Role of Fusobacteria in the serrated pathway of colorectal carcinogenesis

Biological and Clinical Characteristics of Proximal Colon Cancer: Far from Its Anatomical Subsite

Colorectal cancer is a heterogeneous disease which can be divided into proximal colon cancer, distal colon cancer and rectal cancer according to the anatomical location of the tumor. Each anatomical location of colorectal cancer exhibits distinct characteristics in terms of incidence, clinical manifestations, molecular phenotypes, treatment, and prognosis. Notably, proximal colon cancer differs significantly from cancers of other anatomical subsites. An increasing number of studies have highlighted the presence of unique tumor biological characteristics in proximal colon cancer. Gaining a deeper understanding of these characteristics will facilitate accurate diagnosis and treatment approaches.

Unravelling the role of intratumoral bacteria in digestive system cancers: current insights and future perspectives

Recently, research on the human microbiome, especially concerning the bacteria within the digestive system, has substantially advanced. This exploration has unveiled a complex interplay between microbiota and health, particularly in the context of disease. Evidence suggests that the gut microbiome plays vital roles in digestion, immunity and the synthesis of vitamins and neurotransmitters, highlighting its significance in maintaining overall health. Conversely, disruptions in these microbial communities, termed dysbiosis, have been linked to the pathogenesis of various diseases, including digestive system cancers. These bacteria can influence cancer progression through mechanisms such as DNA damage, modulation of the tumour microenvironment, and effects on the host's immune response. Changes in the composition and function within the tumours can also impact inflammation, immune response and cancer therapy effectiveness. These findings offer promising avenues for the clinical application of intratumoral bacteria for digestive system cancer treatment, including the potential use of microbial markers for early cancer detection, prognostication and the development of microbiome-targeted therapies to enhance treatment outcomes. This review aims to provide a comprehensive overview of the pivotal roles played by gut microbiome bacteria in the development of digestive system cancers. Additionally, we delve into the specific contributions of intratumoral bacteria to digestive system cancer development, elucidating potential mechanisms and clinical implications. Ultimately, this review underscores the intricate interplay between intratumoral bacteria and digestive system cancers, underscoring the pivotal role of microbiome research in transforming diagnostic, prognostic and therapeutic paradigms for digestive system cancers.

Unveiling the Gastrointestinal Microbiome Symphony: Insights Into Post-Gastric Cancer Treatment Microbial Patterns and Potential Therapeutic Avenues

This review delved into the intricate relationship between the gastrointestinal microbiome and gastric cancer, particularly focusing on post-treatment alterations, notably following gastrectomy, and the effects of anticancer therapies. Following gastrectomy, analysis of fecal samples revealed an increased presence of oral cavity aerotolerant and bile acid-transforming bacteria in the intestine. Similar changes were observed in the gastric microbiome, highlighting significant alterations in taxon abundance and emphasizing the reciprocal interaction between the oral and gastric microbiomes. In contrast, the impact of chemotherapy and immunotherapy on the gut microbiome was subtle, although discernible differences were noted between treatment responders and non-responders. Certain bacterial taxa showed promise as potential prognostic markers. Notably, probiotics emerged as a promising approach for postgastrectomy recovery, displaying the capacity to alleviate inflammation, bolster immune responses, and maintain a healthy gut microbiome. Several strains, including Bifidobacterium, Lactobacillus, and Clostridium butyricum, exhibited favorable outcomes in postoperative patients, suggesting their potential roles in comprehensive patient care. In conclusion, understanding the intricate interplay between the gastrointestinal microbiome and gastric cancer treatment offers prospects for predicting responses and enhancing postoperative recovery. Probiotics, with their positive impact on inflammation and immunity, have emerged as potential adjuncts in patient care. Continued research is imperative to fully harness the potential of microbiome-based interventions in the management of gastric cancer.

Tissue vs. Fecal-Derived Bacterial Dysbiosis in Precancerous Colorectal Lesions: A Systematic Review

Alterations in gut microbiota play a pivotal role in the adenoma-carcinoma sequence. However, there is still a notable lack of the correct implementation of tissue and fecal sampling in the setting of human gut microbiota examination. This study aimed to review the literature and to consolidate the current evidence on the use of mucosa and a stool-based matrix investigating human gut microbiota changes in precancerous colorectal lesions. A systematic review of papers from 2012 until November 2022 published on the PubMed and Web of Science databases was conducted. The majority of the included studies have significantly associated gut microbial dysbiosis with premalignant polyps in the colorectum. Although methodological differences hampered the precise fecal and tissue-derived dysbiosis comparison, the analysis revealed several common characteristics in stool-based and fecal-derived gut microbiota structures in patients with colorectal polyps: simple or advanced adenomas, serrated lesions, and carcinomas in situ. The mucosal samples considered were more relevant for the evaluation of microbiota's pathophysiological involvement in CR carcinogenesis, while non-invasive stool sampling could be beneficial for early CRC detection strategies in the future. Further studies are required to identify and validate mucosa-associated and luminal colorectal microbial patterns and their role in CRC carcinogenesis, as well as in the clinical setting of human microbiota studies.

The role of Fusobacteria in oral cancer and immune evasion

PURPOSE OF REVIEW

There is growing evidence that suggests a possible role for bacteria in the progression of cancer. Fusobacteria have been detected in different types of cancers, including colorectal and oral cancers. Fusobacteria are common opportunistic oral bacteria known to cause various infections. In this review, we focus on the association between Fusobacteria and cancer, specifically oral cancer, and provide insight into the role of Fusobacteria in carcinogenesis and immune evasion.

RECENT FINDINGS

Recently, it has been suggested that Fusobacteria are among the bacteria that contribute to the progression of cancer and might affect disease prognosis and treatment outcome. Moreover, Fusobacteria might alter tumor microenvironment and have an impact on tumor immune response. Thus, understanding the effect of Fusobacteria on cancer cells and tumor microenvironment is crucial to improve treatment outcome.

SUMMERY

Recent evidences suggest that Fusobacteria not only have an impact on tumor progression, but might also affect tumor immune response. Moreover, Fusobacteria presence in the tumor microenvironment might have an impact on treatment outcome and might be used as a prognostic factor.

Fusobacterium nucleatum and colorectal cancer: From phenomenon to mechanism

Colorectal cancer(CRC) is the third most frequent malignant tumor. The gut microbiome acts as a vital component of CRC etiology. Fusobacterium nucleatum(Fn) is a key member of colorectal cancer-associated bacteria. But we lack a systematic and in-depth understanding on its role in CRC evolution. In this article, We reviewed the abundance changes and distribution of Fn in CRC occurrence and development, potential effect of Fn in the initiation of CRC, the source of intratumoral Fn and the cause of its tropism to CRC. In addition, We described the mechanism by which Fn promotes the malignant biological behavior of CRC, affects CRC response to therapy, and shapes the tumor immune microenvironment in great detail. Based on the relationship between Fn and CRC, we proposed strategies for CRC prevention and treatment, and discussed the feasibility and limitations of specific cases, to gain insights into further basic and clinical research in the future.

Inflammation, microbiome and colorectal cancer disparity in African-Americans: Are there bugs in the genetics?

Dysregulated interactions between host inflammation and gut microbiota over the course of life increase the risk of colorectal cancer (CRC). While environmental factors and socio-economic realities of race remain predominant contributors to CRC disparities in African-Americans (AAs), this review focuses on the biological mediators of CRC disparity, namely the under-appreciated influence of inherited ancestral genetic regulation on mucosal innate immunity and its interaction with the microbiome. There remains a poor understanding of mechanisms linking immune-related genetic polymorphisms and microbiome diversity that could influence chronic inflammation and exacerbate CRC disparities in AAs. A better understanding of the relationship between host genetics, bacteria, and CRC pathogenesis will improve the prediction of cancer risk across race/ethnicity groups overall.

Microbiome Analysis in Patients with Colorectal Cancer by 16S Ribosomal RNA Sequencing in the Southeast of Iran

Background: Colorectal cancer (CRC) is the third most common malignant tumor worldwide. Emerging evidence suggests that dysbiosis of the colon microbiome may be involved in CRC development. Objectives: The present study aimed to compare the composition and diversity of the colon microbiome by high-throughput 16S ribosomal RNA (rRNA) sequencing between CRC patients and healthy controls. Microbiome composition and diversity were also examined based on gender. Methods: The colon microbiome richness and diversity of samples from 17 CRC patients and 13 healthy controls were analyzed by 16S rRNA sequencing. Alpha and beta diversity were calculated to determine the differences in colon microbiome diversity. Results: Alpha and beta diversity showed significant differences between the CRC and healthy control groups regarding the microbiome. Our results showed that CRC samples had the highest richness and diversity. The total number (P ≤ 0.01), phylogenetic diversity (P ≤ 0.01), Chao1 (P ≤ 0.01), Shannon (P ≤ 0.05), and Simpson (P ≤ 0.01) indices were significantly higher in the CRC group than in the healthy control group. In addition, the comparison between females and males showed that the microbiome diversity was higher in the CRC female (CRC-F) group than in other groups. Prevotella, Fusobacterium, Akkermansia, Leptotrichia, Streptococcus, and ParaBacteroides were more commonly observed in the CRC group, while Bacteroides, Enterobacteriaceae (unknown genus), Ruminococcus, and Campylobacter were more commonly observed in the healthy control group. Conclusions: This study showed differences between the CRC and healthy control groups regarding the diversity and composition of the colon microbiome, suggesting a contribution of the microbiome in the development and progression of CRC.

Berberine inhibits intestinal carcinogenesis by suppressing intestinal pro-inflammatory genes and oncogenic factors through modulating gut microbiota

BACKGROUND

The role of Berberine (BBR) in colorectal cancer (CRC) and gut microbiota has begun to appreciate. However, there was no direct evidence confirm that the gut microbiota regulated by BBR could inhibit CRC. This report investigated the effect of stool from BBR treated subjects and its effect on CRC.

METHODS

A mouse model for CRC was developed using azoxymethane (AOM) and dextran sulfate sodium (DSS). Intestinal tissue from affected mice were used to determine the efficacy of BBR against CRC. Stool samples were collected for the 16s rRNA gene sequencing and fecal microbiota transplantation (FMT). Finally, the mechanism of gut microbiota from BBR treated mice on CRC was explored using immunohistochemistry, RNA-Sequencing, quantitative RT-PCR, and western blot analyses.

RESULTS

BBR significantly reduced intestinal tumor development. The richness of gut microbiota were notably decreased by BBR. Specifically, the relative abundance of beneficial bacteria (Roseburia, Eubacterium, Ruminococcaceae, and Firmicutes_unclassified) was increased while the level of bacteria (Odoribacter, Muribaculum, Mucispirillum, and Parasutterella) was decreased by BBR treatment. FMT experiment determined that the mice fed with stool from BBR treated AOM/DSS mice demonstrated a relatively lower abundance of macroscopic polyps and a significantly lower expression of β-catenin, and PCNA in intestinal tissue than mice fed with stool from AOM/DSS mice. Mechanistically, intestinal tissue obtained from mice fed with stool from BBR treated AOM/DSS mice demonstrated a decreased expression of inflammatory cytokines including interleukin 1β (IL-1β), tumor necrosis factor-α (TNF-α), C-C motif chemokine 1 (Ccl1), Ccl6, and C-X-C motif ligand (Cxcl9). In addition, the NF-κB expression was greatly suppressed in mice fed with stool from BBR treated AOM/DSS mice. Real-time PCR arrays revealed a down-regulation of genes involved in cell proliferation, angiogenesis, invasiveness, and metastasis in mice fed with stool from BBR treated AOM/DSS mice.

CONCLUSIONS

Stool obtained from BBR treated AOM/DSS mice was able to increase colon length while simultaneously decreasing the density of macroscopic polyps, cell proliferation, inflammatory modulators and the expression of NF-κB. Therefore, it was concluded that suppression of pro-inflammatory genes and carcinogens factors by modulating gut microbiota was an important pathway for BBR to inhibit tumor growth in conventional mice.

Acute effects of antimony exposure on adult zebrafish (Danio rerio): From an oxidative stress and intestinal microbiota perspective

The rapid development of the textile industry has resulted in a large influx of wastewater production. The "national discharge standards of water pollutants for dyeing and finishing of textile industry (GB4287-2012)" stipulates that the discharge of total Sb from textile industry effluent must be < 0.10 mg/L, but it is difficult to meet the standard at present. Antimony is potentially carcinogenic, and the pathogenic mechanism of antimony is poorly understood. In this study, the acute toxic effects of various concentrations of antimony on adult zebrafish (Danio rerio) were investigated, including effects on oxidative stress, neurotransmitters and intestinal microbiota. The activities of catalase (CAT), glutathione peroxidase (GSH-Px), malondialdehyde (MDA), superoxide dismutase (SOD), total antioxidant capacity (T-AOC) and acetylcholinesterase (AChE) were measured in zebrafish muscle and intestine tissue samples. In addition, intestinal microbial community composition and diversity of zebrafish were also analyzed. The results demonstrated that SOD, CAT and GSH-Px activities in the zebrafish gut showed a decreasing and then increasing trend with antimony concentration increasing. SOD, CAT and MDA in zebrafish muscle decreased with increasing exposure time. GSH-Px activities increased with increasing exposure time. T-AOC increased and then decreased. In addition, antimony exposure was neurotoxic to zebrafish, and a significant decrease in AChE activity was found in the intestine with increased exposure time. The neurotoxicity caused by antimony in the high concentration group (40 mg/L) was stronger than that in low concentration groups (10 mg/L and 20 mg/L). Notably, antimony exposure caused increases in the relative abundance of phyla Fusobacteriota and Actinomycetes, but decreases in the relative abundance of the phyla Firmicutes and Proteobacteria in zebrafish intestine. These outcomes will advance our understanding of antimony-induced biotoxicity, environmental problems, and health hazards. In conclusion, this study shows that acute exposure of antimony to zebrafish induces host oxidative stress and neurotoxicity, dysregulates the intestinal microbiota, showing adverse effects on the health and gut microbiota of zebrafish.

Serrated neoplasia in the colorectum: gut microbiota and molecular pathways

Colorectal cancer (CRC) is a heterogeneous disease with different gene expression patterns. There are two major colorectal carcinogenesis pathways: conventional adenoma-carcinoma pathway and alternative serrated neoplasia pathway. Apart from the conventional pathway that is typically initiated by characteristic APC mutation and chromosomal instability, the serrated neoplasia pathway is mainly characterized by mutations of BRAF or KRAS, microsatellite instability (MSI), and CpG island methylator phenotype (CIMP). Despite the malignant potential of serrated lesions, they can be easily overlooked during endoscopy screening and even in pathological assessment due to its anatomical location, morphology, and histological features. It has been shown that environmental factors especially the gut microbial composition play a key role in CRC pathogenesis. Thus, the preferential localization of serrated lesions in specific intestine areas suggest that niche-specific microbiota composition might intertwined with host genetic perturbations during the development of serrated lesions. Although serrated lesions and conventional adenomas are biologically different, most studies have focused on conventional adenomas, while the pathophysiology and role of microorganisms in the development of serrated lesions remain elusive. In this review, we discuss on the role of gut microbiota in the serrated neoplasia pathway of colorectal carcinogenesis and its specific clinical and molecular features, and summarize the potential mechanisms involved.

Oral Bacterial Microbiota in Digestive Cancer Patients: A Systematic Review

The relation between the gut microbiota and human health is increasingly recognized. Recently, some evidence suggested that dysbiosis of the oral microbiota may be involved in the development of digestive cancers. A systematic review was conducted according to the PRISMA guidelines to investigate the association between the oral microbiota and digestive cancers. Several databases including Medline, Scopus, and Embase were searched by three independent reviewers, without date restriction. Over a total of 1654 records initially identified, 28 studies (2 prospective cohort studies and 26 case-controls) were selected. They investigated oral microbiota composition in patients with esophageal squamous cell carcinoma (n = 5), gastric cancer (n = 5), colorectal cancer (n = 9), liver carcinoma (n = 2), and pancreatic cancer (n = 7). In most of the studies, oral microbiota composition was found to be different between digestive cancer patients and controls. Particularly, oral microbiota dysbiosis and specific bacteria, such as Fusobacterium nucleatum and Porphyromonas gingivalis, appeared to be associated with colorectal cancers. Current evidence suggests that differences exist in oral microbiota composition between patients with and without digestive cancers. Further studies are required to investigate and validate oral-gut microbial transmission patterns and their role in digestive cancer carcinogenesis.

Wheat Breeding, Fertilizers, and Pesticides: Do They Contribute to the Increasing Immunogenic Properties of Modern Wheat?

Celiac disease (CD) is a small intestinal inflammatory condition where consumption of gluten induces a T-cell mediated immune response that damages the intestinal mucosa in susceptible individuals. CD affects at least 1% of the world’s population. The increasing prevalence of CD has been reported over the last few decades. However, the reason for this increase is not known so far. Certain factors such as increase in awareness and the development of advanced and highly sensitive diagnostic screening markers are considered significant factors for this increase. Wheat breeding strategies, fertilizers, and pesticides, particularly herbicides, are also thought to have a role in the increasing prevalence. However, less is known about this issue. In this review, we investigated the role of these agronomic practices in depth. Our literature-based results showed that wheat breeding, use of nitrogen-based fertilizers, and herbicides cannot be solely responsible for the increase in celiac prevalence. However, applying nitrogen fertilizers is associated with an increase in gluten in wheat, which increases the risk of developing celiac-specific symptoms in gluten-sensitive individuals. Additionally, clustered regularly interspaced short palindromic repeats (CRISPR) techniques can edit multiple gliadin genes, resulting in a low-immunogenic wheat variety that is safe for such individuals.

Identification and Validation of Potential Candidate Genes of Colorectal Cancer in Response to Fusobacterium nucleatum Infection

Objective: Recent investigations revealed the relationship between Fusobacterium nucleatum (Fn) infection and colorectal cancer (CRC). However, how the host genes changes contribute to CRC in response to Fn infection remains largely unknown.

Materials and methods: In the present study, we aimed to comprehensively analyze microarray data obtained from a Caco-2 infection cell model using integrated bioinformatics analysis and further identify and validate potential candidate genes in Fn-infected Caco-2 cells and CRC specimens.

Results: We identified 10 hub genes potentially involved in Fn induced tumor initiation and progression. Furthermore, we demonstrated that the expression of centrosomal protein of 55 kDa (CEP55) is significantly higher in Fn-infected Caco-2 cells. Knocking down of CEP55 could arrest the cell cycle progression and induce apoptosis in Fn-infected Caco-2 cells. The expression of CEP55 was positively correlated with the Fn amount in Fn-infected CRC patients, and these patients with high CEP55expression had an obviously poorer differentiation, worse metastasis and decreased cumulative survival rate.

Conclusion: CEP55 plays an important role in Fn-infected colon cancer cell growth and cell cycle progression and could be used as a new diagnostic and prognostic biomarker for Fn-infected CRC.

Microbiota Alterations in Precancerous Colon Lesions: A Systematic Review

Simple Summary

Even with recent advances, gut microbiota is still one of the most demanding challenges that research needs to handle. In particular, given its deep impact on gastrointestinal health, microbiota could explain the development and progression of certain diseases. Moreover, it could be used as a potential predictive biomarker. Given this, the relationship between intestinal microbiota and colorectal adenoma, considered a premalignant lesion leading to carcinoma, has been deeply evaluated. This review highlights the historical and novel data on microbiota characteristics in adenoma patients to provide an updated summary of current knowledge and its limits.

Abstract

Gut microbiota plays an important role in human health. It may promote carcinogenesis and is related to several diseases of the gastrointestinal tract. This study of microbial dysbiosis in the etiology of colorectal adenoma aimed to investigate the possible causative role of microbiota in the adenoma–carcinoma sequence and its possible preventive role. A systematic, PRISMA-guided review was performed. The PubMed database was searched using “adenoma microbiota” and selecting original articles between January 2010 and May 2020 independently screened. A higher prevalence of Proteobacteria, Fusobacteria, and Bacteroidetes phyla was observed in the fecal luminal and mucosa-associated microbiota of patients with adenoma. However, other studies provided evidence of depletion of Clostridium, Faecalibacterium, Bacteroides and Romboutsia. Results on the relationship between adenoma endoscopic resection and microbiota were inconsistent. In conclusion, none of the analyzed studies developed a predictive model that could differentiate adenoma from non-adenoma patients, and therefore, to prevent cancer progression. The impact of adenoma’s endoscopic resection on microbiota was investigated, but the results were inconclusive. Further research in the field is required.

Relationship between microsatellite status and immune microenvironment of colorectal cancer and its application to diagnosis and treatment

Due to advances in understanding the immune microenvironment of colorectal cancer (CRC), microsatellite classification (dMMR/MSI-H and pMMR/MSS) has become a key biomarker for the diagnosis and treatment of CRC patients and therefore has important clinical value. Microsatellite status is associated with a variety of clinicopathological features and affects drug resistance and the prognosis of patients. CRC patients with different microsatellite statuses have different compositions and distributions of immune cells and cytokines within their tumor microenvironments (TMEs). Therefore, there is great interest in reversing or reshaping CRC TMEs to transform immune tolerant "cold" tumors into immune sensitive "hot" tumors. This requires a thorough understanding of differences in the immune microenvironments of MSI-H and MSS type tumors. This review focuses on the relationship between CRC microsatellite status and the immune microenvironment. It focuses on how this relationship has value for clinical application in diagnosis and treatment, as well as exploring the limitations of its current application.

Significant and Conflicting Correlation of IL-9 With Prevotella and Bacteroides in Human Colorectal Cancer

Background and aim

Gut microbiota (GM) can support colorectal cancer (CRC) progression by modulating immune responses through the production of both immunostimulatory and/or immunosuppressive cytokines. The role of IL-9 is paradigmatic because it can either promote tumor progression in hematological malignancies or inhibit tumorigenesis in solid cancers. Therefore, we investigate the microbiota–immunity axis in healthy and tumor mucosa, focusing on the correlation between cytokine profile and GM signature.

Methods

In this observational study, we collected tumor (CRC) and healthy (CRC-S) mucosa samples from 45 CRC patients, who were undergoing surgery in 2018 at the Careggi University Hospital (Florence, Italy). First, we characterized the tissue infiltrating lymphocyte subset profile and the GM composition. Subsequently, we evaluated the CRC and CRC-S molecular inflammatory response and correlated this profile with GM composition, using Dirichlet multinomial regression.

Results

CRC samples displayed higher percentages of Th17, Th2, and Tregs. Moreover, CRC tissues showed significantly higher levels of MIP-1α, IL-1α, IL-1β, IL-2, IP-10, IL-6, IL-8, IL-17A, IFN-γ, TNF-α, MCP-1, P-selectin, and IL-9. Compared to CRC-S, CRC samples also showed significantly higher levels of the following genera: Fusobacteria, Proteobacteria, Fusobacterium, Ruminococcus2, and Ruminococcus. Finally, the abundance of Prevotella spp. in CRC samples negatively correlated with IL-17A and positively with IL-9. On the contrary, Bacteroides spp. presence negatively correlated with IL-9.

Conclusions

Our data consolidate antitumor immunity impairment and the presence of a distinct microbiota profile in the tumor microenvironment compared with the healthy mucosa counterpart. Relating the CRC cytokine profile with GM composition, we confirm the presence of bidirectional crosstalk between the immune response and the host’s commensal microorganisms. Indeed, we document, for the first time, that Prevotella spp. and Bacteroides spp. are, respectively, positively and negatively correlated with IL-9, whose role in CRC development is still under debate.

Microbiome distinctions between the CRC carcinogenic pathways

Colorectal cancer (CRC) is the third most commonly diagnosed cancer, the third leading cause of cancer-related deaths, and has been on the rise among young adults in the United States. Research has established that the colonic microbiome is different in patients with CRC compared to healthy controls, but few studies have investigated if and how the microbiome may relate to CRC progression through the serrated pathway versus the adenoma-carcinoma sequence.Our view is that progress in CRC microbiome research requires consideration of how the microbiome may contribute to CRC carcinogenesis through the distinct pathways that lead to CRC, which could enable the creation of novel and tailored prevention, screening, and therapeutic interventions. We first highlight the limitations in existing CRC microbiome research and offer corresponding solutions for investigating the microbiome's role in the adenoma-carcinoma sequence and serrated pathway. We then summarize the findings in the select human studies that included data points related to the two major carcinogenic pathways. These studies investigate the microbiome in CRC carcinogenesis and 1) utilize mucosal samples and 2) compare polyps or tumors by histopathologic type, molecular/genetic type, or location in the colon.Key findings from these studies include: 1) Fusobacterium is associated with right-sided, more advanced, and serrated lesions; 2) the colons of people with CRC have bacteria typically associated with normal oral flora; and 3) colons from people with CRC have more biofilms, and these biofilms are predominantly located in the proximal colon (single study).

BRAFV600E mutation impinges on gut microbial markers defining novel biomarkers for serrated colorectal cancer effective therapies

BACKGROUND

Colorectal cancer (CRC) harboring BRAF^V600E mutation exhibits low response to conventional therapy and poorest prognosis. Due to the emerging correlation between gut microbiota and CRC carcinogenesis, we investigated in serrated BRAF^V600E cases the existence of a peculiar fecal microbial fingerprint and specific bacterial markers, which might represent a tool for the development of more effective clinical strategies.

METHODS

By injecting human CRC stem-like cells isolated from BRAF^V600E patients in immunocompromised mice, we described a new xenogeneic model of this subtype of CRC. By performing bacterial 16S rRNA sequencing, the fecal microbiota profile was then investigated either in CRC-carrying mice or in a cohort of human CRC subjects. The microbial communities' functional profile was also predicted. Data were compared with Mann-Whitney U, Welch's t-test for unequal variances and Kruskal-Wallis test with Benjamini-Hochberg false discovery rate (FDR) correction, extracted as potential BRAF class biomarkers and selected as model features. The obtained mean test prediction scores were subjected to Receiver Operating characteristic (ROC) analysis. To discriminate the BRAF status, a Random Forest classifier (RF) was employed.

RESULTS

A specific microbial signature distinctive for BRAF status emerged, being the BRAF-mutated cases closer to healthy controls than BRAF wild-type counterpart. In agreement, a considerable score of correlation was also pointed out between bacteria abundance from BRAF-mutated cases and the level of markers distinctive of BRAF^V600E pathway, including those involved in inflammation, innate immune response and epithelial-mesenchymal transition. We provide evidence that two candidate bacterial markers, Prevotella enoeca and Ruthenibacterium lactatiformans, more abundant in BRAF^V600E and BRAF wild-type subjects respectively, emerged as single factors with the best performance in distinguishing BRAF status (AUROC = 0.72 and 0.74, respectively, 95% confidence interval). Furthermore, the combination of the 10 differentially represented microorganisms between the two groups improved performance in discriminating serrated CRC driven by BRAF mutation from BRAF wild-type CRC cases (AUROC = 0.85, 95% confidence interval, 0.69-1.01).

CONCLUSION

Overall, our results suggest that BRAF^V600E mutation itself drives a distinctive gut microbiota signature and provide predictive CRC-associated bacterial biomarkers able to discriminate BRAF status in CRC patients and, thus, useful to devise non-invasive patient-selective diagnostic strategies and patient-tailored optimized therapies.

Role of gut microbiota in epigenetic regulation of colorectal Cancer

Colorectal cancer (CRC) remains one of the most commonly diagnosed cancers and a leading cause of cancer-related deaths worldwide. The stepwise accumulation of epigenetic alterations in the normal colorectal epithelium has been reported to act as a driving force for the initiation and promotion of tumorigenesis in CRC. From a mechanistic standpoint, emerging evidence indicates that within the colorectal epithelium, the diverse gut microbiota can interact with host cells to regulate multiple physiological processes. In fact, recent studies have found that the gut microbiota represents a potential cause of carcinogenesis, invasion, and metastasis via DNA methylation, histone modifications, and non-coding RNAs - providing an epigenetic perspective for the connection between the gut microbiota and CRC. Herein, we comprehensively review the recent research that provides a comprehensive yet succinct evidence connecting the gut microbiota to CRC at an epigenetic level, including carcinogenic mechanisms of cancer-related microbiota, and the potential for utilizing the gut microbiota as CRC biomarkers. These scientific findings highlight a promising future for manipulating the gut microbiota to improve clinical outcomes in patients suffering from CRC.

Serrated lesions of the colon and rectum: Emergent epidemiological data and molecular pathways

In 2010, serrated polyps (SP) of the colon have been included in the WHO classification of digestive tumors. Since then a large corpus of evidence focusing on these lesions are available in the literature. This review aims to analyze the present data on the epidemiological and molecular aspects of SP. Hyperplastic polyps (HPs) are the most common subtype of SP (70–90%), with a minimal or null risk of malignant transformation, contrarily to sessile serrated lesions (SSLs) and traditional serrated adenomas (TSAs), which represent 10–20% and 1% of adenomas, respectively. The malignant transformation, when occurs, is supported by a specific genetic pathway, known as the serrated-neoplasia pathway. The time needed for malignant transformation is not known, but it may occur rapidly in some lesions. Current evidence suggests that a detection rate of SP ≥15% should be expected in a population undergoing screening colonoscopy. There are no differences between primary colonoscopies and those carried out after positive occult fecal blood tests, as this screening test fails to identify SP, which rarely bleed. Genetic similarities between SP and interval cancers suggest that these cancers could arise from missed SP. Hence, the detection rate of serrated-lesions should be evaluated as a quality indicator of colonoscopy. There is a lack of high-quality longitudinal studies analyzing the long-term risk of developing colorectal cancer (CRC), as well as the cancer risk factors and molecular tissue biomarkers. Further studies are needed to define an evidence-based surveillance program after the removal of SP, which is currently suggested based on experts’ opinions.

A comprehensive analysis of the microbiota composition and gene expression in colorectal cancer

BACKGROUND

The dysregulation of gut microbiota is pivotal in colorectal carcinogenesis. Meanwhile, altered gut microbiome may affect the development of intestinal diseases through interaction with the host genes. However, the synergy between the altered gut microbiota composition and differential expression of specific genes in colorectal cancer (CRC) remains elusive. Thus, we integrated the data from 16S rRNA gene sequences and RNA sequences to investigate the potential relationship between genes and gut microbes in patients with CRC.

RESULTS

Compared with normal samples, the presence of Proteobacteria and Fusobacteria increased considerably in CRC samples; conversely, the abundance of Firmicutes and Spirochaetes decreased markedly. In particular, the genera Fusobacterium, Catenibacterium, and Shewanella were only detected in tumor samples. Meanwhile, a closely interaction between Butyricimonas and Clostridium was observed in the microbiome network. Furthermore, a total of 246 (differentially expressed genes) DEGs were identified between tumor and normal tissues. Both DEGs and microbiota were involved in bile secretion and steroid hormone biosynthesis pathways. Finally, genes like cytochrome P450 family 3 subfamily A member 4 (CYP3A4) and ATP binding cassette subfamily G member 2 (ABCG2) enriched in these two pathways were connected with the prognosis of CRC, and CRC patients with low expression level of CYP3A4 and ABCG2 had longer survival time.

CONCLUSION

Identifying the complicated interaction between gut microbiota and the DEGs contributed to further understand the pathogenesis of CRC, and these findings might enable better diagnosis and treatment of CRC patients.

Separating the Empirical Wheat From the Pseudoscientific Chaff: A Critical Review of the Literature Surrounding Glyphosate, Dysbiosis and Wheat-Sensitivity

The prevalence of digestive disorders has increased globally, as countries have adopted a more "Westernized" diet pattern. A Western diet, characterized as high in fat and refined carbohydrates, can also be defined as a product of increased technology and industrialization. Modern farmers rely on agrochemicals to meet the needs of a growing population, and these chemicals have shifted the Western diet's chemical composition. While the number of individuals choosing to live a wheat-free lifestyle without a celiac disease diagnosis has increased, clinical trials have shown that gluten from wheat is not responsible for causing symptoms in healthy individuals suggesting that something else is inducing symptoms. The herbicide, glyphosate, is applied to wheat crops before harvest to encourage ripening resulting in higher glyphosate residues in commercial wheat products within North America. Glyphosate inhibits the shikimate pathway, a pathway exclusive to plants and bacteria. Glyphosate's effect on dysbiosis was not considered when making safety recommendations. Here, we evaluate the literature surrounding glyphosate's effects on the gut microbiome and conclude that glyphosate residues on food could cause dysbiosis, given that opportunistic pathogens are more resistant to glyphosate compared to commensal bacteria. However, research on glyphosate's effects on the microbiome suffers from numerous methodological weaknesses, and these limitations make it impossible to draw any definitive conclusions regarding glyphosate's influence on health through alterations in the gut microbiome. In this review, we critically evaluate the evidence currently known and discuss recommendations for future studies.

Treatment of non-erosive reflux disease and dynamics of the esophageal microbiome: a prospective multicenter study

Non-erosive reflux disease (NERD) pathogenesis has not been thoroughly evaluated. Here, we assessed the response of patients with NERD to proton pump inhibitor (PPI) therapy; changes in the microbiome and biologic marker expression in the esophageal mucosa were also evaluated. Patients with NERD (n = 55) received esomeprazole (20 mg) for eight weeks. The treatment response was evaluated at baseline, week four, and week eight. Esophageal mucosal markers and oropharyngeal and esophageal microbiomes were analyzed in patients who underwent upper gastrointestinal endoscopy at screening (n = 18). Complete and partial response rates at week eight were 60.0% and 32.7% for heartburn, and 61.8% and 29.1% for regurgitation, respectively. The expressions of several inflammatory cytokines, including IL-6, IL-8, and NF-κB, were decreased at week eight. Streptococcus, Haemophilus, Prevotella, Veillonella, Neisseria, and Granulicatella were prevalent regardless of the time-point (baseline vs. week eight) and organ (oropharynx vs. esophagus). The overall composition of oropharyngeal and esophageal microbiomes showed significant difference (P = 0.004), which disappeared after PPI therapy. In conclusion, half-dose PPI therapy for eight weeks could effectively control NERD symptoms. The expression of several inflammatory cytokines was reduced in the esophagus, and oropharyngeal and esophageal microbiomes in patients with NERD showed significant difference. However, the microbial compositions in the oropharynx and esophagus were not affected by PPI therapy in this study. Impact of PPI on the microbiome in patients with NERD should be more investigated in future studies.

Molecular Pathogenesis and Classification of Colorectal Carcinoma

Purpose of review

Molecular pathways in colorectal carcinogenesis involve several complex genetic and epigenetic modulations that cause normal colonic mucosa to metamorphose into a benign polyp and subsequently into a malignant tumor. Our purpose is to recapitulate historical and recent genomic research in order to augment the understanding of colorectal cancer pathogenesis.

Recent Findings

In 2015, the molecular classification for colorectal cancers was unified into one system with four distinct groups, also called as consensus molecular subtypes. This led to an enhanced understanding of molecular and immune signatures which has implications on predicting the clinical behavior as well as response to different therapeutic agents.

Summary

In this review, we expound on the current literature as well as draw on our own experience to present the important molecular pathogenesis pathways, key genetic mutations, differences in pathogenesis of left versus right sided tumors as well as the molecular classification of colorectal cancers.

Risk for Colorectal Neoplasia in Patients With Helicobacter pylori Infection: A Systematic Review and Meta-analysis

Helicobacter pylori may reportedly be associated with extragastric malignancy beyond gastric cancer. The present study aimed to evaluate the association between H. pylori infection and colorectal neoplasia through a systematic review and meta-analysis.

Potential Use of Biotherapeutic Bacteria to Target Colorectal Cancer-Associated Taxa

The role of the gut microbiome in human health and disease is the focus of much attention. It has been widely agreed upon that our gut bacteria play a role in host immunity, nutrient absorption, digestion, metabolism, and other key drivers of health. Furthermore, certain microbial signatures and specific taxa have also been associated with the development of diseases, such as obesity; inflammatory bowel disease; and, indeed, colorectal cancer (CRC), which is the focus of this review. By extension, such taxa represent potential therapeutic targets. In particular, the emerging human pathogen Fusobacterium nucleatum represents an important agent in CRC development and its control within the gastrointestinal tract is desirable. This paper reviews the principal bacterial pathogens that have been associated with CRC to date and discusses the in vitro and human studies that have shown the potential use of biotherapeutic strains as a means of targeting CRC-associated bacteria.

Acetylcholinesterase Inhibitor Pyridostigmine Bromide Attenuates Gut Pathology and Bacterial Dysbiosis in a Murine Model of Ulcerative Colitis

BACKGROUND

Ulcerative colitis (UC) is a Th2 inflammatory bowel disease characterized by increased IL-5 and IL-13 expression, eosinophilic/neutrophilic infiltration, decreased mucus production, impaired epithelial barrier, and bacterial dysbiosis of the colon. Acetylcholine and nicotine stimulate mucus production and suppress Th2 inflammation through nicotinic receptors in lungs but UC is rarely observed in smokers and the mechanism of the protection is unclear.

METHODS

In order to evaluate whether acetylcholine can ameliorate UC-associated pathologies, we employed a mouse model of dextran sodium sulfate (DSS)-induced UC-like conditions, and a group of mice were treated with Pyridostigmine bromide (PB) to increase acetylcholine availability. The effects on colonic tissue morphology, Th2 inflammatory factors, MUC2 mucin, and gut microbiota were analyzed.

RESULTS

DSS challenge damaged the murine colonic architecture, reduced the MUC2 mucin and the tight-junction protein ZO-1. The PB treatment significantly attenuated these DSS-induced responses along with the eosinophilic infiltration and the pro-Th2 inflammatory factors. Moreover, PB inhibited the DSS-induced loss of commensal Clostridia and Flavobacteria, and the gain of pathogenic Erysipelotrichia and Fusobacteria.

CONCLUSIONS

Together, these data suggest that in colons of a murine model, PB promotes MUC2 synthesis, suppresses Th2 inflammation and attenuates bacterial dysbiosis therefore, PB has a therapeutic potential in UC.

Targeting Programmed Fusobacterium nucleatum Fap2 for Colorectal Cancer Therapy

Colorectal patients generally have the maximum counts of Fusobacterium nucleatum (F. nucleatum) in tumors and elevate colorectal adenomas and carcinomas, which show the lowest rate of human survival. Hence, F. nucleatum is a diagnostic marker of colorectal cancer (CRC). Studies demonstrated that targeting fusobacterial Fap2 or polysaccharide of the host epithelium may decrease fusobacteria count in the CRC. Attenuated F. nucleatum-Fap2 prevents transmembrane signals and inhibits tumorigenesis inducing mechanisms. Hence, in this review, we hypothesized that application of genetically programmed fusobacterium can be skillful and thus reduce fusobacterium in the CRC. Genetically programmed F. nucleatum is a promising antitumor strategy.

Fusobacterium nucleatum, the communication with colorectal cancer

Colorectal cancer (CRC) is the fourth most common cancer in 2018 with poor prognosis. Fusobacterium nucleatum (F.n), an anaerobe, is found to be enriched in both stools and tumor tissues of CRC patients. As surveys show, tumor initiates before the collection of F.n. In return, F.n helps cancer cells to build up tumor microenvironment and benefit for their chemo-resistant. The elements constituted the tumor environment, including neutrophils, macrophages and lymphocytes, contribute to the existing of tumor cells respectively. However, the integrated and interactive roles of those elements are poorly investigated. The intracellular molecular alteration MSI is a result of F.n infection and the microbiology-molecular pathological epidemiology (MPE) has become a new trend to analysis F.n and tumorigenesis. Chemoresistance of tumor cells is also affected by F.n induced microenvironment, or F.n achieves it directly. Finally, F.n could be a biomarker of CRC. All in all, our review will lay a foundation for the therapy of CRC through the interference of F.n and perspective to follow-up studies.

The Molecular Hallmarks of the Serrated Pathway in Colorectal Cancer

Colorectal cancer (CRC) is a leading cause of cancer death worldwide. It includes different subtypes that differ in their clinical and prognostic features. In the past decade, in addition to the conventional adenoma-carcinoma model, an alternative multistep mechanism of carcinogenesis, namely the “serrated pathway”, has been described. Approximately, 15 to 30% of all CRCs arise from neoplastic serrated polyps, a heterogeneous group of lesions that are histologically classified into three morphologic categories: hyperplastic polyps, sessile serrated adenomas/polyps, and the traditional serrated adenomas/polyps. Serrated polyps are characterized by genetic (BRAF or KRAS mutations) and epigenetic (CpG island methylator phenotype (CIMP)) alterations that cooperate to initiate and drive malignant transformation from normal colon mucosa to polyps, and then to CRC. The high heterogeneity of the serrated lesions renders their diagnostic and pathological interpretation difficult. Hence, novel genetic and epigenetic biomarkers are required for better classification and management of CRCs. To date, several molecular alterations have been associated with the serrated polyp-CRC sequence. In addition, the gut microbiota is emerging as a contributor to/modulator of the serrated pathway. This review summarizes the state of the art of the genetic, epigenetic and microbiota signatures associated with serrated CRCs, together with their clinical implications.

Oral microbiota and gastrointestinal cancer

The microbiota inhabiting the oral cavity is a complex ecosystem and responsible for resisting pathogens, maintaining homeostasis, and modulating the immune system. Some components of the oral microbiota contribute to the etiology of some oral diseases. Accumulating evidence suggests that the human oral microbiota is implicated in the development and progression of gastrointestinal cancer. In this review, we described the current understanding of possible roles and mechanisms of oral microbiota in the gastrointestinal cancers studied to date. The perspectives for oral microbiota as the biomarkers for early detection and new therapeutic targets were also discussed.

The presence of bacteria varies between colorectal adenocarcinomas, precursor lesions and non-malignant tissue

BACKGROUND

A causal association has been suggested between certain bacteria and colorectal cancer (CRC). Only a few studies have, however, investigated the presence of these bacteria directly in colon tissue with conflicting results. It is thus uncertain which role they may have in prognosis and carcinogenesis of CRC.

METHODS

Formalin-fixed and paraffin-embedded (FFPE) colorectal tissue samples from patients diagnosed with colorectal cancer (CRC)(tumor and paired normal tissue, n = 99), adenomas (n = 96), or diverticular disease (n = 104) were tested for the presence and bacterial load of Streptococcus gallolyticus (S. gallolyticus), Fusobacterium nucleatum (F. nucleatum), and Bacteroides fragilis (B. fragilis) using quantitative PCR. A subsequent broader search was conducted on a subset of samples using 16S ribosomal RNA gene sequencing. Finally, to evaluate the prognostic value, the bacterial status was compared to patient outcome.

RESULTS

S. gallolyticus was not detected by qPCR in any of the investigated tissue samples and F. nucleatum and B. fragilis were found to be equally distributed in tumors, paired normal tissue, and diverticula, but significantly less present in adenomas compared to both tumors and diverticula. Neither, F. nucleatum nor B. fragilis status affected the five-year prognosis of the patients. The 16S rRNA gene sequencing data revealed that tumors were associated with the Prevotella genus while conversely adenomas and diverticula were associated with Acinetobacter genus.

CONCLUSION

These findings do not support a role of F. nucleatum or B. fragilis during colorectal beginning, while S. gallolyticus was not implicated in the colorectal tissue of a Danish population. A potential role of the bacterial genera Prevotella and Acinetobacter was indicated, and requires further investigations.

Bugs, drugs, and cancer: can the microbiome be a potential therapeutic target for cancer management?

Outnumbering our own cells over ten times, gut microbes can even be considered an additional organ. Several studies have explored the association between microbiomes and antitumor drug response. It has been reported that the presence of specific bacteria might modulate cancer progression and the efficacy of anticancer therapeutics. Bacteria-targeting intervention can provide crucial guidance for the design of next-generation antitumor drugs. Here, we review previous findings elucidating the impact of gut microbiomes on cancer treatment and the possible underlying mechanisms. In addition, we examine the role of microbiome manipulation in controlling tumor growth. Finally, we discuss concerns regarding the alteration of the microbiome composition, and the potential approaches to surpass existing limitations.

Insights into Pathogenic Interactions Among Environment, Host, and Tumor at the Crossroads of Molecular Pathology and Epidemiology

Evidence indicates that diet, nutrition, lifestyle, the environment, the microbiome, and other exogenous factors have pathogenic roles and also influence the genome, epigenome, transcriptome, proteome, and metabolome of tumor and nonneoplastic cells, including immune cells. With the need for big-data research, pathology must transform to integrate data science fields, including epidemiology, biostatistics, and bioinformatics. The research framework of molecular pathological epidemiology (MPE) demonstrates the strengths of such an interdisciplinary integration, having been used to study breast, lung, prostate, and colorectal cancers. The MPE research paradigm not only can provide novel insights into interactions among environment, tumor, and host but also opens new research frontiers. New developments-such as computational digital pathology, systems biology, artificial intelligence, and in vivo pathology technologies-will further transform pathology and MPE. Although it is necessary to address the rarity of transdisciplinary education and training programs, MPE provides an exemplary model of integrative scientific approaches and contributes to advancements in precision medicine, therapy, and prevention.

Diets That Promote Colon Inflammation Associate With Risk of Colorectal Carcinomas That Contain Fusobacterium nucleatum

BACKGROUND & AIMS

Specific nutritional components are likely to induce intestinal inflammation, which is characterized by increased levels of interleukin 6 (IL6), C-reactive protein (CRP), and tumor necrosis factor-receptor superfamily member 1B (TNFRSF1B) in the circulation and promotes colorectal carcinogenesis. The inflammatory effects of a diet can be estimated based on an empiric dietary inflammatory pattern (EDIP) score, calculated based on intake of 18 foods associated with plasma levels of IL6, CRP, and TNFRSF1B. An inflammatory environment in the colon (based on increased levels of IL6, CRP, and TNFRSF1B in peripheral blood) contributes to impairment of the mucosal barrier and altered immune cell responses, affecting the composition of the intestinal microbiota. Colonization by Fusobacterium nucleatum has been associated with the presence and features of colorectal adenocarcinoma. We investigated the association between diets that promote inflammation (based on EDIP score) and colorectal cancer subtypes classified by level of F nucleatum in the tumor microenvironment.

METHODS

We calculated EDIP scores based on answers to food frequency questionnaires collected from participants in the Nurses' Health Study (through June 1, 2012) and the Health Professionals Follow-up Study (through January 31, 2012). Participants in both cohorts reported diagnoses of rectal or colon cancer in biennial questionnaires; deaths from unreported colorectal cancer cases were identified through the National Death Index and next of kin. Colorectal tumor tissues were collected from hospitals where the patients underwent tumor resection and F nucleatum DNA was quantified by a polymerase chain reaction assay. We used multivariable duplication-method Cox proportional hazard regression to assess the associations of EDIP scores with risks of colorectal cancer subclassified by F nucleatum status.

RESULTS

During 28 years of follow-up evaluation of 124,433 participants, we documented 951 incident cases of colorectal carcinoma with tissue F nucleatum data. Higher EDIP scores were associated with increased risk of F nucleatum-positive colorectal tumors (P_trend = .03); for subjects in the highest vs lowest EDIP score tertiles, the hazard ratio for F nucleatum-positive colorectal tumors was 1.63 (95% CI, 1.03-2.58). EDIP scores did not associate with F nucleatum-negative tumors (P_trend = .44). High EDIP scores associated with proximal F nucleatum-positive colorectal tumors but not with proximal F nucleatum-negative colorectal tumors (P_{heterogeneity} = .003).

CONCLUSIONS

Diets that may promote intestinal inflammation, based on EDIP score, are associated with increased risk of F nucleatum-positive colorectal carcinomas, but not carcinomas that do not contain these bacteria. These findings indicate that diet-induced intestinal inflammation alters the gut microbiome to contribute to colorectal carcinogenesis; nutritional interventions might be used in precision medicine and cancer prevention.

Fusobacterium nucleatum in Colorectal Cancer Relates to Immune Response Differentially by Tumor Microsatellite Instability Status

The presence of Fusobacterium nucleatum (F. nucleatum) in colorectal carcinoma tissue has been associated with microsatellite instability (MSI), lower-level T-cell infiltrates, and poor clinical outcomes. Considering differences in the tumor-immune microenvironment between MSI-high and non-MSI-high carcinomas, we hypothesized that the association of F. nucleatum with immune response might differ by tumor MSI status. Using samples from 1,041 rectal and colon cancer patients within the Nurses' Health Study and Health Professionals Follow-up Study, we measured F. nucleatum DNA in tumor tissue by a quantitative polymerase chain reaction assay. Multivariable logistic regression models were used to examine the association between F. nucleatum status and histopathologic lymphocytic reactions or density of CD3⁺ cells, CD8⁺ cells, CD45RO (PTPRC)⁺ cells, or FOXP3⁺ cells in strata of tumor MSI status. We adjusted for potential confounders, including CpG island methylator phenotype; LINE-1 methylation; and KRAS, BRAF, and PIK3CA mutations. The association of F. nucleatum with tumor-infiltrating lymphocytes (TIL) and intratumoral periglandular reaction differed by tumor MSI status (P _interaction = 0.002). The presence of F. nucleatum was negatively associated with TIL in MSI-high tumors [multivariable odds ratio (OR), 0.45; 95% confidence interval (CI), 0.22-0.92], but positively associated with TIL in non-MSI-high tumors (multivariable OR 1.91; 95% CI, 1.12-3.25). No significant differential association was observed for peritumoral lymphocytic reaction, Crohn-like lymphoid reaction, or T-cell densities. In conclusion, the association of F. nucleatum with immune response to colorectal carcinoma differs by tumor MSI status, suggesting that F. nucleatum and MSI status interact to affect antitumor immune reactions. Cancer Immunol Res; 6(11); 1327-36. ©2018 AACR See related Spotlight on p. 1290.

Nutraceuticals in colorectal cancer: A mechanistic approach

Colorectal cancer (CRC) is one of the most diagnosed cancers in the world. Even though screening, surgery and oncology have greatly advanced, CRC is still one of the leading causes of cancer deaths, with 700,000 annual mortalities in both men and women. Environmental and lifestyle factors brought up by industrialization, such as an altered diet, lack of physical activity, increase in alcohol consumption, and circadian disruption, have greatly affected the burden of CRC. These factors increase the CRC risk, at least partly, by pathologically altering the colonic environment, including composition of the gut microbiota, referred to as dysbiosis. Colonic dysbiosis can promote pro-carcinogenic immune signaling cascades, leading to pro-tumorigenic inflammation, carcinogen production, and altered cellular responses in susceptible host resulting to development and/or progression of CRC. Nutraceuticals such as prebiotic molecules and probiotic bacterial species can help maintain intestinal microbial homeostasis and thus mitigate this pathological processes. Therefore, prebiotics and probiotics can hinder the effects of dysbiosis by encouraging anti-carcinogenic, anti-inflammatory immunity, the maintenance of the intestinal epithelial barrier, pro-apoptotic mechanisms, and carcinogen inactivation. In addition to its implications in preventing CRC, because of the mechanisms affected, nutraceuticals are being discovered as potential adjuncts to immune checkpoint inhibitors in the treatment of CRC. In this review, we provide an overview of the potential implications of prebiotics and probiotics in the prevention and treatment of CRC.

Intestinal microbiota: a novel perspective in colorectal cancer biotherapeutics

It is believed that genetic factors, immune system dysfunction, chronic inflammation, and intestinal microbiota (IM) dysbiosis contribute to the pathogenesis of colorectal cancer (CRC). The beneficial role played by the direct regulation of IM in inflammatory bowel disease treatment is identified by the decreased growth of harmful bacteria and the increased production of anti-inflammatory factors. Interestingly, gut microbiota has been proven to inhibit tumor formation and progression in inflammation/carcinogen-induced CRC mouse models. Recently, evidence has indicated that IM is involved in the negative regulation of tumor immune response in tumor microenvironment, which then abolishes or accelerates anticancer immunotherapy in several tumor animals. In clinical trials, a benefit of IM-based CRC therapies in improving the intestinal immunity balance, epithelial barrier function, and quality of life has been reported. Meanwhile, specific microbiota signature can modulate host's sensitivity to chemo-/radiotherapy and the prognosis of CRC patients. In this review, we aim to 1) summarize the potential methods of IM-based therapeutics according to the recent results; 2) explore its roles and underlying mechanisms in combination with other therapies, especially in biotherapeutics; 3) discuss its safety, deficiency, and future perspectives.

Intestinal microbiota, chronic inflammation, and colorectal cancer

In addition to genetic and epigenetic factors, various environmental factors, including diet, play important roles in the development of colorectal cancer (CRC). Recently, there is increasing interest in the intestinal microbiota as an environmental risk factor for CRC, because diet also influences the composition of the intestinal microbiota. The human intestinal microbiota comprises about 100 trillion microbes. This microbiome thrives on undigested dietary residues in the intestinal lumen and produces various metabolites. It is well known that the dietary risk factors for CRC are mediated by dysbiosis of the intestinal microbiota and their metabolites. In this review, we describe the bacterial taxa associated with CRC, including Fusobacterium nucleatum, enterotoxigenic Bacteroides fragilis, Escherichia coli, and butyrate-producing bacteria. We also discuss the host-diet interaction in colorectal carcinogenesis.

Integrative analysis of exogenous, endogenous, tumour and immune factors for precision medicine

Immunotherapy strategies targeting immune checkpoints such as the CTLA4 and CD274 (programmed cell death 1 ligand 1, PD-L1)/PDCD1 (programmed cell death 1, PD-1) T-cell coreceptor pathways are revolutionising oncology. The approval of pembrolizumab use for solid tumours with high-level microsatellite instability or mismatch repair deficiency by the US Food and Drug Administration highlights promise of precision immuno-oncology. However, despite evidence indicating influences of exogenous and endogenous factors such as diet, nutrients, alcohol, smoking, obesity, lifestyle, environmental exposures and microbiome on tumour-immune interactions, integrative analyses of those factors and immunity lag behind. Immune cell analyses in the tumour microenvironment have not adequately been integrated into large-scale studies. Addressing this gap, the transdisciplinary field of molecular pathological epidemiology (MPE) offers research frameworks to integrate tumour immunology into population health sciences, and link the exposures and germline genetics (eg, HLA genotypes) to tumour and immune characteristics. Multilevel research using bioinformatics, in vivo pathology and omics (genomics, epigenomics, transcriptomics, proteomics and metabolomics) technologies is possible with use of tissue, peripheral blood circulating cells, cell-free plasma, stool, sputum, urine and other body fluids. This immunology-MPE model can synergise with experimental immunology, microbiology and systems biology. GI neoplasms represent exemplary diseases for the immunology-MPE model, given rich microbiota and immune tissues of intestines, and the well-established carcinogenic role of intestinal inflammation. Proof-of-principle studies on colorectal cancer provided insights into immunomodulating effects of aspirin, vitamin D, inflammatory diets and omega-3 polyunsaturated fatty acids. The integrated immunology-MPE model can contribute to better understanding of environment-tumour-immune interactions, and effective immunoprevention and immunotherapy strategies for precision medicine.

Gut microbiome of Moroccan colorectal cancer patients

Although colorectal cancer is the third leading cause of death in Morocco, there are no studies of the microbiome changes associated with the disease in the Moroccan population. The aim of our study was to compare the stool microbiome of Moroccan cancer patients with healthy individuals. We analyzed the microbiome composition of samples from 11 CRC patients and 12 healthy individuals by 16S rRNA amplicon sequencing. Principal coordinate analysis of samples revealed defined cancer versus healthy clusters. Our findings showed that cancer samples had higher proportions of Firmicutes (T = 50.5%; N = 28.4%; p = 0.04), specifically of Clostridia (T = 48.3%; N = 19.0%; p = 0.002), and Fusobacteria (T = 0.1%; N = 0.0%; p = 0.02), especially of Fusobacteriia (T = 0.1%; N = 0.0%; p = 0.02), while Bacteroidetes were enriched in healthy samples (T = 35.1%; N = 62.8%; p = 0.06), particularly the class Bacteroidia (T = 35.1%; N = 62.6%; p = 0.06). Porphyromonas, Clostridium, Ruminococcus, Selenomonas, and Fusobacterium were significantly overrepresented in diseased patients, similarly to other studies. Predicted functional information showed that bacterial motility proteins, flagellar assembly, and fatty acid biosynthesis metabolism were significantly overrepresented in cancer patients, while amino acid metabolism and glycan biosynthesis were overrepresented in controls. This suggests that involvement of these functional metagenomes is similar and relevant in the carcinogenesis process, independent of the origin of the samples. Results from this study allowed identification of bacterial taxa relevant to the Moroccan population and encourages larger studies to facilitate population-directed therapeutic approaches.

Association between Fusobacterium nucleatum and colorectal cancer: Progress and future directions

The initiation and progression of colorectal cancer (CRC) involves genetic and epigenetic alterations influenced by dietary and environmental factors. Increasing evidence has linked the intestinal microbiota and colorectal cancer. More recently, Fusobacterium nucleatum (Fn), an opportunistic commensal anaerobe in the oral cavity, has been associated with CRC. Several research teams have reported an overabundance of Fn in human CRC and have elucidated the possible mechanisms by which Fn is involved in colorectal carcinogenesis in vitro and in mouse models. However, the mechanisms by which Fn promotes colorectal carcinogenesis remain unclear. To provide new perspectives for early diagnosis, the identification of high risk populations and treatment for colorectal cancer, this review will summarize the relative research progresses regarding the relationship between Fn and colorectal cancer.

Fusobacterium's link to colorectal neoplasia sequenced: A systematic review and future insights

AIM

To critically evaluate previous scientific evidence on Fusobacterium's role in colorectal neoplasia development.

METHODS

Two independent investigators systematically reviewed all original scientific articles published between January, 2000, and July, 2017, using PubMed, EMBASE, and MEDLINE. A total of 355 articles were screened at the abstract level. Of these, only original scientific human, animal, and in vitro studies investigating Fusobacterium and its relationship with colorectal cancer (CRC) were included in the analysis. Abstracts, review articles, studies investigating other colonic diseases, and studies written in other languages than English were excluded from our analysis. Ninety articles were included after removing duplicates, resolving disagreements between the two reviewers, and applying the above criteria.

RESULTS

Studies have consistently identified positive associations between Fusobacterium, especially Fusobacterium nucleatum (F. nucleatum), and CRC. Stronger associations were seen in CRCs proximal to the splenic flexure and CpG island methylator phenotype (CIMP)-high CRCs. There was evidence of temporality and a biological gradient, with increased F. nucleatum DNA detection and quantity along the traditional adenoma-carcinoma sequence and in CIMP-high CRC precursors. Diet may have a differential impact on colonic F. nucleatum enrichment; evidence suggests that high fiber diet may reduce the risk of a subset of CRCs that are F. nucleatum DNA-positive. Data also suggest shorter CRC and disease-specific survival with increased amount of F. nucleatum DNA in CRC tissue. The pathophysiology of enrichment of F. nucleatum and other Fusobacterium species in colonic tissue is unclear; however, the virulence factors and changes to the local colonic environment with disruption of the protective mucus layer may contribute. The presence of a host lectin (Gal-GalNAc) in the colonic epithelium may also mediate F. nucleatum attachment to CRC and precursors through interaction with an F. nucleatum protein, fibroblast activation protein 2 (FAP2). The clinical significance of detection or enrichment of Fusobacterium in colorectal neoplasia is ambiguous, but data suggest a procarcinogenic effect of F. nucleatum, likely due to activation of oncogenic and inflammatory pathways and modulation of the tumor immune environment. This is hypothesized to be mediated by certain F. nucleatum strains carrying invasive properties and virulence factors such as FadA and FAP.

CONCLUSION

Evidence suggests a potential active role of Fusobacterium, specifically F. nucleatum, in CRC. Future prospective and experimental human studies would fill an important gap in this literature.

Microbial Interactions and Interventions in Colorectal Cancer

Recently, several lines of evidence that indicate a strong link between the development of colorectal cancer (CRC) and aspects of the gut microbiota have become apparent. However, it remains unclear how changes in the gut microbiota might influence carcinogenesis or how regional organization of the gut might influence the microbiota. In this review, we discuss several leading theories that connect gut microbial dysbiosis with CRC and set this against a backdrop of what is known about proximal-distal gut physiology and the pathways of CRC development and progression. Finally, we discuss the potential for gut microbial modulation therapies, for example, probiotics, antibiotics, and others, to target and improve gut microbial dysbiosis as a strategy for the prevention or treatment of CRC.

What influences preneoplastic colorectal lesion recurrence?

The hypothesis of the local recurrence of preneoplastic lesions was first put forward in the 1950s. Disease recurrence may result from an inherent imbalance in cell proliferation that promotes carcinogenesis in apparently normal mucosa. Our review sheds light on how early preneoplastic lesions could be used to diagnose relapsed preneoplastic and, developing neoplastic lesions. We focus in detail on the clinical-pathological and molecular features of adenoma subtypes and their role in relapsed adenoma and their development into colorectal carcinoma. Moreover, we include the data available on microbiota and its metabolites and their role in recurrence. We strongly believe that a significant improvement could be achieved in colorectal screening by introducing personalized endoscopic surveillance for polyp-bearing patients on the basis of the presence of molecular markers that are predictive of recurrence.