Mouse pulmonary adenoma susceptibility 1 locus is an expression QTL modulating Kras-4A.

Pulmonary adenoma susceptibility 1 (Pas1) is the major locus responsible for lung tumor susceptibility in mice; among the six genes mapping in this locus, Kras is considered the best candidate for Pas1 function although how it determines tumor susceptibility remains unknown. In an (A/J × C57BL/6)F4 intercross population treated with urethane to induce lung tumors, Pas1 not only modulated tumor susceptibility (LOD score = 48, 69% of phenotypic variance explained) but also acted, in lung tumor tissue, as an expression quantitative trait locus (QTL) for Kras-4A, one of two alternatively spliced Kras transcripts, but not Kras-4B. Additionally, Kras-4A showed differential allelic expression in lung tumor tissue of (A/J × C57BL/6)F4 heterozygous mice, with significantly higher expression from the A/J-derived allele; these results suggest that cis-acting elements control Kras-4A expression. In normal lung tissue from untreated mice of the same cross, Kras-4A levels were also highly linked to the Pas1 locus (LOD score = 23.2, 62% of phenotypic variance explained) and preferentially generated from the A/J-derived allele, indicating that Pas1 is an expression QTL in normal lung tissue as well. Overall, the present findings shed new light on the genetic mechanism by which Pas1 modulates the susceptibility to lung tumorigenesis, through the fine control of Kras isoform levels.

Germline polymorphisms and survival of lung adenocarcinoma patients: a genome-wide study in two European patient series.

In lung cancer, the survival of patients with the same clinical stage varies widely for unknown reasons. In this two-phase study, we examined the hypothesis that germline variations influence the survival of patients with lung adenocarcinoma. First, we analyzed existing genotype and clinical data from 289 UK-resident patients with lung adenocarcinoma, identifying 86 single nucleotide polymorphisms (SNPs) that associated with survival (p < 0.01). We then genotyped these candidate SNPs in a validation series of 748 patients from Italy that resulted genetically compatible with the UK series based on principal component analysis. In a Cox proportional hazard model adjusted for age, sex and clinical stage, four SNPs were confirmed on the basis of their having a hazard ratio (HR) indicating the same direction of effect in the two series and p < 0.05. The strongest association was provided by rs2107561, an intronic SNP of PTPRG, protein tyrosine phosphatase, receptor type, G; the C allele was associated with poorer survival in both patient series (pooled analysis loge HR = 0.31; 95% CI: 0.15-0.46, p = 8.5 × 10(-5) ). PTPRG mRNA levels in 43 samples of lung adenocarcinoma were 40% of those observed in noninvolved lung tissue from the same patients. PTPRG overexpression significantly inhibited the clonogenicity of A549 lung carcinoma cells and the anchorage-independent growth of the NCI-H460 large cell lung cancer line. These four germline variants represent promising candidates that, with further study, may help predict clinical outcome. In addition, the PTPRG locus may have a role in tumor progression.

Unique microRNA-profiles in EGFR-mutated lung adenocarcinomas.

The findings of mutations and the development of targeted therapies have improved lung cancer management. Still, the prognosis remains poor, and we need to know more about the genetic and epigenetic alterations in lung cancer. MicroRNAs are involved in crucial biological processes like carcinogenesis by regulating gene expression at the post-transcriptional level. In this project, we have studied the microRNA expression of lung adenocarcinomas and corresponding normal lung tissue and correlated the expression with clinical data and EGFR- and KRAS-mutational status. Agilent microarrays have been used, examining microRNA expression in 154 surgically resected lung adenocarcinomas and 20 corresponding normal lung tissue samples. Findings were confirmed by RT-qPCR in the same cohort and in an independent cohort of 103 lung cancer patients. EGFR and KRAS mutation analyses were also performed. 129 microRNAs were significantly differentially expressed in lung adenocarcinomas compared with normal lung tissue, and 17 microRNAs were differentially expressed between EGFR-mutated and EGFR wildtype tumors. We identified microRNAs associated with time to progression. We have identified several aberrantly expressed microRNAs that discriminate lung adenocarcinomas from normal lung tissue, and hence may be potential biomarkers for early detection. We have found microRNAs that are differentially expressed between EGFR-mutated and EGFR wildtype lung adenocarcinomas, suggesting that microRNAs can be used as molecular biomarkers in classification. We hypothesize that microRNA expression can be used as biomarkers for clinical course.

Gene expression signature of non-involved lung tissue associated with survival in lung adenocarcinoma patients.

Lung adenocarcinoma patients of similar clinical stage and undergoing the same treatments often have marked interindividual variations in prognosis. These clinical discrepancies may be due to the genetic background modulating an individual's predisposition to fighting cancer. Herein, we hypothesized that the lung microenvironment, as reflected by its expression profile, may affect lung adenocarcinoma patients' survival. The transcriptome of non-involved lung tissue, excised from a discovery series of 204 lung adenocarcinoma patients, was evaluated using whole-genome expression microarrays (with probes corresponding to 28 688 well-annotated coding sequences). Genes associated with survival status at 60 months were identified by Cox regression analysis (adjusted for gender, age and clinical stage) and retested in a validation series of 78 additional cases. RNA-Seq analysis from non-involved lung tissue of 12 patients was performed to characterize the different isoforms of candidate genes. Ten genes for which the loge-transformed hazard ratios expressed the same direction of effect in the discovery (P < 1.0 × 10(-3)) and validation series comprised the gene expression signature associated with survival: CNTNAP1, PKNOX1, FAM156A, FRMD8, GALNTL1, TXNDC12, SNTB1, PPP3R1, SNX10 and SERPINH1. RNA sequencing highlighted the complex expression pattern of these genes in non-involved lung tissue from different patients and permitted the detection of a read-through gene fusion between PPP3R1 and the flanking gene (CNRIP1) as well as a novel isoform of CNTNAP1. Our findings support the hypothesis that individual genetic characteristics, evidenced by the expression pattern of non-involved tissue, influence the outcome of lung adenocarcinoma patients.

Genetic control of renal tumorigenesis by the mouse Rtm1 locus.

BACKGROUND: The genetic basis of susceptibility to renal tumorigenesis has not yet been established in mouse strains. Mouse lines derived by bidirectional phenotypic selection on the basis of their maximal (AIRmax) or minimal (AIRmin) acute inflammatory responsiveness differ widely in susceptibility to spontaneous and urethane-induced renal tumorigenesis. To map the functional loci modulating renal tumor susceptibility in these mice, we carried out a genome-wide genetic linkage study, using SNP arrays, in an (AIRmax x AIRmin)F2 intercross population treated with a single urethane dose at 1 week of age and phenotyped for renal tumors at 35 weeks of age. RESULTS: AIRmax mice did not develop renal tumors spontaneously nor in response to urethane, whereas in AIRmin mice renal tumors formed spontaneously (in 52% of animals) and after urethane induction (89%). The tumors had a papillary morphology and were positive for alpha-methylacyl-CoA racemase and negative for CD10. By analysis of 879 informative SNPs in 662 mice, we mapped a single quantitative trait locus modulating the incidence of renal tumors in the (AIRmax x AIRmin)F2 intercross population. This locus, which we named Renal tumor modifier QTL 1 (Rtm1), mapped to chromosome 17 at 23.4 Mb (LOD score = 15.8), with SNPs rs3696835 and rs3719497 flanking the LOD score peak. The A allele of rs3719497 from AIRmin mice was associated with a 2.5-fold increased odds ratio for renal tumor development. The LOD score peak included the Tuberous sclerosis 2 (Tsc2) gene which has already been implicated in kidney disease: loss of function by germline retroviral insertion is associated with spontaneous renal tumorigenesis in the Eker rat, and heterozygous-null Tsc2(+/-) mice develop renal cystadenomas. CONCLUSIONS: We mapped Rtm1 as a single major locus modulating renal tumorigenesis in a murine intercross population. Thus, the AIR mouse lines can be considered a new genetic model for studying the role of germline and somatic molecular alterations in kidney neoplastic disease.

Beyond genome-wide association studies: genetic heterogeneity and individual predisposition to cancer.

Genome-wide association studies (GWAS) using population-based designs have identified many genetic loci associated with risk of a range of complex diseases including cancer; however, each locus exerts a very small effect and most heritability remains unexplained. Family-based pedigree studies have also suggested tentative loci linked to increased cancer risk, often characterized by pedigree-specificity. However, comparison between the results of population- and family-based studies shows little concordance. Explanations for this unidentified genetic 'dark matter' of cancer include phenotype ascertainment issues, limited power, gene-gene and gene-environment interactions, population heterogeneity, parent-of-origin-specific effects, and rare and unexplored variants. Many of these reasons converge towards the concept of genetic heterogeneity that might implicate hundreds of genetic variants in regulating cancer risk. Dissecting the dark matter is a challenging task. Further insights can be gained from both population association and pedigree studies.

Association of lung adenocarcinoma clinical stage with gene expression pattern in noninvolved lung tissue.

Associations between clinical outcome of cancer patients and the gene expression signature in primary tumors at time of diagnosis have been reported. To test whether gene expression patterns in noninvolved lung tissue might correlate with clinical stage in lung adenocarcinoma (ADCA) patients, we compared the transcriptome of noninvolved lung samples from 60 ADCA smoker patients of clinical stage I versus 60 patients with stage>I. Quantitative PCR of 10 genes with the most significant differential expression confirmed the statistical association with clinical stage in eight genes, six of which were downregulated in high-stage patients. Five of these six genes were also downregulated in lung ADCA tissue as compared to noninvolved tissue. Studies in vitro indicated that four of the genes (SLC14A1, SMAD6, TMEM100 and TXNIP) inhibited colony formation of lung cancer cell lines transfected to overexpress the genes, suggesting their potential tumor-suppressor activity. Our findings suggest that individual variations in the transcriptional profile of noninvolved lung tissue may reflect the lung ADCA patient's predisposition to tumor aggressiveness.

Testing of human papillomavirus in lung cancer and non-tumor lung tissue.

BACKGROUND: Risk factors for lung cancer, such as cigarette smoking, environmental pollution, asbestos, and genetic determinants, are well-known, whereas involvement of the human papillomavirus (HPV) is still unclear. METHODS: We examined a series of 100 lung cancer patients from Italy and the UK for the presence of HPV DNA in both lung tumor specimens and adjacent non-tumoral specimens from the same patients. Thirty-five of the most clinically relevant HPV types were assayed using PCR amplification of the highly conserved L1 region of the viral genome followed by hybridization with specific probes. RESULTS: No HPV was detected in tumor specimens nor in normal lung tissue of any patient. CONCLUSIONS: These data indicate that, in this Western series, HPV is not associated with the risk of lung cancer. Our findings will help refine estimates of lung cancer risk in patients affected by a common viral infection involved in other types of human cancer.

Genetic control of IL-1 beta production and inflammatory response by the mouse Irm1 locus.

Genome-wide linkage analysis using single nucleotide polymorphism arrays was carried out in pedigrees of mice differing in the extent of acute inflammatory response (AIRmax or AIRmin). The AIR phenotype was determined by quantifying the number of infiltrating cells in the 24-h exudate induced by Biogel P-100 s.c. injection and by ex vivo IL-1beta production by leukocytes stimulated with LPS and ATP. We mapped the major inflammatory response modulator 1 locus on chromosome 7, at the 1-logarithm of odds (LOD) confidence interval from 116.75 to 139.75 Mb, linked to the number of infiltrating cells (LOD = 3.61) through the production of IL-1beta (LOD = 9.35). Of several interesting candidate genes mapping to the inflammatory response modulator 1 locus, 28 of these were differentially expressed in the bone marrow of AIRmax and AIRmin mice. These findings represent a step toward the identification of the genes underlying this complex phenotype.

Mouse genome-wide association mapping needs linkage analysis to avoid false-positive Loci.

We carried out genome-wide association (GWA) studies in inbred mouse strains characterized for their lung tumor susceptibility phenotypes (spontaneous or urethane-induced) with panels of 12,959 (13K) or 138,793 (140K) single-nucleotide polymorphisms (SNPs). Above the statistical thresholds, we detected only SNP rs3681853 on Chromosome 5, two SNPs in the pulmonary adenoma susceptibility 1 (Pas1) locus, and SNP rs4174648 on Chromosome 16 for spontaneous tumor incidence, urethane-induced tumor incidence, and urethane-induced tumor multiplicity, respectively, with the 13K SNP panel, but only the Pas1 locus with the 140K SNP panel. Haplotype analysis carried out in the latter panel detected four additional loci. Loci reported in previous GWA studies failed to replicate. Genome-wide genetic linkage analysis in urethane-treated (BALB/cxC3H/He)F2, (BALB/cxSWR/J)F2, and (A/JxC3H/He)F2 mice showed that Pas1, but none of the other loci detected previously or herein by GWA, had a significant effect. The Lasc1 gene, identified by GWA as a functional element (Nat. Genet., 38:888-95, 2006), showed no genetic effects in the two independent intercross mouse populations containing both alleles, nor was it expressed in mouse normal lung or lung tumors. Our results indicate that GWA studies in mouse inbred strains can suffer a high rate of false-positive results and that such an approach should be used in conjunction with classical linkage mapping in genetic crosses.

A 5'-region polymorphism modulates promoter activity of the tumor suppressor gene MFSD2A.

BACKGROUND: The MFSD2A gene maps within a linkage disequilibrium block containing the MYCL1-EcoRI polymorphism associated with prognosis and survival in lung cancer patients. Survival discrepancies between Asians and Caucasians point to ethnic differences in allelic frequencies of the functional genetic variations. RESULTS: Analysis of three single-nucleotide polymorphisms (SNPs) mapping in the MFSD2A 5'-regulatory region using a luciferase reporter system showed that SNP rs12072037, in linkage disequilibrium with the MYCL1-EcoRI polymorphism and polymorphic in Asians but not in Caucasians, modulated transcriptional activity of the MFSD2A promoter in cell lines expressing AHR and ARNT transcription factors, which potentially bind to the SNP site. CONCLUSION: SNP rs12072037 modulates MFSD2A promoter activity and thus might affect MFSD2A levels in normal lung and in lung tumors, representing a candidate ethnically specific genetic factor underlying the association between the MYCL1 locus and lung cancer patients' survival.

Nicotine dependence may link the 15q25 locus to lung cancer risk.

The nicotinic 15q25 locus has been implicated in lung cancer risk, with an odds ratio of approximately 1.3. The same locus is associated with nicotine dependence due to cigarette smoking and with smoking-associated chronic obstructive pulmonary disease, which is a risk factor for lung cancer. Our meta-analysis of reported studies shows that this locus was not associated with lung cancer risk in >1000 never-smoker cases and >1800 controls. Review of exposure-response data for lung cancer risk showed that less than a half-cigarette per day may confer the same risk of lung cancer as that conferred by the 15q25 locus. Given the lack of effect in never-smokers and the known common and variable underreporting of smoking habit in studies on smoking-associated diseases, we cannot exclude that the association between the 15q25 locus and lung cancer risk is indirect, deriving from association of the same locus with smoking habit. Since nicotine is not carcinogenic, available data do not provide plausibility of the association between the nicotinic 15q25 locus and lung cancer pathogenesis. Thus, a direct link between the 15q25 locus and lung cancer risk has yet to be established.

Genome-wide association study in discordant sibships identifies multiple inherited susceptibility alleles linked to lung cancer.

We analyzed a series of young (median age = 52 years) non-smoker lung cancer patients and their unaffected siblings as controls, using a genome-wide 620 901 single-nucleotide polymorphism (SNP) array analysis and a case-control DNA pooling approach. We identified 82 putatively associated SNPs that were retested by individual genotyping followed by use of the sib transmission disequilibrium test, pointing to 36 SNPs associated with lung cancer risk in the discordant sibs series. Analysis of these 36 SNPs in a polygenic model characterized by additive and interchangeable effects of rare alleles revealed a highly statistically significant dosage-dependent association between risk allele carrier status and proportion of cancer cases. Replication of the same 36 SNPs in a population-based series confirmed the association with lung cancer for three SNPs, suggesting that phenocopies and genetic heterogeneity can play a major role in the complex genetics of lung cancer risk in the general population.

Transcription deregulation at the 15q25 locus in association with lung adenocarcinoma risk.

PURPOSE: We characterized the candidacy of the six candidate genes mapping in the chromosome 15q25 locus, which was previously reported as associated with lung cancer risk, and confirmed the locus association with lung cancer risk in an Italian population of lung adenocarcinoma patients and controls. EXPERIMENTAL DESIGN: We did a quantitative analysis of mRNA levels of IREB2 (iron-responsive element-binding protein 2), LOC123688, PMSA4 [proteasome (prosome, macropain) subunit alpha type 4], CHRNB4 (cholinergic receptor nicotinic beta 4), CHRNA3 (cholinergic receptor nicotinic alpha 3), and CHRNA5 (cholinergic receptor nicotinic alpha 5) genes in paired normal lung and lung adenocarcinoma tissue, and an immunohistochemical localization of CHRNA3- and CHRNA5-encoded proteins. We also examined the association of CHRNA5 D398N polymorphism with lung cancer risk and with CHRNA5 mRNA levels in the normal lung. RESULTS: Expression analysis of the six candidate genes mapping in the lung cancer risk-associated chromosome 15q25 locus revealed a 30-fold up-regulation of the gene encoding the CHRNA5 subunit and a 2-fold down-regulation of the CHRNA3 subunit in lung adenocarcinoma as compared with the normal lung. The expression of the four other candidate genes resulted either unchanged or absent. The carrier status of the 398N allele at the D398N polymorphism of the CHRNA5 gene was associated with lung adenocarcinoma risk (odds ratio, 1.5; 95% confidence interval, 1.2-2.0) in a population-based series of lung adenocarcinoma patients (n=467) and healthy controls (n=739). Analysis of a family-based series of nonsmoker lung cancer cases (n=80) and healthy sib controls (n=80) indicated a similar trend. In addition, the same D398N variation correlated with CHRNA5 mRNA levels in normal lung of adenocarcinoma patients. CONCLUSIONS: Our results point to the candidacy of the CHRNA5 gene for the 15q25 locus.

Identification of genetic polymorphisms modulating nausea and vomiting in two series of opioid-treated cancer patients.

Nausea and vomiting are often associated with opioid analgesia in cancer patients; however, only a subset of patients develop such side effects. Here, we tested the hypothesis that the occurrence of nausea and vomiting is modulated by the genetic background of the patients. Whole exome sequencing of DNA pools from patients with either low (n = 937) or high (n = 557) nausea and vomiting intensity, recruited in the European Pharmacogenetic Opioid Study, revealed a preliminary association of 53 polymorphisms. PCR-based genotyping of 45 of these polymorphisms in the individual patients of the same series confirmed the association for six SNPs in AIM1L, CLCC1, MUC16, PDE3A, POM121L2, and ZNF165 genes. Genotyping of the same 45 polymorphisms in 264 patients of the Italian CERP study, also treated with opioids for cancer pain, instead confirmed the association for two SNPs in ZNF568 and PDE3A genes. Only one SNP, rs12305038 in PDE3A, was confirmed in both series, although with opposite effects of the minor allele on the investigated phenotype. Overall, our findings suggest that genetic factors are indeed associated with nausea and vomiting in opioid-treated cancer patients, but the role of individual polymorphisms may be weak.

Aryl hydrocarbon receptor polymorphism modulates DMBA-induced inflammation and carcinogenesis in phenotypically selected mice.

We tested the role of aryl hydrocarbon receptor (Ahr) gene polymorphism in the inflammatory response and in skin and lung tumorigenesis in 2 lines of mice phenotypically selected for maximum or minimum acute inflammatory reaction (AIRmax and AIRmin, respectively). Following 7,12-dimethylbenz[a]anthracene (DMBA) treatment, AIRmin but not AIRmax mice showed early skin reactions and eventually developed malignant skin tumors and lung adenocarcinomas. In skin tissue, transcript levels of IL1beta, Tnf, Il6, Tgfbeta1 and Cyp1b1 genes were upregulated in AIRmin but not AIRmax mice, consistent with the inflammatory responses to the carcinogen. These findings appeared to be related to the homozygosity status of the Ahr functional A375V polymorphism, which influences the binding capability of the receptor for DMBA: the 375A allele, encoding the high-affinity ligand-binding receptor (Ahr(b1)), segregated in AIRmin mice, whereas AIRmax mice carried the 375V, corresponding to the low-affinity binding receptor (Ahr(d)), to DMBA. The differential segregation of Ahr functional Ahr(d)versus Ahr(b1) alleles in AIRmax and AIRmin suggests a role for the Ahr gene in the control of inflammatory responsiveness and tumor development of these mouse lines.

FGFR4 Gly388Arg polymorphism may affect the clinical stage of patients with lung cancer by modulating the transcriptional profile of normal lung.

The association of the fibroblast growth factor receptor 4 (FGFR4) Gly388Arg polymorphism with clinical stage and overall survival in a series of 541 Italian lung adenocarcinoma (ADCA) patients indicated a significantly decreased survival in patients carrying the rare Arg388 allele as compared to that in Gly/Gly homozygous patients [hazard ratio (HR) = 1.5; 95% confidence interval (CI) 1.1-1.9], with the decrease related to the association of the same polymorphism with clinical stage (HR = 1.8, 95% CI 1.3-2.6). By contrast, no significant association was detected in small series of either Norwegian lung ADCA patients or Italian lung squamous cell carcinoma (SQCC) patients. Single nucleotide polymorphisms of known FGFR4 ligands expressed in lung (FGF9, FGF18 and FGF19) were not associated with clinical stage or survival and showed no interaction with FGFR4. Analysis of gene expression profile in normal lungs according to FGFR4 genotype indicated a specific transcript pattern associated with the allele carrier status, suggesting a functional role for the FGFR4 polymorphism already detectable in normal lung. These findings confirm the significant association of the FGFR4 Gly388Arg polymorphism with clinical stage and overall survival in an Italian lung ADCA population and demonstrate a FGFR4 genotype-dependent transcriptional profile present in normal lung tissue.

Genetic control of resistance to hepatocarcinogenesis by the mouse Hpcr3 locus.

UNLABELLED: The genome of the BALB/c mouse strain provides alleles that dominantly inhibit hepatocellular tumor development in F1 crosses with the highly hepatocarcinogenesis-susceptible C3H/He strain. Genome-wide linkage analysis using a 1536-single-nucleotide polymorphism array in a (C3H/He x BALB/c)F2 intercross population treated with urethane to induce hepatocellular tumor development revealed a locus with a major role in the resistance to hepatocarcinogenesis. This locus, designated hepatocarcinogen resistance 3 (Hpcr3) and mapping to central chromosome 15, showed a linkage at LOD score = 16.52 and accounted for 40% of the phenotypical variance. The BALB/c-derived allele at Hpcr3 reduced tumor-occupied area of the liver up to 25-fold, in a semidominant way. Additional minor loci were mapped to chromosomes 1, 10, and 18. A gene expression profile of normal adult mouse liver showed a significant association with susceptibility of BALB/c, C3H/He, and F1 mice to hepatocarcinogenesis and identified the genes expressed in the Hpcr3 locus region; moreover, this analysis implicated the E2F1 pathway in the modulation of the phenotype susceptibility to hepatocarcinogenesis. CONCLUSION: These findings, indicating the complex genetics of dominant resistance to hepatocarcinogenesis, represent a step toward the identification of the genes underlying this phenotype.

A polygenic model with common variants may predict lung adenocarcinoma risk in humans.

Genome-wide screening for genetic loci associated with risk of lung adenocarcinoma (ADCA) was carried out in pooled DNA using the Illumina 300K single-nucleotide polymorphism (SNP) array, in a joint analysis of 2 Italian case-control series matched by age, gender and smoking habit. The rare allele carrier status of 8 SNPs was associated with a decreased lung ADCA risk [odds ratios (OR): 0.6-0.8]. In a polygenic model characterized by additive and interchangeable effects, individuals carrying 2 to 6 rare alleles at these 8 SNPs showed a significant trend toward a decreased risk of lung ADCA (up to OR of 0.3). These results suggest the relevance of a polygenic model in the modulation of individual risk of lung ADCA in the general population.

Genome-wide single nucleotide polymorphism analysis of lung cancer risk detects the KLF6 gene.

A genome-wide association analysis using the Affymetrix 100K SNP array was carried out in a case-control study of lung cancer. Allele frequencies were estimated initially in DNA pools. Significant differences in allele frequency detected in the SNP array analysis were first tested in the same DNA pools by pyrosequencing and then by individual genotyping. DNA pooling analysis identified rs10508266 SNP, located approximately 12.5kb from the 5'-end of the KLF6 gene, as a marker showing significant association with lung cancer risk. Since the SNP was in significant linkage disequilibrium with the KLF6 gene region, we analyzed an Italian population of 338 lung adenocarcinoma cases and 335 controls for the possible role of the reported functional rs3750861 SNP, located 15.6kb from the rs10508266 SNP. The rs3750861 affects expression of KLF6 splicing variants in prostate cancer and we found that its rare allele is associated with reduced lung cancer risk (odds ratio, 0.5; 95% CI, 0.3-0.8). A Norwegian replication series of 265 non small cell lung cancer cases, and 356 controls, however, did not confirm the association. In light of the reported functional involvement of the KLF6 gene in lung cancer and in other cancer types and to the functional nature of the rs3750861 SNP, our results suggest a potential involvement of KLF6 polymorphisms in lung cancer risk, although additional studies in large series are needed to confirm our findings and to elucidate the mechanism by which the KLF6 SNPs influence lung cancer risk.