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Common Polymorphisms in DNA Repair Genes Associated with Increased Polycyclic Aromatic Hydrocarbon-DNA Adduct Formation in Human Sperm

Guixiang ji Key Laboratory of Reproductive Medicine;Institute of Toxicology;Nanjing Medical University;140 Hanzhong Road;Nanjing 210029;China.

  Objectives:Nucleotide excision repair(NER) and base excision repair(BER) are the primary mechanisms for repair of bulky adducts caused by chemical agents,such as PAHs.It is expected that genetic polymorphisms in NER or BER genes may modulate individual susceptibility to PAHs exposure.We evaluated the effects of PAHs exposure and functional genetic polymorphisms in NER and BER pathway,alone or combined,on polycyclic aromatic hydrocarbon-DNA(PAH-DNA) adducts in human sperm. Methods:465 patients diagnosed with unexplained male factor infertility were included in this study. PAH-DNA adducts were measured by an indirect immunofluorescence method using BPDE-DNA(5D11) monoclonal antibody with FITC-conjugated secondary antibody.The intensity of FITC fluorescence was then detected by the FACSCalibur flow cytometer.To assess the reliability and efficiency of flow cytometry,46 semen samples were analyzed simultaneously with fluorescence microscopy and flow cytometry.We used the polymerase chain reaction(PCR) and restriction fragment length polymorphism (RFLP) to genotype the following SNPs:XRCC1 5 UTR -T/C(rs3213245),XRCC1 Argl94Trp (rsl799782),XRCC1 Arg280His(rs25489),XRCC1 Arg399Gln(rs25487),XPA 5 UTR -C/T(rsl800975), XPD Asp312Asn(rs 1799793),ERCC1 3 UTR G/T(rs3212986),and XPF Ser835Ser(rsl799801).PAHs exposure was indicated by urinary 1-hydroxypyrene(1-OHP) level,and determined by LC-MS/MS. Results:A good correlation is detected in the results as measured by flow cytometry and fluorescence microscopy(r = 0.88,P<0.001).A positive correlation between sperm PAH-DNA adducts and the urinary 1-OHP levels was found(r = 0.262,P = 0.003),and the habitual consumption of charcoaled food was significantly associated with an enhancement of adduct levels.In multivariate models adjusted for potential confounders,we observed significant associations between XRCC1 5 UTR -T/C,XRCC1 Argl94Trp,Arg399Gln polymorphisms and sperm adduct levels.Moreover,when the patients were dichotomized by urinary 1-hydroxypyrene(1-OHP) levels,the adverse effects of XRCC1 Argl94Trp, Arg399Gln polymorphisms on PAH-DNA adducts were detected only in the high-exposure group. Conclusions:This is the first epidemiologic study to explore the effects of PAHs exposure at general population levels and DNA repair polymorphism,alone or combined,on sperm PAH-DNA adducts.Our findings provided the first evidence polymorphisms of XRCC1 may modify sperm PAH-DNA adduct levels and may be useful biomarkers to identify individuals susceptible to DNA damage resulting from PAHs exposure.A more comprehensive genetic approach in a larger study population is valuable for further studies.……