Genetics of lung-cancer susceptibility

Methylenetetrahydrofolate reductase 677TT genotype may be associated with an increased lung cancer risk in North China: an updated meta-analysis

Background

Although many epidemiology studies have investigated the methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms and their associations with lung cancer (LC), definite conclusions cannot be drawn. To clarify the effects of MTHFR polymorphisms on the risk of LC, we performed a meta-analysis in Chinese populations.

Material/Methods

Related studies were identified from PubMed, Springer Link, Ovid, Chinese Wanfang Data Knowledge Service Platform, Chinese National Knowledge Infrastructure (CNKI), and Chinese Biology Medicine (CBM) until 16 February 2014. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the strength of the associations.

Results

A total of 11 studies with 2487 LC cases and 3228 controls were included in this meta-analysis. Overall, no significant association was found between MTHFR C677T polymorphism and LC risk when all studies in Chinese populations were pooled into this meta-analysis. In subgroup analyses stratified by geographical location and source of controls, significantly increased risk was found in North China (T vs. C: OR=1.28, 95% CI: 1.14–1.44; TT vs. CC: OR=1.67, 95% CI: 1.33–2.10; TT + CT vs. CC, OR=1.39, 95% CI=1.15–1.69; TT vs. CC + CT: OR=1.46, 95% CI: 1.03–2.06) and in population-based studies (TT vs. CC: OR=1.37, 95% CI: 1.14–1.65; TT vs. CC + CT: OR=1.25, 95% CI: 1.07–1.45).

Conclusions

This meta-analysis provides evidence that MTHFR C677T polymorphism may contribute to LC development in North China. Studies with larger sample sizes and wider spectrum of populations are warranted to verify this finding.

A Genetic Lung Cancer Susceptibility Test may have a Positive Effect on Smoking Cessation

Smoking increases the risk of developing lung cancer. Genetic loci have been identified which could form the basis of a lung cancer susceptibility test; but little is known whether such a test would interest or motivate those trying to quit smoking. To address this, we investigated the attitudes of people trying to quit smoking towards genetic susceptibility testing for lung cancer. Participant's attitudes to topics associated with lung cancer susceptibility testing were assessed; were they interested in genetic testing? What impact would a hypothetical high- or low- risk result have on smoking cessation? 680 self-completion questionnaires were given to individuals attending National Health Service stop smoking clinics in three different areas of the United Kingdom between 2011 and 2012. 139 questionnaires were returned, giving a 20 % response rate. Participants expressed an interest in a genetic susceptibility test for lung cancer and almost all reported that a high-risk result would increase their motivation to stop smoking. However, many participants had a neutral attitude towards a low-risk result. Most participants agreed their smoking habit could lead to lung cancer. Lung cancer susceptibility testing may be a useful incentive to help people quit smoking. This study suggests the need for genetic services to work with smoking cessation teams if routine testing becomes available in the future.

Angiotensin-converting enzyme insertion/deletion gene polymorphism and lung cancer risk: A meta-analysis

OBJECTIVE

Angiotensin-converting enzyme (ACE) I/D polymorphism has been reported to be associated with lung cancer, but the results of previous studies are conflicting. The present study was designed to investigate the association between this polymorphism and the risk of lung cancer using a meta-analysis of the published studies.

METHODS

Two investigators independently searched the PubMed, Embase and CNKI databases. This meta-analysis covered six case-control studies, including 807 lung cancer patients and 816 healthy controls.

RESULTS

The results of this meta-analysis based on all the studies showed no significant association between ACE I/D gene polymorphism and lung cancer risk (DD vs II: OR = 1.18, 95% CI = 0.68-2.04; DI vs II: OR = 0.93, 95% CI = 0.56-1.53; DD+DI vs II: OR = 1.01, 95% CI = 0.68-1.50; DD vs II+DD: OR =1.11, 95% CI = 0.73-1.71). In the subgroup analysis by race and the larger studies (n > 200 participants), no significant associations between the ACE I/D polymorphism and risk of lung cancer were indicated. However, when the analyses were restricted to small studies (n ≤ 200 participants), a significantly higher risk was observed (DD vs II: OR = 2.57, 95% CI = 1.24-5.30).

CONCLUSIONS

This meta-analysis suggests that the ACE gene I/D polymorphism may not be associated with the risk of lung cancer, and the observed increase in the risk of lung cancer may be due to small-study bias.

HPV and lung cancer risk: a meta-analysis

The potential causal association between human papillomavirus (HPV) and lung cancer (LC) remains controversial. We performed this meta-analysis to evaluate whether HPV infection in lung tissue is associated with LC compared with non-cancer controls. We also quantified this association in different LC subtypes. MEDLINE, EMBASE and Web of Science were searched through March 2014, using the search terms "lung cancer", "human papillomavirus", "HPV" and their combinations. Association was tested using odds ratio (OR) with 95% confidence intervals (95% CI). Heterogeneity was assessed using Q and I(2) statistic. Finally, nine studies, for a total of 1094 LCs and 484 non-cancer controls, were identified as eligible publications. The pooled results showed that HPV infection was associated with LC (OR=5.67, 95% CI: 3.09-10.40, P<0.001). Similar results were also observed in HPV16 and/or HPV18 (HPV16/18) infection analyses (OR=6.02, 95% CI: 3.22-11.28, P<0.001). HPV16/18 was significantly associated with lung squamous cell carcinoma (SCC) (OR=9.78, 95% CI: 6.28-15.22, P<0.001), while the pooled OR was 3.69 in lung adenocarcinoma (95% CI: 0.99-13.71, P=0.052). Our results suggest that lung tissue with HPV infection has a strong association with LC, and especially, HPV16/18 infection significantly increases SCC risk, which indicates a potential pathogenesis link between HPV and LC.

Role of nicotine dependence on the relationship between variants in the nicotinic receptor genes and risk of lung adenocarcinoma

Several variations in the nicotinic receptor genes have been identified to be associated with both lung cancer risk and smoking in the genome-wide association (GWA) studies. However, the relationships among these three factors (genetic variants, nicotine dependence, and lung cancer) remain unclear. In an attempt to elucidate these relationships, we applied mediation analysis to quantify the impact of nicotine dependence on the association between the nicotinic receptor genetic variants and lung adenocarcinoma risk. We evaluated 23 single nucleotide polymorphisms (SNPs) in the five nicotinic receptor related genes (CHRNB3, CHRNA6, and CHRNA5/A3/B4) previously reported to be associated with lung cancer risk and smoking behavior and 14 SNPs in the four 'control' genes (TERT, CLPTM1L, CYP1A1, and TP53), which were not reported in the smoking GWA studies. A total of 661 lung adenocarcinoma cases and 1,347 controls with a smoking history, obtained from the Environment and Genetics in Lung Cancer Etiology case-control study, were included in the study. Results show that nicotine dependence is a mediator of the association between lung adenocarcinoma and gene variations in the regions of CHRNA5/A3/B4 and accounts for approximately 15% of this relationship. The top two CHRNA3 SNPs associated with the risk for lung adenocarcinoma were rs1051730 and rs12914385 (p-value = 1.9×10(-10) and 1.1×10(-10), respectively). Also, these two SNPs had significant indirect effects on lung adenocarcinoma risk through nicotine dependence (p = 0.003 and 0.007). Gene variations rs2736100 and rs2853676 in TERT and rs401681 and rs31489 in CLPTM1L had significant direct associations on lung adenocarcinoma without indirect effects through nicotine dependence. Our findings suggest that nicotine dependence plays an important role between genetic variants in the CHRNA5/A3/B4 region, especially CHRNA3, and lung adenocarcinoma. This may provide valuable information for understanding the pathogenesis of lung adenocarcinoma and for conducting personalized smoking cessation interventions.

Epidermal growth factor receptor (EGFR) mutations in lung cancer: preclinical and clinical data

Lung cancer leads cancer-related mortality worldwide. Non-small-cell lung cancer (NSCLC), the most prevalent subtype of this recalcitrant cancer, is usually diagnosed at advanced stages, and available systemic therapies are mostly palliative. The probing of the NSCLC kinome has identified numerous nonoverlapping driver genomic events, including epidermal growth factor receptor (EGFR) gene mutations. This review provides a synopsis of preclinical and clinical data on EGFR mutated NSCLC and EGFR tyrosine kinase inhibitors (TKIs). Classic somatic EGFR kinase domain mutations (such as L858R and exon 19 deletions) make tumors addicted to their signaling cascades and generate a therapeutic window for the use of ATP-mimetic EGFR TKIs. The latter inhibit these kinases and their downstream effectors, and induce apoptosis in preclinical models. The aforementioned EGFR mutations are stout predictors of response and augmentation of progression-free survival when gefitinib, erlotinib, and afatinib are used for patients with advanced NSCLC. The benefits associated with these EGFR TKIs are limited by the mechanisms of tumor resistance, such as the gatekeeper EGFR-T790M mutation, and bypass activation of signaling cascades. Ongoing preclinical efforts for treating resistance have started to translate into patient care (including clinical trials of the covalent EGFR-T790M TKIs AZD9291 and CO-1686) and hold promise to further boost the median survival of patients with EGFR mutated NSCLC.

Identification of featured biomarkers in different types of lung cancer with DNA microarray

Lung cancer is a worldwide leading cause of cancer-related death. The aim of this study was to identify target genes and specific biomarkers for identification and treatment of different types of lung cancer with DNA microarray. Gene expression profile GSE6044 and miRNA microarray profile GSE17681 were downloaded from Gene Expression Omnibus database. The differentially expressed genes (DEGs) and miRNAs were screened with multtest package in R language. Then, functional enrichment analysis of identified DEGs was performed. Furthermore, the verified target genes based on screened miRNAs were selected from miRTarBase and miRecords databases. Then miRNA-target gene regulation network was constructed. APOE, CDC6 and ATP2B1were involved in most of the functions obtained for adenocarcinomas, small cell lung cancer and squamous cell carcinomas, respectively. The target DEGs of differentially expressed hsa-miR-29a included FGG in adenocarcinoma, RAN and COL4A1 in small cell lung cancer, GLUL in squamous cell carcinoma. The target DEGs of has-miR-7 were SNCA and SLC7A5 in adenocarcinoma and small cell lung cancer, respectively. ICAM1 and KIT were the target DEGs of hsa-miR-222 in adenocarcinoma and squamous cell carcinoma. The miRNAs and their differentially expressed target genes have the potential to be used in clinic for diagnosis and treatment of different kinds of lung cancer in the future.

Genetic susceptibility to lung cancer and co-morbidities

Lung cancer is a leading cause of cancer death and disease burden in many countries. Understanding of the biological pathways involved in lung cancer aetiology is required to identify key biomolecules that could be of significant clinical value, either as predictive, prognostic or diagnostic markers, or as targets for the development of novel therapies to treat this disease, in addition to smoking avoidance strategies. Genome-wide association studies (GWAS) have enabled significant progress in the past 5 years in investigating genetic susceptibility to lung cancer. Large scale, multi-cohort GWAS of mainly Caucasian, smoking, populations have identified strong associations for lung cancer mapped to chromosomal regions 15q [nicotinic acetylcholine receptor (nAChR) subunits: CHRNA3, CHRNA5], 5p (TERT-CLPTM1L locus) and 6p (BAT3-MSH5). Some studies in Asian populations of smokers have found similar risk loci, whereas GWAS in never smoking Asian females have identified associations in other chromosomal regions, e.g., 3q (TP63), that are distinct from smoking-related lung cancer risk loci. GWAS of smoking behaviour have identified risk loci for smoking quantity at 15q (similar genes to lung cancer susceptibility: CHRNA3, CHRNA5) and 19q (CYP2A6). Other genes have been mapped for smoking initiation and smoking cessation. In chronic obstructive pulmonary disease (COPD), which is a known risk factor for lung cancer, GWAS in large cohorts have also found CHRNA3 and CHRNA5 single nucleotide polymorphisms (SNPs) mapping at 15q as risk loci, as well as other regions at 4q31 (HHIP), 4q24 (FAM13A) and 5q (HTR4). The overlap in risk loci between lung cancer, smoking behaviour and COPD may be due to the effects of nicotine addiction; however, more work needs to be undertaken to explore the potential direct effects of nicotine and its metabolites in gene-environment interaction in these phenotypes. Goals of future genetic susceptibility studies of lung cancer should focus on refining the strongest risk loci in a wide range of populations with lung cancer, and integrating other clinical and biomarker information, in order to achieve the aim of personalised therapy for lung cancer.

Opium use: an emerging risk factor for cancer?

An estimated 16·5 million people worldwide illicitly use opiates, of whom 4 million use raw opium. We did a systematic review to investigate the association between opium use and cancer incidence and mortality. Opium use was associated with an increased risk of cancers of the oesophagus, stomach, larynx, lung, and urinary bladder. Although the present evidence suggests that these associations are possibly causal, further epidemiological studies (particularly prospective studies that collect detailed data about lifetime opium use and control for a broad range of potential confounders) are needed.

[Survey and analysis of awareness of lung cancer prevention and control in a LDCT lung cancer screening project in Tianjin Dagang Oilfield of China]

BACKGROUND AND OBJECTIVE

It has been proven that increase of the awareness level of lung cancer prevention and control could enhance participation of lung cancer screening of lung cancer high risk group. The aim of this study is to investigate the awareness level of lung cancer prevention and control and the effect of individual characteristics on lung cancer awareness, and to provide evidence for comprehensive lung cancer prevention in high risk areas of lung cancer.

METHODS

Staffs of Tianjin Dagang Oil Field who participate low dose CT (LDCT) lung cancer screening by cluster sampling or according to voluntary principle were surveyed, data of lung cancer awareness were collected by questionnaire.

RESULTS

A total of 1,633 valid questionnaires were collected. The average age of respondents was 60.08±6.58. Most participants were males (82.2%) while female only accounted for 17.8%. The proportions of awareness about lung cancer in China, risk factors, screening methods and the knowledge of health examination were 64.5%, 77.1%, 43.7%, 49.6% respectively. Result of multiple logistic regression analysis showed that education level, smoking (pack-year), age, prior tuberculosis were the influencing factors of lung cancer awareness with adjusted Ors for education and age level as of 0.567 (95%CI: 0.439-0.733) and 1.373 (95%CI: 1.084-1.739) respectively. 80.3% of the participants can accept health examination once a year, while the ability to pay the medical expenses was not high. The influencing factors of health examination willingness were gender, age, income, the knowledge of lung cancer.

CONCLUSIONS

Education level and smoking affect the awareness of lung cancer prevention and control, health education for lung cancer should be conducted especially in population with low education level. Comprehensive lung cancer control in high risk areas should combined lung cancer screening, tobacco control and health education.

Replication of results of a genome-wide association study on lung cancer survival in a Korean population

Recently, a genome-wide association study (GWAS) identified single nucleotide polymorphisms (SNPs) that may influence the prognosis of early-stage non-small cell lung cancer (NSCLC) in Caucasians. We attempted to replicate the impact of genetic variants identified in the GWAS on lung cancer survival in a Korean population. A total of 363 patients with surgically resected NSCLCs were enrolled, and 12 SNPs were genotyped using the SEQUENOM MassARRAY iPLEX assay, TaqMan assay, or a polymerase chain reaction-restriction fragment length polymorphism analysis. The association between genotypes and overall survival (OS) was analyzed. Among the 12 SNPs, the rs6034368T>C was associated with OS. Patients with the rs6034368C allele showed a better OS than the patients with the rs6034368T allele (adjusted hazard ratio = 0.72, confidence interval = 0.56-0.93, P = 0.01). The rs12446308A>G had an effect on OS, but it was marginally significant (under a codominant model, adjusted hazard ratio = 1.85, confidence interval = 0.98-3.47, P = 0.06). We identified that the rs6034368T>C was associated with survival in early-stage NSCLC in a Korean population.

The molecular era of surfactant biology

Advances in the physiology, biochemistry, molecular and cell biology of the pulmonary surfactant system transformed the clinical care and outcome of preterm infants with respiratory distress syndrome. The molecular era of surfactant biology provided genetic insights into the pathogenesis of pulmonary disorders, previously termed 'idiopathic', that affect newborn infants, children and adults. Knowledge related to the structure and function of the surfactant proteins and their roles in alveolar homeostasis has provided new diagnostic, prognostic and therapeutic tools to advance our understanding of the causes and treatments of acute and chronic lung diseases. Severe lung disease in newborn infants and older patients is caused by mutations in genes regulating alveolar epithelial cells and surfactant homeostasis. Mutations in genes encoding the surfactant proteins, transcription factors critical for alveolar morphogenesis and surfactant clearance, are now known to play important roles in the pathogenesis of chronic lung diseases. Identification of the genes underlying the diseases of alveolar homeostasis is useful for the diagnosis of lung disease before and after birth.

Occupational pesticide exposures and respiratory health

Pesticides have been widely used to control pest and pest-related diseases in agriculture, fishery, forestry and the food industry. In this review, we identify a number of respiratory symptoms and diseases that have been associated with occupational pesticide exposures. Impaired lung function has also been observed among people occupationally exposed to pesticides. There was strong evidence for an association between occupational pesticide exposure and asthma, especially in agricultural occupations. In addition, we found suggestive evidence for a link between occupational pesticide exposure and chronic bronchitis or COPD. There was inconclusive evidence for the association between occupational pesticide exposure and lung cancer. Better control of pesticide uses and enforcement of safety behaviors, such as using personal protection equipment (PPE) in the workplace, are critical for reducing the risk of developing pesticide-related symptoms and diseases. Educational training programs focusing on basic safety precautions and proper uses of personal protection equipment (PPE) are possible interventions that could be used to control the respiratory diseases associated with pesticide exposure in occupational setting.

NBN Gene Polymorphisms and Cancer Susceptibility: A Systemic Review

The relationship between DNA repair failure and cancer is well established as in the case of rare, high penetrant genes in high cancer risk families. Beside this, in the last two decades, several studies have investigated a possible association between low penetrant polymorphic variants in genes devoted to DNA repair pathways and risk for developing cancer. This relationship would be also supported by the observation that DNA repair processes may be modulated by sequence variants in DNA repair genes, leading to susceptibility to environmental carcinogens. In this framework, the aim of this review is to provide the reader with the state of the art on the association between common genetic variants and cancer risk, limiting the attention to single nucleotide polymorphisms (SNPs) of the NBN gene and providing the various odd ratios (ORs). In this respect, the NBN protein, together with MRE11 and RAD50, is part of the MRN complex which is a central player in the very early steps of sensing and processing of DNA double-strand breaks (DSBs), in telomere maintenance, in cell cycle control, and in genomic integrity in general. So far, many papers were devoted to ascertain possible association between common synonymous and non-synonymous NBN gene polymorphisms and increased cancer risk. However, the results still remain inconsistent and inconclusive also in meta-analysis studies for the most investigated E185Q NBN miscoding variant.

The SNP rs402710 in 5p15.33 is associated with lung cancer risk: a replication study in Chinese population and a meta-analysis

Background

Lung cancer is the most commonly diagnosed cancer and leading cause of cancer mortality in the world. A single nucleotide polymorphism (SNP), rs402710, located in 5p15.33, was firstly identified to be associated with the lung cancer risk in a genome-wide association study. However, some following replication studies yielded inconsistent results.

Methodology and Findings

A case-control study of 611 cases and 1062 controls in a Chinese population was conducted, and then a meta-analysis integrating the current and previously published studies with a total 31811 cases and 36333 controls was performed to explore the real effect of rs402710 on lung cancer susceptibility. Significant associations between the SNP rs402710 and lung cancer risk were observed in both case-control study and meta-analysis, with ORs equal to 0.77 (95%CI = 0.63–0.95) and 0.83 (95%CI = 0.81–0.86) in dominant model, respectively. By stratified analysis of our case-control study, the associations were also observed in never smoker group and non-small cell lung cancer(NSCLC) group with ORs equal to 0.71 (95%CI = 0.53–0.95) and 0.69 (95%CI = 0.55–0.87), which was remarkable that larger effect of the minor allele T was seen in the two groups than that in overall lung cancer. Besides, the sensitive and cumulative analysis indicated the robust stability of the current results of meta-analysis.

Conclusion

The results from our replication study and the meta-analysis provided firm evidence that rs402710 T allele significantly contributed to decreased lung cancer risk, and the case-control study implied that the variant may yield stronger effect on NSCLC and never smokers. However, the mechanism underlying the polymorphism conferring susceptibility to lung cancer is warranted to clarify in the follow-up studies.

Where genotype is not predictive of phenotype: towards an understanding of the molecular basis of reduced penetrance in human inherited disease

Some individuals with a particular disease-causing mutation or genotype fail to express most if not all features of the disease in question, a phenomenon that is known as 'reduced (or incomplete) penetrance'. Reduced penetrance is not uncommon; indeed, there are many known examples of 'disease-causing mutations' that fail to cause disease in at least a proportion of the individuals who carry them. Reduced penetrance may therefore explain not only why genetic diseases are occasionally transmitted through unaffected parents, but also why healthy individuals can harbour quite large numbers of potentially disadvantageous variants in their genomes without suffering any obvious ill effects. Reduced penetrance can be a function of the specific mutation(s) involved or of allele dosage. It may also result from differential allelic expression, copy number variation or the modulating influence of additional genetic variants in cis or in trans. The penetrance of some pathogenic genotypes is known to be age- and/or sex-dependent. Variable penetrance may also reflect the action of unlinked modifier genes, epigenetic changes or environmental factors. At least in some cases, complete penetrance appears to require the presence of one or more genetic variants at other loci. In this review, we summarize the evidence for reduced penetrance being a widespread phenomenon in human genetics and explore some of the molecular mechanisms that may help to explain this enigmatic characteristic of human inherited disease.

CHRNA5-A3-B4 genetic variants alter nicotine intake and interact with tobacco use to influence body weight in Alaska Native tobacco users

BACKGROUND AND AIMS

Gene variants in CHRNA5-A3-B4, which encode for the α5, α3 and β4 nicotinic receptor subunits, are associated with altered smoking behaviors in European Americans. Little is known about CHRNA5-A3-B4 and its association with smoking behaviors and weight in Alaska Native people, which is a population with high prevalence but low levels of tobacco consumption, extensive smokeless tobacco use and high rates of obesity. We investigated CHRNA5-A3-B4 haplotype structure and its association with nicotine intake and obesity in Alaska Native people.

DESIGN, SETTING AND PARTICIPANTS

A cross-sectional study of 400 Alaska Native individuals, including 290 tobacco users.

MEASUREMENTS

CHRNA5-A3-B4 genotype, body weight and tobacco consumption biomarkers such as plasma cotinine and urinary total nicotine equivalents (TNE).

FINDINGS

Alaska Native people have a distinct CHRNA5-A3-B4 haplotype structure compared with European/African Americans. In 290 Alaska Native tobacco users the 'G' allele of rs578776, which tagged a 30 kb haplotype in CHRNA5-A3-B4, was prevalent (16%) and associated significantly with nicotine intake (20% higher plasma cotinine, P < 0.001, 16% higher TNE, P = 0.076), while rs16969968 was not associated with nicotine intake. Rs578776 acted in combination with CYP2A6, the main nicotine-metabolizing enzyme, to increase nicotine intake by 1.8-fold compared with the low-risk group (P < 0.001). Furthermore, rs2869950, a single nucleotide polymorphism 5' to CHRNB4, was associated significantly with increased body mass index (P < 0.01) in the tobacco users even after controlling for differences in nicotine intake (P < 0.01).

CONCLUSIONS

Genetic variants in CHRNA5-A3-B4 alter nicotine intake and body mass index in a population of Alaska Native people, who have a distinct haplotype structure, smoking behaviors and prevalence of obesity.

Association between SOD2 C47T polymorphism and lung cancer susceptibility: a meta-analysis

Lung cancer is one of the most common cancers worldwide, but its etiology is still unclear. Superoxide dismutase 2 (SOD2) plays an essential role in oxidative stress and may be involved in the development of lung cancer. The association between SOD2 C47T polymorphism and lung cancer risk has been widely investigated, but the results of previous studies are contradictory. We conducted a meta-analysis to comprehensively assess the association between SOD2 C47T polymorphism and lung cancer. The association was estimated by odds ratio (OR) with 95 % confidence interval (95 % CI). A total of 10 studies with 5,146 cases and 6,173 controls were identified. The results showed that SOD2 C47T polymorphism was significantly associated with lung cancer (T versus C: OR = 0.88, 95 % CI = 0.83-0.93, P < 0.001; TT versus CC: OR = 0.74, 95 % CI = 0.66-0.83, P < 0.001; TT versus

CC/CT

OR = 0.81, 95 % CI = 0.73-0.89, P < 0.001). Subgroup analysis by ethnicity suggested that SOD2 C47T polymorphism was significantly associated with lung cancer in both East Asians and Caucasians. Conclusively, this meta-analysis strongly suggests that SOD2 C47T polymorphism is significantly associated with lung cancer.

Association between MPO 463G>A polymorphism and risk of lung cancer: a meta-analysis

There is a possible association between myeloperoxidase (MPO) 463G>A polymorphism and risk of lung cancer, but previous studies report conflicting results. We performed a meta-analysis of available molecular epidemiologic studies to comprehensively assess the association between MPO 463G>A polymorphism and risk of lung cancer. A systemic literature search was performed in Pubmed, Embase, and Wanfang databases for molecular epidemiologic studies on the association MPO 463G>A polymorphism and risk of lung cancer on March 16, 2013. The pooled odds ratios (ORs) with their 95% confidence interval (95% CI) were calculated to assess the strength of the association. Twenty-six individual case-control studies with a total of 18,433 subjects (7,752 cases and 10,681 controls) were finally included into the meta-analysis. Overall, MPO 463G>A polymorphism was significantly associated with decreased risk of lung cancer under two main genetic comparison models (for A versus G, OR = 0.91, 95 % CI 0.83-0.99, P = 0.035; for AG/AA versus GG, OR = 0.90, 95% CI 0.81-0.99, P = 0.029). Meta-analysis of studies with high quality also showed that MPO 463G>A polymorphism was significantly associated with decreased risk of lung cancer under two main genetic comparison models (for A versus G, OR = 0.91, 95% CI 0.83-0.99, P = 0.035; for AG/AA versus GG, OR = 0.90, 95% CI 0.80-0.99, P = 0.048). Subgroup analysis by ethnicity further showed that there was a significant association between MPO 463G>A polymorphism and decreased risk of lung cancer in Caucasians but not in Asians. The meta-analysis suggests that MPO 463G>A polymorphism is associated with decreased risk of lung cancer, especially in Caucasians.

Myeloperoxidase G463A polymorphism and lung cancer risk in Asians: a pooled analysis

Myeloperoxidase (MPO) is an endogenous oxidant enzyme and can generate reactive oxygen species. The MPO G463A polymorphism influences MPO transcription levels and has been proposed to be associated with risk of lung cancer. To assess the effect of MPO G463A polymorphism on lung cancer risk in Asians, a pooled analysis of published case-control studies was performed. PubMed, Embase, China Biomedical Literature, and Wanfang Medicine databases were searched for eligible studies. The strength of the association between MPO G463A polymorphism and lung cancer risk was measured by odds ratio (OR) with 95 % confidence interval (95% CI). Finally, eight studies with a total of 1,679 lung cancer cases and 1,876 non-cancer controls were included. Overall, MPO G463A polymorphism was associated with decreased risk of lung cancer risk in Asians under two genetic models (OR AA vs. GG = 0.58, 95% CI 0.36-0.96, P = 0.033; OR AA vs. GG+AG = 0.60, 95% CI 0.37-0.98, P = 0.040). There was no obvious risk of publication bias in this meta-analysis. In conclusion, the pooled analysis suggests that MPO G463A polymorphism is associated with decreased risk of lung cancer risk in Asians.

Positron emission tomography-computed tomography in the management of lung cancer: An update

This communication presents an update on the current role of positron emission tomography-computed tomography (PET-CT) in the various clinical decision-making steps in lung carcinoma. The modality has been reported to be useful in characterizing solitary pulmonary nodules, improving lung cancer staging, especially for the detection of nodal and metastatic site involvement, guiding therapy, monitoring treatment response, and predicting outcome in non-small cell lung carcinoma (NSCLC). Its role has been more extensively evaluated in NSCLC than small cell lung carcinoma (SCLC). Limitations in FDG PET-CT are encountered in cases of tumor histotypes characterized by low glucose uptake (mucinous forms, bronchioalveolar carcinoma, neuroendocrine tumors), in the assessment of brain metastases (high physiologic 18F-FDG uptake in the brain) and in cases presenting with associated inflammation. The future potentials of newer PET tracers beyond FDG are enumerated. An evolving area is PET-guided assessment of targeted therapy (e.g., EGFR and EGFR tyrosine kinase overexpression) in tumors which have significant potential for drug development.

Association between XRCC1 Arg399Gln polymorphism and hepatitis virus-related hepatocellular carcinoma risk in Asian population

To investigate the association between X-ray repair cross-complementing group 1 (XRCC1) Arg399Gln polymorphism and hepatitis virus-related hepatocellular carcinoma risk, we performed a systematic meta-analysis of eligible case-control studies. Eligible studies were identified from the PubMed, Embase, and Chinese National Knowledge Infrastructure databases up to March 2013. The odds ratios (ORs) and corresponding 95 % confidence interval (95 % CI) of XRCC1 Arg399Gln polymorphism in hepatitis virus-related hepatocellular carcinoma cases compared with those in controls were calculated. The meta-analysis was performed using fixed-effect or random-effect methods according to the absence or presence of heterogeneity. This meta-analysis included 1,558 cases with hepatitis virus-related hepatocellular carcinoma and 1,338 controls. Meta-analysis of available data showed that there was no association between XRCC1 Arg399Gln polymorphism and risk of hepatitis virus-related hepatocellular carcinoma under all contrast models (Gln vs. Arg: fixed-effect OR = 0.92, 95 % CI 0.82-1.04, P = 0.18; GlnGln vs. ArgArg: random-effect OR = 0.79, 95 % CI 0.50-1.25, P = 0.32; GlnGln/ArgGln vs. ArgArg: fixed-effect OR = 0.92, 95 % CI 0.79-1.07, P = 0.28; and GlnGln vs. ArgArg/ArgGln: random-effect OR = 0.83, 95 % CI 0.52-1.34, P = 0.45). Sensitivity analysis further showed that there was no association between XRCC1 Arg399Gln polymorphism and risk of hepatitis B-related hepatocellular carcinoma under all contrast models (Gln vs. Arg: fixed-effect OR = 0.93, 95 % CI 0.82-1.05, P = 0.25; GlnGln vs. ArgArg: fixed-effect OR = 0.86, 95 % CI 0.64-1.16, P = 0.32; GlnGln/ArgGln vs. ArgArg: fixed-effect OR = 0.93, 95 % CI 0.80-1.10, P = 0.41; and GlnGln vs. ArgArg/ArgGln: fixed-effect OR = 0.85, 95 % CI 0.63-1.13, P = 0.26). Our meta-analysis of the available data did not find an obvious effect of XRCC1 Arg399Gln polymorphism on hepatitis-related hepatocellular carcinoma. More well-designed studies with large sample are needed to further verify the effect.

CHEK2*1100delC homozygosity in the Netherlands--prevalence and risk of breast and lung cancer

The 1100delC mutation in the CHEK2 gene has a carrier frequency of up to 1.5% in individuals from North-West Europe. Women heterozygous for 1100delC have an increased breast cancer risk (odds ratio 2.7). To explore the prevalence and clinical consequences of 1100delC homozygosity in the Netherlands, we genotyped a sporadic breast cancer hospital-based cohort, a group of non-BRCA1/2 breast cancer families, and breast tumors from a tumor tissue bank. Three 1100delC homozygous patients were found in the cohort of 1434 sporadic breast cancer patients, suggesting an increased breast cancer risk for 1100delC homozygotes (odds ratio 3.4, 95% confidence interval 0.4-32.6, P=0.3). Another 1100delC homozygote was found in 592 individuals from 108 non-BRCA1/2 breast cancer families, and two more were found after testing 1706 breast tumors and confirming homozygosity on their wild-type DNA. Follow-up data was available for five homozygous patients, and remarkably, three of them had developed contralateral breast cancer. A possible relationship between 1100delC and lung cancer risk was investigated in 457 unrelated lung cancer patients but could not be confirmed. Due to the small number of 1100delC homozygotes identified, the breast cancer risk estimate associated with this genotype had limited accuracy but is probably higher than the risk in heterozygous females. Screening for CHEK2 1100delC could be beneficial in countries with a relatively high allele frequency.

X-ray repair cross-complementing group 1 Arg194Trp polymorphism is associated with increased risk of lung cancer in Chinese Han population

There were many studies performed to assess the association between X-ray repair cross-complementing group 1 (XRCC1) Arg194Trp polymorphism and lung cancer risk in Chinese Han population, but contradictory results were reported. To provide a comprehensive and objective assessment of the association, a meta-analysis of all eligible case-control studies was carried out. After searching the databases and reading the abstracts, 12 case-control studies on the association between XRCC1 Arg194Trp polymorphism and lung cancer risk were finally included into this meta-analysis. Those 12 studies included a total of 4,385 cases and 4,545 controls. XRCC1 Arg194Trp polymorphism was associated with increased risk of lung cancer in Chinese Han population under three main models (allele contrast model, odds ratio (OR) = 1.12, 95 % confidence interval (CI) 1.00-1.26, P = 0.049; homozygote model, OR = 1.27, 95 % CI 1.09-1.48, P = 0.003; recessive model, OR = 1.26, 95 % CI 1.09-1.46, P = 0.003). However, there was no obvious association between XRCC1 Arg194Trp polymorphism and lung cancer risk under the dominant model (OR = 1.06, 95 % CI 0.98-1.16, P = 0.146). Sensitivity analysis suggested the stability and liability of this meta-analysis. Therefore, this meta-analysis suggests that XRCC1 Arg194Trp polymorphism is associated with increased risk of lung cancer in Chinese Han population.

Genome-wide analysis of runs of homozygosity identifies new susceptibility regions of lung cancer in Han Chinese

Runs of homozygosity (ROHs) are a class of important but poorly studied genomic variations and may be involved in individual susceptibility to diseases. To better understand ROH and its relationship with lung cancer, we performed a genome-wide ROH analysis of a subset of a previous genome-wide case-control study (1,473 cases and 1,962 controls) in a Han Chinese population. ROHs were classified into two classes, based on lengths, intermediate and long ROHs, to evaluate their association with lung cancer risk using existing genome-wide single nucleotide polymorphism (SNP) data. We found that the overall level of intermediate ROHs was significantly associated with a decreased risk of lung cancer (odds ratio = 0.63; 95% confidence interval: 0.51-0.77; P = 4.78×10⁻⁶ ), while the long ROHs seemed to be a risk factor of lung cancer. We also identified one ROH region at 14q23.1 that was consistently associated with lung cancer risk in the study. These results indicated that ROHs may be a new class of variation which may be associated with lung cancer risk, and genetic variants at 14q23.1 may be involved in the development of lung cancer.

miRNA regulated pathways in late stage murine lung development

Background

MicroRNAs play important roles in regulating biological processes, including organ morphogenesis and maturation. However, little is known about specific pathways regulated by miRNA during lung development. Between the canalicular and saccular stages of the developing lung several important cellular events occur, including the onset of surfactant synthesis, microvascular remodeling and structural preparation for subsequent alveolarization. The miRNAs that are actively regulated, and the identity of their targets during this important developmental interval in the lung remain elusive.

Results

Using TLDA low density real-time PCR arrays, the expression of 376 miRNAs in male and female fetal mouse lungs of gestational days E15 – E18 were profiled. Statistical analyses identified 25 and 37 miRNAs that changed significantly between sexes and with gestation, respectively. In silico analysis using Ingenuity Pathway Analysis (IPA) identified specific pathways and networks known to be targets of these miRNAs which are important to lung development. Pathways that are targeted by sex regulated miRNAs include retinoin, IGFR1, Tp53 and Akt. Pathways targeted by gestation-regulated miRNAs include VEGFA and mediators of glucose metabolism.

Conclusion

MiRNAs are differentially regulated across time and between sexes during the canalicular and saccular stages of lung development. Sex-associated differential miRNA expression may regulate the differences in structural and functional male and female lung development, as shown by networks generated using in silico analysis. These data provide a valuable resource to further enhance the understanding of miRNA control of lung development and maturation.

Association between the NBS1 Glu185Gln polymorphism and lung cancer risk: a systemic review and meta-analysis

Nijmegen Breakage Syndrome protein 1 (NBS1) is one of the most important DNA repair proteins playing important roles in maintaining the genomic stability of NDA. Previous studies regarding the association between NBS1 8360G>C (Glu185Gln) polymorphism and lung cancer reported conflicting results. To derive a more precise estimation of this association, a systemic review and meta-analysis was performed. We performed a meta-analysis using eligible case-control studies to summarize the data on the association between the NBS1 Glu185Gln polymorphism and lung cancer risk. Odds ratios (ORs) with corresponding 95 % confidence intervals (95 %CIs) were pooled to assess the association between NBS1 Glu185Gln polymorphism and lung cancer risk. Six case-control studies with a total of 2,348 lung cancer cases and 2,401 controls without canner were included into the meta-analysis. Overall, there was an association between NBS1 Glu185Gln polymorphism and lung cancer risk under the dominant comparison model (fixed-effects OR GluGln/GlnGln vs. GluGlu = 1.21, 95 % CI 1.07-1.37, P = 0.002, I (2) = 8.1 %). Subgroup analysis by race suggested a significant association between NBS1 Glu185Gln polymorphism and lung cancer risk in Asians (fixed-effects OR GluGlnGlnGln vs. GluGlu = 1.22, 95 % CI 1.06-1.41, P = 0.005) but not in Caucasians (fixed-effects OR GluGlnGlnGln vs. GluGlu = 1.17, 95 % CI 0.91-1.50, P = 0.220). This meta-analysis supports that there is an association between NBS1 Glu185Gln polymorphism and lung cancer risk. More studies are needed to further verify this association.

Family history of lung cancer in never smokers with non-small-cell lung cancer and its association with tumors harboring EGFR mutations

INTRODUCTION

Inherited susceptibility to lung cancer is understudied. Never smokers are an important subgroup of patients enriched for tumors harboring oncogene aberrations in the EGFR and ALK genes. We aimed to better characterize the incidence of family history of lung cancer among never smokers with NSCLC.

METHODS

Clinicopathologic data, tumor genotype, family history of cancer, and specifically family history of lung cancer from 230 consecutive never smokers was retrospectively compiled and analyzed.

RESULTS

In our cohort, the median age was 56 years, 67% were women, 75% were white, 59% had advanced NSCLC and 87% had adenocarcinoma histology. In these tumors, 98/230 (42%) had an EGFR mutation, 17/155 (11%) had KRAS mutations and 27/127 (21%) had an ALK translocation. Family history of any cancer was common (57%) and specific family history of lung cancer was present in 42/230 cases (18%). The percentage of cases with family history of lung cancer was higher in the EGFR mutated versus EGFR wild-type NSCLCs. Out of the cases with a family history of any cancer, 22/53 (41.5%) EGFR mutated, 1/5 (20%) KRAS mutated and 3/19 (15.5%) ALK translocated cohorts had a family history of lung cancer. The ratio of family history of lung cancer to family history of cancer was significantly higher in the EGFR mutated cohort when compared to the ALK translocated plus KRAS mutated cohorts (p=0.039).

CONCLUSIONS

Family history of lung cancer is common in never smokers with NSCLC, and there seems to be a particular link in families in which the proband has an EGFR mutated tumor when compared to ALK translocated or KRAS mutated tumors. Further study of families with EGFR-mutated NSCLC may yield insights into the pathogenesis of this tumor type.

Quantitative assessment of the effects of MMP-2 polymorphisms on lung carcinoma risk

BACKGROUND

Previous studies assessing associations between matrix metalloproteinase 2 (MMP-2) polymorphisms and lung cancer risk reported conflicting results. A meta-analysis was therefore performed to derive a more precise estimation.

METHOD

Case-control studies assessing associations between MMP-2 C735T and C1306T polymorphisms and lung cancer risk were included. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were estimated.

RESULTS

7 studies with a total of 3,189 lung cancer cases and 3,013 controls were finally included into this meta-analysis. Overall, the MMP-2 C735T polymorphism was associated with lung cancer risk under the homozygote model (CC versus TT: OR =1.44, 95% CI = 1.03-2.02, I2 = 0%), while the MMP- 2 C1306T polymorphism also associated demonstrated links with all four models (all P values less than 0.05). Subgroup analyses by race suggested obvious associations between MMP-2 C735T and C1306T polymorphisms and lung cancer risk in Asians but not in Caucasians. There was no evidence for publication bias.

CONCLUSION

Currently available evidence supports teh conclusion that MMP-2 C735T and C1306T polymorphisms influence susceptibility to lung cancer in Asians.

Explorations of lung cancer stigma for female long-term survivors

Lung cancer is the leading cause of cancer death in women, accompanied by greater psychological distress than other cancers. There is minimal but increasing awareness of the impact of lung cancer stigma (LCS) on patient outcomes. LCS is associated with increased symptom burden and decreased quality of life. The purpose of this study was to explore the experience of female long-term lung cancer survivors in the context of LCS and examine how participants discursively adhere to or reject stigmatizing beliefs. Findings situated within Cataldo and colleagues' theoretical model include: (1) addiction and tobacco marketing as possible precursors for LCS, (2) the possible role of expert providers as LCS enhancers, (3) response of overlapping complicated identity shifts, (4) simultaneous rejection and assumption of LCS, and (5) information control via advocacy activities as a LCS mitigation response. These findings expand the current understanding of LCS, and call for future conceptual exploration and theoretical revision, particularly with respect to the possibility of interaction between relevant/related stigma(s) and LCS. As the number of women living with lung cancer increases, with longer survival times, the effect of LCS and other experiences of discrimination on patient outcomes could be substantial.

Computed tomography screening for lung cancer: has it finally arrived? Implications of the national lung screening trial

The National Lung Screening Trial (NLST) has provided compelling evidence of the efficacy of lung cancer screening using low-dose helical computed tomography (LDCT) to reduce lung cancer mortality. The NLST randomized 53,454 older current or former heavy smokers to receive LDCT or chest radiography (CXR) for three annual screens. Participants were observed for a median of 6.5 years for outcomes. Vital status was available in more than 95% of participants. LDCT was positive in 24.2% of screens, compared with 6.9% of CXRs; more than 95% of all positive LDCT screens were not associated with lung cancer. LDCT detected more than twice the number of early-stage lung cancers and resulted in a stage shift from advanced to early-stage disease. Complications of LDCT screening were minimal. Lung cancer-specific mortality was reduced by 20% relative to CXR; all-cause mortality was reduced by 6.7%. The major harms of LDCT are radiation exposure, high false-positive rates, and the potential for overdiagnosis. This review discusses the risks and benefits of LDCT screening as well as an approach to LDCT implementation that incorporates systematic screening practice with smoking cessation programs and offers opportunities for better determination of appropriate risk cohorts for screening and for better diagnostic prediction of lung cancer in the setting of screen-detected nodules. The challenges of implementation are considered for screening programs, for primary care clinicians, and across socioeconomic strata. Considerations for future research to complement imaging-based screening to reduce the burden of lung cancer are discussed.

Significant association of 5p15.33 (TERT-CLPTM1L genes) with lung cancer in Chinese Han population

Lung cancer is a leading cause of cancer-related deaths throughout the world. Recent genome-wide association studies and consecutive validation supported that the 5p15.33 region containing telomerase reverse transcriptase gene (TERT) and cleft lip and palate transmembrane protein 1-like (CLPTM1L) gene showed significant association with lung cancer in multiple populations. Here we studied a large Chinese Han cohort consisting of 1759 cases and 1804 controls. In the 1st stage (784 cases versus 782 controls) we genotyped 13 tag SNPs within 5p15.33 region to further investigate the association. After the 2nd stage validation (975 cases versus 1022 controls), the study clarified the association that rs2736100 of the TERT gene conferred the highest significant risk of lung cancer (P=4×10(-3) in the 1st stage association, P=4×10(-4) in the 2nd stage validation, and P=1×10(-5), odds ratio=1.24 in the combined population). The results provided the evidence of a cross-race susceptibility of the lung cancer locus.

Effects of the cyclin D1 polymorphism on lung cancer risk--a meta-analysis

BACKGROUND

Cyclin D1 (CCND1) is critical in the transition of the cell cycle from G1 to S phases and unbalanced cell cycle regulation is a hallmark of carcinogenesis. A number of studies conducted to assess the association between CCND1 G870A polymorphism and susceptibility to lung cancer have yielded inconsistent and inconclusive results. In the present study, the possible association above was assessed by a meta-analysis.

METHODS

Eligible articles were identified for the period up to November 2011. Pooled odds ratios (OR) with 95% confidence intervals (95%CI) were appropriately derived from fixed effects or random-effects models. Sensitivity analysis excluding studies whose genotype frequencies in controls significantly deviated from the Hardy-Weinberg equilibrium (HWE) was performed.

RESULTS

Ten case-control studies with a total of 10,548 subjects were eligible. At the overall analysis the CCND1 870A allele appeared to be associated with elevated lung cancer risk (for allele model, pooled OR=1.24, 95% CI: 1.08-1.44, P=0.004; for homozygous model, pooled OR=1.45, 95% CI: 1.14-1.84, P=0.003; for recessive model, pooled OR=1.29, 95% CI: 1.06-1.58, P=0.013; for dominant model, pooled OR=1.33, 95% CI: 1.08-1.65, P=0.009). Subgroup analyses by ethnicity and sensitivity analysis further pointed to associations, particularly in Asians.

CONCLUSION

This meta-analysis suggests that the A allele of CCND1 G870A polymorphism confers additional lung cancer risk.

Ionizing radiation-induced γ-H2AX activity in whole blood culture and the risk of lung cancer

BACKGROUND

Phenotypic biomarkers of DNA damage repair may enhance cancer risk prediction. The γ-H2AX formed at the sites of double-strand break (DSB) after ionizing radiation is a specific marker of DNA damage.

METHODS

In an ongoing case-control study, the baseline and ionizing radiation-induced γ-H2AX levels in peripheral blood lymphocytes (PBL) from frequency-matched 306 untreated patients with lung cancer and 306 controls were measured by a laser scanning cytometer-based immunocytochemical method. The ratio of ionizing radiation-induced γ-H2AX level to the baseline was used to evaluate interindividual variation of DSB damage response and to assess the risk of lung cancer by using unconditional multivariable logistic regression with adjustment of age, sex, ethnicity, smoking status, family history of lung cancer, dust exposure, and emphysema.

RESULTS

The mean γ-H2AX ratio was significantly higher in cases than controls (1.46 ± 0.14 vs. 1.41 ± 0.12, P < 0.001). Dichotomized at the median in controls, high γ-H2AX ratio was significantly associated with increased risk of lung cancer [OR = 2.43; 95% confidence interval (CI): 1.66-3.56]. There was also a significant dose-response relationship between γ-H2AX ratio and lung cancer risk in quartile analysis. Analysis of joint effects with other epidemiologic risk factors revealed elevated risk with increasing number of risk factors.

CONCLUSION

γ-H2AX activity as shown by measuring DSB damage in ionizing radiation-irradiated PBLs may be a novel phenotypic marker of lung cancer risk.

IMPACT

γ-H2AX assay is a robust and quantifiable image-based cytometer method that measures mutagen-induced DSB response in PBLs as a potential biomarker in lung cancer risk assessment.

The use and misuse of biomedical data: is bigger really better?

Very large biomedical research databases, containing electronic health records (EHR) and genomic data from millions of patients, have been heralded recently for their potential to accelerate scientific discovery and produce dramatic improvements in medical treatments. Research enabled by these databases may also lead to profound changes in law, regulation, social policy, and even litigation strategies. Yet, is "big data" necessarily better data? This paper makes an original contribution to the legal literature by focusing on what can go wrong in the process of biomedical database research and what precautions are necessary to avoid critical mistakes. We address three main reasons for approaching such research with care and being cautious in relying on its outcomes for purposes of public policy or litigation. First, the data contained in biomedical databases is surprisingly likely to be incorrect or incomplete. Second, systematic biases, arising from both the nature of the data and the preconceptions of investigators, are serious threats to the validity of research results, especially in answering causal questions. Third, data mining of biomedical databases makes it easier for individuals with political, social, or economic agendas to generate ostensibly scientific but misleading research findings for the purpose of manipulating public opinion and swaying policymakers. In short, this paper sheds much-needed light on the problems of credulous and uninformed acceptance of research results derived from biomedical databases. An understanding of the pitfalls of big data analysis is of critical importance to anyone who will rely on or dispute its outcomes, including lawyers, policymakers, and the public at large. The Article also recommends technical, methodological, and educational interventions to combat the dangers of database errors and abuses.

Drug Resistance Mechanisms in Non-Small Cell Lung Carcinoma

Lung cancer is the most commonly diagnosed cancer in the world. “Driver” and “passenger” mutations identified in lung cancer indicate that genetics play a major role in the development of the disease, progression, metastasis and response to therapy. Survival rates for lung cancer treatment have remained stagnant at ~15% over the past 40 years in patients with disseminated disease despite advances in surgical techniques, radiotherapy and chemotherapy. Resistance to therapy; either intrinsic or acquired has been a major hindrance to treatment leading to great interest in studies seeking to understand and overcome resistance. Genetic information gained from molecular analyses has been critical in identifying druggable targets and tumor profiles that may be predictors of therapeutic response and mediators of resistance. Mutated or overexpressed epidermal growth factor receptor (EGFR) and translocations in the echinoderm microtubule-associated protein-like 4 (EML4)-anaplastic lymphoma kinase (ALK) genes (EML4-ALK) are examples of genetic aberrations resulting in targeted therapies for both localized and metastatic disease. Positive clinical responses have been noted in patients harboring these genetic mutations when treated with targeted therapies compared to patients lacking these mutations. Resistance is nonetheless a major factor contributing to the failure of targeted agents and standard cytotoxic agents. In this review, we examine molecular mechanisms that are potential drivers of resistance in non-small cell lung carcinoma, the most frequently diagnosed form of lung cancer. The mechanisms addressed include resistance to molecular targeted therapies as well as conventional chemotherapeutics through the activity of multidrug resistance proteins.

Association between a genome-wide association study-identified locus and the risk of lung cancer in Japanese population

BACKGROUND

Genome-wide association studies have identified 15q25 and 5p15 as lung cancer risk chromosomal regions in whites. The genetic structures of these loci differ between Asians and whites, however, indicating the need for additional studies in Asian populations. To examine the impact of 15p25 and 5p15 on lung cancer risk and smoking intensity, we conducted a case-control study in Japanese population. We also examined whether these loci modify the effect of smoking behavior on lung cancer risk.

METHODS

Subjects were 716 Japanese patients with lung cancer and 716 controls. Associations were examined by logistic regression models with adjustment for potential confounders.

RESULTS

We found that the variants of rs12914385 and rs931794 on 15q25 modified the effect of cumulative tobacco smoking on lung cancer risk but that these two loci showed no statistically significant main effects on lung cancer risk. Compared with never smoking without the risk allele of rs931794, odds ratio for heavy smoking without the risk allele was 4.03 (95% confidence interval: 2.45-6.62) and that with the risk allele was 8.09 (5.09-12.9), and the joint effect of rs931734 and cumulative tobacco consumption was statistically significant (pinteraction < 0.001). A similar impact was observed with rs12914385 at chromosome 15q25 (pinteraction = 0.021). Associations for the TERT-CLPM1L locus on 5p15 with lung cancer risk in Japanese patients were of a similar magnitude to those in whites.

CONCLUSIONS

These results support the contribution of 15q25 and 5p15 to lung cancer and indicate that the 15q25 region modifies the well-established effect of smoking on the risk of lung cancer in a Japanese population.

Cytogenetic findings in lung cancer that illuminate its biological history from adenomatous hyperplasia to bronchioalveolar carcinoma to adenocarcinoma: A case report

The biological and chronological evolution of lung cancer remain to be fully elucidated. A multi-step carcinogenesis hypothesis suggests a progression from atypical adenomatous hyperplasia (AAH) through bronchioalveolar carcinoma (BAC) to invasive adenocarcinoma (AC), but to date this has not been formally demonstrated. We report a case of a patient diagnosed by computed tomography (CT) with lung cancer in the superior right lobe who also presented with a pure ground-glass opacity (GGO) in the inferior lobe, while the middle lobe appeared normal. Following pneumonectomy, cytogenetic analysis successfully performed on spontaneous metaphases obtained by the direct method from samples of the three lung lobes showed the presence of three clonal cell populations, each progressively having increased karyotype complexity. Fluorescence in situ hybridization (FISH), performed using ALK (2p23) break probe and ALK/EML4 t(2;2);inv(2) fusion probe, showed a normal pattern for all specimens. Histological evaluation confirmed the presence of AC in the superior right lobe and classified the GGO lesion as BAC and the normal tissue of the middle lobe as AAH. To the best of our knowledge, this is the first case in which the cytogenetic study of spontaneous metaphases showed a clear clonal relationship among AC, BAC and AAH present simultaneously in different lobes of the same lung. This case appears to indicate that the entire lung was somehow predisposed to a neoplastic transformation starting with a diffuse AAH characterized by high proliferative activity. Moreover, the 5q13 region involved in the translocation shared by BAC and AC contains at least 4 genes encoding important regulators of the cell cycle that may be considered new molecular markers of lung cancer.

MMP1-1607 1G/2G polymorphism and lung cancer risk: a meta-analysis

Matrix metalloproteinase-1 (MMP-1) plays an important role in the breakdown of extracellular matrix and mediates pathways of apoptosis, angiogenesis, and immunity. It has been demonstrated that MMP-1 overexpression is associated with tumor initiation, invasion, and metastasis. Many studies have investigated the association between MMP1-1607 1G/2G polymorphism and lung cancer risk, but the impact of MMP1-1607 1G/2G polymorphism on lung cancer is unclear owing to the obvious inconsistence among those studies. This study aimed to quantify the strength of the association between MMP1-1607 1G/2G polymorphism and lung cancer risk. We searched the PubMed, Embase, and Wanfang databases for studies on the association between MMP1-1607 1G/2G polymorphism and risk of lung cancer. We estimated summary odds ratio (OR) with its corresponding 95 % confidence interval (95%CI) to assess the association. Overall, MMP1-1607 1G/2G polymorphism was associated with increased risk of lung cancer under four genetic models (OR(2G versus 1G) = 1.21, 95 %CI 1.06-1.37; OR(2G2G versus 1G1G) = 1.36, 95%CI 1.09-1.70; OR(2G2G versus 2G1G+1G1G) = 1.33, 95 %CI 1.10-1.61; and OR(2G2G+2G1G versus 1G1G) = 1.15, 95 %CI 1.04-1.27). Meta-analyses of studies with high quality showed that MMP1-1607 1G/2G polymorphism was still associated with lung cancer risk under those four genetic models. Subgroup analyses by ethnicity and sensitivity analyses further identified the significant association in East Asians. No evidence of publication bias was observed. Meta-analyses of available data show a significant association between MMP1-1607 1G/2G polymorphism and lung cancer risk.

Influence of common genetic variation on lung cancer risk: meta-analysis of 14 900 cases and 29 485 controls

Recent genome-wide association studies (GWASs) have identified common genetic variants at 5p15.33, 6p21-6p22 and 15q25.1 associated with lung cancer risk. Several other genetic regions including variants of CHEK2 (22q12), TP53BP1 (15q15) and RAD52 (12p13) have been demonstrated to influence lung cancer risk in candidate- or pathway-based analyses. To identify novel risk variants for lung cancer, we performed a meta-analysis of 16 GWASs, totaling 14 900 cases and 29 485 controls of European descent. Our data provided increased support for previously identified risk loci at 5p15 (P = 7.2 × 10(-16)), 6p21 (P = 2.3 × 10(-14)) and 15q25 (P = 2.2 × 10(-63)). Furthermore, we demonstrated histology-specific effects for 5p15, 6p21 and 12p13 loci but not for the 15q25 region. Subgroup analysis also identified a novel disease locus for squamous cell carcinoma at 9p21 (CDKN2A/p16(INK4A)/p14(ARF)/CDKN2B/p15(INK4B)/ANRIL; rs1333040, P = 3.0 × 10(-7)) which was replicated in a series of 5415 Han Chinese (P = 0.03; combined analysis, P = 2.3 × 10(-8)). This large analysis provides additional evidence for the role of inherited genetic susceptibility to lung cancer and insight into biological differences in the development of the different histological types of lung cancer.