p53 Mutations and Occupational Exposures in a Surgical Series of
Transcription
p53 Mutations and Occupational Exposures in a Surgical Series of
Vol. 5, 997-/O()3. p53 !)eeember Cancer /996 Mutations and Occupational Exposures Lung Epidemiology Branch IL. C. H.. N. E. Cl, Laboratory of Pathology IL. A. LI, and Laboratory of Human Carcinogenesis ID. G. G.. W. P. B.. C. C. HI, National Cancer Institute. National Institutes of Health, Bethesda, Maryland 20892: Department of Pulmonary and Mediastinal Pathology, Armed Forces Institute of Pathology. Washington. D. C. 20306 ID. G. G., W. D. TI; and Mayo Clinic. Rochester. Minnesota 55905 lJ. J.. T. V. C.. H. T.. V. T.. P. P.1 Abstract p53 mutations are frequent in malignant lung tumors. Of 88 surgically treated lung cancers from cigarette smokers previously evaluated for p53 mutations, 45 tumors (51.1%) had mutations in exons 5-8 (D. G. Guinee, Jr. et a!., Carcinogenesis (Lond.), 16: 993-1002, 1995). We report here the examination of 13 occupational exposures and 13 high-risk occupations in relation to these p5.3 mutations. Two molecular abnormalities were associated with occupational exposures: (a) G:C-T:A transversions on the coding (nontranscribed) strand (n = 13) were associated with chromate exposure and employment in the metal industry (P < 0.05) and marginally associated with nickel exposure (P 0.056); and (b) G:C-*A:T transitions at non-CpG sites (n 9) were associated with work in the petrochemical industry (P 0.05). No association was found between p5.3 mutations and gender, cigarette pack-years, tumor histology, age at diagnosis, or family history of lung cancer. Because all three chromateexposed subjects had large cell carcinomas exhibiting G: C-”T:A coding-strand transversions, follow-up of a cohort with this exposure should clarify the association with the p53 gene. Introduction Lung cancer is the leading cause of cancer death in the United States ( I ). Epidemiological studies have linked several environmental agents to lung cancer, including tobacco smoke, asbestos, ionizing radiation, metals, polycyclic aromatic hydrocarbons, and chloromethyl ethers (2). Whereas an estimated 85% of lung cancer deaths may be attributable to cigarette smoking ( 1 ), other factors contribute independent effects as well as possible synergistic effects with cigarette smoke. Received The costs 4/ I 6/96: revised 8/2 1/96: accepted of publication of this article were 8/26/96. defrayed in part by the payment in a Surgical Biomarkers Series & Prevention of Cancers Lea C. Harty, Donald G. Guinee, Jr., William D. Travis, William P. Bennett, James Jett, Thomas V. Colby, Henry Tazelaar, Victor Trastek, Peter Pairolero, Lance A. Liotta, Curtis C. Harris, and Neil E. Caporaso’ Genetic Epidemiology, of page charges. This article must therefore be hereby marked advertiseme,it in accordance with 18 U.S.C. Seciion 1734 solely to indicate this fact. I To whom requests for reprints should be addressed. at Genetic Epidemiology Branch. Executive Plaza North, Room 439, 6130 Executive Boulevard, MSC 7372. Bethesda. MD 20892-7372. At the molecular level, mutation of the p53 gene is the most frequent somatic genetic alteration found in malignant lung tumors (3). The prevalence of p53 mutations is considerably lower in adenocarcinomas (33%) than in other histological types of lung cancers (60-70% of small cell, large cell, and squamous cell carcinomas; reviewed in Ref. 3). The p53 protein regulates gene transcription (4) and is thought to play a role in many fundamental cellular activities including cell cycle control, DNA repair and synthesis, cell differentiation, genomic plasticity, and apoptosis (5). Mutations may be classified as transitions or transversions. Transitions involve a change from one purine [adenine (A) and guanine (G)] to another or from one pyrimidine [cytosine (C) and thymine (T)j to another. G:C-”A:T transitions (the notation refers to a G to A change in which a G:C pair is replaced by an A:T pair after one round of DNA replication) may be further classified according to whether they occur at CpG sites (DNA sequences in which a cytosine is followed by a guanine in the 5’-3’ direction). The cytosines in a CpG dinucleotide are frequently methylated, which predisposes to spontaneous deamination of 5-methylcytosine to thymidine: this spontaneous deamination is generally unrelated to environmental exposures (6,7). Transversions involve the replacement of a purine with a pyrimidine or replacement of a pyrimidine with a purine. The mutational spectrum of a gene consists of the type and distribution of mutations within a target sequence. Mutational spectrum analysis has shown that patterns of mutations can reflect etiological agents or processes (3). Presently, five environmental agents have been linked to human cancers and have characteristic p53 mutational spectra: (a) hepatocellular carcinomas associated with aflatoxin B1 exposure contain a predictable mutation at codon 249, AGG-*AGT, resulting in the substitution of serine for arginine (8, 9): (b) sunlight-associated skin cancers have mutations at dipyrimidine sites that are usually G:C-”A:T transitions and also exhibit characteristic CC: TT-TT:AA mutations (10); (c) hepatic angiosarcomas associated with vinyl chloride exposure have frequent mutations almost exclusively at A:T bp ( 1 1 ). This is consistent with the mutational activity of the vinyl chloride monomer, and it contrasts with relatively infrequent G:C-”A:T mutations in sporadic angiosarcomas (12); (d) p53 mutation in oral cancers correlates with a patient’s tobacco and alcohol consumption (13); and (e) the mutational spectrum of lung cancers is dommated by G:C-”T:A transversions with a coding (nontranscribed) strand bias that account for 40% of all mutations (3). This spectrum can be explained by DNA adducts formed by polycyclic aromatic hydrocarbons and preferential repair of the noncoding (transcribed) strand (3). Several investigators report a dose-response relationship between smoking history and the prevalence of p53 mutations (14, 15). Previously, a series of lung malignancies was examined for p.53 mutations, and the mutational spectrum was reported ( 16). The goal of the present study was to determine whether Downloaded from cebp.aacrjournals.org on October 19, 2016. © 1996 American Association for Cancer Research. 997 998 p53 Mutations and Occupational Exposures in Lung occupational factors are associated with the tations among smokers. In particular, G:C-”A:T mutations were studied because ularly susceptible to attack by electrophilic G:C-”T:A and G:C-A:T changes are the lung cancers, accounting for 40% and 24% respectively (3). Cancer observed p53 muG:C-T:A and guanine is particspecies, and most common in of p53 mutations, Table I Characteristics of subjects and their tumors and No. Percent Male 50 56.8 Female 38 43.2 87 98.9 I 1.1 Hispanic Age Study Population. Patients with primary lung cancer were identified through the Thoracic Surgery Department at the Mayo Clinic in Rochester, Minnesota in 1991-1992 before resection. A total of 107 patients meeting the following eligibility criteria were enrolled in the study: (a) no cancer diagnoses in the year preceding lung cancer diagnosis; (b) no chemotherapy or radiation treatment to the trunk before specimen collection: (e) lung tumor histology other than lymphoma; (d) mental competence; (e) able to comprehend and communicate with study staff using the English language; (f) at least three pieces of tumor tissue and three pieces of normal lung available at resection; and (g) 15 cc of blood available for study. All subjects provided informed consent for participation in the study. Five patients who had never smoked at least I 00 cigarettes (“nonsmokers”) were excluded from the analysis because of potential etiological differences between their tumors and those that occurred in smokers. p.53 sequence data were not available for 13 patients and occupational exposure data were not available for I patient. resulting in a final sample size of 88. Covariate Data. Information regarding tumor stage was abstracted from the patient’s medical record. Malignancies were classified using the Tumors-Nodes-Metastasis Staging System for lung cancer (17). A 30-mm questionnaire was administered to each patient after surgery by a nurse or respiratory therapist. The questionnaire included items regarding demographics, tobacco use, medical history, occupational history, residential history, and family medical history. Within the occupational history section, subjects were asked about lifetime exposures to 13 occupational hazards and past or present employment in I 3 industries. These occupational exposures and industries were chosen because they are putative lung cancer risk factors or because they were common in the Mayo Clinic referral area. A complete occupational history was elicited that included all jobs held for at least six months, job titles, activities or duties, name and address of company or organization, the type of business or products made, years of employment, and number of hours worked per week. No attempt was made to verify the self-reported information provided at interview. Genomic DNA Extraction, Amplification, and Sequencing. p53 mutations in exons 5-8 were previously determined (16); a brief description of the methodology used is presented here. p53-specific intron primers were used in the PCR to generate a 538-bp fragment encompassing exons 5 and 6 and a 660-bp fragment encompassing exons 7 and 8. In rare cases in which the DNA did not amplify with this procedure, individual exons were amplified using nested primers (18). Gel-purified PCR 88) Race Methods Specimen Collection. Specimen collection procedures have been described previously ( 16). In brief, three pieces of tumor and three pieces of adjacent nonmalignant tissue were collected from each patient at the time of resection and snap-frozen within 1 h. Tissues were stored at -70#{176}Cbefore DNA extraction and PCR. Formalin-fixed paraffin-embedded blocks were collected for histological review. = Gender White Materials (n at diagnosis Mean (yrs) 65.5 ± SD Range Tumor ± 9.4 35-81 - histology Adenocarcinoma 42 47.7 25 28.4 carcinoma 20 22.7 carcinoma I 1.1 Squamous cell Large cell Small cell Tumor stage carcinoma at diagnosis 40 45.5 II 16 18.2 lilA 23 26.1 IIIB 4 4.5 IV 3 3.4 Unknown 2 2.3 No 75 85.2 Yes 13 14.8 At least one Cigarette parent or sibling with lung cancer pack-years Males Mean ± SlY’ 60.8 ± 39.5 0.5-166.9 Range Females Mean 46.7 ± SD “ P < 0.05 ± 22.5 0.8-103.0 Range (males versus females). products were sequenced by a modification of the dideoxy chain-termination method of Sanger et a!. (19). Both strands of each exon were sequenced to identify putative mutations. Germ-line mutations were excluded by repeat amplification and sequencing of genomic DNA isolated from paired nonneoplastic lung tissue. Data Analysis. Univariate analyses were performed for the following variables: gender, age at diagnosis, tumor histology, history of lung cancer in at least one parent or sibling, lifetime smoking dose expressed as cigarette pack-years, and 26 occupational factors. Associations between these factors and p53 mutations were evaluated using Fisher’s exact test (20) as determined by the SAS (2 1) procedure PROC FREQ on a mainframe computer or by an exact trend test (22) for factors with more than two levels. Associations were considered statistically significant if the two-tailed P was less than 0.05. Student’s t tests, implemented through the SAS procedure PROC ITEST, were used to compare mean values for selected variables. Results Selected characteristics of the 88 subjects and their tumors are presented in Table 1 . Both genders were well represented in this series, which was predominantly if not entirely Caucasian (one subject described his race as Hispanic and did not indicate if he was Caucasian or African-American). When classified by histology, 47.7% of the tumors were adenocarcinomas, 28.4% were squamous cell carcinomas, 22.7% were large cell carcinomas, and I . 1% were small cell carcinomas. Reflecting the Downloaded from cebp.aacrjournals.org on October 19, 2016. © 1996 American Association for Cancer Research. Cancer Table 2 Numbers and Type G.C of mutations of mutation found . in 88 lung On strand noncoding No. %ofall . mutations strand 13 27.7 3 6.4 A:T -“ At CpG site 4 8.5 9 19.1 G:C-’C:G 3 6.4 A:T-sT:A 3 6.4 4 8.5 At non-CpG A:T site G:C -“ I A:T-+C:G Deletions and Total of mutations no. insertions No. of tumors with at least one p53 No. of tumors with no p53 mutations mutation” 2.1 7 14.9 47 100.0 45 43 489b One tumor had two G:C -. T:A mutations (one on the coding on the noncoding strand); one tumor had a G:C -“ T:A mutation strand and a G:C -‘ A:T mutation at a non-CpG site. S Percentage of all tumors. “ malignancies T:A -“ On coding G:C types 51.1” strand and one on the coding eligibility requirement of resectability, tumors tended to be diagnosed at early stages, with 79 (90.0%) classified as Stage I, II, or lIlA. All subjects smoked for at least six months. Average cigarette pack-years differed by gender. Men reported an average of 60.8 cigarette pack-years compared with 46.7 cigarette pack-years for women; however, the range for both sexes was wide. p53 mutations were found in 45 of 88 tumors (51 .1%). The mutational spectrum for the entire tumor series (n 107) has been described in detail previously (16); those found in the 88 tumors included in the present analysis are summarized in Table 2. The most common type of mutation, a G:C-T:A transversion, was found in 16 (34.1%) tumors. Thirteen of these I 6 transversions were on the coding strand. Thirteen tumors (27.6%) exhibited G:C-A:T transitions, nine of which were at non-CpG sites. Other base changes, deletions, and insertions were less frequently observed. Subjects provided information about 13 occupational exposures and a history of employment in 13 industries (Table 3). Of the I 3 exposures, agricultural pesticides or herbicides, reported by 2 1 subjects, were the most common. Exposures to crude petroleum refining, radiation, asbestos, coke oven gases, and dyes were each reported by at least five subjects. All other exposures were less common. When asked about employment in 13 industries, 10 subjects reported a history of employment in the construction industry, and 10 subjects reported holding jobs in the metal refining, manufacturing, plating, or polishing industries. None of the other industries surveyed were reported by more than four subjects. The relationship of G:C-*T:A transversions on the coding strand to various factors is shown in Table 3. No association was found between this type of p53 mutation and gender, cigarette pack-years, age at diagnosis, tumor histology, or family history of lung cancer. Of the occupational exposures, chromate exposure was significantly associated with G:C-”T:A coding strand mutations (P < 0.05). An association between occupational exposure to nickel and G:C-*T:A coding-strand transversions was also found (P = 0.056). A history of employment in the metal refining, manufacturing, polishing, or plating industries was also positively associated with this type of mutation (P 0.037). Limiting the analyses to males did not appreciably alter the findings (data not shown). Epidemiology, Biomarkers & Prevention Of 10 subjects who reported working in the metal industry, 1 reported chromate exposure, 1 reported nickel exposure, and 2 reported both chromate and nickel exposures. Thus, of three chromate-exposed subjects, only one was not exposed to nickel, and of three nickel-exposed subjects, only one did not report exposure to chromates. Table 4 presents the mutational features, tumor histologies, and specific metal exposures for the metal industry-exposed subjects. All three chromate-exposed subjects had large cell carcinomas with G:C-*T:A transversions on the coding strand. The work histories of the metal industry-exposed subjects were further examined. For 37 years before being diagnosed with lung cancer, Subject 10 worked in the custom manufacturing of kitchen appliances. Subject 29 worked a total of 42 years in manufacturing, 18 years of which involved aluminum welding and exposure to coal, and 24 years of which he served as manager for several aircraft manufacturing companies. He was diagnosed with lung cancer 26 years after his welding exposure began. Subject 3 1 was employed for 45 years as a welder and also engaged for 38 years in part-time construction work involving cement. He was diagnosed with lung cancer 51 years after beginning welding work. Subject 88 worked 8 years as a welder; she began this job 28 years before being diagnosed with lung cancer. Subject 103 performed a variety of activities at a gray iron foundry for 23 years; he developed lung cancer 37 years after he started working there. Subject 106 was employed as a dyemaker during the 28 years preceding his lung cancer diagnosis. Subject 107 was a welder for 27 years, having begun this job 28 years before developing lung cancer. There was no further information pertaining to employment in the metal industry for Subjects 65 and 66. G:C-”A:T transitions at non-CpG sites were also exammed for associations with potential risk factors (Table 3). Gender, cigarette pack-years, age at diagnosis, tumor histology, and family history of lung cancer were not associated with this type of mutation. Of the occupational factors, a history of employment in the petrochemical industry was positively associated with G:C-A:T transitions at non-CpG sites (P 0.05). One of the subjects who reported working in the petrochemical industry was employed as a truck driver for an oil refinery; the work histories of the other three subjects who reported work in the petrochemical industry did not provide any further information about their jobs. The mutations observed in this series of malignancies have been described in detail elsewhere ( 16). In Table 5, the mutational features of the 13 G:C’-T:A coding strand transversions and the 9 G:C-’A:T transitions at non-CpG sites studied in the present report are presented together with the subjects’ occupational exposures and tumor histologies. The majority of the changes were missense mutations; the resultant amino acid substitutions are indicated. Several subjects reported exposure to more than one of the occupational factors that were surveyed. Discussion Chromium and nickel compounds have been implicated in the etiology of lung cancer (23). The present study extends previous findings by providing evidence that such metals may be related to a specific type of mutation, G:C-*T:A transversions, in the p53 gene. This is consistent with Chen and Thilly’s (24) observation of K,Cr2O7-induced mutational hotspots involving G:C bp in the hypoxanthine guanine phosphoribosv! transferase gene and the G:C-T:A transversions in the K-ras gene in nickel-induced renal sarcomas in the rat reported by Higinbotham et a!. (25). An A:T-G:C transition in the p53 gene has Downloaded from cebp.aacrjournals.org on October 19, 2016. © 1996 American Association for Cancer Research. 999 1000 p53 Mutations Table and 3 Occupational Associations Exposures of putative risk in Lung factors with Cancer pSi G:C -“ T:A coding strand transversion among 88 lung cancer patients G:C No. with factor (%) No. with mutation -“ T:A coding strand % of G:C -“ mutations Gender and transversions T:A G:C -“ A:T G:C ,, No. with mutation transition -“ A:T mutations transitions Female Cigarette 2 22.2 3 33.3 3 33.3 ‘, 22.2 I 5.4 2 22.2 53.8 38 (43.2) 6 46.2 0.569 2 I 5.4 31.6-47.5 23 (26.1) 3 23.1 47.6-68.3 21 (23.9) 5 38.5 1.5 22 (25.0) 3 23.1 68.4-166.9 at diagnosis >0.900 I 1.1 0.758 (yrs) 55 >0.900 I 1 (12.5) 2 56-65 31 (35.2) 5 38.5 ., 22.2 >65 46 (52.3) 6 46.2 5 55.6 4 44.4 5 55.6 histology Other I parent or sibling diagnosed Yes with lung 42 (47.7) 4 30.8 46 (52.3) 9 69.2 cancer >0.900 13 (14.8) 75 (85.2) No Occupational ., II >0.900 15.4 1 1.1 84.6 8 88.9 exposures Smelting process 85 (96.6) No petroleum 12 92.3 8 88.9 2 22.2 7 77.8 2 22.2 7 77.8 0.156 5 (5.7) 83 (94.3) No I 1.1 7.7 refining Yes Agricultural 0.279 0.385 3 (3.4) Yes Crude 0.731 0.236 Adenocarcinoma 2 II I 5.4 84.6 pest/herbicides 0.080 0.177 Yes 21 (23.9) No 67 (76.1) 7.7 12 92.3 >0.900 0.156 Radiation Yes 5 (5.7) No 83 (94.3) 2 II 0.425 I 5.4 I 1.1 84.6 8 88.9 0 0.0 0.003 Chromates Yes 3 (3.4) 85 (96.6) No 3 23.1 10 76.9 Nickel >0.900 9 100.0 0.056 Yes 3(3.4) No 85 (96.6) Hematite or iron 2 II I 5.4 84.6 ore >0.900 0 0.0 9 100.0 0.275 Yes 2(2.3) No 86 (97.7) 0.195 1 1.1 7.7 12 92.3 Asbestos 8 88.9 0.163 Yes No 10 (11.4) 3 23.1 78 (88.6) 10 76.9 tars >0.900 11.1 8 88.9 0.385 Yes 3 (3.4) 85 (96.6) No 0.279 7.7 12 I 1.1 92.3 Chromium” 8 88.9 0 0.0 9 100.0 0 0.0 9 100.0 0.388 Yes 3(3.5) No 84 (96.5) 7.7 12 92.3 Uranium >0.900 >0.900 Yes No Coke sites A:T 0.289 77.8 7 22 (25.0) Coal sites at non-CpG % of G:C -“ mutations 7 50 (56.8) pack-years 0.5-3 Tumor at non-CpG >0.900 Male Age mutations oven Yes No I (1.1) 0 0.0 87 (98.9) 13 100.0 gases >0.900 6(6.8) 82 (93.2) No 0.487 I 1.1 7.7 12 8 92.3 Dyes Yes >0.900 88.9 >0.900 6(6.8) 0.487 I 1.1 7.7 82 (93.2) 12 92.3 Yes 1 (1.1) 0 No 87 (98.9) 13 8 88.9 0.0 0 0.0 100.0 9 100.0 Industries Shipbuilding >0.900 >0.900 Downloaded from cebp.aacrjournals.org on October 19, 2016. © 1996 American Association for Cancer Research. Cancer Table 3 (cont’d.)-Associations of putative risk factors with p53 G:C sites G:C No. with factor (%) -“ T:A -“ among T:A No. with mutation coding strand 88 lung coding transversion cancer strand % of G:C -“ mutations transversions T:A 10(11.4) 2 No 78 (88.6) II I (1.1) No 87 (98.9) 1 7.7 12 92.3 3 (3.4) 0 0.0 No 85 (96.6) 13 100.0 at non-CpG A:T transitions at non-CpG % of G:C mutations sites A:T 1 11.1 8 88.9 0 0.0 9 00.0 1 I 1.1 8 88.9 2 22.2 7 77.8 1 1 1.1 8 88.9 2 22.2 7 77.7 0 0.0 >0.900 0.279 0.102 No 4 (4.5) 2 15.4 84(95.5) II 84.6 chemicals 0.050 >0.900 Yes 3 (3.4) 0 0.0 No 85 (96.6) 13 100.0 Metal 0.279 0.037 Yes No Sugar 10 ( I I .4) 4 30.8 78 (88.6) 9 69.2 cane 0.270 >0.900 Yes I (I. I) No 87 (98.9) 0 0.0 13 100.0 Mining >0.900 9 100.0 0 0.0 9 100.0 0.148 Yes I (I. I) No 87 (98.9) I 7.7 12 92.3 Insulation I ( I. I ) No 87 (98.9) Asbestos 0 0.0 13 100.0 No 9 2(2.3) 1 7.7 100.0 86(97.7) 12 92.3 >0.900 0 manufacturing 0.0 9 100.0 0 0.0 9 00.0 >0.900 Yes I ( I.I) No 87 (98.9) 0 0.0 13 100.0 Demolition >0.900 >0.900 Yes 1 ( 1. I ) No 87 (98.9) test used exposure for cigarette unknown Table no. for 4 pack-years and 1 subject; analysis Mutational Chromate features, exposure 0.0 0 0.0 13 100.0 9 100.0 age at diagnosis; based tumor Nickel Fisher’s exact test used for all other histology, and chromate and exposure nickel Mutation exposures 29 Yes Yes G:C 31 No No None 65 No No G:C 66 No No None 88 Yes No G:C 91 No No None 103” No Yes G:C -“ A:T CpG 106 Yes Yes G:C -“ T:A coding strand 107 No No G:C -“ T:A coding strand G:C -“ A:T non-CpG 103 was found after publication worked -‘ T:A coding strand A:T non-CpG Codon site 249 Codon T:A coding strand 143 Codon 249 site and histology Large cell carcinoma Adenocarcinoma Large cell carcinoma Large cell carcinoma cell carcinoma Codon 248 Squamous cell carcinoma Codon 245 Large carcinoma Codon 160 Adenocarcinoma Codon 161 - site Tumor Adenocarcinoma - industry Adenocarcinoma -“ in the metal location - of Ref. observed by Maehle et a!. (26) in human renal epithelial treated with nickel. The mechanism(s) by which metals exert their carcinogenic effects may involve oxidative damage resulting in DNA base modifications, cross-linking of DNA with proteins and/or adjacent DNA bases, DNA cleavage, who Mutation None Subject in subjects type No from factors. on 87 subjects. No in the tumor >0.900 0 10 mutation 0.0 0.275 Yes Cement >0.900 0 manufacturing trend >0.900 >0.900 Yes been cells mutations >0.900 84.6 Yes Other The transition >0.900 Yes “ A:T 0.148 Yes Subject -“ No. with mutation 15.4 Petrochemicals Exact -‘ & Prevention 0.638 Yes Wood/paper Chromium G:C , Fishing S and G:C Blomarkers patients Construction “ mutations Epidemiology, Squamous cell 1. and/or depurination (reviewed in Ref. 27). The role of particular metals (e.g., nickel versus chromates) could not be resolved in the present study because coexposure was more common than single exposure. In contrast to recent work by Wang et a!. (28), we did not observe an increased frequency of G:C-+T:A trans- Downloaded from cebp.aacrjournals.org on October 19, 2016. © 1996 American Association for Cancer Research. /00/ /()02 p53 Mutations 5 Table and Occupational Muiational features, Exposures tumor in Lung histologies. and Cancer occupational exposures associated transitions at non-CpG G:C Subject no . -_____________________________ Codon or . . splice site Base Mutation class chance ,, the G:C 9)” strand s T:A coding strand transversions (n Tumor . histology Occupational , Asbestos; asbestos . AGG > ATG mis Arg > Met sq cell I 58 CGC > CTC mis Arg > Leu adenoca - 14 245 GGC > GTC mis Gly > Val adenoca 22 298 GAG > TAG non Glu > Ter sq cell 29 249 AGG > AGT mis Arg > 5cr Ig cell Radiation; > GT spl - sq cell Crude petroleum petrochemical 7 3 splice site GG manufacturing - chromates; nickel: coke oven gases; refining; construction md.; mining md. 158 CGC > CTC mis Arg > Leu adenoca - 71 266 GGA > GTA mis Gly > Val sq cell - 80 294 GAG > TAG non Glu > Ter Ig cell 88 249 AGG > AGT mis Arg > 5cr lg cell md.; metal 158 CGC > CTC mis Arg > Leu sq cell 245 GGC > GTC mis Gly > Val Ig cell Smelting process; agricultural herb/pesticides: chromates; nickel; hematite or iron ore; tars; chromium; dyes; metal md. 107 161) ATG > All’ mis Met > lie adenoca Crude petroleum petrochemical Codon . splice or . site Base change Mutation class ,, transitions - at non-CpG Amino acid change Tumor . histology refining; asbestos; md.; metal md. . Occupational ,, 275 TGT > TAT mis Cys > Tyr adenoca 167 CAG > TAG non GIn > Ter Ig cell Agricultural pest/herbicides; oven gases 38 193 CAT > TAT mis His > Tyr adenoca Wood/paper 65 143 GTG > ATG mis Val > Met adenoca Smelting process; pest/herbicides; petrochemical 69 179 CAT > TAT mis His > Tyr sq cell - 72 242 TGC > TAC mis Cys > Tyr Ig cell - 97 245 GGC > AGC mis Gly > 5cr adenoca 102 159 GCC > GTC mis Ala > Val sq cell Crude 107 161 GCC > GTC mis Ala adenoca Construction features mis. have been missense: previously reported non, nonsense: spl. (16), splice md.; b - hematite or iron ore; coke md. crude petroleum refining; agricultural radiation; coal tars; dyes; md.; other chemical md.; metal md. - petroleum except for those in the tumors from Subjects 71, 98, and 102. site; sq cell, squamous cell carcinoma; adenoca, adenocarcinoma; versions in the p53 gene in lung cancer patients occupationally exposed to asbestos, despite the relatively high prevalence of this exposure (10 of 88 patients, I 1.4%) in the present study. A limitation of this study is the use of self-reported occupational exposure data, which may introduce misclassification. However, when patients’ complete occupational histories were evaluated for consistency with self-classification as “exposed”, subjects who reported an exposure also reported a job title or duty that is known or suspected to involve that exposure. In addition, among patients who reported work in the metal industry, the age at lung cancer diagnosis (mean = 61.3 years; range = 35-75 years) and the number of years between first occupational exposure and tumor development are similar to those reported in other studies (29, 30), providing further support for the use of self’-reported occupational data in this study as a surrogate measure of exposure. Only hexavalent chromium compounds have been established as carcinogens (23); the effect found in this study was specific for chromates. The distribution of histological types of lung cancer in chromate-exposed persons is not consistent in the literature. All three chromate-exposed persons in our study had large cell carcinomas. In contrast, squamous cell carcinomas predominated in three previous reports of lung malignancies in chromate- or nickel-exposed persons (31-33). However, Abe et a!. construction factors 37 Mutational Abbreviations: radiation; asbestos; coal sites 25 > Val md. md.; md. 98 A:T metal fishing - Chromates; 106 -“ A:T - md. 50 G:C G:C S factors 174 Exon 13) and transversions Amino acid change 5 Subject no . “ coding (,i II 48 “ T:A - with sites refining; md.; asbestos; petrochemical lg cell, large md.; cell metal carcinoma; md. md., industry. (33) reported that small cell carcinomas (n = 5) occurred in employees who worked exclusively in those parts of the chromate manufacturing process involving exposure to hexavalent chromate dusts. The role of chance must be considered in interpreting the statistically significant associations in this study because a large number of comparisons were made, and some exposures were present in only a small number of subjects. The small sample size also prevented multivariate adjustment when examining the relationship of occupational exposures to p53 mutations. However, there was no association between p53 mutations and several potential confounders (gender, cigarette pack-years, age at diagnosis, tumor histology, and family history of lung cancer). In contrast to previous work (14, 15), we failed to observe a significant association between cigarette pack-years or other measures of smoking duration and intensity (data not shown) and G:C-t’T:A transversion mutations in this study. However, a weak trend may be present, i.e. I 9.3% of tumors from subjects with less than the median number of pack-years versus 30.8% of tumors from subjects with greater than the median number of pack-years exhibited G:C-*A:T mutations. It is noteworthy that all three chromate-exposed persons had large cell carcinomas and G:C-”T:A transversions on the Downloaded from cebp.aacrjournals.org on October 19, 2016. © 1996 American Association for Cancer Research. Cancer coding strand. occupationally This finding warrants exposed cohort. follow-up in a larger, 16. 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Chromate lung cancer with special reference to its cell type and relation to the manufacturing process. Cancer (Phila.), 49: 783-787, 1982. Downloaded from cebp.aacrjournals.org on October 19, 2016. © 1996 American Association for Cancer Research. p53 mutations and occupational exposures in a surgical series of lung cancers. L C Harty, D G Guinee, Jr, W D Travis, et al. Cancer Epidemiol Biomarkers Prev 1996;5:997-1003. Updated version E-mail alerts Reprints and Subscriptions Permissions Access the most recent version of this article at: http://cebp.aacrjournals.org/content/5/12/997 Sign up to receive free email-alerts related to this article or journal. To order reprints of this article or to subscribe to the journal, contact the AACR Publications Department at pubs@aacr.org. To request permission to re-use all or part of this article, contact the AACR Publications Department at permissions@aacr.org. 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