Influence of GSTM1 null and low repair XPC PAT+ on anti-B[a]PDE-DNA adduct in mononuclear white blood cells of subjects low exposed to PAHs through smoking and diet.

The influence of low-activity NER genotypes (XPC PAT-/+, XPA-A23G, XPD Asp312Asn, XPD Lys751Gln) and GSTM1 (active or null) was evaluated on anti-benzo[a]pyrene diol epoxide-(B[a]PDE)-DNA adduct formed in the lymphocyte plus monocyte fraction (LMF). The sample population consisted of 291 healthy subjects with low exposure to polycyclic aromatic hydrocarbons (PAHs) (B[a]P) through their smoking (n=126 smokers) or dietary habits (n=165 non-smokers with high (>or=52 times/year) consumption of charcoaled meat or pizza). The bulky anti-B[a]PDE-DNA adduct levels were detected by HPLC/fluorescence analysis and genotypes by PCR. Anti-B[a]PDE-DNA was present (>or=0.5 adducts/10(8) nucleotides) in 163 (56%) subjects (median (range) 0.77 (0.125-32.0) adducts/10(8) nucleotides), with smokers showing a significantly higher adduct level than non-smokers with high consumption of PAH-rich meals (P<0.01). Our exposed-sample population with unfavourable XPC PAT+/- or +/+ and GSTM1 null genotypes has the significantly highest adduct level (P<0.01). Taking into account tobacco smoke and diet as sources of exposure to B[a]P, low-activity XPC PAT+ shows a major role in smokers (P<0.05) and GSTM1 null in non-smokers with frequent consumption of PAH-rich meals (P<0.01). The modulation of anti-B[a]PDE-DNA adduct in the LMF by GSTM1 null and low-activity XPC PAT+ polymorphisms may be considered as potential genetic susceptibility factors that can modify individual responses to low PAH (B[a]P) genotoxic exposure, with the consequent risk of cancer in the general population.