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.
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.
Escobar
Patricia A
PA
Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
Olivero
Ofelia A
OA
Wade
Nancy A
NA
Abrams
Elaine J
EJ
Nesel
Carol J
CJ
Ness
Roberta B
RB
Day
Richard D
RD
Day
Billy W
BW
Meng
Quanxin
Q
O'Neill
J Patrick
JP
Walker
Dale M
DM
Poirier
Miriam C
MC
Walker
Vernon E
VE
Bigbee
William L
WL
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*
D019380:Anti-HIV Agents; D004338:Drug Combinations; D006021:Glycophorins; D018894:Reverse Transcriptase Inhibitors; D019259:Lamivudine; D015215:Zidovudine