Effects of interactions between common genetic variants and smoking on colorectal cancer

Smoking as a risk factor for colorectal neoplasms in young individuals? A systematic meta-analysis

BACKGROUND AND AIMS

Early-onset colorectal neoplasms (EoCRN) include both benign and malign colorectal tumors, which occur before the age of 50. The incidence of EoCRN is rising worldwide. Tobacco smoking has previously been proven to be related to the development of various tumor types. However, its relationship with EoCRN is not clearly defined. Hence, we carried out a systematic review and a meta-analysis to evaluate the relationship between smoking status and the risk of EoCRN.

METHODS

A systematic search of PubMed, EMBASE, and Web of Science up to September 7, 2022, was performed for studies that evaluated the association of smoking status with EoCRN. The quality of the case-control study was evaluated with the Newcastle‒Ottawa Scale. The quality of the cross-sectional studies was evaluated with the American Health Care Research and Quality checklist. Fixed-effects models were used to pool odds ratios (ORs) to evaluate the relationship between the risk of developing EoCRN and smoking status. The meta-analyses were performed with Review Manager version 5.4, and funnel plots and publication bias tests were produced by STATA software.

RESULTS

A total of six studies were included in this meta-analysis. After pooling the results of these six studies, we found that current smokers carry a relatively high risk of developing EoCRN (OR, 1.33; 95% confidence interval [CI], 1.17-1.52) compared to never-smokers. Ex-smokers were not at a significantly increased risk for developing EoCRN (OR, 1.00; 95% CI, 0.86-1.18).

DISCUSSION

Smoking behavior is significantly associated with an increased risk for developing EoCRN and might be one of the reasons for the increasing incidence. Ex-smokers who quit are not at significant risk of developing EoCRN.

Global burden of cancers attributable to tobacco smoking, 1990-2019: an ecological study

Aim and background

Identifying risk factors for cancer initiation and progression is the cornerstone of the preventive approach to cancer management and control (EPMA J. 4(1):6, 2013). Tobacco smoking is a well-recognized risk factor for initiation and spread of several cancers. The predictive, preventive, and personalized medicine (PPPM) approach to cancer management and control focuses on smoking cessation as an essential cancer prevention strategy. Towards this end, this study examines the temporal patterns of cancer burden due to tobacco smoking in the last three decades at global, regional, and national levels.

Data and methods

The data pertaining to the burden of 16 cancers attributable to tobacco smoking at global, regional, and national levels were procured from the Global Burden of Disease 2019 Study. Two main indicators, deaths and disability-adjusted life years (DALYs), were used to describe the burden of cancers attributable to tobacco smoking. The socio-economic development of countries was measured using the socio-demographic index (SDI).

Results

Globally, deaths due to neoplasms caused by tobacco smoking increased from 1.5 million in 1990 to 2.5 million in 2019, whereas the age-standardized mortality rate (ASMR) decreased from 39.8/100,000 to 30.6/100,000 and the age-standardized DALY rate (ASDALR) decreased from 948.9/100,000 to 677.3/100,000 between 1990 and 2019. Males accounted for approximately 80% of global deaths and DALYs in 2019. Populous regions of Asia and a few regions of Europe account for the largest absolute burden, whereas countries in Europe and America have the highest age-standardized rates of cancers due to tobacco smoking. In 8 out of 21 regions, there were more than 100,000 deaths due to cancers attributable to tobacco smoking led by East Asia, followed by Western Europe in 2019. The regions of Sub-Saharan Africa (except southern region) had one of the lowest absolute counts of deaths, DALYs, and age-standardized rates. In 2019, tracheal, bronchus, and lung (TBL), esophageal, stomach, colorectal, and pancreatic cancer were the top 5 neoplasms attributable to tobacco smoking, with different burdens in regions as per their development status. The ASMR and ASDALR of neoplasms due to tobacco smoking were positively correlated with SDI, with pairwise correlation coefficient of 0.55 and 0.52, respectively.

Conclusion

As a preventive tool, tobacco smoking cessation has the biggest potential among all risk factors for preventing millions of cancer deaths every year. Cancer burden due to tobacco smoking is found to be higher in males and is positively associated with socio-economic development of countries. As tobacco smoking begins mostly at younger ages and the epidemic is unfolding in several parts of the world, more accelerated efforts are required towards tobacco cessation and preventing youth from entering this addiction. The PPPM approach to medicine suggests that not only personalized and precision medicine must be provided to cancer patients afflicted by tobacco smoking but personalized and targeted preventive solutions must be provided to prevent initiation and progression of smoking.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13167-022-00308-y.

GMEPS: a fast and efficient likelihood approach for genome-wide mediation analysis under extreme phenotype sequencing

Due to many advantages such as higher statistical power of detecting the association of genetic variants in human disorders and cost saving, extreme phenotype sequencing (EPS) is a rapidly emerging study design in epidemiological and clinical studies investigating how genetic variations associate with complex phenotypes. However, the investigation of the mediation effect of genetic variants on phenotypes is strictly restrictive under the EPS design because existing methods cannot well accommodate the non-random extreme tails sampling process incurred by the EPS design. In this paper, we propose a likelihood approach for testing the mediation effect of genetic variants through continuous and binary mediators on a continuous phenotype under the EPS design (GMEPS). Besides implementing in EPS design, it can also be utilized as a general mediation analysis procedure. Extensive simulations and two real data applications of a genome-wide association study of benign ethnic neutropenia under EPS design and a candidate-gene study of neurocognitive performance in patients with sickle cell disease under random sampling design demonstrate the superiority of GMEPS under the EPS design over widely used mediation analysis procedures, while demonstrating compatible capabilities under the general random sampling framework.

Smoking, Genetic Predisposition, and Colorectal Cancer Risk

INTRODUCTION

Smoking and genetic predisposition are established risk factors for colorectal cancer (CRC). We aimed to assess and compare their individual and joint impact on CRC risk using the novel approach of genetic risk equivalent (GRE).

METHODS

Data were extracted from the Darmkrebs: Chancen der Verhütung durch Screening study, a large population-based case-control study in Germany. A polygenic risk score (PRS) based on 140 CRC-related single nucleotide polymorphisms was derived to quantify genetic risk. Multiple logistic regression was used to estimate the individual and joint impact of smoking and PRS on CRC risk, and to quantify the smoking effect in terms of GRE, the corresponding effect conveyed by a defined difference in PRS percentiles.

RESULTS

There were 5,086 patients with CRC and 4,120 controls included. Current smokers had a 48% higher risk of CRC than never smokers (adjusted odds ratio 1.48, 95% confidence interval 1.27-1.72). A PRS above the 90th percentile was significantly associated with a 3.6-, 4.3-, and 6.4-fold increased risk of CRC in never, former, and current smokers, respectively, when compared with a PRS below the 10th percentile in never smokers. The interaction between smoking and PRS on CRC risk did not reach statistical significance (P = 0.53). The effect of smoking was equivalent to the effect of having a 30 percentile higher level of PRS (GRE 30, 95% confidence interval 18-42).

DISCUSSION

Both smoking and the PRS carry essentially independent CRC risk information, and their joint consideration provides powerful risk stratification. Abstinence from smoking can compensate for a substantial proportion of genetically determined CRC risk.

Risk factors for ulcerative colitis-associated colorectal cancer: A retrospective cohort study

Inflammatory bowel disease is associated with an increased risk of colorectal cancer. The study aims to identify the risk factors for ulcerative colitis-colorectal cancer and to perform a survival curve analysis of the outcome.This retrospective cohort study included 254 patients from March 2016 to October 2017. Age, age at diagnosis, follow-up time, smoking status, and family history of colorectal cancer were analyzed as risk factors for colorectal cancer.The mean patient age was 46.6 ± 16.9 years; 5.5% of the patients were smokers and 49.6% had pancolitis. Six patients (2.36%) had colorectal cancer, which was associated with age at diagnosis (odds/hazard ratio 1.059 [95% confidence interval: 1.001-1.121]; P = .04), family history of colorectal cancer (12.992 [1.611-104.7]; P = .02), and follow-up time (0.665 [0.513-0.864]; P = .002). Active smoking was the main identified risk factor, after both logistic (8.477 [1.350-53.232]; P = .02) and Cox proportional-hazards (32.484 [2.465-428.1]; P = .008) regression analysis. The risk of colorectal cancer was 3.17% at 10 years and 4.26% at 20 years of follow-up.Active smoking and family history were identified as risk factors for colorectal cancer. These findings should aid the early identification of patients who require vigorous surveillance, and prevent exposure to risk factors.

Metabolic models predict bacterial passengers in colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is a complex multifactorial disease. Increasing evidence suggests that the microbiome is involved in different stages of CRC initiation and progression. Beyond specific pro-oncogenic mechanisms found in pathogens, metagenomic studies indicate the existence of a microbiome signature, where particular bacterial taxa are enriched in the metagenomes of CRC patients. Here, we investigate to what extent the abundance of bacterial taxa in CRC metagenomes can be explained by the growth advantage resulting from the presence of specific CRC metabolites in the tumor microenvironment.

METHODS

We composed lists of metabolites and bacteria that are enriched on CRC samples by reviewing metabolomics experimental literature and integrating data from metagenomic case-control studies. We computationally evaluated the growth effect of CRC enriched metabolites on over 1500 genome-based metabolic models of human microbiome bacteria. We integrated the metabolomics data and the mechanistic models by using scores that quantify the response of bacterial biomass production to CRC-enriched metabolites and used these scores to rank bacteria as potential CRC passengers.

RESULTS

We found that metabolic networks of bacteria that are significantly enriched in CRC metagenomic samples either depend on metabolites that are more abundant in CRC samples or specifically benefit from these metabolites for biomass production. This suggests that metabolic alterations in the cancer environment are a major component shaping the CRC microbiome.

CONCLUSION

Here, we show with in sillico models that supplementing the intestinal environment with CRC metabolites specifically predicts the outgrowth of CRC-associated bacteria. We thus mechanistically explain why a range of CRC passenger bacteria are associated with CRC, enhancing our understanding of this disease. Our methods are applicable to other microbial communities, since it allows the systematic investigation of how shifts in the microbiome can be explained from changes in the metabolome.

Evaluation of gene-environment interactions for colorectal cancer susceptibility loci using case-only and case-control designs

BACKGROUND

Genome-wide association studies (GWAS) have identified more than 40 colorectal cancer susceptibility loci, but only a small fraction of heritability was explained. To account for missing heritability, we investigated gene-environment interactions (G × Es) between GWAS-identified single-nucleotide polymorphisms (SNPs) and established risk or protective factors for colorectal cancer using both case-only and case-control study designs.

METHODS

Data on 703 colorectal cancer cases and 1406 healthy controls from the National Cancer Center in Korea were used. We tested interactions between 31 GWAS-identified SNPs and 13 established risk or protective factors for colorectal cancer (family history, body mass index, history of colorectal polyps, inflammatory bowel disease, and diabetes mellitus, alcohol drinking, smoking, regular exercise, regular aspirin use, postmenopausal hormone replace therapy, red meat and processed meat intake, and dairy consumption). Logistic regression models were used to assess G × Es for colorectal cancer risk.

RESULTS

The SNP rs4444235 at 14q22.2 interacted with regular exercise in colorectal cancer (p_case-only = 2.4 × 10^- 3, p_case-control = 1.5 × 10^- 3). The risk allele (C) of rs4444235 increased the risk of colorectal cancer in regularly exercising individuals (OR = 1.47, 95% CI = 1.02-2.10) but decreased the risk in non-exercising individuals (OR = 0.76, 95% CI = 0.62-0.94). Furthermore, the G × E between the SNP rs2423279 at 20p12.3 and regular aspirin use was statistically significant (p_case-only = 7.7 × 10^- 3, p_case-control = 1.6 × 10^- 3). The additive effect of the risk allele (T) of rs2423279 on colorectal cancer risk was increased among regular aspirin users (OR = 4.62, 95% CI = 1.97-10.80).

CONCLUSION

Our results suggest that SNP rs4444235 at 14q22.2 and SNP rs2423279 at 20p12.3 may interact with regular exercise and aspirin use in colorectal carcinogenesis.

Single nucleotide polymorphisms associated with susceptibility for development of colorectal cancer: Case-control study in a Basque population

Given the significant population diversity in genetic variation, we aimed to investigate whether single nucleotide polymorphisms (SNPs) previously identified in studies of colorectal cancer (CRC) susceptibility were also relevant to the population of the Basque Country (North of Spain). We genotyped 230 CRC cases and 230 healthy controls for 48 previously reported CRC-susceptibility SNPs. Only the rs6687758 in DUPS10 exhibited a statistically significant association with CRC risk based on the crude analysis. The rs6687758 AG genotype conferred about 2.13-fold increased risk for CRC compared to the AA genotype. Moreover, we found significant associations in cases between smoking status, physical activity, and the rs6687758 SNP. The results of a Genetic Risk Score (GRS) showed that the risk alleles were more frequent in cases than controls and the score was associated with CRC in crude analysis. In conclusion, we have confirmed a CRC susceptibility locus and the existence of associations between modifiable factors and the rs6687758 SNP; moreover, the GRS was associated with CRC. However, further experimental validations are needed to establish the role of this SNP, the function of the gene identified, as well as the contribution of the interaction between environmental factors and this locusto the risk of CRC.

MiR-6803-5p Promotes Cancer Cell Proliferation and Invasion via PTPRO/NF-κB Axis in Colorectal Cancer

Accumulated studies have implicated microRNAs (miRNAs) exert modifying effects on colorectal cancer (CRC). Protein tyrosine phosphatase, receptor type O (PTPRO) has been identified as a tumor suppressor in several kinds of cancer, including CRC. Previously, we have found that exosome-encapsulated miR-6803-5p is increased in CRC. However, the mechanism of miR-6803-5p in CRC is not clear yet. This study is aimed at elucidating the effect of miR-6803-5p in colorectal carcinogenesis. Expression of miR-6803-5p and PTPRO mRNA in peripheral blood mononuclear cells of CRC patients is estimated by real-time PCR. PTPRO protein in CRC cells is detected by western blot. To verify the association of miR-6803-5p with PTPRO, luciferase reporter assay is performed. CCK-8 and EdU assays are conducted to assess cell proliferation. Real-time PCR and ELISA are applied to detect cytokine expression in CRC cells. Cell invasion and migration assays are evaluated by transwell and scratch tests. Immunofluorescence is carried out to determine the activation of NF-κB in HCT116 cells. Negative correlation is demonstrated between miR-6803-5p and PTPRO in CRC. PTPRO is demonstrated to be a direct target of miR-6803-5p. miR-6803-5p can promote cancer cell proliferation and invasion and enhance inflammation through PTPRO/NF-κB axis in CRC, which serves as a useful target for CRC.

Protective Effect of Green Tea Consumption on Colorectal Cancer Varies by Lifestyle Factors

The inconsistent findings regarding green tea intake and colorectal cancer (CRC) risk in several epidemiological studies might result from variations in lifestyle factors. Therefore, we examined whether increased green tea intake was associated with a decreased risk of CRC and how the risk of CRC was altered by the protective effect of green tea consumption and five health-related factors. A case-control study including 2742 participants (922 cases and 1820 controls) was conducted in Korea. Green tea consumption was assessed using a semiquantitative food frequency questionnaire. The risk of CRC was approximately 40% less in the participants in the highest green tea intake tertile than in participants in the lowest green tea intake tertile. Of the five lifestyle factors examined, high body mass index and physical inactivity were independent risk factors for CRC. Regarding the interactions between tea consumption and lifestyle factors, high green tea consumption was associated with a decreased risk of CRC, with or without considering lifestyle factors. However, moderate green tea consumption increased the risk of CRC among ever-smokers, ever-drinkers and the high-inflammatory diet group. Increased consumption of green tea might be helpful to reduce the risk of CRC in those with an unhealthy lifestyle.

Polymorphisms of rs4787050 and rs8045980 are associated with lung cancer risk in northeast Chinese female nonsmokers

Aim: We studied the association between two single-nucleotide polymorphisms (SNPs: rs4787050 and rs8045980) in RBFOX1 and lung cancer risk, and explored the interaction between the two SNPs and exposure to cooking oil fume on lung cancer risk in northeast Chinese female nonsmokers. Methods: Northeast Chinese female nonsmokers were enrolled into the study (people with lung cancer, 647; people without lung cancer, 675). All statistical analyses were performed using SPSS software. Results: The SNPs rs4787050 and rs8045980 showed a significant association with susceptibility to lung cancer. Moreover, cooking oil fume exposure was found to increase the risk of lung cancer. However, no gene-environment interactions were discovered. Conclusion: The present study revealed that rs4787050 and rs8045980 in RBFOX1 may be meaningful as a novel biomarker for lung cancer susceptibility.

Prevalence and risk factors of colorectal cancer in Asia

Globally, colorectal cancer (CRC) is a substantial public health burden, and it is increasingly affecting populations in Asian countries. The overall prevalence of CRC is reported to be low in Asia when compared with that in Western nations, yet it had the highest number of prevalent cases. This review described the prevalence of CRC in Asia according to the International Agency for Research on Cancer from World Health Organization (WHO) database and summarized its major risk factors. Non-modifiable factors include genetic factors, ethnicity, age, gender, family history and body height; smoking, alcohol drinking, weight, Westernized diet, physical inactivity, chronic diseases and microbiota were involved in environmental factors. These risk factors were separately discussed in this review according to published literature from Asian countries. CRC screening has been playing an important role in reducing its disease burden. Some recommendations on its screening practices have been formulated in guidelines for Asia Pacific countries.