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

Association between CCND1 and XPC polymorphisms and bladder cancer risk: a meta-analysis based on 15 case-control studies

Perturbations in cell cycle and DNA repair genes might affect susceptibility to cancer. The aim of this meta-analysis is to generate large-scale evidence to determine the degree to which common Cyclin D1 (CCND1) G870A (dbSNP: rs603965) and xeroderma pigmentosum group C (XPC) Ala499Val (dbSNP: rs2228000) polymorphisms are associated with susceptibility to bladder cancer. The electronic databases PubMed, Embase, Web of Science, and CNKI were searched for relevant studies (with an upper date limit of July 25, 2013). The principal outcome measure for evaluating the strength of association was crude odds ratios (ORs) along with their corresponding confidence intervals (95%CIs). We found and reviewed nine case-control studies on CCND1 G870A with a total of 6,823 subjects and seven studies on XPC Ala499Val with a total of 7,674 subjects. Our meta-analysis provides evidence that the variant genotype of CCND1 G870A showed a significant association in the occurrence of invasive bladder tumors in former and current smokers. The XPC Ala499Val polymorphism correlated with significant differences between patients and unaffected subjects, but when the groups were stratified by ethnicity, the magnitude of the overall effect was similar only among Caucasian populations. Results from our meta-analysis support the view that the G870A polymorphism may modulate the risk of bladder cancer in conjunction with tobacco smoking and that the Ala499Val polymorphism may contribute to the susceptibility to bladder cancer in Caucasian populations. Our findings, however, warrant larger well-designed studies to investigate the significance of these two polymorphisms as markers of susceptibility to bladder cancer.

The APE1 Asp148Glu polymorphism and colorectal cancer susceptibility: a meta-analysis

BACKGROUND

Published data regarding the association between the APE1 Asp148Glu polymorphism and colorectal cancer susceptibility remained controversial. This meta-analysis of literatures was performed to draw a more precise estimation of the relationship.

MATERIALS AND METHODS

We systematically searched PubMed, Embase, and Web of Science with a time limit of August 19, 2013. Summary odds ratios (ORs) with 95% CIs were used to assess the strength of association between the APE1 Asp148Glu polymorphism and colorectal cancer susceptibility using random-effects model.

RESULTS

A total of eight case-control studies including 2,597 cases and 3,063 controls were included for analysis. Overall, no significant associations were found between the APE1 Asp148Glu polymorphism and colorectal cancer susceptibility for GG vs TT (OR = 1.00, 95% CI = 0.73-1.36, p = 0.00 for heterogeneity), TG vs TT (OR = 1.17, 95% CI = 0.88-1.55, p = 0.00 for heterogeneity), the dominant model GG + TG vs TT (OR = 1.21, 95% CI = 0.91-1.60, p = 0.00 for heterogeneity) nor the recessive model GG vs TG + TT(OR = 0.95, 95% CI = 0.75-1.20, p = 0.02 for heterogeneity). In subgroup analysis, no significant associations were found in the Asian or Caucasian populations.

CONCLUSION

This meta-analysis suggested that the APE1 Asp148Glu polymorphism was not associated with colorectal cancer susceptibility among Asians or Caucasians.

Genetic background and GxE interactions modulate the penetrance of a naturally occurring wing mutation in Drosophila melanogaster

Many genes involved in producing complex traits are incompletely penetrant. One such example is vesiculated, an X-linked gene in Drosophila melanogaster that results in wing defects. To examine the genetic architecture of a complex trait (wings containing vesicles), we placed a naturally occurring variant into multiple autosomal backgrounds and quantified penetrance and expressivity at a range of developmental temperatures. We found significant epistasis, genotype-by-environment interactions, and maternal effects. Sex and temperature effects were modulated by genetic background. The severity of wing phenotypes also varied across different genetic backgrounds, and expressivity was positively correlated with penetrance. We also found evidence of naturally segregating suppressors of vesiculated. These suppressors were present on both the second and third chromosomes, and complex interactions were observed. Taken together, these findings indicate that multiple genetic and environmental factors modulate the phenotypic effects of a naturally occurring vesiculated allele.

Smoking and hOGG1 Ser326Cys polymorphism contribute to lung cancer risk: evidence from a meta-analysis

The human 8-oxoguanine DNA glycosylase (hOGG1) gene plays an important role in the repair of oxidatively damaged DNA base lesions and its functional single nucleotide polymorphisms (SNPs) may alter DNA repair capacity and thus contributes to cancer susceptibility. Numerous studies have investigated the association between hOGG1 Ser326Cys polymorphism and lung cancer susceptibility; however, the conclusions are still inconclusive. We searched eligible publications from MEDLINE, EMBASE, and CBM and performed a meta-analysis to assess the associations between hOGG1 Ser326Cys polymorphism and lung cancer risk. Pooled odds ratios (ORs) and 95 % confidence intervals (CIs) were calculated to estimate risk associations, and false-positive report probability (FPRP) analysis was also carried out to evaluate significant findings. A total of 31 investigations with 10,220 cases and 12,284 controls were identified. When all studies were pooled, a significantly increased overall lung cancer risk was found (Cys/Cys vs. Ser/Ser: OR = 1.24, 95 % CI = 1.05-1.47, P = 0.013; recessive model: OR = 1.22, 95 % CI = 1.05-1.41, P = 0.008, and Cys vs. Ser: OR = 1.11, 95 % CI = 1.02-1.21, P = 0.022), and further stratification analysis showed that the association was stronger in Asians, never smokers, and more-cigarette takers. These results were confirmed by FPRP analysis. Despite some limitations, this meta-analysis provides solid evidence that hOGG1 Ser326Cys polymorphism may contribute to lung cancer risk, particularly for Asian populations, never smokers, and more-cigarette takers. Nevertheless, these findings warrant further validation in single large investigations.

Association between polymorphisms of XRCC1 Arg399Gln and XPD Lys751Gln genes and prognosis of colorectal cancer in a Chinese population

We conducted this study to detect associations between XRCC1 Arg399Gln and XPD Lys751Gln genotypes and survival of colorectal cancer patients treated with 5-FU/oxalipatin chemotherapy. We included 289 Chinese patients with advanced colorectal cancer, who had received 5-FU/oxalipatin chemotherapy as first-line treatment from January 2005 to January 2007. All patients were followed up till Nov. 2011. Genotyping for XRCC1 Arg399Gln and XPD Lys751Gln polymorphisms was based upon duplex polymerase-chain-reaction with the PCR-RFLP method. In our study, we found the XRCC1 399 Gln/Gln genotype to confer significantly higher rates of response to chemotherapy when compared to the Arg/Arg genotype [OR (95% CI)=2.56(1.57-2.55)]. patients with the XPD 751 Gln/Gln genotype had significantly higher rates of response to chemotherapy [OR (95% CI)=1.54(0.87-2.65)] and those with the XRCC1 399 Gln/Gln genotype had a longer average survival time and significantly lower risk of death than did those with the Arg/Arg genotype [HR (95% CI)=0.66(0.36-0.95)]. Similarly, those carrying the XPD 751Gln/Gln genotype had 0.51-fold the risk of death of those with XPD 751Lys/Lys [HR (95% CI)=0.51(0.33-0.94)]. In conclusion, it is suggested that the XRCC1 Arg399Gln and XPD Lys751Gln polymorphisms should be routinely assessed to determine colorectal patients who are more likely to benefit from 5-FU/oxalipatin chemotherapy.

Genetic polymorphisms in RAD23B and XPC modulate DNA repair capacity and breast cancer risk in Puerto Rican women

Studies have shown that DNA repair capacity (DRC) is significantly decreased in breast cancer patients, but the molecular causes of inter-individual variation in DRC are unknown. We hypothesized that genetic variation in the nucleotide excision repair pathway genes can modulate DRC and breast cancer risk in Puerto Rican women. A total of 228 breast cancer cases and 418 controls were recruited throughout Puerto Rico. For all study participants, eight single nucleotide polymorphisms (SNPs) in the genes XPC, XPD, and RAD23B were genotyped using a TaqMan PCR, and the DRC levels of UV induced-DNA damage was measured in peripheral lymphocytes using a host cell reactivation assay. After adjustment for confounders, RAD23B rs1805329 (Ala249Val) was found to be significantly associated with breast cancer risk under all models tested (P < 0.001). There was also a significant association between breast cancer risk and RAD23B rs10739234 (intronic) under the recessive model (P = 0.003, OR: 2.72, 95% CI: 1.40-5.30). In cases, there was a statistically significant difference in mean DRC per genotype for RAD23B rs1805329 (P < 0.001) and XPC rs2607775 (P = 0.002). When we modeled the combined effect of multiple SNPs that each independently affected DRC on cancer risk, we observed incremental augmentations in risk with increasing number of risk genotypes at those loci (P overall model <0.001). The increase in adverse genotypes was also correlated with a progressive decrease in DRC values. Our data indicate an additive effect of the NER SNPs on DRC and breast cancer risk in Puerto Rican women.

Re-overcoming barriers in translating biomarkers to clinical practice

IMPORTANCE OF THE FIELD

Recently, there has been growing evidence for the concept of personalized medicine as the implementation of genomic and molecular information in the delivery of healthcare. In parallel, the identification of biomarkers has become of enormous significance as a prerequisite for individualized intervention regimens.

AREAS COVERED IN THIS REVIEW

Biomarkers are developed to improve prevention, diagnosis or therapeutic outcome of a given disease. Although each application reveals distinct developmental strategies, evidence-based approval of new biomarkers is important for the success of new drugs, diagnostic tests or recommendations in preventive medicine. Current hurdles to bringing biomarkers into clinical practice are reviewed, thereby focusing on adequate approaches to overcome these limitations in the future.

WHAT THE READER WILL GAIN

The reader will get an introduction to strategies resolving actual barriers in clinical biomarker development.

TAKE HOME MESSAGE

The identification of evidence-based biomarkers is crucial for the success of individualized therapeutic approaches. Developmental strategies have to be adapted to clinical need, thereby focusing on biomarker validation in clinical settings as well as on the establishment of standardized biomarker test systems for routine application. Consortia have been established bringing together representatives of government, academia and industry to improve future biomarker development.

Methylenetetrahydrofolate reductase gene C677T polymorphism and lung cancer: an updated meta-analysis

OBJECTIVE

Methylenetetrahydrofolate reductase (MTHFR) catalyzes the metabolism of folate and nucleotides needed for DNA synthesis and repair. Variations in MTHFR functions likely play roles in the etiology of lung cancer (LC). So far, several studies between MTHFR C677T polymorphism and LC provide controversial or inconclusive results.

METHODS

To better assess the purported relationship, we performed a meta-analysis of 14 publications. Eligible studies were identified by searching the Pubmed, Embase, Web of Science and Google Scholar databases. Odds ratios (ORs) with 95% confidence intervals (CIs) were estimated to assess the association.

RESULTS

Overall, no significant association was detected between the MTHFR C677T polymorphism and LC risk, the same as in race subgroup. However, in the stratified analysis by histological type, significantly increased non-small-cell lung cancer (NSCLC) risk was indicated (T-allele vs. C-allele: OR=1.11, 95%CI=1.03-1.19; TT vs. CC: OR=1.24, 95%CI=1.09-1.41; TC vs. CC: OR=1.11, 95%CI=1.03-1.20 and TT+TC vs. CC: OR=1.09, 95%CI=1.03-1.15). At the same time, ever-smokers who carried T-allele (TT+TC) had a 10% decreased LC risk compared with CC genotype carriers.

CONCLUSIONS

Our study provided evidence that the MTHFR 677T null genotype may increase NSCLC risk, however, it may protect ever-smokers against LC risk. Future studies with large sample sizes are warranted to further evaluate this association in more detail.

Genetic variation in a miR-335 binding site in BIRC5 alters susceptibility to lung cancer in Chinese Han populations

Polymorphisms in 3' untranslated region (UTR) of cancer-related genes might affect their regulation by microRNAs (miRNAs) and thereby contribute to carcinogenesis. In this study, we screened single nucleotide polymorphisms (SNPs) in 3' UTR of cancer-related genes and investigated their effects on risk of lung cancer. First, we genotyped seven SNPs in a Chinese Han population with 600 lung cancer patients and 600 matched healthy controls and found that compared with the TT genotype of rs2239680 in 3' UTR of baculoviral IAP repeat containing 5 (BIRC5), C allele was associated with a significantly increased risk of lung cancer and advanced pathologic stage, with the odds ratio for participants carrying the CT or CC genotype being 1.50 [95% confidence interval (CI) 1.20-1.89, P<0.01] and 2.29 (95% CI 1.64-3.18, P<0.01), respectively. These results were further replicated and confirmed in another independent population with 1000 lung cancer cases and 1000 matched healthy controls. In support of the postulation that the 3' UTR SNP may directly affect miRNA-binding site, reporter gene assays indicated BIRC5 was a direct target of miR-335, and the rs2239680 T>C change resulted in altered regulation of BIRC5 expression. Moreover, BIRC5 was over expressed in lung cancer tissues compared with the normal lung tissues, and the protein levels of BIRC5 correlated with SNP genotypes in normal lung tissues. Our findings defined a 3' UTR SNP in human BIRC5 oncogene that may increase individual susceptibility to lung cancer probably by attenuating the interaction between miR-335 and BIRC5.

MYH rs3219476 and rs3219472 polymorphisms and risk of cholangiocarcinoma

Cholangiocarcinoma (CCA) is a rare but devastating malignancy. Up to 90% of patients presenting with CCA have no identifiable risk factors. The base excision repair (BER) pathway has a principal role in the repair of mutations caused by oxidized or reduced bases. The MutY homolog (MUTYH, MYH) is one of the key proteins in the BER pathway, but the role of MYH in the tumorigenesis of CCA is largely unknown. In this study, we investigated the influence of MYH rs3219476 and rs3219472 polymorphisms on CCA incidence. MYH genotypes were detected using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. We found that for rs3219472, compared with subjects carrying the MYH G/G genotype, those with the A/A genotype had a 2.816-fold higher risk of CCA [odds ratio (OR)=2.816, 95% confidence interval (CI)=0.992-7.999, P=0.047). For rs3219476, compared with subjects carrying the MYH T/T genotype, those with the T/G genotype had a reduced risk of CCA (OR=0.359, 95% CI=0.17-0.758, P=0.006). Our findings suggest that since significantly increased CCA risk was found in individuals with a homozygous variant genotype for rs3219472, it may be a biomarker for screening individuals at high risk of developing the disease.

Genetic variability in DNA repair proteins in age-related macular degeneration

The pathogenesis of age-related macular degeneration (AMD) is complex and involves interactions between environmental and genetic factors, with oxidative stress playing an important role inducing damage in biomolecules, including DNA. Therefore, genetic variability in the components of DNA repair systems may influence the ability of the cell to cope with oxidative stress and in this way contribute to the pathogenesis of AMD. However, few reports have been published on this subject so far. We demonstrated that the c.977C>G polymorphism (rs1052133) in the hOGG1 gene and the c.972G>C polymorphism (rs3219489) in the MUTYH gene, the products of which play important roles in the repair of oxidatively damaged DNA, might be associated with the risk of AMD. Oxidative stress may promote misincorporation of uracil into DNA, where it is targeted by several DNA glycosylases. We observed that the g.4235T>C (rs2337395) and c.–32A>G (rs3087404) polymorphisms in two genes encoding such glycosylases, UNG and SMUG1, respectively, could be associated with the occurrence of AMD. Polymorphisms in some other DNA repair genes, including XPD (ERCC2), XRCC1 and ERCC6 (CSB) have also been reported to be associated with AMD. These data confirm the importance of the cellular reaction to DNA damage, and this may be influenced by variability in DNA repair genes, in AMD pathogenesis.

The APE1 Asp/Asp genotype and the combination of APE1 Asp/Asp and hOGG1-Cys variants are associated with increased p53 mutation in non-small cell lung cancer

Background

The hOGG1 Ser326Cys polymorphism is associated with lung cancer risk, but there are limited data regarding an association between the APE1 Asp148Glu polymorphism and lung cancer. Biological evidence shows that the hOGG1-Cys allele results in less DNA repair activity; however, this is not associated with p53 mutation in lung cancer. Therefore, we investigated whether an interaction between hOGG1 and APE1 is associated with the frequency of p53 mutation in lung cancer.

Methods

We studied 217 Taiwanese adults with primary lung cancer. DNA polymorphisms of hOGG1 and APE1 were determined by polymerase chain reaction (PCR)-based restriction fragment length polymorphism. Mutations in p53 exons 5–8 were detected by direct sequencing. Multiple logistic regression was used to estimate odds ratios (ORs) and 95% CIs for the risk of p53 mutation associated with polymorphisms of hOGG1 and APE1 in lung cancer.

Results

As expected, no association between hOGG1 polymorphism and p53 mutation was observed in this population. However, a higher risk of p53 mutation was found in participants with the APE1 Asp/Asp genotype than in those with the APE1-Glu allele (OR, 2.15; 95% CI, 1.19–3.87; P = 0.011). The risk of p53 mutation was also higher in participants with APE1 Asp/Asp plus hOGG1-Cys than in those with APE1-Glu plus hOGG1 Ser/Ser (OR, 3.72; 95% CI, 1.33–10.40; P = 0.012).

Conclusions

These results suggest that the APE1 Asp/Asp genotype and the combination of the APE1 Asp/Asp and hOGG1-Cys variants are associated with increased risk of p53 mutation in non–small cell lung cancer.

Reprint of: gene susceptibility to oxidative damage: from single nucleotide polymorphisms to function

Oxidative damage to DNA can cause mutations, and mutations can lead to cancer. DNA repair of oxidative damage should therefore play a pivotal role in defending humans against cancer. This is exemplified by the increased risk of colorectal cancer of patients with germ-line mutations of the oxidative damage DNA glycosylase MUTYH. In contrast to germ-line mutations in DNA repair genes, which cause a strong deficiency in DNA repair activity in all cell types, the role of single nucleotide polymorphisms (SNPs) in sporadic cancer is unclear also because deficiencies in DNA repair, if any, are expected to be much milder. Further slowing down progress are the paucity of accurate and reproducible functional assays and poor epidemiological design of many studies. This review will focus on the most common and widely studied SNPs of oxidative DNA damage repair proteins trying to bridge the information available on biochemical and structural features of the repair proteins with the functional effects of these variants and their potential impact on the pathogenesis of disease.

The nature of nurture and the future of evodevo: toward a theory of developmental evolution

This essay has three parts. First, I posit that much research in contemporary evodevo remains steeped in a traditional framework that views traits and trait differences as being caused by genes and genetic variation, and the environment as providing an external context in which development and evolution unfold. Second, I discuss three attributes of organismal development and evolution, broadly applicable to all organisms and traits that call into question the usefulness of gene- and genome-centric views of development and evolution. I then focus on the third and main aim of this essay and ask: what conceptual and empirical opportunities exist that would permit evodevo research to transcend the traditional boundaries inherited from its parent disciplines and to move toward the development of a more comprehensive and realistic theory of developmental evolution? Here, I focus on three conceptual frameworks, the theory of facilitated variation, the theory of evolution by genetic accommodation, and the theory of niche construction. I conclude that combined they provide a rich, interlocking framework within which to revise existing and develop novel empirical approaches toward a better understanding of the nature of developmental evolution. Examples of such approaches are highlighted, and the consequences of expanding existing frameworks are discussed.

Screening for Familial Colorectal Cancer Risk amongst Colonoscopy Patients New to an Open-Access Endoscopy Center

Purpose. We evaluated a questionnaire to aid in the recognition of CRC risk, as well as patient interest in their risk status within an open-access endoscopy center. Methods. A questionnaire was administered to new patients presenting for colonoscopy from May 2007 to February 2008. 287 patients were enrolled. Family history was evaluated using Amsterdam 1, II, and Revised Bethesda criteria. Recognition of risk and referral for counseling was assessed. Patients' interest to be contacted by a genetic counselor was also assessed. Results. 13.2 % (38/287) of patients met Revised Bethesda criteria. Of these, 18 (47.4 %) were previously told about their increased risk for CRC. Only 1 patient who met Revised Bethesda criteria (2.6 %) was previously referred for genetics, whereas none of the 3 patients who met Amsterdam I or II criteria were referred. 23.7 % of high-risk patients did not want to be contacted if found to be at increased risk for cancer. Conclusion. In our open-access endoscopy system, a significant number of high-risk patients remain unidentified and underreferred for genetic counseling due to numerous barriers. Our findings lend support to taking a public health approach to identifying those at risk for Lynch syndrome by implementing universal screening of all CRC specimens.

Gene susceptibility to oxidative damage: from single nucleotide polymorphisms to function

Oxidative damage to DNA can cause mutations, and mutations can lead to cancer. DNA repair of oxidative damage should therefore play a pivotal role in defending humans against cancer. This is exemplified by the increased risk of colorectal cancer of patients with germ-line mutations of the oxidative damage DNA glycosylase MUTYH. In contrast to germ-line mutations in DNA repair genes, which cause a strong deficiency in DNA repair activity in all cell types, the role of single nucleotide polymorphisms (SNPs) in sporadic cancer is unclear also because deficiencies in DNA repair, if any, are expected to be much milder. Further slowing down progress are the paucity of accurate and reproducible functional assays and poor epidemiological design of many studies. This review will focus on the most common and widely studied SNPs of oxidative DNA damage repair proteins trying to bridge the information available on biochemical and structural features of the repair proteins with the functional effects of these variants and their potential impact on the pathogenesis of disease.

Catechol-O-methyltransferase Val 108/158 Met polymorphism and breast cancer risk: a case control study in Syria

BACKGROUND

Catechol-O-methyltransferase (COMT) inactivates catechol estrogens by methylation and thus may play a protective role against mutations induced by estrogen metabolites. In this study we investigated the relationship between the Vall58Met polymorphism in the COMT gene and breast cancer risk in a population-based case control study in Syria.

METHODS

We examined 135 breast cancer patients and 107 healthy controls in North Syria to determine the association between the functional genetic Val158Met polymorphism in the COMT gene and female breast cancer risk.

RESULTS

There was no significant overall association between the COMT genotype and individual susceptibility to breast cancer.

CONCLUSIONS

Our data suggest that there may be no overall association between the COMT genotype and breast cancer.

Lack of association between XPD Lys751Gln and Asp312Asn polymorphisms and colorectal cancer risk: a meta-analysis of case-control studies

PURPOSE

The published data on the association between xeroderma pigmentosum group D (XPD) Lys751Gln and Asp312Asn polymorphisms and colorectal cancer remained controversial. The present meta-analysis of literatures was performed to derive a more precise estimation of the relationship.

MATERIALS AND METHODS

A comprehensive literature search was conducted to identify all case-control studies of Lys751Gln and Asp312Asn polymorphisms on the susceptibility of different tumor site of colorectal cancer (colon, rectum, and colon/rectum cancer). A total of 22 eligible studies were selected for this meta-analysis, including 3,042 cases and 4,627 controls for Lys751Gln and 1,581 cases and 2,846 controls for Asp312Asn.

RESULTS

Overall, no significantly elevated colorectal cancer risk was found in all genetic models when all studies were pooled into the meta-analysis (for Lys751Gln polymorphism: Lys/Gln vs. Lys/Lys, OR = 1.01, 95% CI = 0.90-1.14; Gln/Gln vs. Lys/Lys, OR = 1.04, 95% CI = 0.85-1.26; dominant model, OR = 1.03, 95% CI = 0.93-1.15; recessive model, OR = 1.04, 95% CI = 0.87-1.25; and for Asp312Asn polymorphism: Asp/Asn vs. Asp/Asp, OR = 1.11, 95% CI = 0.91-1.35; Asn/Asn vs. Asp/Asp, OR = 1.13, 95% CI = 0.87-1.47; dominant model, OR = 1.09, 95% CI = 0.94-1.26; recessive model, OR = 1.11, 95% CI = 0.88-1.41). And for the additive model, individuals carrying the 751Gln or 312Asn allele were not significantly associated with increased risk to colorectal cancer (OR = 1.02, 95% CI = 0.94-1.11, OR = 1.07, 95% CI = 0.95-1.20).

CONCLUSION

This meta-analysis suggests that XPD Lys751Gln and Asp312Asn polymorphisms may not be associated with colorectal cancer development.

Personalized medicine: new genomics, old lessons

Personalized medicine uses traditional, as well as emerging concepts of the genetic and environmental basis of disease to individualize prevention, diagnosis and treatment. Personalized genomics plays a vital, but not exclusive role in this evolving model of personalized medicine. The distinctions between genetic and genomic medicine are more quantitative than qualitative. Personalized genomics builds on principles established by the integration of genetics into medical practice. Principles shared by genetic and genomic aspects of medicine, include the use of variants as markers for diagnosis, prognosis, prevention, as well as targets for treatment, the use of clinically validated variants that may not be functionally characterized, the segregation of these variants in non-Mendelian as well as Mendelian patterns, the role of gene--environment interactions, the dependence on evidence for clinical utility, the critical translational role of behavioral science, and common ethical considerations. During the current period of transition from investigation to practice, consumers should be protected from harms of premature translation of research findings, while encouraging the innovative and cost-effective application of those genomic discoveries that improve personalized medical care.

An association study of polymorphisms in JAK3 gene with lung cancer in the Korean population

Purpose

The genetic alteration of the janus kinases (JAKs), non-receptor tyrosine kinase, is related to the development of human cancers. However, little is known about how the sequence variation of JAK3 contributes to the development of lung cancer. This study investigated whether polymorphisms at the promoter region of the JAK3 gene are associated with the risk of lung cancer in the Korean population.

Materials and Methods

A total of 819 subjects, including 409 lung cancer patients and 410 healthy controls were recruited. The SNaPshot assay and polymerase chain reaction-restriction fragment length polymorphism analysis were used, and logistic regression analyses were performed to characterize the association between polymorphisms of JAK3 and lung cancer risk.

Results

Three polymorphisms (-672 G>A, +64 A>G and +227 G>A) of JAK3 were analyzed for large-scale genotyping (n=819). Statistical analyses revealed that polymorphisms and haplotypes in the JAK3 gene were not significantly associated with lung cancer.

Conclusion

JAK3 gene was not significantly associated with the risk of lung cancer in the Korean population.

DNA repair genes polymorphism (XPG and XRCC1) and association of prostate cancer in a north Indian population

Prostate cancer is the most commonly diagnosed cancer in men worldwide and is the second leading cause of cancer related mortality. Genetic background may account for the difference in susceptibility of individuals to different diseases and the relationship between genetic polymorphism and some diseases has been extensively studied. There are several common polymorphisms in genes encoding DNA repair enzymes, some of these polymorphisms are reported to result in subtle structural alterations of the repair enzyme and modulation of the repair capacity. The aim of the present study was to analyze the effect of XPG Asp 1104His and XRCC1 Arg309Gln polymorphisms on risk of prostate cancer in north Indian population. Statistically significant increased risk of prostate cancer was observed on individuals that posses His/His genotype of XPG (OR 2.53, 95% CI 0.99-6.56, P = 0.031). In this study 150 prostate cancer diagnosed patients, 150 healthy controls and 150 BPH (benign prostate hyper plasia) were recruited from north Indian population. Moreover, individuals that carried the Gln/Gln genotype of XRCC1 also showed statistically increased risk of prostate cancer (OR 2.06, 95% CI 1.07-4.00, P = 0.033). The Asp/Asp of XPG and Gln/Gln of XRCC1 in combination showed statistically increased risk of prostate cancer in cases (OR 3.29, 95% CI 1.09-10.16, P = 0.032).

The Ku70 -1310C/G promoter polymorphism is associated with breast cancer susceptibility in Chinese Han population

Ku70 plays an important role in the DSBR (DNA double-strand breaks repair) and maintenance of genomic integrity. Genetic variations within human Ku70 have been demonstrated to be associated with increased risk of several types of cancers. In this hospital-based case-control study, we aimed to investigate whether a single nucleotide polymorphism (SNP) in the promoter region (rs2267437) of Ku70 gene is associated with susceptibility to breast cancer in Chinese Han population. A total of 293 patients with breast cancer and 301 age-matched healthy controls were enrolled in this study. The Ku70 -1310C/G polymorphism was determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis. A significant difference in genotype distribution and allele frequency was observed between patients and controls. The CG or GG carries were at higher risk of breast cancer compared with the CC homozygotes (OR=1.43, 95% CI=1.02-2.00, P=0.038 and OR=3.53, 95% CI=1.60-7.80, P=0.002, respectively). Further stratification analysis revealed that G allele was associated with an increased risk of breast cancer among premenopausal women (OR=1.68, 95% CI=1.21-2.33, P=0.002), but not in postmenopausal women (OR=1.33, 5% CI=0.85-2.10, P=0.216). Our study suggests that the Ku70 -1310C/G promoter polymorphism may be a susceptibility factor for breast cancer in Chinese Han population.

Role of the XRCC5/XRCC6 dimer in carcinogenesis and pharmacogenomics

Over the past few decades, the incidence of cancer has rapidly increased all over the world and cancer remains a major threat to public health. It is believed that cancer results from a series of genetic alterations that lead to the progressive disorder of the normal mechanisms controlling cell proliferation, differentiation, death and/or genomic stability. The response of the cell to genetic injury and its ability to maintain genomic stability by means of a variety of DNA repair mechanisms are therefore essential in preventing tumor initiation and progression. From the same viewpoint, the relative role of DNA repair as a biomarker for prognosis, predictor of drug and therapy responses or indeed as a target for novel gene therapy, is very promising. In this article, we have summarized the studies investigating the association between the XRCC5/XRCC6 dimer and the susceptibility to multiple cancers and discuss its role in carcinogenesis and its potential application to anticancer drug discovery.

Methylenetetrahydrofolate reductase C677T polymorphism in patients with lung cancer in a Korean population

Background

This study was designed to investigate an association between methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and the risk of lung cancer in a Korean population.

Methods

We conducted a large-scale, case-control study involving 3938 patients with newly diagnosed lung cancer and 1700 healthy controls. Genotyping was performed with peripheral blood DNA for MTHFR C677T polymorphisms. Statistical significance was estimated by logistic regression analysis.

Results

The MTHFR C677T frequencies of CC, CT, and TT genotypes were 34.5%, 48.5%, and 17% among lung cancer patients, and 31.8%, 50.7%, and 17.5% in the controls, respectively. The MTHFR 677CT and TT genotype showed a weak protection against lung cancer compared with the homozygous CC genotype, although the results did not reach statistical significance. The age- and gender-adjusted odds ratio (OR) of overall lung cancer was 0.90 (95% confidence interval (CI), 0.77-1.04) for MTHFR 677 CT and 0.88 (95% CI, 0.71-1.07) for MTHFR 677TT. However, after stratification analysis by histological type, the MTHFR 677CT genotype showed a significantly decreased risk for squamous cell carcinoma (age- and gender-adjusted OR, 0.78; 95% CI, 0.64-0.96). The combination of 677 TT homozygous with 677 CT heterozygous also appeared to have a protection effect on the risk of squamous cell carcinoma. We observed no significant interaction between the MTHFR C677T polymorphism and age and gender or smoking habit.

Conclusions

This is the first reported study focusing on the association between MTHFR C677T polymorphisms and the risk of lung cancer in a Korean population. The T allele was found to provide a weak protective association with lung squamous cell carcinoma.

Individual and cumulative effects of GWAS susceptibility loci in lung cancer: associations after sub-phenotyping for COPD

Epidemiological studies show that approximately 20–30% of chronic smokers develop chronic obstructive pulmonary disease (COPD) while 10–15% develop lung cancer. COPD pre-exists lung cancer in 50–90% of cases and has a heritability of 40–77%, much greater than for lung cancer with heritability of 15–25%. These data suggest that smokers susceptible to COPD may also be susceptible to lung cancer. This study examines the association of several overlapping chromosomal loci, recently implicated by GWA studies in COPD, lung function and lung cancer, in (n = 1400) subjects sub-phenotyped for the presence of COPD and matched for smoking exposure. Using this approach we show; the 15q25 locus confers susceptibility to lung cancer and COPD, the 4q31 and 4q22 loci both confer a reduced risk to both COPD and lung cancer, the 6p21 locus confers susceptibility to lung cancer in smokers with pre-existing COPD, the 5p15 and 1q23 loci both confer susceptibility to lung cancer in those with no pre-existing COPD. We also show the 5q33 locus, previously associated with reduced FEV₁, appears to confer susceptibility to both COPD and lung cancer. The 6p21 locus previously linked to reduced FEV₁ is associated with COPD only. Larger studies will be needed to distinguish whether these COPD-related effects may reflect, in part, associations specific to different lung cancer histology. We demonstrate that when the “risk genotypes” derived from the univariate analysis are incorporated into an algorithm with clinical variables, independently associated with lung cancer in multivariate analysis, modest discrimination is possible on receiver operator curve analysis (AUC = 0.70). We suggest that genetic susceptibility to lung cancer includes genes conferring susceptibility to COPD and that sub-phenotyping with spirometry is critical to identifying genes underlying the development of lung cancer.

Polymorphisms of MLH1 and MSH2 genes and the risk of lung cancer among never smokers

Mismatch repair (MMR) plays an important role in repairing nucleotide mismatches during DNA replication. Defects in MMR genes are associated with some sporadic tumors. MLH1 and MSH2 are two of the MMR genes. We conducted a case-control study to investigate the associations between the risk of lung cancer and genetic polymorphisms in the MLH1 and MSH2 genes. The SNP genotypes were determined in 730 lung cancer patients and 730 healthy controls that were frequency matched for the age, gender, and smoking status. Among the SNP polymorphisms, -93A>G (rs1800734), which is located in the promoter region of MLH1, was significantly associated with the risk of lung cancer. The GG genotype for MLH1 -93A>G was associated with a significantly increased risk of lung cancer compared with the AA genotype among the never-smoking group (adjusted OR=1.64, 95% CI=1.10-2.44; P=0.013). Consistently, the haplotype of MLH1 with one -93G risk allele was associated with the risk of lung cancer compared with the AA haplotype among the never-smoking group. Furthermore, the risk of MLH1 -93A>G polymorphism in the never-smoking group related to lung adenocarcinoma was modulated by environmental tobacco smoke (ETS) exposure status, with a significant gene-ETS interaction (P=0.042). No evidence was found of the association between MSH2 and the lung cancer risk. In conclusion, our data suggest that the MLH1 -93A>G polymorphism may contribute to the etiology of lung cancer, particularly in never smokers. This study also suggests that MLH1 -93A>G polymorphisms and ETS exposure have a role in the tumorigenesis of lung adenocarcinoma among never smokers.

Glutathione S-transferase T1 gene deletion polymorphism and lung cancer risk in Chinese population: a meta-analysis

Genetic variations in metabolic genes are considered to modulate metabolic process of carcinogens and are suggested to be related to cancer risk. However, epidemiological results are not always consistent. In this meta-analysis, we evaluated reported studies of association between polymorphism of glutathione S-transferase T1 gene (GSTT1) and the risk of lung cancer in Chinese population. We found an increased lung cancer risk among subjects carrying GSTT1 null genotype [odds ratio (OR)=1.36, 95 percent confidence interval (95% CI): 1.09-1.69], using 1625 cases and 2188 controls from 11 studies. We also observed an increased risk of lung cancer among null genotype carriers in squamous cell carcinoma and adenocarcinoma, and on the basis of population control in stratified analyses. The meta-analysis suggests that GSTT1 deletion polymorphisms may have an effect on the susceptibility of lung cancer in Chinese population, and a study with the larger sample size is needed to further evaluate gene-gene and gene-environment interaction on GSTT1 deletion polymorphisms and lung cancer risk in Chinese population.

Elevated lung cancer risk is associated with deficiencies in cell cycle checkpoints: genotype and phenotype analyses from a case-control study

Cell cycle checkpoints play critical roles in the maintenance of genomic integrity and inactivation of checkpoint genes are frequently perturbed in most cancers. In a case-control study of 299 non-small cell lung cancer cases and 550 controls in Baltimore, we investigated the association between gamma-radiation-induced G(2)/M arrest in cultured blood lymphocytes and lung cancer risk, and examined genotype-phenotype correlations between genetic polymorphisms of 20 genes involving in DNA repair and cell cycle control and gamma-radiation-induced G(2)/M arrest. The study was specifically designed to examine race and gender differences in risk factors. Our data indicated that a less efficient DNA damage-induced G(2)/M checkpoint was associated with an increased risk of lung cancer in African American women with an adjusted odds ratio (OR) of 2.63 (95% CI = 1.01-7.26); there were no statistically significant associations for Caucasians, or African American men. When the African American women were categorized into quartiles, a significant reverse trend of decreased G(2)/M checkpoint function and increased lung cancer risk was present, with lowest-vs.-highest quartile OR of 13.72 (95% CI = 2.30-81.92, p(trend) < 0.01). Genotype-phenotype correlation analysis indicated that polymorphisms in ATM, CDC25C, CDKN1A, BRCA2, ERCC6, TP53, and TP53BP1 genes were significantly associated with the gamma-radiation-induced G(2)/M arrest phenotype. This study provides evidence that a less efficient G(2)/M checkpoint is significantly associated with lung cancer risk in African American women. The data also suggested that the function of G(2)/M checkpoint is modulated by genetic polymorphisms in genes involved in DNA repair and cell cycle control.

Functional promoter -1271G>C variant of HSPB1 predicts lung cancer risk and survival

PURPOSE Heat-shock protein 27 (Hsp27), encoded by HSPB1, plays crucial roles in tumorigenesis and cell survival and is reported to be an independent prognosis marker for cancer. We hypothesized that genetic variants of the HSPB1 gene may be associated with lung cancer susceptibility and survival. PATIENTS AND METHODS We first resequenced the full-length HSPB1 gene and then genotyped three selected tag single nucleotide polymorphisms (SNPs) in 1,152 paired Chinese lung cancer patient cases and controls. Another 500 paired patient cases and controls were used for replication. We also evaluated the roles of these tagSNPs in the overall survival of 248 patients with advanced non-small-cell lung cancer (NSCLC), and validated the results in another 335 patients with advanced NSCLC. The genotype-phenotype correlation was assessed in 309 workers with occupational exposure to polycyclic-aromatic hydrocarbons (PAHs) as well as by luciferase reporter assay and Western blotting analysis. RESULTS The -1271C allele was associated with a significantly increased lung cancer risk in the two independent patient case-control studies (P < .05 for both), but it conferred a favorable survival for patients with advanced NSCLC in two independent cohorts (adjusted hazard ratio, 0.66 and 0.75, respectively). The occupational PAH-exposed workers carrying the -1271C allele showed higher DNA damage levels than those with the -1271G allele (P = .027). Furthermore, the -1271C allele significantly decreased luciferase activity in four cell lines and resulted in lower Hsp27 expression levels in normal lung tissues when compared with -1271G allele (P < .05). CONCLUSION The functional HSPB1 promoter -1271G>C variant may affect lung cancer susceptibility and survival by modulating endogenous Hsp27 synthesis levels.

Lung cancer susceptibility among atomic bomb survivors in relation to CA repeat number polymorphism of epidermal growth factor receptor gene and radiation dose

Lung cancer is a leading cause of cancer death worldwide. Prevention could be improved by identifying susceptible individuals as well as improving understanding of interactions between genes and etiological environmental agents, including radiation exposure. The epidermal growth factor receptor (EGFR)-signaling pathway, regulating cellular radiation sensitivity, is an oncogenic cascade involved in lung cancer, especially adenocarcinoma. The cytosine adenine (CA) repeat number polymorphism in the first intron of EGFR has been shown to be inversely correlated with EGFR production. It is hypothesized that CA repeat number may modulate individual susceptibility to lung cancer. Thus, we carried out a case-cohort study within the Japanese atomic bomb (A-bomb) survivor cohort to evaluate a possible association of CA repeat polymorphism with lung cancer risk in radiation-exposed or negligibly exposed (<5 mGy) A-bomb survivors. First, by dividing study subjects into Short and Long genotypes, defined as the summed CA repeat number of two alleles < or = 37 and > or = 38, respectively, we found that the Short genotype was significantly associated with an increased risk of lung cancer, specifically adenocarcinoma, among negligibly exposed subjects. Next, we found that prior radiation exposure significantly enhanced lung cancer risk of survivors with the Long genotype, whereas the risk for the Short genotype did not show any significant increase with radiation dose, resulting in indistinguishable risks between these genotypes at a high radiation dose. Our findings imply that the EGFR pathway plays a crucial role in assessing individual susceptibility to lung adenocarcinoma in relation to radiation exposure.

ATM polymorphisms and risk of lung cancer among never smokers

The ataxia-telangiectasia mutated (ATM) gene, an important caretaker of overall genome stability, is thought to play a role in the development of human malignancy. Therefore, we hypothesized that sequence variants in ATM may influence the disposition to lung cancer. In this hospital-based matched case-control study, nine ATM single nucleotide polymorphisms (rs189037, rs228597, rs228592, rs664677, rs609261, rs599558, rs609429, rs227062, and rs664982) were genotyped in 730 lung cancer patients and 730 healthy controls. Pairwise linkage disequilibrium among nine polymorphisms in the ATM gene was very high. None of the main effects of any of the ATM polymorphisms were related to the risk of lung cancer. Interestingly, ATM polymorphisms were significantly associated with lung cancer among never smokers, and the association was modulated by low-level exposure to carcinogens such as environmental tobacco smoke. When the haplotypes of nine ATM polymorphism sites were studied, no overall association between ATM haplotypes and risk of lung cancer was found. However, the frequency distribution of haplotypes between lung cancer cases and controls was significant in the never smokers (P=0.009), demonstrating that haplotypes have a significant effect on the risk of lung cancer. In conclusion, we found that never smokers with sequence variants of the ATM gene may be at increased risk for lung cancer. Our data also suggest this association may be further modified by exposure to environmental tobacco smoke. This study suggests support to the literature that ATM polymorphisms and environmental tobacco smoke exposure have a role in lung carcinogenesis among never smokers.

Information-theoretic gene-gene and gene-environment interaction analysis of quantitative traits

Background

The purpose of this research was to develop a novel information theoretic method and an efficient algorithm for analyzing the gene-gene (GGI) and gene-environmental interactions (GEI) associated with quantitative traits (QT). The method is built on two information-theoretic metrics, the k-way interaction information (KWII) and phenotype-associated information (PAI). The PAI is a novel information theoretic metric that is obtained from the total information correlation (TCI) information theoretic metric by removing the contributions for inter-variable dependencies (resulting from factors such as linkage disequilibrium and common sources of environmental pollutants).

Results

The KWII and the PAI were critically evaluated and incorporated within an algorithm called CHORUS for analyzing QT. The combinations with the highest values of KWII and PAI identified each known GEI associated with the QT in the simulated data sets. The CHORUS algorithm was tested using the simulated GAW15 data set and two real GGI data sets from QTL mapping studies of high-density lipoprotein levels/atherosclerotic lesion size and ultra-violet light-induced immunosuppression. The KWII and PAI were found to have excellent sensitivity for identifying the key GEI simulated to affect the two quantitative trait variables in the GAW15 data set. In addition, both metrics showed strong concordance with the results of the two different QTL mapping data sets.

Conclusion

The KWII and PAI are promising metrics for analyzing the GEI of QT.

Basic properties and molecular mechanisms of exogenous chemical carcinogens

Exogenous chemical carcinogenesis is an extremely complex multifactorial process during which gene-environment interactions involving chronic exposure to exogenous chemical carcinogens (ECCs) and polymorphisms of cancer susceptibility genes add further complexity. We describe the properties and molecular mechanisms of ECCs that contribute to induce and generate cancer. A basic and specific property of many lipophilic organic ECCs including polycyclic aromatic hydrocarbons and polyhalogenated aromatic hydrocarbons is their ability to bioaccumulate in the adipose tissue from where they may be released in the blood circulation and target peripheral tissues for carcinogenesis. Many organic ECCs are procarcinogens and consequently need to be activated by the cytochrome P450 (CYP) system and/or other enzymes before they can adduct DNA and proteins. Because they contribute not only to the cocarcinogenic and promoting effects of many aromatic pollutants but also to their mutagenic effects, the aryl hydrocarbon receptor-activating and the inducible CYP systems are central to exogenous chemical carcinogenesis. Another basic property of ECCs is their ability to induce stable and bulky DNA adducts that cannot be simply repaired by the different repair systems. In addition, following ECC exposure, mutagenesis may also be caused indirectly by free-radical production and by epigenetic alterations. As a result of complex molecular interplays, direct and/or indirect mutagenesis may especially account for the carcinogenic effects of many exogenous metals and metalloids. Because of these molecular properties and action mechanisms, we conclude that ECCs could be major contributors to human cancer, with obviously great public health consequences.

Common polymorphisms in the XPD and hOGG1 genes are not associated with the risk of colorectal cancer in a Polish population

Mutations in the DNA repair genes may contribute to the increased risk of cancer, including colorectal cancer. Xeroderma pigmentosum group D (XPD) protein and human homolog of the 8-oxoguanine glycosylase 1 (hOGG1) are involved in nucleotide excision repair and base excision repair, respectively. The XPD and the hOGG1 genes are highly polymorphic, and some of their polymorphisms are associated with several types of cancers. However, there is controversy as to the relationship between their polymorphisms and the risk of colorectal cancer. In the present study, we therefore searched for the association in a Polish population between colorectal cancer and two common polymorphisms: an A --> C transversion in the XPD gene that produces a Lys-to-Gln substitution at codon 751 (the Lys751Gln polymorphism; rs28365048) and a C --> G transversion in the hOGG1 gene resulting in a Ser-to-Cys change at codon 326 (the Ser326Cys polymorphism; rs1052133). Genotypes were determined using peripheral blood lymphocytes of 100 colorectal cancer patients and 100 age-, sex- and ethnicity-matched cancer-free controls by PCR and restriction fragment-length polymorphism analysis. We did not find statistically significant association between each polymorphism and the occurrence of colorectal cancer, and did not observe any relationship between each polymorphism and colorectal cancer progression assessed by node metastasis, tumor size and Duke's stage. Moreover, there was no correlation between combined genotypes of the two polymorphisms and colorectal cancer. Therefore, the Lys751Gln polymorphism of the XPD gene and the Ser326Cys polymorphism of the hOGG1 gene are not associated with colorectal cancer in a Polish population.

Environmental tobacco smoke (ETS) and respiratory health in children

Environmental tobacco smoke (ETS) is a major risk factor for poor lung health in children. Although parental smoking is the commonest source of ETS exposure to children, they are also exposed to ETS in schools, restaurants, public places and public transport vehicles. Apart from containing thousands of chemicals, the particle size in the ETS is much smaller than the main stream smoke, and therefore has a greater penetrability in the airways of children. Exposure to ETS has been shown to be associated with increased prevalence of upper respiratory tract infections, wheeze, asthma and lower respiratory tract infections. Even developing fetuses are exposed to ETS via the umbilical cord blood if the mother is exposed to tobacco smoke. The placenta also does not offer any barrier to the penetration of ETS into the fetus. The immune system in these babies is more deviated toward the allergic and asthmatic inflammatory phenotype and therefore makes them more prone to develop asthma later in life. An increased awareness of the harmful effects of ETS on children's health is warranted.

Lung cancer susceptibility and prognosis associated with polymorphisms in the nonhomologous end-joining pathway genes: a multiple genotype-phenotype study

BACKGROUND

Nonsmall cell lung cancer (NSCLC) frequently exhibits genomic instability, such as high fractional allelic loss (FAL). Genomic instability may result from unrepaired or misrepaired double-strand breaks (DSBs). The authors of this report postulated that polymorphisms in genes of the nonhomologous end-joining (NHEJ) pathway, which is the major DSB repair pathway in mammalian cells, may modulate lung cancer susceptibility and prognosis.

METHODS

Patients with NSCLC (n = 152) and a group of appropriate age-matched and sex-matched controls (n = 162) were subjected to genotype analysis of the NHEJ pathway genes x-ray repair complementing defective repair in Chinese hamster cells 6 (Ku70) (reference single nucleotide polymorphism number [rs] 2267437), x-ray repair complementing defective repair in Chinese hamster cells 5 (Ku80) (rs3835), x-ray repair complementing defective repair in Chinese hamster cells 4 (XRCC4) (rs1805377), and DNA ligase IV (LIG4) (rs1805388). The gene-gene interaction (joint effect), genotype-environmental (ie, smoking) correlation, and genotype-phenotype (ie, FAL) correlation were examined. The Kaplan-Meier method and log-rank tests were used to assess the prognostic effect.

RESULTS

There was a significant association between the XRCC4 and LIG4 genotypes with NSCLC risk in an analysis of individual polymorphism associations, and the risk of NSCLC increased further in a combined analysis of multiple polymorphisms (adjusted odds ratio [OR], 8.74). The patients who had a homozygous variant guanine/guanine genotype of the XRCC4 gene had a poorer prognosis compared with other patients (P = .015). There was a significant difference between the patient smokers and controls for XRCC4 (adjusted OR, 2.67) and LIG4 (adjusted OR, 2.04). In addition, polymorphisms in XRCC4 and LIG4 were linked significantly with patients who had high FAL (adjusted OR, 2.03-3.84).

CONCLUSIONS

To the authors' knowledge, this is the first nested case-control study to demonstrate a significant association between the polymorphisms of genes in the NHEJ pathway and lung cancer susceptibility and prognosis. The results may be useful for risk assessment and disease monitoring of patients with NSCLC.

FAMILIAL RISK FOR LUNG CANCER BY HISTOLOGY AND AGE OF ONSET: EVIDENCE FOR RECESSIVE INHERITANCE

The authors used the Swedish Family-Cancer Database to search for evidence for a genetic predisposition in lung cancer. Familial risks in offspring were increased for all lung cancer to 1.77 when a parent was affected with any lung cancers; the comparable risk among siblings was 2.15. At young age, risks between siblings were higher than those between offspring and parents for all histological types of lung cancer. The present data suggest that 1.7% of lung cancers up to age 68 years are heritable and probably due to a high-penetrant recessive gene or genes that predispose to tobacco carcinogens.

Association between X-ray repair cross complementing group 1 codon 399 and 194 polymorphisms and lung cancer risk: a meta-analysis

Genetic variations in DNA repair genes are thought to modify DNA repair capacity and suggested to be related to cancer risk. However, epidemiological results have been inconsistent. In this meta-analysis, we assessed reported studies of association between polymorphisms of X-ray repair cross complementing group 1 (XRCC1) codon 399 and 194, and lung cancer risk. We found decreased lung cancer risk among subjects carrying XRCC1 codon 194 Arg/Trp genotype [odds ratio (OR)=0.88, 95% confidence interval (95% CI): 0.79-0.97], using 4848 cases and 6592 controls from 16 studies. There was no association between lung cancer risk and XRCC1 codon 399 polymorphism in total population, when stratified by source of control, we found a protective effect of the XRCC1 codon 399 Gln/Gln and Arg/Gln or Gln/Gln polymorphisms for lung cancer on the basis of population control (OR=0.73, 95% CI: 0.58-0.92; OR=0.86, 95% CI: 0.77-0.97, respectively). Data indicated that certain XRCC1 codon 399 and 194 variant may affect the susceptibility of lung cancer. Recommendations for further studies include pooling of individual data to facilitate evaluation of multigenic effects and detailed analysis of effect modification by environmental exposure.

Lung cancer susceptibility model based on age, family history and genetic variants

Background

Epidemiological and pedigree studies suggest that lung cancer results from the combined effects of age, smoking, impaired lung function and genetic factors. In a case control association study of healthy smokers and lung cancer cases, we identified genetic markers associated with either susceptibility or protection to lung cancer.

Methodology/Principal Findings

We screened 157 candidate single nucleotide polymorphisms (SNP) in a discovery cohort of 439 subjects (200 controls and 239 lung cancer cases) and identified 30 SNPs associated with either the healthy smokers (protective) or lung cancer (susceptibility) phenotype. After genotyping this 30 SNP panel in a validation cohort of 491 subjects (248 controls and 207 lung cancers) and, using the same protective and susceptibility genotypes from our discovery cohort, a 20 SNP panel was selected based on replication of SNP associations in the validation cohort. Following multivariate logistic regression analyses, including the selected SNPs from runs 1 and 2, we found age and family history of lung cancer to be significantly and independently associated with lung cancer. Numeric scores were assigned to both the SNP and demographic data, and combined to form a simple algorithm of risk.

Conclusions/Significance

Significant differences in the distribution of the lung cancer susceptibility score was found between normal controls and lung cancer cases, which remained after accounting for differences in lung function. Validation in other case-control and prospective cohorts are underway to further define the potential clinical utility of this model.

The positive correlation between gene expression of the two angiogenic factors: VEGF and BMP-2 in lung cancer patients

Lung cancer is a particular challenge in oncology. More than 1 million new cases occur worldwide every year and despite many clinical trials and modern diagnostic techniques, long-term survival rate has only marginally improved. The aim of the current research is to explore new molecular prognostic factors and identify new targets for anticancer therapy. Current evidence shows that angiogenesis is controlled by several angiogenic factors including VEGF and BMP-2. It has been also demonstrated that VEGF plays a key role in this process that is essential in carcinogenesis. Our study has shown that the expressions of the VEGF, BMP-2 and BMP-4 mRNAs were significantly higher (7.1-fold, 25.6-fold and 2.3-fold, respectively) in lung cancer samples than in adjacent normal lung tissues (real-time RT-PCR). Analysis based on the Pearson's correlation coefficient indicated the positive correlation between VEGF and BMP-2 gene expression, whereas no significant correlation between VEGF and BMP-4 gene expression was found. The mean+/-standard deviation serum level of VEGF was 423+/-136 pg/ml. Significant differences in the serum levels of VEGF between patients with T1 tumors and patients with T2, T3 or T4 tumors were observed. Patients with T2, T3 and T4 tumors, respectively, had 1.6-fold, 1.8-fold and 2.3-fold greater serum levels of VEGF than their peers with T1 tumors. In current study patients homozygous for the 936T allele of the +936C/T VEGF gene polymorphism had 12-fold lower VEGF gene expression and 1.3-fold lower VEGF serum level than patients homozygous for the 936C allele. In conclusion, our findings underline the importance of the two angiogenic factors namely VEGF and BMP-2 as well as +936C/T VEGF gene polymorphism in the evaluation of lung cancer patients.

A polymorphism in the APE1 gene promoter is associated with lung cancer risk

Apurinic/apyrimidinic endonuclease 1 (APE1) is an essential enzyme in the base excision repair pathway, which is the primary mechanism for the repair of DNA damage caused by oxidation and alkylation. We hypothesized that polymorphisms of APE1 are associated with risk for lung cancer. In the hospital-based matched case-control study, a total of 730 lung cancer cases and 730 cancer-free controls were genotyped for four APE1 haplotype-tagging polymorphisms (that is, -656T>G, 400A>G, 630T>C, and 1350T>G). Among them, the single-nucleotide polymorphism -656T>G located in the promoter region of APE1 was significantly associated with risk for lung cancer. We found that, compared with -656 TT homozygotes, the variant genotypes were associated with a significantly decreased risk [adjusted odds ratio, 0.51; 95% confidence interval (95% CI), 0.33-0.79 for -656 TG; adjusted odds ratio, 0.43; 95% CI, 0.25-0.76 for -656 GG, respectively]. Furthermore, we found a statistically significant reduced risk of -656T>G variants among heavy smokers (adjusted odds ratio, 0.52; 95% CI, 0.30-0.93 for -656 TG; adjusted odds ratio, 0.27; 95% CI, 0.13-0.57 for -656 GG, respectively), with a significant gene-smoking interaction (P = 0.013). A similar gene-smoking interaction in the context of APE1 haplotypes was also observed. The in vitro promoter assay revealed that the -656 G allele had a significantly higher transcriptional activity than that of the -656 T allele. Together, our results suggest that polymorphisms of the APE1 gene possibly interact with smoking and may contribute to the development of lung cancer.

[Effects of Feiyanning formula on expressions of mRNAs and proteins of CXCL12 and CXCR4 in mice with Lewis tumors]

OBJECTIVE

To observe the effects of Feiyanning (FYN) formula, a compound traditional Chinese herbal medicine, on the expressions of CXCL12 and CXC chemokine receptor 4 (CXCR4) mRNAs and proteins in Lewis tumors in C57 mice.

METHODS

A total of 24 C57BL-6 mice were used in this study. Lewis cells were subcutaneously injected to the right armpit to establish the tumor-bearing model. The C57 mice bearing Lewis tumor were randomly divided into untreated group, chemotherapy group, FYN group and chemotherapy plus FYN group. Reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry were employed to measure the expressions of CXCL12 and CXCR4 mRNAs and proteins in Lewis tumors in C57 mice respectively.

RESULTS

The rates of lung cancer metastasis in the FYN group and the chemotherapy plus FYN group were markedly lower than that in the untreated group or the chemotherapy group. The expressions of CXCL12 and CXCR4 mRNAs and proteins appeared in tumor tissue in the untreated group. Although there was no significant difference in the expressions of mRNA and protein of CXCL12 among all groups (P>0.05), the expressions of mRNA and protein of CXCR4 in the untreated group and the chemotherapy group were markedly lower than those in the FYN group and the chemotherapy plus FYN group (P<0.05).

CONCLUSION

FYN can inhibit the metastasis of Lewis tumor loaded in C57 mice. Its mechanisms may be related to its down-regulation of the expression of chemokine receptor CXCR4, and affecting the role of CXCL12-CXCR4 biological axis.

Role of host interleukin 1beta gene (IL-1B) and interleukin 1 receptor antagonist gene (IL-1RN) polymorphisms in clinical outcomes in Helicobacter pylori-positive Turkish patients with dyspepsia

BACKGROUND

Helicobacter pylori infection leads to different clinical outcomes depending on both host and bacterial factors. In a recent study, we identified H. pylori cagE and babA2 genotypes as independent predictors of duodenal ulcer (DU) and gastric cancer (GC) in dyspepsia patients, but no previous studies have examined the role of host-related genetic factors in Turkey. This time our aim was to evaluate whether polymorphisms of the interleukin 1B (IL-1B) and the interleukin 1 receptor antagonist (IL-1RN) genes are important factors in the differential expression of gastroduodenal diseases in H. pylori-positive dyspepsia patients.

METHODS

Ninety-three H. pylori-positive patients, 30 with nonulcer dyspepsia (NUD), 30 with DU, and 33 with GC, were investigated. The IL-1B-511 and IL-1B-31 biallelic polymorphisms, and the IL-1RN intron 2 variable number tandem repeat were genotyped by polymerase chain reaction and single-strand confirmation polymorphism analysis.

RESULTS

The IL-1RN-1/1 genotype was significantly more prevalent among patients with NUD than among those with GC (chi(2) = 9.270; P = 0.002), and the IL-1RN-1/2 genotype was significantly more common in patients with GC (chi(2) = 6.01; P = 0.014). Multivariate regression analysis showed that cagE, babA2, and IL-1RN-1/2 genotypes were independent predictors of GC, but when patients with benign disorders were grouped together (NUD + DU) and compared with patients with GC, regression analysis disclosed that babA2 (P = 0.000) and IL-1B-31 gene polymorphisms (CC or CT) (P = 0.01) were the only independent markers of GC.

CONCLUSIONS

When analyzed together with host genetic factors, the well established bacterial risk factor babA2 seems to be the most important predictor of malignant disorders, and the presence of the IL-1B-31TT genotype emerges as a protective factor against them.