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Microorganisms are commonly detected in tumor tissues, and the species and abundance have been reported to affect cancer initiation, progression, and therapy. Host genetics have been associated with gut microbial abundances, while the relationships between genetic variants and the cancer microbiome still require systematic interrogation. Therefore, identification of cancer microbiome quantitative trait loci (mbQTL) across cancer types might elucidate the contributions of genetic variants to tumor development. Using genotype data from The Cancer Genome Atlas and microbial abundance levels from Kraken-derived data, we developed a computational pipeline to identify mbQTLs in 32 cancer types. This study systematically identified 38,660 mbQTLs across cancers, ranging 50 in endometrial carcinoma to 3,133 in thyroid carcinoma. Furthermore, a strong enrichment of mbQTLs was observed among transcription factor binding sites and chromatin regulatory elements, such as H3K27ac. Notably, mbQTLs were significantly enriched in cancer genome-wide association studies (GWAS) loci and explained an average of 2% for cancer heritability, indicating that mbQTLs could provide additional insights into cancer etiology. Correspondingly, 24,443 mbQTLs overlapping with GWAS linkage disequilibrium regions were identified. Survival analyses identified 318 mbQTLs associated with patient overall survival. Moreover, we uncovered 135,248 microbiome–immune infiltration associations and 166,603 microbiome–drug response associations that might provide clues for microbiome-based biomarkers. Finally, a user-friendly database, Cancer-mbQTL (http://canmbqtl.whu.edu.cn/#/), was constructed for users to browse, search, and download data of interest. This study provides a valuable resource for investigating the roles of genetics and microorganisms in human cancer. Significance: This study provides insights into the host–microbiome interactions for multiple cancer types, which could help the research community understand the effects of inherited variants in tumorigenesis and development.

Understanding the genetic variation underlying transcript splicing is essential for fully dissecting the molecular mechanisms of common diseases. The available evidence from splicing quantitative trait locus (sQTL) studies using pancreatic ductal adenocarcinoma (PDAC) tissues have been limited to small sample sizes. Here we present a genome-wide sQTL analysis to identify SNP that control mRNA splicing in 176 PDAC samples from TCGA. From this analysis, 16,175 sQTLs were found to be significantly enriched in RNA-binding protein (RBP) binding sites and chromatin regulatory elements and overlapped with known loci from PDAC genome-wide association studies (GWAS). sQTLs and expression quantitative trait loci (eQTL) showed mostly nonoverlapping patterns, suggesting sQTLs provide additional insights into the etiology of disease. Target genes affected by sQTLs were closely related to cancer signaling pathways, high mutational burden, immune infiltration, and pharmaceutical targets, which will be helpful for clinical applications. Integration of a large-scale population consisting of 2,782 patients with PDAC and 7,983 healthy controls identified an sQTL variant rs1785932-T allele that promotes alternative splicing of ELP2 exon 6 and leads to a lower level of the ELP2 full-length isoform (ELP2_V1) and a higher level of a truncated ELP2 isoform (ELP2_V2), resulting in decreased risk of PDAC [OR = 0.83; 95% confidence interval (CI), 0.77–0.89; P = 1.16 × 10−6]. The ELP2_V2 isoform functioned as a potential tumor suppressor gene, inhibiting PDAC cell proliferation by exhibiting stronger binding affinity to JAK1/STAT3 than ELP2_V1 and subsequently blocking the pathologic activation of the phosphorylated STAT3 (pSTAT3) pathway. Collectively, these findings provide an informative sQTL resource and insights into the regulatory mechanisms linking splicing variants to PDAC risk.Significance:In pancreatic cancer, splicing quantitative trait loci analysis identifies a rs1785932 variant that contributes to decreased risk of disease by influencing ELP2 mRNA splicing and blocking the STAT3 oncogenic pathway.

Although genome-wide association studies (GWAS) have identified more than 100 colorectal cancer risk loci, most of the biological mechanisms associated with these loci remain unclear. Here we first performed a comprehensive expression quantitative trait loci analysis in colorectal cancer tissues adjusted for multiple confounders to test the determinants of germline variants in established GWAS susceptibility loci on mRNA and long noncoding RNA (lncRNA) expression. Combining integrative functional genomic/epigenomic analyses and a large-scale population study consisting of 6,024 cases and 10,022 controls, we then prioritized rs174575 with a C>G change as a potential causal candidate for colorectal cancer at 11q12.2, as its G allele was associated with an increased risk of colorectal cancer (OR = 1.26; 95% confidence interval = 1.17–1.36; P = 2.57 × 10–9). rs174575 acted as an allele-specific enhancer to distally facilitate expression of both FADS2 and lncRNA AP002754.2 via long-range enhancer–promoter interaction loops, which were mediated by E2F1. AP002754.2 further activated a transcriptional activator that upregulated FADS2 expression. FADS2, in turn, was overexpressed in colorectal cancer tumor tissues and functioned as a potential oncogene that facilitated colorectal cancer cell proliferation and xenograft growth in vitro and in vivo by increasing the metabolism of PGE2, an oncogenic molecule involved in colorectal cancer tumorigenesis. Our findings represent a novel mechanism by which a noncoding variant can facilitate long-range genome interactions to modulate the expression of multiple genes including not only mRNA, but also lncRNA, which provides new insights into the understanding of colorectal cancer etiology. Significance: This study provides an oncogenic regulatory circuit among several oncogenes including E2F1, FADS2, and AP002754.2 underlying the association of rs174575 with colorectal cancer risk, which is driven by long-range enhancer–promoter interaction loops.

Although genome-wide association studies (GWAS) have identified more than 100 colorectal cancer risk loci, most of the biological mechanisms associated with these loci remain unclear. Here we first performed a comprehensive expression quantitative trait loci analysis in colorectal cancer tissues adjusted for multiple confounders to test the determinants of germline variants in established GWAS susceptibility loci on mRNA and long noncoding RNA (lncRNA) expression. Combining integrative functional genomic/epigenomic analyses and a large-scale population study consisting of 6,024 cases and 10,022 controls, we then prioritized rs174575 with a CG change as a potential causal candidate for colorectal cancer at 11q12.2, as its G allele was associated with an increased risk of colorectal cancer (OR = 1.26; 95% confidence interval = 1.17-1.36

Genome-wide association studies (GWAS) of colorectal cancer have identified several common susceptible variants in gene regulatory regions. However, low-frequency or rare coding risk variants have not been systematically investigated in patients with colorectal cancer from Chinese populations. In this study, we performed an exome-wide association analysis with 1,062 patients with colorectal cancer and 2,184 controls from a Chinese population. Promising associations were further replicated in two replication sets: replication stage I with 2,478 cases and 3,880 controls, and replication stage II with 3,761 cases and 4,058 controls. We identified two variants significantly associated with colorectal cancer risk: a novel rare missense variant in TCF7L2 [rs138649767, OR = 2.08, 95% confidence interval (CI): 1.69–2.57, P = 5.66 × 10−12] and a previous European GWAS-identified 3′-UTR variant in ATF1 (rs11169571, OR = 1.18, 95% CI: 1.13–1.24, P = 1.65 × 10−12). We found a significant interaction between the TCF7L2 missense variant rs138649767 and a previous GWAS-identified regulatory variant rs6983267 in the MYC enhancer (Pinteraction = 0.0002). Functional analysis of this variant revealed that TCF7L2 with rs138649767-A allele harbored the ability to activate the MYC enhancer with rs6983267-G allele and enhance colorectal cancer cell proliferation. In addition, the ATF1 rs11169571 variant significantly correlated with ATF1 expression by affecting hsa-miR-1283 and hsa-miR-520d-5p binding. Further ChIP-seq and gene coexpression analyses showed that oncogenes NRAS and BRAF were activated by ATF1 in colorectal cancer. These results widen our understanding of the molecular basis of colorectal cancer risk and provide insight into pathways that might be targeted to prevent colorectal cancer. Significance: Exome-wide association analysis identifies a rare missense variant in TCF7L2 and a common regulatory variant in ATF1 as susceptibility factors of colorectal cancer. Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/78/17/5164/F1.large.jpg. Cancer Res; 78(17); 5164–72. ©2018 AACR.

The heat shock protein Hsp70 is crucial for regulating cellular homeostasis in stressed cells. Although the tumorigenic potential and prognostic applications of Hsp70 have been widely investigated, it remains unclear whether genetic variations of the human isoforms HSPA1L, HSPA1A, and HSPA1B are associated with cancer risk and prognosis. In this study, we genotyped six tagSNPs in these genes in 1,152 paired patients with lung cancer and controls, and then validated the results in additional cohorts of 1,781 patients with lung cancer and 1,038 controls. In addition, we evaluated the associations of these tagSNPs with survival in 330 patients with advanced non–small cell lung cancer (NSCLC) with additional validation in another 331 patients with advanced NSCLC. Functions of the risk variants identified were investigated using cell-based reporter assays. We found that the HSPA1B rs6457452T allele was associated with increased lung cancer risk compared with the rs6457452C allele in both data sets and also pooled analysis (adjusted OR = 1.41; P = 2.8 × 10−5). The HSPA1B rs2763979TT genotype conferred poor survival outcomes for patients with advanced NSCLC in two independent cohorts and pooled analysis [adjusted hazard ratio (HR) = 1.80, 1.61, and 1.66; P = 0.013, 0.036, and 0.002, respectively]. Lastly, we also found that the rs2763979T and rs6457452T alleles were each sufficient to reduce expression of transcriptional reporter constructs, when compared with the rs2763979C and rs6457452C alleles, respectively. Taken together, our findings define that functional HSPA1B variants are associated with lung cancer risk and survival. These Hsp70 genetic variants may offer useful biomarkers to predict lung cancer risk and prognosis. Cancer Res; 71(24); 7576–86. ©2011 AACR.

Although most patients with small-cell lung cancer respond to chemotherapy, the survival time is highly diverse. We conducted a genome-wide analysis to examine whether germline genetic variations are prognostic factors in small-cell lung cancer patients treated with the same chemotherapy regimen. Genome-wide scan of single nucleotide polymorphisms (SNP) was performed using blood DNA to identify genotypes associated with overall survival in 245 patients treated with platinum-based chemotherapy, and the results were replicated in another independent set of 305 patients. Associations were estimated by Cox models and function of the variants was examined by biochemical assays. We found that rs1820453 T>G SNP within the promoter region of YAP1 on chromosome 11q22 and rs716274 A>G SNP in the region of downstream of DYNC2H1 on chromosome 11q22.3 are associated with small-cell lung cancer survival. In pooled analysis of 2 independent cohorts, the adjusted hazard ratio for patients with the rs1820453 TG or GG genotype was 1.49 (95% CI, 1.19–1.85; P = 0.0004) and 1.65 (95% CI, 1.36–2.01; P = 4.76 × 10−7), respectively, compared with the TT genotype; and for patients with the rs716274 AG or GG genotype was 1.83 (95% CI, 1.47–2.29; P = 8.74 × 10−8) and 2.96 (95% CI, 1.90–4.62; P = 1.59 × 10−6), respectively, compared with the AA genotype. Functional analysis showed that the rs1820453 T>G change creates a transcriptional factor binding site and results in downregulation of YAP1 expression. These results suggest that YAP1 may play an important role in prognosis of small-cell lung cancer patients treated with platinum-based chemotherapy. Cancer Res; 70(23); 9721–9. ©2010 AACR.

Matrix metalloproteinase-2 (MMP-2) plays important roles in cancer development and aggression. Our previous studies revealed a strong association between the MMP-2 −1306C/T polymorphism and risk of several cancers. A novel −735C/T polymorphism in MMP-2 promoter has been identified but the function is undefined. This study examined our hypothesis that these two polymorphisms might have functional relevance and impact on risk of esophageal squamous cell carcinoma in the context of haplotype. Genotypes and haplotypes were analyzed in 527 cases and 777 controls and odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by logistic regression. The function of the polymorphisms was examined by electrophoretic mobility shift assays, luciferase gene expression assays, and reverse transcriptase-PCR analyses. It was found that the −735C→T transition disrupts an Sp1 site and displays a lower promoter activity. The C-1306–C-735 haplotype had 7-fold increased luciferase expression and 3.7-fold increased MMP-2 mRNA levels in esophageal tissues compared with the T-1306–T-735 haplotype. A case-control analysis revealed a 1.52-fold (95% CI = 1.17–1.96) or 1.30-fold (95% CI = 1.04–1.63) excess risk of developing esophageal squamous cell carcinoma for the −1306CC or −735CC genotype carriers compared with noncarriers, respectively. A greater association was observed between elevated risk of developing esophageal squamous cell carcinoma and C-1306 or C-735 allele containing haplotypes, with the risk being highest for the C-1306–C-735 haplotype compared with the T-1306–T-735 haplotype (OR = 6.53; 95% CI = 2.78–15.33). The C-1306–C-735 haplotype was also associated with increased risk for distant metastasis of esophageal squamous cell carcinoma (OR = 3.34; 95% CI = 1.16–9.63). These findings suggest that the C-1306–C-735 haplotype in the MMP-2 promoter contributes to risk of the occurrence and metastasis of esophageal squamous cell carcinoma by increasing expression of MMP-2.

The tumor suppressor P53 pathway plays a crucial role in preventing carcinogenesis and genetic variations of this pathway may be associated with cancer susceptibility. We tested this hypothesis by examining the contribution of functional polymorphisms in P53 and MDM2 to risk of esophageal squamous cell carcinoma (ESCC). DNA from 758 ESCC patients and 1,420 controls were genotyped for P53 codon 72Arg>Pro and MDM2 309T>G polymorphisms. Odds ratios (OR) and 95% confidence intervals (CI) of ESCC were estimated by logistic regression. We observed an increased risk of ESCC associated with the P53 Pro/Pro (OR, 1.83; 95% CI, 1.43-2.35; P < 0.001) or MDM2 GG (OR, 1.49; 95% CI, 1.16-1.91; P = 0.002) genotype, compared with the P53 Arg/Arg or MDM2 TT genotype, respectively. Interaction between these P53 and MDM2 polymorphisms increased risk of ESCC in a multiplicative manner, with the OR being 3.10 (95% CI, 2.07-4.69) for subjects carrying both P53 Pro/Pro and MDM2 GG genotypes. Significant interactions were observed between these polymorphisms and smoking, with risk being the highest (OR, 5.29; 95% CI, 2.91-9.61) in smokers having both P53 Pro/Pro and MDM2 GG genotypes. The MDM2 GG genotype was also associated with risk of developing poorly differentiated and advanced ESCC compared with the GT or TT genotype (OR for high-grade and stages III-IV versus low-grade and stages I-II = 1.60; 95% CI, 1.00-2.64; P = 0.049). The P53 and MDM2 polymorphisms may be genetic determinants for the development of ESCC.

The etiology of esophageal squamous cell carcinoma (ESCC) has been shown to be associated with genetic and certain environmental factors that produce DNA damage. Base excision repair (BER) genes are responsible for repair of DNA damage caused by reactive oxygen species and other electrophiles and therefore are good candidate susceptibility genes for ESCC. We first screened eight BER genes for new and potential functional polymorphisms by resequencing 27 DNA samples. We then identified and genotyped for important tagging single nucleotide polymorphisms (SNPs) in a case-control study of 419 patients with newly diagnosed esophageal cancer and 480 healthy controls by frequency matching on age and sex. The association between genotypes and ESCC risk was estimated by unconditional multivariate logistic regression analysis, and stepwise regression procedure was used for constructing the final logistic regression model. We identified 129 SNPs in the eight BER genes, including 18 SNPs that cause amino acid changes. In the final model, 4 SNPs, including 2 in the coding regions (ADPRT Val762Ala and MBD4 Glu346Lys) and others in noncoding regions (LIG3 A3704G and XRCC1 T-77C), remained as significant predictors for the risk of ESCC. The adjusted odd ratios were 1.25 [95% confidence interval (CI) 1.02–1.53] for the ADPRT 762Ala allele, 1.25 (95% CI 1.02–1.53) for the MBD4 346 Lys allele, 0.78 (95% CI 0.63–0.97) for the LIG3 3704G allele, and 1.38 (95% CI 1.01–1.89) for the XRCC1–77C allele. In addition, we observed a significant gene-gene interaction between XRCC1 Gln399Arg and ADPRT Val762Ala. The results suggest that the polymorphisms in five BER genes may be associated with the susceptibility to ESCC in a Chinese population.

STK15/BTAK/Aurora-A involved in regulating centrosomes and chromosome segregation is amplified and overexpressed in human cancers. A T91A polymorphism in STK15 causes Phe31Ile substitution, and the 31Ile variant has been shown to be preferentially amplified and associated with degree of aneuploidy in human tumors. We genotyped 656 patients with esophageal squamous cell carcinoma (ESCC) and 656 controls for the polymorphism to examine the hypothesis that the STK15 variation may affect individual susceptibility to the occurrence and aggression of ESCC. It was found that the Ile/Ile genotype was significantly associated with increased risk of ESCC occurrence [odds ratio (OR) = 1.97, 95% confidence interval (CI) = 1.36–2.85] compared with the Phe/Phe genotype. The 31Ile allele frequency significantly increased as ESCC stage increased (trend test, P = 0.006). Patients with the Ile/Ile genotype had an increased risk for invasive disease (stage II-IV; OR = 2.13, 95% CI = 1.04–4.39) or metastatic disease (stage III and IV; OR = 2.31, 95% CI = 1.06–5.05) compared with those with the Phe/Phe genotype. A positive correlation between the Ile/Ile genotype and high ESCC grade was also observed. Our results demonstrate for the first time that the STK15 polymorphism is a genetic susceptibility factor for the occurrence and aggression of ESCC.

Cytochrome P450 2A13 (CYP2A13), an enzyme expressed predominantly in the human respiratory tract, exhibits high efficiency in the metabolic activation of tobacco carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). A C--T transition in the CYP2A13 gene causes Arg257Cys amino acid substitution and, thus, results in a significantly reduced activity toward NNK and other substrates. In this case-control study, we genotyped 724 patients with lung cancer and 791 controls for this polymorphism to examine the hypothesis that the variant CYP2A13 may have impact on risk of lung cancer in relation to tobacco smoking. A gene deletion polymorphism (CYP2A6*4) in CYP2A6, another enzyme involved in the metabolic activation of tobacco nitrosamines, was also analyzed as a comparison. We found that, compared with the CC genotype, the variant CYP2A13 genotype (CT + TT) was associated with substantially reduced risk for lung adenocarcinoma [odds ratio (OR), 0.41; 95% confidence interval (CI), 0.23-0.71], but not squamous cell carcinoma (OR, 0.86; 95% CI, 0.57-1.29) or other types of lung cancer (OR, 0.58; 95% CI, 0.32-1.09). Stratification analysis shows that the reduced risk of lung adenocarcinoma related to the variant CYP2A13 genotype was limited to smokers, especially light smokers (OR, 0.23; 95% CI, 0.08-0.68) but not nonsmokers or heavy smokers. No association was observed between CYP2A6 genotype and risk of lung cancer. Our results demonstrate for the first time that the variant CYP2A13 allele is associated with reduced risk of lung adenocarcinoma, suggesting the role of NNK-CYP2A13 interaction as a causative factor for the cancer.