Sex differences in lung CYP1A1 expression and DNA adduct levels among lungcancer patients

Several epidemiological studies have indicated that female tobacco smokers may be at higher risk of lung cancer than males, In a study of lung cancer cases, we have found that female smokers had a significantly higher level o f aromatic/hydrophobic DNA adducts in their nontumor lung tissue (15.39 +/- 9.47 adducts/10(8) nucleotides, n = 29) than male smokers (12.08 +/- 8.14, n = 93; P = 0.047). Females had significantly higher levels of adducts/pac k-year (females 0.95 +/- 0.82 adducts/pack-year and males 0.46 +/- 0.46; P = 0.0004) and adducts/cigarette/day (females 1.48 +/- 1.29 and males 0.89 /- 0.74, P = 0.015). By quantitative reverse transcription-PCR, it was foun d that female smokers exhibited a significantly higher expression Level of Lung CYP1A1 (494 +/- 334 CYP1A1 mRNA/10(6) glyceraldehyde-3-phophate dehydr ogenase mRNA, n = 15) compared with males (210 +/- 208, n = 12; P = 0.016). Furthermore, for both sexes combined a significant correlation between CYP 1A1 expression and DNA adduct level was found (r = 0.50, P = 0.009), In con clusion, the observed sex difference in aromatic/hydrophobic DNA adduct lev els may at least in part be explained by different Levels of CYP1A1 express ion.