title: Genotoxicity assessed by the comet and GPA assays following in vitro exposure of human lymphoblastoid cells (H9) or perinatal exposure of mother-child pairs to AZT or AZT-3TC.
abstract: The genotoxicity of zidovudine (AZT) based treatments was investigated in human H9 lymphoblastoid cells in an in vitro study and in red blood cells (RBCs) from perinatally exposed HIV-1-infected mothers and their infants in an observational cohort study. Exposure of H9 cells for 24 hr to AZT produced dose-dependent increases in Comet assay tail moment (TM) when electrophoresed at pH 13.0, but not at pH 12.1 or pH 8.0, suggesting that DNA damage was via alkali-labile lesions and not double-stranded DNA strand breaks. The TM dose response at pH 13.0 correlated directly with AZT-DNA incorporation determined by AZT-radioimmunoassay. Levels of DNA damage in utero, measured by Comet assay TM, were similar in cord blood mononuclear cells of nucleoside analog-exposed newborns (n = 43) and unexposed controls (n = 40). In contrast, the glycophorin A (GPA) somatic cell mutation assay (which screens for large-scale DNA damage in RBCs) showed clear evidence that GPA N/N variants, arising from chromosome loss and duplication, somatic recombination, and gene conversion, were significantly elevated in mother-child pairs receiving prepartum AZT plus lamivudine (3TC). Cord blood from newborns exposed to AZT-3TC had GPA N/N variant frequencies of 4.7 +/- 0.7 (mean +/- SE) x 10(-6) RBCs (n = 26 infants) compared with 2.2 +/- 0.3 x 10(-6) RBCs for unexposed controls (n = 30 infants; P < 0.001). Elevations in GPA N/N variants generally persisted through 1 year of age in nucleoside analog-exposed children. Overall, the mutagenic effects found in mother-child pairs receiving AZT-based treatments justify their surveillance for long-term genotoxic consequences.
authors.affiliation: Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Escobar
authors.forename: Ofelia A
authors.initials: OA
authors.lastname: Olivero
authors.forename: Nancy A
authors.initials: NA
authors.lastname: Wade
authors.forename: Elaine J
authors.initials: EJ
authors.lastname: Abrams
authors.forename: Carol J
authors.initials: CJ
authors.lastname: Nesel
authors.forename: Roberta B
authors.initials: RB
authors.lastname: Ness
authors.forename: Richard D
authors.initials: RD
authors.lastname: Day
authors.forename: Billy W
authors.initials: BW
authors.lastname: Day
authors.forename: Quanxin
authors.initials: Q
authors.lastname: Meng
authors.forename: J Patrick
authors.initials: JP
authors.lastname: O'Neill
authors.forename: Dale M
authors.initials: DM
authors.lastname: Walker
authors.forename: Miriam C
authors.initials: MC
authors.lastname: Poirier
authors.forename: Vernon E
authors.initials: VE
authors.lastname: Walker
authors.forename: William L
authors.initials: WL
authors.lastname: Bigbee
mesh_terms: D019380:Anti-HIV Agents / Q000008:administration & dosage / Q000627:therapeutic use / Q000633:toxicity*; D002460:Cell Line; D020552:Comet Assay; D004338:Drug Combinations; D004912:Erythrocytes / Q000187:drug effects; D005260:Female; D006021:Glycophorins / Q000235:genetics; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D019259:Lamivudine / Q000008:administration & dosage / Q000627:therapeutic use / Q000633:toxicity*; D007962:Leukocytes / Q000187:drug effects; D008431:Maternal-Fetal Exchange; D009152:Mutagenicity Tests; D009154:Mutation; D011247:Pregnancy; D018894:Reverse Transcriptase Inhibitors / Q000008:administration & dosage / Q000627:therapeutic use / Q000633:toxicity*; D015215:Zidovudine / Q000008:administration & dosage / Q000627:therapeutic use / Q000633:toxicity*
chemical_list: D019380:Anti-HIV Agents; D004338:Drug Combinations; D006021:Glycophorins; D018894:Reverse Transcriptase Inhibitors; D019259:Lamivudine; D015215:Zidovudine