Do biofilms confer a pro-carcinogenic state?

Escherichia coli on colorectal cancer: A two-edged sword

Escherichia coli (E. coli) is a ubiquitous symbiotic bacterium in the gut, and the diversity of E. coli genes determines the diversity of its functions. In this review, the two-edged sword theory was innovatively proposed. For the question 'how can we harness the ambivalent nature of E. coli to screen and treat CRC?', in terms of CRC screening, the variations in the abundance and subtypes of E. coli across different populations present an opportunity to utilise it as a biomarker, while in terms of CRC treatment, the natural beneficial effect of E. coli on CRC may be limited, and engineered E. coli, particularly certain subtypes with probiotic potential, can indeed play a significant role in CRC treatment. It seems that the favourable role of E. coli as a genetic tool lies not in its direct impact on CRC but its potential as a research platform that can be integrated with various technologies such as nanoparticles, imaging methods, and synthetic biology modification. The relationship between gut microflora and CRC remains unclear due to the complex diversity and interaction of gut microflora. Therefore, the application of E. coli should be based on the 'One Health' view and take the interactions between E. coli and other microorganisms, host, and environmental factors, as well as its own changes into account. In this paper, the two-edged sword role of E. coli in CRC is emphasised to realise the great potential of E. coli in CRC screening and treatment.

Suppression of colon cancer growth by berberine mediated by the intestinal microbiota and the suppression of DNA methyltransferases (DNMTs)

The purpose of this study was to demonstrate the regulatory effect of berberine (BBR) on the intestinal microbiota and related epigenetics during the inhibition of colon cancer cell growth in vitro and in vivo. We used a nude mouse xenograft model with HT29 colon cancer cells to establish and divide into a model group and BBR group. The mice were treated for four weeks, and HT29 cells in the BBR group were cultured for 48 h. Cetuximab and the DNA transmethylase (DNMT) inhibitor 5-AZA-dC were added to HT29 cells. Tumour volume and weight were measured by hematoxylin-eosin (HE) staining for histopathological observation. Mouse faeces were collected, and the gut microbiota was analysed with 16S rDNA amplicons. The levels of cytokines in the supernatant of HT29 cells were measured by ELISA. A CCK-8 kit was used to examine the proliferation of HT29 cells, and RT‒PCR was used to measure the levels of c-Myc, DNMT1, DNMT3A, and DNMT3B. We found that BBR reduced the growth of colon cancer cells to a certain extent in vitro and in vivo, although the difference was not statistically significant compared with that in the model group. BBR significantly mediated the abundance, composition and metabolic functions of the intestinal microbial flora in mice with colon cancer. The effect of BBR on inflammatory cytokines, including IL-6, FGF, and PDGF, was not obvious, but BBR significantly downregulated IL-10 levels (P < 0.05) and reduced c-Myc, DNMT1, and DNMT3B levels (P < 0.05). Inhibiting DNMTs with 5-AZA-dC significantly suppressed the proliferation of HT29 cells, which was consistent with the effect of BBR. The inhibitory effect of berberine on colon cancer is related not only to the intestinal microbiota and its metabolic functions but also to the regulation of DNMTs.

Contribution of pks+ Escherichia coli (E. coli) to Colon Carcinogenesis

Colorectal cancer (CRC) stands as a significant global health concern, ranking second in mortality and third in frequency among cancers worldwide. While only a small fraction of CRC cases can be attributed to inherited genetic mutations, the majority arise sporadically due to somatic mutations. Emerging evidence reveals gut microbiota dysbiosis to be a contributing factor, wherein polyketide synthase-positive Escherichia coli (pks+ E. coli) plays a pivotal role in CRC pathogenesis. pks+ bacteria produce colibactin, a genotoxic protein that causes deleterious effects on DNA within host colonocytes. In this review, we examine the role of the gut microbiota in colon carcinogenesis, elucidating how colibactin-producer bacteria induce DNA damage, promote genomic instability, disrupt the gut epithelial barrier, induce mucosal inflammation, modulate host immune responses, and influence cell cycle dynamics. Collectively, these actions foster a microenvironment conducive to tumor initiation and progression. Understanding the mechanisms underlying pks+ bacteria-mediated CRC development may pave the way for mass screening, early detection of tumors, and therapeutic strategies such as microbiota modulation, bacteria-targeted therapy, checkpoint inhibition of colibactin production and immunomodulatory pathways.

Gut microbiome-metabolites axis: A friend or foe to colorectal cancer progression

An expanding corpus of research robustly substantiates the complex interrelation between gut microbiota and the onset, progression, and metastasis of colorectal cancer. Investigations in both animal models and human subjects have consistently underscored the role of gut bacteria in a variety of metabolic activities, driven by dietary intake. These activities include amino acid metabolism, carbohydrate fermentation, and the generation and regulation of bile acids. These metabolic derivatives, in turn, have been identified as significant contributors to the progression of colorectal cancer. This thorough review meticulously explores the dynamic interaction between gut bacteria and metabolites derived from the breakdown of amino acids, fatty acid metabolism, and bile acid synthesis. Notably, bile acids have been recognized for their potential carcinogenic properties, which may expedite tumor development. Extensive research has revealed a reciprocal influence of gut microbiota on the intricate spectrum of colorectal cancer pathologies. Furthermore, strategies to modulate gut microbiota, such as dietary modifications or probiotic supplementation, may offer promising avenues for both the prevention and adjunctive treatment of colorectal cancer. Nevertheless, additional research is imperative to corroborate these findings and enhance our comprehension of the underlying mechanisms in colorectal cancer development.

Emerging strategies for combating Fusobacterium nucleatum in colorectal cancer treatment: Systematic review, improvements and future challenges

Colorectal cancer (CRC) is generally characterized by a high prevalence of Fusobacterium nucleatum (F. nucleatum), a spindle-shaped, Gram-negative anaerobe pathogen derived from the oral cavity. This tumor-resident microorganism has been closely correlated with the occurrence, progression, chemoresistance and immunosuppressive microenvironment of CRC. Furthermore, F. nucleatum can specifically colonize CRC tissues through adhesion on its surface, forming biofilms that are highly resistant to commonly used antibiotics. Accordingly, it is crucial to develop efficacious non-antibiotic approaches to eradicate F. nucleatum and its biofilms for CRC treatment. In recent years, various antimicrobial strategies, such as natural extracts, inorganic chemicals, organic chemicals, polymers, inorganic-organic hybrid materials, bacteriophages, probiotics, and vaccines, have been proposed to combat F. nucleatum and F. nucleatum biofilms. This review summarizes the latest advancements in anti-F. nucleatum research, elucidates the antimicrobial mechanisms employed by these systems, and discusses the benefits and drawbacks of each antimicrobial technology. Additionally, this review also provides an outlook on the antimicrobial specificity, potential clinical implications, challenges, and future improvements of these antimicrobial strategies in the treatment of CRC.

Association between gut microbiota and CpG island methylator phenotype in colorectal cancer

The intestinal microbiota is an important environmental factor implicated in CRC development. Intriguingly, modulation of DNA methylation by gut microbiota has been reported in preclinical models, although the relationship between tumor-infiltrating bacteria and CIMP status is currently unexplored. In this study, we investigated tumor-associated bacteria in 203 CRC tumor cases and validated the findings using The Cancer Genome Atlas datasets. We assessed the abundance of Bacteroides fragilis, Escherichia coli, Fusobacterium nucleatum, and Klebsiella pneumoniae through qPCR analysis and observed enrichment of all four bacterial species in CRC samples. Notably, except for E. coli, all exhibited significant enrichment in cases of CIMP. This enrichment was primarily driven by a subset of cases distinguished by high levels of these bacteria, which we labeled as "Superhigh". The bacterial Superhigh status showed a significant association with CIMP (odds ratio 3.1, p-value = 0.013) and with MLH1 methylation (odds ratio 4.2, p-value = 0.0025). In TCGA CRC cases (393 tumor and 45 adj. normal), bacterial taxa information was extracted from non-human whole exome sequencing reads, and the bacterial Superhigh status was similarly associated with CIMP (odds ratio 2.9, p < 0.001) and MLH1 methylation (odds ratio 3.5, p < 0.001). Finally, 16S ribosomal RNA gene sequencing revealed high enrichment of Bergeyella spp. C. concisus, and F. canifelinum in CIMP-Positive tumor cases. Our findings highlight that specific bacterial taxa may influence DNA methylation, particularly in CpG islands, and contribute to the development and progression of CIMP in colorectal cancer.

Parvimonas micra, an oral pathobiont associated with colorectal cancer, epigenetically reprograms human colonocytes

Recently, an intestinal dysbiotic microbiota with enrichment in oral cavity bacteria has been described in colorectal cancer (CRC) patients. Here, we characterize and investigate one of these oral pathobionts, the Gram-positive anaerobic coccus Parvimonas micra. We identified two phylotypes (A and B) exhibiting different phenotypes and adhesion capabilities. We observed a strong association of phylotype A with CRC, with its higher abundance in feces and in tumoral tissue compared with the normal homologous colonic mucosa, which was associated with a distinct methylation status of patients. By developing an in vitro hypoxic co-culture system of human primary colonic cells with anaerobic bacteria, we show that P. micra phylotype A alters the DNA methylation profile promoters of key tumor-suppressor genes, oncogenes, and genes involved in epithelial-mesenchymal transition. In colonic mucosa of CRC patients carrying P. micra phylotype A, we found similar DNA methylation alterations, together with significant enrichment of differentially expressed genes in pathways involved in inflammation, cell adhesion, and regulation of actin cytoskeleton, providing evidence of P. micra's possible role in the carcinogenic process.

Diet-mediated gut microbial community modulation and signature metabolites as potential biomarkers for early diagnosis, prognosis, prevention and stage-specific treatment of colorectal cancer

BACKGROUND

Over the last decade, studies have shown an increased incidence of colorectal cancer (CRC), particularly early onset colorectal cancer (EOCRC). Researchers have demonstrated that dietary behavior, especially among young adults, influences alterations in the gut microbial community, leading to an increased accumulation of pathogenic gut microbiota and a decrease in beneficial ones. Unfortunately, CRC is likely to be diagnosed at a late stage, increasing CRC-related mortality. However, this alteration in the gut microbiota (gut dysbiosis) can be harnessed as a biomarker for non-invasive diagnosis, prognosis, prevention, and treatment of CRC in an effort to prevent late diagnosis and poor prognosis associated with CRC.

AIM OF REVIEW

This review discusses identification of potential biomarkers by targeting diet-mediated gut dysbiosis for the stage-specific diagnosis, prognosis, treatment, and prevention of CRC. Our findings provide a comprehensive insight into the potential of protumorigenic bacteria (e.g.pathogenic Escherichia coli,enterotoxigenic Bacteroides fragilis and Fusobacterium nucleatum) and their metabolites (e.g., colibactin and B. fragilis toxin) from gut dysbiosis as biomarkers for the diagnosis of CRC.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Collectively, a detailed understanding of the available data from current studies suggests that, further research on quantification of metabolites and stage-specific pathogenic microbial abundance is required for the diagnosis and treatment of CRC based on microbial dysbiosis. Specifically, future studies on faecal samples, from patient with CRC, should be conducted for F. nucleatum among different opportunistic bacteria, given its repeated occurrence in faecal samples and CRC biopsies in numerous studies. Finally, we discuss the potential of faecal microbial transplantation (FMT) as an intervention to restore damaged gut microbiota during CRC treatment and management.

Biofilm and Cancer: Interactions and Future Directions for Cancer Therapy

There is a growing body of evidence supporting the significant role of bacterial biofilms in the pathogenesis of various human diseases, including cancer. Biofilms are polymicrobial communities enclosed within an extracellular matrix composed of polysaccharides, proteins, extracellular DNA, and lipids. This complex matrix provides protection against antibiotics and host immune responses, enabling the microorganisms to establish persistent infections. Moreover, biofilms induce anti-inflammatory responses and metabolic changes in the host, further facilitating their survival. Many of these changes are comparable to those observed in cancer cells. This review will cover recent research on the role of bacterial biofilms in carcinogenesis, especially in colorectal (CRC) and gastric cancers, emphasizing the shared physical and chemical characteristics of biofilms and cancer. This review will also discuss the interactions between bacteria and the tumor microenvironment, which can facilitate oncogene expression and cancer progression. This information will provide insight into developing new therapies to identify and treat biofilm-associated cancers, such as utilizing bacteria as delivery vectors, using bacteria to upregulate immune function, or more selectively targeting biofilms and cancer for their shared traits.

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.

Crosstalk between microbial biofilms in the gastrointestinal tract and chronic mucosa diseases

The gastrointestinal (GI) tract is the largest reservoir of microbiota in the human body; however, it is still challenging to estimate the distribution and life patterns of microbes. Biofilm, as the predominant form in the microbial ecosystem, serves ideally to connect intestinal flora, molecules, and host mucosa cells. It gives bacteria the capacity to inhabit ecological niches, communicate with host cells, and withstand environmental stresses. This study intends to evaluate the connection between GI tract biofilms and chronic mucosa diseases such as chronic gastritis, inflammatory bowel disease, and colorectal cancer. In each disease, we summarize the representative biofilm makers including Helicobacter pylori, adherent-invasive Escherichia coli, Bacteroides fragilis, and Fusobacterium nucleatum. We address biofilm's role in causing inflammation and the pro-carcinogenic stage in addition to discussing the typical resistance, persistence, and recurrence mechanisms seen in vitro. Biofilms may serve as a new biomarker for endoscopic and pathologic detection of gastrointestinal disease and suppression, which may be a useful addition to the present therapy strategy.

One-Carbon and Polyamine Metabolism as Cancer Therapy Targets

Cancer metabolic reprogramming is essential for maintaining cancer cell survival and rapid replication. A common target of this metabolic reprogramming is one-carbon metabolism which is notable for its function in DNA synthesis, protein and DNA methylation, and antioxidant production. Polyamines are a key output of one-carbon metabolism with widespread effects on gene expression and signaling. As a result of these functions, one-carbon and polyamine metabolism have recently drawn a lot of interest for their part in cancer malignancy. Therapeutic inhibitors that target one-carbon and polyamine metabolism have thus been trialed as anticancer medications. The significance and future possibilities of one-carbon and polyamine metabolism as a target in cancer therapy are discussed in this review.

The Microbiome in Gastrointestinal Cancers

The human microbiome has been recognized as increasingly important to health and disease. This is especially prescient in the development of various cancers, their progression, and the microbiome's modulation of various anticancer therapeutics. Mechanisms behind these interactions have been increasingly well described through modulation of the host immune system as well as induction of genetic changes and local inactivation of cancer therapeutics. Here, we review these associations for a variety of gastrointestinal malignancies as well as contemporary strategies proposed to leverage these associations to improve cancer treatment outcomes.

Interaction of Gut Microbiota with Endocrine Homeostasis and Thyroid Cancer

The gut microbiota plays a crucial role in healthy individuals as well as in patients with thyroid diseases, including thyroid cancer. Although the prognosis of differentiated thyroid cancer is predictable, that of some poorly differentiated, medullary, and anaplastic thyroid cancers remains unpromising. As the interaction between the gut microbiota and thyroid cancer has been gradually revealed in recent years, the thyroid gland, a crucial endocrine organ, is shown to have a complex connection with the body's metabolism and is involved in inflammation, autoimmunity, or cancer progression. Dysbiosis of the gut microbiota and its metabolites can influence changes in hormone levels and susceptibility to thyroid cancer through multiple pathways. In this review, we focus on the interactions of the gut microbiota with thyroid function diseases and thyroid cancer. In addition, we also discuss some potential new strategies for the prevention and treatment of thyroid disease and thyroid cancer. Our aim is to provide some possible clinical applications of gut microbiota markers for early diagnosis, treatment, and postoperative management of thyroid cancer. These findings were used to establish a better multi-disciplinary treatment and prevention management strategy and to individualize the treatment of patients in relation to their gut microbiota composition and pathological characteristics.

Suppression of Berberine and Probiotics (in vitro and in vivo) on the Growth of Colon Cancer With Modulation of Gut Microbiota and Butyrate Production

Background and Objective

An increasing number of evidence has revealed that the gut microbiome functions in immunity, inflammation, metabolism, and homeostasis and is considered to be crucial due to its balance between human health and diseases such as cancer, leading to the emergence of treatments that target intestinal microbiota. Probiotics are one of them. However, many challenges remain regarding the effects of probiotics in cancer treatment. Berberine (BBR), a natural extract of Rhizoma Coptidis and extensively used in the treatment of gastrointestinal diseases, has been found to have antitumor effects in vivo and in vitro by many recent studies, but its definite mechanisms are still unclear. This study aimed to explore the inhibitory effect of BBR and probiotics on the growth of colon cancer cells in vitro and in vivo, and the regulatory influence on the gut microbiome and butyrate production.

Methods

Colon cancer cell line HT29 was used to establish a xenograft model of nude mice and an in vitro model. A total of 44 nude mice and HT29 cells were divided into control, model, model + BBR, model + probiotics, and model + combination of BBR with probiotics (CBPs). Live combined Bifidobacterium, Lactobacillus, and Enterococcus powder (LCBLEP) was used as a probiotic preparation. LCBLEP was cultured in the liquid medium under anaerobic conditions (the number of viable bacteria should reach 1 × 10⁸CFU), and the supernatant was collected, and it is called probiotic supernatant (PS). Model + BBR and model + probiotics groups were treated with BBR and LCBLEP or PS for 4 weeks in vivo or 48, 72, and 96 h in vitro, respectively. Tumor volume or cell proliferation was measured. Gut microbiota was pyrosequenced using a 16S rDNA amplicon. HDAC1 mRNA level in HT29 cells and sodium butyrate (SB) expression in the serum of mice was detected by QPCR and ELISA.

Results

The treatment of BBR and CBP reduced the growth of neoplasms in mice to a different extent (p > 0.05), especially at 14 days. The inhibitory effect of LCBLEP on tumor growth was more significant, especially at 11-21 days (p < 0.05). Inhibition of BBR on in vitro proliferation was concentration-dependent. The suppression of 75% probiotic supernatant (PS) on the proliferation was the most significant. The supplement of LCBLEP significantly increased the richness and evenness of the gut microbe. BBR dramatically increased the abundance of Bacteroidetes and Proteobacteria, with reduced Ruminococcus, followed by the LCBLEP. The LCBLEP reduced the relative abundance of Verrucomicrobia and Akkermansia, and the CBP also promoted the relative level of Bacteroidetes but reduced the level of Verrucomicrobia and Akkermansia. BBR and LCBLEP or CBP improved the alpha and beta diversity and significantly affected the biomarker and metabolic function of the gut microbe in nude mice with colon cancer. The level of HDAC1 mRNA was reduced in HT29 cells treated with BBR or PS (p < 0.05), the mice treated with BBR revealed a significantly increased concentration of SB in serum (p < 0.05), and the inhibitory effect of SB on the proliferation of HT29 cells was stronger than panobinostat and TSA.

Conclusion

Although the combination of BBR and probiotics has no advantage in inhibiting tumor growth compared with the drug alone, BBR can be used as a regulator of the intestinal microbiome similar to the probiotics by mediating the production of SB during reducing the growth of colon cancer.

Immunometabolism in biofilm infection: lessons from cancer

BACKGROUND

Biofilm is a community of bacteria embedded in an extracellular matrix, which can colonize different human cells and tissues and subvert the host immune reactions by preventing immune detection and polarizing the immune reactions towards an anti-inflammatory state, promoting the persistence of biofilm-embedded bacteria in the host.

MAIN BODY OF THE MANUSCRIPT

It is now well established that the function of immune cells is ultimately mediated by cellular metabolism. The immune cells are stimulated to regulate their immune functions upon sensing danger signals. Recent studies have determined that immune cells often display distinct metabolic alterations that impair their immune responses when triggered. Such metabolic reprogramming and its physiological implications are well established in cancer situations. In bacterial infections, immuno-metabolic evaluations have primarily focused on macrophages and neutrophils in the planktonic growth mode.

CONCLUSION

Based on differences in inflammatory reactions of macrophages and neutrophils in planktonic- versus biofilm-associated bacterial infections, studies must also consider the metabolic functions of immune cells against biofilm infections. The profound characterization of the metabolic and immune cell reactions could offer exciting novel targets for antibiofilm therapy.

"Driver-passenger" bacteria and their metabolites in the pathogenesis of colorectal cancer

Colorectal cancer (CRC) is a significant public health problem accounting for about 10% of all new cancer cases globally. Though genetic and epigenetic factors influence CRC, the gut microbiota acts as a significant component of the disease's etiology. Further research is still needed to clarify the specific roles and identify more bacteria related to CRC development. This review aims to provide an overview of the "driver-passenger" model of CRC. The colonization and active invasion of the "driver(s)" bacteria cause damages allowing other commensals, known as "passengers," or their by-products, i.e., metabolites, to pass through the epithelium . This review will not only focus on the species of bacteria implicated in this model but also on their biological functions implicated in the occurrence of CRC, such as forming biofilms, mucus, penetration and production of enterotoxins and genotoxins.

Virulent Bacteria as Inflammatory and Immune Co-Factor in Colon Carcinogenesis: Evidence From Two Monozygotic Patients and Validation in CRC Patient and Healthy Cohorts

Colorectal carcinoma (CRC) is a common disease, the incidence of which is increasing according to Western lifestyle; it remains to have a poor prognosis. Western nutriments are presumed to induce mild inflammation within the colonic mucosa, resulting in the accumulation of DNA alterations in colonocytes through a multistage carcinogenesis process. This suggests that most CRCs are related to the environment. Of interest, fecal microbiota composition has been shown yielding a novel approach regarding how environment changes may impact health and disease. Here, we compare whole shotgun metagenomic gut microbiota of two monozygotic twin sisters, one of whom is suffering from an advance colorectal tumor with a profound disequilibrium of the composition of the gut microbiota due to the overexpression of virulent bacteria such as E. coli, Shigella, and Clostridium species in the colon cancer patient’s feces contrasting with low levels of bacterial species such as Faecalibacterium and Akkermansia usually enriched in the healthy adults’ microbial flora. The disequilibrium in microbiota of the CRC patient’s feces as compared to her monozygotic twin sister is linked to inflammatory and immune cell infiltrates in the patient’s colonic tissue. We speculate on the role of microbiota disequilibrium on the immune-tolerant cell infiltrate within CRCs.

Association of Fusobacterium nucleatum infection and colorectal cancer: A Mexican study

INTRODUCTION AND AIMS

Colorectal cancer (CRC) is the third most prevalent cancer worldwide. Many risk factors are involved, and current evidence links the gut microbiota and colorectal carcinogenesis. Fusobacterium nucleatum (F. nucleatum) is proposed as one of the risk factors at the onset and during the progression of CRC, due to immune system and inflammatory modulation.

MATERIALS AND METHODS

Ninety samples from three different regions of the colon were collected through colonoscopy in patients with CRC, and qPCR TagMan® was conducted to detect F. nucleatum and cytokines (IL-17, IL-23, and IL-10) in tumor, peritumor, and normal samples. The differences between them were analyzed and correlated.

RESULTS

The abundance of F. nucleatum determined through the 2^-ΔΔCt method in CRC (7.750 [5.790-10.469]) was significantly higher than in the normal control (0.409 [0.251-0.817]) (p < 0.05). There was no significant association between F. nucleatum and the cytokines (p > 0.05).

CONCLUSIONS

CRC is a heterogeneous disease that presents and progresses in a complex microenvironment, partially due to gut microbiome imbalance. F. nucleatum was enriched in CRC tissue, but whether that is a cause of the pathology or a consequence, has not yet been clearly defined.

Association of Fusobacterium nucleatum infection and colorectal cancer: A Mexican study

INTRODUCTION AND AIMS

Colorectal cancer (CRC) is the third most prevalent cancer worldwide. Many risk factors are involved, and current evidence links the gut microbiota and colorectal carcinogenesis. Fusobacterium nucleatum is proposed as one of the risk factors at the onset and during the progression of CRC, due to immune system and inflammatory modulation.

MATERIALS AND METHODS

Ninety samples from three different regions of the colon were collected through colonoscopy in patients with CRC, and qPCR TagMan® was conducted to detect F. nucleatum and cytokines (IL-17, IL-23, and IL-10) in tumor, peritumor, and normal samples. The differences between them were analyzed and correlated.

RESULTS

The abundance of F. nucleatum determined through the 2-ΔΔCt method in CRC (7.750 [5.790-10.469]) was significantly higher than in the normal control (0.409 [0.251-0.817]) (p<0.05). There was no significant association between F. nucleatum and the cytokines (p>0.05).

CONCLUSIONS

CRC is a heterogeneous disease that presents and progresses in a complex microenvironment, partially due to gut microbiome imbalance. F. nucleatum was enriched in CRC tissue, but whether that is a cause of the pathology or a consequence, has not yet been clearly defined.

Exploring the Role of Gut Microbiome in Colon Cancer

Dysbiosis of the gut microbiome has been associated with the development of colorectal cancer (CRC). Gut microbiota is involved in the metabolic transformations of dietary components into oncometabolites and tumor-suppressive metabolites that in turn affect CRC development. In a healthy colon, the major of microbial metabolism is saccharolytic fermentation pathways. The alpha-bug hypothesis suggested that oncogenic bacteria such as enterotoxigenic Bacteroides fragilis (ETBF) induce the development of CRC through direct interactions with colonic epithelial cells and alterations of microbiota composition at the colorectal site. Escherichia coli, E. faecalis, F. nucleatum, and Streptococcus gallolyticus showed higher abundance whereas Bifidobacterium, Clostridium, Faecalibacterium, and Roseburia showed reduced abundance in CRC patients. The alterations of gut microbiota may be used as potential therapeutic approaches to prevent or treat CRC. Probiotics such as Lactobacillus and Bifidobacterium inhibit the growth of CRC through inhibiting inflammation and angiogenesis and enhancing the function of the intestinal barrier through the secretion of short-chain fatty acids (SCFAs). Crosstalk between lifestyle, host genetics, and gut microbiota is well documented in the prevention and treatment of CRC. Future studies are required to understand the interaction between gut microbiota and host to the influence and prevention of CRC. However, a better understanding of bacterial dysbiosis in the heterogeneity of CRC tumors should also be considered. Metatranscriptomic and metaproteomic studies are considered a powerful omic tool to understand the anti-cancer properties of certain bacterial strains. The clinical benefits of probiotics in the CRC context remain to be determined. Metagenomic approaches along with metabolomics and immunology will open a new avenue for the treatment of CRC shortly. Dietary interventions may be suitable to modulate the growth of beneficial microbiota in the gut.

Crypt residing bacteria and proximal colonic carcinogenesis in a mouse model of Lynch syndrome

Colorectal cancer is a multifactorial disease involving inherited DNA mutations, environmental factors, gut inflammation and intestinal microbiota. Certain germline mutations within the DNA mismatch repair system are associated with Lynch syndrome tumors including right-sided colorectal cancer with mucinous phenotype and presence of an inflammatory infiltrate. Such tumors are more often associated with bacterial biofilms, which may contribute to disease onset and progression. Inflammatory bowel diseases are also associated with colorectal cancer and intestinal dysbiosis. Herein we addressed the question, whether inflammation can aggravate colorectal cancer development under mismatch repair deficiency. MSH2loxP/loxP Vill-cre mice were crossed into the IL-10-/- background to study the importance of inflammation and mucosal bacteria as a driver of tumorigenesis in a Lynch syndrome mouse model. An increase in large bowel tumorigenesis was found in double knockout mice both under conventional housing and under specific pathogen-free conditions. This increase was mostly due to the development of proximal tumors, a hotspot for tumorigenesis in Lynch syndrome, and was associated with a higher degree of inflammation. Additionally, bacterial invasion into the mucus of tumor crypts was observed in the proximal tumors. Inflammation shifted fecal and mucosal microbiota composition and was associated with enrichment in Escherichia-Shigella as well as Akkermansia, Bacteroides and Parabacteroides genera in fecal samples. Tumor-bearing double knockout mice showed a similar enrichment for Escherichia-Shigella and Parabacteroides. Lactobacilli, Lachnospiraceae and Muribaculaceae family members were depleted upon inflammation. In summary, chronic inflammation aggravates colonic tumorigenesis under mismatch repair deficiency and is associated with a shift in microbiota composition.

Microbial Biofilms: Human T-cell Leukemia Virus Type 1 First in Line for Viral Biofilm but Far Behind Bacterial Biofilms

Human T-cell leukemia virus type 1 (HTLV-1) is a retrovirus associated with adult T-cell leukemia (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). To date, it is the unique published example of a virus able to form a biofilm at the surface of infected cells. Deeply studied in bacteria, bacterial biofilms represent multicellular assemblies of bacteria in contact with a surface and shielded by the extracellular matrix (ECM). Microbial lifestyle in biofilms, either viral or bacterial, is opposed structurally and physiologically to an isolated lifestyle, in which viruses or bacteria freely float in their environment. HTLV-1 biofilm formation is believed to be promoted by viral proteins, mainly Tax, through remodeling of the ECM of the infected cells. HTLV-1 biofilm has been linked to cell-to-cell transmission of the virus. However, in comparison to bacterial biofilms, very little is known on kinetics of viral biofilm formation or dissemination, but also on its pathophysiological roles, such as escape from immune detection or therapeutic strategies, as well as promotion of leukemogenesis. The switch between production of cell-free isolated virions and cell-associated viral biofilm, although not fully apprehended yet, remains a key step to understand HTLV-1 infection and pathogenesis.

Toxigenic and non-toxigenic patterns I, II and III and biofilm-forming ability in Bacteroides fragilis strains isolated from patients diagnosed with colorectal cancer

Background

Enterotoxigenic Bacteroides fragilis (ETBF) associated with the initiation and progression of colorectal cancer (CRC) has been alarmingly reported all over the world. In this study, simultaneous investigation of toxigenic and non-toxigenic patterns I, II and III and biofilm formation ability of Bacteroides fragilis isolated from patients with colorectal cancer was performed.

Methods

Thirty-one patients diagnosed with CRC and thirty-one control subjects were recruited in this study. Specimens were cultured on BBE and BBA culture media. Classical phenotypic identification tests and PCR was performed to verify Bacteroides fragilis presence. Also, biofilm-forming ability and expression of bft gene were assessed under biofilm and planktonic forms.

Results

A total of 68 B.fragilis was isolated from all colorectal tissue, of which 13 isolates (19.1%) (11 isolates from CRC and 2 from normal tissue) were positive for bft gene. The abundance patterns of I, II and III were as follow in descending order; pattern I > pattern III > pattern II in CRC subjects and pattern II > pattern III > pattern I in normal tissues. Also, pattern I showed higher biofilm formation ability compared to other patterns. Toxin expression was significantly reduced in biofilm form comparing with planktonic form.

Conclusions

Based on our findings, there was a difference between the abundance of patterns I, II, and III and biofilm formation in isolates obtained from CRC and normal tissues. Biofilm formation ability and toxin encoding gene (bft) are two main virulence factors in B. fragilis pathogenicity which require more investigation to treat B. fragilis infections effectively.

Driver Gene Mutations and Epigenetics in Colorectal Cancer

OBJECTIVE

The majority of patients with colorectal cancer are diagnosed with locally advanced and/or disseminated disease, and treatment options include surgery in combination with cytotoxic chemotherapy regimens, biologics, and/or radiotherapy. Thus, colorectal cancer remains a heavy burden on society and health care systems.Mounting evidence show that driver gene mutations play only part of the role in carcinogenesis. Epigenetics are strongly implicated in initiation and progression of colorectal cancer along with major players such as intestinal microbiotic dysbiosis and chronic mucosal inflammation.To assess phenotypic changes in proteins and gene expression, multigene expression signatures based on sequencing techniques have been developed to hopefully improve predictors of the tumor profile, immune response, and therapeutic outcomes. Our objective was to review current advances in the field and to update surgeons and academics on driver gene mutations and epigenetics in colorectal cancer.

BACKGROUND AND METHODS

This is a narrative review studying relevant research published in the PUBMED database from 2012-2018.

RESULTS AND CONCLUSION

Increased understanding of the molecular biology will improve options to characterize colorectal cancer with regard to mutations and molecular pathways, including microsatellite instability, epigenetics, microbiota, and microenvironment. Research will inevitably improve risk group stratification and targeted treatment approaches.Epigenetic profiling and epigenetic modulating drugs will increase risk stratification, increase accessibility for DNA targeting chemotherapeutics and reduce cytotoxic drug resistance.New generation antibiotics such as biofilm inhibitors and quorum sensing inhibitors are being developed to target the carcinogenetic impact of colonic dysbiosis and inflammation.

Sex Differences in Colon Cancer Metabolism Reveal A Novel Subphenotype

Women have a lower incidence of colorectal cancer (CRC) than men, however, they have a higher incidence of right-sided colon cancer (RCC). This is of concern as patients with RCC have the poorest clinical outcomes among all CRC patients. Aberrant metabolism is a known hallmark and therapeutic target for cancer. We propose that metabolic subphenotypes exist between CRCs due to intertumoral molecular and genomic variation, and differences in environmental milieu of the colon which vary between the sexes. Metabolomics analysis of patient colon tumors (n = 197) and normal tissues (n = 39) revealed sex-specific metabolic subphenotypes dependent on anatomic location. Tumors from women with RCC were nutrient-deplete, showing enhanced energy production to fuel asparagine synthesis and amino acid uptake. The clinical importance of our findings were further investigated in an independent data set from The Cancer Genomic Atlas, and demonstrated that high asparagine synthetase (ASNS) expression correlated with poorer survival for women. This is the first study to show a unique, nutrient-deplete metabolic subphenotype in women with RCC, with implications for tumor progression and outcomes in CRC patients.

Bacterial biofilm in colorectal cancer: What is the real mechanism of action?

Human colorectal cancer is the third most common cancer around the world. Colorectal cancer has various risk factors, but current works have bolded a significant activity for the microbiota of the human colon in the development of this disease. Bacterial biofilm has been mediated to non-malignant pathologies like inflammatory bowel disease but has not been fully documented in the setting of colorectal cancer. The investigation has currently found that bacterial biofilm is mediated to colon cancer in the human and linked to the location of human cancer, with almost all right-sided adenomas of colon cancers possessing bacterial biofilm, whilst left-sided cancer is rarely biofilm positive. The profound comprehension of the changes in colorectal cancer can provide interesting novel concepts for anticancer treatments. In this review, we will summarize and examine the new knowledge about the links between colorectal cancer and bacterial biofilm.

Bacterial Biofilm and its Role in the Pathogenesis of Disease

Recognition of the fact that bacterial biofilm may play a role in the pathogenesis of disease has led to an increased focus on identifying diseases that may be biofilm-related. Biofilm infections are typically chronic in nature, as biofilm-residing bacteria can be resilient to both the immune system, antibiotics, and other treatments. This is a comprehensive review describing biofilm diseases in the auditory, the cardiovascular, the digestive, the integumentary, the reproductive, the respiratory, and the urinary system. In most cases reviewed, the biofilms were identified through various imaging technics, in addition to other study approaches. The current knowledge on how biofilm may contribute to the pathogenesis of disease indicates a number of different mechanisms. This spans from biofilm being a mere reservoir of pathogenic bacteria, to playing a more active role, e.g., by contributing to inflammation. Observations also indicate that biofilm does not exclusively occur extracellularly, but may also be formed inside living cells. Furthermore, the presence of biofilm may contribute to development of cancer. In conclusion, this review shows that biofilm is part of many, probably most chronic infections. This is important knowledge for development of effective treatment strategies for such infections.

Durability and Long-term Clinical Outcomes of Fecal Microbiota Transplant Treatment in Patients With Recurrent Clostridium difficile Infection

Background

Fecal microbiota transplant (FMT) appears safe and effective for treatment of recurrent Clostridium difficile infection (RCDI). However, durability, long-term clinical outcomes, and patient satisfaction after FMT are not well described.

Methods

Eligible patients who received FMT for RCDI at Emory Hospital between 1 July 2012 and 31 December 2016 were contacted via telephone for a follow-up survey. Of 190 eligible patients, 137 (72%) completed the survey.

Results

Median time from last FMT to follow-up was 22 months. Overall, 82% (113/137) of patients at follow-up had no recurrence of C. difficile infection (CDI) post-FMT (non-RCDI group) and 18% (24/137) of patients had CDI post-FMT (RCDI group). Antibiotic exposure for non-CDI infections after FMT was more common in the RCDI group compared to the non-RCDI group (75% vs 38%, P = .0009). Overall, 11% of patients reported improvement or resolution of diagnoses not related to CDI post-FMT, and 33% reported development of a new medical condition or symptom post-FMT. Ninety-five percent of patients (122/128) indicated that they would undergo FMT again, and 70% of these 122 reported that they would prefer FMT to antibiotics as initial treatment if they were to have a CDI recurrence.

Conclusions

In this follow-up survey of outcomes after FMT at a median of 22 months follow-up, 82% of patients had durable cure of CDI. Patients with recurrence had more post-FMT antibiotic exposure, underscoring the need for thoughtful antibiotic use and a potential role for prophylactic microbiome enrichment to reduce recurrence.

Oral Bacteria and Intestinal Dysbiosis in Colorectal Cancer

The human organism coexists with its microbiota in a symbiotic relationship. These polymicrobial communities are involved in many crucial functions, such as immunity, protection against pathogens, and metabolism of dietary compounds, thus maintaining homeostasis. The oral cavity and the colon, although distant anatomic regions, are both highly colonized by distinct microbiotas. However, studies indicate that oral bacteria are able to disseminate into the colon. This is mostly evident in conditions such as periodontitis, where specific bacteria, namely Fusobacterium nucrelatum and Porphyromonas gingivalis project a pathogenic profile. In the colon these bacteria can alter the composition of the residual microbiota, in the context of complex biofilms, resulting in intestinal dysbiosis. This orally-driven disruption promotes aberrant immune and inflammatory responses, eventually leading to colorectal cancer (CRC) tumorigenesis. Understanding the exact mechanisms of these interactions will yield future opportunities regarding prevention and treatment of CRC.

Colonic adenoma-associated Escherichia coli express specific phenotypes

Specific Escherichia coli strains have been associated to colorectal cancer, while no data are available on genotypic and phenotypic features of E. coli colonizing premalignant adenomatous polyps and their pathogenic potential. This study was aimed at characterizing isolates collected from polyps and adjacent tissue in comparison with those from normal mucosa. From colonoscopy biopsies, 1500 E. coli isolates were retrieved and genotyped; 272 were characterized for phylogroup and major phenotypic traits (i.e., biofilm formation, motility, hemolysins, and proteases). Selected isolates were analyzed for extraintestinal pathogenic E. coli (ExPEC)-associated virulence genes and in vivo pathogenicity using Galleria mellonella. The majority of isolates collected from polyps were strong biofilm and poor protease producers, whereas those isolates from normal mucosa were highly motile, proteolytic and weak biofilm formers. Isolates from adjacent tissues shared features with those from both polyps and normal mucosa. Among selected E. coli isolates, ExPEC gene content/profile was variable and uncorrelated with the tissue of collection and larval mortality. Despite the heterogeneous virulence-gene carriage of the E. coli intestinal population, E. coli colonizing colonic adenomatous polyps express specific phenotypic traits that could represent an initial pathoadaptation to local environmental changes characterizing these lesions.

Pathobiont release from dysbiotic gut microbiota biofilms in intestinal inflammatory diseases: a role for iron?

Gut microbiota interacting with an intact mucosal surface are key to the maintenance of homeostasis and health. This review discusses the current state of knowledge of the biofilm mode of growth of these microbiota communities, and how in turn their disruptions may cause disease. Beyond alterations of relative microbial abundance and diversity, the aim of the review is to focus on the disruptions of the microbiota biofilm structure and function, the dispersion of commensal bacteria, and the mechanisms whereby these dispersed commensals may become pathobionts. Recent findings have linked iron acquisition to the expression of virulence factors in gut commensals that have become pathobionts. Causal studies are emerging, and mechanisms common to enteropathogen-induced disruptions, as well as those reported for Inflammatory Bowel Disease and colo-rectal cancer are used as examples to illustrate the great translational potential of such research. These new observations shed new light on our attempts to develop new therapies that are able to protect and restore gut microbiota homeostasis in the many disease conditions that have been linked to microbiota dysbiosis.

Polyamine metabolism and cancer: treatments, challenges and opportunities

Advances in our understanding of the metabolism and molecular functions of polyamines and their alterations in cancer have led to resurgence in the interest of targeting polyamine metabolism as an anticancer strategy. Increasing knowledge of the interplay between polyamine metabolism and other cancer-driving pathways, including the PTEN-PI3K-mTOR complex 1 (mTORC1), WNT signalling and RAS pathways, suggests potential combination therapies that will have considerable clinical promise. Additionally, an expanding number of promising clinical trials with agents targeting polyamines for both therapy and prevention are ongoing. New insights into molecular mechanisms linking dysregulated polyamine catabolism and carcinogenesis suggest additional strategies that can be used for cancer prevention in at-risk individuals. In addition, polyamine blocking therapy, a strategy that combines the inhibition of polyamine biosynthesis with the simultaneous blockade of polyamine transport, can be more effective than therapies based on polyamine depletion alone and may involve an antitumour immune response. These findings open up new avenues of research into exploiting aberrant polyamine metabolism for anticancer therapy.

Bacterial biofilm formation inside colonic crypts may accelerate colorectal carcinogenesis

BACKGROUND

Research in the field of relation between microbes and colorectal carcinogenesis has gained increasing interest in past years. Recently, link between microbial biofilm and carcinogenesis in colon was demonstrated by several authors indicating that biofilm not only is a key player in carcinogenesis, but also may contribute to the understanding of side-specific colon cancer-right sided colon cancer versus left sided. In this article, we briefly highlight the major findings of the research of biofilm and carcinogenesis and demonstrate our findings of colonic cancer tissue and colonic polyp examined for biofilm.

CASE PRESENTATION

Colonic cancer tissue from a patient with a right-sided colon cancer, and an adenoma tubular polyp were examined for biofilm formation by flourescens in situ hybridization. In cancer tissue we found biofilm formation on the surface epithelium but surprisingly also deep into the crypts. No biofilms were found in tubular polyp tissue.

CONCLUSIONS

To our knowledge, this is the first-time biofilm formation deep into colonic crypts are demonstrated in a patient with right-sided colon cancer. This may indicate that bacterial biofilm may have a key role in carcinogenesis.

Relationship of the mucosal microbiota to gastrointestinal inflammation and small cell intestinal lymphoma in cats

Background

The gastrointestinal (GI) microbiota in healthy cats is altered in IBD. Little research has been performed to identify whether specific bacterial groups are associated with small cell GI lymphoma (LSA).

Hypothesis

Mucosal bacteria, including Enterobacteriaceae and Fusobacterium spp., are abundant in intestinal biopsies of cats with small cell GI LSA compared to cats with IBD.

Animals

Fourteen cats with IBD and 14 cats with small cell GI LSA.

Methods

Retrospective case control study. A search of the medical records was performed to identify cats diagnosed with IBD and with GI LSA. Bacterial groups identified by FISH in GI biopsies were compared between cohorts and correlated to CD11b⁺ and NF‐κB expression.

Results

Fusobacterium spp. (median; IQR bacteria/region) were higher in cats with small cell GI LSA in ileal (527; 455.5 – 661.5; P = .046) and colonic (404.5; 328.8 – 455.5; P = .016) adherent mucus, and combined colonic compartments (free mucus, adherent mucus, attaching to epithelium) (8; 0 – 336; P = .017) compared to cats with IBD (ileum: 67; 31.5 – 259; colon: 142.5; 82.3 – 434.5; combined: 3; 0 – 34). Bacteroides spp. were higher in ileal adherent mucus (P = .036) and 3 combined ileal compartments (P = .034) of cats with small cell GI LSA. There were significant correlations between Fusobacterium spp. totals and CD11b⁺ cell (P = .009; rs .476) and NF‐κB expression (P = .004; rs .523).

Conclusions

The bacterial alterations appreciated might be influential in development of small cell GI LSA, and should drive further studies to elucidate the effects of microbial‐mediated inflammation on GI cancer progression.

The Intestinal Microbiota in Colorectal Cancer

Experimental evidence from the past years highlights a key role for the intestinal microbiota in inflammatory and malignant gastrointestinal diseases. Diet exhibits a strong impact on microbial composition and provides risk for developing colorectal carcinoma (CRC). Large metagenomic studies in human CRC associated microbiome signatures with the colorectal adenoma-carcinoma sequence, suggesting a fundamental role of the intestinal microbiota in the evolution of gastrointestinal malignancy. Basic science established a critical function for the intestinal microbiota in promoting tumorigenesis. Further studies are needed to decipher the mechanisms of tumor promotion and microbial co-evolution in CRC, which may be exploited therapeutically in the future.

Human Gut Microbiota and Gastrointestinal Cancer

Human gut microbiota play an essential role in both healthy and diseased states of humans. In the past decade, the interactions between microorganisms and tumors have attracted much attention in the efforts to understand various features of the complex microbial communities, as well as the possible mechanisms through which the microbiota are involved in cancer prevention, carcinogenesis, and anti-cancer therapy. A large number of studies have indicated that microbial dysbiosis contributes to cancer susceptibility via multiple pathways. Further studies have suggested that the microbiota and their associated metabolites are not only closely related to carcinogenesis by inducing inflammation and immune dysregulation, which lead to genetic instability, but also interfere with the pharmacodynamics of anticancer agents. In this article, we mainly reviewed the influence of gut microbiota on cancers in the gastrointestinal (GI) tract (including esophageal, gastric, colorectal, liver, and pancreatic cancers) and the regulation of microbiota by diet, prebiotics, probiotics, synbiotics, antibiotics, or the Traditional Chinese Medicine. We also proposed some new strategies in the prevention and treatment of GI cancers that could be explored in the future. We hope that this review could provide a comprehensive overview of the studies on the interactions between the gut microbiota and GI cancers, which are likely to yield translational opportunities to reduce cancer morbidity and mortality by improving prevention, diagnosis, and treatment.

Human Gut Microbiota and Gastrointestinal Cancer

Human gut microbiota play an essential role in both healthy and diseased states of humans. In the past decade, the interactions between microorganisms and tumors have attracted much attention in the efforts to understand various features of the complex microbial communities, as well as the possible mechanisms through which the microbiota are involved in cancer prevention, carcinogenesis, and anti-cancer therapy. A large number of studies have indicated that microbial dysbiosis contributes to cancer susceptibility via multiple pathways. Further studies have suggested that the microbiota and their associated metabolites are not only closely related to carcinogenesis by inducing inflammation and immune dysregulation, which lead to genetic instability, but also interfere with the pharmacodynamics of anticancer agents. In this article, we mainly reviewed the influence of gut microbiota on cancers in the gastrointestinal (GI) tract (including esophageal, gastric, colorectal, liver, and pancreatic cancers) and the regulation of microbiota by diet, prebiotics, probiotics, synbiotics, antibiotics, or the Traditional Chinese Medicine. We also proposed some new strategies in the prevention and treatment of GI cancers that could be explored in the future. We hope that this review could provide a comprehensive overview of the studies on the interactions between the gut microbiota and GI cancers, which are likely to yield translational opportunities to reduce cancer morbidity and mortality by improving prevention, diagnosis, and treatment.

Biofilm Producing Salmonella Typhi: Chronic Colonization and Development of Gallbladder Cancer

Salmonella enterica subspecies enterica serovar Typhi is the aetiological agent of typhoid or enteric fever. In a subset of individuals, S. Typhi colonizes the gallbladder causing an asymptomatic chronic infection. Nonetheless, these asymptomatic carriers provide a reservoir for further spreading of the disease. Epidemiological studies performed in regions where S. Typhi is endemic, revealed that the majority of chronically infected carriers also harbour gallstones, which in turn, have been indicated as a primary predisposing factor for the onset of gallbladder cancer (GC). It is now well recognised, that S. Typhi produces a typhoid toxin with a carcinogenic potential, that induces DNA damage and cell cycle alterations in intoxicated cells. In addition, biofilm production by S. Typhi may represent a key factor for the promotion of a persistent infection in the gallbladder, thus sustaining a chronic local inflammatory response and exposing the epithelium to repeated damage caused by carcinogenic toxins. This review aims to highlight the putative connection between the chronic colonization by highly pathogenic strains of S. Typhi capable of combining biofilm and toxin production and the onset of GC. Considering the high risk of GC associated with the asymptomatic carrier status, the rapid identification and profiling of biofilm production by S. Typhi strains would be key for effective therapeutic management and cancer prevention.

Environmental influences in the etiology of colorectal cancer: the premise of metabolomics

PURPOSE OF REVIEW

In this review we discuss how environmental exposures predominate the etiology of colorectal cancer (CRC). With CRC being a personalized disease influenced by genes and environment, our goal was to explore the role metabolomics can play in identifying exposures, assessing the interplay between co-exposures, and the development of personalized therapeutic interventions.

RECENT FINDINGS

Approximately 10 % of CRC cases can be explained by germ-line mutations, whereas the prevailing majority are caused by an initiating exposure event occurring decades prior to diagnosis. Recent research has shown that dietary metabolites are linked to a procarcinogenic or protective environment in the colon which is modulated by the microbiome. In addition, excessive alcohol has been shown to increase the risk of CRC and is dependent on diet (folate), the response of microbiome, and genetic polymorphisms within the folate and alcohol metabolic pathways. Metabolomics can not only be used to identify this modulation of host metabolism, which could affect the progression of the tumors but also response to targeted therapeutics.

SUMMARY

This review highlights the current understanding of the multifaceted etiology and mechanisms of CRC development but also highlights where the field of metabolomics can contribute to a greater understanding of environmental exposure in CRC.

Metabolite and Microbiome Interplay in Cancer Immunotherapy

The role of the host microbiome has come to the forefront as a potential modulator of cancer metabolism and could be a future target for precision medicine. A recent study revealed that in colon cancer, bacteria form polysaccharide matrices called biofilms at a high frequency in the proximal colon. Comprehensive untargeted and stable isotope-assisted metabolomic analysis revealed that the bacteria utilize polyamine metabolites produced from colon adenomas/carcinomas to build these protective biofilms and may contribute to inflammation and proliferation observed in colon cancer. This study highlighted the importance of finding the biological origin of a metabolite and assessing its metabolism and mechanism of action. This led to a better understanding of host and microbial interactions, thereby aiding therapeutic design for cancer. In this review, we will discuss methodologies for identifying the biological origin and roles of metabolites in cancer progression and discuss the interactions of the microbiome and metabolites in immunity and cancer treatment, focusing on the flourishing field of cancer immunotherapy. Cancer Res; 76(21); 6146-52. ©2016 AACR.