Role In Lung Cancer Susceptibility Research Articles

Genetic polymorphisms in the mEHgene in relation to tobacco smoking: role in lung cancer susceptibility and survival in north Indianpatients withlungcancerundergoing platinum-based chemotherapy.

Aim: Epoxide hydrolase is involved in oxidative defenses and isresponsible for the activation of carcinogens. The relationship between EPHX1 polymorphisms (Tyr113His and His139Arg)and overall survival (OS) and lung cancer (LC) riskwas investigated. Methods: The study comprised 550 cases and 550 controls. Genotyping and statistical analysis were applied. Results: The variant genotypes of EPHX1 polymorphisms exhibited no association with LC risk. The Tyr113His polymorphism exhibited twofold increased odds of lymph node invasion (p=0.04). The Tyr/His genotype is a risk factor for smokers. Subjects carrying thecombined genotype for His139Arg showed better median survival time(MST)and theheterozygous genotype revealed better MST in the case of small-cell lung cancer(SCLC; 11.30 vs 6.73months;log-rank test: p=0.02). The heterozygous genotype (His139Arg) had longer MST in patients receiving cisplatin/carboplatin and irinotecan (11.30 vs 7.23;log-rank test: p=0.007) Conclusion: The Tyr113His polymorphism is associated with LC risk in smokers and is a potential prognostic factor for OS inpatients withSCLCafter irinotecan.

Immune-mediated genetic pathways resulting in pulmonary function impairment increase lung cancer susceptibility

Impaired lung function is often caused by cigarette smoking, making it challenging to disentangle its role in lung cancer susceptibility. Investigation of the shared genetic basis of these phenotypes in the UK Biobank and International Lung Cancer Consortium (29,266 cases, 56,450 controls) shows that lung cancer is genetically correlated with reduced forced expiratory volume in one second (FEV1: rg = 0.098, p = 2.3 × 10−8) and the ratio of FEV1 to forced vital capacity (FEV1/FVC: rg = 0.137, p = 2.0 × 10−12). Mendelian randomization analyses demonstrate that reduced FEV1 increases squamous cell carcinoma risk (odds ratio (OR) = 1.51, 95% confidence intervals: 1.21–1.88), while reduced FEV1/FVC increases the risk of adenocarcinoma (OR = 1.17, 1.01–1.35) and lung cancer in never smokers (OR = 1.56, 1.05–2.30). These findings support a causal role of pulmonary impairment in lung cancer etiology. Integrative analyses reveal that pulmonary function instruments, including 73 novel variants, influence lung tissue gene expression and implicate immune-related pathways in mediating the observed effects on lung carcinogenesis.

Association between IL-1R2 polymorphisms and lung cancer risk in the Chinese Han population: A case-control study.

BackgroundInterleukin‐1 receptor 2 (IL‐1R2), as an anti‐inflammatory cytokine, is involved in the pathogenesis and progression of lung cancer. However, the role of IL‐1R2 polymorphisms in patients with lung cancer has yet to be fully elucidated.MethodsSix single‐nucleotide polymorphisms (SNPs) in IL‐1R2 were genotyped in 259 patients and 346 healthy controls. We used the chi‐squared test, genetic model analysis, Haploview analysis, and multifactor dimensionality reduction (MDR) to evaluate the potential association between IL‐1R2 polymorphisms and lung cancer susceptibility. Bioinformatics analyses were conducted to analyze the expression level of IL‐1R2 and its association with the overall survival of lung cancer.ResultsOur results found that rs3218977‐GG was associated with a decreased risk of lung cancer (odds ratio [OR] = 0.39; 95% confidence interval [CI]: 0.17–0.87; p = 0.023), and rs2072472 had a significant risk‐increasing effect in the dominant model (AG + GG vs. AA: OR = 1.54; 95% CI: 1.09–2.20; p = 0.015). The MDR model also revealed that rs2072472 is the most influential risk factor of lung cancer (testing accuracy = 0.543; cross‐validation consistency = 10/10; p = 0.032). In addition, our results indicated that the IL‐1R2 mRNA level was downregulated in lung cancer patients, whereas the high expression of IL‐1R2 was related to a poor prognosis in lung cancer.ConclusionsOur results suggest that genetic variants of IL‐1R2 may play a role in lung cancer susceptibility. Further population and functional validations of our findings are warranted.

Association between p73 gene G4C14-to-A4T14 polymorphism and risk of lung cancer: A meta-analysis.

To explore the correlation between p73 G4C14-to-A4T14 polymorphism and lung cancer risk. The meta analysis was conducted from October 2017 to March 2018, and comprised studies published till March 27, 2018, that addressed the relationship between the p73 G4C14-to-A4T14 polymorphism and risk of lung cancer, and were available on databases including PubMed, Web of Science, Embase, Cochrane Library and China National Knowledge Infrastructure. Pooled odds ratio with corresponding 95% confidence interval and subgroup analysis between ethnicities were carried out to assess the association between the two parameters using four different models. Stata 12 was used for data analysis. For overall population, there was no significant risk of lung cancer for the polymorphism under allele and dominant genetic models. However, reduced risks were found under homozygous (AT/AT vs GC/GC; p=0.02) and recessive (AT/AT vs GC/AT + GC/GC; p=0.02) comparison models. Subgroup analysis between ethnicities demonstrated reduced risk of lung cancer for the polymorphism under the four genetic comparison models for Asian population, but increased risk for the Caucasian group. AT/AT variant carriers possessed reduced susceptibility of lung cancer in the general population. Ethnic differences for the p73 gene polymorphism played an important role in lung cancer susceptibility.

Polymorphisms in the microsomal epoxide hydrolase gene: role in lung cancer susceptibility and prognosis.

The aim of this study was to investigate the relationship between EPHXI exon 3 Tyr113His and exon 4 His139Arg polymorphisms, predicted microsomal epoxide hydrolase (mEH) activity, and lung cancer development. mEH is a protective enzyme involved in oxidative defences against a number of environmental chemicals and pollutants, but it is also responsible for the xenobiotic activation of carcinogens. We investigated the two polymorphisms of the mEH gene (EPHX1) in 58 lung cancer patients and 41 controls using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The exon 3 Tyr113His polymorphism was associated with lung cancer (P < 0.001). The frequency of the His113His homozygote genotype in exon 3 was significantly increased in patients compared with controls (P < 0.001). In contrast, there was no significant difference in exon 4 polymorphisms between patients and controls. When the exon 3 and 4 polymorphisms were considered together, the combined EPHX1 His113His113/His139His139 genotype (very low predicted enzyme activity) was found to be associated with an increased risk of lung cancer (P = 0.044, OR = 3.063, CI = 0.932-10.069). We observed that patients with T3 + T4 tumors had an approximately 3-fold higher risk of the Tyr113/His113 genotype than patients with T1 + T2 tumors. Lung cancer patients carrying a heterozygote Tyr113/His 113 genotype had a 2-fold increased risk of lymph node metastases (P = 0.051). These findings suggest that the exon 3 Tyr113His and exon 4 His139Arg polymorphisms of EPHXI may be associated with a increased risk of lung cancer and a worse prognosis.

CYP1A1 gene polymorphisms and smoking status as modifier factors for lung cancer risk

Lung cancer remains the most prevalent malignancy worldwide. Susceptibility to lung cancer has been shown to be modulated by inheritance of polymorphic genes. Several metabolic enzymes are currently under investigation for their possible role in lung cancer susceptibility, including members of the cytochrome P450 (CYP) superfamily. The aim of this work was to identify the correlation between CYP1A1 m1 and m2 polymorphisms and lung cancer risk and figure its interactions with smoking as genetic modifiers in the etiology of lung cancer in the Egyptian population. One hundred and ten patients with lung cancer and one hundred and ten controls were enrolled in the study. CYP1A1 m1 and m2 polymorphisms were determined using polymerase chain reaction restriction fragment length polymorphism. Subjects carrying TC and CC genotypes of CYP1A1 m1 and AG and GG genotypes of CYP1A1 m2 were significantly more likely to develop lung cancer especially squamous cell carcinoma. The proportion of lung cancer attributable to the interaction of smoking and CYP1A1 m1 and CYP1A1 m2 polymorphisms was 32% and 52% respectively. Our results revealed that CYP1A1 m1 and m2 polymorphisms contribute to smoking related lung cancer risk in the Egyptian population.

Polymorphism Arg72Pro of p53 Confers Susceptibility to Squamous Cell Carcinoma of Lungs in a North Indian Population

The causes of lung cancer might be many, but genetic variation in the genes of carcinogen-metabolizing enzymes, tumor suppressor proteins, and/or DNA-repairing enzymes can also play a significant role in lung cancer susceptibility. The tumor suppressor protein p53 functions to induce cell cycle arrest, DNA repair, or apoptosis. Polymorphism in its gene can, therefore, play a significant role in cancer susceptibility. Present report evaluated the association of polymorphism in exon 4 Arg72Pro (G>C) of the p53 gene with lung cancer susceptibility using 175 cancer cases and 202 controls from the North Indian population. Binary logistic regression analysis revealed that the Pro72Pro genotype was significantly associated with increasing risk for lung cancer in younger age patients (≤55 years) (adjusted odds ratio [OR]=2.72, 95% confidence intervals [95% CI] 0.99-7.85, p<0.05). Histological stratification of lung cancer revealed that the Pro72Pro genotype was associated with higher risk for squamous cell carcinoma (OR=3.05, 95% CI 1.07-8.87, p<0.05). Genetic variation Arg72Pro of the p53 gene may contribute to higher risk of SCC of lung in the North Indian population.

Genetic variation of the natural killer gene complex has a role in lung cancer susceptibility.

Worldwide estimates indicate lung cancer is the leading cause of death among all cancers, while also being the most frequently diagnosed of new cancer cases (1). Non-small cell lung carcinoma is the most frequent subtype. Exposure to environmental carcinogens, such as radon and tobacco inhalation, is a major risk factor for developing lung cancer. Familial heredity also increases an individual’s risk, although the impact of genetic factors on the development of lung cancer remains unclear, especially within the context of immune response. Innate and adaptive immune systems may inhibit or enhance carcinogenesis depending on the recruitment of specific immunocompetent cells (2).

Polymorphisms in the Microsomal Epoxide Hydrolase Gene: Role in Lung Cancer Susceptibility and Prognosis

The aim of this study was to investigate the relationship between EPHXI exon 3 Tyr113His and exon 4 His139Arg polymorphisms, predicted microsomal epoxide hydrolase (mEH) activity, and lung cancer development. mEH is a protective enzyme involved in oxidative defences against a number of environmental chemicals and pollutants, but it is also responsible for the xenobiotic activation of carcinogens. We investigated the two polymorphisms of the mEH gene (EPHX1) in 58 lung cancer patients and 41 controls using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The exon 3 Tyr113His polymorphism was associated with lung cancer (P < 0.001). The frequency of the His113His homozygote genotype in exon 3 was significantly increased in patients compared with controls (P < 0.001). In contrast, there was no significant difference in exon 4 polymorphisms between patients and controls. When the exon 3 and 4 polymorphisms were considered together, the combined EPHX1 His113His113/His139His139 genotype (very low predicted enzyme activity) was found to be associated with an increased risk of lung cancer (P = 0.044, OR = 3.063, CI = 0.932-10.069). We observed that patients with T3 + T4 tumors had an approximately 3-fold higher risk of the Tyr113/His113 genotype than patients with T1 + T2 tumors. Lung cancer patients carrying a heterozygote Tyr113/His 113 genotype had a 2-fold increased risk of lymph node metastases (P = 0.051). These findings suggest that the exon 3 Tyr113His and exon 4 His139Arg polymorphisms of EPHXI may be associated with a increased risk of lung cancer and a worse prognosis.

3502 HOGG1 Ser326Cys polymorphism plays a role in lung cancer susceptibility: Analyses stratified by histologic type and smoking status

Parkinson's disease (PD) is one of the most common neurodegenerative disorders characterized by progressive and profound loss of dopaminergic neurons in the substantia nigra (SN) resulting in resting tremor, rigidity, bradykinesia, and postural instability. The primary cause of the disease is still unknown, but mitochondrial dysfunction and oxidative stress have been implicated in the neurodegenerative process. Oxoguanine DNA glycosylase (OGG1) removes oxidized guanine (8-oxo-G) from the DNA, thus reducing the mutagenic potential of this modified base. Increased 8-oxo-G levels and up-regulation of OGG1 have been detected in the SN of PD brains. Moreover, studies performed in OGG1 knockout mice revealed the importance of this enzyme in protecting dopaminergic neurons against the accumulation of oxidative DNA damage. A common Ser326Cys polymorphism is known in the human gene encoding OGG1 (hOGG1), and the mutant Cys326 variant has been associated with reduced glycosylase activity. In the present study we screened 139 sporadic PD patients and 211 healthy matched controls for the presence of the hOGG1 Ser326Cys polymorphism. The Cys326 allele frequency was similar between the groups (0.20 in PD patients and 0.19 in controls; p = 0.817), and no difference in genotype frequencies was observed. Moreover, the hOGG1 Ser326Cys polymorphism was not associated with disease age at onset (p = 0.791). Overall, present results suggest that the hOGG1 Ser326Cys polymorphism is not associated with sporadic PD.

Genetic variants in the MDM2 promoter and lung cancer risk in a Chinese population

Overexpression of MDM2 may attenuate the P53 stress response pathway through direct blocking of P53 transcriptional activity and mediating P53 degradation. Two promoter polymorphisms (one is a T to G substitution at the intronic P53-response promoter, and the other is a 40-bp insertion/deletion polymorphism in the constitutive promoter) were identified, and recently the T/G substitution (SNP309) has been demonstrated to alter the levels of MDM2 gene products. In this molecular epidemiological study with 717 incident lung cancer cases and 1,083 cancer-free controls, we genotyped these 2 promoter polymorphisms of MDM2 and evaluated their associations with risk of lung cancer. We found that there were no significant associations between MDM2 SNP309 variant genotypes and lung cancer risk (adjusted OR = 1.20, 95% CI = 0.95-1.53 for TG and adjusted OR = 1.12, 95% CI = 0.85-1.48 for GG, respectively). Similarly, we did not find evidence for any association between risk of lung cancer and MDM2 insertion/deletion polymorphism. The findings suggest that these two MDM2 promoter polymorphisms may not play a major role in lung cancer susceptibility in this Chinese population.

Polymorphisms in the DNA nucleotide excision repair genes and lung cancer risk in Xuan Wei, China

The lung cancer mortality rate in Xuan Wei County is among the highest in China and has been attributed to exposure to indoor smoky coal emissions that contain very high levels of polycyclic aromatic hydrocarbons (PAHs). Nucleotide excision repair (NER) plays a key role in reversing DNA damage from exposure to environmental carcinogens, such as PAHs, that form bulky DNA adducts. We studied single nucleotide polymorphisms (SNPs) and their corresponding haplotypes in 6 genes (ERCC1, ERCC2/XPD, ERCC4/XPF, ERCC5/XPG, RAD23B and XPC) involved in NER in a population-based case-control study of lung cancer in Xuan Wei. A total of 122 incident primary lung cancer cases and 122 individually matched controls were enrolled. Three linked SNPs in ERCC2 were associated with lung cancer with similar ORs; e.g., persons with the Gln allele at codon 751 had a 60% reduction of lung cancer (OR = 0.40, 95% CI 0.18-0.89). Moreover, one haplotype in ERCC2 was associated with a decreased risk of lung cancer (OR = 0.40, 95% CI 0.19-0.85) compared to the most common haplotype. In addition, subjects with one or 2 copies of the Val allele at codon 249 of RAD23B had a 2-fold increased risk of lung cancer (OR = 1.91, 95% CI 1.12-3.24). In summary, our results suggest that genetic variants in genes involved in the NER pathway may play a role in lung cancer susceptibility in Xuan Wei. However, due to the small sample size, additional studies are needed to evaluate these associations within Xuan Wei and in other populations with substantial environmental exposure to PAHs.

‘Comparison of extremes’ approach provides evidence against the modifying role of NAT2 polymorphism in lung cancer susceptibility

NAT2 (arylamine N-acetyltransferase 2) polymorphism, being a key determinant of individual variations in acetylation capacity, is suspected to modify the risk of carcinogen-related malignancies. As tobacco smoke and other inhaled hazards contain a variety of NAT2 substrates, the relationship between NAT2 phenotype and lung cancer (LC) risk has been a subject of intensive research, however different case–control studies produced controversial data. In the present report, we employed a novel ‘comparison of extremes’ approach, i.e. we compared the distribution of NAT2 genotypes in lung cancer patients (LC, n=178) not only to the population controls (healthy donors (HD), n=364), but also to the subjects with a putative cancer-resistant constitution (elderly tumor-free smokers and non-smokers (ED), n=351). Frequencies of homozygous rapid, heterozygous rapid and slow acetylators were 6, 39 and 56% in LC, 8, 32 and 60% in HD, and 6, 35 and 59% in ED, respectively. Comparison of the NAT2 genotype frequencies between affected and non-affected individuals did not reveal any statistical deviations, irrespectively of smoking history, gender, age, or histological type of LC. Adjusted odds ratio for rapid vs. slow acetylators was 1.12 (95% confidence intervals (CI): 0.73–1.74) comparing LC vs. HD, and 1.10 (95% CI: 0.74–1.62) comparing LC vs. ED. Similar distribution of NAT2 acetylator genotypes both in tumor-prone and in tumor-resistant groups suggests that, despite the presence of NAT2 carcinogenic substrates in tobacco smoke, NAT2 polymorphism does not play a noticeable role in lung cancer susceptibility.

Dinucleotide polymorphism of p73 gene is associated with a reduced risk of lung cancer in a Chinese population

p73, a structural and functional homologue of p53, shares some p53-like tumor suppressor activity but also possesses oncogenic activity. Therefore, p73 plays an important role in modulating cell-cycle control and apoptosis. A potentially functional dinucleotide polymorphism, G4C14-to-A4T14, has been identified in the 5' untranslated region (UTR) of exon 2 of the p73 gene, which may theoretically form a stem-loop structure and affect gene expression. To test the hypothesis that these 2 common variants play a role in lung cancer susceptibility, we conducted a case-control study of 425 lung cancer patients and 588 cancer-free controls frequency-matched to the cases on age and sex in a Chinese population. The results showed that these 2 polymorphisms were in complete linkage disequilibrium and the frequencies of variant p73 AT haplotype (A4T14) were less common in the cases (0.225) than in the controls (0.287) (p = 0.0018), suggesting that this AT haplotype was protective against lung cancer. Compared to the p73 GC/GC homozygotes, both the AT/AT variant homozygotes and GC/AT heterozygotes were associated with a significantly decreased risk (adjusted OR: 0.45, 95% CI: 0.26-0.80 and OR: 0.70, 95% CI: 0.53-0.92, respectively). These results suggest that this p73 dinucleotide polymorphism may have a role in lung cancer susceptibility in our study population. Further studies are needed to elucidate potential functional relevance of the p73 AT variant allele.

Genetic polymorphisms of glutathione S-transferases as modulators of lung cancer susceptibility

Some of the glutathione S-transferases (GSTs) are polymorphic and may play a role in lung cancer susceptibility. Our previous study in a French Caucasian study population suggested GSTM1 null genotype as a moderate risk factor for lung cancer. Here we extended the study to investigate the potential role of GSTT1 and GSTP1 polymorphisms in susceptibility to lung cancer, either separately or in combination. The study population consisted of 268 controls and 251 cases. Nineteen percent of the controls and 15% of the cases had GSTT1 null genotype. The distribution of GSTP1*A/*A, *A/*B and *B/*B genotypes were 46.9, 45.5 and 7.6% in controls, and 47.8, 40.2 and 12.0% in cases, respectively. No statistically significant effects in the lung cancer risk were observed for the GSTT1 genotypes, but the GSTP1*B/*B genotype posed a 2-fold risk [odds ratio (OR) = 2.0, 95% confidence interval (CI) 1.0-4.1] of this malignancy compared with the GSTP1*A allele containing genotypes; this association was mainly attributable to small cell lung cancer (OR = 3.6, 95% CI 1.3-9.8). The most remarkable risk was seen for the small cell carcinoma among subjects with the GSTP1*B/*B genotype and concurrent lack of the GSTM1 gene (OR = 6.9, 95% CI 1.6-30.2). The deficient genotypes for GSTM1 and GSTP1 seem thus to be important risk modifiers for lung cancer, especially in combination.

Cyclooxygenase-2 expression is abundant in alveolar type II cells in lung cancer-sensitive mouse strains and in premalignant lesions

Overexpression of cyclooxygenase-2 (COX-2) is seen in a high percentage of human colon tumors, lung adenocarcinomas and other cancers. Inhibition of this enzyme represses human colon tumorigenesis and decreases lung tumor multiplicity in 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone-exposed A/J mice. The purpose of this investigation was to characterize the expression of cyclooxygenase-2 (COX-2) during tumor progression in the A/J mouse lung and to compare the results with expression in other cancer-susceptible and several cancer-resistant mouse strains. Analysis of normal A/J mouse lung showed that type II alveolar epithelial cells express high levels of COX-2 protein and mRNA, indicating that COX-2 is present constitutively in this tumor progenitor cell prior to any carcinogen exposure. Examination of lung-cancer-resistant (C3H/HeJ, C57BL/6J, DBA/2J) and other lung-cancer-susceptible (A/WySnJ, SWR/J) strains showed similar levels of COX-2 mRNA expression in the three susceptible strains and lower levels of expression in two of the resistant strains, indicating a possible correlation between COX-2 expression in type II cells and lung cancer susceptibility. COX-2 protein expression was observed in A/J lung tumors at all stages of development. Variation and occasional absence of protein expression were also observed in A/J lung tumors, particularly in adenomas and adenocarcinomas, suggesting that COX-2 is not obligatory for maintenance of the malignant phenotype. In support of this conclusion, treatment of xenografted cell lines derived from malignant murine pulmonary tumors with COX-2 inhibitors produced only a slight repression of growth. However, the frequent expression of COX-2 in early lesions in the A/J mouse lung combined with the known reduction in tumor number in animals treated with COX-2 inhibitors prior to carcinogen exposure indicate that COX-2 could be a promising target for lung cancer chemoprevention. In addition, high levels of COX-2 expression in the normal tumor-progenitor cells of lung-cancer-sensitive mice indicate that COX-2 may play a role in lung cancer susceptibility.

Cyclooxygenase-2 expression is abundant in alveolar type II cells in lung cancer-sensitive mouse strains and in premalignant lesions

Overexpression of cyclooxygenase-2 (COX-2) is seen in a high percentage of human colon tumors, lung adenocarcinomas and other cancers. Inhibition of this enzyme represses human colon tumorigenesis and decreases lung tumor multiplicity in 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone-exposed A/J mice. The purpose of this investigation was to characterize the expression of cyclooxygenase-2 (COX-2) during tumor progression in the A/J mouse lung and to compare the results with expression in other cancer-susceptible and several cancer-resistant mouse strains. Analysis of normal A/J mouse lung showed that type II alveolar epithelial cells express high levels of COX-2 protein and mRNA, indicating that COX-2 is present constitutively in this tumor progenitor cell prior to any carcinogen exposure. Examination of lung-cancer-resistant (C3H/HeJ, C57BL/6J, DBA/2J) and other lung-cancer-susceptible (A/WySnJ, SWR/J) strains showed similar levels of COX-2 mRNA expression in the three susceptible strains and lower levels of expression in two of the resistant strains, indicating a possible correlation between COX-2 expression in type II cells and lung cancer susceptibility. COX-2 protein expression was observed in A/J lung tumors at all stages of development. Variation and occasional absence of protein expression were also observed in A/J lung tumors, particularly in adenomas and adenocarcinomas, suggesting that COX-2 is not obligatory for maintenance of the malignant phenotype. In support of this conclusion, treatment of xenografted cell lines derived from malignant murine pulmonary tumors with COX-2 inhibitors produced only a slight repression of growth. However, the frequent expression of COX-2 in early lesions in the A/J mouse lung combined with the known reduction in tumor number in animals treated with COX-2 inhibitors prior to carcinogen exposure indicate that COX-2 could be a promising target for lung cancer chemoprevention. In addition, high levels of COX-2 expression in the normal tumor-progenitor cells of lung-cancer-sensitive mice indicate that COX-2 may play a role in lung cancer susceptibility.