Variation at 2q35 (PNKD and TMBIM1) influences colorectal cancer risk and identifies a pleiotropic effect with inflammatory bowel disease

A prognostic risk model based on lactate metabolism and transport-related lncRNAs for gastric adenocarcinoma

BACKGROUND

Increased lactate levels and metastasis in tumours are strongly associated with dismal outcomes. But prognostic value of lactate metabolism and transport-related lncRNAs in gastric adenocarcinoma (GA) patients remains unaddressed.

METHODS

Gene expression data of GA were provided by The Cancer Genome Atlas. Lactate metabolism and transport-related gene data were accessed from GSEA. LncRNAs related to lactate metabolism and transport were identified by correlation analysis. A prognostic model was built by regression analysis. Validity of prognostic model was confirmed through survival analysis and receiver operating characteristic (ROC) curve. Immunity of each risk group was evaluated by immune correlation analysis .LncRNA-mRNA network was built by correlation analysis using Cytoscape software.

RESULTS

A 12-gene prognostic model based on lactate metabolism and transport-related lncRNAs was built in GA. Median riskscore was utilized to classify GA samples into high- and low-risk groups. Survival analysis and ROC curves demonstrated validity of prognostic model. Most immune checkpoint molecules and TIDE scores were lower in the low-risk group. LINC01303 and LINC01545 may be the key prognostic factors in patients with GA.

CONCLUSION

This study successfully built a prognostic model of lactate metabolism and transport-related lncRNAs in GA. The findings guide prognostic management of GA patients.

Genetic risk impacts the association of menopausal hormone therapy with colorectal cancer risk

BACKGROUND

Menopausal hormone therapy (MHT), a common treatment to relieve symptoms of menopause, is associated with a lower risk of colorectal cancer (CRC). To inform CRC risk prediction and MHT risk-benefit assessment, we aimed to evaluate the joint association of a polygenic risk score (PRS) for CRC and MHT on CRC risk.

METHODS

We used data from 28,486 postmenopausal women (11,519 cases and 16,967 controls) of European descent. A PRS based on 141 CRC-associated genetic variants was modeled as a categorical variable in quartiles. Multiplicative interaction between PRS and MHT use was evaluated using logistic regression. Additive interaction was measured using the relative excess risk due to interaction (RERI). 30-year cumulative risks of CRC for 50-year-old women according to MHT use and PRS were calculated.

RESULTS

The reduction in odds ratios by MHT use was larger in women within the highest quartile of PRS compared to that in women within the lowest quartile of PRS (p-value = 2.7 × 10-8). At the highest quartile of PRS, the 30-year CRC risk was statistically significantly lower for women taking any MHT than for women not taking any MHT, 3.7% (3.3%-4.0%) vs 6.1% (5.7%-6.5%) (difference 2.4%, P-value = 1.83 × 10-14); these differences were also statistically significant but smaller in magnitude in the lowest PRS quartile, 1.6% (1.4%-1.8%) vs 2.2% (1.9%-2.4%) (difference 0.6%, P-value = 1.01 × 10-3), indicating 4 times greater reduction in absolute risk associated with any MHT use in the highest compared to the lowest quartile of genetic CRC risk.

CONCLUSIONS

MHT use has a greater impact on the reduction of CRC risk for women at higher genetic risk. These findings have implications for the development of risk prediction models for CRC and potentially for the consideration of genetic information in the risk-benefit assessment of MHT use.

Impact of ambient air pollution on colorectal cancer risk and survival: insights from a prospective cohort and epigenetic Mendelian randomization study

BACKGROUND

This study investigates the associations between air pollution and colorectal cancer (CRC) risk and survival from an epigenomic perspective.

METHODS

Using a newly developed Air Pollutants Exposure Score (APES), we utilized a prospective cohort study (UK Biobank) to investigate the associations of individual and combined air pollution exposures with CRC incidence and survival, followed by an up-to-date systematic review with meta-analysis to verify the associations. In epigenetic two-sample Mendelian randomization analyses, we examine the associations between genetically predicted DNA methylation related to air pollution and CRC risk. Further genetic colocalization and gene-environment interaction analyses provided different insights to disentangle pathogenic effects of air pollution via epigenetic modification.

FINDINGS

During a median 12.97-year follow-up, 5767 incident CRC cases among 428,632 participants free of baseline CRC and 533 deaths in 2401 patients with CRC were documented in the UK Biobank. A higher APES score was associated with an increased CRC risk (HR, 1.03, 95% CI = 1.01-1.06; P = 0.016) and poorer survival (HR, 1.13, 95% CI = 1.03-1.23; P = 0.010), particularly among participants with insufficient physical activity and ever smokers (Pinteraction > 0.05). A subsequent meta-analysis of seven observational studies, including UK Biobank data, corroborated the association between PM2.5 exposure (per 10 μg/m3 increment) and elevated CRC risk (RR,1.42, 95% CI = 1.12-1.79; P = 0.004; I2 = 90.8%). Genetically predicted methylation at PM2.5-related CpG site cg13835894 near TMBIM1/PNKD and cg16235962 near CXCR5, and NO2-related cg16947394 near TMEM110 were associated with an increased CRC risk. Gene-environment interaction analysis confirmed the epigenetic modification of aforementioned CpG sites with CRC risk and survival.

INTERPRETATION

Our study suggests the association between air pollution and CRC incidence and survival, underscoring the possible modifying roles of epigenomic factors. Methylation may partly mediate pathogenic effects of air pollution on CRC, with annotation to epigenetic alterations in protein-coding genes TMBIM1/PNKD, CXCR5 and TMEM110.

FUNDING

Xue Li is supported by the Natural Science Fund for Distinguished Young Scholars of Zhejiang Province (LR22H260001), the National Nature Science Foundation of China (No. 82204019) and Healthy Zhejiang One Million People Cohort (K-20230085). ET is supported by a Cancer Research UK Career Development Fellowship (C31250/A22804). MGD is supported by the MRC Human Genetics Unit Centre Grant (U127527198).

Prioritization of risk genes in colorectal cancer by integrative analysis of multi-omics data and gene networks

Genome-wide association studies (GWASs) have identified over 140 colorectal cancer (CRC)-associated loci; however, target genes at the majority of loci and underlying molecular mechanisms are poorly understood. Here, we utilized a Bayesian approach, integrative risk gene selector (iRIGS), to prioritize risk genes at CRC GWAS loci by integrating multi-omics data. As a result, a total of 105 high-confidence risk genes (HRGs) were identified, which exhibited strong gene dependencies for CRC and enrichment in the biological processes implicated in CRC. Among the 105 HRGs, CEBPB, located at the 20q13.13 locus, acted as a transcription factor playing critical roles in cancer. Our subsequent assays indicated the tumor promoter function of CEBPB that facilitated CRC cell proliferation by regulating multiple oncogenic pathways such as MAPK, PI3K-Akt, and Ras signaling. Next, by integrating a fine-mapping analysis and three independent case-control studies in Chinese populations consisting of 8,039 cases and 12,775 controls, we elucidated that rs1810503, a putative functional variant regulating CEBPB, was associated with CRC risk (OR=0.90, 95%CI=0.86-0.93, P=1.07×10-7). The association between rs1810503 and CRC risk was further validated in three additional multi-ancestry populations consisting of 24,254 cases and 58,741 controls. Mechanistically, the rs1810503 A to T allele change weakened the enhancer activity in an allele-specific manner to decrease CEBPB expression via long-range promoter-enhancer interactions, mediated by the transcription factor, REST, and thus decreased CRC risk. In summary, our study provides a genetic resource and a generalizable strategy for CRC etiology investigation, and highlights the biological implications of CEBPB in CRC tumorigenesis, shedding new light on the etiology of CRC.

Using DEPendency of Association on the Number of Top Hits (DEPTH) as a Complementary Tool to Identify Novel Colorectal Cancer Susceptibility Loci

BACKGROUND

DEPendency of association on the number of Top Hits (DEPTH) is an approach to identify candidate susceptibility regions by considering the risk signals from overlapping groups of sequential variants across the genome.

METHODS

We applied a DEPTH analysis using a sliding window of 200 SNPs to colorectal cancer data from the Colon Cancer Family Registry (CCFR; 5,735 cases and 3,688 controls), and Genetics and Epidemiology of Colorectal Cancer Consortium (GECCO; 8,865 cases and 10,285 controls) studies. A DEPTH score > 1 was used to identify candidate susceptibility regions common to both analyses. We compared DEPTH results against those from conventional genome-wide association study (GWAS) analyses of these two studies as well as against 132 published susceptibility regions.

RESULTS

Initial DEPTH analysis revealed 2,622 (CCFR) and 3,686 (GECCO) candidate susceptibility regions, of which 569 were common to both studies. Bootstrapping revealed 40 and 49 candidate susceptibility regions in the CCFR and GECCO data sets, respectively. Notably, DEPTH identified at least 82 regions that would not be detected using conventional GWAS methods, nor had they been identified by previous colorectal cancer GWASs. We found four reproducible candidate susceptibility regions (2q22.2, 2q33.1, 6p21.32, 13q14.3). The highest DEPTH scores were in the human leukocyte antigen locus at 6p21 where the strongest associated SNPs were rs762216297, rs149490268, rs114741460, and rs199707618 for the CCFR data, and rs9270761 for the GECCO data.

CONCLUSIONS

DEPTH can identify candidate susceptibility regions for colorectal cancer not identified using conventional analyses of larger datasets.

IMPACT

DEPTH has potential as a powerful complementary tool to conventional GWAS analyses for discovering susceptibility regions within the genome.

Developing and validating polygenic risk scores for colorectal cancer risk prediction in East Asians

Several polygenic risk scores (PRSs) have been developed to predict the risk of colorectal cancer (CRC) in European descendants. We used genome-wide association study (GWAS) data from 22 702 cases and 212 486 controls of Asian ancestry to develop PRSs and validated them in two case-control studies (1454 Korean and 1736 Chinese). Eleven PRSs were derived using three approaches: GWAS-identified CRC risk SNPs, CRC risk variants identified through fine-mapping of known risk loci and genome-wide risk prediction algorithms. Logistic regression was used to estimate odds ratios (ORs) and area under the curve (AUC). PRS115-EAS , a PRS with 115 GWAS-reported risk variants derived from East-Asian data, validated significantly better than PRS115-EUR derived from European descendants. In the Korea validation set, OR per SD increase of PRS115-EAS was 1.63 (95% CI = 1.46-1.82; AUC = 0.63), compared with OR of 1.44 (95% CI = 1.29-1.60, AUC = 0.60) for PRS115-EUR . PRS115-EAS/EUR derived using meta-analysis results of both populations slightly improved the AUC to 0.64. Similar but weaker associations were found in the China validation set. Individuals among the highest 5% of PRS115-EAS/EUR have a 2.52-fold elevated CRC risk compared with the medium (41-60th) risk group and have a 12% to 20% risk of developing CRC by age 85. PRSs constructed using results from fine-mapping and genome-wide algorithms did not perform as well as PRS115-EAS and PRS115-EAS/EUR in risk prediction, possibly due to a small sample size. Our results indicate that CRC PRSs are promising in predicting CRC risk in East Asians and highlights the importance of using population-specific data to build CRC risk prediction models.

Impact of sociodemographic factors and screening, diagnosis, and treatment strategies on colorectal cancer mortality in Brazil: A 20-year ecological study

Colorectal cancer (CRC) caused 261,060 deaths in Brazil over a 20-year period, with a tendency to increase over time. This study aimed to verify the sociodemographic factors predicting higher mortality caused by CRC and survival rates. Moreover, we aimed to verify whether the performance of screening, diagnostic and treatment procedures had an impact on mortality. Ecological observational study of mortality due to CRC was conducted in Brazil from 2000–2019. The adjustment variable was age, which was used to calculate the age-standardized mortality rate (ASMR). The exposure variables were number of deaths and ASMR. Outcome variables were age-period-cohort, race classification, marital status, geographic region, and screening, diagnostic, and treatment procedures. Age-period-cohort analysis was performed. ANOVA and Kruskal-Wallis test with post hoc tests were used to assess differences in race classification, marital status, and geographic region. Multinomial logistic regression was used to test for interaction among sociodemographic factors. Survival analysis included Kaplan-Meier plot and Cox regression analysis were performed. Multivariate linear regression was used to test prediction using screening, diagnosis, and treatment procedures. In Brazil, mortality from CRC increased after age 45 years. The highest adjusted mortality rates were found among white individuals and in the South of the country (p < 0.05). Single, married, and widowed northern and northeastern persons had a higher risk of death than legally separated southern persons (p < 0.05). Lower survival rates were observed in brown and legally separated individuals and residents from the North (p < 0.05). An increase in first-line chemotherapy and a decrease in second-line chemotherapy were associated with high mortality in the north (p<0.05). In the south, second-line chemotherapy and abdominoperineal rectal resection were associated with high mortality (p < 0.05). Regional differences in sociodemographic factors and clinical procedures can serve as guidelines for adjusting public health policies.

TMBIM1 promotes proliferation and attenuates apoptosis in glioblastoma cells by targeting the p38 MAPK signalling pathway

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Our research firstly identified that TMBIM1 promotes proliferation and attenuates apoptosis via the p38/MAPK pathway in GBM.

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We also revealed that TMBIM1 regulates the sensitivity of GBM cells to TMZ. Our research will provide an important basis for future intensive molecular mechanism research in GBM and TMBIM1 might be a potential therapeutic target for treating GBM.

Glioblastoma multiforme (GBM) is the most common and most fatal primary malignant brain tumour in adults. The average survival time of patients after diagnosis is only 12–15 months. And its characteristics of excessive proliferation and apoptosis evasion play a crucial role in the poor prognosis of patients. Therefore, it is worth investigating the molecular mechanism of GBM to find an effective therapeutic target to overcome the dilemma. In the current study, Transmembrane BAX inhibitor motif containing 1 (TMBIM1) was highly expressed in GBM tissues and high TMBIM1 expression in GBM cell lines (U87 and U251) could promote cell proliferation and inhibit cell cycle arrest. In addition, TMBIM1 could significantly attenuate GBM cell apoptosis and decrease the sensitivity of GBM cells to temozolomide (TMZ). In terms of the molecular mechanism, we revealed that TMBIM1 interferes with the p38/MAPK pathway by inhibiting p38 phosphorylation to promote cell proliferation and attenuate cell apoptosis. In vivo experiments showed that the survival time of mice in TMBIM1 knockdown group was significantly prolonged. Our discovery provided an important basis for future intensive molecular mechanism research in GBM and presented a potential target for the treatment of GBM.

Risk Stratification for Early-Onset Colorectal Cancer Using a Combination of Genetic and Environmental Risk Scores: An International Multi-Center Study

BACKGROUND

The incidence of colorectal cancer (CRC) among individuals aged younger than 50 years has been increasing. As screening guidelines lower the recommended age of screening initiation, concerns including the burden on screening capacity and costs have been recognized, suggesting that an individualized approach may be warranted. We developed risk prediction models for early-onset CRC that incorporate an environmental risk score (ERS), including 16 lifestyle and environmental factors, and a polygenic risk score (PRS) of 141 variants.

METHODS

Relying on risk score weights for ERS and PRS derived from studies of CRC at all ages, we evaluated risks for early-onset CRC in 3486 cases and 3890 controls aged younger than 50 years. Relative and absolute risks for early-onset CRC were assessed according to values of the ERS and PRS. The discriminatory performance of these scores was estimated using the covariate-adjusted area under the receiver operating characteristic curve.

RESULTS

Increasing values of ERS and PRS were associated with increasing relative risks for early-onset CRC (odds ratio per SD of ERS = 1.14, 95% confidence interval [CI] = 1.08 to 1.20; odds ratio per SD of PRS = 1.59, 95% CI = 1.51 to 1.68), both contributing to case-control discrimination (area under the curve = 0.631, 95% CI = 0.615 to 0.647). Based on absolute risks, we can expect 26 excess cases per 10 000 men and 21 per 10 000 women among those scoring at the 90th percentile for both risk scores.

CONCLUSIONS

Personal risk scores have the potential to identify individuals at differential relative and absolute risk for early-onset CRC. Improved discrimination may aid in targeted CRC screening of younger, high-risk individuals, potentially improving outcomes.

Control of lysosomal-mediated cell death by the pH-dependent calcium channel RECS1

Programmed cell death is regulated by the balance between activating and inhibitory signals. Here, we have identified RECS1 (responsive to centrifugal force and shear stress 1) [also known as TMBIM1 (transmembrane BAX inhibitor motif containing 1)] as a proapoptotic member of the TMBIM family. In contrast to other proteins of the TMBIM family, RECS1 expression induces cell death through the canonical mitochondrial apoptosis pathway. Unbiased screening indicated that RECS1 sensitizes cells to lysosomal perturbations. RECS1 localizes to lysosomes, where it regulates their acidification and calcium content, triggering lysosomal membrane permeabilization. Structural modeling and electrophysiological studies indicated that RECS1 is a pH-regulated calcium channel, an activity that is essential to trigger cell death. RECS1 also sensitizes whole animals to stress in vivo in Drosophila melanogaster and zebrafish models. Our results unveil an unanticipated function for RECS1 as a proapoptotic component of the TMBIM family that ignites cell death programs at lysosomes.

Colorectal cancer risk susceptibility loci in a Swedish population

To search for colorectal cancer (CRC) risk loci, Swedish samples were used for a genome-wide haplotype analysis. A logistic regression model was employed in 2663 CRC cases and 1642 controls in the discovery analysis. Three analyses were done, on all, familial-, and nonfamilial CRC samples and only results with odds ratio (OR) > 1 were analyzed. single nucleotide polymorphism (SNP) analysis did not generate any statistically significant results. Haplotype analysis suggested novel loci, on chromosome 2q36.1 (OR = 1.71, p value = 5.6924 × 10^-8 ) in all CRC samples, chromosome 1q43 (OR = 4.04 p value = 3.24 × 10^-8 ) in familial CRC samples, and two hits in nonfamilial CRC samples, chromosomes 2q36.1 (OR = 1.71 p value = 5.69 × 10^-8 ) and 3p24.3 (OR = 1.62 p value = 6.21 × 10^-9 ). Moreover, one locus on chromosome 20q13.33 was suggested in analyses of all samples, and five more novel loci were suggested on chromosomes 10q25.3, 15q,22.31, 17p11.2, 1p34.2, and 3q24. The haplotypes from the analysis of all samples were replicated in a second study of CRC cases and controls from the same part of Sweden. In summary, using haplotype analysis in Swedish CRC samples, the best hits were novel loci and the locus on chromosomes 2q36.1 and 20q13.33 suggested in the analysis of all samples were confirmed in a second cohort. The ORs were often higher than ORs from published genome-wide association study (GWAS). The study suggested it was possible that a risk locus could involve more than one gene, and that haplotypes could give information on the gene or genes possibly involved in the risk at specific locus.

Repurposing non-invasive prenatal testing data: Population study of single nucleotide variants associated with colorectal cancer and Lynch syndrome

In our previous work, genomic data generated through non-invasive prenatal testing (NIPT) based on low-coverage massively parallel whole-genome sequencing of total plasma DNA of pregnant women in Slovakia was described as a valuable source of population specific data. In the present study, these data were used to determine the population allele frequency of common risk variants located in genes associated with colorectal cancer (CRC) and Lynch syndrome (LS). Allele frequencies of identified variants were compared with six world populations to detect significant differences between populations. Finally, variants were interpreted, functional consequences were searched for and clinical significance of variants was investigated using publicly available databases. Although the present study did not identify any pathogenic variants associated with CRC or LS in the Slovak population using NIPT data, significant differences were observed in the allelic frequency of risk CRC variants previously reported in genome-wide association studies and common variants located in genes associated with LS. As Slovakia is one of the leading countries with the highest incidence of CRC among male patients in the world, there is a need for studies dedicated to investigating the cause of such a high incidence of CRC in Slovakia. The present study also assumed that extensive cross-country data aggregation of NIPT results would represent an unprecedented source of information concerning human genome variation in cancer research.

Differential genetic influences over colorectal cancer risk and gene expression in large bowel mucosa

Site-specific variation in colorectal cancer (CRC) incidence, biology and prognosis are poorly understood. We sought to determine whether common genetic variants influencing CRC risk might exhibit topographical differences on CRC risk through regional differences in effects on gene expression in the large bowel mucosa. We conducted a site-specific genetic association study (10 630 cases, 31 331 controls) to identify whether established risk variants exert differential effects on risk of proximal, compared to distal CRC. We collected normal colorectal mucosa and blood from 481 subjects and assessed mucosal gene expression using Illumina HumanHT-12v4 arrays in relation to germline genotype. Expression quantitative trait loci (eQTLs) were explored by anatomical location of sampling. The rs3087967 genotype (chr11q23.1 risk variant) exhibited significant site-specific effects-risk of distal CRC (odds ratio [OR] = 1.20, P = 8.20 × 10-20 ) with negligible effects on proximal CRC risk (OR = 1.05, P = .10). Expression of 1261 genes differed between proximal and distal colonic mucosa (top hit PRAC gene, fold-difference = 10, P = 3.48 × 10-57 ). In eQTL studies, rs3087967 genotype was associated with expression of 8 cis- and 21 trans-genes. Four of these (AKAP14, ADH5P4, ASGR2, RP11-342M1.7) showed differential effects by site, with strongest trans-eQTL signals in proximal colonic mucosa (eg, AKAP14, beta = 0.61, P = 5.02 × 10-5 ) and opposite signals in distal mucosa (AKAP14, beta = -0.17, P = .04). In summary, genetic variation at the chr11q23.1 risk locus imparts greater risk of distal rather than proximal CRC and exhibits site-specific differences in eQTL effects in normal mucosa. Topographical differences in genomic control over gene expression relevant to CRC risk may underlie site-specific variation in CRC. Results may inform individualised CRC screening programmes.

Non-Lynch Familial and Early-Onset Colorectal Cancer Explained by Accumulation of Low-Risk Genetic Variants

A large proportion of familial and/or early-onset cancer patients do not carry pathogenic variants in known cancer predisposing genes. We aimed to assess the contribution of previously validated low-risk colorectal cancer (CRC) alleles to familial/early-onset CRC (fCRC) and to serrated polyposis. We estimated the association of CRC with a 92-variant-based weighted polygenic risk score (wPRS) using 417 fCRC patients, 80 serrated polyposis patients, 1077 hospital-based incident CRC patients, and 1642 controls. The mean wPRS was significantly higher in fCRC than in controls or sporadic CRC patients. fCRC patients in the highest (20th) wPRS quantile were at four-fold greater CRC risk than those in the middle quantile (10th). Compared to low-wPRS fCRC, a higher number of high-wPRS fCRC patients had developed multiple primary CRCs, had CRC family history, and were diagnosed at age ≥50. No association with wPRS was observed for serrated polyposis. In conclusion, a relevant proportion of mismatch repair (MMR)-proficient fCRC cases might be explained by the accumulation of low-risk CRC alleles. Validation in independent cohorts and development of predictive models that include polygenic risk score (PRS) data and other CRC predisposing factors will determine the implementation of PRS into genetic testing and counselling in familial and early-onset CRC.

Crohn's disease-associated ATG16L1 T300A genotype is associated with improved survival in gastric cancer

BACKGROUND

A non-synonymous single nucleotide polymorphism of the ATG16L1 gene, T300A, is a major Crohn's disease (CD) susceptibility allele, and is known to be associated with increased apoptosis induction in the small intestinal crypt base in CD subjects and mouse models. We hypothesized that ATG16L1 T300A genotype also correlates with increased tumor apoptosis and therefore could lead to superior clinical outcome in cancer subjects.

METHODS

T300A genotyping by Taqman assay was performed for gastric carcinoma subjects who underwent resection from two academic medical centers. Transcriptomic analysis was performed by RNA-seq on formalin-fixed paraffin-embedded cancerous tissue. Tumor apoptosis and autophagy were determined by cleaved caspase-3 and p62 immunohistochemistry, respectively. The subjects' genotypes were correlated with demographics, various histopathologic features, transcriptome, and clinical outcome.

FINDINGS

Of the 220 genotyped subjects, 163 (74%) subjects carried the T300A allele(s), including 55 (25%) homozygous and 108 (49%) heterozygous subjects. The T300A/T300A subjects had superior overall survival than the other groups. Their tumors were associated with increased CD-like lymphoid aggregates and increased tumor apoptosis without concurrent increase in tumor mitosis or defective autophagy. Transcriptomic analysis showed upregulation of WNT/β-catenin signaling and downregulation of PPAR, EGFR, and inflammatory chemokine pathways in tumors of T300A/T300A subjects.

INTERPRETATION

Gastric carcinoma of subjects with the T300A/T300A genotype is associated with repressed EGFR and PPAR pathways, increased tumor apoptosis, and improved overall survival. Genotyping gastric cancer subjects may provide additional insight for clinical stratification.

Prediction of colorectal cancer risk based on profiling with common genetic variants

Increasing numbers of common genetic variants associated with colorectal cancer (CRC) have been identified. Our study aimed to determine whether risk prediction based on common genetic variants might enable stratification for CRC risk. Meta-analysis of 11 genome-wide association studies comprising 16 871 cases and 26 328 controls was performed to capture CRC susceptibility variants. Genetic prediction models with several candidate polygenic risk scores (PRSs) were generated from Scottish CRC case-control studies (6478 cases and 11 043 controls) and the score with the best performance was then tested in UK Biobank (UKBB) (4800 cases and 20 287 controls). A weighted PRS of 116 CRC single nucleotide polymorphisms (wPRS116 ) was found with the best predictive performance, reporting a c-statistics of 0.60 and an odds ratio (OR) of 1.46 (95% confidence interval [CI] = 1.41-1.50, per SD increase) in Scottish data set. The predictive performance of this wPRS116 was consistently validated in UKBB data set with c-statistics of 0.61 and an OR of 1.49 (95% CI = 1.44-1.54, per SD increase). Modeling the levels of PRS with age and sex in the general UK population shows that employing genetic risk profiling can achieve a moderate degree of risk discrimination that could be helpful to identify a subpopulation with higher CRC risk due to genetic susceptibility.

Gene-environment interactions and colorectal cancer risk: An umbrella review of systematic reviews and meta-analyses of observational studies

The cause of colorectal cancer (CRC) is multifactorial, involving both genetic variants and environmental risk factors. We systematically searched the MEDLINE, EMBASE, China National Knowledge Infrastructure (CNKI) and Wanfang databases from inception to December 2016, to identify systematic reviews and meta-analyses of observational studies that investigated gene-environment (G×E) interactions in CRC risk. Then, we critically evaluated the cumulative evidence for the G×E interactions using an extension of the Human Genome Epidemiology Network's Venice criteria. Overall, 15 articles reporting systematic reviews of observational studies on 89 G×E interactions, 20 articles reporting meta-analyses of candidate gene- or single-nucleotide polymorphism-based studies on 521 G×E interactions, and 8 articles reporting 33 genome-wide G×E interaction analyses were identified. On the basis of prior and observed scores, only the interaction between rs6983267 (8q24) and aspirin use was found to have a moderate overall credibility score as well as main genetic and environmental effects. Though 5 other interactions were also found to have moderate evidence, these interaction effects were tenuous due to the lack of main genetic effects and/or environmental effects. We did not find highly convincing evidence for any interactions, but several associations were found to have moderate strength of evidence. Our conclusions are based on application of the Venice criteria which were designed to provide a conservative assessment of G×E interactions and thus do not include an evaluation of biological plausibility of an observed joint effect.

Mendelian randomisation: A powerful and inexpensive method for identifying and excluding non-genetic risk factors for colorectal cancer

Colorectal cancer (CRC) is the third most common cancer in economically developed countries and a major cause of cancer-related mortality. The importance of lifestyle and diet as major determinants of CRC risk is suggested by differences in CRC incidence between countries and in migration studies. Previous observational epidemiological studies have identified associations between modifiable environmental risk factors and CRC, but these studies can be susceptible to reverse causation and confounding, and their results can therefore conflict. Mendelian randomisation (MR) analysis represents an approach complementary to conventional observational studies examining associations between exposures and disease. The MR strategy employs allelic variants as instrumental variables (IVs), which act as proxies for non-genetic exposures. These allelic variants are randomly assigned during meiosis and can therefore inform on life-long exposure, whilst not being subject to reverse causation. In previous studies MR frameworks have associated several modifiable factors with CRC risk, including adiposity, hyperlipidaemia, fatty acid profile and alcohol consumption. In this review we detail the use of MR to investigate and discover CRC risk factors, and its future applications.

Genetic variant of TMBIM1 is associated with the susceptibility of colorectal cancer in the Chinese population

BACKGROUND AND AIMS

Recent meta-analysis of genome-wide association studies (GWASs) identified a novel variant rs992157 at 2q35 that was associated with colorectal cancer (CRC) in the population of European ancestry. We aimed to replicate the association of rs992157 with CRC in the Chinese population and to further determine the real susceptible gene of CRC as indicated by this variant.

METHODS

824 CRC patients and 1063 healthy controls were included. The frequency of the genotype and the allele of rs992157 were compared between the patients and the controls and between different subgroups of patients classified by status of metastasis. Expression level of TMBIM1 was compared between the tumor tissue and the adjacent normal tissues collected from 43 patients during surgery. Besides, the relationship between genotypes of rs992157 and the tissue expression of TMBIM1 was analyzed.

RESULTS

Patients were found to have significantly higher frequency of allele G than the controls (44.2% vs. 40.0%, P = 0.009; OR = 1.18). Moreover, allele G was associated with an increased risk of lymph node metastasis (P = 0.02) and distant metastasis of CRC (P = 0.04). The mean expression level of TMBIM1 was significantly higher in tumor tissue than in the adjacent normal tissues (0.0019 ± 0.00068 vs. 0.00041 ± 0.00024, P < 0.001). In addition, patients with genotype GG were found to have remarkably higher TMBIM1 expression in the tumors than those with genotype AA (0.0024 ± 0.00052 vs. 0.0015 ± 0.00078, P = 0.005).

CONCLUSION

Variant rs992157 is significantly associated with the susceptibility and progression of CRC. It can increase the risk of CRC possibly via up-regulation of TMBIM1.

Association analyses identify 31 new risk loci for colorectal cancer susceptibility

Colorectal cancer (CRC) is a leading cause of cancer-related death worldwide, and has a strong heritable basis. We report a genome-wide association analysis of 34,627 CRC cases and 71,379 controls of European ancestry that identifies SNPs at 31 new CRC risk loci. We also identify eight independent risk SNPs at the new and previously reported European CRC loci, and a further nine CRC SNPs at loci previously only identified in Asian populations. We use in situ promoter capture Hi-C (CHi-C), gene expression, and in silico annotation methods to identify likely target genes of CRC SNPs. Whilst these new SNP associations implicate target genes that are enriched for known CRC pathways such as Wnt and BMP, they also highlight novel pathways with no prior links to colorectal tumourigenesis. These findings provide further insight into CRC susceptibility and enhance the prospects of applying genetic risk scores to personalised screening and prevention.

Systematic evaluation of cancer-specific genetic risk score for 11 types of cancer in The Cancer Genome Atlas and Electronic Medical Records and Genomics cohorts

BACKGROUND

Genetic risk score (GRS) is an odds ratio (OR)-weighted and population-standardized method for measuring cumulative effect of multiple risk-associated single nucleotide polymorphisms (SNPs). We hypothesize that GRS is a valid tool for risk assessment of most common cancers.

METHODS

Utilizing genotype and phenotype data from The Cancer Genome Atlas (TCGA) and Electronic Medical Records and Genomics (eMERGE), we tested 11 cancer-specific GRSs (bladder, breast, colorectal, glioma, lung, melanoma, ovarian, pancreatic, prostate, renal, and thyroid cancer) for association with the respective cancer type. Cancer-specific GRSs were calculated, for the first time in these cohorts, based on previously published risk-associated SNPs using the Caucasian subjects in these two cohorts.

RESULTS

Mean cancer-specific GRS in the population controls of eMERGE approximated the expected value of 1.00 (between 0.98 and 1.02) for all 11 types of cancer. Mean cancer-specific GRS was consistently higher in respective cancer patients than controls for all 11 types of cancer (P < 0.05). When subjects were categorized into low-, average-, and high-risk groups based on cancer-specific GRS (<0.5, 0.5-1.5, and >1.5, respectively), significant dose-response associations of higher cancer-specific GRS with higher OR of respective type of cancer were found for nine types of cancer (P_-trend  < 0.05). More than 64% subjects in the population controls of eMERGE can be classified as high risk for at least one type of these cancers.

CONCLUSION

Validity of GRS for predicting cancer risk is demonstrated for most types of cancer. If confirmed in larger studies, cancer-specific GRS may have the potential for developing personalized cancer screening strategy.

Genetic variant predictors of gene expression provide new insight into risk of colorectal cancer

Genome-wide association studies have reported 56 independently associated colorectal cancer (CRC) risk variants, most of which are non-coding and believed to exert their effects by modulating gene expression. The computational method PrediXcan uses cis-regulatory variant predictors to impute expression and perform gene-level association tests in GWAS without directly measured transcriptomes. In this study, we used reference datasets from colon (n = 169) and whole blood (n = 922) transcriptomes to test CRC association with genetically determined expression levels in a genome-wide analysis of 12,186 cases and 14,718 controls. Three novel associations were discovered from colon transverse models at FDR ≤ 0.2 and further evaluated in an independent replication including 32,825 cases and 39,933 controls. After adjusting for multiple comparisons, we found statistically significant associations using colon transcriptome models with TRIM4 (discovery P = 2.2 × 10- 4, replication P = 0.01), and PYGL (discovery P = 2.3 × 10- 4, replication P = 6.7 × 10- 4). Interestingly, both genes encode proteins that influence redox homeostasis and are related to cellular metabolic reprogramming in tumors, implicating a novel CRC pathway linked to cell growth and proliferation. Defining CRC risk regions as one megabase up- and downstream of one of the 56 independent risk variants, we defined 44 non-overlapping CRC-risk regions. Among these risk regions, we identified genes associated with CRC (P < 0.05) in 34/44 CRC-risk regions. Importantly, CRC association was found for two genes in the previously reported 2q25 locus, CXCR1 and CXCR2, which are potential cancer therapeutic targets. These findings provide strong candidate genes to prioritize for subsequent laboratory follow-up of GWAS loci. This study is the first to implement PrediXcan in a large colorectal cancer study and findings highlight the utility of integrating transcriptome data in GWAS for discovery of, and biological insight into, risk loci.

Novel Common Genetic Susceptibility Loci for Colorectal Cancer

BACKGROUND

Previous genome-wide association studies (GWAS) have identified 42 loci (P < 5 × 10-8) associated with risk of colorectal cancer (CRC). Expanded consortium efforts facilitating the discovery of additional susceptibility loci may capture unexplained familial risk.

METHODS

We conducted a GWAS in European descent CRC cases and control subjects using a discovery-replication design, followed by examination of novel findings in a multiethnic sample (cumulative n = 163 315). In the discovery stage (36 948 case subjects/30 864 control subjects), we identified genetic variants with a minor allele frequency of 1% or greater associated with risk of CRC using logistic regression followed by a fixed-effects inverse variance weighted meta-analysis. All novel independent variants reaching genome-wide statistical significance (two-sided P < 5 × 10-8) were tested for replication in separate European ancestry samples (12 952 case subjects/48 383 control subjects). Next, we examined the generalizability of discovered variants in East Asians, African Americans, and Hispanics (12 085 case subjects/22 083 control subjects). Finally, we examined the contributions of novel risk variants to familial relative risk and examined the prediction capabilities of a polygenic risk score. All statistical tests were two-sided.

RESULTS

The discovery GWAS identified 11 variants associated with CRC at P < 5 × 10-8, of which nine (at 4q22.2/5p15.33/5p13.1/6p21.31/6p12.1/10q11.23/12q24.21/16q24.1/20q13.13) independently replicated at a P value of less than .05. Multiethnic follow-up supported the generalizability of discovery findings. These results demonstrated a 14.7% increase in familial relative risk explained by common risk alleles from 10.3% (95% confidence interval [CI] = 7.9% to 13.7%; known variants) to 11.9% (95% CI = 9.2% to 15.5%; known and novel variants). A polygenic risk score identified 4.3% of the population at an odds ratio for developing CRC of at least 2.0.

CONCLUSIONS

This study provides insight into the architecture of common genetic variation contributing to CRC etiology and improves risk prediction for individualized screening.

Discovery of common and rare genetic risk variants for colorectal cancer

To further dissect the genetic architecture of colorectal cancer (CRC), we performed whole-genome sequencing of 1,439 cases and 720 controls, imputed discovered sequence variants and Haplotype Reference Consortium panel variants into genome-wide association study data, and tested for association in 34,869 cases and 29,051 controls. Findings were followed up in an additional 23,262 cases and 38,296 controls. We discovered a strongly protective 0.3% frequency variant signal at CHD1. In a combined meta-analysis of 125,478 individuals, we identified 40 new independent signals at P < 5 × 10-8, bringing the number of known independent signals for CRC to ~100. New signals implicate lower-frequency variants, Krüppel-like factors, Hedgehog signaling, Hippo-YAP signaling, long noncoding RNAs and somatic drivers, and support a role for immune function. Heritability analyses suggest that CRC risk is highly polygenic, and larger, more comprehensive studies enabling rare variant analysis will improve understanding of biology underlying this risk and influence personalized screening strategies and drug development.

Up regulated Tmbim1 activation promotes high fat diet (HFD)-induced cardiomyopathy by enhancement of inflammation and oxidative stress

The prevalence of cardiomyopathy due to metabolic stress has up-regulated dramatically; nevertheless, its molecular mechanisms remain unclear. Here we suggested that transmembrane BAX inhibitor motif-containing 1 (Tmbim1) is down-regulated in the hearts of mice fed with high fat diet (HFD). We provided evidence that Tmbim1 knockout (KO) accelerated HFD-induced metabolic disorders in mice, as supported by the remarkable increase of fasting serum glucose and insulin levels. HFD-induced cardiac dysfunctions were greatly intensified by the loss of Tmbim1, along with higher levels of lactate dehydrogenase (LDH) and creatine kinase (CK) in serum. In addition, Tmbim1 deletion significantly enhanced lipid accumulation in heart of mice administrated with HFD. Furthermore, Tmbim1 knockout reinforced myocardial inflammation, evidenced by increasing the expression of pro-inflammatory cytokines (interleukin 1β (IL-1β), IL-6 and tumor necrosis factor-α (TNF-α)), and the activation of nuclear factor-κB (NF-κB) signaling pathway. Tmbim1 deficiency strengthened oxidative damage in hearts of HFD-fed mice, accompanied with a significant reduction of nuclear factor-erythroid 2 related factor 2 (Nrf-2) pathway. In palmitate (PA)-treated primary cardiomyocytes, Tmbim1 ablation markedly enhanced cell inflammation and oxidative stress, which were abolished by the suppression of ROS generation and NF-κB activation. Taken together, these findings suggested that Tmbim1 might be a key suppressor of metabolic stress-induced cardiomyopathy, which could be a promising target for the treatment of metabolic syndrome-triggered myocardial damage and heart failure.

Exploring causality in the association between circulating 25-hydroxyvitamin D and colorectal cancer risk: a large Mendelian randomisation study

BACKGROUND

Whilst observational studies establish that lower plasma 25-hydroxyvitamin D (25-OHD) levels are associated with higher risk of colorectal cancer (CRC), establishing causality has proven challenging. Since vitamin D is modifiable, these observations have substantial clinical and public health implications. Indeed, many health agencies already recommend supplemental vitamin D. Here, we explore causality in a large Mendelian randomisation (MR) study using an improved genetic instrument for circulating 25-OHD.

METHODS

We developed a weighted genetic score for circulating 25-OHD using six genetic variants that we recently reported to be associated with circulating 25-OHD in a large genome-wide association study (GWAS) meta-analysis. Using this score as instrumental variable in MR analyses, we sought to determine whether circulating 25-OHD is causally linked with CRC risk. We conducted MR analysis using individual-level data from 10,725 CRC cases and 30,794 controls (Scotland, UK Biobank and Croatia). We then applied estimates from meta-analysis of 11 GWAS of CRC risk (18,967 cases; 48,168 controls) in a summary statistics MR approach.

RESULTS

The new genetic score for 25-OHD was strongly associated with measured plasma 25-OHD levels in 2821 healthy Scottish controls (P = 1.47 × 10- 11), improving upon previous genetic instruments (F-statistic 46.0 vs. 13.0). However, individual-level MR revealed no association between 25-OHD score and CRC risk (OR 1.03/unit log-transformed circulating 25-OHD, 95% CI 0.51-2.07, P = 0.93). Similarly, we found no evidence for a causal relationship between 25-OHD and CRC risk using summary statistics MR analysis (OR 0.91, 95% CI 0.69-1.19, P = 0.48).

CONCLUSIONS

Despite the scale of this study and employing an improved score capturing more of the genetic contribution to circulating 25-OHD, we found no evidence for a causal relationship between circulating 25-OHD and CRC risk. Although the magnitude of effect for vitamin D suggested by observational studies can confidently be excluded, smaller effects sizes and non-linear relationships remain plausible. Circulating vitamin D may be a CRC biomarker, but a causal effect on CRC risk remains unproven.

Association of LACC1, CEBPB-PTPN1, RIPK2 and ADO-EGR2 with ocular Behcet's disease in a Chinese Han population

Background

An Immunochip study recently identified the association of a number of new genetic loci with Behcet’s disease (BD).

Objective

To confirm the association between new genetic loci reported in an Immunochip study and BD in a Han Chinese population.

Methods

A two-stage association study was carried out in 1238 patients with BD and 1458 healthy controls. Twenty-two candidate single nucleotide polymorphisms (SNPs) were selected for genotyping by iPLEXGold genotyping or TaqMan SNP assays and a meta-analysis was performed for significantly associated markers.

Results

The results showed that four SNPs (LACC1/rs9316059, CEBPB-PTPN1/rs913678, ADO-EGR2/rs224127 and RIPK2/rs10094579) were associated with BD in an allelic association test (rs9316059 T allele: p_c=4.95×10⁻⁸, OR=0.687; rs913678 C allele: p_c=3.01×10⁻⁴, OR=1.297; rs224127 A allele: p_c=3.77×10⁻⁴, OR=1.274; rs10094579 A allele: p_c=6.93×10⁻⁴, OR=1.302). For four SNPs tested by meta-analysis, the association with BD was strengthened and all exceeded genome-wide significance (rs9316059: p=2.96×10⁻¹⁶; rs913678: p=2.09×10⁻¹⁶; rs224127: p=5.28×10⁻¹³; rs10094579: p=9.21×10⁻¹¹).

Conclusions

Our findings confirmed the association of four loci (LACC1, CEBPB-PTPN1, ADO-EGR2 and RIPK2) in Chinese Han patients with BD.

Golgi anti-apoptotic protein: a tale of camels, calcium, channels and cancer

Golgi anti-apoptotic protein (GAAP), also known as transmembrane Bax inhibitor-1 motif-containing 4 (TMBIM4) or Lifeguard 4 (Lfg4), shares remarkable amino acid conservation with orthologues throughout eukaryotes, prokaryotes and some orthopoxviruses, suggesting a highly conserved function. GAAPs regulate Ca²⁺ levels and fluxes from the Golgi and endoplasmic reticulum, confer resistance to a broad range of apoptotic stimuli, promote cell adhesion and migration via the activation of store-operated Ca²⁺ entry, are essential for the viability of human cells, and affect orthopoxvirus virulence. GAAPs are oligomeric, multi-transmembrane proteins that are resident in Golgi membranes and form cation-selective ion channels that may explain the multiple functions of these proteins. Residues contributing to the ion-conducting pore have been defined and provide the first clues about the mechanistic link between these very different functions of GAAP. Although GAAPs are naturally oligomeric, they can also function as monomers, a feature that distinguishes them from other virus-encoded ion channels that must oligomerize for function. This review summarizes the known functions of GAAPs and discusses their potential importance in disease.

Genome-wide association study and meta-analysis in Northern European populations replicate multiple colorectal cancer risk loci

Genome-wide association studies have been successful in elucidating the genetic basis of colorectal cancer (CRC), but there remains unexplained variability in genetic risk. To identify new risk variants and to confirm reported associations, we conducted a genome-wide association study in 1,701 CRC cases and 14,082 cancer-free controls from the Finnish population. A total of 9,068,015 genetic variants were imputed and tested, and 30 promising variants were studied in additional 11,647 cases and 12,356 controls of European ancestry. The previously reported association between the single-nucleotide polymorphism (SNP) rs992157 (2q35) and CRC was independently replicated (p = 2.08 × 10-4 ; OR, 1.14; 95% CI, 1.06-1.23), and it was genome-wide significant in combined analysis (p = 1.50 × 10-9 ; OR, 1.12; 95% CI, 1.08-1.16). Variants at 2q35, 6p21.2, 8q23.3, 8q24.21, 10q22.3, 10q24.2, 11q13.4, 11q23.1, 14q22.2, 15q13.3, 18q21.1, 20p12.3 and 20q13.33 were associated with CRC in the Finnish population (false discovery rate < 0.1), but new risk loci were not found. These results replicate the effects of multiple loci on the risk of CRC and identify shared risk alleles between the Finnish population isolate and outbred populations.

Risk of colorectal polyps and of malignancies in asymptomatic carriers of mutations in the main DNA mismatch repair genes

OBJECTIVE

Mutation carriers (Mut+) in DNA mismatch repair genes are predisposed to cancer of various organs and to adenomatous polyps; however, they may remain asymptomatic and cancer or polyp-free for several years. We purposed to analyse the clinical follow-up of individuals carrying constitutional mutations in the MLH1, MSH2 or MSH6 genes who were unaffected by benign polyps or malignant tumours at diagnosis.

MATERIAL AND METHODS

Mut + subjects (n.81) were members of Lynch syndromes in whom mutations were detected between 1993 and 2015; all were asymptomatic at diagnosis. They were informed of the cancer risk and surveillance was suggested. As controls, 113 nongene carriers (Mut-) in the same Lynch families were identified.

RESULTS

About one-fourth of the mutation carriers developed polyps, mostly adenomas; polyps were less (12%, p < .05) in Mut - subjects, and hyperplastic lesions were the prevalent histology. More polyps were detected in MLH1 vs. MSH2 mutation carriers. In Mut+, 21 malignant tumours developed in 14 carriers vs. 4 tumours in 3 patients among Mut- (p < .001). Tumours were mostly of the Lynch spectrum; however, three glioblastomas were developed, together with neoplasms of various organs (duodenum, thyroid, skin, lung and cervix). Mean age of tumour occurrence was 43.0 years in Mut + vs. 53.0 among Mut-.

CONCLUSIONS

Cancer developed more often in Mut+, with no consistent difference between MLH1 and MSH2 carriers. More polyps (mostly adenomas) were detected in MLH1 carriers. The majority (13 of 21) of malignant tumours occurred in organs for which there is no recommended surveillance, and were lethal in three patients.

Genome-wide association studies of cancer: current insights and future perspectives

Genome-wide association studies (GWAS) provide an agnostic approach for investigating the genetic basis of complex diseases. In oncology, GWAS of nearly all common malignancies have been performed, and over 450 genetic variants associated with increased risks have been identified. As well as revealing novel pathways important in carcinogenesis, these studies have shown that common genetic variation contributes substantially to the heritable risk of many common cancers. The clinical application of GWAS is starting to provide opportunities for drug discovery and repositioning as well as for cancer prevention. However, deciphering the functional and biological basis of associations is challenging and is in part a barrier to fully unlocking the potential of GWAS.

Pro-inflammatory fatty acid profile and colorectal cancer risk: A Mendelian randomisation analysis

BACKGROUND

While dietary fat has been established as a risk factor for colorectal cancer (CRC), associations between fatty acids (FAs) and CRC have been inconsistent. Using Mendelian randomisation (MR), we sought to evaluate associations between polyunsaturated (PUFA), monounsaturated (MUFA) and saturated FAs (SFAs) and CRC risk.

METHODS

We analysed genotype data on 9254 CRC cases and 18,386 controls of European ancestry. Externally weighted polygenic risk scores were generated and used to evaluate associations with CRC per one standard deviation increase in genetically defined plasma FA levels.

RESULTS

Risk reduction was observed for oleic and palmitoleic MUFAs (OROA = 0.77, 95% CI: 0.65-0.92, P = 3.9 × 10-3; ORPOA = 0.36, 95% CI: 0.15-0.84, P = 0.018). PUFAs linoleic and arachidonic acid had negative and positive associations with CRC respectively (ORLA = 0.95, 95% CI: 0.93-0.98, P = 3.7 × 10-4; ORAA = 1.05, 95% CI: 1.02-1.07, P = 1.7 × 10-4). The SFA stearic acid was associated with increased CRC risk (ORSA = 1.17, 95% CI: 1.01-1.35, P = 0.041).

CONCLUSION

Results from our analysis are broadly consistent with a pro-inflammatory FA profile having a detrimental effect in terms of CRC risk.

Evaluation of genetic variants in association with colorectal cancer risk and survival in Asians

Genome-wide association studies (GWAS) have identified over 40 genetic loci associated with colorectal cancer (CRC) risk. The association of single nucleotide polymorphisms (SNPs) at these loci with CRC risk and survival has not been adequately evaluated in East Asians. GWAS-identified CRC risk variants were used to construct weighted genetic risk scores (GRSs). We evaluated these GRSs in association with CRC risk in 3,303 CRC cases and 3,553 controls using logistic regression models. Associations with overall and CRC-specific survival were assessed in 731 CRC patients using Cox regression models. The association between the GRSs (overall and Asian-specific) and CRC risk was approximately twofold (highest vs. lowest quintile), and the shape of the dose-response was linear (ptrend  = 1.24 × 10-13 and 3.02 × 10-14 for overall GRS and Asian-specific GRS, respectively). The association of the GRS with CRC risk was stronger among those with a family history of CRC (pinteraction  = 0.007). Asian-specific GRS using previously reported survival SNPs increased risk for mortality and the shape of the dose-response was linear for CRC-specific and all-cause mortality (ptrend  = 0.01 and 0.006, respectively). Furthermore, the minor alleles of rs6983267 and rs1957636 were associated with worse CRC-specific and overall survival. We show that GRSs constructed using GWAS-identified common variants are strongly associated with CRC risk in Asians. We confirm previous findings for the possible association between some SNPs with survival, and provide evidence for two additional CRC risk variants that may be related to CRC survival.

Mendelian randomisation implicates hyperlipidaemia as a risk factor for colorectal cancer

While elevated blood cholesterol has been associated with an increased risk of colorectal cancer (CRC) in observational studies, causality is uncertain. Here we apply a Mendelian randomisation (MR) analysis to examine the potential causal relationship between lipid traits and CRC risk. We used single nucleotide polymorphisms (SNPs) associated with blood levels of total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL), and high-density lipoprotein (HDL) as instrumental variables (IV). We calculated MR estimates for each risk factor with CRC using SNP-CRC associations from 9,254 cases and 18,386 controls. Genetically predicted higher TC was associated with an elevated risk of CRC (odds ratios (OR) per unit SD increase = 1.46, 95% confidence interval [CI]: 1.20-1.79, p = 1.68 × 10-4 ). The pooled ORs for LDL, HDL, and TG were 1.05 (95% CI: 0.92-1.18, p = 0.49), 0.94 (95% CI: 0.84-1.05, p = 0.27), and 0.98 (95% CI: 0.85-1.12, p = 0.75) respectively. A genetic risk score for 3-hydoxy-3-methylglutaryl-coenzyme A reductase (HMGCR) to mimic the effects of statin therapy was associated with a reduced CRC risk (OR = 0.69, 95% CI: 0.49-0.99, p = 0.046). This study supports a causal relationship between higher levels of TC with CRC risk, and a further rationale for implementing public health strategies to reduce the prevalence of hyperlipidaemia.

Mendelian randomisation analysis strongly implicates adiposity with risk of developing colorectal cancer

BACKGROUND

Observational studies have associated adiposity with an increased risk of colorectal cancer (CRC). However, such studies do not establish a causal relationship. To minimise bias from confounding we performed a Mendelian randomisation (MR) analysis to examine the relationship between adiposity and CRC.

METHODS

We used SNPs associated with adult body mass index (BMI), waist-hip ratio (WHR), childhood obesity and birth weight as instrumental variables in a MR analysis of 9254 CRC cases and 18 386 controls.

RESULTS

In the MR analysis, the odds ratios (ORs) of CRC risk per unit increase in BMI, WHR and childhood obesity were 1.23 (95% CI: 1.02-1.49, P=0.033), 1.59 (95% CI: 1.08-2.34, P=0.019) and 1.07 (95% CI: 1.03-1.13, P=0.018), respectively. There was no evidence for association between birth weight and CRC (OR=1.22, 95% CI: 0.89-1.67, P=0.22). Combining these data with a concurrent MR-based analysis for BMI and WHR with CRC risk (totalling to 18 190 cases, 27 617 controls) provided increased support, ORs for BMI and WHR were 1.26 (95% CI: 1.10-1.44, P=7.7 × 10(-4)) and 1.40 (95% CI: 1.14-1.72, P=1.2 × 10(-3)), respectively.

CONCLUSIONS

These data provide further evidence for a strong causal relationship between adiposity and the risk of developing CRC highlighting the urgent need for prevention and treatment of adiposity.