title: Monitoring the (photo)genotoxicity of photosensitizer drugs: direct quantitation of single-strand breaks in deoxyribonucleic acid using an oligonucleotide chip.
abstract: Oligonucleotide chip-based assays can be a sample-thrifty, time-saving, routine tool for evaluation of chemical-induced DNA strand breaks. This article describes a novel approach using an oligonucleotide chip to determine photosensitizer-induced DNA single-strand breaks. Surface coverage of fluorophore-labeled oligonucleotides on silicon dioxide chip surfaces was determined on alkaline phosphatase digestion. Fluorescence maxima (at 520 nm) of the solutions were converted to molar concentrations of the fluorescein-modified oligonucleotide by interpolation from a predetermined standard linear calibration curve. The photosensitizing activity of chlorpromazine and triflupromazine toward DNA single-strand breaks was then studied at different drug doses and also as a function of photoirradiation time. Photoinduced single-strand breaks calculated using the method described here agreed with values predicted by theoretical extrapolation of the single-strand breaks obtained for plasmid DNAs from agarose gel electrophoresis, and thereby indirectly validated the chip-based assays. Under UV irradiation (>or=93.6 kJ/m2) chlorpromazine (>or=0.08 mM) was found to have significant photogenotoxicity. However, triflupromazine did not exhibit any (photo)genotoxicity over the concentration range studied (0.04-0.20mM). The method developed will be useful for quantitative screening of drug genotoxicity in terms of induction of breaks in DNA.
authors.affiliation: Research Institute of Pharmaceutical Sciences and College of Pharmacy, Seoul National University, 599 Gwanangno, Gwanak-gu, Seoul, Republic of Korea.
authors.forename: Min Jung
authors.initials: MJ
authors.lastname: Kim
authors.forename: Sukdeb
authors.initials: S
authors.lastname: Pal
authors.forename: Pravin K
authors.initials: PK
authors.lastname: Naoghare
authors.forename: Joon Myong
authors.initials: JM
authors.lastname: Song
mesh_terms: D001483:Base Sequence; D002746:Chlorpromazine / Q000633:toxicity; D004247:DNA / Q000235:genetics / Q000378:metabolism*; D053904:DNA Breaks, Single-Stranded / Q000187:drug effects* / Q000528:radiation effects; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D009153:Mutagens / Q000633:toxicity*; D020411:Oligonucleotide Array Sequence Analysis; D017319:Photosensitizing Agents / Q000633:toxicity*; D013499:Surface Properties; D013997:Time Factors; D014273:Triflupromazine / Q000633:toxicity; D014466:Ultraviolet Rays
chemical_list: D009153:Mutagens; D017319:Photosensitizing Agents; D004247:DNA; D014273:Triflupromazine; D002746:Chlorpromazine