Association of Dietary Patterns With Risk of Colorectal Cancer Subtypes Classified by Fusobacterium nucleatum in Tumor Tissue

Difference in Gastrointestinal Cancer Risk and Mortality by Dietary Pattern Analysis: A Systematic Review and Meta-Analysis

CONTEXT

Several studies have demonstrated that dietary patterns identified by a posteriori and hybrid methods are associated with gastrointestinal (GI) cancer risk and mortality. These studies applied different methods for analyzing dietary data and reported inconsistent findings.

OBJECTIVE

This systematic review and meta-analysis were aimed to determine the association between dietary patterns, derived using principal component analysis (PCA) and reduced rank regression (RRR), and GI cancer risk and GI cancer-caused mortality.

DATA SOURCE

Articles published up to June 2023 in English were eligible for inclusion. The Medline, SCOPUS, Cochrane Library, CINHAL, PsycINFO, ProQuest, and Web of Sciences databases were used to identify prospective studies. The Preferred Reporting Item for Systematic Review and Meta-analysis Protocol 2020 was used to report results.

DATA EXTRACTION

A total of 28 studies were eligible for inclusion. Varied approaches to deriving dietary patterns were used, including PCA (n = 22), RRR (n = 2), combined PCA and RRR (n = 1), cluster analysis (CA; n = 2) and combined PCA and CA (n = 1).

DATA ANALYSIS

Two dietary patterns, "healthy" and "unhealthy," were derived using PCA and RRR. The healthy dietary pattern was characterized by a higher intake of fruits, whole grains, legumes, vegetables, milk, and other dairy products, whereas the unhealthy dietary pattern was characterized by a higher intake of red and processed meat, alcohol, and both refined and sugar-sweetened beverages. The findings indicated that the PCA-derived healthy dietary pattern was associated with an 8% reduced risk (relative risk [RR], 0.92; 95% CI, 0.87-0.98), and the unhealthy dietary pattern was associated with a 14% increased risk (RR, 1.14; 95% CI, 1.07-1.22) of GI cancers. Similarly, the RRR-derived healthy dietary pattern (RR, 0.83; 95% CI, 0.61-1.12) may be associated with reduced risk of GI cancers. In contrast, the RRR-derived unhealthy dietary pattern (RR, 0.93; 95% CI, 0.57-1.52) had no association with a reduced risk of GI cancers. Similarly, evidence suggested that PCA-derived healthy dietary patterns may reduce the risk of death from GI cancers, whereas PCA-derived unhealthy dietary patterns may increase the risk.

CONCLUSION

Findings from prospective studies on the association of PCA-derived dietary patterns and the risk of GI cancers support the evidence of healthy and unhealthy dietary patterns as either protective or risk-increasing factors for GI cancers and for survivorship, respectively. The findings also suggest that the RRR-derived healthy dietary pattern reduces the risk of GI cancers (albeit with low precision), but no association was found for the RRR-derived unhealthy dietary pattern. Prospective studies are required to further clarify disparities in the association between PCA- and RRR-derived dietary patterns and the risk of GI cancers. Systematic review registration: PROSPERO registration no. CRD42022321644.

The role of Fusobacterium nucleatum in cancer and its implications for clinical applications

Fusobacterium nucleatum, a gram-negative anaerobic bacterium abundantly found in the human oral cavity, is widely recognized as a key pathobiont responsible for the initiation and progression of periodontal diseases due to its remarkable aggregative capabilities. Numerous clinical studies have linked F. nucleatum with unfavorable prognostic outcomes in various malignancies. In further research, scholars have partially elucidated the mechanisms underlying F. nucleatum's impact on various types of cancer, thus gaining a certain comprehension of the role played by F. nucleatum in cancer. In this comprehensive review, we present an in-depth synthesis of the interplay between F. nucleatum and different cancers, focusing on aspects such as tumor initiation, metastasis, chemoresistance, and modulation of the tumor immune microenvironment and immunotherapy. The implications for cancer diagnosis and treatment are also summarized. The objective of this review is to enhance our comprehension of the intricate relationship between F. nucleatum and oncogenic pathogenesis, while emphasizing potential therapeutic strategies.

Interactions between diet and gut microbiota in cancer

Dietary patterns and specific dietary components, in concert with the gut microbiota, can jointly shape susceptibility, resistance and therapeutic response to cancer. Which diet-microbial interactions contribute to or mitigate carcinogenesis and how they work are important questions in this growing field. Here we interpret studies of diet-microbial interactions to assess dietary determinants of intestinal colonization by opportunistic and oncogenic bacteria. We explore how diet-induced expansion of specific gut bacteria might drive colonic epithelial tumorigenesis or create immuno-permissive tumour milieus and introduce recent findings that provide insight into these processes. Additionally, we describe available preclinical models that are widely used to study diet, microbiome and cancer interactions. Given the rising clinical interest in dietary modulations in cancer treatment, we highlight promising clinical trials that describe the effects of different dietary alterations on the microbiome and cancer outcomes.

Host-diet-microbiota interplay in intestinal nutrition and health

The intestine is populated by a complex and dynamic assortment of microbes, collectively called gut microbiota, that interact with the host and contribute to its metabolism and physiology. Diet is considered a key regulator of intestinal microbiota, as ingested nutrients interact with and shape the resident microbiota composition. Furthermore, recent studies underscore the interplay of dietary and microbiota-derived nutrients, which directly impinge on intestinal stem cells regulating their turnover to ensure a healthy gut barrier. Although advanced sequencing methodologies have allowed the characterization of the human gut microbiome, mechanistic studies assessing diet-microbiota-host interactions depend on the use of genetically tractable models, such as Drosophila melanogaster. In this review, we first discuss the similarities between the human and fly intestines and then we focus on the effects of diet and microbiota on nutrient-sensing signaling cascades controlling intestinal stem cell self-renewal and differentiation, as well as disease. Finally, we underline the use of the Drosophila model in assessing the role of microbiota in gut-related pathologies and in understanding the mechanisms that mediate different whole-body manifestations of gut dysfunction.

Guideline for designing microbiome studies in neoplastic diseases

Oncobiosis has emerged as a key contributor to the development, and modulator of the treatment efficacy of cancer. Hereby, we review the modalities through which the oncobiome can support the progression of tumors, and the emerging therapeutic opportunities they present. The review highlights the inherent challenges and limitations faced in sampling and accurately characterizing oncobiome. Additionally, the review underscores the critical need for the standardization of microbial analysis techniques and the consistent reporting of microbiome data. We provide a suggested metadata set that should accompany microbiome datasets from oncological settings so that studies remain comparable and decipherable.

Utilization of the microbiome in personalized medicine

Inter-individual human variability, driven by various genetic and environmental factors, complicates the ability to develop effective population-based early disease detection, treatment and prognostic assessment. The microbiome, consisting of diverse microorganism communities including viruses, bacteria, fungi and eukaryotes colonizing human body surfaces, has recently been identified as a contributor to inter-individual variation, through its person-specific signatures. As such, the microbiome may modulate disease manifestations, even among individuals with similar genetic disease susceptibility risks. Information stored within microbiomes may therefore enable early detection and prognostic assessment of disease in at-risk populations, whereas microbiome modulation may constitute an effective and safe treatment tailored to the individual. In this Review, we explore recent advances in the application of microbiome data in precision medicine across a growing number of human diseases. We also discuss the challenges, limitations and prospects of analysing microbiome data for personalized patient care.

Unraveling the complexities of early-onset colorectal cancer: a perspective on dietary and microbial influences

While advances in screening have resulted in declining rates of colorectal cancer (CRC) among adults ≥50 years of age since the mid-2000s, the incidence of early-onset CRC (EOCRC) has steadily increased over the last decade. This increase is not fully accounted for by hereditary factors, and the hypothesis that a sedentary lifestyle and obesity are the primary culprits is not fully supported by recent reports indicating that many affected individuals lead active lifestyles, maintain normal weight, and are otherwise healthy. Attention has shifted toward dietary patterns, notably the consumption of processed and ultra-processed foods found in Western diets, which are suspected of disrupting the gut microbiome balance that potentially leads to EOCRC. The impact of antibiotic use on the gut microbiome is also posited as a contributing factor, given its rising prevalence in medical and agricultural practices. We propose that a paradigm shift is necessary for EOCRC research, moving beyond metabolic factors to a broader exploration of dietary and microbial influences. Future research must prioritize understanding the relationship between dietary habits, particularly processed food intake, antibiotic exposure, and gut microbiome dynamics, to unravel the complex etiology of EOCRC. This will be crucial in developing comprehensive preventive strategies to address the increasing incidence of this malignancy in younger populations.

Analytical challenges in omics research on asthma and allergy: A National Institute of Allergy and Infectious Diseases workshop

Studies of asthma and allergy are generating increasing volumes of omics data for analysis and interpretation. The National Institute of Allergy and Infectious Diseases (NIAID) assembled a workshop comprising investigators studying asthma and allergic diseases using omics approaches, omics investigators from outside the field, and NIAID medical and scientific officers to discuss the following areas in asthma and allergy research: genomics, epigenomics, transcriptomics, microbiomics, metabolomics, proteomics, lipidomics, integrative omics, systems biology, and causal inference. Current states of the art, present challenges, novel and emerging strategies, and priorities for progress were presented and discussed for each area. This workshop report summarizes the major points and conclusions from this NIAID workshop. As a group, the investigators underscored the imperatives for rigorous analytic frameworks, integration of different omics data types, cross-disciplinary interaction, strategies for overcoming current limitations, and the overarching goal to improve scientific understanding and care of asthma and allergic diseases.

Effects of dietary intervention on human diseases: molecular mechanisms and therapeutic potential

Diet, serving as a vital source of nutrients, exerts a profound influence on human health and disease progression. Recently, dietary interventions have emerged as promising adjunctive treatment strategies not only for cancer but also for neurodegenerative diseases, autoimmune diseases, cardiovascular diseases, and metabolic disorders. These interventions have demonstrated substantial potential in modulating metabolism, disease trajectory, and therapeutic responses. Metabolic reprogramming is a hallmark of malignant progression, and a deeper understanding of this phenomenon in tumors and its effects on immune regulation is a significant challenge that impedes cancer eradication. Dietary intake, as a key environmental factor, can influence tumor metabolism. Emerging evidence indicates that dietary interventions might affect the nutrient availability in tumors, thereby increasing the efficacy of cancer treatments. However, the intricate interplay between dietary interventions and the pathogenesis of cancer and other diseases is complex. Despite encouraging results, the mechanisms underlying diet-based therapeutic strategies remain largely unexplored, often resulting in underutilization in disease management. In this review, we aim to illuminate the potential effects of various dietary interventions, including calorie restriction, fasting-mimicking diet, ketogenic diet, protein restriction diet, high-salt diet, high-fat diet, and high-fiber diet, on cancer and the aforementioned diseases. We explore the multifaceted impacts of these dietary interventions, encompassing their immunomodulatory effects, other biological impacts, and underlying molecular mechanisms. This review offers valuable insights into the potential application of these dietary interventions as adjunctive therapies in disease management.

Broadening oncological boundaries: the intratumoral microbiota

The microbiota of solid tumors was identified >100 years ago; however, heterogeneous composition and diversity have been revealed only recently. Growing evidence has suggested that several functional mechanisms of the intratumoral microbiota affect tumorigenesis and progression, suggesting that the intratumoral microbiota is a promising biomarker for multiple cancers. The low biomass of the intratumoral microbiota poses a major challenge to related research, thus necessitating the use of a multiple-modality integrated framework to resolve this dilemma. Advanced techniques such as single-cell sequencing provide significant clues, and the gradual optimization of functional experiments and culture-based methods enables deeper investigation of the underlying mechanisms involved. In this review, we outline the current state of research on the intratumoral microbiota and describe the challenges and comprehensive strategies for future research.

The effect of selenium supplementation on disease activity and immune-inflammatory biomarkers in patients with mild-to-moderate ulcerative colitis: a randomized, double-blind, placebo-controlled clinical trial

PURPOSE

Selenium (Se) supplementation may help reduce inflammation and disease activity in ulcerative colitis (UC) patients. We investigated the therapeutic effects of Se administration in cases with mild-to-moderate active UC.

METHODS

A multicenter, double-blind, randomized clinical trial (RCT) was conducted on 100 cases with active mild-to-moderate UC. The patients were randomly allocated to be given an oral selenomethionine capsule (200 mcg/day, n = 50) or a placebo capsule (n = 50) for 10 weeks. The primary outcome was defined as disease activity via the Simple Clinical Colitis Activity Index (SCCAI), and secondary outcomes were measured at the end of the study.

RESULTS

After 10 weeks, the SCCAI score's mean was reduced in the Se group (P < 0.001). At the end of the intervention, clinical improvement (decline of 3 ≥ score from baseline score) was observed in 19 patients (38%) of the Se group and 3 patients (6%) of the placebo group. The patients with clinical remission (defined as SCCAI ≤ 2) were assigned in the Se group (P = 0.014). The Se group's quality of life and Se serum levels were enhanced at the end of the study (P < 0/001). In the Se group, the mean concentration of interleukin-17 decreased (P < 0/001). However, the levels of interleukin-10 showed no considerable change between the two groups in the 10th week (P = 0.23).

CONCLUSION

Se supplementation as add-on therapy with medical management induced remission and improved the quality of life in patients with active mild-to-moderate UC.

TRIAL REGISTRATION NUMBER AND DATE OF REGISTRATION

IRCT20091114002709N51; 2020-04-13.

The microbiome and rise of early-onset cancers: knowledge gaps and research opportunities

Accumulating evidence indicates an alarming increase in the incidence of early-onset cancers, which are diagnosed among adults under 50 years of age, in the colorectum, esophagus, extrahepatic bile duct, gallbladder, liver, stomach, pancreas, as well as the bone marrow (multiple myeloma), breast, head and neck, kidney, prostate, thyroid, and uterine corpus (endometrium). While the early-onset cancer studies have encompassed research on the wide variety of organs, this article focuses on research on digestive system cancers. While a minority of early-onset cancers in the digestive system are associated with cancer-predisposing high penetrance germline genetic variants, the majority of those cancers are sporadic and multifactorial. Although potential etiological roles of diets, lifestyle, environment, and the microbiome from early life to adulthood (i.e. in one's life course) have been hypothesized, exact contribution of each of these factors remains uncertain. Diets, lifestyle patterns, and environmental exposures have been shown to alter the oral and intestinal microbiome. To address the rising trend of early-onset cancers, transdisciplinary research approaches including lifecourse epidemiology and molecular pathological epidemiology frameworks, nutritional and environmental sciences, multi-omics technologies, etc. are needed. We review current evidence and discuss emerging research opportunities, which can improve our understanding of their etiologies and help us design better strategies for prevention and treatment to reduce the cancer burden in populations.

Bacteria in cancer initiation, promotion and progression

Cancer cells originate from a series of acquired genetic mutations that can drive their uncontrolled cell proliferation and immune evasion. Environmental factors, including the microorganisms that colonize the human body, can shift the metabolism, growth pattern and function of neoplastic cells and shape the tumour microenvironment. Dysbiosis of the gut microbiome is now recognized as a hallmark of cancer by the scientific community. However, only a few microorganisms have been identified that directly initiate tumorigenesis or skew the immune system to generate a tumour-permissive milieu. Over the past two decades, research on the human microbiome and its functionalities within and across individuals has revealed microbiota-focused strategies for health and disease. Here, we review the evolving understanding of the mechanisms by which the microbiota acts in cancer initiation, promotion and progression. We explore the roles of bacteria in gastrointestinal tract malignancies and cancers of the lung, breast and prostate. Finally, we discuss the promises and limitations of targeting or harnessing bacteria in personalized cancer prevention, diagnostics and treatment.

The Pathogenicity of Fusobacterium nucleatum Modulated by Dietary Fibers-A Possible Missing Link between the Dietary Composition and the Risk of Colorectal Cancer

The dietary composition has been approved to be strongly associated with the risk of colorectal cancer (CRC), one of the most serious malignancies worldwide, through regulating the gut microbiota structure, thereby influencing the homeostasis of colonic epithelial cells by producing carcinogens, i.e., ammonia or antitumor metabolites, like butyrate. Though butyrate-producing Fusobacterium nucleatum has been considered a potential tumor driver associated with chemotherapy resistance and poor prognosis in CRC, it was more frequently identified in the gut microbiota of healthy individuals rather than CRC tumor tissues. First, within the concentration range tested, the fermentation broth of F. nucleatum exhibited no significant effects on Caco-2 and NCM460 cells viability except for a notable up-regulation of the expression of TLR4 (30.70%, p < 0.0001) and Myc (47.67%, p = 0.021) and genes encoding proinflammatory cytokines including IL1B (197.57%, p < 0.0001), IL6 (1704.51%, p < 0.0001), and IL8 (897.05%, p < 0.0001) in Caco-2 cells exclusively. Although no marked effects of polydextrose or fibersol-2 on the growth of F. nucleatum, Caco-2 and NCM460 cells were observed, once culture media supplemented with polydextrose or fibersol-2, the corresponding fermentation broths of F. nucleatum significantly inhibited the growth of Caco-2 cells up to 48.90% (p = 0.0003, 72 h, 10%) and 52.96% (p = 0.0002, 72 h, 10%), respectively in a dose-dependent manner. These two kinds of fibers considerably promoted butyrate production of F. nucleatum up to 205.67% (p < 0.0001, 6% polydextrose at 24 h) and 153.46% (p = 0.0002, 6% fibersol-2 at 12 h), which explained why and how the fermentation broths of F. nucleatum cultured with fibers suppressing the growth of Caco-2 cells. Above findings indicated that dietary fiber determined F. nucleatum to be a carcinogenic or antitumor bacterium, and F. nucleatum played an important role in the association between the dietary composition, primarily the content of dietary fibers, and the risk of CRC.

Inverse relationship between Fusobacterium nucleatum amount and tumor CD274 (PD-L1) expression in colorectal carcinoma

Objectives

The CD274 (programmed cell death 1 ligand 1, PD-L1)/PDCD1 (programmed cell death 1, PD-1) immune checkpoint axis is known to regulate the antitumor immune response. Evidence also supports an immunosuppressive effect of Fusobacterium nucleatum. We hypothesised that tumor CD274 overexpression might be inversely associated with abundance of F. nucleatum in colorectal carcinoma.

Methods

We assessed tumor CD274 expression by immunohistochemistry and F. nucleatum DNA within tumor tissue by quantitative PCR in 812 cases among 4465 incident rectal and colon cancer cases that had occurred in two prospective cohort studies. Multivariable logistic regression analyses with inverse probability weighting were used to adjust for selection bias because of tissue data availability and potential confounders including microsatellite instability status, CpG island methylator phenotype, LINE-1 methylation level and KRAS, BRAF and PIK3CA mutations.

Results

Fusobacterium nucleatum DNA was detected in tumor tissue in 109 (13%) cases. Tumor CD274 expression level was inversely associated with the amount of F. nucleatum in colorectal cancer tissue (P = 0.0077). For one category-unit increase in three ordinal F. nucleatum categories (negative vs. low vs. high), multivariable-adjusted odds ratios (with 95% confidence interval) of the low, intermediate and high CD274 categories (vs. negative) were 0.78 (0.41-1.51), 0.64 (0.32-1.28) and 0.50 (0.25-0.99), respectively (P trend = 0.032).

Conclusions

Tumor CD274 expression level was inversely associated with the amount of F. nucleatum in colorectal cancer tissue, suggesting that different immunosuppressive mechanisms (i.e. PDCD1 immune checkpoint activation and tumor F. nucleatum enrichment) tend to be used by different tumor subgroups.

An Overview of Selected Bacterial Infections in Cancer, Their Virulence Factors, and Some Aspects of Infection Management

In cancer development and its clinical course, bacteria can be involved in etiology and secondary infection. Regarding etiology, various epidemiological studies have revealed that Helicobacter pylori can directly impact gastric carcinogenesis. The Helicobacter pylori-associated virulence factor cytotoxin-associated gene A perhaps plays an important role through different mechanisms such as aberrant DNA methylation, activation of nuclear factor kappa B, and modulation of the Wnt/β-catenin signaling pathway. Many other bacteria, including Salmonella and Pseudomonas, can also affect Wnt/β-catenin signaling. Although Helicobacter pylori is involved in both gastric adenocarcinoma and mucosa-associated lymphoid tissue lymphoma, its role in the latter disease is more complicated. Among other bacterial species, Chlamydia is linked with a diverse range of diseases including cancers of different sites. The cellular organizations of Chlamydia are highly complex. Interestingly, Escherichia coli is believed to be associated with colon cancer development. Microorganisms such as Escherichia coli and Pseudomonas aeruginosa are frequently isolated from secondary infections in cancer patients. In these patients, the common sites of infection are the respiratory, gastrointestinal, and urinary tracts. There is an alarming rise in infections with multidrug-resistant bacteria and the scarcity of suitable antimicrobial agents adversely influences prognosis. Therefore, effective implementation of antimicrobial stewardship strategies is important in cancer patients.

Gut Microbiota Enterotypes Mediate the Effects of Dietary Patterns on Colorectal Neoplasm Risk in a Chinese Population

Colorectal cancer (CRC) risk is influenced by dietary patterns and gut microbiota enterotypes. However, the interaction between these factors remains unclear. This study examines this relationship, hypothesizing that different diets may affect colorectal tumor risk in individuals with varied gut microbiota enterotypes. We conducted a case-control study involving 410 Han Chinese individuals, using exploratory structural equation modeling to identify two dietary patterns, and a Dirichlet multinomial mixture model to classify 250 colorectal neoplasm cases into three gut microbiota enterotypes. We assessed the association between dietary patterns and the risk of each tumor subtype using logistic regression analysis. We found that a healthy diet, rich in vegetables, fruits, milk, and yogurt, lowers CRC risk, particularly in individuals with type I (dominated by Bacteroides and Lachnoclostridium) and type II (dominated by Bacteroides and Faecalibacterium) gut microbiota enterotypes, with adjusted odds ratios (ORs) of 0.66 (95% confidence interval [CI] = 0.48-0.89) and 0.42 (95% CI = 0.29-0.62), respectively. Fruit consumption was the main contributor to this protective effect. No association was found between a healthy dietary pattern and colorectal adenoma risk or between a high-fat diet and colorectal neoplasm risk. Different CRC subtypes associated with gut microbiota enterotypes displayed unique microbial compositions and functions. Our study suggests that specific gut microbiota enterotypes can modulate the effects of diet on CRC risk, offering new perspectives on the relationship between diet, gut microbiota, and colorectal neoplasm risk.

Role of gut microbiota and bacterial metabolites in mucins of colorectal cancer

Colorectal cancer (CRC) is a major health burden, accounting for approximately 10% of all new cancer cases worldwide. Accumulating evidence suggests that the crosstalk between the host mucins and gut microbiota is associated with the occurrence and development of CRC. Mucins secreted by goblet cells not only protect the intestinal epithelium from microorganisms and invading pathogens but also provide a habitat for commensal bacteria. Conversely, gut dysbiosis results in the dysfunction of mucins, allowing other commensals and their metabolites to pass through the intestinal epithelium, potentially triggering host responses and the subsequent progression of CRC. In this review, we summarize how gut microbiota and bacterial metabolites regulate the function and expression of mucin in CRC and novel treatment strategies for CRC.

Principles of Molecular Utility for CMS Classification in Colorectal Cancer Management

Colorectal cancer (CRC) is the second cause of cancer-related deaths in both sexes globally and presents different clinical outcomes that are described by a range of genomic and epigenomic alterations. Despite the advancements in CRC screening plans and treatment strategies, the prognosis of CRC is dismal. In the last two decades, molecular biomarkers predictive of prognosis have been identified in CRC, although biomarkers predictive of treatment response are only available for specific biological drugs used in stage IV CRC. Translational clinical trials mainly based on "omic" strategies allowed a better understanding of the biological heterogeneity of CRCs. These studies were able to classify CRCs into subtypes mainly related to prognosis, recurrence risk, and, to some extent, also to treatment response. Accordingly, the comprehensive molecular characterizations of CRCs, including The Cancer Genome Atlas (TCGA) and consensus molecular subtype (CMS) classifications, were presented to improve the comprehension of the genomic and epigenomic landscapes of CRCs for a better patient management. The CMS classification obtained by the CRC subtyping consortium categorizes CRC into four consensus molecular subtypes (CMS1-4) characterized by different prognoses. In this review, we discussed the CMS classification in different settings with a focus on its relationships with precursor lesions, tumor immunophenotype, and gut microbiota, as well as on its role in predicting prognosis and/or response to pharmacological treatments, as a crucial step towards precision medicine.

Mediation effect of intestinal microbiota on the relationship between fiber intake and colorectal cancer

Higher fiber intake has been associated with a lower risk of colorectal cancer (CRC) and has been shown to protect against CRC based on probable evidence. Recent studies revealed a possible mechanism whereby the interaction between intestinal microbiota and fiber intake mediates CRC risk. However, the specific intestinal bacteria and the amount of these bacteria involved in this mechanism are not fully known. Therefore, this single-center study aimed to determine whether specific intestinal bacteria mediated the relationship between fiber intake and CRC risk. We enrolled patients who received colonoscopy at National Cancer Center Hospital. This cross-sectional study included 180 patients with clinically diagnosed CRC and 242 controls. We conducted a causal mediation analysis to assess the natural indirect effect and natural direct effect of specific intestinal bacteria on association between fiber intake and CRC risk. The median age was 64 (interquartile range, 54-70) years, and 58% of the participants were males. We used metagenomics for profiling gut microbiomes. The relative abundance of each species in each sample was calculated. Among the candidate, Fusobacterium nucleatum and Gemella morbillorum had a significant natural indirect effect based on their highest fiber intake compared to the lowest fiber intake, with a risk difference (95% confidence interval, proportion of mediation effect) of -0.06 [-0.09 to -0.03, 23%] and -0.03 [-0.06 to -0.01, 10.5%], respectively. Other bacteria did not display natural indirect effects. In conclusion, Fusobacterium nucleatum and Gemella morbillorum were found to mediate the relationship between fiber intake and CRC risk.

Western diet influences on microbiome and carcinogenesis

The intestinal microbiota composition and associated bioactivities are sensitive to various modifier cues such as stress, inflammation, age, life-style and nutrition, which in turn are associated with susceptibility to developing cancer. Among these modifiers, diet has been shown to influence both microbiota composition as well as being an important source of microbial-derived compounds impacting the immunological, neurological and hormonal systems. Thus, it is necessary to take a holistic view when considering effect of diet on health and diseases. In this review, we focus on the interplay between western diet, the microbiota and cancer development by dissecting key components of the diet and leveraging data from human interventions and pre-clinical studies to better understand this relationship. We highlight key progress as well as stressing limitations in this field of research.

Histopathology images predict multi-omics aberrations and prognoses in colorectal cancer patients

Histopathologic assessment is indispensable for diagnosing colorectal cancer (CRC). However, manual evaluation of the diseased tissues under the microscope cannot reliably inform patient prognosis or genomic variations crucial for treatment selections. To address these challenges, we develop the Multi-omics Multi-cohort Assessment (MOMA) platform, an explainable machine learning approach, to systematically identify and interpret the relationship between patients' histologic patterns, multi-omics, and clinical profiles in three large patient cohorts (n = 1888). MOMA successfully predicts the overall survival, disease-free survival (log-rank test P-value<0.05), and copy number alterations of CRC patients. In addition, our approaches identify interpretable pathology patterns predictive of gene expression profiles, microsatellite instability status, and clinically actionable genetic alterations. We show that MOMA models are generalizable to multiple patient populations with different demographic compositions and pathology images collected from distinctive digitization methods. Our machine learning approaches provide clinically actionable predictions that could inform treatments for colorectal cancer patients.

Intratumour Fusobacterium nucleatum and immune response to oesophageal cancer

BACKGROUND

Experimental evidence suggests a role of intratumour Fusobacterium nucleatum in the aggressive behaviour of gastrointestinal cancer through downregulating anti-tumour immunity. We investigated the relationship between intratumour F. nucleatum and immune response to oesophageal cancer.

METHODS

Utilising an unbiased database of 300 resected oesophageal cancers, we measured F. nucleatum DNA in tumour tissue using a quantitative polymerase chain reaction assay, and evaluated the relationship between the abundance of F. nucleatum and the densities of T cells (CD8 + , FOXP3 + and PDCD1 + ), as well as lymphocytic reaction patterns (follicle lymphocytic reaction, peritumoural lymphocytic reaction, stromal lymphocytic reaction and tumour-infiltrating lymphocytes) in oesophageal carcinoma tissue.

RESULTS

F. nucleatum was significantly and inversely associated only with the peritumoural lymphocytic reaction (P = 0.0002). Compared with the F. nucleatum-absent group, the F. nucleatum-high group showed a much lower level of the peritumoural lymphocytic reaction (univariable odds ratio, 0.33; 95% confidence interval, 0.16-0.65; P = 0.0004). A multivariable model yielded a similar finding (multivariable odds ratio, 0.34; 95% confidence interval 0.16-0.69; P = 0.002).

CONCLUSIONS

Intratumour F. nucleatum is associated with a diminished peritumoural lymphocytic reaction, providing a platform for further investigations on the potential interactive roles between intratumour F. nucleatum and host immunity.

Biotherapy Using Probiotics as Therapeutic Agents to Restore the Gut Microbiota to Relieve Gastrointestinal Tract Inflammation, IBD, IBS and Prevent Induction of Cancer

The gut microbiota is composed of several microbial strains with diverse and variable compositions in both healthy and sick people. An undisturbed gut microbiota needs to be sustained in order to perform all physiological, metabolic, and immune functions in a normal way to prevent the development of diseases. This article has reviewed the published information on the issue of disruption of the balance of the gut microbiota. This disruption could be for many reasons, such as microbial infection in the gastrointestinal tract, food poisoning, diarrhoea, chemotherapy, malnutrition, lifestyle, and ageing. If this disruption is not restored to normal, it might cause dysbiosis. Eventually, a gut microbiota interrupted by dysbiosis might initiate several health issues, such as inflammation of the gastrointestinal tract, the induction of cancer, and the progression of a variety of diseases such as irritable bowel syndrome and inflammatory bowel disease. This review concluded that biotherapy is a natural way of using probiotic products, whether in form of food, beverages, or supplements, to restore the gut microbiota disrupted by dysbiosis. Metabolites secreted by the ingested probiotics help to relieve gastrointestinal tract inflammation and can avoid the induction of cancer.

Global research on the crosstalk between intestinal microbiome and colorectal cancer: A visualization analysis

Background

Increasing evidence has shown that the intestinal microbiome (IM) is highly linked to colorectal cancer (CRC). To investigate scientific output, identify highly cited papers, and explore research hotspots and trends in the field of IM/CRC, we conducted a bibliometric and visualized analysis.

Methods

A bibliographic search regarding IM/CRC research (2012-2021) was implemented on October 17, 2022. The terms attached to IM and CRC were searched for in the titles (TI), abstracts (AB), and author keywords (AK). The main information was extracted from the Web of Science Core Collection (WoSCC). Biblioshiny from R packages and VOSviewer were used for data visualization.

Results

A total of 1725 papers related to IM/CRC were retrieved. Publications on IM/CRC have grown rapidly from 2012 to 2021. China and the United States were in the leading position for publications in this field and made the most significant contributions to IM/CRC research. Shanghai Jiao Tong University and Harvard University were the most productive institutions. The high-yield authors were Yu Jun and Fang Jing Yuan. The International Journal of Molecular Sciences published the most papers, whereas Gut had the most citations. Historical citation analysis showed the evolution of IM/CRC research. Current status and hotspots were highlighted using keyword cluster analysis. The hot topics include the effect of IM on tumorigenesis, the effect of IM on CRC treatment, the role of IM in CRC screening, the mechanisms of IM involvement in CRC, and IM modulation for CRC management. Some topics, such as chemotherapy, immunotherapy, Fusobacterium nucleatum and short-chain fatty acids could be the focus of IM/CRC research in the coming years.

Conclusion

This research evaluated the global scientific output of IM/CRC research and its quantitative features, identified some significant papers, and gathered information on the status and trends of IM/CRC research, which may shape future paths for academics and practitioners.

Microbiome and Diet in Colon Cancer Development and Treatment

ABSTRACT

Diet plays critical roles in defining our immune responses, microbiome, and progression of human diseases. With recent progress in sequencing and bioinformatic techniques, increasing evidence indicates the importance of diet-microbial interactions in cancer development and therapeutic outcome. Here, we focus on the epidemiological studies on diet-bacterial interactions in the colon cancer. We also review the progress of mechanistic studies using the experimental models. Finally, we discuss the limits and future directions in the research of microbiome and diet in cancer development and therapeutic outcome. Now, it is clear that microbes can influence the efficacy of cancer therapies. These research results open new possibilities for the diagnosis, prevention, and treatment of cancer. However, there are still big gaps to apply these new findings to the clinical practice.

Possible role of nutrition in the prevention of inflammatory bowel disease-related colorectal cancer: A focus on human studies

Patients with inflammatory bowel disease (IBD) are at substantially high risk for colorectal cancer (CRC). IBD-associated CRC accounts for roughly 10% to 15% of the annual mortality in patients with IBD. IBD-related CRC also affects younger patients compared with sporadic CRC, with a 5-y survival rate of 50%. Regardless of medical therapies, the persistent inflammatory state characterizing IBD raises the risk for precancerous changes and CRC, with additional input from several elements, including genetic and environmental risk factors, IBD-associated comorbidities, intestinal barrier dysfunction, and gut microbiota modifications. It is well known that nutritional habits and dietary bioactive compounds can influence IBD-associated inflammation, microbiome abundance and composition, oxidative stress balance, and gut permeability. Additionally, in recent years, results from broad epidemiologic and experimental studies have associated certain foods or nutritional patterns with the risk for colorectal neoplasia. The present study aimed to review the possible role of nutrition in preventing IBD-related CRC, focusing specifically on human studies. It emerges that nutritional interventions based on healthy, nutrient-dense dietary patterns characterized by a high intake of fiber, vegetables, fruit, ω-3 polyunsaturated fatty acids, and a low amount of animal proteins, processed foods, and alcohol, combined with probiotic supplementation have the potential of reducing IBD-activity and preventing the risk of IBD-related CRC through different mechanisms, suggesting that targeted nutritional interventions may represent a novel promising approach for the prevention and management of IBD-associated CRC.

The Pleiotropic Effects of Gut Microbiota in Colorectal Cancer Progression: How to Turn Foes into Friends

Colorectal Cancer (CRC) is one of most frequent malignant cancers, showing high lethality worldwide [...].

Microbiome epidemiology and association studies in human health

Studies of the human microbiome share both technical and conceptual similarities with genome-wide association studies and genetic epidemiology. However, the microbiome has many features that differ from genomes, such as its temporal and spatial variability, highly distinct genetic architecture and person-to-person variation. Moreover, there are various potential mechanisms by which distinct aspects of the human microbiome can relate to health outcomes. Recent advances, including next-generation sequencing and the proliferation of multi-omic data types, have enabled the exploration of the mechanisms that connect microbial communities to human health. Here, we review the ways in which features of the microbiome at various body sites can influence health outcomes, and we describe emerging opportunities and future directions for advanced microbiome epidemiology.

Association Between Diet and Fusobacterium nucleatum in the Feces of Healthy Adults: A Hospital-based Cross-sectional Study

Fusobacterium nucleatum is involved in the development and progression of colorectal cancer. Although the gut microbiota is influenced by diet, studies on the association between diet and F. nucleatum are limited. We aimed to evaluate the association between various dietary factors and fecal F. nucleatum in healthy adults without a history of colorectal cancer or precancerous lesions. This was a cross-sectional study. Subjects who underwent total colonoscopy at the National Cancer Center Hospital (Tokyo, Japan) were included. Healthy subjects (n = 212) were divided into two groups according to the presence or absence of F. nucleatum in their feces which was calculated from data of whole-genome shotgun sequencing, with the group with F. nucleatum serving as cases and the group without F. nucleatum serving as controls. Multivariable logistic regression analysis adjusted potential confounders was conducted to estimate the associations between dietary intake and nutrients estimated by a validated food frequency questionnaire and the presence of F. nucleatum in the feces. There was a significant inverse association between dairy products and the presence of fecal F. nucleatum [high vs. low; OR, 0.41; 95% confidence interval, 0.17-0.95; Ptrend, 0.039]. These results may have important implications for colorectal cancer prevention through nutritional intervention.

PREVENTION RELEVANCE

F. nucleatum is well known as a colorectal cancer-associated bacterium. Dietary habits alter the composition and function of the intestinal microbiota. A high intake of dairy products in healthy adults may reduce F. nucleatum and prevent colorectal cancer.

High-intensity mechanical bowel preparation before curative colorectal surgery is associated with poor long-term prognosis

PURPOSE

Mechanical bowel preparation (MBP) has been widely used to reduce intestinal feces and bacteria and is considered necessary to prevent surgical infections. However, it is still controversial which intensity level of MBP is the most beneficial for patients before colorectal surgery. Our study aimed to determine the impact of different intensity levels of MBP on the progression-free survival (PFS) and overall survival (OS) for colorectal cancer (CRC) patients.

METHODS

We evaluated 694 patients pathologically diagnosed with CRC and underwent MBP before surgery at 4 general hospitals from January 2011 to December 2015. The survival status of patients, the disease progression, and the time of death or progression were obtained through telephone follow-up at the deadline October 10, 2018. Hazard ratios were estimated by Cox proportional hazard models. Survival was assessed using the Kaplan-Meier method followed by the log-rank test.

RESULTS

Of 694 patients included, 462 received low-intensity MBP and 232 received high-intensity MBP. A significantly higher PFS in low-intensity MBP was observed (p = 0.009). PFS at 2000 days was 69.331% in the low-intensity arm and 58.717% in the high-intensity arm. Patients who underwent low-intensity MBP also showed higher OS (p = 0.009). Nine patients in the low-intensity MBP group received secondary surgery, and two patients in the high-intensity MBP group received secondary surgery.

CONCLUSIONS

In this retrospective cohort, low-intensity MBP was associated with better PFS and OS, which could provide a reference for doctors when choosing the intensity of MBP.

Diet-gut microbial interactions influence cancer immunotherapy

The gut microbiome is involved in the absorption and metabolism of host nutrients and modulates the immune response, affecting the efficacy of immunotherapy for cancer. In patients receiving immunotherapy, appropriate modifications of gut microbiota are thought to improve therapeutic response. Of all the factors that influence the gut microbiota, diet is the most influential and modifiable. Healthy dietary patterns as well as some specific dietary components can help the growth of beneficial microbiota in the gut, thereby protecting against cancers and promoting human health. A growing number of researches have confirmed the positive effects of a diet-gut microbiota approach as an adjuvant therapy for cancer, but controversy remains. Here, we summarize the interactions between diet and gut microbes based on previous studies, and discuss the role of gut microbiota-based dietary strategies in tumor immunotherapy, with the potential mechanisms of actions also intensively discussed.

Fusobacterium nucleatum and its associated systemic diseases: epidemiologic studies and possible mechanisms

Background

Fusobacterium nucleatum (F. nucleatum) is an anaerobic oral commensal and the major coaggregation bridge organism linking early and late colonisers. In recent years, a large number of studies suggest that F. nucleatum is closely related to the development of various systemic diseases, such as cardiovascular diseases, adverse pregnancy outcomes, inflammatory bowel diseases, cancer, Alzheimer's disease, respiratory infection, rheumatoid arthritis, etc.

Objective

To review the effect of F. nucleatum on systemic diseases and its possible pathogenesis and to open new avenues for prevention and treatment of F. nucleatum-associated systemic diseases.

Design

The research included every article published up to July 2022 featuring the keywords 'Systemic diseases' OR 'Atherosclerotic cardiovascular diseases' OR 'Atherosclerosis' OR 'Adverse pregnancy outcomes' OR 'Inflammatory bowel disease' OR 'Ulcerative colitis' OR 'Crohn’s disease' OR 'Cancers' OR 'Oral squamous cell carcinomas' OR 'Gastrointestinal cancers' OR 'Colorectal cancer' OR 'Breast cancer' OR 'Genitourinary cancers' OR 'Alzheimer’s disease ' OR 'Rheumatoid arthritis' OR 'Respiratory diseases' AND 'Fusobacterium nucleatum' OR 'Periodontal pathogen' OR 'Oral microbiota' OR 'Porphyromonas gingivalis' and was conducted in the major medical databases.

Results

F. nucleatum can induce immune response and inflammation in the body through direct or indirect pathways, and thus affect the occurrence and development of systemic diseases. Only by continuing to investigate the pathogenic lifestyles of F. nucleatum will we discover the divergent pathways that may be leveraged for diagnostic, preventive and therapeutic purposes.

Implication of gut microbes and its metabolites in colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is the third most common cancer with a significant impact on loss of life. In 2020, nearly 1.9 million new cases and over 9,35,000 deaths were reported. Numerous microbes that are abundant in the human gut benefit host physiology in many ways. Although the underlying mechanism is still unknown, their association appears to be crucial in the beginning and progression of CRC. Diet has a significant impact on the microbial composition and may increase the chance of getting CRC. Increasing evidence points to the gut microbiota as the primary initiator of colonic inflammation, which is connected to the development of colonic tumors. However, it is unclear how the microbiota contributes to the development of CRCs. Patients with CRC have been found to have dysbiosis of the gut microbiota, which can be identified by a decline in commensal bacterial species, such as those that produce butyrate, and a concurrent increase in harmful bacterial populations, such as opportunistic pathogens that produce pro-inflammatory cytokines. We believe that using probiotics or altering the gut microbiota will likely be effective tools in the fight against CRC treatment.

PURPOSE

In this review, we revisited the association between gut microbiota and colorectal cancer whether cause or effect. The various factors which influence gut microbiome in patients with CRC and possible mechanism in relation with development of CRC.

CONCLUSION

The clinical significance of the intestinal microbiota may aid in the prevention and management of CRC.

Different Characteristics in Gut Microbiome between Advanced Adenoma Patients and Colorectal Cancer Patients by Metagenomic Analysis

The occurrence and development of colorectal cancer (CRC) and advanced adenoma (AA) are closely related to the gut microbiome, and AA has a high cancerization progression rate to CRC. Current studies have revealed that bacteriological analysis cannot identify CRC from AA. The objective was to explore microbial targets that could identify CRC and AA from a microecological perspective and to figure out the best way to identify CRC based on fecal microbes. The metagenomic sequencing data were used to describe the gut microbiome profile and analyze the differences between microbial abundance and microbial single nucleotide polymorphism (SNP) characteristics in AA and CRC patients. It was found that there were no significant differences in the diversity between the two groups. The abundance of bacteria (e.g., Firmicutes, Clostridia, and Blautia), fungi (Hypocreales), archaea (Methanosarcina, Methanoculleus, and Methanolacinia), and viruses (Alphacoronavirus, Sinsheimervirus, and Gammaretrovirus) differed between AA and CRC patients. Multiple machine-learning algorithms were used to establish prediction models, aiming to identify CRC and AA. The accuracy of the random forest (RF) model based on the gut microbiome was 86.54%. Nevertheless, the accuracy of SNP was 92.31% in identifying CRC from AA. In conclusion, using microbial SNP was the best method to identify CRC, it was superior to using the gut microbiome, and it could provide new targets for CRC screening. IMPORTANCE There are differences in characteristic microorganisms between AA and CRC. However, current studies have indicated that bacteriological analysis cannot identify CC from AA, and thus, we wondered if there were some other targets that could be used to identify CRC from AA in the gut microbiome. The differences of SNPs in the gut microbiota of intraindividuals were significantly smaller than those of interindividuals. In addition, compared with intestinal microbes, SNP was less affected by time with certain stability. It was discovered that microbial SNP was better than the gut microbiome for identifying CRC from AA. Therefore, screening characteristic microbial SNP could provide a new research direction for identifying CRC from AA.

Plant-based dietary patterns defined by a priori indices and colorectal cancer risk by sex and race/ethnicity: the Multiethnic Cohort Study

BACKGROUND

Plant-based diets assessed by a priori indices are associated with health outcomes. This study investigated the associations between pre-defined indices of plant-based diets and risk of colorectal cancer (CRC) and evaluated whether the association varies by sex, race and ethnicity, and anatomic subsite of tumors.

METHODS

A total of 79,952 men and 93,475 women who participated in the Multiethnic Cohort Study were included. Primary outcome was incidence of invasive CRC. Cox models were used to estimate the risk of CRC across quintiles of three plant-based diet scores: overall plant-based diet index (PDI), healthful plant-based diet index (hPDI), and unhealthful plant-based diet index (uPDI).

RESULTS

During a mean follow-up of 19.2 years, 4976 incident CRC were identified. Among men, multivariable-adjusted HR (95% CI) for the highest vs. lowest quintiles was 0.77 (0.67-0.88) for PDI, and 0.80 (0.70-0.91) for hPDI, while no significant association was found for uPDI among men and for all indices among women. In men, the inverse association for PDI was stronger in Japanese American, Native Hawaiian, and White groups than African American or Latino group (P for heterogeneity = 0.01) and for left colon and rectal tumors than right tumors (P for heterogeneity = 0.005), whereas the decreased risk with hPDI was found consistently across racial and ethnic groups and subsites.

CONCLUSIONS

Greater adherence to plant-based diets rich in healthy plant foods and low in less healthy plant foods is associated with a reduced risk of CRC in men, but not in women. The strength of the association among men may vary by race and ethnicity and anatomic subsite of tumors.

The Role of the Microbiome on the Pathogenesis and Treatment of Colorectal Cancer

The gut microbiome has long been known to play a role in various aspects of health modulation, including the pathogenesis of colorectal cancer (CRC). With immunotherapy recently emerging as a successful treatment in microsatellite instability high (MSI-high) CRC, and with a newly demonstrated involvement of the gut microbiome in the modulation of therapeutic responses, there has been an explosion of research into the mechanisms of microbial effects on CRC. Harnessing and reprogramming the microbiome may allow for the expansion of these successes to broader categories of CRC, the prevention of CRC in high-risk patients, and the enhancement of standard treatments. In this review, we pull together both well-documented phenomena and recent discoveries that pertain to the microbiome and CRC. We explore the microbial mechanisms associated with CRC pathogenesis and progression, recent advancements in CRC systemic therapy, potential options for diagnosis and prevention, as well as directions for future research.

Cross communication of diet-microbiome-immune interactions in cancer immunotherapy

Simpson et al. have highlighted a diet-driven microbiome community, which paves the way for landmark therapeutic avenues for facilitating efficacy and minimizing immune-related adverse events during neoadjuvant immune checkpoint inhibitor treatment in melanoma patients. This innovative attempt inspires application of the diet-microbiome-immune interaction axis to maximize clinical benefits.

Fusobacterium nucleatum stimulates cell proliferation and promotes PD-L1 expression via IFIT1-related signal in colorectal cancer

Fusobacterium nucleatum (F. nucleatum) is enriched in colorectal cancer (CRC) tissues and a high amount of F. nucleatum was associated with an immunosuppressive tumor environment. PD-L1 is an important immune checkpoint expressed on tumor cells and promotes tumor immune escape. Whether PD-L1 is regulated by F. nucleatum is still unclear. We demonstrated that F. nucleatum promoted CRC progression and upregulated PD-L1 protein expression in CRC cell lines. Combined m⁶A-seq and RNA-seq identified m⁶A-modified IFIT1 mediating F. nucleatum induced PD-L1 upregulation. IFIT1 mRNA was modified with m⁶A modifications in 3'UTR and the m⁶A levels were altered by F. nucleatum treatment. Our results also indicated that IFIT1 served as a potential oncogene in CRC and regulated PD-L1 protein levels through altering PD-L1 ubiquitination. Clinical CRC data confirmed the correlation among F. nucleatum abundance, IFIT1 and PD-L1 expressions. Our work highlighted the function of F. nucleatum in stimulating PD-L1 expression through m⁶A-modified IFIT1 and provided new aspects for understanding F. nucleatum mediated immune escape.

Sleep pattern, healthy lifestyle and colorectal cancer incidence

Researchers have identified an association between lifestyle factors and colorectal cancer (CRC) risk. This study examined the relationship between sleep patterns and CRC events. 392,252 individuals were sampled from the UK Biobank. Chronotype, sleep duration, insomnia, snoring, and excessive daytime sleepiness were combined to measure a healthy sleep score. A number of healthy sleep factors were defined, along with factors for healthy lifestyle scores. Using Cox proportional hazards regression, computed hazard ratios (HRs) were used to examine the associations between sleep patterns, healthy lifestyles, and the incidence of CRC. Healthy sleep scores were inversely associated with CRC events. The HRs for CRC were 0.90 (95% CI, 0.88-0.92) and 0.95 (95% CI, 0.92-0.98) for a 1-point healthy sleep score increase among males and females. When analyzing sleep components, sleeping 7-8 h/day, no frequent insomnia, no snoring, and no frequent daytime sleepiness were independently associated with a 9%, 14%, 8%, and 14% lower risk of CRC, respectively, whilst healthy lifestyle scores were inversely associated with CRC incidence across all models. Sleep pattern and lifestyle are significantly correlated with CRC risk. The healthier the subject's lifestyle and sleep pattern, the lower their CRC risk.

Host Genetics and Microbiota Interactions in Colorectal Cancer: Shared or Independent Risk?

The role of microbiota in colorectal cancer has been studied since alterations in its composition were observed. In addition, there are more and more pieces of evidence that microbiota could be implicated in colorectal cancer progression. Thus, the components of the microbiota could be biomarkers for the diagnosis and prognosis of colorectal cancer. In addition, it is important to address how the microbiota interacts with the host and how the host shapes the microbiota, in order to understand the biological pathways and mechanisms involved in their relationship and the consequences of their interactions in colorectal cancer. Thereby, it could be possible to find feasible measures and treatments to prevent or better diagnose colorectal cancer. In this review, we will try to summarize the role of the microbiota in colorectal cancer and its interactions with the host and the host genetics, coming to some conclusions that could be useful to find the gaps in our knowledge and propose future steps in this field.

Western-Style Diet, pks Island-Carrying Escherichia coli, and Colorectal Cancer: Analyses From Two Large Prospective Cohort Studies

BACKGROUND & AIMS

Evidence supports a carcinogenic role of Escherichia coli carrying the pks island that encodes enzymes for colibactin biosynthesis. We hypothesized that the association of the Western-style diet (rich in red and processed meat) with colorectal cancer incidence might be stronger for tumors containing higher amounts of pks+E coli.

METHODS

Western diet score was calculated using food frequency questionnaire data obtained every 4 years during follow-up of 134,775 participants in 2 United States-wide prospective cohort studies. Using quantitative polymerase chain reaction, we measured pks+E coli DNA in 1175 tumors among 3200 incident colorectal cancer cases that had occurred during the follow-up. We used the 3200 cases and inverse probability weighting (to adjust for selection bias due to tissue availability), integrated in multivariable-adjusted duplication-method Cox proportional hazards regression analyses.

RESULTS

The association of the Western diet score with colorectal cancer incidence was stronger for tumors containing higher levels of pks+E coli (Pheterogeneity = .014). Multivariable-adjusted hazard ratios (with 95% confidence interval) for the highest (vs lowest) tertile of the Western diet score were 3.45 (1.53-7.78) (Ptrend = 0.001) for pks+E coli-high tumors, 1.22 (0.57-2.63) for pks+E coli-low tumors, and 1.10 (0.85-1.42) for pks+E coli-negative tumors. The pks+E coli level was associated with lower disease stage but not with tumor location, microsatellite instability, or BRAF, KRAS, or PIK3CA mutations.

CONCLUSIONS

The Western-style diet is associated with a higher incidence of colorectal cancer containing abundant pks+E coli, supporting a potential link between diet, the intestinal microbiota, and colorectal carcinogenesis.

Human gut microbiota in health and disease: Unveiling the relationship

The human gut possesses millions of microbes that define a complex microbial community. The gut microbiota has been characterized as a vital organ forming its multidirectional connecting axis with other organs. This gut microbiota axis is responsible for host-microbe interactions and works by communicating with the neural, endocrinal, humoral, immunological, and metabolic pathways. The human gut microorganisms (mostly non-pathogenic) have symbiotic host relationships and are usually associated with the host’s immunity to defend against pathogenic invasion. The dysbiosis of the gut microbiota is therefore linked to various human diseases, such as anxiety, depression, hypertension, cardiovascular diseases, obesity, diabetes, inflammatory bowel disease, and cancer. The mechanism leading to the disease development has a crucial correlation with gut microbiota, metabolic products, and host immune response in humans. The understanding of mechanisms over gut microbiota exerts its positive or harmful impacts remains largely undefined. However, many recent clinical studies conducted worldwide are demonstrating the relation of specific microbial species and eubiosis in health and disease. A comprehensive understanding of gut microbiota interactions, its role in health and disease, and recent updates on the subject are the striking topics of the current review. We have also addressed the daunting challenges that must be brought under control to maintain health and treat diseases.

Patients with mesenchymal tumours and high Fusobacteriales prevalence have worse prognosis in colorectal cancer (CRC)

OBJECTIVES

Transcriptomic-based subtyping, consensus molecular subtyping (CMS) and colorectal cancer intrinsic subtyping (CRIS) identify a patient subpopulation with mesenchymal traits (CMS4/CRIS-B) and poorer outcome. Here, we investigated the relationship between prevalence of Fusobacterium nucleatum (Fn) and Fusobacteriales, CMS/CRIS subtyping, cell type composition, immune infiltrates and host contexture to refine patient stratification and to identify druggable context-specific vulnerabilities.

DESIGN

We coupled cell culture experiments with characterisation of Fn/Fusobacteriales prevalence and host biology/microenviroment in tumours from two independent colorectal cancer patient cohorts (Taxonomy: n=140, colon and rectal cases of The Cancer Genome Atlas (TCGA-COAD-READ) cohort: n=605).

RESULTS

In vitro, Fn infection induced inflammation via nuclear factor kappa-light-chain-enhancer of activated B cells/tumour necrosis factor alpha in HCT116 and HT29 cancer cell lines. In patients, high Fn/Fusobacteriales were found in CMS1, microsatellite unstable () tumours, with infiltration of M1 macrophages, reduced M2 macrophages, and high interleukin (IL)-6/IL-8/IL-1β signalling. Analysis of the Taxonomy cohort suggested that Fn was prognostic for CMS4/CRIS-B patients, despite having lower Fn load than CMS1 patients. In the TCGA-COAD-READ cohort, we likewise identified a differential association between Fusobacteriales relative abundance and outcome when stratifying patients in mesenchymal (either CMS4 and/or CRIS-B) versus non-mesenchymal (neither CMS4 nor CRIS-B). Patients with mesenchymal tumours and high Fusobacteriales had approximately twofold higher risk of worse outcome. These associations were null in non-mesenchymal patients. Modelling the three-way association between Fusobacteriales prevalence, molecular subtyping and host contexture with logistic models with an interaction term disentangled the pathogen-host signalling relationship and identified aberrations (including NOTCH, CSF1-3 and IL-6/IL-8) as candidate targets.

CONCLUSION

This study identifies CMS4/CRIS-B patients with high Fn/Fusobacteriales prevalence as a high-risk subpopulation that may benefit from therapeutics targeting mesenchymal biology.

Healthy and unhealthy plant-based diets in relation to the incidence of colorectal cancer overall and by molecular subtypes

BACKGROUND

Plant-based foods have been recommended for health. However, not all plant foods are healthy, and little is known about the association between plant-based diets and specific molecular subtypes of colorectal cancer (CRC). We examined the associations of healthy and unhealthy plant-based diets with the incidence of CRC and its molecular subtypes.

METHODS

While 123 773 participants of the Nurses' Health Study and the Health Professionals Follow-up Study had been followed up (3 143 158 person-years), 3077 of them had developed CRC. Healthy and unhealthy plant-based diet indices (hPDI and uPDI, respectively) were calculated using repeated food frequency questionnaire data. We determined the tumoural status of microsatellite instability (MSI), CpG island methylator phenotype (CIMP), and BRAF and KRAS mutations.

RESULTS

Higher hPDI was associated with lower CRC incidence (multivariable hazard ratio [HR] comparing extreme quartiles, 0.86, 95% confidence interval [CI]: 0.77, 0.96; P-trend = .04), whereas higher uPDI was associated with higher CRC incidence (multivariable HR comparing extreme quartiles, 1.16, 95% CI: 1.04, 1.29; P-trend = .005). The association of hPDI significantly differed by KRAS status (P-heterogeneity = .003) but not by other tumour markers. The hPDI was associated with lower incidence of KRAS-wildtype CRC (multivariable HR comparing extreme quartiles, 0.74, 95% CI: 0.57, 0.96; P-trend = .004) but not KRAS-mutant CRC (P-trend = .22).

CONCLUSIONS

While unhealthy plant-based diet enriched with refined grains and sugar is associated with higher CRC incidence, healthy plant-based diet rich in whole grains, fruits and vegetables is associated with lower incidence of CRC, especially KRAS-wildtype CRC.

Structural and Functional Analysis of the Pyridoxal Phosphate Homeostasis Protein YggS from Fusobacterium nucleatum

Pyridoxal 5′-phosphate (PLP) is the active form of vitamin B6, but it is highly reactive and poisonous in its free form. YggS is a PLP-binding protein found in bacteria and humans that mediates PLP homeostasis by delivering PLP to target enzymes or by performing a protective function. Several biochemical and structural studies of YggS have been reported, but the mechanism by which YggS recognizes PLP has not been fully elucidated. Here, we report a functional and structural analysis of YggS from Fusobacterium nucleatum (FnYggS). The PLP molecule could bind to native FnYggS, but no PLP binding was observed for selenomethionine (SeMet)-derivatized FnYggS. The crystal structure of FnYggS showed a type III TIM barrel fold, exhibiting structural homology with several other PLP-dependent enzymes. Although FnYggS exhibited low (<35%) amino acid sequence similarity with previously studied YggS proteins, its overall structure and PLP-binding site were highly conserved. In the PLP-binding site of FnYggS, the sulfate ion was coordinated by the conserved residues Ser201, Gly218, and Thr219, which were positioned to provide the binding moiety for the phosphate group of PLP. The mutagenesis study showed that the conserved Ser201 residue in FnYggS was the key residue for PLP binding. These results will expand the knowledge of the molecular properties and function of the YggS family.

Cancer as microenvironmental, systemic and environmental diseases: opportunity for transdisciplinary microbiomics science

Cancer is generally regarded as a localised disease, with the well-established role of the tumour microenvironment. However, the realm of cancer goes beyond the tumour microenvironment, and cancer should also be regarded as a systemic and environmental disease. The exposome (ie, the totality of exposures), which encompasses diets, supplements, smoking, alcohol, other lifestyle factors, medications, etc, likely alters the microbiome (inclusive of bacteria, viruses, archaea, fungi, parasites, etc) and immune system in various body sites and influences tumour phenotypes. The systemic metabolic/inflammatory status, which is likely influenced by exposures and intestinal physiological changes, may affect tissue microenvironment of colorectum and any other organs. Germline genomic factors can modify disease phenotypes via gene-by-environment interactions. Although challenges exist, it is crucial to advance not only basic experimental research that can analyse the effects of exposures, microorganisms and microenvironmental components on tumour evolution but also interdisciplinary human population research that can dissect the complex pathogenic roles of the exposome, microbiome and immunome. Metagenomic, metatranscriptomic and metabolomic analyses should be integrated into well-designed population research combined with advanced methodologies of artificial intelligence and molecular pathological epidemiology. Ideally, a prospective cohort study design that enables biospecimen (such as stool) collection before disease detection should be considered to address reverse causation and recall biases. Robust experimental and observational research together can provide insights into dynamic interactions between environmental exposures, microbiota, tumour and immunity during carcinogenesis processes, thereby helping us develop precision prevention and therapeutic strategies to ultimately reduce the cancer burden.

Dietary modulation of gut microbiota in patients with colorectal cancer undergoing surgery: A review

Colorectal cancer (CRC) is the third most frequent malignancy and the second cause of cancer death worldwide. Several factors have been postulated to be involved in CRC pathophysiology, including physical inactivity, unhealthy dietary habits, obesity, and the gut microbiota. Emerging data suggest that the microbiome may play a key role in CRC prognosis and derived complications in patients undergoing colorectal surgery. On the other hand, dietary intervention has been demonstrated to be able to induce significant changes in the gut microbiota and related metabolites in different conditions; therefore, the manipulation of gut microbiota through dietary intervention may constitute a useful approach to improve perioperative dysbiosis and post-surgical outcomes in patients with CRC. In this article, we review the role of the gut microbiota in CRC surgery complications and the potential therapeutic modulation of gut microbiome through nutritional intervention in patients with CRC undergoing surgery.

Aspirin sensitivity of PIK3CA-mutated Colorectal Cancer: potential mechanisms revisited

PIK3CA mutations are amongst the most prevalent somatic mutations in cancer and are associated with resistance to first-line treatment along with low survival rates in a variety of malignancies. There is evidence that patients carrying PIK3CA mutations may benefit from treatment with acetylsalicylic acid, commonly known as aspirin, particularly in the setting of colorectal cancer. In this regard, it has been clarified that Class IA Phosphatidylinositol 3-kinases (PI3K), whose catalytic subunit p110α is encoded by the PIK3CA gene, are involved in signal transduction that regulates cell cycle, cell growth, and metabolism and, if disturbed, induces carcinogenic effects. Although PI3K is associated with pro-inflammatory cyclooxygenase-2 (COX-2) expression and signaling, and COX-2 is among the best-studied targets of aspirin, the mechanisms behind this clinically relevant phenomenon are still unclear. Indeed, there is further evidence that the protective, anti-carcinogenic effect of aspirin in this setting may be mediated in a COX-independent manner. However, until now the understanding of aspirin's prostaglandin-independent mode of action is poor. This review will provide an overview of the current literature on this topic and aims to analyze possible mechanisms and targets behind the aspirin sensitivity of PIK3CA-mutated cancers.