title: Preferential binding of cisplatin to mitochondrial DNA of Chinese hamster ovary cells.
abstract: Some chemical carcinogens localize preferentially in mitochondrial DNA (mtDNA) when compared with genomic DNA (gDNA). Here we compare the ability of cisplatin (cis-diamminedichloroplatinum[II]) to induce DNA adducts in both genomic and mtDNA of Chinese hamster ovary (CHO) cells in culture. Cytotoxicity was examined by cell survival 4, 8 and 24 h after exposure to 50 microM cisplatin. Cisplatin-DNA adducts were measured in DNA from nuclear and mitochondrial fractions by dissociation-enhanced lanthanide fluoroimmunoassay (DELFIA), a sensitive competitive microtiter-based immunoassay utilizing antiserum elicited against cisplatin-modified DNA. An additional comparison of cisplatin-DNA binding in both compartments was performed by immunoelectron microscopy using the cisplatin-DNA antiserum and colloidal gold. DELFIA analysis of cisplatin-DNA adducts in gDNA and mtDNA showed a six-fold higher incorporation of drug into mtDNA as compared to gDNA. Morphometric studies of colloidal gold distribution in photomicrographs of CHO cells showed mtDNA to contain a four-fold higher concentration of cisplatin as compared to nuclear DNA. Therefore, both methods demonstrated a preferential binding of cisplatin to mtDNA versus gDNA.
authors.affiliation: Laboratory of Cellular Carcinogenesis and Tumor Promotion, NIH, National Cancer Institute, Bethesda, MD 20892, USA.
authors.forename: O A
authors.initials: OA
authors.lastname: Olivero
authors.forename: C
authors.initials: C
authors.lastname: Semino
authors.forename: A
authors.initials: A
authors.lastname: Kassim
authors.forename: D M
authors.initials: DM
authors.lastname: Lopez-Larraza
authors.forename: M C
authors.initials: MC
authors.lastname: Poirier
mesh_terms: D000818:Animals; D016466:CHO Cells; D002467:Cell Nucleus / Q000235:genetics / Q000648:ultrastructure; D002945:Cisplatin / Q000378:metabolism* / Q000633:toxicity; D006224:Cricetinae; D018736:DNA Adducts; D004272:DNA, Mitochondrial / Q000378:metabolism*; D015200:Fluoroimmunoassay; D016678:Genome; D016253:Microscopy, Immunoelectron; D008928:Mitochondria / Q000235:genetics / Q000648:ultrastructure
chemical_list: D018736:DNA Adducts; D004272:DNA, Mitochondrial; D002945:Cisplatin