Abstract Background: Recent genome-wide association studies (GWAS) have identified 28 susceptibility loci for Lung cancer (LC), 32 loci for smoking behavior, 10 loci for chronic obstructive pulmonary disease (COPD), 63 loci for pulmonary function and related phenotypes, totaling 107 GWAS susceptibility loci (as of November 2014). Given the common variants that have been found to be associated with LC in GWAS, targeted-region exome sequencing provides a cost-effective approach for further investigation of high-priority regions of the genome and has the great potential to identify rare causal variants in GWAS loci. Patients and Methods: Using an extreme phenotype approach, we selected 48 sporadic LC patients reporting heavy smoking histories with the presence of severe COPD in whom environmental factors are considered overwhelming, and 54 familial LC cases from families with at least three first-degree relatives with LC who are likely enriched for genomic signal, to search for the disease-causing rare mutations within the target 107 GWAS loci using exome sequencing data. Results: By focusing on exome profiles of these target 107 loci, we identified two disease-causing rare mutations on 6p21.32 TNXB p. Arg504His and 10q25.1 CCDC147 p.Arg696Cys. The homozygous Arg504His mutation presented in four familial and one sporadic LC cases. Notably, the minor allele frequency (MAF) of this variant in Caucasians from 1000 Genomes is very rare (<0.001). The heterozygous CCDC147 Arg696Cys variant were identified in two familial cases and one sporadic case. The MAF for this variant in the Caucasians from 1000 Genomes is 0.004. Both deleterious changes lead to truncation of the putative proteins, which disrupts the predicted domain and alters the cellular localization. We also observed several other suggestive rare mutations on G7C, TNS1, DBH1, and CHRNA5. Conclusion: Our target exome sequencing results demonstrate novel highly disruptive LC risk-conferring TNXB and CCDC147 mutations. Since the rare variants have appreciable effects on disease risk prediction, families and patients may warrant screening for mutations in TNXB and CCDC147 (if validated) to assess their potential LC risk. Citation Format: Yanhong Liu, Farrah Kheradmand, Michael Scheurer, Caleb Davis, David Wheeler, Edwin Silverman, Shete Sanjay, Spiridon Tsavachidis, Georgina Armstrong, Elena Kupert, Marshall Anderson, Yafang Li, Claudio Pikielny, Joan E. Bailey-Wilson, Ming You, Colette Gaba, Mariza DeAndrade, Diptasri Mandal, Claire Simpson, Susan Pinney, Christopher Amos, Margaret Spitz. Target exome sequencing for disease-causing rare mutations in familial and sporadic lung cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4600. doi:10.1158/1538-7445.AM2015-4600
Abstract 2757: Evaluation of EYA4 as a candidate risk locus in familial lung cancer families linked to 6q
Abstract Recently, Wilson et al. (doi:10.1038/onc.2013.396) found that EYA4 was frequently inactivated biallelically in sporadic lung cancer, displays tumor suppressor gene-like properties and affects DNA repair, and that 5 of 17 common SNPs in this 0.3Mb region showed nominal association to familial lung cancer (FLC, p<0.05) although these associations are not genome-wide significant after correction for multiple testing.. However, this is an interesting candidate gene for FLC risk because it is located on chromosome 6q in a region where we previously showed evidence of linkage to FLC (PMID: 15272417, 20215501). Here, we sequenced 75 individuals from our 9 most strongly 6q-linked families, using Illumina technology and a custom Agilent kit to capture 37Mb of chromosome 6 from 130Mb to 167Mb. We closely examined a region around EYA4, between 133Mb and 135Mb. This region contains a number of other genes in addition to EYA4, including the Vanin cluster; ribosomal protein S12; the tumor suppressor gene TCF21 and its antisense RNA TARID which directs methylation and activation of TCF21; solute carriers SLC18B1 and SLC2A12 and the serum/glucocorticoid regulated kinase SGK1. To detect sharing of variants among affecteds in each family while allowing for phenocopies, singlepoint affected-only linkage analysis was performed on lung cancer affection status for all sequence variants using the Elston-Stewart algorithm implemented in the R package paramlink assuming penetrance of 0.01, 0.1 and 0.1 for dd/Dd/DD and a disease allele (D) frequency of 0.01, at a recombination fraction (theta) of 0. The highest total LOD score (summed over all 9 families) in the entire 37Mb targeted region was not near EYA4. In only one family was there any variant in EYA4 that appeared on the linked haplotype with close to the highest family-specific LOD score: Family 30 had a LOD of 0.6514 at several EYA4 variants (max LOD across region 0.6519). However, many variants across the region had similar LODs. In the remaining families, all EYA4 variants had LODs much lower than the maximum family-specific LOD score in the region. Thus, EYA4 variants are unlikely to explain our 6q linkage peak in these 6q-linked families. The second highest total LOD score for the entire 37Mb targeted region was found near EYA4 at 133.9Mb (LOD = 3.82), in the middle of the TARID antisense RNA gene. This variant appears to be entirely novel, as it is not present in any of the online variant databases, such as NHLBI's ESP or 1000 Genomes. In two families, the family LOD score at this locus was at or close to the highest in the region: in Family 44 the LOD score was 1.206 (max LOD across entire region 1.207) and in Family 35 the LOD score was 0.3958 (max LOD across region 0.3959). Therefore this variant in the TARID antisense RNA is a candidate in some of our families most strongly linked to chromosome 6q. Citation Format: Joan E. Bailey-Wilson, Claire L. Simpson, Susan M. Pinney, Mariza de Andrade, Colette Gaba, Ping Yang, Ming You, Elena Y. Kupert, Ann G. Schwartz, Diptasri Mandal, Christopher I. Amos, Marshall W. Anderson. Evaluation of EYA4 as a candidate risk locus in familial lung cancer families linked to 6q. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2757. doi:10.1158/1538-7445.AM2015-2757
A Second Genetic Variant on Chromosome 15q24-25.1 Associates with Lung Cancer
Abstract Purpose: We have previously mapped a major susceptibility locus influencing familial lung cancer risk to chromosome 6q23-25. However, the causal gene at this locus remains undetermined. In this study, we further refined this locus to identify a single candidate gene, by fine mapping using microsatellite markers and association studies using high-density single nucleotide polymorphisms (SNP). Experimental Design: Six multigenerational families with five or more affected members were chosen for fine-mapping the 6q linkage region using microsatellite markers. For association mapping, we genotyped 24 6q-linked cases and 72 unrelated noncancer controls from the Genetic Epidemiology of Lung Cancer Consortium resources using the Affymetrix 500K chipset. Significant associations were validated in two independent familial lung cancer populations: 226 familial lung cases and 313 controls from the Genetic Epidemiology of Lung Cancer Consortium, and 154 familial cases and 325 controls from Mayo Clinic. Each familial case was chosen from one high-risk lung cancer family that has three or more affected members. Results: A region-wide scan across 6q23-25 found significant association between lung cancer susceptibility and three single nucleotide polymorphisms in the first intron of the RGS17 gene. This association was further confirmed in two independent familial lung cancer populations. By quantitative real-time PCR analysis of matched tumor and normal human tissues, we found that RGS17 transcript accumulation is highly and consistently increased in sporadic lung cancers. Human lung tumor cell proliferation and tumorigenesis in nude mice are inhibited upon knockdown of RGS17 levels. Conclusion: RGS17 is a major candidate for the familial lung cancer susceptibility locus on chromosome 6q23-25.
EGFR-T790M Is a Rare Lung Cancer Susceptibility Allele with Enhanced Kinase Activity
Abstract The use of tyrosine kinase inhibitors (TKI) has yielded great success in treatment of lung adenocarcinomas. However, patients who develop resistance to TKI treatment often acquire a somatic resistance mutation (T790M) located in the catalytic cleft of the epidermal growth factor receptor (EGFR) enzyme. Recently, a report describing EGFR-T790M as a germ-line mutation suggested that this mutation may be associated with inherited susceptibility to lung cancer. Contrary to previous reports, our analysis indicates that the T790M mutation confers increased Y992 and Y1068 phosphorylation levels. In a human bronchial epithelial cell line, overexpression of EGFR-T790M displayed a growth advantage over wild-type (WT) EGFR. We also screened 237 lung cancer family probands, in addition to 45 bronchoalveolar tumors, and found that none of them contained the EGFR-T790M mutation. Our observations show that EGFR-T790M provides a proliferative advantage with respect to WT EGFR and suggest that the enhanced kinase activity of this mutant is the basis for rare cases of inherited susceptibility to lung cancer. [Cancer Res 2007;67(10):4665–70]
Identification of a Novel Tumor Suppressor Gene
p34
on Human Chromosome 6q25.1
Abstract In this study, we observed loss of heterozygosity (LOH) in human chromosomal fragment 6q25.1 in sporadic lung cancer patients. LOH was observed in 65% of the 26 lung tumors examined and was narrowed down to a 2.2-Mb region. Single-nucleotide polymorphism (SNP) analysis of genes located within this region identified a candidate gene, termed p34. This gene, also designated as ZC3H12D, C6orf95, FLJ46041, or dJ281H8.1, carries an A/G nonsynonymous SNP at codon 106, which alters the amino acid from lysine to arginine. Nearly 73% of heterozygous lung cancer tissues with LOH and the A/G SNP also exhibited loss of the A allele. In vitro clonogenic and in vivo nude mouse studies showed that overexpression of the A allele exerts tumor suppressor function compared with the G allele. p34 is located within a recently mapped human lung cancer susceptibility locus, and association of the p34 A/G SNP was tested among these families. No significant association between the less frequent G allele and lung cancer susceptibility was found. Our results suggest that p34 may be a novel tumor suppressor gene involved in sporadic lung cancer but it seems not to be the candidate familial lung cancer susceptibility gene linked to chromosomal region 6q23-25. [Cancer Res 2007;67(1):93–9]