Metabolic activation, DNA adducts, and H-ras mutations in human neoplastic and non-neoplastic laryngeal tissue.
Metabolic activation, DNA adducts, and H-ras mutations were examined in human laryngeal tissue (n = 16) from both smoker and non/ex-smoker patients with laryngeal cancer. DNA adducts detected by 32P-postlabelling were evident only in smokers (n = 13); in fact, smoking cessation for as little as 10 months resulted in no DNA adducts detected (n = 3). Total DNA adduct levels in these samples were significantly correlated with levels of cytochromes P-4502C and 1A1 in laryngeal microsomes. Moreover, the P-4501A1 levels represent the highest yet found in human tissues. In contrast, laryngeal microsomes did not have detectable P-4501A2 activity, while laryngeal cytosols showed appreciable N-acetyltransferase activity for p-aminobenzoic acid (NAT1) but not sulfamethazine (NAT2). DNA was extracted from laryngeal specimens and amplified by PCR. Nylon filter dot or slot blots were hybridized with 32P-labelled probes for codons 12, 13, and 61 of the H-ras gene. Sixty percent of specimens demonstrated mutations in either codon 12, 13, or 61; a single common and specific mutation was a Gln-->Glu transversion in codon 61. This mutation appeared in 5 laryngeal specimens, all from smokers. These results implicate cigarette smoke components, bioactivated by CYP1A1 and/or CYP2C, in DNA adduct formation. These results also demonstrate a probable smoking-related H-ras Gln-->Glu transversion in codon 61.
Stern
S J
SJ
University of Arkansas for Medical Sciences, Department of Otolaryngology--Head and Neck Surgery, Little Rock 72205.
Degawa
M
M
Martin
M V
MV
Guengerich
F P
FP
Kaderlik
R K
RK
Ilett
K F
KF
Breau
R
R
McGhee
M
M
Montague
D
D
Lyn-Cook
B
B
D010129:4-Aminobenzoic Acid / Q000378:metabolism; D001564:Benzo(a)pyrene / Q000378:metabolism; D001711:Biotransformation; D004249:DNA Damage; D004273:DNA, Neoplasm / Q000235:genetics; D011905:Genes, ras; D006801:Humans; D007822:Laryngeal Neoplasms / Q000235:genetics / Q000378:metabolism*; D007830:Larynx / Q000378:metabolism*; D015394:Molecular Structure; D009154:Mutation; D009284:Naphthols / Q000378:metabolism; D012907:Smoking / Q000378:metabolism; D013418:Sulfamethazine / Q000378:metabolism; D015238:Sulfotransferases / Q000378:metabolism
D004273:DNA, Neoplasm; D009284:Naphthols; C029350:1-naphthol; D001564:Benzo(a)pyrene; D013418:Sulfamethazine; D015238:Sulfotransferases; D010129:4-Aminobenzoic Acid