric S. Calhoun
The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins University, Baltimore, MD
Steven C. Cunningham
The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins University, Baltimore, MD
Fred Bunz
Johns Hopkins University School of Medicine; Baltimore, Maryland USA
Jonathan R. Brody
Thomas Jefferson University, Philadelphia, PA
Scott E. Kern
The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins University, Baltimore, MD
We now provide open access to journal articles published online for one year or more. This article may be downloaded at the following link:
Download PDFIf the document does not open, please right-click on the link (control-click on a Macintosh) and select the option to save the file to disk.