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Title: Chemosensitivity of primary human fibroblasts with defective unhooking of DNA interstrand cross-links

Xeroderma pigmentosum (XP) is characterised by defects in nucleotide excision repair, ultraviolet (UV) radiation sensitivity and increased skin carcinoma. Compared to other complementation groups, XP-F patients show relatively mild cutaneous symptoms. DNA interstrand cross-linking agents are a highly cytotoxic class of DNA damage induced by common cancer chemotherapeutics such as cisplatin and nitrogen mustards. Although the XPF-ERCC1 structure-specific endonuclease is required for the repair of ICLs cellular sensitivity of primary human XP-F cells has not been established. In clonogenic survival assays, primary fibroblasts from XP-F patients were moderately sensitive to both UVC and HN2 compared to normal cells (2- to 3-fold and 3- to 5-fold, respectively). XP-A fibroblasts were considerably more sensitive to UVC (10- to 12-fold) but not sensitive to HN2. The sensitivity of XP-F fibroblasts to HN2 correlated with the defective incision or 'unhooking' step of ICL repair. Using the comet assay, XP-F cells exhibited only 20% residual unhooking activity over 24 h. Over the same time, normal and XP-A cells unhooked greater than 95% and 62% of ICLs, respectively. After HN2 treatment, ICL-associated DNA double-strand breaks (DSBs) are detected by pulse field gel electrophoresis in dividing cells. Induction and repair of DNA DSBs was normal in XP-Fmore » fibroblasts. These findings demonstrate that in primary human fibroblasts, XPF is required for the unhooking of ICLs and not for the induction or repair of ICL-associated DNA DSBs induced by HN2. In terms of cancer chemotherapy, people with mild DNA repair defects affecting ICL repair may be more prevalent in the general population than expected. Since cellular sensitivity of primary human fibroblasts usually reflects clinical sensitivity such patients with cancer would be at risk of increased toxicity.« less
Authors:
 [1] ;  [2] ;  [3] ;  [2]
  1. Cancer Research UK Drug-DNA Interactions Research Group, Department of Oncology, Royal Free and University College Medical School, 91 Riding House Street, London, W1W 7BS (United Kingdom). E-mail: p.clingen@ucl.ac.uk
  2. Brunel Institute for Cancer Genetics and Pharmacogenomics, Division of Biosciences, School of Health Sciences and Social Care, Brunel University, Middlesex, UB8 3PH (United Kingdom)
  3. Cancer Research UK Drug-DNA Interactions Research Group, Department of Oncology, Royal Free and University College Medical School, 91 Riding House Street, London, W1W 7BS (United Kingdom)
Publication Date:
OSTI Identifier:
20972122
Resource Type:
Journal Article
Resource Relation:
Journal Name: Experimental Cell Research; Journal Volume: 313; Journal Issue: 4; Other Information: DOI: 10.1016/j.yexcr.2006.11.007; PII: S0014-4827(06)00481-2; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
63 RADIATION, THERMAL, AND OTHER ENVIRONMENTAL POLLUTANT EFFECTS ON LIVING ORGANISMS AND BIOLOGICAL MATERIALS; CARCINOMAS; CHEMOTHERAPY; CONGENITAL DISEASES; DNA; EXCISION REPAIR; FIBROBLASTS; HEREDITARY DISEASES; SENSITIVITY; SKIN DISEASES; STRAND BREAKS; ULTRAVIOLET RADIATION