Deficient base excision repair of oxidative DNA damage induced by methylene blue plus visible light in xeroderma pigmentosum group C fibroblasts

Biochem Biophys Res Commun. 2007 Aug 10;359(4):1004-9. doi: 10.1016/j.bbrc.2007.06.005. Epub 2007 Jun 8.


Methylene blue plus visible light (MB+VL) results in oxidative DNA damage, producing predominantly 7,8-dihydroxy-8-oxoguanine and other single base modifications that are repaired by base excision repair (BER). AdCA17 is non-replicating recombinant human adenovirus that infects human cells and expresses the beta-galactosidase (beta-gal) reporter gene. We have examined host cell reactivation (HCR) of beta-gal activity for (MB+VL)-treated AdCA17 in cells from patients with xeoroderma pigmentosum from complementation group C (XP-C). HCR was substantially reduced in an SV40 transformed XP-C fibroblast compared to two SV40-transformed normal cells and in three XP-C primary fibroblast strains compared to four normal strains for both untreated and UVC-treated cells. These results indicate an involvement of the XPC gene in BER of MB+VL-induced oxidative DNA damage. In addition, pre-UVC-treatment of both normal and XP-C fibroblasts resulted in enhanced HCR of the MB+VL-treated reporter gene giving evidence for a UVC-inducible and XPC-independent BER pathway in human cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cells, Cultured
  • DNA Damage*
  • DNA Repair / drug effects*
  • DNA Repair / radiation effects*
  • Fibroblasts / drug effects*
  • Fibroblasts / radiation effects*
  • Humans
  • Light
  • Methylene Blue / administration & dosage*
  • Oxidative Stress / drug effects*
  • Oxidative Stress / radiation effects*
  • Xeroderma Pigmentosum / genetics*
  • Xeroderma Pigmentosum / pathology*


  • Methylene Blue