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Although exposure to estrogen may directly influence or modify the association between cigarette smoking and lung cancer risk, results from epidemiologic studies examining the association between reproductive and hormonal factors and risk of lung cancer among women have been inconsistent. Between 1998 and 2008, 430 women diagnosed with nonsmall cell lung cancer, 316 hospital controls and 295 population controls were recruited into the multi-center Maryland Lung Cancer Study. Conditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) according to reproductive and hormonal exposures adjusting for age, smoking, passive smoking, education and household income. Results were similar for hospital and population based controls, so the control groups were combined. Reduced risks of lung cancer were observed among women with greater parity (≥ 5 vs. 1-2 births: OR = 0.50, 95% CI = 0.32, 0.78, p-trend = 0.002) and later ages at last birth (≥ 30 vs.

Nitric oxide (NO•), an important signaling molecule and a component of inflammatory response, is involved in tumorigenesis. However, the quantity of NO• and the cellular microenvironment influences the role of NO• in tumor development. We used a genetic strategy to test the hypothesis that an inflammatory microenvironment with an enhanced level of NO• accelerates spontaneous tumor development. C. parvum–induced inflammation and increased NO• synthase-2 (NOS2) expression coincided with accelerated spontaneous tumor development, mostly lymphomas, in p53−/−NOS2+/+ C57BL6 mice when compared with the controls (P = 0.001). However, p53−/−NOS2−/− mice did not show any difference in tumor latency between C. parvum–treated and control groups. In C. parvum–treated p53−/−NOS2+/+ mice, tumor development was preceded by a higher expression of NOS2 and phosphorylated Akt-Ser473 (pAkt-Ser473) in spleen, increased cell proliferation measured by Ki-67 IHC in spleen and thymus, and a lower apoptotic index and CD95-L expression in spleen and thymus. C. parvum–treated p53−/−NOS2+/+ mice showed an increase in the number of Foxp3(+) T-reg cells, dendritic cells (DC), as well as increased CD80+, CD86+, CD40+, and CD83+ on DC in the spleen. Regulatory T-cells (T-reg) and the maturation of DC may modulate tumorigenesis. An increase in the FoxP3(+)T-reg cells in C. parvum–treated p53−/−NOS2+/+ mice indicates a role of NO• in the regulation of T-reg cells that may contribute to a protumor shift of the immune environment favoring an accelerated tumor development. These data provide genetic and mechanistic evidence that an inflammatory microenvironment and an increased level of NO• can accelerate tumor development. [Cancer Res 2008;68(17):7130–6]

Background : The p53 tumor suppressor gene (also known as TP53) is often mutated in a wide variety of cancers, including angiosarcoma of the liver (ASL). Anti-p53 antibodies have been detected in the sera of patients with leukemia, childhood lymphoma, or cancers such as those of the breast, lung, colon, esophagus, and liver (hepatocellular carcinoma). Purpose : The objective of this study was to determine the prevalence and time of appearance of serum anti-p53 antibodies during the pathogenesis of ASL associated with occupational exposure to vinyl chloride. Methods : Enzyme-linked immunoassay (EIA) was used to detect anti-p53 antibodies in 148 serum samples from 92 individuals occupationally exposed (in France or in Kentucky) to vinyl chloride ; 15 of these individuals (six from France and nine from Kentucky) had ASL. A subset of coded EIA-positive and EIA-negative sera was further analyzed for anti-p53 antibodies by immunoblotting and immunoprecipitation. Nucleotide sequence analysis of exons 5-8 of the p53 gene was conducted on ASL DNA from six patients. We tested sera from 31 men who had no occupational exposure to vinyl chloride ; they made up the control group. Statistical analyses were done using the Kruskal-Wallis chisquared approximation and the Wilcoxon two-sample test for normal approximation. All P values result from two-sided tests. Results : Fourteen serum samples (from nine individuals) were positive in the EIA. Five of the 15 individuals with ASL were positive for anti-p53 antibodies by EIA, immunoblotting, and immunoprecipitation : one individual at 11.3 and 10.8 years before diagnosis, another at 4 months before and shortly after diagnosis, and three when diagnosed or shortly thereafter. Four of the 77 vinyl chloride-exposed workers without diagnosed ASL were positive for anti-p53 antibodies ; two of the four had symptoms related to vinyl chloride toxicity. Tumors from three of the six vinyl chloride-exposed workers from which sufficient DNA for analysis was obtained had A :T to T :A missense mutations of the p53 gene. Anti-p53 antibodies were detected in two of these individuals. Among the control group, two of 15 serum samples from 15 lung cancer patients and zero of 15 serum samples from control subjects without cancer had anti-p53 antibodies at substantially lower levels than the nine (10%) of 92 vinyl chloride-exposed workers who were positive for anti-p53 antibodies. Conclusions and Implications : Serum anti-p53 antibodies can predate clinical diagnosis of certain tumors, such as ASL, and may be useful in identifying individuals at high cancer risk, such as workers with occupational exposure to vinyl chloride.

Background : The lung cancer incidence in Chinese women is among the highest in the world, but tobacco smoking accounts for only a minority of the cancers. Epidemiologic investigations of lung cancer among Chinese women have implicated exposure to indoor air pollution from wok cooking, where the volatile emissions from unrefined cooking oils are mutagenic. Purpose : This study was conducted to identify and quantify the potentially mutagenic substances emitted from a variety of cooking oils heated to the temperatures typically used in wok cooking. Methods: Several cooking oils and fatty acids were heated in a wok to boiling, at temperatures (for the cooking oils) that ranged from 240 °C to 280 °C (typical cooking temperatures in Shanghai, China). The oils tested were unrefined Chinese rapeseed, refined U.S. rapeseed (known as canola), Chinese soybean, and Chinese peanut in addition to linolenic, linoleic, and erucic fatty acids. Condensates of the emissions were collected and tested in the Salmonella mutation assay (using Salmonella typhimurium tester strains TA98 and TA104). Volatile decomposition products also were subjected to gas chromatography and mass spectroscopy. Aldehydes were detected using high-performance liquid chromatography and UV spectroscopy. Results : 1,3-Butadiene, benzene, acrolein, formaldehyde, and other related compounds were qualitatively and quantitatively detected, with emissions tending to be highest for unrefined Chinese rapeseed oil and lowest for peanut oil. The emission of 1,3-butadiene and benzene was approximately 22-fold and 12-fold higher, respectively, from heated unrefined Chinese rapeseed oil than from heated peanut oil. Lowering the cooking temperatures or adding an antioxidant, such as butylated hydroxyanisole, before cooking decreased the amount of these volatile emissions. Among the individual fatty acids tested, heated linolenic acid produced the greatest quantities of 1,3-butadiene, benzene, and acrolein. Separately, the mutagenicity of individual volatile emission condensates was correlated with linolenic acid content (r =.83 ; P =.0004). Condensates from heated linolenic acid, but not linoleic or erucic acid, were highly mutagenic. Conclusions : These studies, combined with experimental and epidemiologic findings, suggest that high-temperature wok cooking with unrefined Chinese rapeseed oil may increase lung cancer risk. This study indicates methods that may reduce that risk. Implications : The common use of wok cooking in China might be an important but controllable risk factor in the etiology of lung cancer. In the United States, where cooking oils are usually refined for purity, additional studies should be conducted to further quantify the potential risks of such methods of cooking. [J Natl Cancer Inst 87 :836-841, 19951

Accumulating evidence suggests a role for inflammation in the development and progression of cancer. Our group recently identified a cytokine gene signature in lung tissue associated with lung cancer prognosis. Therefore, we hypothesized that concentrations of circulating cytokines in serum may be associated with lung cancer survival. Ten serum cytokines, namely, interleukin (IL)-1β, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12, granulocyte macrophage colony-stimulating factor, interferon (IFN)-γ, and tumor necrosis factor-α, were assessed in 353 non–small cell lung cancer cases from a case-control study of lung cancer in the greater Baltimore, Maryland area. Cytokines were measured using an ultrasensitive electrochemiluminescence immunoassay. IL-6 serum concentrations (≥4.0 pg/mL) were associated with significantly poorer survival in both African Americans [hazard ratio (HR), 2.71; 95% confidence interval (CI), 1.26-5.80] and Caucasians (HR, 1.71; 95% CI, 1.22-2.40). IL-10 (HR, 2.62; 95% CI, 1.33-5.15) and IL-12 (HR, 1.98; 95% CI, 1.14-3.44) were associated with lung cancer survival only in African Americans. Some evidence for an association of tumor necrosis factor-α levels with survival in Caucasians was observed, although these results were not significant. These hypothesis-generating findings indicate that selected serum cytokine concentrations are associated with lung cancer survival, and indicate that further research is warranted to better understand the mechanistic underpinnings of these associations. (Cancer Epidemiol Biomarkers Prev 2009;18(1):215–22)

In lung tumors, the p53 tumor suppressor gene is commonly mutated with a characteristic mutation spectrum. The amount of and alterations in plasma DNA, such as mutations in p53, were associated with several cancers. Few studies used quantitative methods of high sensitivity. Previously, we observed p53 mutations in the noncancerous tissue that differed from those in lung tumors using the highly sensitive p53 mutation load assay. Based on our observation of an increased p53 mutation load in nontumorous lung tissue in smokers, we hypothesized that plasma DNA may contain mutant p53 indicative of tobacco smoke exposure and will be an effective biomarker of lung cancer or smoking exposure. We modified the p53 mutation load assay to detect mutations at p53 codons 248 and 249, common mutations in lung cancer, in plasma DNA samples with a sensitivity of 1:5,000. The assay was applied to a set of lung cancer cases (n = 39), hospital controls (n = 21), and population controls (n = 20) from a larger study. Controls were selected to consist of equal numbers of both ever and never smokers. The p53 mutation load (mutated p53 copies per total number of p53 copies) was associated with smoking (P = 0.06), but not with lung cancer (P = 0.59). Most of the individuals with p53 mutations observed in plasma DNA were ever smokers and the p53 mutation load was higher in those who smoked for longer durations (P = 0.04). In summary, we were able to detect p53 mutations in plasma DNA from healthy individuals and our data suggest that p53 mutations in plasma DNA may be a marker of carcinogen exposure from tobacco smoke. (Cancer Res 2006; 66(16): 8309-17)

We previously discovered anti-p53 antibodies predating a cancer diagnosis in subjects at increased risk for liver, lung, breast, and prostate cancer. Recently, we reported a significant correlation (P0.017) between p53 antibodies and p53 mutations in patients with late-stage esophageal carcinoma. Because others have reported p53 mutations and overexpression of p53 protein in Barrett's esophagus, we studied p53 antibodies in plasma of 88 serially endoscoped patients: 36 with Barrett's metaplasia, 23 with esophageal squamous cell carcinoma, 10 with esophageal adenocarcinoma, and 19 with esophagitis or normal esophagus.We used enzyme immunoassay, immunoblotting, and immunoprecipitation assays for p53 antibodies; polymerase chain reaction, denaturant gradient gel electrophoresis, and sequencing for p53 mutations; and immunohistochemistry for p53 protein.p53 antibodies were detected in 4 patients with Barrett's esophagus, including 1 with dysplasia that later progressed to adenocarcinoma, and in 10 cancer patients (P = 0.002) (8 squamous and 2 adenocarcinoma), 2 of whom (1 squamous, 1 adenocarcinoma) had antibodies before cancer was diagnosed. Other patient groups were too small for informative statistical analysis. Six antibody-positive cancer patients had p53 mutations, whereas 2 patients with cancer and 1 with Barrett's esophagus with antibodies had p53 protein overexpressed in esophageal tissues.Patients with Barrett's esophagus and esophageal cancer can develop p53 antibodies that may predate the clinical diagnosis of malignancy.

Serum antibodies reacting with the tumor suppressor protein p53 have been detected previously in cancer patients with a variety of neoplasms. Two initial (although insufficient) prerequisites for a B-cell response to occur have been proposed: p53 protein accumulation in the tumor or a mutant p53 gene, or both. We have examined 65 esophageal cancer cases (42 from Guangzhou and Shenyang, People's Republic of China, and 23 from Paris, France) to obtain a prevalence estimate of anti-p53 antibodies for this type of cancer and to define the relationship of p53 tumor status to B-cell immune response. Sera were analyzed in a triplicate assay (enzyme-linked immunoassay, immunoprecipitation, and immunoblot) for anti-p53 antibodies. Tumor DNA was screened for mutations in exons 5-8, and tumor tissue was examined by immunohistochemistry for abnormal p53 protein accumulation. p53 mutations were found in 36 (58%) of 62 cases analyzed. Sixteen patients (25%) had circulating antibodies to the tumor suppressor protein. All but two (88%) of the tumors from seropositive cases had a mutation in the DNA binding region of the p53 gene, and with one exception, these tumors also showed nuclear accumulation of the p53 protein. In contrast, tumor mutations were found in just 22 (46%) of the 48 individuals in whom we did not detect anti-p53 antibodies. Among the 22 seronegative cases for which we found no tumor mutations, 11 revealed p53 protein accumulation by immunohistochemical analysis. Thus, circulating anti-p53 antibodies may be present in one-fourth of esophageal cancer patients, most of whom also would be expected to have a p53 gene mutation in their tumors. Patients without such mutations appear considerably less likely to mount a B-cell response to the p53 tumor suppressor protein than those that do (P0.01).

Serum anti-p53 antibodies (p53-Abs) may be surrogate markers for both p53 alterations and preclinical cancer. Ancillary to a prospective trial to abate progressive development of clinical stages of chronic obstructive pulmonary disease, we conducted a retrospective, nested case-control study. Twenty-three cases were diagnosed with cancer during the trial. Enzyme immunoassay, immunoblotting, and immunoprecipitation were used to detect p53-Abs in serum, immunohistochemistry (IHC) to detect p53 accumulation, and single-strand conformation polymorphism and DNA sequencing to detect p53 mutations in tumor samples. p53-Abs were detected by three types of assays in five (23%) of the cancer patients, 80% of whom had detectable p53-Abs before diagnosis: 2 lung cancers (7 and 6 months before), 1 prostate cancer (11 months), and 1 breast cancer (5 months). Four Ab-positive patients had IHC-positive tumors. Two of 4 Ab-positive patients and 2 of 14 Ab-negative had p53 missense mutations or base pair deletion and IHC-positive tumors. The 44 noncancer COPD controls, matched with the cancer cases for age, gender, and smoking habits, were negative for p53-Abs. These results indicate that p53-Abs may facilitate the early diagnosis of cancer in a subset of smokers with chronic obstructive pulmonary disease who are at an increased cancer risk.

The p53 tumor suppressor gene is commonly mutated in human hepatocellular carcinoma (HCC). The most frequent mutation in HCC in populations exposed to a high dietary intake of aflatoxin B1 (AFB1) is an AGGarg-->AGTser missense mutation in codon 249 of the p53 gene. We analyzed HCCs from Monterrey, Mexico, for the codon 249ser hotspot mutation. We also analyzed the serum AFB1-albumin adduct levels of the donors and family members to measure the current AFB1 exposure in this population. Moreover, the presence of hepatitis B and/or C viral infection (HBV or HCV) was analyzed serologically in the patients. Tumor cells were microdissected from tissue sections and exon 7 p53 sequences were amplified by polymerase chain reaction from genomic DNA and sequenced directly. The serological tests for anti-p53 antibodies, HBV or HCV were done by ELISA. Immunohistochemical analysis of p53 protein was done using a polyclonal rabbit antiserum (CM-1). Eight of 21 cases were positive by p53 immunohistochemistry. Of the 16 cases sequenced for exon 7 of p53 three codon 249 AGGarg-->AGTser mutations were found. Serum antibodies recognizing p53 protein were found in one of 18 patients. Positive serology for HBV and/or HCV was found in 12 of 20 cases. The serum AFB1-albumin adduct levels in this population ranged from 0.54 to 4.64 pmol aflatoxin/mg albumin. These results indicate that dietary AFB1 and hepatitis viruses are etiological agents in the molecular pathogenesis of HCC in this geographic region of Mexico.

Little is known about the molecular mechanisms of lung carcinogenesis in women. We initiated an investigation of the role of gender in pulmonary carcinogenesis by analysis of p53 mutations, immunohistochemistry, serum antibodies and c-erbB-2 expression in a series of 63 male and 44 female lung cancer patients whose tumors were resected at the Mayo Clinic between 1991 and 1992. There were 102 smokers and 5 never smoked. Adenocarcinoma was the more frequent histological type in women (62%) than in men (41%). Sequence analysis of exons 5-8 in 42 females and 49 males identified 44 p53 mutations in 42 tumors (46%). Base substitution mutations showed a preponderance of G:C-->T:A transversions, which were more frequent in women than men (40 versus 25%) and in individuals exposed to asbestos. c-erbB-2 immunohistochemical staining was identified more frequently in females (nine cases) than males (two cases). Marked immunohistochemical staining for p53 positively correlated with the presence of missense mutations in exons 5-8 (81%, P < 0.001). Seven missense mutations (four in exon 5, two in exon 6, one in exon 8) were identified in five of nine patients who had serum antibodies recognizing p53; tumors from these patients were also strongly positive for p53 by immunohistochemistry. These and other results indicate gender differences in the genetic and biochemical alterations in lung cancer and generate hypothesis regarding gender differences in lung cancer susceptibility.

Hepatocellular carcinoma is common among Alaska Natives. The known risk factor in this population is hepatitis B viral infection; fungal toxins, including aflatoxin B1, have not been detected in foodstuffs. In this series of 14 patients (including 4 siblings and 2 second cousins), 3 patients were less than 12 years old at diagnosis of hepatocellular carcinoma, 8 patients were 13-24 years old, and 3 patients were more than 60 years old. Since p53 mutations occur in 29% of hepatocellular carcinomas worldwide, we tested the tumors for p53 mutations and serum samples for anti-p53 antibodies. Serum samples from these 14 patients did not contain detectable levels of anti-p53 antibodies. Loss of heterozygosity within the p53 locus was not detected in any of 9 informative cases. Immunohistochemical analysis for p53 protein accumulation was negative in all of 11 tumors. DNA sequence analysis of 12 tumor samples showed no evidence of p53 mutation in the highly conserved regions included in exons 5-8. These data, combined with one case from a previous report, indicate a mutation frequency of 0 of 13, which differs significantly from the worldwide frequency of 29% (chi 2 3.9; P = 0.048). These results indicate that liver carcinogenesis among Alaska Natives occurs independently of a traditional p53 pathway. The familial clustering and early onset in this population strongly suggest an inherited genetic predisposition to develop liver cancer. Germline mutations in a tumor suppressor or a cancer susceptibility gene are likely. Future studies of these samples should include investigations of candidate suppressor or susceptibility genes which map to chromosomal regions commonly deleted in liver cancers.

Human cancer risk assessment using molecular genetic techniques is a rapidly emerging field. Many studies suggest that both inherited and acquired genetic predispositions play an important role in carcinogenesis. Cytochrome P450 (CYP) 2E1 is involved in the metabolic activation of N-nitrosamines and other low molecular weight compounds. A recently described genetic polymorphism of CYP2E1 [DraI restriction fragment length polymorphism (RFLP)] has been associated with an increased risk of lung cancer in Japanese. We have assessed the allelic frequency of three RFLPs (PstI, RsaI, and DraI) in African-Americans (n = 109), Caucasian Americans (n = 153), and octogenarian Japanese (n = 42), and also in a United States case-control study of lung cancer (histologically confirmed lung cancer, n = 58; controls, n = 56; total, n = 114). The relationship of the CYP2E1 DraI polymorphism to other CYP2E1 polymorphisms (PstI and RsaI RFLP) was examined. The allelic frequency of the DraI C minor allele for all subjects was 0.09 in Caucasians, 0.09 in African-Americans, and 0.31 in Japanese. In the case-control study of lung cancer, no association of the CYP2E1 DraI genotype with lung cancer was found (odds ratio, 1.57; 95% confidence interval, 0.59-4.18). Comparison after discordant CYP2E1 genotypes suggests the presence of different haplotypes in Americans and Japanese. These results indicate that the CYP2E1 DraI RFLP is probably not a cancer risk factor in United States Caucasian or African-Americans, although statistical power is limited given the low frequency of the CYP2E1 DraI C minor alleles.

The assessment of human cancer risk using molecular epidemiological techniques involves determining the relative contributions of inherited and acquired genetic predispositions, in the context of environmental exposures. Recently described genetic polymorphisms for CYP1A1, a gene involved in the metabolic activation of polycyclic aromatic hydrocarbons, have been associated with lung cancer risk in a Japanese population. We report herein findings from a United States case-control study of lung cancer (56 cases; 48 controls). The polymerase chain reaction followed by an Msp1 restriction enzyme digestion was used to analyze constitutive DNA but no association between the restriction fragment length polymorphism and lung cancer risk was found (odds ratio, 0.7; 95% confidence interval, = 0.3-1.6). Analysis of genotype by cumulative smoking status did not reveal an elevated risk among lesser or greater smokers. The presence of the CYP1A1 Msp1 site-present allele, which was previously found to be associated with Japanese lung cancer risk, was statistically increased in African compared to Caucasian Americans (odds ratio, 2.9; 95% confidence interval, 1.2-2.7). When stratified by race, however, no association between case status and the polymorphism was observed, but the small number of study subjects within each racial group limited the statistical power. Larger studies are required to evaluate the risk of the CYP1A1 Msp1 polymorphism in African Americans.

ING2 (inhibitor of growth family, member 2) is a member of the plant homeodomain (PHD)-containing ING family of putative tumor suppressors. As part of mSin3A-HDAC corepressor complexes, ING2 binds to tri-methylated lysine 4 of histone H3 (H3K4me3) to regulate chromatin modification and gene expression. ING2 also functionally interacts with the tumor suppressor protein p53 to regulate cellular senescence, apoptosis and DNA damage response in vitro, and is thus expected to modulate carcinogenesis and aging. Here we investigate the developmental and physiological functions of Ing2 through targeted germline disruption. Consistent with its abundant expression in mouse and human testes, male mice deficient for Ing2 showed abnormal spermatogenesis and were infertile. Numbers of mature sperm and sperm motility were significantly reduced in Ing2(-/-) mice (∼2% of wild type, P3-fold reduction) and in testes from patients with defective spermatogenesis (>7-fold reduction in Sertoli-cell only Syndrome). This study establishes ING2 as a novel regulator of spermatogenesis functioning through both p53- and chromatin-mediated mechanisms, suggests that an HDAC1/ING2/H3K4me3-regulated, stage-specific coordination of chromatin modifications is essential to normal spermatogenesis, and provides an animal model to study idiopathic and iatrogenic infertility in men. In addition, a bona fide tumor suppressive role of Ing2 is demonstrated by increased incidence of soft-tissue sarcomas in Ing2(-/-) mice.

ING2 (inhibitor of growth family, member 2) plays pivotal roles in the regulation of cellular senescence, apoptosis, DNA damage repair, gene transcription and chromatin modification. Our previous in vitro studies on cellular senescence suggested that ING2 functionally interplays with the p53 tumor suppressor protein in two different manners: endogenous ING2 inhibits senescence and the transcriptional repression of ING2 by p53 abrogates this inhibition; and overexpressed ING2 enhances p53 acetylation and stability to induce senescence. ING2, as a subunit of the mSin3A-HDAC1 (histone deacetylase 1) complex, specifically binds to tri-methylated lysine 4 of histone H3 (H3K4me3) via its plant homeodomain (PHD) finger and regulates gene expression through chromatin modifications in response to DNA damage. This study investigates the in vivo developmental and physiological functions of ING2. Abundant expression of ING2 in mouse and human testes and its decreased expression associated with male infertility and defective spermatogenesis in humans suggested an essential role of ING2 in spermatogenesis, which is a process tightly regulated by chromatin modifications. Consistently, male mice deficient for Ing2 were infertile. Their testes had degeneration of seminiferous tubules, which became more severe with age, and showed enhanced p53-dependent and -independent apoptosis. Spermatogenesis arrest at meiotic phase in Ing2−/− testes was due to impaired HDAC1 accumulation and deregulated chromatin acetylation. This study establishes ING2 as a novel mammalian regulator of spermatogenesis, suggests that an HDAC1/ING2/H3K4me3-regulated, stage-specific coordination of chromatin modifications is essential to normal spermatogenesis, and provides a model system to study idiopathic and iatrogenic infertility in men, including those who had cancer chemotherapy and radiotherapy. Spontaneous tumor incidence and spectrum were similar in wild-type and Ing2-deficient mice. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4890.

There is sufficient evidence that the use of tobacco is carcinogenic to humans. Epidemiological studies have shown that tobacco smoking is the primary cause of lung cancer and that organs other than lung are at high risk, such as bladder, pancreas, oral cavity, upper digestive and respiratory tract. A number of carcinogens, mutagens and tumor promoters, have been identified in tobacco smoke.

Human placenta is a readily available organ that responds to maternal environmental insult and has been previously used to investigate metabolism and bioactivation of procarcinogens, for example, benzo[a]pyrene. HPLC in combination with synchronous fluorescence spectroscopy was used to examine 28 placentas for the presence of benzo[a]pyrene diol epoxide-DNA adducts, and 10 of these were found to be positive. DNA samples from these placentas were subsequently pooled and subjected to partial enzymatic digestion to oligonucleotide fragments. Concentration of those DNA fragments containing benzo[a]pyrene diol epoxide-DNA adducts was achieved by immunoaffinity chromatography with polyclonal antibodies raised against these adducts. Column eluates were hydrolyzed under mild acid conditions and extracted with an organic solvent. The presence of benzo[a]pyrene-7,10/8,9-tetrahydrotetrol residues in the extracts was determined by HPLC and synchronous fluorescence spectroscopy and was confirmed by GC/MS. The results unequivocally confirm bioactivation and formation of DNA adducts from benzo[a]pyrene in human placenta in vivo and establish a methodological approach to direct measurement of carcinogen-DNA adducts that are formed as a result of human environmental exposure.

Metabolic activation in humans of chemical carcinogens found in the environment results in the formation of carcinogen-DNA adducts in vivo. Some polycyclic aromatic hydrocarbon-DNA adducts in human DNA can be hydrolyzed under mildly acidic conditions to yield tetrahydrotetrol derivatives which may then be detected by synchronous fluorescence spectroscopy. In an analysis of human placental DNA, second derivative spectroscopy alone was unable to resolve the synchronous fluorescent signature for r-7,t-8,t-9,c-10-tetrahydroxy-7,8,9,10-tetrahydrobenzo[alpha]pyrene from a crude extract, because a complex array of other fluorescent materials was also present. Purification of the sample by a combination of chromatographic procedures including immunoaffinity chromatography and HPLC has now been shown to yield r-7,t-8,t-9,c-10-tetrahydroxy-7,8,9,10-tetrahydrobenzo[alpha]pyrene residues from human DNA that are spectroscopically pure at the second derivative level. Immunoaffinity columns were prepared with rabbit antiserum raised against DNA that had been modified with (+/-)-r-7,t-8-dihydroxy-t-9,10-epoxy-7,8,9,10-tetrahydrobenzo[alpha]pyre ne. This antiserum has now been shown to recognize DNA samples that have been modified with six different polycyclic aromatic hydrocarbon diol epoxides and is probably only specific for a broad spectrum of polycyclic aromatic hydrocarbon-DNA adducts. Adducts were eluted from the immunoaffinity columns, hydrolyzed with acid, and extracted into isoamyl alcohol, before being subjected to high-performance liquid chromatography. These experiments reveal important limitations of second derivative fluorescence spectroscopy as a tool in the analysis of complex environmental mixtures. Furthermore, they extensively define the ability of anti-benzo[alpha]pyrenediol epoxide-DNA antibodies to recognize different types of polycyclic aromatic hydrocarbon-DNA adducts.

Workers in coke oven plants have a higher incidence of lung cancer than the general population. They are exposed to a variety of chemicals, in particular the polycyclic aromatic hydrocarbons (PAH), including benzo(a)pyrene. To evaluate the genotoxic effects of PAH exposure, air samples and urine samples were analyzed for PAH by capillary gas chromatography and high-performance liquid chromatography, respectively. Since benzo(a)pyrene is activated to 7 beta,8 alpha-dihydroxy-(9 alpha,10 alpha)-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene (BPDE) and binds to DNA, we have used ultrasensitive enzymatic radioimmunoassay and synchronous fluorescence spectrophotometry to measure BPDE-DNA adducts in lymphocyte DNA. The results show that workers were exposed to high concentrations of atmospheric PAH. However, the mean PAH exposure levels are reduced 60% when the workers wore masks during work. When compared to exposure levels, the urinary excretion of PAH was relatively low. Approximately one-third of the workers had detectable putative BPDE-DNA adducts in lymphocytes by ultrasensitive enzymatic radioimmunoassay, and 10% of the samples had emission peaks at 379 nm by synchronous fluorescence spectrophotometry. The four most positive samples were the same in both of the assays. Antibodies to an epitope(s) on BPDE-DNA were found in the sera of approximately one-third of the workers. Detection of DNA adducts and antibodies to these adducts are internal indicators of exposure to benzo(a)pyrene.

The metabolic activation of polycyclic aromatic hydrocarbons (PAH), for example benzo[a]pyrene, leads to the formation of carcinogen-macromolecular adducts. Methods that make it possible to detect low levels of these adducts in human peripheral blood samples should be useful in the dosimetry of human exposure to carcinogens. We demonstrated previously the usefulness of enzyme immunoassays and of synchronous fluorescence spectroscopy (SFS) for detecting and characterizing low levels of PAH-macromolecular adducts present in synthetic adduct mixtures. These methods have now been refined and applied to the analysis of samples of peripheral blood collected from occupationally exposed individuals (coke-oven workers) and from people attending smoking cessation clinics. The results of both immunoassays and SFS show the presence of benzo[a]pyrene diol epoxide (BPDE)-DNA, BPDE-haemoglobin and other putative PAH-macromolecular adducts in peripheral blood samples from certain individuals.

Human peripheral lung tissue samples were obtained at autopsy from 17 individuals of known occupational and smoking histories. A spectrum of different carcinogen-DNA adducts was detected using a variety of sensitive techniques. High-pressure liquid chromatography-linked synchronous fluorescent spectrophotometry and an ultrasensitive enzyme radioimmunoassay detected adducts derived from benzo[a]pyrene diol epoxide and other apparent polycyclic aromatic hydrocarbons. An amplified enzyme-linked immunosorbent assay demonstrated the presence of 4-aminobiphenyl-DNA adducts in many of these samples. A number of these specimens also contained O6-alkyldeoxyguanosine as measured by 32P-postlabeling techniques. Thus this pilot study indicates not only that human lung contains a spectrum of carcinogen-DNA adducts, but also that a full scale molecular dosimetry study of human exposure to both aryl and alkyl chemical carcinogens is warranted.