Tohoku J. Exp. Med., 2010, 221(1)

Fanconi Anemia Is Characterized by Delayed Repair Kinetics of DNA Double-Strand Breaks

ANDREJA LESKOVAC,¹ DRAGANA VUJIC,² MARIJA GUC-SCEKIC,² SANDRA PETROVIC,¹ IVANA JOKSIC,¹ PREDRAG SLIJEPCEVIC³ and GORDANA JOKSIC¹

¹Vinca Institute of Nuclear Sciences, Belgrade, Serbia
²Mother and Child Health Care Institute of Serbia, Belgrade, Serbia
³Brunel Institute of Cancer Genetics & Pharmacogenomics, Brunel University, Uxbridge, Middlesex, UK

Among patients with bone marrow failure (BMF) syndrome, some are happened to have underlying Fanconi anemia (FA), a genetically heterogeneous disease, which is characterized by progressive pancytopenia and cancer susceptibility. Due to heterogeneous nature of the disease, a single genetic test, as in vitro response to DNA cross-linking agents, usually is not enough to make correct diagnosis. The aim of this study was to evaluate whether measuring repair kinetics of radiation-induced DNA double-strand breaks (DSBs) can distinguish Fanconi anemia from other BMF patients. An early step in repair of DSBs is phosphorylation of the histone H2AX, generating γ-H2AX histone, which extends over mega base-pair regions of DNA from the break site and is visualised as foci (γ-H2AX foci) with specific antibodies. The primary fibroblasts, established from FA patients, were exposed to γ-rays, a dose of 2 Gy (⁶⁰Co), incubated for up to 24 hours under repair-permissive conditions, and assayed for the level of γ-H2AX foci and apoptosis at different recovery times after the treatment. Cell lines originating from FA patients displayed a significant delay in the repair of radiation-induced DNA DSBs relative to non-FA bone marrow failure (non-FA BMF) and control cell lines. The delay is especially evident at recovery time of 24 hours, and is seen as about 8-fold increase of residual γ-H2AX foci compared to self-state before irradiation. The delay in repair kinetics of FA cells represents the unique feature of FA cellular phenotype, which should be exploited to distinguish FA cellular phenotype.

keywords —— double-strand breaks; repair kinetics; γ-H2AX foci; apoptosis; irradiation

© 2010 Tohoku University Medical Press

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Tohoku J. Exp. Med., 2010, 221, 69-76

Correspondence: Gordana Joksic, Vinca Institute of Nuclear Sciences, Mike Petrovica Alasa 12-14, 11 000 Belgrade, Serbia.

e-mail: gjoksic@vinca.rs