Lung Cancer In Nonsmokers Research Articles

Epigenomic analysis of lung adenocarcinoma reveals novel DNA methylation patterns associated with smoking

The importance of epigenetic regulation has been increasingly recognized in the development of cancer. In this study, we investigated the impact of smoking, a major risk factor of lung cancer, on DNA methylation by comparing the genome-wide DNA methylation patterns between lung adenocarcinoma samples from six smokers and six nonsmokers. We identified that smoking-induced DNA methylations were enriched in the calcium signaling and neuroactive ligand receptor signaling pathways, which are closely related to smoking-induced lung cancers. Interestingly, we discovered that two genes in the mitogen-activated protein kinase signaling pathway (RPS6KA3 and ARAF) were hypomethylated in smokers but not in nonsmokers. In addition, we found that the smoking-induced lung cancer-specific DNA methylations were mostly enriched in nuclear activities, including regulation of gene expression and chromatin remodeling. Moreover, the smoking-induced hypermethylation could only be seen in lung adenocarcinoma tissue but not in adjacent normal lung tissue. We also used differentially methylated DNA loci to construct a diagnostic model to distinguish smoking-associated lung cancer from nonsmoking lung cancer with a sensitivity of 88.9% and specificity of 83.2%. Our results provided novel evidence to support that smoking can cause dramatic changes in the DNA methylation landscape of lung cancer, suggesting that epigenetic regulation of specific oncogenic signaling pathways plays an important role in the development of lung cancer.

Lung cancer in non-smokers

The decrease in lung cancer mortality in many Western societies is being attributed to a large extent to smoking prevention measures. However, lung cancer also occurs in non-smokers, with an estimated frequency of 10–25%. The identification of oncogenic driver alterations which are successfully targetable, being more prevalent in lung cancer in non-smokers, has encouraged interest in these tumors. The current knowledge on the molecular alterations in lung tumors of patients who have never smoked is summarised in the article of Drs. Subramanian and Govindan. Smoking prevention is of particular importance for pregnant women. The effect of in-utero exposure to tobacco smoke is a growing area of research in the field of passive smoking. Current knowledge on its potential health consequences is summarised by Dr. Nawroth and colleagues.

Genetic Variations in TERT-CLPTM1L Genes and Risk of Lung Cancer in Chinese Women Nonsmokers

BackgroundThe TERT gene is the reverse transcriptase component of telomerase and is essential for the maintenance of telomere DNA length, chromosomal stability and cellular immortality. CLPTM1L gene encodes a protein linked to cisplatin resistance, and it is well conserved and express in various normal or malignant tissues, including lung.MethodsTo test this hypothesis, we genotyped for two significant SNPs TERT-rs2736098 and CLPTM1L-rs4016981 in a case-control study with 501 cancer cases and 576 cancer-free controls in Chinese nonsmoking population. Information concerning demographic and risk factors was obtained for each case and control by a trained interviewer. Gene polymorphisms were determined by TaqMan methodology.ResultsWe found that the homozygous variant genetic model of TERT gene was associated with a significantly increased risk of lung cancer with adjusted OR of 1.72(95%CI = 1.19–2.51, P = 0.004 for heterogeneity). The joint effect of TERT and CLPTM1L increased risk for lung cancer with adjusted OR is 1.31(95%CI = 1.00–1.74, P = 0.052 for heterogeneity).ConclusionGenetic variants in TERT and CLPTM1L may affect the susceptibility of lung cancer, especially adenocarcinoma in Chinese women nonsmokers.

Associations of CYP1A1, GSTM1 and GSTT1 Polymorphisms with Lung Cancer Susceptibility in a Northern Indian Population

Susceptibility to lung cancer has been shown to be modulated by inheritance of polymorphic genes encoding cytochrome P450 1A1 (CYP1A1) and glutathione S transferases (GSTM1 and GSTT1), which are involved in the bioactivation and detoxification of environmental toxins. This might be a factor in the variation in lung cancer incidence with ethnicity. We conducted a case-control study of 218 northern Indian lung cancer patients along with 238 healthy controls, to assess any association between CYP1A1, GSTM1 and GSTT1 polymorphisms, either separately or in combination, with the likelihood of development of Lung cancer in our population. We observed a significant difference in the GSTT1 null deletion frequency in this population when compared with other populations (OR=1.87, 95%CI: 1.25-2.80-0.73, P=0.002). However, GSTM1 null genotype was found associated with lung cancer in the non-smoking subgroup. (P=0.170). Our study showed the GSTT1 null polymorphism to be associated with smoking-induced lung cancer and the GSTM1 null polymorphism to have a link with non-smoking related lung cancer.

Abstract 1502: Urinary biomarkers of polycyclic aromatic hydrocarbon and volatile organic carcinogens in relation to lung cancer development in lifelong never smokers - The Shanghai Cohort Study.

Abstract Background: In the United States, 10-15% of lung cancer victims are lifelong never smokers. Non-smoking related lung cancer alone ranks as the 6th most frequently diagnosed cancer. The etiological factors for non-smoking lung cancer are unclear. Although strong evidence supports a major role for polycyclic aromatic hydrocarbon (PAH) as causes of lung cancer in smokers, epidemiological studies prospectively investigating biomarkers of PAH and volatile organic carcinogens in relation to lung cancer risk among never smokers are lacking. Methods: A nested case-control study of lung cancer among never smokers was conducted within the Shanghai Cohort Study, a prospective cohort of 18,244 Chinese men aged 45-64 years at enrollment during 1986-1989. After more than 20 years of follow-up, we identified 96 incident lung cancer cases among never smokers. For each case, we randomly chose one control among cohort participants who were never smokers. The control was matched to the index case by age (±2 years), date of urine collection (±1 month) and neighborhood of residence. We quantified urinary free cotinine, 3-hydroxyphenanthrene (3-OH-Phe), total hydroxyphenanthrenes (the sum of 1-, 2-, 3-, and 4-OH-Phe) (total OH-Phe), r-1,t-2,3,c-4-tetrahdroxy-1,2,3,4-tetrahydrophenanthrene (PheT), mercapturic acid metabolites of acrolein [3-hydroxypropyl mercapturic acid (HPMA)], benzene [S-phenyl mercapturic acid (SPMA)], crotonaldehyde [4-hydroxybut-2-yl mercapturic acid (HBMA)], and ethylene oxide [2-hydroxyethyl mercapturic acid (HEMA)]. Self-reported never smokers whose urinary free cotinine was greater than 20 ng/ml were excluded from the present analysis for their potential use of tobacco. The odds ratio (OR) and 95% confidence interval (CI) for lung cancer for each urinary biomarker was estimated using an unconditional logistic regression method. Results: Among never smokers, urinary levels of all 3 measured PAH biomarkers were statistically significantly higher in cases than controls. The geometric means (pmol/mg creatinine) of total OH-Phe, 3-OH-Phe and PheT were 19.10 (in cases) vs 16.08 (in controls) (P = 0.017); 6.64 vs 5.44 (P = 0.011); and 19.84 vs 16.10 (P = 0.035), respectively. Compared with the lowest quartile, ORs (95% CIs) for lung cancer for the highest quartile were 2.59 (1.01-6.65) for total OH-Phe, 3.10 (1.12-7.75) for 3-OH-Phe, and 2.98 (1.13-7.87) for PheT (all Ptrend <0.05). There was no statistically significant difference in urinary levels of HPMA, SPMA, HBMA and HEMA between cases and controls. Conclusion: This is the first prospective study that demonstrates a positive association between urinary biomarkers of PAH and lung cancer risk among never smokers. Given its ubiquitous presence in the environment, PAH could account for large proportion of non-smoking related lung cancer. 1 Citation Format: Jian-Min Yuan, Yu-Tang Gao, Sharon Murphy, Steven G. Carmella, Renwei Wang, Heather H. Nelson, Stephen S. Hecht. Urinary biomarkers of polycyclic aromatic hydrocarbon and volatile organic carcinogens in relation to lung cancer development in lifelong never smokers - The Shanghai Cohort Study. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1502. doi:10.1158/1538-7445.AM2013-1502

Abstract 2655: Inhibitor of Differentiation/DNA binding (ID) proteins modulate the stem-like features of NSCLC cells by regulating the expression of Oct4, Sox2 and Nanog.

Abstract Non-small cell lung cancer (NSCLC) accounts for 85% of total lung cancer cases and demonstrates a strong association with tobacco use. The overall survival rate for NSCLC patients diagnosed in the late stages of cancer is very low, demonstrating the need for novel therapeutic strategies to combat this disease. While the genetic changes contributing to lung cancer in smokers and non-smokers are fairly well characterized, the downstream signaling events involved in tumorigenesis are not fully understood. Our laboratory had identified the transcriptional regulator, ID1 (inhibitor of differentiation/DNA binding 1), as a common mediator of oncogenesis in NSCLC, irrespective of the smoking history. NSCLC tumors are heterogeneous and are either refractory to the available treatments or develop resistance to therapy. Cancer stem cells (CSC) hypothesis has emerged as an explanation for tumor initiation, drug resistance and metastasis. CSCs have been shown to have tumor initiating properties.Given that the ID gene family (ID1- ID4) is known to be expressed in the embryonic progenitor cells and have been have been suggested to promote self renewal capacity of embryonic stem cells, and since ID proteins are known to promote the genesis of NSCLC, we examined whether these proteins contribute to the stemness of NSCLC CSCs. Side-population (SP) cells with CSC properties were isolated from four different NSCLC lines using flow cytometric sorting based on Hoechst 33342 exclusion. The mRNA and protein expression of the ID1-4 genes was assessed in the sorted SP cells from these cell lines and compared to the main population (MP) cells. Among the four ID proteins, ID3 expression was found to be comparatively higher in the SP cells compared to MP cells from all the cell lines; there was a difference in the levels of other family members as well. Depletion of ID3 expression by siRNAs led to a decrease in SP frequency; further, this led to a reduced expression of embryonic stem cell transcription factors Sox2, Oct4 and Nanog expression. Similar results were obtained when ID1 was depleted as well. Interestingly, depletion of ID1 or ID3 significantly impaired the ability of SP cells to self-renew, as measured by sphere formation assays. Further analysis suggests that the transcriptional co-repressor ZBP89 might be involved in the ID-mediated repression of the ES cell transcription factors. Our findings suggest that Id proteins might play a role in the maintenance of stem like properties in NSCLC CSCs and this is facilitated by the regulation of ES cell transcription factors in a ZBP89-dependent manner. Our ongoing studies are aimed at elucidating the potential correlation of gene expression levels of ID family members with the survival of NSCLC patients, using microarray datasets. Citation Format: Namrata Bora Singhal, Deepak Perumal, Srikumar Chellappan. Inhibitor of Differentiation/DNA binding (ID) proteins modulate the stem-like features of NSCLC cells by regulating the expression of Oct4, Sox2 and Nanog. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2655. doi:10.1158/1538-7445.AM2013-2655

Cigarette smoke induces methylation of the tumor suppressor gene NISCH

We have previously identified a putative tumor suppressor gene, NISCH, whose promoter is methylated in lung tumor tissue as well as in plasma obtained from lung cancer patients. NISCH was observed to be more frequently methylated in smoker lung cancer patients than in non-smoker lung cancer patients. Here, we investigated the effect of tobacco smoke exposure on methylation of the NISCH gene. We tested methylation of NISCH after oral keratinocytes were exposed to mainstream and side stream cigarette smoke extract in culture. Methylation of the promoter region of the NISCH gene was also evaluated in plasma obtained from lifetime non-smokers and light smokers (< 20 pack/year), with and without lung tumors, and heavy smokers (20+ pack/year) without disease. Promoter methylation of NISCH was tested by quantitative fluorogenic real-time PCR in all samples. Promoter methylation of NISCH occurred after exposure to mainstream tobacco smoke as well as to side stream tobacco smoke in normal oral keratinocyte cell lines. NISCH methylation was also detected in 68% of high-risk, heavy smokers without detectable tumors. Interestingly, in light smokers, NISCH methylation was present in 69% of patients with lung cancer and absent in those without disease. Our pilot study indicates that tobacco smoke induces methylation changes in the NISCH gene promoter before any detectable cancer. Methylation of the NISCH gene was also found in lung cancer patients’ plasma samples. After confirming these findings in longitudinally collected plasma samples from high-risk populations (such as heavy smokers), examining patients for hypermethylation of the NISCH gene may aid in identifying those who should undergo additional screening for lung cancer.

Human Papillomavirus Up-Regulates MMP-2 and MMP-9 Expression and Activity by Inducing Interleukin-8 in Lung Adenocarcinomas

Human papillomavirus (HPV) infection is associated with non-smoking female lung cancer. Our previous report demonstrated that HPV 16 promotes lung tumor cell progression by up-regulating interleukin-17 (IL-17). IL-17 and its downstream signaling mediator, interleukin-8 (IL-8), have been implicated to modulate a variety of pro-angiogenic factors and play important roles in tumor angiogenesis and metastasis. Accordingly, we hypothesized that HPV infection may potentiate tumorigenic and metastatic characteristics of the infected cells through IL-8. The goal of the present study was to determine whether HPV infection in lung adenocarcinoma cells can promote the expression of IL-8 and metalloproteinases (MMPs) to make the transformed cells equipped with angiogenic and metastatic characteristics. The expression of IL-8 and MMPs in HPV 16 E6-transfected H1299 cells was analyzed to examine the hypothesis. HPV 16 E6 up-regulates pro-angiogenic MMP-2 and MMP-9 through inducing IL-8 expression in lung cancer cells. The results indicate that, in addition to cell proliferation-related machinery, HPV infection promotes the expression and activities of angiogenic and metastatic molecules in lung adenocarcinoma cells. The cytokines induced by HPV infection may work together to confer the malignant and tumorigenic potentials on the infected cells by promoting machineries of growth, angiogenic and metastatic characteristics.

Human Papillomavirus Type 16/18 Oncoproteins: Potential Therapeutic Targets in Non-smoking Associated Lung Cancer

High-risk human papillomavirus (HPV) especially HPV-16 and HPV-18 types are speculated to be important risk factors in non-smoking associated lung cancer in Asia. Increasing evidence has demonstrated that HPV oncoproteins may contribute to lung tumorigenesis and cell transformation. Importantly, HPV 16/18 E6 and E7 oncoproteins can mediate expression of multiple target genes and proteins, such as p53/pRb, VEGF, HIF-1α, cIAP-2, and hTERT, and contribute to cell proliferation, angiogenesis and cell immortalization through different signaling pathways in lung cancer. This article provides an overview of experiment data on HPV-associated lung cancer, describes the main targets on which HPV E6/E7 oncoproteins act, and further discusses the potential signaling pathways in which HPV E6/E7 oncoproteins are involved. In addition, we also raise questions regarding existing problems with the study of HPV-associated lung cancer.

A Randomized Controlled Trial on the Efficacy of Thoracic CT Screening for Lung Cancer in Non-smokers and Smokers of &lt;30 Pack-years Aged 50-64 Years (JECS Study): Research Design

In order to assess the efficacy of lung cancer screening using low-dose thoracic computed tomography, compared with chest roentgenography, in people aged 50-64 years with a smoking history of <30 pack-years, a randomized controlled trial is being conducted in Japan. The screening methods are randomly assigned individually. The duration of this trial is 10 years. In the intervention arm, low-dose thoracic computed tomography is performed for each participant in the first and the sixth years. In the control arm, chest roentgenography is performed for each participant in the first year. The participants in both arms are also encouraged to receive routine lung cancer screening using chest roentgenography annually. The interpretation of radiological findings and the follow-up of undiagnosed nodules are to be carried out according to the guidelines published in Japan. The required sample size is calculated to be 17 500 subjects for each arm.

Study of miRNA Signatures as Biomarkers for Early Stage Nonsmoking Female Lung Cancer of Xuanwei County ofYunnan Province

Study of miRNA Signatures as Biomarkers for Early Stage Nonsmoking Female Lung Cancer of Xuanwei County ofYunnan Province

Functional Characterization of CLPTM1L as a Lung Cancer Risk Candidate Gene in the 5p15.33 Locus

Cleft Lip and Palate Transmembrane Protein 1-Like (CLPTM1L), resides in a region of chromosome 5 for which copy number gain has been found to be the most frequent genetic event in the early stages of non-small cell lung cancer (NSCLC). This locus has been found by multiple genome wide association studies to be associated with lung cancer in both smokers and non-smokers. CLPTM1L has been identified as an overexpressed protein in human ovarian tumor cell lines that are resistant to cisplatin, which is the only insight thus far into the function of CLPTM1L. Here we find CLPTM1L expression to be increased in lung adenocarcinomas compared to matched normal lung tissues and in lung tumor cell lines by mechanisms not exclusive to copy number gain. Upon loss of CLPTM1L accumulation in lung tumor cells, cisplatin and camptothecin induced apoptosis were increased in direct proportion to the level of CLPTM1L knockdown. Bcl-xL accumulation was significantly decreased upon loss of CLPTM1L. Expression of exogenous Bcl-xL abolished sensitization to apoptotic killing with CLPTM1L knockdown. These results demonstrate that CLPTM1L, an overexpressed protein in lung tumor cells, protects from genotoxic stress induced apoptosis through regulation of Bcl-xL. Thus, this study implicates anti-apoptotic CLPTM1L function as a potential mechanism of susceptibility to lung tumorigenesis and resistance to chemotherapy.

P1.11 Stage-Associated Difference in Microrna Expression in Lung Adenocarcinoma from Smokers and Non-Smokers

ABSTRACT Background To identify alterations in miRNA expression that occur in the early and late stages of lung cancer in smokers and non-smokers, we conducted miRNA profiling analysis. MiRNAs abnormally expressed in lung adenocarcinomas were compared in smokers vs. non-smokers as well as early stage vs. late stage disease. Materials and methods We collected 62 lung adenocarcinoma samples with paired non-neoplastic lung tissue from patients with no pre-operative therapy at Fox Chase Cancer Center and Methodist Hospital. Twenty-five patients had no history of tobacco smoking. The clinical stages were proportionally matched between smokers and non-smokers. MiRNA expression was profiled using the Human miRNA V2 Oligo Microarray Kit (Agilent Technologies, Alto, CA). The human miRNAs were background-subtracted, quantile-normalized in arrays, and log-2 transformed. The differences of mRNAs between tumor and normal tissue were examined using two-factor linear model. We assessed the local false discovery rates (FDRs) for all terms including the intercept using the Bum method (Pounds and Morris, 2003). Results We identified 63 miRNAs with FDR Table 1 . Conclusion Eighty-one percent of the altered miRNAs were observed in both smokers and non-smokers, which suggests a common epigenetic predisposition for lung adenocarcinoma development. Altered miRNAs expressed in early stage lung adenocarcinoma may be used as markers for the early detection of lung cancer. Table 1 . MiRNAs abnormally expressed in lung adenocarcinoma Patient characteristics miRNAs S/N/E/L 126, 130a, 135b, 141, 144, 145, 21, 21*, 200b, 210, 218, 30a, 30a*, 30c, 338-3p, 424, 451, 486-5p, 494, 497, 574-5p, 96, 99a S/N/E 200, 429 N/E/L 34c-5p N/L 135a*, 198 S, smoker; N, non-smoker; E, early stage; L, late stage.

CEA levels and EGFR mutations associated with patients in nonsmokers lung cancer.

e18038 Background: Background: As the non-smoking Asian patients with adenocarcinoma of the EGFR gene tend to have higher mutation rate, and serum CEA levels in patients with lung cancer, especially adenocarcinoma, high expression in many recent years, studies have also found that serum CEA levels in EGFR-changes before and after TKI therapy efficacy and treatment are closely related. However, whether serum CEA level and EGFR gene mutations is a correlation between two biomarkers. This study attempts to explore its relevance between EGFR gene mutations and analysis of serum CEA levels in non-smoking patients with lung cancer and it’s various clinical and pathological features. Methods: 84 cases of histologically confirmed non-smoking history in newly diagnosed lung cancer patients, respectively, serum CEA levels and histological detection of EGFR gene. According to the expression level of serum CEA patients were divided into high expression and did not express two groups were compared in patients with EGFR gene mutations. Results: 58/84 cases were found with activity EGFR gene mutations, the overall mutation rate was 69.0%, serum CEA levels high expression of EGFR gene mutation was significantly higher than non-expression group (serum CEA levels were &lt;5ng/ml, ≥ 5ng/ml &lt;20ng/ml, ≥ 20ng/ml patients with EGFR gene mutations histology were 63.2%, 70.8%, 81.8%). Conclusions: Non-smoking lung cancer patients with serum CEA levels and EGFR gene mutations was positively correlated.

New experimental data linking secondhand smoke exposure to lung cancer in nonsmokers

Secondhand smoke (SHS) exposure is a known risk factor for lung cancer development in lifelong nonsmokers; however, the mechanistic involvement of SHS in the genesis of this malignancy remains elusive. The present study is the first comprehensive investigation of SHS mutagenicity in vivo, in which we have established the mutagenic effects of SHS in transgenic Big Blue mice, and subsequently found correlations between our experimental findings and those obtained from our analysis of the largest database of mutations in human TP53, which is the most frequently mutated gene in human lung cancer. We demonstrate that whole-body SHS exposure of mice for 5 h/d, 5 d/wk for a duration of 2 or 4 mo elicits a significant mutagenic response in the lung, trachea, and bladder of exposed animals, as reflected by the elevation of background cII mutant frequency in the respective organs. The organ-specific mutagenicity of SHS is most pronounced in the lung and remains persistent both in the lung and bladder of SHS-exposed animals after a 1-mo recovery in clean air. The induced cII mutagenesis in the lung of SHS-exposed mice perfectly recapitulates our analysis of the TP53 mutations in human lung cancer in nonsmokers. Remarkably, the relative frequencies of all types of mutations in the TP53 gene of nonsmokers' lung tumors and in the cII transgene of lung cellular DNA from SHS-exposed mice are indistinguishable from one another. We provide the first verification of a mechanistic mode of action for SHS of relevance for carcinogenesis and the first experimental evidence linking SHS exposure to lung cancer in nonsmokers.

Smoking Cause Specific Lung Cancer—Evidence from Non-Smoking Lung Adenocarcinoma

Introduction: Smoking and non-smoking lung cancer have many differences in clinical feature. But those may be the result of interference due to differences in pathological type, as most smoking patients suffer squmous cell lung cancer and non-smokings tend to get adenocarcinoma. This study was conducted on the specific histological type-lung adenocarcinoma-to avoid histological bias and to reveal the true effect of smoking. Methods: A total of 2222 patients with lung adenocarcinoma confirmed by histological or cytological evidence were enrolled from January 1, 1999 to December 31, 2004. Differences in clinical features and prognosis between non-smoking and smoking patients were analyzed.Chisquare test was used for univariate comparisons. Univariate probability of survival was computed using Kaplan-Meier estimate and compared to using the log-rank test. Cox proportional hazards regression analysis was used to evaluate the risk of death. Results: There were 777 current smokers (34.96%), 197 former smokers (8.87%) and 1248 non-smoking patients (56.17%). 860 non-smoking patients (68.91%) were female, compared with 6.31% among current smokers and 4.06% among former smokers (p < 0.001). Non-smoking patients had an earlier age at diagnosis (p < 0.001) and a better response to chemotherapy (p < 0.001) compared to current smoking patients. Current smoking correlated with lower cell differentiation (p < 0.001) and worse prognosis (p = 0.0024). After multivariate analysis, smoking was identified as an independent negative prognostic factor (HR, 1.302; 95% CI, 1.011 - 1.6780, p = 0.041). No difference in prognosis was observed according to smoking conditions in smoking patients. Conclusions: Significent differences exist in clinical features and prognosis between non-smoking and smoking lung adenocarcinoma patients. There is a strong evidence that non-smoking lung adenocarcinoma should be regard as different disease.

Multiple Analytical Approaches Reveal Distinct Gene-Environment Interactions in Smokers and Non Smokers in Lung Cancer

Complex disease such as cancer results from interactions of multiple genetic and environmental factors. Studying these factors singularly cannot explain the underlying pathogenetic mechanism of the disease. Multi-analytical approach, including logistic regression (LR), classification and regression tree (CART) and multifactor dimensionality reduction (MDR), was applied in 188 lung cancer cases and 290 controls to explore high order interactions among xenobiotic metabolizing genes and environmental risk factors. Smoking was identified as the predominant risk factor by all three analytical approaches. Individually, CYP1A1*2A polymorphism was significantly associated with increased lung cancer risk (OR = 1.69;95%CI = 1.11–2.59,p = 0.01), whereas EPHX1 Tyr113His and SULT1A1 Arg213His conferred reduced risk (OR = 0.40;95%CI = 0.25–0.65,p<0.001 and OR = 0.51;95%CI = 0.33–0.78,p = 0.002 respectively). In smokers, EPHX1 Tyr113His and SULT1A1 Arg213His polymorphisms reduced the risk of lung cancer, whereas CYP1A1*2A, CYP1A1*2C and GSTP1 Ile105Val imparted increased risk in non-smokers only. While exploring non-linear interactions through CART analysis, smokers carrying the combination of EPHX1 113TC (Tyr/His), SULT1A1 213GG (Arg/Arg) or AA (His/His) and GSTM1 null genotypes showed the highest risk for lung cancer (OR = 3.73;95%CI = 1.33–10.55,p = 0.006), whereas combined effect of CYP1A1*2A 6235CC or TC, SULT1A1 213GG (Arg/Arg) and betel quid chewing showed maximum risk in non-smokers (OR = 2.93;95%CI = 1.15–7.51,p = 0.01). MDR analysis identified two distinct predictor models for the risk of lung cancer in smokers (tobacco chewing, EPHX1 Tyr113His, and SULT1A1 Arg213His) and non-smokers (CYP1A1*2A, GSTP1 Ile105Val and SULT1A1 Arg213His) with testing balance accuracy (TBA) of 0.6436 and 0.6677 respectively. Interaction entropy interpretations of MDR results showed non-additive interactions of tobacco chewing with SULT1A1 Arg213His and EPHX1 Tyr113His in smokers and SULT1A1 Arg213His with GSTP1 Ile105Val and CYP1A1*2C in nonsmokers. These results identified distinct gene-gene and gene environment interactions in smokers and non-smokers, which confirms the importance of multifactorial interaction in risk assessment of lung cancer.

Non-small Cell Lung Cancer in Nonsmokers

Non-small Cell Lung Cancer in Nonsmokers

Abstract A6: Urinary levels of volatile organic carcinogens and toxicant biomarkers in relation to lung cancer development in both smokers and nonsmokers: The Shanghai Cohort Study

Abstract Background: Benzene and ethylene oxide are considered carcinogenic to humans by International Agency for Research on Cancer based on experimental animal studies whereas acrolein and crotonaldehyde are considered weak carcinogens. They are present in cigarette smoke and other environmental sources. Epidemiological data linking them to lung cancer in humans have been lacking. Methods: A nested case-control study of lung cancer was conducted within the Shanghai Cohort Study, a population-based prospective cohort of 18,244 Chinese men aged 45–64 years at enrollment during 1986–1989. In addition to in-person interviews for information on use of tobacco and alcohol, usual diet, and medical history, each participant provided a 10-ml blood sample and one single void urine sample at baseline. Annual follow-ups to each surviving subject were conducted to identify incident cancer cases and death. The present study included 96 cases who never smoked and 343 cases who smoked cigarettes at baseline. One control for each case was randomly chosen among cohort participants. The control was matched to the index case by age (±2 years), date of urine collection (±1 month), neighborhood of residence, and smoking status. We quantified urinary mercapturic acid metabolites for benzene [S-phenyl mercapturic acid (SPMA)], ethylene oxide [2-hydroxyethyl mercapturic acid (HEMA)], acrolein [3-hydroxypropyl mercapturic acid (HPMA)], and crotonaldehyde [4-hydroxybut-2-yl mercapturic acid (HBMA)] for all study subjects. For current smokers, we also determined urinary levels of cotinine and its glucuronides (total cotinine), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol and its glucuronides (total NNAL), and r-1,t-2,3,c-4-tetrahydroxy-1,2,3,4-tetrahydrophenanthrene and its glucuronides (PheT), validated biomarkers of uptake and metabolism of nicotine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), and polycyclic aromatic hydrocarbons (PAH), respectively, for current smokers. The odds ratio (OR) and 95% confidence interval (CI) for lung cancer with urinary biomarkers were estimated using an unconditional logistic regression method. Results: Among current smokers, all measured mercapturic acid metabolites were statistically significantly higher in cases than controls. Compared with the lowest quartile, ORs (95% CIs) of lung cancer for highest quartile were 1.80 (1.14–2.85) for SPMA, 2.13 (1.34–3.37) for HEMA, 2.00 (1.25–3.20) for HPMA, and 1.95 (1.22–3.12) for HBMA (all P's for trend &amp;lt;0.01). Further adjustment for urinary total cotinine, total NNAL, and PheT significantly attenuated and resulted in a null association between all mercapturic acid metabolites and lung cancer risk (all P's for trend &amp;gt;0.50). Among never smokers, cases showed elevated levels of SPMA, but similar levels of HEMA, HPMA, and HBMA, compared with controls. OR for lung cancer was 2.11 (95% CI 1.05–4.23) for highest tertile of SPMA (P for trend = 0.026). There was no statistically significant association between urinary HEMA, HPMA or HBMA and lung cancer risk among never smokers. Conclusion: Urinary SPMA, a mercapturic acid metabolite for benzene, is statistically significant associated with lung cancer risk among never smokers whereas this positive association among current smokers could be largely explained by urinary biomarkers for nicotine, NNK and PAH, established risk factors for lung cancer for smokers in the present study population. Mercapturic acid metabolites for acrolein, crotonaldehyde, and ethylene oxide are not independent predictors for lung cancer for both smokers and nonsmokers. Citation Information: Cancer Prev Res 2011;4(10 Suppl):A6.

Aryl hydrocarbon receptor in association with RelA modulates IL-6 expression in non-smoking lung cancer

Aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that is activated by cigarette smoke. Previously, we demonstrated that AhR is overexpressed in lung adenocarcinomas (ADs). In this study we observed that AhR expression is significantly correlated with nuclear RelA (a nuclear factor-κB (NFκB) subunit) and cytosolic interleukin-6 (IL-6) in 200 non-small cell lung cancer patients, especially among never smokers. Overexpression of AhR increased IL-6 expression in H1355 cells and immortalized human bronchial epithelial cells BEAS-2B. As NFκB inhibitor and knockdown RelA expression greatly reduced constitutive AhR-induced IL-6 expression, we hypothesized that AhR expression, in the absence of exogenous ligand, is able to modulate NFκB activity and subsequently upregulate IL-6 expression, thus promoting the development of lung AD. Specifically, AhR overexpression significantly increased NFκB activity, whereas interference with AhR expression significantly reduced NFκB activity and IL-6 expression in H1355 cells. We demonstrated that AhR associates with RelA in the cytosol and nucleus of human lung cells. Furthermore, AhR overexpression enhanced nuclear localization of AhR and RelA, and increased the association of AhR-RelA with the NFκB response element of the IL-6 promoter. However, p50 was not involved. Our results indicate that AhR, without exposure to a ligand, associates with RelA, which then positively modulates NFκB activity and then upregulates IL-6 expression in human lung cells. Thus we have identified a new mechanism for lung tumorigenesis in non-smokers.