Genetic polymorphisms and lung cancer susceptibility: a review

Impacts of heavy smoking on non-coding RNA expression for patients with esophageal carcinoma

BACKGROUND

Smoking is a well-recognized risk factor for esophageal carcinoma, but the underlying molecular mechanism remains unclear. Previous studies have demonstrated the predictive value of non-coding RNA (ncRNA) for the prognosis of esophageal carcinoma; however, the expression of smoking-related ncRNAs has not been systematically characterized. Herein, we comprehensively assessed the hazard of heavy smoking and its impact on ncRNA expression patterns in patients with esophageal carcinoma.

METHODS

Transcriptome and clinical features of patients with esophageal carcinoma were acquired from The Cancer Genome Atlas (TCGA) database. Cox regression analysis was employed to calculate the hazard ratio (HR) of smoking behavior. Differential expression analysis was conducted with the "edgeR" package. The smoking-related RNA regulatory network was based on lncRNA‒miRNA and miRNA‒mRNA pairs and visualized by Cytoscape 3.7.1. We applied Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses for functional annotation. Univariate and least absolute shrinkage and selection operator (LASSO) Cox regression analyses were used for model construction. We applied Kaplan‒Meier analysis with a log-rank test for survival analysis, with group comparison by the Wilcoxon signed ranked test.

RESULTS

Heavy smoking contributed to the poor overall survival of esophageal carcinoma, with an HR of 3.167 (95% CI: 1.077-9.312). A total of 195 lncRNAs and 73 miRNAs were differentially expressed between patients with or without smoking behavior. We constructed smoking-related RNA regulatory networks, and functional annotation enriched a series of cancer-related pathways. We generated a smoking-related prognostic risk score and found that patients with a high score had a poor prognosis. Fourteen out of 23 immune cell types differentially infiltrated into a distinct risk group, while no correlation was observed between the risk score and immune cells.

CONCLUSION

Altogether, we profiled smoking-related ncRNA expression patterns and constructed an RNA regulatory network, providing a landscape of smoking-related molecular mechanisms of esophageal carcinoma. The smoking-related risk score, which was related to prognosis, revealed that tobacco smoking could suppress tumor immunity via the ncRNA mechanism.

Analysis of MMP-2-735C/T (rs2285053) and MMP-9-1562C/T (rs3918242) Polymorphisms in the Risk Assessment of Developing Lung Cancer

Matrix metalloproteinase (MMP)-2 and -9 are gelatinases which are capable of degrading type IV collagen and have been linked to cancer invasion and metastatic development. MMP-2 and MMP-9 gene polymorphisms may affect their biological function, and thus their role in cancer development and progression. We analyzed the association of the polymorphism frequencies of MMP-2-735C/T and MMP-9-1562C/T with MMP-2 and MMP-9 serum concentrations, as well as their potential effects in lung cancer patients. We conducted a retrospective, case-control study consisting of 112 lung cancer patients and 100 healthy individuals from a Caucasian population in Poland. Polymerase chain reaction with restriction fragment length polymorphism (PCR/RFLP) and electrophoresis was used to genotype genomic DNA from whole blood samples. MMP-2 and MMP-9 serum concentrations were then determined using ELISA. For statistical analysis, Statistica version 13 from TIBCO Software Inc. was utilized with a significance level <0.05. Logistic regression analysis revealed that MMP-2-735CC (OR = 5.39; 95% CI = 0.62-47.17; p = 0.238504) and -735CT genotype (OR = 7.22; 95% CI = 0.78-67.14; p = 0.072836), as well as MMP-9-1562CC (OR = 1.45; 95% CI = 0.31-6.70; p = 0.757914) and -1562CT genotype (OR = 1.60; 95% CI = 0.33-7.83; p = 0.548801) were associated with a higher risk of lung cancer. There were statistically significant differences observed in the MMP-2 concentration between individuals with the -735CC genotype and the -735CT genotype (non-smoking control: 204.04 ng/mL vs. 237.00 ng/mL, respectively, p = 0.041479; adenocarcinoma patients: 157.69 ng/mL vs. 126.37 ng/mL, respectively, p = 0.013222), as well as differences in the MMP-9 concentration between individuals with the -1562CC genotype and the -1562CT genotype (smoking control: 385.67 ng/mL vs. 562.80 ng/mL, respectively, p = 0.000936; patients with other lung neoplasms: 821.64 ng/mL vs. 928.88 ng/mL, respectively p = 0.023315). The role of MMP-2-735C/T and MMP-9 -1562C/T polymorphisms in an increased risk of lung cancer cannot be dismissed. Specific genotypes affect MMP-2 and MMP-9 concentrations in both lung cancer patients and healthy controls, which may thereby increase lung cancer risk, disease aggressiveness, and patient survival outcomes.

Prediction of Lung Nodule Progression with an Uncertainty-Aware Hierarchical Probabilistic Network

Predicting whether a lung nodule will grow, remain stable or regress over time, especially early in its follow-up, would help doctors prescribe personalized treatments and better surgical planning. However, the multifactorial nature of lung tumour progression hampers the identification of growth patterns. In this work, we propose a deep hierarchical generative and probabilistic network that, given an initial image of the nodule, predicts whether it will grow, quantifies its future size and provides its expected semantic appearance at a future time. Unlike previous solutions, our approach also estimates the uncertainty in the predictions from the intrinsic noise in medical images and the inter-observer variability in the annotations. The evaluation of this method on an independent test set reported a future tumour growth size mean absolute error of 1.74 mm, a nodule segmentation Dice’s coefficient of 78% and a tumour growth accuracy of 84% on predictions made up to 24 months ahead. Due to the lack of similar methods for providing future lung tumour growth predictions, along with their associated uncertainty, we adapted equivalent deterministic and alternative generative networks (i.e., probabilistic U-Net, Bayesian test dropout and Pix2Pix). Our method outperformed all these methods, corroborating the adequacy of our approach.

Population attributable fraction of lung cancer due to genetic variants, modifiable risk factors, and their interactions: a nationwide prospective cohort study

BACKGROUND

Genetic variants and modifiable risk factors (including environmental exposure and lifestyle) greatly contribute to the development of lung cancer. The population attributable fraction (PAF) of these risk factors, especially their interactive effects, has not been well quantified.

METHODS

A total of 398,577 participants were included in this analysis. There were 2504 incident lung cancer cases identified over an average 10.4-year follow-up. We applied Cox proportional hazards models to examine the associations between risk factors and incident lung cancer. We further developed a polygenic risk score and evaluated whether environmental factors modified the effect of genetic risk on incident lung cancer. Furthermore, we calculated the PAF for each risk factor, as well as their gene-environment additive interaction, and then combined them to create a weighted PAF that takes into consideration participants with overlapping risk factors.

RESULTS

Our analysis showed that smoking was the leading risk factor for lung cancer with a PAF of 63.73%. We observed additive interactions between smoking, PM_2.5, NO_x, and genetic risk, with PAFs of 17.85% (smoking-high genetic risk interaction), 10.79% (smoking-intermediate genetic risk interaction), 5.30% (NO_x-high genetic risk interaction), 6.55% (PM_2.5-high genetic risk interaction), and 4.99% (PM_2.5-intermediate genetic risk interaction). We estimated that 73.46% of lung cancer cases could be attributable to potentially modifiable risk factors after adjusting for the correlation between them.

CONCLUSION

High genetic risk and several modifiable factors may increase the risk of incident lung cancer. Participants with a high genetic risk may be more vulnerable to developing lung cancer if exposed to smoking and/or high air pollution. Our findings provide evidence that the majority of incident lung cancer cases could be prevented by eliminating modifiable risk factors.

Analysis of whole-exome data of cfDNA and the tumor tissue of non-small cell lung cancer

Background

Non-small cell lung cancer (NSCLC) has the highest cancer mortality rate in the world, but currently there is no effective method of dynamic monitoring. Gene mutation is an important factor in tumorigenesis and can be detected using high-throughput sequencing technology. This study aimed to analyze the driving genes in the tumor of NSCLC patients by whole exon sequencing, and to compare and analyze the subclones of the tumor at different time points.

Methods

We collected 87 cases of NSCLC tumor tissues, para-cancer tissues, and peripheral blood samples for detecting cell-free DNAs (cfDNAs) from January 2016 to December 2018, and whole-exome sequencing was performed. The gene mutation map of NSCLC was drawn in detail by second-generation sequencing data analysis and new driver genes were found. In addition, we performed a subclonal analysis of tumors from different stages of the same patient to further describe the tumor heterogeneity.

Results

We found that the clonal analysis obtained by cfDNA detection was similar to the clonal analysis of the tissue samples, so real-time monitoring of tumor changes can be carried out through monitoring cfDNA.

Conclusions

This study provides evidence for studying the gene mutation information of NSCLC and shows the importance of cfDNA in the analysis of tumor subcloning information.

Genetic polymorphism of lysyl oxidase, glutathione S-transferase M1, glutathione-S-transferase T1, and glutathione S-transferase P1 genes as risk factors for lung cancer in Egyptian patients

Lung cancer is a lethal malignancy and is affected by genetic polymorphisms that contribute to an individual's susceptibility to developing the disease. Several studies on lung cancer showed conflicting results. The aim of this study is to investigate whether individual or combined modifying effects of LOX G/A, GSTM1 active/null, GSTT1 active/null and GSTP1 Ile/Val polymorphisms are related to the risk of lung cancer in relation to smoking in the Egyptian population. This study is a hospital-based case control study that included 200 patients and 200 control subjects. Genotyping of the 4 studied genes was determined by Multiplex PCR for GSTM1 and GSTT1 and Taq man SNP assay for GSTP1 and LOX genes. The LOX G/A and GSTP1 Ile/Val in both homozygous and heterozygous variants, and the GSTM1 and GSTT1 null genotype showed significant association with lung cancer. Combination between gene polymorphism and smoking increased the risk of developing cancer by 2.7 fold in the LOX GA+AA variant, 1.9 fold in the GSTM1 null variant, 4.8 fold in the GSTT1 null variant and 4.3 fold in the GSTP1 Ile/Val+Val/Val variant. The genetic combination (LOX GA+AA/GSTT1 active, LOX GG/GSTT1 null, LOX GA+AA/GSTT1 null, LOX GA+AA/GSTP1 Ile/Ile, LOX GG/GSTP1 Ile/Val+Val/Val and LOX GA+AA/GSTP1 Ile/Val+Val/Val) led to a higher lung cancer risk, compared to the reference group. The LOX GA/AA, GSTM1 null, GSTT1 null and GSTP1 Ile/Val, Val/Val genotypes contributed to increased lung cancer susceptibility. To the best of our knowledge, this is the first study of LOX genotyping in the Egyptian population. The combination of genotypes increased the risk of cancer, indicating the importance of gene-gene interaction and giving a targeted preventive approach.

Establishment of multiplex allele-specific blocker PCR for enrichment and detection of 4 common EGFR mutations in non-small cell lung cancer

Background

Lung cancer is one of the most severe cancers and the majority of patients miss the best timing for surgery when diagnosed, thus having to rely on radiotherapy, chemotherapy or target therapy. Epidermal growth factor receptor (EGFR) upregulation occurs in a large percentage of patients, who can then benefit from tyrosine kinase inhibitors (TKI). However, the EGFR mutations they carry will vary the effectiveness of TKI. Circulating tumor DNA (ctDNA) contains genetic information from cancer tissue that can be used as a liquid biopsy by non-invasive sampling. This study aimed to provide a solution for minor allele detection from ctDNA.

Methods

Our novel method, named multiplex allele-specific blocker PCR (MAB PCR), combines amplification refractory mutation system (ARMS), blocker PCR and fluorescent-labeled probes for better discrimination and higher throughput. MAB PCR was specially designed for low-quality samples such as ctDNA. A sensitive assay based on MAB PCR was developed for enriching and detecting four common EGFR mutations. This assay was optimized and evaluated with manufactured plasmids, and validated with 34 tissue samples and 94 plasma samples.

Results

The limit of detection of this assay was 10² copies and the detection sensitivity reached 0.1% mutant allele fraction (MAF). The results of clinical sample testing had 100% accordance with sequencing, which proved that this assay was accurate and applicable in clinical settings.

Conclusions

This assay could accomplish low-cost and rapid detection of 4 common EGFR mutations sensitively and accurately, which has huge potential in clinical usage for guiding medication. Furthermore, this design could be used to detect other mutations.

The influence of DNMT3A and DNMT3B gene polymorphisms on acute myeloid leukemia risk in a Moroccan population

Acute myeloid leukemia (AML) is a very complex disease that is linked to environmental, genetic and epigenetic factors. Several Studies have found that aberrations in DNA methylation process play a crucial role in leukemogenesis. The aim of this case control study was to evaluate the association between rs1569686, rs2424913 polymorphisms located in DNMT3B gene and rs7590760 polymorphism located in DNMT3A gene and AML risk in a Moroccan population.

MATERIALS AND METHODS

The present study was conducted in 142 cases of AML and 179 control subjects from the Moroccan population. Genomic DNA was isolated from whole blood samples by salting-out method and the genotype of the three polymorphisms was determined by the PCR-RFLP technique.

RESULTS

The study results indicated that rs1569686 polymorphism was significantly associated with the risk of AML in dominant model (OR=1.72, 95 % CI 1.01-2.95, P=0.04), but not in recessive model. In stratified analysis by gender, statistically significant association between the rs2424913 CT genotype and AML was found among males (OR=2.05, 95 % CI 1.00-4.19, P=0.04). Similarly, the rs1569686 TT genotype was associated with an increase risk of AML (OR=3.21, 95 % CI 1.15-8. 98, P=0.02), this association was also found under dominant genetic model (OR=2.47, 95 % CI 1.07-5. 67, P=0.03) among males. However, the rs2424913 polymorphism was not associated with AML.

CONCLUSION

Our findings have shown that rs1569686 polymorphism might be a risk factor of AML in males. While, the rs2424913 polymorphism was not associated with AML. Further studies with a large sample size are needed to validate our results.

The association Between Occupational Exposure to silica and Risk of Developing Rheumatoid Arthritis: A Meta-Analysis

Background

Rheumatoid arthritis (RA) is an autoimmune disease with systemic inflammatory arthritis. This meta-analysis was conducted to examine the association between occupational exposure to silica and the risk of developing RA among different workers.

Methods

In this meta-analysis, we searched relevant published studies using major electronic databases including Scopus, PubMed, ISI Web of Science, and Google Scholar search engine up to October 2019, and the references of retrieved articles were also checked for further possible sources. A random-effects model was used to account for heterogeneity among the results of the studies using the pooled odds ratios (ORs) and their 95% confidence intervals (CIs). The Q-statistic and I² tests were calculated to assess heterogeneity between the studies.

Results

The pooled calculation of OR indicated a significant association between occupational exposure to silica and risk of developing RA among different workers (OR = 2.59, 95% CI = 1.73 to 3.45). In addition, the pooled estimates of OR in smokers were statistically significant (OR = 2.49, 95% CI = 1.13 to 3.86).

Conclusions

The findings of the present study reveal that occupational exposure to silica may be associated with increased risk of developing RA.

Burden of disease at the same limit of exposure to airborne polycyclic aromatic hydrocarbons varies significantly across countries depending on the gap in longevity

Atmospheric polycyclic aromatic hydrocarbons (PAHs) disproportionately affect human health across the globe, and differential exposure is believed to drive the unequal health burden. Therefore, this study assessed and compared the burden of disease, in disability-adjusted life years (DALYs), at the same level (or limit) of exposure to atmospheric PAHs in nine countries. We calculated the DALYs per person-year per ng/m³ of benzo[a]pyrene from ten cancers and thirty-four non-cancer adverse outcomes using published toxicity information and country-specific disease severity. Exposure duration was averaged over 30 years and we adjusted for early-life vulnerability to cancer. The DALYs per person-year per ng/m³ of fifteen other individual PAHs was calculated using relative potency factors, and toxicity factors derived from quantitative structure-activity relationships. We found that even at the same level of exposure to PAHs, the incremental burdens of disease varied substantially across countries. For instance, they varied by about 2-3 folds between Nigeria and the USA. Countries having the lowest longevity had the highest DALYs per person-year per ng/m³ of each PAH. Kruskal-Wallis test (α = 0.05) showed that the variation across countries was significant. The post hoc tests detected a significant difference between two countries when the gap in longevity was >10 years. This suggests that countries having very low average life expectancy require more stringent PAH limit. Linear or exponential function of average longevity gave valid approximation of the DALYs per person-year per ng/m³ of benzo[a]pyrene or phenanthrene, respectively. Furthermore, we used global gridded surface benzo[a]pyrene concentrations and global population dataset for 2007, with spatial resolution of 0.1° × 0.1°, to calculate the contribution of differential exposures to the estimated DALYs per person-year. We found that in six out of nine countries, differential exposures to PAH contribute less to the estimated health loss than differential severities of the diseases. This indicates that the risk to health from PAHs may be underreported if the severities of the diseases in the countries are not considered.

Polymorphisms in cancer-related pathway genes and lung cancer

We evaluated the associations between potentially functional variants in a comprehensive list of cancer-related genes and lung cancer in a Korean population.

A total of 1969 potentially functional single nucleotide polymorphisms (SNPs) of 1151 genes involved in carcinogenesis were evaluated using an Affymetrix custom-made GeneChip in 610 nonsmall cell lung cancer patients and 610 healthy controls. A replication study was conducted in an independent set of 490 cases and 486 controls. 68 SNPs were significantly associated with lung cancer in the discovery set and tested for replication.

Among the 68 SNPs, three SNPs (corepressor interacting with RBPJ 1 (CIR1) rs13009079T>C, ribonucleotide reductase M1 (RRM1) rs1465952T>C and solute carrier family 38, member 4 (SLC38A4) rs2429467C>T) consistantly showed significant associations with lung cancer in the replication study. In combined analysis, adjusted odds ratio for CIR1 rs13009079T>C, RRM1 rs1465952T>C and SLC38A4 rs2429467C>T were 0.69, 0.71 and 0.73, respectively (p=4×10−5, 0.01 and 0.001, respectively) under the dominant model. The relative mRNA expression level of CIR1 was significantly associated with rs13009079T>C genotypes in normal lung tissues (ptrend=0.03).

These results suggest that the three SNPs, particularly CIR1 rs13009079T>C, may play a role in the pathogenesis of lung cancer.

Detection of HER2 polymorphism and expression using circulating DNA and RNA as a tool in lung adenocarcinoma patients: a case control study

BACKGROUND

Circulating DNA and RNA is an important prognostic tool for noninvasive malignant disease detection and in disease prognosis. Study aimed to evaluate the possible prognostic role of HER2 (-3444C/T) promoter polymorphism and its mRNA expression in Lung adenocarcinoma patients using circulating DNA and RNA.

METHODS

One hundred newly diagnosed lung adenocarcinoma patients and 100 age and sex matched healthy controls were included and allele specific (AS) polymerase chain reaction (PCR) was used for genotyping and expression was analyzed by quantitative real time PCR. Overall survival of patients was analyzed by Kaplan-Meier method.

RESULTS

We observed a statistically significant difference in the frequency of HER2 CC, CT, and CT genotype among lung adenocarcinoma cases vs. healthy controls (P=0.001). Compared to the CC genotype, OR 2.51 (1.4-4.51), 5.97 (1.17-30.41) and RR 1.56 (1.17-2.07), 2.83 (0.82-9.73) for heterozygous CT and homozygous TT genotypes suggesting possible dominant effect on risk of lung adenocarcinoma. Cases with CC genotype showed 9.29 fold increased mRNA expression while cases with heterozygous CT and homozygous TT genotype showed 16.26, 16.72 fold increased mRNA expression (P<0.0001). We observed 13.92 fold increased HER2mRNA expression Lung adenocarcinoma patients. Patients in different TNM stages showed significant difference in HER2 mRNA expression which was found to be significantly associated (P<0.0001). Patients with distant metastases and without distant metastases had 17.44 and 11.16 fold increased HER2 mRNA expression was also found to be significantly associated (P<0.0001). It was also observed that patients with pleural effusion and without pleural effusion showed significant difference in HER2 mRNA expression (P=0.03). We also analysed patients with CC, TT, CT (P=0.02) and CT + TT (P=0.008) genotype showed 15.8, 7.9, 9.5 and 7.9 months of overall median survival time and found to be significantly associated, respectively. Patients with >13 and ≤13 fold increased HER mRNA expression also showed 7.9 and 11.5 months of overall median survival time was also found to be significantly associated (P=0.01).

CONCLUSIONS

Our work provides evidence that circulating DNA and RNA may be a potential prognostic tool in Lung adenocarcinoma patients. Promoter polymorphism of HER2 (-3444C/T) gene had significant impact on higher HER2 mRNA expression could be a predictive factor for patients' worse overall survival and metastatic behaviour.

Heavy chain single-domain antibodies to detect native human soluble epoxide hydrolase

The soluble epoxide hydrolase (sEH) is a potential pharmacological target for treating hypertension, vascular inflammation, pain, cancer, and other diseases. However, there is not a simple, inexpensive, and reliable method to estimate levels of active sEH in tissues. Toward developing such an assay, a polyclonal variable domain of heavy chain antibody (VHH) sandwich immunoassay was developed. Ten VHHs, which are highly selective for native human sEH, were isolated from a phage-displayed library. The ten VHHs have no significant cross-reactivity with human microsomal epoxide hydrolase, rat and mouse sEH, and denatured human sEH. There is a high correlation between protein levels of the sEH determined by the enzyme-linked immunosorbent assay (ELISA) and the catalytic activity of the enzyme in S9 fractions of human tissues (liver, kidney, and lung). The VHH-based ELISA appears to be a new reliable method for monitoring the sEH and may be useful as a diagnostic tool for diseases influenced by sEH. This study also demonstrates the broad utility of VHH in biochemical and pharmacological research.

Ordinal Logic Regression: A classifier for discovering combinations of binary markers for ordinal outcomes

In medicine, it is often useful to stratify patients according to disease risk, severity, or response to therapy. Since many diseases arise from complex gene-gene and gene-environment interactions, patient strata may be defined by combinations of genetic and environmental factors. Traditional statistical methods require specifying interactions a priori making it difficult to identify high order interactions. Alternatively, machine learning methods can model complex interactions, however these models are often difficult to interpret in a clinical setting. Logic regression (LR) enables modeling a binary outcome using logical combinations of binary predictors yielding easily interpretable models. However LR, as currently available, cannot model ordinal responses. This paper extends LR to model an ordinal response and the resulting method is called Ordinal Logic Regression (OLR). Several simulations comparing OLR and Classification and Regression Trees (CART) demonstrate that OLR is superior to CART for identifying variable interactions associated with an ordinal response. OLR is applied to data from a study to determine associations between genetic and health factors with severity of adult periodontitis.

TERT genetic polymorphism rs2736100 was associated with lung cancer: a meta-analysis based on 14,492 subjects

BACKGROUND

Previous studies focused on the association of the telomerase reverse transcriptase (TERT) gene polymorphism rs2736100 with lung cancer did not reach the same conclusion. In the present study, we performed a meta-analysis to systematically summarize the possible association between TERT polymorphism rs2736100 and the risk for lung cancer.

METHOD

We conducted a search of case-control studies on the association of TERT with susceptibility to lung cancer in PubMed, EMBASE, ISI Web of Science, Wanfang database in China, and Chinese National Knowledge Infrastructure (CNKI) databases. Data from eligible studies were extracted for meta-analysis. Lung cancer risk associated with rs2736100 was estimated by pooled odds ratios (ORs) and 95% confidence intervals (95% CIs).

RESULTS

Six independent case-control studies on rs2736100 were included in our meta-analysis. Our results showed that rs2736100 was associated with the risk of lung cancer not only in an additive model (OR=1.19, 95% CI: 1.04-1.35; p=0.01), but also in a dominant model (OR=1.14, 95% CI: 1.01-1.28; p=0.03).

CONCLUSIONS

This meta-analysis suggests that rs2736100 is associated with the risk of lung cancer.

Increased lung cancer risk associated with the TERT rs2736100 polymorphism: an updated meta-analysis

The rs2736100 polymorphism in the telomerase reverse transcriptase (TERT) gene has been implicated in lung cancer risk in multiple populations, but the existing evidence lacks statistical power to draw a convincing conclusion. Therefore, the present study was devised to derive a more precise estimation of the association between rs2736100 and lung cancer risk. The PubMed, Embase, and Web of Science databases were comprehensively searched for papers concerning lung cancer risk in relation to rs2736100. Pooled odds ratios (ORs) and the 95 % confidence intervals (CIs) were appropriately calculated using the fixed or random effects model. Meta-analysis of 20 independent studies involving 39,715 cancer cases and 61,462 control subjects showed statistical evidence for an association between rs2736100 and increased risk of lung cancer. Subgroup analysis by ethnicity demonstrated a significant association among both Asian and Caucasian populations. We additionally found an increased risk of non-small cell lung cancer and lung adenocarcinoma strongly associated with rs2736100. These data provide further evidence supporting a role for genetic susceptibility of TERT rs2736100 in the development of lung cancer.

TP53 genetic polymorphisms, interactions with lifestyle factors and lung cancer risk: a case control study in a Chinese population

BACKGROUND

A pathway-based genotyping analysis suggested rs2078486 was a novel TP53 SNP, but very few studies replicate this association. TP53 rs1042522 is the most commonly studied SNP, but very few studies examined its potential interaction with environmental factors in relation to lung cancer risk. This study aims to examine associations between two TP53 single-nucleotide polymorphisms (SNPs) (rs2078486, rs1042522), their potential interaction with environmental factors and risk of lung cancer.

METHODS

A case-control study was conducted in Taiyuan, China. Unconditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (95% CIs). Multiplicative and additive interactions between TP53 SNPs and lifestyle factors were evaluated.

RESULTS

Variant TP53 rs2078486 SNP was significantly associated with elevated lung cancer risk among smokers (OR: 1.70, 95% CI: 1.08 - 2.67) and individuals with high indoor air pollution exposure (OR: 1.51, 95% CI: 1.00-2.30). Significant or borderline significant multiplicative and additive interactions were found between TP53 rs2078486 polymorphism with smoking and indoor air pollution exposure. The variant genotype of TP53 SNP rs1042522 significantly increased lung cancer risk in the total population (OR: 1.57, 95% CI: 1.11-2.21), but there was no evidence of heterogeneity among individuals with different lifestyle factors.

CONCLUSIONS

This study confirmed that TP53 rs2078486 SNP is potentially a novel TP53 SNP that may affect lung cancer risk. Our study also suggested potential synergetic effects of TP53 rs2078486 SNP with smoking and indoor air pollution exposure on lung cancer risk.

Genetic polymorphisms involved in carcinogen metabolism and DNA repair and lung cancer risk in a Japanese population

BACKGROUND

Several components of overall lung carcinogenesis, carcinogen metabolic and DNA repair pathways may be involved in individual genetic susceptibility to lung cancer.

METHODS

We evaluated the role of cytochrome P450 (CYP) 1A1 rs4646903 and rs104894, glutathione S-transferase (GST) M1 and GSTT1 deletion polymorphisms, GSTP1 rs1695, x-ray repair, excision repair cross-complementing group 2 (ERCC2) rs13181, complementing defective in Chinese hamster 1 rs25487, and XRCC3 rs861539 in a case-control study comprising 462 lung cancer cases and 379 controls in a Japanese population. Unconditional logistic regression was used to assess the adjusted odds ratios (OR) and 95% confidence intervals (95% CI).

RESULTS

CYP1A1 rs4646903 (OR = 1.72, 95% CI = 1.25-2.38), rs1048943 (OR = 1.40, 95% CI = 1.02-1.92), the GSTM1 deletion polymorphism (OR = 1.38, 95% CI = 1.01-1.89), GSTP1 rs1695 (OR =1.48, 95% CI = 1.04-2.11), ERCC2 rs13181 (OR = 1.89, 95% CI = 1.28-2.78), and Chinese hamster 1 rs25487 (OR = 1.54, 95% CI = 1.12-2.13) were associated with lung cancer risk whereas the GSTT1 deletion polymorphism and XRCC3 rs861539 were not. A pertinent combination of multiple "at-risk" genotypes of CYP1A1 rs4646903, the GSTM1 deletion polymorphism and ERCC2 rs13181 was at a 5.94-fold (95% CI = 2.77-12.7) increased risk of lung cancer.

CONCLUSIONS

A pertinent combination of multiple at-risk genotypes may detect a high-risk group. Further studies are warranted to verify our findings.

Phenanthrene metabolism in smokers: use of a two-step diagnostic plot approach to identify subjects with extensive metabolic activation

Polycyclic aromatic hydrocarbons (PAHs) in cigarette smoke are among the most likely causes of lung cancer. PAHs require metabolic activation to initiate the carcinogenic process. Phenanthrene (Phe), a noncarcinogenic PAH, was used as a surrogate of benzo[α]pyrene and related PAHs to study the metabolic activation of PAHs in smokers. A dose of 10 μg of deuterated Phe ([D₁₀]Phe) was administered to 25 healthy smokers in a crossover design, either as an oral solution or by smoking cigarettes containing [D₁₀]Phe. Phe was deuterated to avoid interference from environmental Phe. Intensive blood and urine sampling was performed to quantitate the formation of deuterated r-1,t-2,3,c-4-tetrahydroxy-1,2,3,4-tetrahydrophenanthrene ([D₁₀]PheT), a biomarker of the diol epoxide metabolic activation pathway. In both the oral and smoking arms approximately 6% of the dose was metabolically converted to diol epoxides, with a large intersubject variability in the formation of [D₁₀]PheT observed. Two diagnostic plots were developed to identify subjects with large systemic exposure and significant lung contribution to metabolic activation. The combination of the two plots led to the identification of subjects with substantial local exposure. These subjects produced, in one single pass of [D₁₀]Phe through the lung, a [D₁₀]PheT exposure equivalent to the systemic exposure of a typical subject and may be an indicator of lung cancer susceptibility. Polymorphisms in PAH-metabolizing genes of the 25 subjects were also investigated. The integration of phenotyping and genotyping results indicated that GSTM1-null subjects produced approximately 2-fold more [D₁₀]PheT than did GSTM1-positive subjects.

Oxidatively induced DNA damage: mechanisms, repair and disease

Endogenous and exogenous sources cause oxidatively induced DNA damage in living organisms by a variety of mechanisms. The resulting DNA lesions are mutagenic and, unless repaired, lead to a variety of mutations and consequently to genetic instability, which is a hallmark of cancer. Oxidatively induced DNA damage is repaired in living cells by different pathways that involve a large number of proteins. Unrepaired and accumulated DNA lesions may lead to disease processes including carcinogenesis. Mutations also occur in DNA repair genes, destabilizing the DNA repair system. A majority of cancer cell lines have somatic mutations in their DNA repair genes. In addition, polymorphisms in these genes constitute a risk factor for cancer. In general, defects in DNA repair are associated with cancer. Numerous DNA repair enzymes exist that possess different, but sometimes overlapping substrate specificities for removal of oxidatively induced DNA lesions. In addition to the role of DNA repair in carcinogenesis, recent evidence suggests that some types of tumors possess increased DNA repair capacity that may lead to therapy resistance. DNA repair pathways are drug targets to develop DNA repair inhibitors to increase the efficacy of cancer therapy. Oxidatively induced DNA lesions and DNA repair proteins may serve as potential biomarkers for early detection, cancer risk assessment, prognosis and for monitoring therapy. Taken together, a large body of accumulated evidence suggests that oxidatively induced DNA damage and its repair are important factors in the development of human cancers. Thus this field deserves more research to contribute to the development of cancer biomarkers, DNA repair inhibitors and treatment approaches to better understand and fight cancer.

Environmental exposures and rheumatoid arthritis risk

In addition to rapidly burgeoning data regarding novel genetic risk factors, a growing list of environmental exposures have been implicated in rheumatoid arthritis (RA) susceptibility. Cigarette smoking is chief among the many environmental exposures implicated in disease risk, accounting for approximately one in six new cases of RA, with recent results underscoring the central importance of select gene-smoking interactions in RA development. In this review, we examine data linking several environmental exposures with RA risk, including cigarette smoking, other air pollutants and occupational exposures, reproductive/hormonal influences, alcohol consumption, select infections leading to periodontal disease, and dietary factors. Where applicable, we review the current understanding of biologic mechanisms linking these environmental factors to disease risk.

System review and metaanalysis of the relationships between five metabolic gene polymorphisms and colorectal adenoma risk

The relationships between some metabolic (including EPHX1, GSTs and NQO1) gene polymorphisms and colorectal adenoma (CRA) risk have been commonly studied, and no conclusions are available up to now. Therefore, we quantitatively studied the relationships by a metaanalysis. The databases of Medline and Embase were retrieved updated to June 15th, 2011. Crude or adjusted odds ratio (crude OR or adjusted OR) and 95% confidence interval (95%CI) were calculated to present the strength of the associations. Overall, nine case-control studies for EPHX1 Tyr113His and His139Arg, five case-control studies for GSTM1, four studies for GSTP1 Ile105Val, two studies for GSTP1 Ala114Val, six studies for GSTT1 and four studies for NQO1 Pro187Ser were included in this metaanalysis. The results of combined analyses indicated that EPHX1 Tyr113His and His139Arg, GSTT1, GSTM1, GSTP1 Ile105Val and Ala114Val were not associated with CRA risk [crude OR (95%CI): 0.98 (0.90-1.07) and P ( z-test) = 0.65 for EPHX1 His carriers vs. Tyr/Tyr; 1.05 (0.97-1.15) and P ( z-test) = 0.21 for EPHX1 Arg carriers vs. His/His; 1.05 (0.92-1.20) and P ( z-test) = 0.47 for GSTT1 Null vs. Present; 1.01 (0.90-1.13) and P ( z-test) = 0.90 for GSTM1 Null vs. Present; 1.04 (0.92-1.17) and P ( z-test) = 0.56 for G carriers vs. AA for GSTP1 Ile105Val; 0.88 (0.70-1.11) and P ( z-test) = 0.28 for T carriers vs. CC for GSTP1 Ala114Val]. In contrast, Ser allele of NQO1 Ser187Pro might be a modest risk factor for CRA development [1.19 (1.06-1.33) and P ( z-test) = 0.003 for Ser carriers vs. Pro/Pro]. To get more precise evidences, adjusted ORs (95%CI) for EPHX1 Tyr113His, His139Arg, GSTP1 Ile105Val and NQO1 Ser187Pro were also calculated based on adjusted ORs (95%CIs) reported in primary studies. The results still indicated that EPHX1 Tyr113His, His139Arg and GSTP1 Ile105Val were not associated with CRA risk except for NQO1 Ser187Pro. When subgroup analyses were performed for population-based case-control studies or studies in HWE for EPHX1 Tyr113His and His139Arg, and NQO1 Ser187Pro polymorphisms, the results were persistent. Although with modest limitations and biases, this metaanalysis suggests that EPHX1 Tyr113His and His139Arg, GSTT1, GSTM1, GSTP1 Ile105Val and Ala114Val polymorphisms may be not risk factors for CRA development, while Ser allele of NQO1 Ser187 Pro may be a modest risk factor for CRA development, and may be used with other genetic markers for screening CRA in the future.

Development of fluorescent substrates for microsomal epoxide hydrolase and application to inhibition studies

The microsomal epoxide hydrolase (mEH) plays a significant role in the metabolism of numerous xenobiotics. In addition, it has a potential role in sexual development and bile acid transport, and it is associated with a number of diseases such as emphysema, spontaneous abortion, eclampsia, and several forms of cancer. Toward developing chemical tools to study the biological role of mEH, we designed and synthesized a series of absorbent and fluorescent substrates. The highest activity for both rat and human mEH was obtained with the fluorescent substrate cyano(6-methoxy-naphthalen-2-yl)methyl glycidyl carbonate (11). An in vitro inhibition assay using this substrate ranked a series of known inhibitors similarly to the assay that used radioactive cis-stilbene oxide but with a greater discrimination between inhibitors. These results demonstrate that the new fluorescence-based assay is a useful tool for the discovery of structure-activity relationships among mEH inhibitors. Furthermore, this substrate could also be used for the screening chemical library with high accuracy and with a Z' value of approximately 0.7. This new assay permits a significant decrease in labor and cost and also offers the advantage of a continuous readout. However, it should not be used with crude enzyme preparations due to interfering reactions.

A study of DNA damage recognition and repair gene polymorphisms in relation to cancer predisposition and G2 chromosomal radiosensitivity

The previously reported association of the APEX Asp148Glu single nucleotide polymorphism (SNP) with cancer, and the suggestion of associations of the XRCC3 Thr241Met and hOGG1 Ser326Cys SNP sites with G(2) chromosomal radiosensitivity were investigated in a new study of 30 childhood and young adult cancer survivors, their 30 partners, and 55 offspring. An additional SNP, hOGG1 Arg46Gln was also analyzed. Data on G(2) chromosomal radiosensitivity was available on 29 of the families including 53 offspring. No significant associations of genotype with cancer or G(2) chromosomal radiosensitivity were observed.

Lung Cancer Susceptibility and hOGG1 Ser326Cys Polymorphism: A Meta-Analysis

Recent lung cancer studies have focused on identifying the effects of single nucleotide polymorphisms (SNPs) in candidate genes, among which DNA repair genes are increasingly being studied. Genetic variations in DNA repair genes are thought to modulate DNA repair capacity and are suggested to be related to lung cancer risk. In this study, we tried to assess reported studies of association between polymorphism of human 8-oxoguanine DNA glycosylase 1 (hOGG1) Ser326Cys and lung cancer. We conducted MEDLINE, Current Contents and Web of Science searches using "hOGG1", "lung cancer" and "polymorphism" as keywords to search for papers published (from January 1995 through August 2010). Data were combined using both a fixed effects (the inverse variance-weighted method) and a random effects (DerSimonian and Laird method) models. The Cochran Q test was used for the assessment of heterogeneity. Publication bias was assessed by both Begg’s and Egger’s tests. We identified 20 case-control studies in 21 different ethnic populations. As two studies were not in the Hardy-Weinberg equilibrium, 18 case-control studies in 19 different ethnic populations (7,792 cases and 9,358 controls) were included in our meta-analysis. Summary frequencies of the Cys allele among Caucasians and Asians based on the random effects model were 20.9% (95% confidence interval (CI) = 18.9–22.9) and 46.1% (95% CI = 40.2–52.0), respectively. The distribution of the Cys allele was significantly different between Asians and Caucasians (P < 0.001). The Cys/Cys genotype was significantly associated with lung cancer risk in Asian populations (odds ratio = 1.27, 95% CI = 1.09–1.48) but not in Caucasian populations. This ethnic difference in lung cancer risk may be due to environmental factors such as cigarette smoking and dietary factors. Although the summary risk for developing lung cancer may not be large, lung cancer is such a common malignancy that even a small increase in risk can translate to a large number of excess lung cancer cases. As lung cancer is a multifactorial disease, further investigations of the gene-gene and gene-environment interactions on the hOGG1 polymorphism-associated lung cancer risk may help to better understand of the molecular pathogenesis of human lung cancer.

Lung cancer risk and genetic polymorphisms in DNA repair pathways: a meta-analysis

Genetic variations in DNA repair genes are thought to modulate DNA repair capacity and are suggested to be related to lung cancer risk. We conducted a meta-analysis of epidemiologic studies on the association between genetic polymorphisms in both base excision repair and nucleotide excision repair pathways, and lung cancer. We found xeroderma pigmentosum complementation group A (XPA) G23A (odds ratio (OR) = 0.76, 95% confidence interval (CI) = 0.61–0.94), 8-oxoguanine DNA glycosylase 1 (OGG1) Ser326Cys (OR = 1.22, 95% CI = 1.02–1.45), and excision repair cross-complementing group 2 (ERCC2) Lys751Gln (OR = 1.27, 95% CI = 1.10–1.46) polymorphisms were associated with lung cancer risk. Considering the data available, it can be conjectured that if there is any risk association between a single SNP and lung cancer, the risk fluctuation will probably be minimal. Advances in the identification of new polymorphisms and in high-throughput genotyping techniques will facilitate the analysis of multiple genes in multiple DNA repair pathways. Therefore, it is likely that the defining feature of future epidemiologic studies will be the simultaneous analysis of large samples of cases and controls.

Effects of caspase-9 and survivin gene polymorphisms in pancreatic cancer risk and tumor characteristics

OBJECTIVES

This case-control study was performed to evaluate the association between a specific caspase-9 polymorphism as well as the genetic polymorphism -31G/C located in the cycle-dependent elements/cell cycle homology regions repressor element of the human survivin promoter and the risk of pancreatic cancer.

METHODS

Eighty patients with pancreatic cancer and 160 healthy controls were investigated for genotype and allelic frequencies of caspase-9 1263A/G and survivin -31G/C polymorphisms by Polymerase Chain Reaction-Restriction Fragment Length Polymorphism.

RESULTS

The G carrier group of patients and the G allele of caspase-9 1263A/G were overrepresented among the pancreatic cancer cases. With regard to tumor characteristics, a statistically significant association was detected between the survivin C carrier group of patients and the advanced T stage as well as the presence of lymph node metastasis.

CONCLUSIONS

The caspase-9 G allele confers increased susceptibility to pancreatic cancer development, and the survivin C carriage status may be related to aggressive features of this malignancy.

Two loci controlling susceptibility to radiation-induced lymphomagenesis on mouse chromosome 4: cdkn2a, a candidate for one locus, and a novel locus distinct from cdkn2a

BALB/c mice are sensitive to radiation-induced lymphomagenesis, while STS mice are resistant. Using 219 [(BALB/c x STS)F(1) x BALB/c] (N2C) and 197 [(BALB/c x STS)F(1) x STS] (N2S) animals, we performed a genome-wide search for loci controlling susceptibility to lymphomagenesis induced by radiation. Association of markers with the survival of animals was analyzed by the log rank test. For N2C mice, a significant correlation was detected, with four markers on the proximal to mid portion of chromosome 4: D4Mit302 and D4Mit255, P = 0.0075; D4Mit17, P = 0.034; and D4Mit86, P = 0.048. On the other hand, no significant linkage was detected in N2S mice. We analyzed BALB/c mice congenic for the STS allele in different regions of chromosome 4 and identified a locus with a conspicuous effect on survival located within a 7-Mb region between D4Mit302 and D4Mit144, where BALB/c mice harbor hypomorphic variant alleles of the tumor suppressor gene Cdkn2a, which encodes the cyclin-dependent kinase inhibitor protein p16INK4a. Using pooled F(2) intercrosses between the BALB/c and congenic lines carrying the STS allele near D4Mit17, but not in the range from D4Mit302 to D4Mit144, we assigned the second locus to an 11.4-Mb region in the vicinity of D4Mit17. Although Cdkn2a is a likely candidate for the locus controlling susceptibility to lymphomagenesis on chromosome 4, a novel tumor susceptibility gene different from Cdkn2a exists near the primary locus.

Inhalation exposure to ambient polycyclic aromatic hydrocarbons and lung cancer risk of Chinese population

An Euler atmospheric transport model (Canadian Model for Environmental Transport of Organochlorine Pesticides, CanMETOP) was applied and validated to estimate polycyclic aromatic hydrocarbon (PAH) ambient air concentrations at ground level in China based on a high-resolution emission inventory. The results were used to evaluate lung cancer risk for the Chinese population caused by inhalation exposure to PAHs. The uncertainties of the transport model, exposure, and risk analysis were assessed by using Monte Carlo simulation, taking into consideration the variation in PAH emission, aerosol and OH radical concentrations, dry deposition, respiration rate, and genetic susceptibility. The average benzo[a]pyrene equivalent concentration (B[a]P(eq)) was 2.43 [ approximately 1.29-4.50 as interquartile range (IR)] ng/m(3). The population-weighted B[a]P(eq) was 7.64 (IR, approximately 4.05-14.1) ng/m(3) because of the spatial overlap of the emissions and population density. It was estimated that 5.8% (IR, approximately 2.0-11%) of China's land area, where 30% (IR, approximately 17-43%) of the population lives, exceeded the national ambient B[a]P(eq) standard of 10 ng/m(3). Taking into consideration the variation in exposure concentration, respiration rate, and susceptibility, the overall population attributable fraction (PAF) for lung cancer caused by inhalation exposure to PAHs was 1.6% (IR, approximately 0.91-2.6%), corresponding to an excess annual lung cancer incidence rate of 0.65 x 10(-5). Although the spatial variability was high, the lung cancer risk in eastern China was higher than in western China, and populations in major cities had a higher risk of lung cancer than rural areas. An extremely high PAF of >44% was estimated in isolated locations near small-scale coke oven operations.

Cytotoxicity of cigarette smoke condensate is not due to DNA double strand breaks: Comparative studies using radiosensitive mutant and wild-type CHO cells

PURPOSE

To determine whether cigarette smoke condensate (CSC) without metabolic activation induces direct DNA double strand breaks (DSB) in the G1 phase of various radiosensitive mutants of CHO cells and whether these breaks display collateral hypersensitivity to CSC with respect to cell killing.

MATERIALS & METHODS

We treated the G1-phase cultures of wild-type and DNA repair deficient mutants of CHO cells with various concentrations of CSC and examined the cell survival by colony formation assay and the induction of DNA double strand breaks by constant field gel electrophoresis as well as the phophorylated histone H2-A variant X (gamma-H2AX) assay.

RESULTS

Gel analysis and gamma-H2AX focus assay showed significantly fewer, but still detectable levels of DSB per cell after CSC treatment compared to ionizing radiation (IR) exposures, even when equitoxic radiation exposures were delivered at a low dose rate over the same 8-hour exposure used for CSC treatments. None of the three non-homologous end joining (NHEJ) deficient mutants were remarkably hypersensitive to CSC compared to wild-type cells. In contrast, UV-1 cells that are hypersensitive to several base damage and cross-linking agents showed a higher sensitivity to CSC compared to the other CHO cell lines.

CONCLUSIONS

DNA DSB produced directly by CSC are not principally responsible for its cytotoxicity. Further, the present study does not rule out the possibility that some of these lesions may secondarily result in DSB, such as may occur during impeded DNA replication and whose repair may require systems other than NHEJ.

Meta- and pooled analysis of GSTP1 polymorphism and lung cancer: a HuGE-GSEC review

Lung cancer is the most common cancer worldwide. Polymorphisms in genes associated with carcinogen metabolism may modulate risk of disease. Glutathione S-transferase pi (GSTP1) detoxifies polycyclic aromatic hydrocarbons found in cigarette smoke and is the most highly expressed glutathione S-transferase in lung tissue. A polymorphism in the GSTP1 gene, an A-to-G transition in exon 5 (Ile105Val, 313A --> 313G), results in lower activity among individuals who carry the valine allele. The authors present a meta- and a pooled analysis of case-control studies that examined the association between this polymorphism in GSTP1 and lung cancer risk (27 studies, 8,322 cases and 8,844 controls and 15 studies, 4,282 cases and 5,032 controls, respectively). Overall, the meta-analysis found no significant association between lung cancer risk and the GSTP1 exon 5 polymorphism. In the pooled analysis, there was an overall association (odds ratio = 1.11, 95% confidence interval: 1.03, 1.21) between lung cancer and carriage of the GSTP1 Val/Val or Ile/Val genotype compared with those carrying the Ile/Ile genotype. Increased risk varied by histologic type in Asians. There appears to be evidence for interaction between amount of smoking, the GSTP1 exon 5 polymorphism, and risk of lung cancer in whites.

Lifestyle, genes, and cancer

It is estimated that almost 1.5 million people in the USA are diagnosed with cancer every year. However, due to the substantial effect of modifiable lifestyle factors on the most prevalent cancers, it has been estimated that 50% of cancer is preventable. Physical activity, weight loss, and a reduction in alcohol use can strongly be recommended for the reduction of breast cancer risk. Similarly, weight loss, physical activity, and cessation of tobacco use are important behavior changes to reduce colorectal cancer risk, along with the potential benefit for the reduction of red meat consumption and the increase in folic acid intake. Smoking cessation is still the most important prevention intervention for reducing lung cancer risk, but recent evidence indicates that increasing physical activity may also be an important prevention intervention for this disease. The potential benefit of lifestyle change to reduce prostate cancer risk is growing, with recent evidence indicating the importance of a diet rich in tomato-based foods and weight loss. Also, in the cancers for which there are established lifestyle risk factors, such as physical inactivity for breast cancer and obesity for colorectal cancer, there is emerging information on the role that genetics plays in interacting with these factors, as well as the interaction of combinations of lifestyle factors. Integration of genetic information into lifestyle factors can help to clarify the causal relationships between lifestyle and genetic factors and assist in better identifying cancer risk, ultimately leading to better-informed choices about effective methods to enhance health and prevent cancer.

Polymorphisms in the Caspase7 gene and the risk of lung cancer

BACKGROUND

Caspase7 (CASP7) is an executioner CASP that conducted a coordinated program of proteolysis that results in the destruction of critical cell structures, and it plays an important role in the development and progression of cancer. The purpose of this study is to comprehensively evaluate potential functional polymorphisms in the CASP7 gene in relation to the risk of lung cancer.

METHODS

We first captured seven single nucleotide polymorphisms (SNPs) in the regulating region, exons and exon-intron boundaries of the CASP7 gene using public database and then determined their frequencies in 27 healthy Korean individuals. Next, we examined four SNPs (rs12415607g.C>A; rs11593766g.T>G; rs2227310g.C>G; and rs10787498g.T>C) in a case-control study that consisted of 720 lung cancer patients and 720 healthy controls.

RESULTS

Of the four SNPs studied in the case-control study, only the distribution of the rs2227310g.C>G genotypes differed significantly between the cases and controls (P=0.03). The rs2227310 GG genotype was associated with a significantly increased risk of lung cancer when compared with the rs2227310 CC genotype [adjusted odds ratio (OR)=1.42, 95% confidence interval (CI)=1.05-1.93, P=0.02] and with the combined rs2227310 CC and CG genotype (adjusted OR=1.38, 95% CI=1.05-1.81, P=0.02). Consistent with the results of genotyping analysis, the ATGT haplotype (rs12415607A/rs11593766T/rs2227310G/rs10787498T) was associated with a significantly increased risk of lung cancer when compared to other haplotypes (adjusted OR=1.21, 95% CI=1.04-1.42, P=0.02).

CONCLUSION

These results suggest that the CASP7 polymorphisms contribute to the genetic susceptibility to lung cancer.

The genetic polymorphisms of HER-2 and the risk of lung cancer in a Korean population

Background

Human Epidermal Growth Factor Receptor 2 (HER-2; also known as erbB-2 or neu), a proto-oncogene of the receptor tyrosine kinase superfamily, has been associated with carcinogenesis and prognosis of human cancers, acting as a binding partner of other epidermal growth factor receptor (EGFR) family in the activation of EGFR signaling. Amplification of the HER-2 gene has been reported in lung cancer, where it has been associated with poor prognosis. In this study, we investigated whether the four polymorphisms (-3444C>T, -1985 G>T, I655A A>G and P1170A C>G) of the HER-2 gene are associated with the risk of lung cancer in Korean populations.

Methods

The frequencies of 4 polymorphisms of the HER-2 gene were examined by the polymerase chain reaction-restriction fragment length polymorphism or the single-nucleotide polymorphism-identification technology assay in the 407 lung cancer patients and 407 healthy controls.

Results

The frequencies of the 4 polymorphisms were not significantly different between patient and control groups in overall subjects. However, in the subgroup analysis, the 3 single nucleotide polymorphisms (-3444C>T, -1985G>T and P1170A C>G) showed statistically significant differences in the subgroups of females, non-smokers, and non-drinkers (p < 0.05). Additionally, we found the association between the risk of lung cancer and the polymorphisms of HER-2 gene in non-smoker subgroups with adenocarcinoma (p < 0.05).

Conclusion

Our results suggest that the polymorphisms of the HER-2 gene are associated with an increased susceptibility to lung cancer in females, non-smokers and non-drinkers subgroups in the Korean population.

Genetic influences in common respiratory disorders

Respiratory disorders are common problems for adults and children in North America and generally represent the outcome of gene-environment interactions. Some problems are considered genetic in origin, such as cystic fibrosis, and others are considered environmental in origin, such as respiratory infections. Emerging information indicates that even genetic-based disorders are influenced by the environment and that environmental-based disorders are modified by personal genetic factors in individual physiologic responses. An understanding of an individual's personal risk factors for disease or health problem development can allow health care professionals to tailor health promotion strategies and treatment plans with appropriate environmental manipulation. This article explores the genetic influences that may affect the individual's physiologic responses and the consequences of environmental stimuli.

Mammalian heme peroxidases: from molecular mechanisms to health implications

A marked increase in interest has occurred over the last few years in the role that mammalian heme peroxidase enzymes, primarily myeloperoxidase, eosinophil peroxidase, and lactoperoxidase, may play in both disease prevention and human pathologies. This increased interest has been sparked by developments in our understanding of polymorphisms that control the levels of these enzymes, a greater understanding of the basic chemistry and biochemistry of the oxidants formed by these species, the development of specific biomarkers that can be used in vivo to detect damage induced by these oxidants, the detection of active forms of these peroxidases at most, if not all, sites of inflammation, and a correlation between the levels of these enzymes and a number of major human pathologies. This article reviews recent developments in our understanding of the enzymology, chemistry, biochemistry and biologic roles of mammalian peroxidases and the oxidants that they generate, the potential role of these oxidants in human disease, and the use of the levels of these enzymes in disease prognosis.

The TP53 Arg72Pro polymorphism and lung cancer risk in a population of Northern Spain

SUMMARY

Polymorphisms in tumor suppressor genes might contribute to the individual susceptibility to develop different types of cancer. Alterations in genes involved in cell cycle regulation and apoptosis, as tumor suppressor gene TP53, can lead to malignant transformations increasing the risk of developing cancer. We have investigated effects of polymorphism Arg72Pro on lung cancer risk, focusing on smoking and histology. Our study is a hospital-based case-control study designed with 589 lung cancer patients mainly with squamous cell carcinoma (215), adenocarcinoma (156) and small cell carcinoma (90), and 582 control subjects, matched in ethnicity, age and gender. Genotypes were determined by PCR-RFLP and the results were analysed using multivariate unconditional logistic regression, adjusted for age, gender and smoking status. The analysis showed a statistically significant increase of lung cancer risk in Pro carriers (Arg/Pro and Pro/Pro) (adjusted OR=1.32; 95% CI=1.03-1.69), especially for ever smokers (adjusted OR=1.34; 95% CI=1.04-1.73), heavy smokers (adjusted OR=1.48; 95% CI=1.01-2.16) and smokers of exclusively black tobacco (adjusted OR=1.45; 95% CI=1.04-2.00). Moreover, Pro carriers present an increased risk of developing small cell lung cancer (adjusted OR=1.70; 95% CI=1.07-2.69) and cancer in stage IV for NSCLC (adjusted OR=1.56; 95% CI=1.07-2.27). Our results suggest that polymorphism Arg72Pro in tumor suppressor gene TP53 increases the risk of lung cancer. The effect is especially strong for small cell lung cancer (SCLC) and heavy smokers.

Applications of CYP-450 expression for biomonitoring in environmental health

Cytochrome P450s (CYPs) are one of the first steps in the metabolism of xenobiotics, such as polycyclic aromatic hydrocarbons (PAHs), which are bioactivated into carcinogens. As such, changes in CYP expression are potential biomarkers in human biomonitoring applications. For the proper biomonitoring of environmental toxicants, it is important to understand the biological relevance of each biomarker and the associations among the biomarkers for uses as exposure, effects, and susceptibility biomarkers. Here, we have reviewed various aspects of CYPs for biomonitoring environmental health in terms of the CYP substrates, such as PAHs, aromatic amines, benzene/toluene, and tobacco smoking-related nitrosamines. This review also includes association studies between CYP phenotypical alterations and other exposure, susceptibility, and effect biomarkers. The association studies were mainly performed in CYP gene-transfected cells and noninvasive human biospecies, such as urine and peripheral blood. In conclusion, we suggest that phenotypical alterations in CYPs with exposure to environmental toxicants are useful as susceptibility or effect biomarkers, particularly when the phenotype-related genotypes are unknown.

Do genetic factors protect for early onset lung cancer? A case control study before the age of 50 years

BACKGROUND

Early onset lung cancer shows some familial aggregation, pointing to a genetic predisposition. This study was set up to investigate the role of candidate genes in the susceptibility to lung cancer patients younger than 51 years at diagnosis.

METHODS

246 patients with a primary, histologically or cytologically confirmed neoplasm, recruited from 2000 to 2003 in major lung clinics across Germany, were matched to 223 unrelated healthy controls. 11 single nucleotide polymorphisms of genes with reported associations to lung cancer have been genotyped.

RESULTS

Genetic associations or gene-smoking interactions was found for GPX1(Pro200Leu) and EPHX1(His113Tyr). Carriers of the Leu-allele of GPX1(Pro200Leu) showed a significant risk reduction of OR = 0.6 (95% CI: 0.4-0.8, p = 0.002) in general and of OR = 0.3 (95% CI:0.1-0.8, p = 0.012) within heavy smokers. We could also find a risk decreasing genetic effect for His-carriers of EPHX1(His113Tyr) for moderate smokers (OR = 0.2, 95% CI:0.1-0.7, p = 0.012). Considered both variants together, a monotone decrease of the OR was found for smokers (OR of 0.20; 95% CI: 0.07-0.60) for each protective allele.

CONCLUSION

Smoking is the most important risk factor for young lung cancer patients. However, this study provides some support for the T-Allel of GPX1(Pro200Leu) and the C-Allele of EPHX1(His113Tyr) to play a protective role in early onset lung cancer susceptibility.

Association of the EGFR intron 1 CA repeat length with lung cancer risk

Epidermal growth factor receptor (EGFR) plays an important role in the development and progression of lung cancer. A previous report noted that an increased number of polymorphic CA repeats in the first intron of the EGFR gene results in decreased transcriptional activity. To estimate the association of the length of polymorphic CA repeats in intron 1 of the EGFR gene with lung cancer, a case-control study of 176 lung cancer patients and 161 controls was conducted in Caucasians. This case-control study is based on two existing prospective cohorts: the Early Detection Research Network (EDRN) and the Lung Cancer Specialized Program of Research Excellence (SPORE) at the University of Pittsburgh. The frequencies of the SL (one allele>16 repeats), and SS (both allele<or=16 repeats) genotypes were statistically higher among the cases than in the controls (OR: 1.94 and 3.04, 95% CI: 1.16-3.23 and 1.53-6.04, P-value: 0.01 and 0.001, respectively). When the length of EGFR-CA repeat was analyzed by the sum of the number of repeats in two alleles, the frequency of the shorter repeats (sum<or=36) was 79.6% versus 63.4%, respectively, and the frequency of the longer repeats (sum>36) was 20.5% versus 36.7%, for lung cancer cases versus controls. The lower sum of EGFR-CA repeats associated with the risk of lung cancer; the estimated odds ratio was 2.25 with 95% confidence interval: 1.38-3.66 (P=0.001). Associations involving EGFR-CA repeat genotype and EGFR-CA repeat sum remained significant when adjusted for age, gender, and tobacco exposure. Our study, which is preliminary, demonstrates for the first time that shorter EGFR-CA repeats associate with lung cancer risk. The number of EGFR-CA repeats identifies a possible susceptible population to lung cancer.

Myeloperoxidase G-463A polymorphism and lung cancer: a HuGE genetic susceptibility to environmental carcinogens pooled analysis

Myeloperoxidase is a phase I metabolic enzyme that converts the metabolites of benzo[a]pyrene from tobacco smoke into highly reactive epoxides. A polymorphism in the promoter region of myeloperoxidase (463G-->A) has been found to be inversely associated with lung cancer; differences in the association with age and gender have been suggested. We conducted a pooled analysis of individual data from 10 studies (3688 cases and 3874 controls) from the Genetic Susceptibility to Environmental Carcinogens database. The odds ratio for lung cancer was 0.88 (95% confidence interval: 0.80-0.97) for the AG variant of myeloperoxidase G-463A polymorphism, and 0.71 (95% confidence interval: 0.57-0.88) for the AA variant after adjusting for smoking, age, gender, and ethnicity. The inverse association between lung cancer and myeloperoxidase G-463A polymorphism was equally found in males and females (odds ratio for the AA genotype 0.73 [95% confidence interval: 0.56-0.96] and 0.67 [95% confidence interval: 0.46-0.98], respectively), without differences in the association according to age in the two genders. The myeloperoxidase G-463A polymorphism was significantly protective in "ever" smokers but not in "never" smokers. Myeloperoxidase is a key enzyme in tobacco-induced carcinogenesis.