Accumulation and persistence of DNA adducts of the synthetic steroid cyproterone acetate in rat liver

Cyproterone acetate (CPA) is a synthetic steroid which is widelyused in antlandrogenic and gestagenic drugs. We have recentlyshown that CPA induces DNA adducts in cultured rat hepatocytesand in rat liver (1). In the present investigation, we studiedthe persistence and accumulation of CPA-derived DNA adductsin the liver of rats using the 32 technique. To study the persistenceof CPA-DNA adducts, rats were treated with a single oral doseof 10 (female rats) or 100 mg CPA/kg body wt (male rats). FourDNA adducts were detected in the liver of both gender. In femalerats, maximal total DNA adduct levels of 3.40±0.04 adducts/10⁶nucleotides were observed after 1 week. Eleven weeks later,40% of the adducts determined after 1 week were still detectable.In male rats, maximal hepatic DNA adduct levels of     

DNA adducts caused by tamoxifen and toremifene in human microsomal system and lymphocytes in vitro

DNA-binding of tamoxifen and toremifene was studied in rat invivo, in human and rat microsomes in vitro, and in culturedprimary human lymphocytes by ³²P-postlabelling. Only tamoxifencaused DNA adducts in rat liver. Both compounds induced adductsin both rat and human micro-somal systems and in cultured lymphocytes.The levels of adducts in microsomes and lymphocytes were low,ca. 1 adduct/10⁹ nucleotides. Toremifene showed lower bindingin each system, and in lymhocytes adducts were only detectedat a cytotoxic dose level.     

SHORT COMMUNICATION: Detection of DNA adducts in the white blood cells of B6C3F1 mice treated with benzene

We have employed the P₁-enhanced ³²P-postlabeling procedureto detect the formation DNA of adducts in the white blood cells(WBC) of B6C3F1 mice treated by i.p. injection with benzene.Treatment twice a day with 440 mg/kg benzene for 1–7 daysresulted in the formation of one major (adduct 1) and one minor(adduct 2) DNA adduct in the WBCs of mice. The same DNA adductpattern was also found in the bone marrow (BM) of benzene treatedmice. The relative adduct levels were dependent upon both benzenedose from 100–440 mg/kg and treatment time from 1 to 7days. The relative adduct levels ranged between 0.11 and 1.33adducts in 10⁷ nucleotides for WBCs and 0.16–1.21 adductsin 107 nucleotides for BM. Following treatment with benzene,the levels of DNA adducts formed in WBCs were significantlycorrelated with the levels of DNA adducts formed in BM (r² =0.97, P <0.001). Our results suggest that measurement ofDNA adducts in WBCs may be an indicator of DNA adduct formationin BM following BZ exposure.     

32P-HPLC suitable for characterization of DNA adducts formed in vitro by polycyclic aromatic hydrocarbons and derivatives

Analysis of DNA adducts demands both high sensitivity and goodresolution. A high-performance liquid chromato-graphy methodfor ³²P-postlabeled DNA adducts (³²P-HPLC) was used to investigateDNA adduct formation from 38 polycyclic hydrocarbons and biphenylsin vitro. The ³²P-HPLC method proved to be useful for separation,detection and characterization of DNA adducts from most of thesubstances. The in vitro method used to form the DNA adducts,with calf thymus DNA, nucleotide 3'-phosphates and metabolicactivation through S-9 liver homo-genate, gave poor quantitativereproducibility. However, the results showed that the ³²P-HPLCmethod was suitable for characterizing DNA adducts from manysubstances. From 35 of the tested substances 365 DNA and nucleotide3'-phospate adducts were detected and characterized concerningretention times. Of the adducts, 171 were detected in DNA and39 of them from five substances were characterized concerningtarget nucleotides. The retention time library built can beused in future analyses of DNA with complex patterns of DNAadducts.     

SHORT COMMUNICATION: Cyproterone acetate is an integral part of hepatic DNA adducts induced by this steroidal drug

We have recently shown that cyproterone acetate (CPA), an activecomponent of some antiandrogenic drugs, induces the formationof DNA adducts detectable by the ³²P-DNA postlabelling techniquein rat liver. The postlabelling technique, however, does notprovide evidence for the chemical nature of the adducts observed.To ascertain whether the CPA-induced adducts do contain CPA,we have incubated tritiated CPA with cultured hepatocytes fromfemale rats, digested the DNA to 3'-monophospho-nucleosides,extracted the DNA adducts formed into but-anol and phosphorylatedthe adducts in the extract with unlabelled ATP. One major andone minor ³H-labelled adduct spot were detectable on the TLCchromatograms. The spots appeared at positions identical tothose observed in the ³²P-postlabelling experiments with unlabelledCPA. Furthermore, the ratio of ³H activity for the major versusthe minor adduct spot was 11.9±1.8, which agreed withthe corresponding ratio for the ³²P activities, which was 13.2±3.5.These findings indicate that the CPA-induced DNA adducts, whichwe have previously detected by ³²P-postlabelling do containCPA or CPA metabolites.     

32P-Postlabelling determination of DNA adducts of malonadlehyde in humans: total white blood cells and breast tissue

DNA adducts of malonaldehyde (MA) were measured in total whiteblood cells (TWBC) fo healthy individuals from both sexes anddifferent ages, as well as in breast tissue (BT) samples obtainedfrom, healthy females undergoing reduction mammaplasty. A largeinterindividual variation in adduct levels was observed. Theaverage adduct level found in TWBC, considering both sexes andall ages was 2.6 ± 1.2 adducts/10⁷ nucleotides (n = 26).A similar average DNA adduct concetratioon was found in BT andamounted to 3.0 ± 1.3 (n = 7) adducts/10⁷ nucleotides.Our results whow that DNA adducts of MA can be measured in humansusing ³²P-postlabelling in combination with nucleas P1 and reversed-phaseHPLC as adduct enrichment procedures, and furher validate theseadducts as suitable biomarkers for the measurement of DNA damageinflicted by endogenously induced oxidative processes such aslipd peroxidation.     

The measurement of cisplatin-DNA adduct levels in testicular cancer patients

Seventeen patients with ‘poor prognosis’ non-seminomatoustesticular cancer were monitored for formation of intrastrandbidentate N⁷-d(ApG)- and N⁷-d(GpG)- diammineplatinum adductsin peripheral blood cell DNA during the course of cisplatin-basedchemotheraphy. Adduct values from blood cell DNA samples werecompared with disease response data from the same individuals.Patients who received a dose of 40 mg/m² cisplatin for 5 daysgenerally formed more adducts than patients receiving 20 mg/m²for 5 days, and adduct levels ranged from 0 to approximately300 amol/µg DNA. Among the individuals who achieved acomplete response, the median adduct level was 170 amol/µgDNA and the mean was 162. Among the individuals who achieveda partial response, the median adduct level was 78 amol/ µgDNA and the mean was 83. Comparison of adduct levels betweenresponse groups using the Mann-Whitney test gave a two-sidedP value of 0.072 (one-sided P value 0.036). Of 11 patients forminghigh levels of adduct (>140 amol/µg DNA), 10 achieveda complete response; this compares with two complete respondersin the group of six patients forming low levels (<100 amol/µg DNA) of adduct (P = 0.055, two-sided Fisher exact test).We conclude that cisplatin-DNA adduct formation in peripheralblood cell DNA correlates with the occurrence of complete responsein patients with poor prognosis testicular cancer.     

DNA adduct formation by tamoxifen with rat and human liver microsomal activation systems

Using microsomal preparations from rat and human liver, we investigatedthe activation of the anti-estrogen compound tamoxifen (TMX)to form DNA adducts. Pretreatment of rats with phenobarbitalincreased DNA adduct formation by microsomal activation of TMX3- to 6-fold, depending on the cofactors used. When reducednicotinamide-adenine dinucleotide phosphate (NADPH) was usedas a cofactor in human and rat microsomal activation systems,the relative DNA adduct levels were 2.9 and 5.2 x 10^–8respectively and 1-3 TMX-DNA adducts were detected by ²³P-postlabeling;DNA adduct 1 was the same in both microsomal systems. When cumenehydroperoxide (CuOOH) was used as a cofactor, activation ofTMX produced four major DNA adducts and several minor DNA adductsin both rat and human liver microsomes; the relative adductlevels were 11.1 and 23.1 xlO^–8 respectively. TMX-DNAadducts 1, 4, 5 and 6 were similar in both human and rat microsomalsystems with CuOOH as the cofactor. The TMX-DNA adducts formedwith NADPH as the cofactor were clearly different from thoseformed with CuOOH as the cofactor, which implies that the metabolitesleading to the individual DNA adducts were different. Additionof a P450 inhibitor, either n-octylamine or     

DNA adduct formation, cell proliferation and aberrant crypt focus formation induced by PhIP in male and female rat colon with relevance to carcinogenesis

2-Amino-1-methyl-6-phenylimidazo[4, 5-b]pyridine (PhIP) inducescolon tumors in male, but not female, F344 rats, We investigatedthe mechanisms leading to this difference by measuring the levelof PhlP-DNA adducts, the enhancement of cell proliferation andaberrant crypt focus (ACF) formation in colon mucosa. PhIP wasadministered in the diet at a level of 0.04% to both male andfemale F344 rats for 1–8 weeks. The level of DNA adductsin the colon mucosa was measured using the ³²P-postlabelingmethod. Four major PhlP-DNA adducts were detected in fairlyconstant proportions in all the animals examined. The levelof PhlP-DNA adducts in male and female rats was the same, indicatingno direct correlation between adduct levels and carcinogenesis.Labeling indices (LIs) were determined by measuring BrdU incorporationin rats after feeding with a PhIP diet for 4, 8 and 12 weeks.After 8 weeks administration the LI had increased 1.5-fold inthe colon of the male rats, but no increase was observed inthe female rats. ACF formation was examined after feeding witha PhIP diet for 14 weeks. The number of aberrant crypt fociwas 6.6 ± 1.5 per rat in males and 1.9 ± 0.5 perrat in females. Thus differences in colon tumor developmentin male and female rats takes place at an early stage(s). Ourresults suggest that, in addition to DNA adduct formation, enhancedproliferation contribites to the formation of ACFs, which arepremalignant lesions of the colon.     

Validation in rats of two biomarkers of exposure to the food-borne carcinogen 2-amino-1-methyl-6-phenylimidazo[4, 5-b]pyridine (PhIP): PhIP-DNA adducts and urinary PhIP

2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP)-DNA adductsin white blood cells and tissues and unmetab-olized PhIP inurine were validated as biomarkers of exposure in male Fischer-344rats treated with daily PhIP doses ranging from 1 to 0.0001mg/kg. At the end of the 23 day treatment period all rats werekilled and their blood and 10 tissues were collected for isolationof DNA and analysis of PhIP-DNA adducts by ³²P-postlabelingand alkaline hydrolysis with GC/MS. PhIP-DNA adducts could bedetected only in animals receiving 1 or 0.1 mg/kg/day, withhighest adduct levels in the pancreas, heart and kidneys. Therewas a good correlation (r = 0.77, p < 0.005) between thetwo methods of analysis, with average adduct levels determinedby ³²P-postlabeling     

Biomarkers of styrene exposure in lamination workers: levels of 06-guanine DNA adducts, DNA strand breaks and mutant frequencies in the hypoxanthine guanine phosphoribosyltransferase gene in T-lymphocytes

Occupational exposure to styrene was studied in nine workersof a hand lamination plant in Bohemia. Personal dosimeters wereused to monitor the styrene workplace exposure, and the levelsof styrene in blood and mandelic acid in urine were measured.Blood samples were taken at four occasions during a 7 monthperiod to determine styrene-specific 0⁶-guanine DNA adductsin lymphocytes and granulocytes, DNA strand breaks and hypoxanthineguanine phosphoribosyltransferase (HPRT) mutant frequency inT-lymphocytes. Seven administrative employees in the same factory(factory controls) and eight persons in a research laboratory(laboratory controls) were used as referents. DNA adduct levelsdetermined by the ³²P-postlabelling method in lymphocytes oflamina-tors were remarkably constant and significantly higher(P < 0.0001) than in factory controls at all four samplingtimes. HPRT mutant frequencies (MF) measured by the T-cell cloningassay were higher in the laminators (17.5 x10^–6, groupmean) than in the factory controls (15.7x10^–6, group mean)at three of the four sampling times, but the differences werenot statistically significant. However, a statistically significant(P = 0.021) difference between MF in the laminators (18.0 x10^–6,group mean) and laboratory controls (11.8 xl0^–6, groupmean) was observed at sampling time 4 (the only sampling timewhen this latter group was studied). This result indicates thatstyrene exposure may induce gene mutation in T-cells in vivo.DNA strand breaks were studied by the ‘Comet assay’at the fourth sampling time. The laminators were found to havesignificantly higher levels of DNA strand breaks than the factorycontrols (P = 0.032 for tail length, TL; P = 0.007 for percentageof DNA in tail, T%; and P = 0.020 for tail moment, TM). A statisticallysignificant correlation was also found between the levels oflymphocyte DNA adducts and all three DNA strand break parameters(TL P = 0.046; T% P = 0.026 and TM P = 0.034). On the contrary,no significant correlations were found between DNA adduct levelsand the HPRT mutant frequencies or between the mutant frequenciesand DNA strand breaks. Taken together, these results add furthersupport to the genotoxic and possibly mutagenic effects of styreneexposure in vivo. However, no simple quantitative relationshipseems to exist between the levels of styrene-induced DNA damageand frequency of HPRT mutation in T-lymphocytes.     

32P-Post-labeling detection of DNA adducts in mononuclear cells of workers occupationally exposed to styrene

³²-Post-labeling was used to analyze for the presence of DNAadducts in 47 workers exposed to styrene in a boat manufacturingfacility. Individual airborne exposures measured several timesover the course of 1 year ranged from 1to 235 mg/m³ with a meanvalue of 65.6 mg/m³. Two adducts were detected in the DNA ofmononuclear cells of these workers. The following levels ofadducts were detected: adduct 1, range 0.6–102x10^–8(mean 15.8x10^–8); adduct 2, range 0.1–70.9x10^–8(mean 14.2x10^–8). Significant linear relationships werefound between styrene exposure and both DNA adducts (adduct2, r = 0.330, P = 0.012; adduct 1, r = 0.244, P = 0.049). Co-chromatographyexperiments identified DNA adduct 1 in the exposed samplesasN²-(2-hydroxy-1-phenylethyl)-2'-deoxyguanosine-3', 5'-bisphosphate.DNA adduct 2 remains unidentified. No significant linear relationshipswere observed between the level of DNA adducts and sister chromatidexchanges, possibly because of the poor precision of the ³²-post-labelingassay (the estimated coefficients of variation for adducts 1and 2 were 2.54 and 1.96, respectively). These results demonstratethat occupational exposure to styrene results in the formationof DNA adducts in human mononuclear cells.     

DNA adduct levels of 2-amino-l-methyl-6-phenylimidazo-[4,5-b]pyridine (PhIP) in tissues of cynomolgus monkeys after single or multiple dosing

DNA adducts of 2-amino-l-methyl-6-phenylimidazo[4,5-b]-pyridine(PhIP), a heterocyciic amine derived from cooked meat, weremeasured by the ³²P-postlabeling method in tissues of cynomolgusmonkeys given PhIP. Monkeys received either a single dose ofPhIP (20 mg/kg orally) or nine daily doses of PhIP (20 mg/kgorally, days 1–5 and 8–l1) and tissue samples wereobtained 24 h after the last dose. Over 28 different tissueswere examined for PhIP—DNA adducts. Adducts were detectedin all tissues examined except the fat and bone marrow. Aftera single dose, adduct levels (mean value/10⁷ nucleotides, n= 2 monkeys) were highest in the liver (2.1), followed by thelung (1.7), gall bladder (1.7) and pancreas (0.9). Low adductlevels were detected in the brain and aorta (0.06 and 0.02 respectively).Following multiple doses of PhIP, adduct levels (mean value/10⁷nucleotides ± SE, n = 3 monkeys) were highest in theheart (5.7 ± 2.0) followed by the liver (3.8 ±0.8), submandibular gland (2.7 ± 1.8) and pancreas (2.2± 0.5). Comparison of the adduct levels after a singledose with those found after multiple doses indicates that accumulationof PhlP—DNA adducts occurred in certain tissues. Adductlevels in liver, pancreas, kidney, small intestine and colonincreased about 1.5- to 2.4-fold. PhlP—DNA adduct levelsin submandibular gland and brain increased 4- to 5-fold. Adductlevels in heart increased 10-fold and levels in the aorta increased31-fold. Adducts in white blood cell DNA increased with dailydosing for 9 days. No apparent changes in adduct levels wereseen in the lung, stomach, bladder, muscle and spleen. The widedistribution of PhlP-DNA adducts and their presence in whiteblood cells suggests that there is transport of reactive metabolitesfrom the liver to extrahepatic tissues. The relatively highadduct levels in the gall bladder in comparison with the liversuggests biliary excretion and possible reabsorption of reactivemetabolites. The presence of DNA adducts in tissues implicatesPhIP as a potential carcinogen in non-human primates. The possibilitythat PhlP-DNA adducts in tissues such as the heart and aortamay have toxicological consequences is discussed.     

Use of the 32P-postlabeling method to detect DNA adducts of 2-amino-3-methylimidazolo[4, 5-f]quinoline (IQ) in monkeys fed IQ: identification of the N-(deoxyguanosin-8-yl)-IQ adduct

Eight DNA adducts of 2-amino-3-methylimidazolo[4, 5-f]-quinoline(IQ) were found by the standard ³²P-postlabeling method in liversfrom male Cynomolgus monkeys fed IQ (5 days/week, 3 weeks, 20mg/kg,nasal-gastric intubation). The IQ-DNA adduct fingerprints observedin monkeys were identical to those observed in rats that receivedIQ (0.03%) in the diet for 2 weeks. The C8-guanine-IQ adductwas identified by comigration with the synthetic 3‘, 5’-bisphosphatederivative of N(-deoxyguanosin-8-yl)-Q. DNA modified in vitrowith N-hydroxy-IQ showed seven adducts, including the C8-guanine-IQadduct, that were identical to those found in monkeys and rats.Thus it appears that N-hydroxy-IQ, the reactive metabolite ofIQ, was responsible for all adducts found in vivo, except one.In order to detect adducts in other organs that were presentat lower levels, the intensification (ATP-deficient) methodfor ³²P-postlabeling was used. Five of the adducts detectedunder standard conditions, including the C8-guanine-IQ adduct,were also detected under intensification conditions. The totallevel of DNA-IQ adducts was highest in the liver, followed bythe kidney, colon and stomach, and bladder. The adduct patternswere identical in all organs examined. The results indicatethat IQ is potentially genotoxic in primates and therefore alikely human carcinogen.     

Seasonal variation of aromatic DNA adducts in human lymphocytes and granulocytes

DNA adducts were measured by ³²P-postlabelling in lymphocytesand granulocytes of 75 healthy men exposed occupationally andenvironmentally to high concentrations of aromatic compoundsin the ambient air. Volunteers enrolled in the study were menworking at the coke batteries and non-occupationally exposedinhabitants of Silesia, a highly industrialized region in southernPoland. Blood samples were drawn twice: in February and September1992. Seasonal. variations in the levels of DNA adducts werefound only in lymphocytes: 3.6- and 8.7-fold in the occupationallyand environmentally exposed groups respectively. In smokersthe seasonal variation was as large as 12.8-fold in the environmentallyexposed group. No seasonal variations were observed in granulocytes.The observed seasonal variation in the level of aromatic DNAadducts coincided with winter/summer differences in the concentrationsof benzo[     

DNA adducts, detected by 32P-postlabelling, in DNA treated in vitro with bile from patients with familial adenomatous polyposis and from unaffected controls

Patients with familial adenomatous polyposis (FAP) have a highrisk of developing duodenal adenomas and carcinomas. The distributionof these neoplasms resembles mucosal exposure to bile, suggestingthat bile may play a role in adenoma development. Our previousresults, using DNA adducts detected by ³²P-postlabelling asan index of genotoxicity, have supported this hypothesis. Wefound significantly higher adduct labelling in the duodenumof FAP patients than in the duodenum of control patients andsignificantly higher labelling in the small bowel of rats gavagedwith FAP bile than in rats given control bile. We have now investigatedthe ability of human bile to form adducts with DNA in vitro.Bile obtained from the gallbladder of 18 FAP patients immediatelybefore colectomy, and from 18 control patients, was incubatedwith salmon sperm DNA in solution at 37^°C for 1 h, afterwhich the purified DNA was analysed for DNA adducts, using thenuclease PI method of ³²P-postlabelling. Relative adduct labellingvalues (RAL, adducts per 109 nucleotides) produced by FAP bilesamples were significantly higher than RAL values produced bycontrol bile samples (medians 197 versus 86, P = 0.0016, Mann-Whitneytest). We found a consistent pattern of adduct labelling, varyingin intensity between samples. Adduct spots were eluted fromTLC plates and analyzed by reverse-phase HPLC. Each major spotgave several peaks that were consistent between bile samplesfrom different patients and were similar in FAP and controlbile. These results indicate that bile from FAP and controlpatients contains similar, directly acting genotoxic compoundsbut that levels are higher in FAP than in control patients.This suggests that bile from FAP patients is more genotoxk thanbile from control patients. Incubation of bile with free-radicalscavengers and deconjugating enzymes failed to influence adductlabelling in this system.     

Persistence, gestation stage-dependent formation and interrelationship of benzo[a]pyrene-induced DNA adducts in mothers, placentae and fetuses of Erythrocebus patas monkeys

Since DNA adducts have been detected in the placentae of pregnantwomen who smoke cigarettes, the importance of these adductsas biomarkers of fetal exposure and risk has been evaluatedusing a non-human primate as a model. Pregnant Erythrocebuspatas monkeys on days 50, 100 or 150 of gestation (term = 160± 5 days) were treated once with 5–50 mg/kg benzo[a]pyrene(B[a]P), p.o. Fetuses were removed by Cesarean section 1–50days after treatment and analyzed for DNA adducts by the nucleaseP₁ version of the ³²P-postlabeling method. B[a]P induced highlevels of DNA adducts in all fetal organs, placentae and maternallivers in all three trimesters of gestation. DNA adduct levelswere higher in mid-gestation compared to early and late gestation.The major adduct detected was 10ß-(deoxyguanosin)-N²-yl-7ß,8     

Possible mechanisms for PhIP-DNA adduct formation in the mammary gland of female Sprague-Dawley rats

2-Amino-l-methyl-6-phenylimidazo[4, 5-b]pyridine (PhIP), themost abundant heterocyclic amine in fried beef, is a mammarygland carcinogen in rats. Using the ³²PP-postlabeling method,PhIP-DNA adduct levels were measured in mammary epithelial cellsisolated from female Sprague-Dawely rats given 10 daily dosesof PhIP (75 mg/ kg, p.o.) according to a protocol previouslyshown to induce mammary gland cancer. At 24 h, 48 h, 1 weekand 5 weeks after the last dose of PhIP, PhIP-DNA adduct levels[relative adduct labeling (RAL) x 10⁷, mean ± SD] were10.2 ± 0.7, 7.9 ± 2.7, 2.2 ± 0.6 and 0.9± 0.03 respectively. When isolated rat mammary epithelialcells (from untreated rats) were incubated in vitro with N-hydroxy-PhIP(45 µM, 1 h, 37°C), PhIP-DNA adducts were detectedin cell DNA (RAL =     

32P-Postlabeling of a DNA adduct derived from 4,4'-methylenedianiline, in the olfactory epithelium of rats exposed by inhalation to 4,4'-methylenediphenyl diisocyanate

Tissues obtained from female Wistar rats exposed to a 0.9 µmaerosol of 4,4'-methylenediphenyl diisocyanate (MDI) for 17h per day, 5 days per week, for one year, at levels of 0, 0.3,0.7 and 2.0 mg/m³, were analyzed for DNA adducts. A ³²P-postlabelingmethod was used to detect (i). adducts formed by the reactionof the isocyanate group(s) of MDI with DNA; and a ³²P-postlabelingmethod was adapted to detect (ii), a DNA adduct formed by 4,4'-methylenedianiline(MDA), a hydrolysis/decarboxylation product of MDI. In the lung,neither isocyanate adducts nor the arylamine adduct were detectable.The same negative result was seen in the liver, the bladder,the kidney, the respiratory epithelium and in peripheral lymphocytes.In the olfactory epithelium, on the other hand, the aryl-amine-derivedDNA adduct was detected, at the very low levels of 5, 9 and10 adduct-nucleotides per 10¹⁰ nucleotides, for the three dosegroups, respectively. The adduct co-chromatographed with theone formed in the liver of rats after oral gavage of MDA. Theresults are discussed in terms of the importance of genotoxicversus nongenotoxic aspects of carcinogenesis.     

Aromatic DNA adducts in larynx biopsies and leukocytes

Larynx cancer is strongly associated with tobacco smoking. Theobjective of this work was an analysis of aromatic DNA adductsin tumour and non-tumour larynx cells by means of the ³²P-postlabellingmethod. Peripheral blood leukocytes were used as a referencetissue. The presence of aromatic DNA adducts was demonstratedin all the studied tissues obtained after surgery of larynxtumours. The highest level of DNA adducts was found in larynxtumour cells, followed by non-tumour larynx cells, which exceededthat found in leukocytes almost 2.5 times. Large interindividualdifferences were detected between subjects. The adduct levelin tumour/non-tumour correlated only moderately. However a highcorrelation was found between the level of DNA adducts in larynx(tumour and nontumour) cells and that in leukocytes.