David C. Qian

Identification of functional and expression polymorphisms associated with risk for anti-neutrophil cytoplasmic autoantibody-associated vasculitis

To identify risk alleles relevant to the causal and biologic mechanisms of antineutrophil cytoplasmic antibody (ANCA)–associated vasculitis (AAV).

A Novel Pathway-Based Approach Improves Lung Cancer Risk Prediction Using Germline Genetic Variations

Background: Although genome-wide association studies (GWAS) have identified many genetic variants that are strongly associated with lung cancer, these variants have low penetrance and serve as poor predictors of lung cancer in individuals. We sought to increase the predictive value of germline variants by considering their cumulative effects in the context of biologic pathways. Methods: For individuals in the Environment and Genetics in Lung Cancer Etiology study (1,815 cases/1,971 controls), we computed pathway-level susceptibility effects as the sum of relevant SNP variant alleles weighted by their log-additive effects from a separate lung cancer GWAS meta-analysis (7,766 cases/37,482 controls). Logistic regression models based on age, sex, smoking, genetic variants, and principal components of pathway effects and pathway–smoking interactions were trained and optimized in cross-validation and further tested on an independent dataset (556 cases/830 controls). We assessed prediction performance using area under the receiver operating characteristic curve (AUC). Results: Compared with typical binomial prediction models that have epidemiologic predictors (AUC = 0.607) in addition to top GWAS variants (AUC = 0.617), our pathway-based smoking-interactive multinomial model significantly improved prediction performance in external validation (AUC = 0.656, P < 0.0001). Conclusions: Our biologically informed approach demonstrated a larger increase in AUC over nongenetic counterpart models relative to previous approaches that incorporate variants. Impact: This model is the first of its kind to evaluate lung cancer prediction using subtype-stratified genetic effects organized into pathways and interacted with smoking. We propose pathway–exposure interactions as a potentially powerful new contributor to risk inference. Cancer Epidemiol Biomarkers Prev; 25(8); 1208–15. ©2016 AACR.

Identification of shared and unique susceptibility pathways among cancers of the lung, breast, and prostate from genome-wide association studies and tissue-specific protein interactions

Results from genome-wide association studies (GWAS) have indicated that strong single-gene effects are the exception, not the rule, for most diseases. We assessed the joint effects of germline genetic variations through a pathway-based approach that considers the tissue-specific contexts of GWAS findings. From GWAS meta-analyses of lung cancer (12 160 cases/16 838 controls), breast cancer (15 748 cases/18 084 controls) and prostate cancer (14 160 cases/12 724 controls) in individuals of European ancestry, we determined the tissue-specific interaction networks of proteins expressed from genes that are likely to be affected by disease-associated variants. Reactome pathways exhibiting enrichment of proteins from each network were compared across the cancers. Our results show that pathways associated with all three cancers tend to be broad cellular processes required for growth and survival. Significant examples include the nerve growth factor (P = 7.86 × 10(-33)), epidermal growth factor (P = 1.18 × 10(-31)) and fibroblast growth factor (P = 2.47 × 10(-31)) signaling pathways. However, within these shared pathways, the genes that influence risk largely differ by cancer. Pathways found to be unique for a single cancer focus on more specific cellular functions, such as interleukin signaling in lung cancer (P = 1.69 × 10(-15)), apoptosis initiation by Bad in breast cancer (P = 3.14 × 10(-9)) and cellular responses to hypoxia in prostate cancer (P = 2.14 × 10(-9)). We present the largest comparative cross-cancer pathway analysis of GWAS to date. Our approach can also be applied to the study of inherited mechanisms underlying risk across multiple diseases in general.

seXY: a tool for sex inference from genotype arrays.

Motivation: Checking concordance between reported sex and genotype‐inferred sex is a crucial quality control measure in genome‐wide association studies (GWAS). However, limited insights exist regarding the true accuracy of software that infer sex from genotype array data. Results: We present seXY, a logistic regression model trained on both X chromosome heterozygosity and Y chromosome missingness, that consistently demonstrated >99.5% sex inference accuracy in cross‐validation for 889 males and 5,361 females enrolled in prostate cancer and ovarian cancer GWAS. Compared to PLINK, one of the most popular tools for sex inference in GWAS that assesses only X chromosome heterozygosity, seXY achieved marginally better male classification and 3% more accurate female classification. Availability and Implementation: https://github.com/Christopher‐Amos‐Lab/seXY Contact: Christopher.I.Amos@dartmouth.edu Supplementary information: Supplementary data are available at Bioinformatics online.

Fine mapping of MHC region in lung cancer highlights independent susceptibility loci by ethnicity

The basis for associations between lung cancer and major histocompatibility complex genes is not completely understood. Here the authors further consider genetic variation within the MHC region in lung cancer patients and identify independent associations within HLA genes that explain MHC lung cancer associations in Europeans and Asian populations.AbstractLung cancer has several genetic associations identified within the major histocompatibility complex (MHC); although the basis for these associations remains elusive. Here, we analyze MHC genetic variation among 26,044 lung cancer patients and 20,836 controls densely genotyped across the MHC, using the Illumina Illumina OncoArray or Illumina 660W SNP microarray. We impute sequence variation in classical HLA genes, fine-map MHC associations for lung cancer risk with major histologies and compare results between ethnicities. Independent and novel associations within HLA genes are identified in Europeans including amino acids in the HLA-B*0801 peptide binding groove and an independent HLA-DQB1*06 loci group. In Asians, associations are driven by two independent HLA allele sets that both increase risk in HLA-DQB1*0401 and HLA-DRB1*0701; the latter better represented by the amino acid Ala-104. These results implicate several HLA–tumor peptide interactions as the major MHC factor modulating lung cancer susceptibility.

Novel genetic variants in the P38MAPK pathway gene ZAK and susceptibility to lung cancer

The P38MAPK pathway participates in regulating cell cycle, inflammation, development, cell death, cell differentiation, and tumorigenesis. Genetic variants of some genes in the P38MAPK pathway are reportedly associated with lung cancer risk. To substantiate this finding, we used six genome‐wide association studies (GWASs) to comprehensively investigate the associations of 14 904 single nucleotide polymorphisms (SNPs) in 108 genes of this pathway with lung cancer risk. We identified six significant lung cancer risk‐associated SNPs in two genes (CSNK2B and ZAK) after correction for multiple comparisons by a false discovery rate (FDR) <0.20. After removal of three CSNK2B SNPs that are located in the same locus previously reported by GWAS, we performed the LD analysis and found that rs3769201 and rs7604288 were in high LD. We then chose two independent representative SNPs of rs3769201 and rs722864 in ZAK for further analysis. We also expanded the analysis by including these two SNPs from additional GWAS datasets of Harvard University (984 cases and 970 controls) and deCODE (1319 cases and 26 380 controls). The overall effects of these two SNPs were assessed using all eight GWAS datasets (OR = 0.92, 95%CI = 0.89‐0.95, and P = 1.03 × 10−5 for rs3769201; OR = 0.91, 95%CI = 0.88‐0.95, and P = 2.03 × 10−6 for rs722864). Finally, we performed an expression quantitative trait loci (eQTL) analysis and found that these two SNPs were significantly associated with ZAK mRNA expression levels in lymphoblastoid cell lines. In conclusion, the ZAK rs3769201 and rs722864 may be functional susceptibility loci for lung cancer risk.

Genome-wide association study of familial lung cancer

To identify genetic variation associated with lung cancer risk, we performed a genome-wide association analysis of 685 lung cancer cases that had a family history of two or more first or second degree relatives compared with 744 controls without lung cancer that were genotyped on an Illumina Human OmniExpressExome-8v1 array. To ensure robust results, we further evaluated these findings using data from six additional studies that were assembled through the Transdisciplinary Research on Cancer of the Lung Consortium comprising 1993 familial cases and 33 690 controls. We performed a meta-analysis after imputation of all variants using the 1000 Genomes Project Phase 1 (version 3 release date September 2013). Analyses were conducted for 9 327 222 SNPs integrating data from the two sources. A novel variant on chromosome 4p15.31 near the LCORL gene and an imputed rare variant intergenic between CDKN2A and IFNA8 on chromosome 9p21.3 were identified at a genome-wide level of significance for squamous cell carcinomas. Additionally, associations of CHRNA3 and CHRNA5 on chromosome 15q25.1 in sporadic lung cancer were confirmed at a genome-wide level of significance in familial lung cancer. Previously identified variants in or near CHRNA2, BRCA2, CYP2A6 for overall lung cancer, TERT, SECISPB2L and RTEL1 for adenocarcinoma and RAD52 and MHC for squamous carcinoma were significantly associated with lung cancer.

Genome-wide interaction study of smoking behavior and non-small cell lung cancer risk in Caucasian population

Non-small cell lung cancer is the most common type of lung cancer. Both environmental and genetic risk factors contribute to lung carcinogenesis. We conducted a genome-wide interaction analysis between single nucleotide polymorphisms (SNPs) and smoking status (never- versus ever-smokers) in a European-descent population. We adopted a two-step analysis strategy in the discovery stage: we first conducted a case-only interaction analysis to assess the relationship between SNPs and smoking behavior using 13336 non-small cell lung cancer cases. Candidate SNPs with P-value <0.001 were further analyzed using a standard case-control interaction analysis including 13970 controls. The significant SNPs with P-value <3.5 × 10-5 (correcting for multiple tests) from the case-control analysis in the discovery stage were further validated using an independent replication dataset comprising 5377 controls and 3054 non-small cell lung cancer cases. We further stratified the analysis by histological subtypes. Two novel SNPs, rs6441286 and rs17723637, were identified for overall lung cancer risk. The interaction odds ratio and meta-analysis P-value for these two SNPs were 1.24 with 6.96 × 10-7 and 1.37 with 3.49 × 10-7, respectively. In addition, interaction of smoking with rs4751674 was identified in squamous cell lung carcinoma with an odds ratio of 0.58 and P-value of 8.12 × 10-7. This study is by far the largest genome-wide SNP-smoking interaction analysis reported for lung cancer. The three identified novel SNPs provide potential candidate biomarkers for lung cancer risk screening and intervention. The results from our study reinforce that gene-smoking interactions play important roles in the etiology of lung cancer and account for part of the missing heritability of this disease.

PI3K/Akt/mTOR Signaling and Plasma Membrane Proteins Are Implicated in Responsiveness to Adjuvant Dendritic Cell Vaccination for Metastatic Colorectal Cancer

Purpose: We have previously demonstrated that patients with metastatic colorectal cancer who exhibit immune responses to a dendritic cell (DC) vaccine have superior recurrence-free survival following surgery, compared with patients in whom responses do not occur. We sought to characterize the patterns of T-lymphocyte infiltration and somatic mutations in metastases that are associated with and predictive of response to the DC vaccine. Experimental Design: Cytotoxic, memory, and regulatory T cells in resected metastases and surrounding normal liver tissue from 22 patients (11 responders and 11 nonresponders) were enumerated by immunohistochemistry prior to vaccine administration. In conjunction with tumor sequencing, the combined multivariate and collapsing method was used to identify gene mutations that are associated with vaccine response. We also derived a response prediction score for each patient using his/her tumor genotype data and variant association effect sizes computed from the other 21 patients; greater weighting was placed on gene products with cell membrane–related functions. Results: There was no correlation between vaccine response and intratumor, peritumor, or hepatic densities of T-cell subpopulations. Associated genes were found to be enriched in the PI3K/Akt/mTOR signaling axis (P < 0.001). Applying a consistent prediction score cutoff over 22 rounds of leave-one-out cross-validation correctly inferred vaccine response in 21 of 22 patients (95%). Conclusions: Adjuvant DC vaccination has shown promise as a form of immunotherapy for patients with metastatic colorectal cancer. Its efficacy may be influenced by somatic mutations that affect pathways involving PI3K, Akt, and mTOR, as well as tumor surface proteins. Clin Cancer Res; 23(2); 399–406. ©2016 AACR.

Abstract 2233: PI3K/Akt/mTOR signaling and plasma membrane proteins are implicated in responsiveness to adjuvant dendritic cell vaccination for metastatic colorectal cancer

Purpose: We have previously demonstrated that metastatic colorectal cancer patients who exhibit immune responses to a dendritic cell (DC) vaccine have superior recurrence-free survival following surgery, compared to patients in whom immune responses do not occur. We sought to characterize the patterns of T lymphocyte infiltration and somatic mutations in metastases that are associated with and predictive of response to the DC vaccine. Methods: Cytotoxic, memory, and regulatory T cells in resected metastases and in surrounding normal liver tissue from 22 patients (11 responders and 11 non-responders) were enumerated by immunohistochemistry prior to vaccine administration. In conjunction with tumor sequencing, the Combined Multivariate and Collapsing method was used to identify gene mutations that are associated with vaccine response. We also derived a response prediction score for each patient using his/her tumor genotype data and variant association effect sizes computed from the other 21 patients; greater weighting was placed on genes that encode plasma membrane proteins. Results: There was no relationship between vaccine response and intra-tumor, peri-tumor, or hepatic densities of T cell subpopulations. Associated genes were found to be statistically enriched in PI3K, Akt, and mTOR signaling pathways (P Conclusions: Adjuvant dendritic cell vaccination has shown promise as a form of immunotherapy for patients with metastatic colorectal cancer. Its efficacy may be influenced by somatic mutations that affect pathways involving PI3K, Akt, and mTOR, as well as neoantigens on tumor cell surfaces. Citation Format: David Qian, Jinyoung Byun, Xiangjun Xiao, Stephanie Her, Arief Suriawinata, Christopher Amos, Richard Barth. PI3K/Akt/mTOR signaling and plasma membrane proteins are implicated in responsiveness to adjuvant dendritic cell vaccination for metastatic colorectal cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2233.