Newly diagnosed patients with advanced non-small cell lung cancer: A clinical description of those with moderate to severe depressive symptoms

OBJECTIVES

The aims of this observational study were to 1) accrue newly diagnosed patients with advanced-stage non-small cell lung cancer (NSCLC) awaiting the start of first-line treatment and identify those with moderate to severe depressive symptoms and, 2) provide a clinical description of the multiple, co-occurring psychological and behavioral difficulties and physical symptoms that potentially exacerbate and maintain depressive symptoms.

MATERIALS AND METHODS

Patients with stage IV NSCLC (N = 186) were enrolled in an observational study (ClinicalTrials.gov Identifier: NCT03199651) and completed the American Society of Clinical Oncology-recommended screening measure for depression (Patient Health Questionnaire-9 [PHQ-9]). Individuals with none/mild (n = 119; 64 %), moderate (n = 52; 28 %), and severe (n = 15; 8 %) depressive symptoms were identified. Patients also completed measures of hopelessness, generalized anxiety disorder (GAD) symptoms, stress, illness perceptions, functional status, and symptoms.

RESULTS

Patients with severe depressive symptoms reported concomitant feelings of hopelessness (elevating risk for suicidal behavior), anxiety symptoms suggestive of GAD, and traumatic, cancer-specific stress. They perceived lung cancer as consequential for their lives and not controllable with treatment. Pain and multiple severe symptoms were present along with substantial functional impairment. Patients with moderate depressive symptoms had generally lower levels of disturbance, though still substantial. The most salient differences were low GAD symptom severity and fewer functional impairments for those with moderate symptoms.

CONCLUSIONS

Depressive symptoms of moderate to severe levels co-occur in a matrix of clinical levels of anxiety symptoms, traumatic stress, impaired functional status, and pain and other physical symptoms. All of the latter factors have been shown, individually and collectively, to contribute to the maintenance or exacerbation of depressive symptoms. As life-extending targeted and immunotherapy use expands, prompt identification of patients with moderate to severe depressive symptoms, referral for evaluation, and psychological/behavioral treatment are key to maximizing treatment outcomes and quality of life for individuals with advanced NSCLC.

Single nucleotide polymorphisms in uracil-processing genes, intake of one-carbon nutrients and breast cancer risk

BACKGROUND/OBJECTIVES

The misincorporation of uracil into DNA leads to genomic instability. In a previous study, some of us identified four common single nucleotide polymorphisms (SNPs) in uracil-processing genes (rs2029166 and rs7296239 in SMUG1, rs34259 in UNG and rs4775748 in DUT) that were associated with significantly altered levels of uracil in human DNA. We investigated whether any of these SNPs are associated with an altered risk of developing breast cancer and if one-carbon nutrients intake can modify their effects.

SUBJECTS/METHODS

We genotyped the four SNPs in 1077 cases of incident breast cancer and 1910 age and race-matched controls in the Western New York Exposures and Breast Cancer (WEB) Study and examined associations with breast cancer risk and interactions with intake of folate, vitamins B6 and B12.

RESULTS

After adjustment for known risk factors for breast cancer, there was increased risk of breast cancer among postmenopausal women who were heterozygous for either of the two SMUG1 SNPs (odds ratio (OR) 1.29, 95% confidence interval (CI) 1.07-1.56) and OR 1.29, 95% CI 1.07-1.55, respectively). Among premenopausal women, increased risk associated with the SMUG1 rs2029166 genotype was limited to those with low folate intake. There were no other interactions with vitamins B(6) or B(12) intake.

CONCLUSIONS

Our study suggests that the four selected SNPs are not robust determinants of breast cancer risk, but that the two SNPs in SMUG1 might modestly alter the risk of breast cancer. However, the increase in risk among heterozygotes in the two SNPs in SMUG1, which is thought to be the most active glycosylase in vivo, raises the possibility that subtle 'heterosis' effects on cancer risk might be produced by these SNPs.

Familial and racial determinants of tumour suppressor genes promoter hypermethylation in breast tissues from healthy women

To determine the hypermethylation status of the promoter regions of tumour suppressor genes in breast tissues from healthy women and identify the determinants of these epigenetic changes. Questionnaires and breast tissues were collected from healthy women without a history of cancer and undergoing reduction mammoplasty (N= 141). Methylation for p16^INK4, BRCA1, ERα and RAR-β promoter regions from breast tissues were determined by methylation specific PCR. Associations were examined with chi-square and Fisher’s exact test as well as logistic regression. All statistical tests were two-sided. p16^INK4, BRCA1, ERα and RAR-β hypermethylation were identified in 31%, 17%, 9% and 0% of the women, respectively. Women with BRCA1 hypermethylation had an eight-fold increase in the risk of ERα hypermethylation (P= 0.007). p16^INK4 hypermethylation was present in 28% of African-Americans, but 65% in European-Americans (P= 0.02). There was an increased likelihood of p16^INK4 or BRCA1 hypermethylation for women with family history of cancer (OR 2.3; 95%CI: 1.05–4.85 and OR 5.0; 95%CI: 1.55–15.81, respectively). ERα hypermethylation was associated with family history of breast cancer (OR 6.6; 95%CI: 1.58–27.71). After stratification by race, p16^INK4 in European-Americans and BRCA1 hypermethylation in African-Americans were associated with family history of cancer (OR 3.8; 95%CI: 1.21–12.03 and OR 6.5; 95%CI: 1.33–31.32, respectively). Gene promoter hypermethylation was commonly found in healthy breast tissues from women without cancer, indicating that these events are frequent and early lesions. Race and family history of cancer increase the likelihood of these early events.

Pathological confirmation of primary lung cancer following breast cancer

PURPOSE

Studies have shown that women who survive breast cancer have an increased risk of a future primary lung cancer, though many are based only on data recorded in tumor registries and none have conducted pathological confirmation. Previous studies and future use of large registries may be affected by misdiagnosis.

METHODS

Pathological analysis was conducted on tumors from 110 women with breast cancer followed by lung cancer using morphology, Estrogen Receptor-alpha (ER), and Thyroid Transcription Factor-1 (TTF1). We developed an algorithm to classify lung tumors as unlikely lung cancer (score=1) to likely lung cancer (score=5).

RESULTS

Mean time to diagnosis of lung cancer after breast cancer was 13 years. 76% of breast tumors and 20% of lung tumors were positive for ER and 51% of lung tumors were positive for TTF-1. 86% of the lung tumors were probable primaries, 7% were probable metastases from the breast, and 7% were of undetermined status. 70% of probable metastases had a latency of longer than 10 years.

CONCLUSION

Prior studies identifying the association of breast cancer and breast cancer treatments with lung cancer are likely to reflect true associations not confounded by misdiagnosis, as evidenced by the low rate of misclassification detected in this study. Analysis of the years of diagnosis suggests that latency may not be an accurate criterion for assignment of primary status, which could be significant in a clinical setting. These data may also benefit future retrospective studies using large registries.

Meta- and pooled analysis of GSTT1 and lung cancer: a HuGE-GSEC review

Lung cancer is the most common malignancy in the Western world, and the main risk factor is tobacco smoking. Polymorphisms in metabolic genes may modulate the risk associated with environmental factors. The glutathione S-transferase theta 1 gene (GSTT1) is a particularly attractive candidate for lung cancer susceptibility because of its involvement in the metabolism of polycyclic aromatic hydrocarbons found in tobacco smoke and of other chemicals, pesticides, and industrial solvents. The frequency of the GSTT1 null genotype is lower among Caucasians (10-20%) than among Asians (50-60%). The authors present a meta- and a pooled analysis of case-control, genotype-based studies that examined the association between GSTT1 and lung cancer (34 studies, 7,629 cases and 10,087 controls for the meta-analysis; 34 studies, 7,044 cases and 10,000 controls for the pooled analysis). No association was observed between GSTT1 deletion and lung cancer for Caucasians (odds ratio (OR) = 0.99, 95% confidence interval (CI): 0.87, 1.12); for Asians, a positive association was found (OR = 1.28, 95% CI: 1.10, 1.49). In the pooled analysis, the odds ratios were not significant for either Asians (OR = 0.97, 95% CI: 0.83, 1.13) or Caucasians (OR = 1.09, 95% CI: 0.99, 1.21). No significant interaction was observed between GSTT1 and smoking on lung cancer, whereas GSTT1 appeared to modulate occupational-related lung cancer.

The functional mu opioid receptor (OPRM1) Asn40Asp variant predicts short-term response to nicotine replacement therapy in a clinical trial

To determine whether the functional mu-opioid receptor (OPRM1) Asn40Asp variant predicts the comparative efficacy of different forms of NRT, we conducted a clinical trial of transdermal nicotine (TN) vs nicotine nasal spray (NS) in 320 smokers of European ancestry. Smokers carrying the OPRM1 Asp40 variant (n=82) were significantly more likely than those homozygous for the Asn40 variant (n=238) to be abstinent at the end of treatment, and reported less mood disturbance and weight gain. The genotype effect on treatment outcome was most pronounced among smokers receiving TN, particularly during the 21 mg dose phase. Smokers who carry the OPRM1 Asp40 variant are likely to have a favorable response to TN and may benefit from extended therapy with the 21 mg dose.

Lung cancer risks in women with previous breast cancer

Evaluation of the adverse effects of breast cancer treatment is becoming increasingly important in light of the earlier detection and prolonged survival of the patients. The beneficial effect of post-surgical radiotherapy has lately been challenged. The Swedish Cancer Registry (SCR) was used to identify approximately 141000 women with breast cancer, diagnosed between 1958 and 1997, followed-up for the occurrence of lung cancer. Standardised incidence ratios and expected number of lung cancers were calculated using incidence rates from the SCR. There were 613 subsequent lung cancers and a statistically significant increased risk of lung cancer was seen >5 years after breast cancer diagnosis, in contrast to a significantly decreased risk the first five years after the breast cancer diagnosis. The latter finding was confined to those >60 years of age when diagnosed with breast cancer. When restricting the analyses to those cases with information on the laterality of breast and lung cancer, an increased risk of a lung cancer on the same side as the breast cancer was seen >10 years after the breast cancer diagnosis. Birth cohorts with a higher smoking prevalence, i.e. 1930-1949, revealed a higher risk of lung cancer, than previous birth cohorts. Women with breast cancer have a significantly increased risk of developing a subsequent lung cancer possibly related to an interaction between radiotherapy and smoking.

Metabolic gene polymorphism frequencies in control populations

Using the International Project on Genetic Susceptibility to Environmental Carcinogens (GSEC) database containing information on over 15,000 control (noncancer) subjects, the allele and genotype frequencies for many of the more commonly studied metabolic genes (CYP1A1, CYP2E1, CYP2D6, GSTM1, GSTT1, NAT2, GSTP, and EPHX) in the human population were determined. Major and significant differences in these frequencies were observed between Caucasians (n = 12,525), Asians (n = 2,136), and Africans and African Americans (n = 996), and some, but much less, heterogeneity was observed within Caucasian populations from different countries. No differences in allele frequencies were seen by age, sex, or type of controls (hospital patients versus population controls). No examples of linkage disequilibrium between the different loci were detected based on comparison of observed and expected frequencies for combinations of specific alleles.

Smoking increases carcinogenic polycyclic aromatic hydrocarbons in human lung tissue

Tobacco smoke is a major source of human exposure to polycyclic aromatic hydrocarbons (PAHs). The concentration of PAHs in lung tissue would reflect an individual's dose, and its variation could perhaps reflect cancer risk. Eleven PAHs were measured in 70 lung tissue samples from cancer-free autopsy donors by gas chromatography-mass spectrometry. There were 37 smokers and 33 nonsmokers as estimated by serum cotinine concentration. The sum of PAH concentrations was higher in smokers (P = 0.01), and there was a dose-response relationship for greater smoking (P < 0.01). Smoking increased the concentration of five PAHs including benzo(a)pyrene, which increased approximately 2-fold. The risk for increasing carcinogenic PAHs (odds ratio, 8.20; 95% confidence interval, 2.39-28.09) was 3-fold compared with noncarcinogenic PAHs (odds ratio, 2.61; 95% confidence interval, 0.75-9.12). A higher concentration of PAHs was detected in the lung tissue of males, although the estimated smoking was similar in males and females. Race was not associated with PAH concentrations overall, but PAH concentrations appeared to be higher in African-American males than in any other group. Age was weakly correlated with an increase in fluoranthene and pyrene. The measurement of PAHs in human lung tissue can be used to estimate the actual dose to the target organ.

Mutability of p53 hotspot codons to benzo(a)pyrene diol epoxide (BPDE) and the frequency of p53 mutations in nontumorous human lung

p53 mutations are common in lung cancer. In smoking-associated lung cancer,the occurrence of G:C to T:A transversions at hotspot codons, e.g., 157, 248, 249,and 273, has been linked to the presence of carcinogenic chemicalsin tobacco smoke including polycyclic aromatic hydrocarbons suchas benzo(a)pyrene (BP). In the present study, we have used a highly sensitive mutation assay to determine the p53 mutation load in nontumorous human lung and to study the mutability of p53 codons 157, 248, 249, and 250 to benzo(a)pyrene-diol-epoxide (BPDE), an active metabolite of BP in human bronchial epithelial BEAS-2B cells. We determined the p53 mutational load at codons 157, 248, 249, and 250 in nontumorous peripheral lung tissue either from lung cancer cases among smokers or noncancer controls among smokers and nonsmokers. A 5-25-fold higher frequency of GTC(val) to TTC(phe) transversions at codon 157 was found in nontumorous samples (57%) from cancer cases (n = 14) when compared with noncancer controls (n = 8; P < 0.01). Fifty percent (7/14) of the nontumorous samples from lung cancer cases showed a high frequency of codon 249 AGG(arg) to AGT(ser) mutations (P < 0.02). Four of these seven samples with AGT(ser) mutations also showed a high frequency of codon 249 AGG(arg) to ATG(met) mutations, whereas only one sample showed a codon 250 CCC to ACC transversion. Tumor tissue from these lung cancer cases (38%) contained p53 mutations but were different from the above mutations found in the nontumorous pair. Noncancer control samples from smokers or nonsmokers did not contain any detectable mutations at codons 248, 249, or 250. BEAS-2B bronchial epithelial cells exposed to doses of 0.125, 0.5, and 1.0 microM BPDE, showed G:C to T:A transversions at codon 157 at a frequency of 3.5 x 10(-7), 4.4 x 10(-7), and 8.9 x 10(-7), respectively. No mutations at codon 157 were found in the DMSO-treated controls. These doses of BPDE induced higher frequencies, ranging from 4-12-fold, of G:C to T:A transversions at codon 248, G:C to T:A transversions and G:C to A:T transitions at codon 249, and C:G to T:A transitions at codon 250 when compared with the DMSO-treated controls. These data are consistent with the hypothesis that chemical carcinogens such as BP in cigarette smoke cause G:C to T:A transversions at p53 codons 157, 248, and 249 and that nontumorous lung tissues from smokers with lung cancer carry a high p53 mutational load at these codons.

Tryptophan hydroxylase gene variant and smoking behavior

Approximately 50% of the variance in smoking behavior is attributable to genetic factors. Genes in the serotonin system are plausible candidates because of serotonin's role in mood regulation. The present study examined the association of smoking behavior with a polymorphism in the TPH gene, which codes for a rate limiting enzyme in the biosynthesis of serotonin. A polymorphism in intron 7 has been linked with a variety of traits involving poor impulse control. Participants in this study were 249 Caucasian smokers and 202 nonsmokers recruited through newspaper advertisements. Smokers completed smoking history and nicotine dependence assessments. The overall frequencies of the A- and C-allele were 42% and 58%, respectively. There was no association of TPH alleles with smoking status. However, case series analysis indicated that individuals with the A/A genotype started smoking at age 15.6 years, compared with 17.3 years among smokers with other genotypes. This association was significant in a multivariate regression model controlling for age, education, body mass index (BMI), alcohol use, and medication use. This finding is consistent with previous studies relating the A-allele to impulsive behavior and suggests that it may predispose to early smoking initiation. Future family-based studies are needed to confirm this finding. Published 2001 Wiley-Liss, Inc.

Genetic polymorphisms in DNA repair genes and risk of lung cancer

Polymorphisms in DNA repair genes may be associated with differences in the repair efficiency of DNA damage and may influence an individual's risk of lung cancer. The frequencies of several amino acid substitutions in XRCC1 (Arg194Trp, Arg280His and Arg399Gln), XRCC3 (Thr241Met), XPD (Ile199Met, His201Tyr, Asp312Asn and Lys751Gln) and XPF (Pro379Ser) genes were studied in 96 non-small-cell lung cancer (NSCLC) cases and in 96 healthy controls matched for age, gender and cigarette smoking. The XPD codon 312 Asp/Asp genotype was found to have almost twice the risk of lung cancer when the Asp/Asn + Asn/Asn combined genotype served as reference [odds ratio (OR) 1.86, 95% confidence interval (CI), 1.02-3.40]. In light cigarette smokers (less than the median of 34.5 pack-years), the XPD codon 312 Asp/Asp genotype was more frequent among cases than in controls and was associated with an increased risk of NSCLC. Compared with the Asn/Asn carriers, the OR in light smokers with the Asp/Asn genotype was 1.70 (CI0.35 0.43-6.74) and the OR in those with the Asp/Asp genotype was 5.32 (CI0.35-21.02) (P trend = 0.01). The 312 Asp/Asp genotype was not associated with lung cancer risk in never-smokers or heavy smokers (>34.5 pack-years). The XPD-312Asp and -751Lys polymorphisms were in linkage disequilibrium in the group studied; this finding was further supported by pedigree analysis of four families from Utah. The XPD 312Asp amino acid is evolutionarily conserved and is located in the seven-motif helicase domain of the RecQ family of DNA helicases. Our results indicate that these polymorphisms in the XPD gene should be investigated further for the possible attenuation of DNA repair and apoptotic functions and that additional molecular epidemiological studies are warranted to extend these findings.

Increased p53 mutation load in nontumorous human liver of wilson disease and hemochromatosis: oxyradical overload diseases

Hemochromatosis and Wilson disease (WD), characterized by the excess hepatic deposition of iron and copper, respectively, produce oxidative stress and increase the risk of liver cancer. Because the frequency of p53 mutated alleles in nontumorous human tissue may be a biomarker of oxyradical damage and identify individuals at increased cancer risk, we have determined the frequency of p53 mutated alleles in nontumorous liver tissue from WD and hemochromatosis patients. When compared with the liver samples from normal controls, higher frequencies of G:C to T:A transversions at codon 249 (P < 0.001) and C:G to A:T transversions and C:G to T:A transitions at codon 250 (P < 0.001 and P < 0.005) were found in liver tissue from WD cases, and a higher frequency of G:C to T:A transversions at codon 249 (P < 0.05) also was found in liver tissue from hemochromatosis cases. Sixty percent of the WD and 28% of hemochromatosis cases also showed a higher expression of inducible nitric oxide synthase in the liver, which suggests nitric oxide as a source of increased oxidative stress. A high level of etheno-DNA adducts, formed from oxyradical-induced lipid peroxidation, in liver from WD and hemochromatosis patients has been reported previously. Therefore, we exposed a wild-type p53 TK-6 lymphoblastoid cell line to 4-hydroxynonenal, an unsaturated aldehyde involved in lipid peroxidation, and observed an increase in G to T transversions at p53 codon 249 (AGG to AGT). These results are consistent with the hypothesis that the generation of oxygen/nitrogen species and unsaturated aldehydes from iron and copper overload in hemochromatosis and WD causes mutations in the p53 tumor suppressor gene.

Increased p53 mutation load in noncancerous colon tissue from ulcerative colitis: a cancer-prone chronic inflammatory disease

Ulcerative colitis (UC) is a chronic inflammatory disease that produces reactive oxygen and nitrogen species and increases the risk of colorectal cancer (CRC). The p53 tumor suppressor gene is frequently mutated in UC-associated dysplastic lesions and CRC. We are exploring the hypothesis that p53 mutations in the nontumorous colonic tissue in noncancerous UC cases indicate genetic damage from exposure to exogenous and endogenous carcinogens and may identify individuals at increased cancer risk. We are reporting, for the first time, the frequency of specific p53 mutated alleles in nontumorous colon tissue from donors either with or without UC by using a highly sensitive genotypic mutation assay. Higher p53 mutation frequencies of both G:C to A:T transitions at the CpG site of codon 248 and C:G to T:A transitions at codon 247 were observed in colon from UC cases when compared with normal adult controls (P = 0.001 and P = 0.001, respectively). In the UC cases, higher p53 codon 247 and 248 mutation frequencies were observed in the inflamed lesional regions when compared with the nonlesional regions of their colon (P < 0.001 and P = 0.001). The colonic nitric oxide synthase-2 activity was higher in UC cases than in non-UC adult controls (P = 0.02). Our data are consistent with the hypothesis that a higher frequency of p53 mutant cells can be generated under oxidative stress in people with UC. The increased frequency of specific p53 mutated alleles in noncancerous UC colon tissue may confer susceptibility to the development of CRC in an inflammatory microenvironment.

Cancer risk and low-penetrance susceptibility genes in gene-environment interactions

PURPOSE

To provide a concise review for human cancer risk related to low-penetrance genes and their effects on environmental carcinogen exposure.

METHODS

Citation of relevant and recent references for molecular epidemiology, focusing on lung cancer, ethical issues, and some clinical implications of recent molecular epidemiology studies.

RESULTS

Low-penetrance genes contribute to cancer risk by augmenting the effects of carcinogen exposures. These exposures can be measured in the body through molecular dosimetry (ie, the amount of DNA damage), which reflects a biologically effective dose. The examination of tumors and the mutations within tumor suppressor genes, such as p53, can provide etiologic clues for both exposure and susceptibility. Although many studies have focused on carcinogen metabolism and cancer risk, more recent studies are considering DNA repair. Also, we are learning that behavior, such as tobacco addiction, also may be genetically controlled.

CONCLUSION

Sporadic cancers are caused by gene(n)-environment(n) interactions rather than a dominant effect by a specific gene, environmental exposure, or gene-environment interaction. New paradigms, where we categorize genes as caretaker or gatekeeper genes, will allow for new hypotheses to be tested and will require advanced methods of analysis. The goal of molecular epidemiology is to develop risk assessment models for individuals, but currently the most achievable goal will be population risk assessment and a better understanding of carcinogenesis.

Quantitation of benzo[a]pyrene-DNA adducts by postlabeling with 14C-acetic anhydride and accelerator mass spectrometry

Quantitation of carcinogen-DNA adducts provides an estimate of the biologically effective dose of a chemical carcinogen reaching the target tissue. In order to improve exposure-assessment and cancer risk estimates, we are developing an ultrasensitive procedure for the detection of carcinogen-DNA adducts. The method is based upon postlabeling of carcinogen-DNA adducts by acetylation with 14C-acetic anhydride combined with quantitation of 14C by accelerator mass spectrometry (AMS). For this purpose, adducts of benzo[a]pyrene-r-7,t-8-dihydrodiol-t-9,10-epoxide (BPDE) with DNA and deoxyguanosine (dG) were synthesized. The most promutagenic adduct of BPDE, 7R,8S,9R-trihydroxy-10S-(N(2)-deoxyguanosyl)-7,8,9, 10-tetrahydrobenzo[a]pyrene (BPdG), was HPLC purified and structurally characterized. Postlabeling of the BPdG adduct with acetic anhydride yielded a major product with a greater than 60% yield. The postlabeled adduct was identified by liquid chromatography-mass spectrometry as pentakis(acetyl) BPdG (AcBPdG). Postlabeling of the BPdG adduct with 14C-acetic anhydride yielded a major product coeluting with an AcBPdG standard. Quantitation of the 14C-postlabeled adduct by AMS promises to allow detection of attomolar amounts of adducts. The method is now being optimized and validated for use in human samples.

Epidemiology of tobacco carcinogenesis

Tobacco smoking is a worldwide epidemic. Tobacco smoke is an established human carcinogen that contains more than 50 carcinogens, among the most potent of which are polycyclic aromatic hydrocarbons (PAHs) and tobacco- specific nitrosamines (TSNs). Over the last 40 years, the level of tar and nicotine in cigarettes has decreased, along with the level of PAHs, but the level of TSNs has increased. Also, decreases in nicotine content can lead to an attendant increase in smoking in order for an individual to maintain his or her blood nicotine levels. Several factors determine the biologically effective dose of carcinogens, including the number of cigarettes smoked per day, type of cigarette, smoking topography, carcinogen metabolism, and DNA repair. Many studies have shown a relationship between tobacco smoke exposure, carcinogen-DNA adduct formation, tumor specific mutations (eg, p53 mutational spectra), and cancer risk. Genetically determined host capacity can influence these outcomes and the risk for tobacco addiction. Current areas of interest include determining whether women are indeed at greater risk of lung cancer compared with men, and if blacks are at higher risk than women. Also, newer methods can probably clarify the role of environmental tobacco smoke in carcinogenesis.

Interacting effects of the serotonin transporter gene and neuroticism in smoking practices and nicotine dependence

Individual differences in propensity to nicotine dependence appear to be mediated, in part, by genetic factors.1 The serotonin transporter gene has a functional polymorphism (5-HTTLPR) which modulates gene transcription and reuptake.2,3 A possible role in nicotine dependence is suggested by a link between 5-HTTLPR and neuroticism,4 a personality trait which has been related to smoking practices.5 In a cross-sectional study of 185 smokers, we utilized multiple linear regression modeling to examine the interacting effects of the 5-HTTLPR and neuroticism on smoking practices and nicotine dependence. Genotype was classified according to the presence or absence of the short (s) allele vs the long (l) allele of 5-HTTLPR (ie, s/s or s/l vs l/l). Models controlled for gender, age, race, and alcohol use. The 5-HTTLPR by neuroticism interaction effect was statistically significant in the models of nicotine intake (P = 0.05), nicotine dependence (P = 0.001), and smoking motivations (smoking to reduce negative mood (P = 0.01); smoking for stimulation (P = 0.01)). The results suggested that neuroticism was positively associated with these smoking practices among smokers with 5-HTTLPR S genotypes (s/s or s/l), but not among smokers with the L genotype (l/l). The 5-HTTLPR may modify the effects of neuroticism on smoking motivations and nicotine dependence. Assessment of 5-HTTLPR genotype and neuroticism may help to identify smokers who are more responsive to psychotropic medications, such as selective serotonin reuptake inhibitors (SSRIs), which are being used in smoking cessation treatment.

Elevated frequency and functional activity of a specific germ-line p53 intron mutation in familial breast cancer

Previous studies have determined that the frequency of germ-line p53 mutations in familial breast cancer patients is 1% or less, but these reports have not investigated the importance of polymorphic intron base changes in the p53 gene. Therefore, we investigated the frequency of both exon and intron germ-line p53 base changes in 42 breast cancer patients with a strong family history of breast cancer. The mean age of presentation of these patients was 44.0 years (range, 29-69), and 12 of 42 (29%) were of known Ashkenazi ancestry. Purified DNA obtained from the 42 index cases was screened for germ-line p53 mutations in exons 2-11 and surrounding introns using a combination of intron based primers for PCR-single strand conformation polymorphism analysis, direct sequencing, and microarray sequencing using the Affymetrix p53 gene chip methodology. Morphological analysis of apoptosis and cell survival determination were performed on EBV-immortalized lymphoblastoid cell lines from two patients with the p53 intron 6 mutation. A germ-line mutation in the p53 gene at nucleotide 13964 with a G to C base change (13964GC) was identified in 3 of 42 (7.1%) hereditary breast cancer patients. Two patients were heterozygous for this mutation, and one patient had a homozygous mutation. In comparison, 0 of 171 (0%) of sporadic breast cancer patients had the p53 13964GC mutation (P = 0.0003). We found that 0 of 42 (0%) of these hereditary breast cancer patients had other germ-line p53 mutation in exons 2-11. However, pedigree analysis demonstrated that all three patients had strong family histories of multiple types of cancers consistent with Li-Fraumeni syndrome but with late age of onset. Comprehensive BRCA1 and BRCA2 nucleotide analysis from patients with the p53 13964GC mutation revealed no concomitant deleterious BRCA1 or BRCA2 mutations, although they were found in the other hereditary breast cancer patients. Functional analysis of two immortalized lymphoblastoid cell lines derived from patients with the p53 13964GC mutation demonstrated prolonged in vitro survival in response to cisplatinum treatment and showed decreased chemotherapy-induced apoptosis. Immunohistochemical analysis of breast tumors from these patients revealed high levels of mutant p53 protein, suggesting a functional mutation in the p53 gene. In summary, we have identified a single p53 intron mutation in familial breast cancer patients that is present at elevated frequency and has functional activity.

Self-collection of oral epithelial cell DNA under instruction from epidemiologic interviewers

Oral epithelial cells provide an easily accessible source of germline DNA. Two methods for collection were compared in a 1992-1995 case-control study of oral cancer in Puerto Rico. One group of subjects (55 controls without oral cancer) collected oral rinse samples at home or work under the direction of a nonmedically trained interviewer ("self-collection"); the other group (94 controls) participated in a clinic-based collection, which also included blood and urine samples, conducted by a medical technician ("clinic collection"). Participation was higher for self-collection (98.2%) than for clinic collection (70.7%) (p < 0.001). DNA yields ranged from 2.0 to 204.5 microg (median, 25.9 microg) and did not differ by collection method, although yields varied by interviewer among self-collected samples (p = 0.02). Success rates for polymerase chain reaction amplification of the ADH3, NAT1, and multiplex CYP1A1/GSTT1/GSTM1 genotyping assays ranged from 76.4% (NAT1) to 98.2% (ADH3) for self-collected samples and were similar to those for clinic-collected samples (87.2-97.9%). Failure to amplify was associated with low DNA content (p = 0.015). Similar results were observed among cases (91 self-collected, 66 clinic collected), except that DNA yields did not vary by interviewer and a larger fraction (10.2%) of samples contained less than 5 microg of DNA, perhaps because of disease-related oral impairment. Self-collection of oral epithelial DNA samples appears satisfactory and efficient for many epidemiologic studies.

Apolipoprotein E genetic polymorphism, serum lipoproteins, and breast cancer risk

Apolipoprotein E (apoE) is a polymorphic gene involved in lipid metabolism with three common variant alleles (epsilon2, epsilon3, and epsilon4). The epsilon4 allele has been associated with elevated levels of cholesterol as well as greater risk of coronary heart disease and Alzheimer's disease. In this case-control study we examined whether apoE genotype affected the association between serum lipids and breast cancer risk. In a subset of a study in western New York, 260 women with incident, primary breast cancer and 332 community controls were interviewed and provided blood samples. Polymerase chain reaction-restriction fragment length polymorphism analyses of the apoE polymorphism were performed. Participants were classified as apoE2 (epsilon2, epsilon2 or epsilon2, epsilon3), apoE3 (epsilon3, epsilon3), or apoE4 (epsilon4, epsilon4 or epsilon4, epsilon3). No unconditional logistic regression was used to compute adjusted odds ratios (ORs) and 95% confidence intervals (CI). Compared with women with the apoE3 genotype, there were no associations with risk for women with the apoE2 (OR=1.0; 95% CI=0. 91-1.64) or apoE4 genotype (OR=0.97; 95% CI=0.63-1.54). Higher serum levels of total cholesterol, HDL cholesterol, and LDL cholesterol were not associated with risk, either in the total sample or among subgroups of women defined by apoE genotype. Women with the highest serum triglyceride levels had an increase in risk (OR=1.63; 95% CI=1. 03-2.59) compared to women with the lowest levels. This effect was not apparent among women with the apoE2 or apoE3 genotype, but much stronger among women with the apoE4 genotype (OR=4.69; 95% CI=1. 49-14.7). These data suggest that the apoE4 genotype may modify the association between serum triglycerides and breast cancer risk.

Molecular epidemiology of lung cancer

Lung cancer occurs through a complex multistage process that results from the combination of carcinogen exposure and genetic susceptibilities. The primary etiology of lung cancer is tobacco smoking, but an understanding of why some smokers develop lung cancer, and others do not, remains unclear. Current studies focus on genetic susceptibilities to lung cancer, and how they modify the effects of tobacco smoke carcinogens. New assays are being developed to study other contributors to cancer risk, such as interindividual differences in DNA repair. There is current evidence to suggest that the risk of lung cancer for women, compared to men, is higher for the same level of smoking. Several biological differences for the types of lung cancer have been observed in women and men. Also, there appear to be differences in lung cancer between Caucasians and African-Americans. Molecular epidemiology tools are uniquely suited to study these biological differences. These studies will improve cancer risk assessments and focus cancer prevention strategies. Other studies also are focusing on tobacco addiction, in order to lead to improved smoking cessation strategies.

Alcohol dehydrogenase 3 genotype modification of the association of alcohol consumption with breast cancer risk

OBJECTIVES

Because alcohol dehydrogenase 3 (ADH3) is rate-limiting in alcohol oxidation and is polymorphic, we examined ADH3 genotype in relation to alcohol intake and breast cancer risk.

METHODS

We conducted a case-control study among Caucasian women aged 40-85 with incident, pathologically confirmed breast cancer and controls, frequency-matched on age and county. Queries included alcohol intake in the past 20 years. Genomic DNA was genotyped for the exon VIII ADH polymorphism by PCR followed by restriction enzyme digestion. Computation of odds ratios (OR) and 95% confidence intervals (CI) was by unconditional logistic regression.

RESULTS

We found increased risk among pre- (OR 2.3, 95%, CI 1.2-4.3) but not postmenopausal women (OR 1.1, 95% CI 0.7-1.7) associated with ADH3(1-1) compared to ADH3(1-2) and ADH3(2-2) genotypes. Risk was increased for premenopausal women with the ADH3(1-1) genotype and alcohol intake above the median (OR 3.6, 95% CI 1.5-8.8) compared to lighter drinkers with the ADH3(2-2) or ADH3(1-2) genotypes. ORs were close to null for premenopausal women in other drinking and genotype groups and for postmenopausal women categorized by genotype and alcohol consumption.

CONCLUSION

Among premenopausal women there may be a group more genetically susceptible to an alcohol consumption effect on breast cancer risk.

Laboratory methods for the determination of genetic polymorphisms in humans

The determination of genetic polymorphisms for susceptibility to human disease has been rapidly increasing since the introduction of the polymerase chain reaction (PCR). In most laboratories the ability exists to conduct studies on more than 10,000 persons, and the prospect of even larger investigations is approaching. Many methods can be used for genotyping individuals but some are more common and less expensive than others. Newer methods will allow for automation. As the number of studies on genetic polymorphisms increases it is to be expected that more pitfalls will be encountered. While larger studies will reduce the importance of misclassification, quality control methods will have to be applied to the processing of large numbers of samples.

Molecular epidemiological study of non-small-cell lung cancer from an environmentally polluted region of Poland

The p53 mutation spectrum can generate hypotheses linking carcinogen exposure to human cancer. Although it is well-documented that tobacco smoking is a major cause of lung cancer, the contribution of air pollution is less well-established. We determined the molecular and immunohistochemical changes (p53 gene mutations, p53 protein accumulation and WAF1 protein expression) and genetic polymorphisms of GSTM1, CYP1A1 and CYP2D6 genes in a case series of non-small-cell lung cancers from Silesia. This region of southern Poland is highly industrialized with considerable environmental pollution. More than 50% of lung cancers (90/164) contained p53 mutations and 75% showed the combined alteration of the p53 gene and protein accumulation. Males occupationally exposed to coal-derived substances showed a relatively high frequency of squamous and large-cell carcinomas, relatively frequent mutations in codon 298 of p53 and a low frequency of p53 immunohistochemically positive tumours. Codon 298 GAG-->TAG mutations have rarely been found in lung cancers in other populations. We found no correlation between WAF1 protein expression and mutations in the p53 gene or p53 protein accumulation. No statistically significant relationship was found between p53 mutations and GSTM1, CYP1A1, CYP2D6 genotypes. Never smokers with lung cancers from Silesia had a higher frequency of G:C-->T:A transversions than previously reported of the p53 mutation spectrum in never smokers (6/15 vs 4/34; P = 0.06 by chi2). These data are a tentative indication that occupational and environmental exposure to polycyclic aromatic hydrocarbons, such as benzo(a)pyrene, in polluted air contributes to the molecular pathogenesis of lung cancer in never smokers.

An evaluation of proposed frameworks for grouping polychlorinated biphenyl (PCB) congener data into meaningful analytic units

BACKGROUND

Polychlorinated biphenyls (PCBs) have been associated with a variety of health outcomes. Enhanced laboratory techniques can provide a relatively large number of individual PCB congeners for investigation. However, to date there are no established frameworks for grouping a large number of PCB congeners into meaningful analytic units.

METHODS

In a case-control study of serum PCB levels on breast cancer risk, measured levels of 56 PCB congener peaks were available for analysis. We considered several approaches for grouping these compounds based on 1) chlorination, 2) factor analysis, 3) enzyme induction, 4) enzyme induction and occurrence, and 5) enzyme induction, occurrence, and other toxicological aspects. The utility of a framework was based on the mechanism of biologic actions within each framework, lack of collinearity among congener groups, and frequency of detection of PCB congener groups in measured serum levels of 192 healthy postmenopausal women.

RESULTS

Most participants had detectable levels for the proposed PCB congeners groups, using degree of chlorination as a grouping framework. In addition, the previously proposed grouping approach based on enzyme induction, occurrence, and other toxicological aspects was an applicable alternative to the crude approach of grouping by degree of chlorination. Grouping these congeners with respect to P450 enzyme induction activity, and the previously proposed framework based on enzyme induction and occurrence, did not fit these data as well, because only a small proportion of participants had detectable levels for the congener groups with the greatest toxicological potential. Statistical grouping did not result in an interpretable and meaningful clustering of these exposures.

CONCLUSIONS

In these data, grouping with respect to degree of chlorination and the previously proposed framework based on enzyme induction, occurrence, and other toxicological aspects were the most useful approaches to reducing a large number of PCB congeners into meaningful analytic units. Factors affecting the utility of the proposed grouping frameworks are discussed.

Manganese superoxide dismutase (MnSOD) genetic polymorphisms, dietary antioxidants, and risk of breast cancer

Oxidative stress, resulting from the imbalance between prooxidant and antioxidant states, damages DNA, proteins, cell membranes, and mitochondria and seems to play a role in human breast carcinogenesis. Dietary sources of antioxidants (chemical) and endogenous antioxidants (enzymatic), including the polymorphic manganese superoxide dismutase (MnSOD), can act to reduce the load of oxidative stress. We hypothesized that the valine-to-alanine substitution that seems to alter transport of the enzyme into the mitochondrion, changing its efficacy in fighting oxidative stress, was associated with breast cancer risk and that a diet rich in sources of antioxidants could ameliorate the effects on risk. Data were collected in a case-control study of diet and breast cancer in western New York from 1986 to 1991. Caucasian women with incident, primary, histologically confirmed breast cancer were frequency-matched on age and county of residence to community controls. Blood specimens were collected and processed from a subset of participants in the study (266 cases and 295 controls). Using a RFLP that distinguishes a valine (V) to alanine (A) change in the -9 position in the signal sequence of the protein for MnSOD, we characterized MnSOD genotypes in relation to breast cancer risk. We also evaluated the effect of the polymorphism on risk among low and high consumers of fruits and vegetables. Premenopausal women who were homozygous for the A allele had a 4-fold increase in breast cancer risk in comparison to those with 1 or 2 V alleles (odds ratio, 4.3; 95% confidence interval, 1.7-10.8). Risk was most pronounced among women below the median consumption of fruits and vegetables and of dietary ascorbic acid and alpha-tocopherol, with little increased risk for those with diets rich in these foods. Relationships were weaker among postmenopausal women, although the MnSOD AA genotype was associated with an almost 2-fold increase in risk (odds ratio, 1.8; confidence interval, 0.9-3.6). No appreciable modification of risk by diet was detected for these older women. These data support the hypothesis that MnSOD and oxidative stress play a significant role in breast cancer risk, particularly in premenopausal women. The finding that risk was greatest among women who consumed lower amounts of dietary antioxidants and was minimal among high consumers indicates that a diet rich in sources of antioxidants may minimize the deleterious effects of the MnSOD polymorphism, thereby supporting public health recommendations for the consumption of diets rich in fruits and vegetables as a preventive measure against cancer.

Glutathione-S-transferase (GSTM1) genetic polymorphisms do not affect human breast cancer risk, regardless of dietary antioxidants

Glutathione-S-transferases catalyze the detoxication of carcinogen metabolites and reactive oxygen species (ROS) produced through a number of mechanisms. Glutathione-S-transferase (GST) M1 is polymorphic, and the null allele results in a lack of enzyme activity. Because there are indications that ROS may be involved in breast carcinogenesis, we sought to determine whether the GSTM1 null allele was associated with increased breast cancer, particularly among women with lower consumption of dietary sources of alpha-tocopherol, carotenoids and ascorbic acid. In a study of diet and cancer in western New York, women with primary, incident, histologically confirmed breast cancer (n = 740) and community controls (n = 810) were interviewed and an extensive food-frequency questionnaire administered. A subset of these women provided a blood specimen. DNA was extracted and genotyping performed for GSTM1. Data were available for 279 cases and 340 controls. The null allele did not increase breast cancer risk, regardless of menopausal status. There were also no differences in associations between the polymorphism and risk among lower and higher consumers of dietary sources of antioxidants or smokers and nonsmokers. These results indicate that GSTM1 genetic polymorphisms are not associated with breast cancer risk, even in an environment low in antioxidant defenses.

The role of interindividual variation in human carcinogenesis

The process of chemical carcinogenesis is a complex multistage process initiated by DNA damage in growth control genes. Carcinogens enter the body from a variety of sources, but most require metabolic activation before they can damage DNA. There are multiple protective processes that include detoxification and conjugation, DNA repair and programmed cell death. Most of these functions exhibit wide interindividual variation in the population and thus are thought to affect cancer risk. The role of gene-environment interactions is being explored, and current data indicate that genetic susceptibilities can modify carcinogen exposures from the diet and tobacco smoking, although much more data exist for the latter. This review addresses the relationships of human carcinogenesis to these interindividual differences of phase I, phase II and DNA repair enzymes.

Polychlorinated biphenyls, cytochrome P4501A1 polymorphism, and postmenopausal breast cancer risk

In experimental systems, polychlorinated biphenyls (PCBs) induce cytochrome P4501A1 (CYP1A1), which is involved in metabolism of steroid hormones and polycyclic aromatic hydrocarbons in humans. A genetic polymorphism coding for a valine to isoleucine substitution in exon 7 has been associated with lung cancer risk in Japanese populations. In a previous study, we found no association between CYP1A1 genotype and breast cancer risk. However, we were interested in determining whether genotype would relate to risk when PCB body burden was taken into account. In a subset of a case-control study in western New York, 154 postmenopausal women with incident, primary, histologically confirmed postmenopausal breast cancer and 192 community controls were interviewed and underwent phlebotomy. Serum levels of 56 PCB peaks were determined by high resolution gas chromatography with electron capture. PCR-RFLP analyses of the CYP1A1 polymorphism were performed. Unconditional logistic regression was used to compute adjusted odds ratios and 95% confidence intervals. Among women with serum PCB levels above the median of the distribution in the control group, there was increased risk of breast cancer associated with the presence of at least one valine allele, compared with women who were homozygous for the isoleucine alleles (odds ratio, 2.93; 95% confidence interval, 1.17-7.36). Among women with low PCB body burden, no association between CYP1A1 genotype and breast cancer risk was observed. Adjustment for serum lipids and body mass index did not affect the magnitude of the observed associations. PCB body burden may modify the effect of the polymorphism on postmenopausal breast cancer risk through increased CYP1A1 enzyme induction or by activation by specific PCB congeners. These results should be considered preliminary, pending replication by other studies.

Evidence suggesting the role of specific genetic factors in cigarette smoking

Twin studies suggest that propensity to smoke and ability to quit smoking are influenced by genetic factors. As a means of investigating the risk of smoking associated with genetic polymorphisms in the dopamine transporter (SLC6A3) and the D2 dopamine receptor (DRD2) genes, a case-control study of 289 smokers and 233 nonsmoking controls and a case series analysis of smokers were conducted. A significant effect for SLC6A3 and a significant gene-gene interaction were found in a logistic regression model, indicating that individuals with SLC6A3-9 genotypes were significantly less likely to be smokers, especially if they also had DRD2-A2 genotypes. Smokers with SLC6A3-9 genotypes were also significantly less likely to have started smoking before 16 years of age and had prior smoking histories indicating a longer period of prior smoking cessation. This study provides preliminary evidence that the SLC6A3 gene may influence smoking initiation and nicotine dependence.

Molecular epidemiology of human cancer risk: gene-environment interactions and p53 mutation spectrum in human lung cancer

The p53 tumour suppressor gene is at the crossroads of a network of cellular pathways including cell cycle checkpoints, DNA repair, chromosomal segregation, and apoptosis. These pathways have evolved to maintain the stability of the genome during cellular stress from DNA damage, hypoxia, and activated oncogenes. The high frequency of p53 mutations in human cancer is a reflection of the importance of p53 involvement in this network of pathways during human carcinogenesis. An electronic database containing p53 mutations from more than 9000 cancers (http:/(/)www.iarc.fr/p53/homepage.html) can be used to generate hypotheses for further clinical, epidemiological, and laboratory investigations. For example, one can hypothesize that (a) p53 mutations vary in their pathobiological significance; (b) cellular content influences the selection of p53 mutations in clonally derived cancers; (c) the location and type of mutation within the p53 gene provide clues to functional domains in the gene product; and (d) the p53 mutation spectrum can be a molecular link between aetiological agents and human cancer. This review will focus on the role of p53 and cancer susceptibility genes in the molecular pathogenesis and epidemiology of human lung cancer.

p53 mutation spectrum in relation to GSTM1, CYP1A1 and CYP2E1 in surgically treated patients with non-small cell lung cancer

p53 mutation status was analysed in relation to DNA polymorphisms of GSTM1, CYP1A1 and CYP2E1 from 105 surgically resected non-small cell lung cancer cases. Demographic factors, smoking, occupation, family history, tumour histology, grade and stage were taken into account. p53 mutations, detected either directly by DNA sequencing (P = 0.04, adjusted for smoking) or indirectly by immunostaining (P = 0.06), were overrepresented among CYP1A1 variants. Mutations in exon 8 and transitions at CpG sites in the p53 gene were favoured in this subset. There was no relation between the individual gene polymorphisms or p53 mutations and disease-free survival by Kaplan-Meier analysis. The finding of excess CYP1A1 heterozygotes in individuals with p53 mutations after adjustment for smoking suggests that CYP1A1 activation contributes to lung cancer via p53 inactivation.

Risk of recurrent spontaneous abortion, cigarette smoking, and genetic polymorphisms in NAT2 and GSTM1

Maternal smoking increases the risk of spontaneous abortion. Polymorphic N-acetyltransferase (NAT2) and glutathione S-transferase (GSTM1) affect metabolism of some mutagens found in tobacco smoke. Genotypes and smoking were studied in women with at least two spontaneous abortions (N = 32) and those with at least two livebirths (N = 179). Smoking slightly increased risk (odds ratio = 1.3; 95% confidence interval = 0.6-2.9), but NAT2 and GSTM1 did not. NAT2 or GSTM1 polymorphisms did not appreciably modify smoking-related risk.

Dopamine D4 receptors and the risk of cigarette smoking in African-Americans and Caucasians

An understanding of why people smoke cigarettes can have an important impact on smoking prevention and cessation. People smoke cigarettes to maintain nicotine levels in the body, and nicotine has been implicated in the stimulation of brain reward mechanisms via central neuronal dopaminergic pathways. In this study, we evaluated the association of smoking and smoking cessation with a dopamine D4 receptor 48-bp variable nucleotide tandem repeat polymorphism in which the seven-repeat allele (D4.7) reduces dopamine affinity. Smokers (n = 283) and nonsmokers (n = 192) were recruited through local media for a case-control study of smoking. After giving informed consent and answering a behavioral questionnaire, smokers underwent a single minimal-contact session of smoking cessation counseling and then were followed for up to 1 year. The frequency of the dopamine D4 receptor genetic polymorphism using PCR was determined, and individuals were classified by the number of repeat alleles (two to five repeats as S and six to eight repeats as L). Persons with those genotypes including only S alleles (homozygote S/S) were compared with those with at least one L allele (heterozygote S/L and homozygote L/L). Chi2 tests of association, Fisher's exact test, and Student's t test were used. Ps were two-tailed. The data show that African-Americans (n = 72) who had at least one L allele had a higher risk of smoking (odds ratio, 7.7; 95% confidence interval, 1.5-39.9; P = 0.006), shorter time to the first cigarette in the morning (P = 0.03), and earlier age at smoking initiation (P = 0.09) compared with homozygote S/S genotypes. After smoking cessation counseling, none of the African-American smokers with an L allele were abstinent at 2 months, compared with 35% of the smokers who were homozygote S/S (P = 0.02). The analysis of Caucasians (n = 403) did not suggest a similar smoking risk for the D4 genotypes (odds ratio, 1.0; 95% confidence interval, 0.6-1.6; P = 0.90), or smoking cessation (P = 0.75). Although the number of African-Americans is small, this study is consistent with the hypothesis that the L alleles increase the risk of smoking because these individuals are prone to use nicotine to stimulate synaptic dopamine transmission. If replicated, the data indicate that a single minimal-contact session of cessation counseling, similar to what is typically provided in primary care physician offices, is ineffective in African-American smokers who have at least one L allele. The finding of an effect for these polymorphic loci in African-Americans, but not Caucasians, suggests that the variable nucleotide tandem repeat studied here is a marker for another polymorphic site in African-Americans, but not in Caucasians.

Genetic polymorphisms in catechol-O-methyltransferase, menopausal status, and breast cancer risk

Polymorphic catechol-O-methyltransferase (COMT) catalyzes the O-methylation of estrogen catechols. In a case-control study, we evaluated the association of the low-activity allele (COMT(Met)) with breast cancer risk. Compared to women with COMT(Val/Val), COMT(Met/Met) was associated with an increased risk among premenopausal women [odds ratio (OR), 2.1; confidence interval (CI), 1.4-4.3] but was inversely associated with postmenopausal risk (OR, 0.4; CI, 0.2-0.7). The association of risk with at least one low-activity COMT(Met) allele was strongest among the heaviest premenopausal women (OR, 5.7; CI, 1.1-30.1) and among the leanest postmenopausal women (OR, 0.3; CI, 0.1-0.7), suggesting that COMT, mediated by body mass index, may be playing differential roles in human breast carcinogenesis, dependent upon menopausal status.

Characterisation of xenobiotic-metabolising enzyme expression in human bronchial mucosa and peripheral lung tissues

The human respiratory epithelium is in direct contact with chemical carcinogens and toxins in inhaled air. Therefore, the activities of xenobiotic-metabolising enzymes in this epithelium could modulate respiratory toxicity and carcinogenesis. We determined the expression of several xenobiotic-metabolising enzymes, including phase I and phase II enzymes, in human bronchial mucosa and peripheral lung tissues. Reverse transcription-polymerase chain reaction (RT-PCR) analysis of phase I enzymes showed CYP1A1 and CYP2C (CYP2C8 and CYP2C18) mRNA expression in all of the 14 bronchial mucosa specimens. CYP2A6 and CYP2B6 mRNAs were found in 85% of the samples, whereas 50 and 90% of the tissues displayed CYP2E1 and CYP3A5 expression, respectively. However, CYP1A2, CYP2D6 and CYP3A4 mRNAs were not detected in all samples analysed. Normal human bronchial epithelial cells (NHBE cells) cultured in serum-free conditions showed reduced P450 expression in comparison with the bronchial mucosal samples. Similar to the bronchial mucosa, the peripheral lung tissues expressed CYP1A1, CYP2A6, CYP2B6, CYP2C (CYP2C8 and CYP2C18), CYP2E1 and CYP3A5 mRNAs, but did not show detectable levels of CYP2D6. Additional P450s, such as CYP1A2 and CYP3A4, were detected. The expression of CYP1A1, CYP1A2, CYP2B6, CYP2E1 and CYP3A4/5 in peripheral lung tissues was confirmed at the protein level, whereas CYP2A6 protein was undetectable. The use of specific primers for the detection of the phase II isoenzymes belonging to the glutathione S-transferase mu (GST mu) and N-acetyl transferase (NAT) families showed that GSTM1 was expressed in 40% of the bronchial mucosa and 25% of the peripheral lung tissues, whereas GSTM3 and NAT1 mRNAs were found in all bronchial and lung samples. Finally, NAT2 expression was detected in all peripheral lung tissues, but was not detected in the bronchus. In conclusion, these results describing the diversity of the xenobiotic-metabolising enzymes expressed in the bronchus and lung tissues indicate that the human respiratory system could significantly and specifically contribute to the activation and metabolism of several environmental procarcinogens.

Depression and self-medication with nicotine: the modifying influence of the dopamine D4 receptor gene

This study evaluated whether there are genetic subgroups of depressed individuals who are more or less predisposed to engage in self-medication smoking practices. Smokers (N = 231) completed self-report questionnaires of depression and smoking practices and were genotyped for the dopamine D4 receptor (DRD4) gene. A significant interaction (DRD4 Genotype x Depression) was found for stimulation smoking and negative-affect reduction smoking. Specifically, these smoking practices were significantly heightened in depressed smokers homozygous for the short alleles of DRD4 but not in those heterozygous or homozygous for the long alleles of DRD4. These preliminary results suggest that the rewarding effects of smoking and the beneficial effects of nicotine replacement therapy for depressed smokers may depend, in part, on genetic factors involved in dopamine transmission.

Breast cancer risk, meat consumption and N-acetyltransferase (NAT2) genetic polymorphisms

Although inconsistencies exist, some studies have shown that meat consumption is associated with breast cancer risk. Several heterocyclic amines (HAs), formed in the cooking of meats, are mammary carcinogens in laboratory models. HAs are activated by polymorphic N-acetyltransferase (NAT2) and rapid NAT2 activity may increase risk associated with HAs. We investigated whether ingestion of meat, chicken and fish, as well as particular concentrated sources of HAs, was associated with breast cancer risk, and if NAT2 genotype modified risk. Caucasian women with incident breast cancer (n = 740) and community controls (n = 810) were interviewed and administered a food frequency questionnaire. A subset of these women (n = 793) provided a blood sample. Polymerase chain reaction and restriction fragment length polymorphism analyses were used to determine NAT2 genotype. Consumption of red meats, as well as an index of concentrated sources of HAs, was not associated with increased breast cancer risk, nor did risk vary by NAT2 genotype. In post-menopausal women, higher fish consumption was inversely associated with risk (odds ratio = 0.7; 95% confidence interval, 0.4-1.0); among pre-menopausal women, there was the suggestion of inverse associations between risk and pork and chicken intake. Our results suggest that consumption of meats and other concentrated sources of HAs is not associated with increased breast cancer risk. However, due to the strong biologic plausibility for a role of some HAs in mammary carcinogenesis, and the likely measurement error in evaluation of sources of HAs in this study, further studies of these possible relationships are warranted.

Environmental organochlorine exposure and postmenopausal breast cancer risk

Environmental exposure to organochlorine compounds has been associated with a potential role in breast cancer etiology, but results from previous investigations yielded inconsistent results. In this case-control study, we examined the effect of 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE), hexachlorobenzene (HCB), mirex, and several measures of polychlorinated biphenyls (PCBs) on postmenopausal breast cancer risk. The study sample included 154 primary, incident, histologically confirmed, postmenopausal breast cancer cases and 192 postmenopausal community controls. Usual diet, reproductive and medical histories, and other lifestyle information was obtained by an extensive in person interview. Serum levels (ng/g) of DDE, HCB, mirex, and 73 PCB congeners were determined by gas chromatography with electron capture. PCB exposure was examined as total measured PCB levels, total number of detected PCB peaks, and three PCB congener groups. In the total sample, there was no evidence of an adverse effect of serum levels of DDE [odds ratio (OR), 1.34; 95% confidence interval (CI) 0.71-2.55], HCB (OR, 0.81; 95% CI, 0.43-1.53), or mirex (OR, 1.37; 95% CI, 0.78-2.39). Further, higher serum levels of total PCBs (OR, 1.14; 95% CI, 0.61-2.15), moderately chlorinated PCBs (OR, 1.37; 95% CI, 0.73-2.59), more highly chlorinated PCBs (OR, 1.19; 95% CI, 0.60-2.36), or greater number of detected peaks (OR, 1.34; 95% CI, 0.72-2.47) were not associated with increased risk. There was some indication of a modest increase in risk for women with detectable levels of less chlorinated PCBs (OR, 1.66; 95% CI, 1.07-2.88). Among parous women who had never lactated, there was some evidence for increased risk, associated with having detectable levels of mirex (OR, 2.42; 95% CI, 0.98-4.32), higher serum concentrations of total PCBs (OR, 2.87; 95% CI, 1.01-7.29), moderately chlorinated PCBs (OR, 3.57; 95% CI, 1.10-8.60), and greater numbers of detected PCB congeners (OR, 3.31; 95% CI, 1.04-11.3). These results suggest that an increase in risk of postmenopausal breast cancer associated with environmental exposure to PCBs and mirex, if at all present, is restricted to parous women who had never breast-fed an infant. Future studies should consider lactation history of participants, as well as use similar epidemiological and laboratory methodologies, to ensure comparability of results across studies.

The role of the serotonin transporter gene in cigarette smoking

Data from twin studies have suggested that cigarette smoking has a significant heritable component. The serotonin transporter gene (5-HTT) is a plausible candidate gene for smoking predisposition because of its association with psychological traits relevant to smoking behavior. The present investigation evaluated the associations of smoking practices and smoking cessation with a common polymorphism in the upstream regulatory region of 5-HTT that is manifested as either an inserted (long) variant or a deleted (short) variant. The short variant of the polymorphism is associated with reduced transcription of the gene promoter and diminished uptake. A case-control study design (268 smokers and 230 controls) was used to evaluate the associations of 5-HTT genotype with smoking status. Case series analysis of smokers was used to evaluate the role of 5-HTT in age at smoking initiation, previous quitting history, current smoking rate, and 12-month quit rate following a minimal-contact smoking cessation program. There were no significant differences in the distribution of 5-HTT genotypes in smokers as compared with nonsmokers in either Caucasians or African Americans, nor was the 5-HTT genotype associated with the smoking outcome variables. However, the results did reveal significant racial differences in the distribution of 5-HTT genotypes: Caucasians were significantly more likely to carry the short variant of the 5-HTT gene than were African Americans (P = 0.005). These findings suggest that the 5-HTT gene may not play a significant role in cigarette smoking practices.

Apolipoprotein E allelic frequency in elderly smokers

Susceptibility genes for human diseases (e.g., cancer and atherosclerosis) increase disease risk by altering the metabolic activation of exogenous (e.g., carcinogens) and endogenous (e.g., cholesterol) compounds. The function of these genes, and subsequent risk, can be adversely affected by polymorphisms. This study tests the hypothesis that if specific genetic polymorphisms are related to mortality, then in elderly heavy smokers, there should be a decreased frequency of "at risk" alleles and an increased frequency of "protective" alleles, i.e., a survival effect. One such potential polymorphism is in the apolipoprotein E (apoE) gene, which is involved in cholesterol metabolism, where the epsilon4 allele is associated with an increased risk of coronary artery disease and is under represented in elderly populations. In this study, ApoE variant alleles were determined in 81 living, elderly current smokers (mean age: 72.5; range: 65-94; mean pack-years: 78; range: 13-192) and in 82 younger autopsy donors (mean age: 33; range: 1-58). There was a borderline difference in the apoE 4 allelic frequencies among the groups (11% in the elderly and 18% in the comparable younger group [df = 1; chi(2) = 4.02; P = 0.05]). A significant difference was found for age when stratified as a continuous variable by genotype in the elderly smokers (P = 0.03; mean age for persons with and without epsilon4 was 69.9 and 73.2, respectively). Pack-years of cigarette smokers did not differ by genotype, indicating no selective effect. These results confirm earlier associations for differences in the apoE allelic frequencies in the elderly and extend it to smokers, who generally have increased mortality at younger ages.