Campylobacter jejuni promotes colorectal tumorigenesis through the action of cytolethal distending toxin

Microbiota as a New Target in Cancer Pathogenesis and Treatment

The microbial ecosystem of humans is an integral part of human health and disease. A significant percentage of tumors worldwide are thought to be microbially induced. The relationship between cancer and microbes is complex. In this article review, we aim to give an overview of human microbiota and its role in carcinogenesis, emphasize the relation between microbiota and cancer immunity, and highlight its role in the future of cancer therapy. The term microbiota refers to the collection of microorganisms that are located in an individual, whereas the total genome of these microorganisms is referred to as the microbiome. The microbiota in humans has many physiological functions. The microbiota within the gut lumen has a profound effect on the local and systemic immune system. The immune system can change the gut microbiota. Microbiota may induce carcinogenesis by several mechanisms. It also affects tumor progression. Thus, microbiota modulation may aid in the prevention and treatment of cancer. Intentionally introducing microorganisms into the oncological patient is assumed to mobilize the immune system to become able to, at least, limit the development of cancer. Microbes are used as vectors which are carriers of particular antineoplastic agents that reduce the side effects of chemotherapy. Inflammation and tumor microenvironment play an essential role in promoting chemo-resistance. There is now considerable evidence, both in humans as well as in laboratory animals, that the commensal microbiota has important effects on carcinogenesis, tumor growth, and therapy response.

The microbial genotoxin colibactin exacerbates mismatch repair mutations in colorectal tumors

Certain Enterobacteriaceae strains contain a 54-kb biosynthetic gene cluster referred to as "pks" encoding the biosynthesis of a secondary metabolite, colibactin. Colibactin-producing E. coli promote colorectal cancer (CRC) in preclinical models, and in vitro induce a specific mutational signature that is also detected in human CRC genomes. Yet, how colibactin exposure affects the mutational landscape of CRC in vivo remains unclear. Here we show that colibactin-producing E. coli-driven colonic tumors in mice have a significantly higher SBS burden and a larger percentage of these mutations can be attributed to a signature associated with mismatch repair deficiency (MMRd; SBS15), compared to tumors developed in the presence of colibactin-deficient E. coli. We found that the synthetic colibactin 742 but not an inactive analog 746 causes DNA damage and induces transcriptional activation of p53 and senescence signaling pathways in non-transformed human colonic epithelial cells. In MMRd colon cancer cells (HCT 116), chronic exposure to 742 resulted in the upregulation of BRCA1, Fanconi anemia, and MMR signaling pathways as revealed by global transcriptomic analysis. This was accompanied by increased T>N single-base substitutions (SBS) attributed to the proposed pks+E. coli signature (SBS88), reactive oxygen species (SBS17), and mismatch-repair deficiency (SBS44). A significant co-occurrence between MMRd SBS44 and pks-associated SBS88 signature was observed in a large cohort of human CRC patients (n=2,945), and significantly more SBS44 mutations were found when SBS88 was also detected. Collectively, these findings reveal the host response mechanisms underlying colibactin genotoxic activity and suggest that colibactin may exacerbate MMRd-associated mutations.

Bacteria in cancer initiation, promotion and progression

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

Akkermansia muciniphila inhibits tryptophan metabolism via the AhR/β-catenin signaling pathway to counter the progression of colorectal cancer

Akkermansia muciniphila (A. muciniphila), a gram-negative anaerobic bacterium, is selectively decreased in the fecal microbiota of patients with colorectal cancer (CRC), but its molecular mechanism in CRC development remains inconclusive. In this study, we first confirmed the inhibitory effect of A. muciniphila on CRC formation and analyzed the metabolic role of intestinal flora in human Polyps, A-CRA (advanced colorectal adenoma) and CRC samples. To better clarify the role of A. muciniphila in CRC development, a pseudo-germ-free (GF) azoxymethane (AOM)/dextran sulfate sodium (DSS) mouse model was established, followed by infection with or without A. muciniphila. Metabolomic analysis and RNA-seq analysis showed tryptophan-mediated aryl hydrocarbon receptor (AhR) was significantly down-regulated in A. muciniphila-infected CRC mice. Then, mice with intestinal specific AhR deficiency (AhRfl/fl Cre) were generated and were used in 2 murine models: AOM/DSS treatment as a model of carcinogen-induced colon cancer and a genetically induced model using ApcMin/+ mice. Notably, AhR deficiency inhibited CRC growth in the AOM/DSS and ApcMin/+ mouse model. Moreover, AhR deficiency inhibited, rather than enhanced, tumor formation and tumor-derived organoids in Apc-deficient cells both in vivo and in vitro by activating Wnt/β-catenin signaling and TCF4/LEF1-dependent transcription. Furthermore, the antitumor effectiveness of A. muciniphila was abolished either in a human colon cancer tumor model induced by subcutaneous transplantation of AhR-silenced CRC cells, or AhR-deficienty spontaneous colorectal cancer model. In conclusion, supplementation with A. muciniphila. protected mice from CRC development by specifically inhibiting tryptophan-mediated AhR/β-catenin signaling.

Antibodies to oral pathobionts and colon cancer risk in the CLUE I cohort study

Periodontitis has been associated with an increased risk for gastrointestinal cancers. The objective of our study was to investigate the association of antibodies to oral bacteria and the risk of colon cancer in a cohort setting. Using the CLUE I cohort, a prospective cohort initiated in 1974 in Washington County, Maryland, we conducted a nested case-control study to examine the association of levels of IgG antibodies to 11 oral bacterial species (13 total strains) with risk of colon cancer diagnosed a median of 16 years later (range: 1-26 years). Antibody response was measured using checkerboard immunoblotting assays. We included 200 colon cancer cases and 200 controls matched on age, sex, cigarette smoking status, time of blood draw and pipe or cigar smoking status. Controls were selected using incidence density sampling. Conditional logistic regression models were used to assess the association between antibody levels and colon cancer risk. In the overall analysis, we observed significant inverse associations for 6 of the 13 antibodies measured (P-trends <.05) and one positive association for antibody levels to Aggregatibacter actinomycetemcomitans (ATCC 29523; P-trend = .04). While we cannot rule out a role for periodontal disease in colon cancer risk, findings from our study suggest that a strong adaptive immune response may be associated with a lower risk of colon cancer. More studies will need to examine whether the positive associations we observed with antibodies to A. actinomycetemcomitans reflect a true causal association for this bacterium.

Eucommia ulmoides polysaccharide modified nano-selenium effectively alleviated DSS-induced colitis through enhancing intestinal mucosal barrier function and antioxidant capacity

Ulcerative colitis (UC) is currently the most common inflammatory bowel disease (IBD). Due to its diverse and complex causes, there is no cure at present, and researchers are constantly exploring new therapies. In recent years, nano-selenium particle(SeNP) has attracted wide attention due to excellent biological activities. Therefore, in this study, for the first time, we used a natural polysaccharide, Eucommia ulmoides polysaccharide (EUP), modified SeNP to get EUP-SeNP with a size of about 170 nm, and its effect on 3% dextran sulphate sodium (DSS) induced colitis was explored. Our results showed that colon intestinal histology, intestinal mucosal barrier, inflammatory cytokines and intestinal microbiome composition were changed after EUP-SeNP treatment in colitis mice. Specifically, it was also shown that oral treatment of EUP-SeNP could relieve the degree of DSS-induced colitis in mice by restoring weight loss, reducing disease activity index (DAI), enhancing colon antioxidant capacity and regulating intestinal microbiome composition. In addition, we verified the mechanism in intestinal epithelial cell lines, showing that EUP-SeNP inhibited LPS-induced activation of the TRL-4/NF-κB signaling pathway in intestinal epithelial cell lines. To some extend, our study provides therapeutic reference for the treatment of IBD.

Computational methods and challenges in analyzing intratumoral microbiome data

The human microbiome is intimately related to cancer biology and plays a vital role in the efficacy of cancer treatments, including immunotherapy. Extraordinary evidence has revealed that several microbes influence tumor development through interaction with the host immune system, that is, immuno-oncology-microbiome (IOM). This review focuses on the intratumoral microbiome in IOM and describes the available data and computational methods for discovering biological insights of microbial profiling from host bulk, single-cell, and spatial sequencing data. Critical challenges in data analysis and integration are discussed. Specifically, the microorganisms associated with cancer and cancer treatment in the context of IOM are collected and integrated from the literature. Lastly, we provide our perspectives for future directions in IOM research.

Oncogenic potential of Campylobacter infection in the gastrointestinal tract: narrative review

BACKGROUND

Campylobacter jejuni is the leading cause of zoonotic gastroenteritis. The other emerging group of Campylobacters spp. are part of human oral commensal, represented by C. concisus (CC), which has been recently linked to non-oral conditions. Although long-term gastrointestinal (GI) complications from these two groups of Campylobacters have been previously reviewed individually, overall impact of Campylobacter infection on GI carcinogenesis and their inflammatory precursor lesions has not been assessed collectively.

AIMS

To evaluate the available evidence concerning the association between Campylobacter infection/colonization and inflammatory bowel disease (IBD), reflux esophagitis/metaplasia colorectal cancer (CRC) and esophageal cancer (EC).

METHODS

We performed a comprehensive literature search of PubMed for relevant original publications and systematic reviews/meta-analyses of epidemiological and clinical studies. In addition, we gathered additional information concerning microbiological data, animal models and mechanistic data from in vitro studies.

RESULTS

Both retrospective and prospective studies on IBD showed relatively consistent increased risk associated with Campylobacter infection. Despite lack of supporting prospective studies, retrospective studies based on tissue/fecal microbiome revealed consistent enrichment of Campylobacter in CRC samples. Studies on EC precursor lesions (esophagitis and metaplasia) were generally supportive for the association with Campylobacter, while inconsistent observations on EC. Studies on both IBD and EC precursors suggested the predominant role of CC, but studies on CRC were not informative of species.

CONCLUSIONS

There is sufficient evidence calling for concerted effort in unveiling direct and indirect connection of this organism to colorectal and esophageal cancer in humans.

Gut microbiota crosstalk mechanisms are key in pulmonary hypertension: The involvement of melatonin is instrumental too

The microbiota refers to a plethora of microorganisms with a gene pool of approximately three million, which inhabits the human gastrointestinal tract or gut. The latter, not only promotes the transport of nutrients, ions, and fluids from the lumen to the internal environment but is linked with the development of diseases including coronary artery disease, heart failure, and lung diseases. The exact mechanism of how the microbiota achieves crosstalk between itself and distant organs/tissues is not clear, but factors released to other organs may play a role, like inflammatory and genetic factors, and now we highlight melatonin as a novel mediator of the gut-lung crosstalk. Melatonin is present in high concentrations in the gut and the lung and has recently been linked to the pathogenesis of pulmonary hypertension (PH). In this comprehensive review of the literature, we suggest that melatonin is an important link between the gut microbiota and the development of PH (where suppressed melatonin-crosstalk between the gut and lungs could promote the development of PH). More studies are needed to investigate the link between the gut microbiota, melatonin and PH. Studies could also investigate whether microbiota genes play a role in the epigenetic aspects of PH. This is relevant because, for example, dysbiosis (caused by epigenetic factors) could reduce melatonin signaling between the gut and lungs, reduce subcellular melatonin concentrations in the gut/lungs, or reduce melatonin serum levels secondary to epigenetic factors. This area of research is largely unexplored and further studies are warranted.

Association between Gut Microbiota and Digestive System Cancers: A Bidirectional Two-Sample Mendelian Randomization Study

Accumulating evidence indicates that gut microbiota closely correlates with the tumorigenesis of digestive system cancers (DSCs). However, whether the causality between gut microbiota and DSCs exists is unknown. Genome-wide association study (GWAS) summary statistics for gut microbiota and DSCs and the bidirectional two-sample Mendelian randomization (MR) analysis were utilized to assess the causality between gut microbiota and DSCs. Sensitivity analyses were performed to evaluate the robustness of our results. We found that the genus Eggerthella (OR = 0.464, 95%CI: 0.27 to 0.796, p = 0.005) was negatively associated with the risk of gastric cancer. The genetically predicted genus Lachnospiraceae FCS020 group (OR = 0.607, 95%CI: 0.439 to 0.84, p = 0.003) correlated with a lower risk of colorectal cancer, and genus Turicibacter (OR = 0.271, 95%CI: 0.109 to 0.676, p = 0.005) was a protective factor for liver cancer. In the reverse MR, DSCs regulated the relative abundance of specific strains of gut microbiota. We comprehensively screened the association between gut microbiota and DSCs using a bidirectional two-sample MR analysis and identified the causality between several microbial taxa and DSCs. Our discoveries are beneficial for the development of novel microbial markers and microbiota-modifying therapeutics for DSC patients.

Intratumoural microbiota: from theory to clinical application

Cancer is a major cause of high morbidity and mortality worldwide. Several environmental, genetic and lifestyle factors are associated with the development of cancer in humans and result in suboptimal treatment. The human microbiota has been implicated in the pathophysiological process of cancer and has been used as a diagnostic, prognostic and risk assessment tool in cancer management. Notably, both extratumoural and intratumoural microbiota are important components of the tumor microenvironment, subtly influencing tumorigenesis, progression, treatment and prognosis. The potential oncogenic mechanisms of action of the intratumoural microbiota include induction of DNA damage, influence on cell signaling pathways and impairment of immune responses. Some naturally occurring or genetically engineered microorganisms can specifically accumulate and replicate in tumors and then initiate various anti-tumor programs, ultimately promoting the therapeutic effect of tumor microbiota and reducing the toxic and side effects of conventional tumor treatments, which may be conducive to the pursuit of accurate cancer treatment. In this review, we summarise evidence revealing the impact of the intratumoural microbiota on cancer occurrence and progress and potential therapeutic and diagnostic applications, which may be a promising novel strategy to inhibit tumor development and enhance therapeutic efficacy. Video Abstract.

Inhibition of Cancer Development by Natural Plant Polyphenols: Molecular Mechanisms

Malignant tumors remain one of the main sources of morbidity and mortality around the world. A chemotherapeutic approach to cancer treatment poses a multitude of challenges, primarily due to the low selectivity and genotoxicity of the majority of chemotherapeutic drugs currently used in the clinical practice, often leading to treatment-induced tumors formation. Highly selective antitumor drugs can largely resolve this issue, but their high selectivity leads to significant drawbacks due to the intrinsic tumor heterogeneity. In contrast, plant polyphenols can simultaneously affect many processes that are involved in the acquiring and maintaining of hallmark properties of malignant cells, and their toxic dose is typically much higher than the therapeutic one. In the present work we describe the mechanisms of the action of polyphenols on cancer cells, including their effects on genetic and epigenetic instability, tumor-promoting inflammation, and altered microbiota.

Liquid chromatography-tandem mass spectrometry analysis of a ratio-optimized drug pair of Sophora flavescens Aiton and Coptis chinensis Franch and study on the mechanism of anti-colorectal cancer effect of two alkaloids thereof

The drug pair consisting of Sophora flavescens Aiton (Sophorae flavescentis radix, Kushen) and Coptis chinensis Franch. (Coptidis rhizoma, Huanglian), as described in Prescriptions for Universal Relief (Pujifang), is widely used to treat laxation. Matrine and berberine are the major active components of Kushen and Huanglian, respectively. These agents have shown remarkable anti-cancer and anti-inflammatory effects. A mouse model of colorectal cancer was used to determine the most effective combination of Kushen and Huanglian against anti-colorectal cancer. The results showed that the combination of Kushen and Huanglian at a 1:1 ratio exerted the best anti-colorectal cancer effect versus other ratios. Moreover, the anti-colorectal cancer effect and potential mechanism underlying the effects of matrine and berberine were evaluated by the analysis of combination treatment or monotherapy. In addition, the chemical constituents of Kushen and Huanglian were identified and quantified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). A total of 67 chemical components were identified from the Kushen-Huanglian drug pair (water extraction), and the levels of matrine and berberine were 129 and 232 µg/g, respectively. Matrine and berberine reduced the growth of colorectal cancer and relieved the pathological conditions in mice. In addition, the combination of matrine and berberine displayed better anti-colorectal cancer efficacy than monotherapy. Moreover, matrine and berberine reduced the relative abundance of Bacteroidota and Campilobacterota at phylum level and that of Helicobacter, Lachnospiraceae_NK4A136_group, Candidatus_Arthromitus, norank_f_Lachnospiraceae, Rikenella, Odoribacter, Streptococcus, norank_f_Ruminococcaceae, and Anaerotruncus at the genus level. Western blotting results demonstrated that treatment with matrine and berberine decreased the protein expressions of c-MYC and RAS, whereas it increased that of sirtuin 3 (Sirt3). The findings indicated that the combination of matrine and berberine was more effective in inhibiting colorectal cancer than monotherapy. This beneficial effect might depend on the improvement of intestinal microbiota structure and regulation of the RAS/MEK/ERK-c-MYC-Sirt3 signaling axis.

Food System Transformation and Gut Microbiota Transition: Evidence on Advancing Obesity, Cardiovascular Diseases, and Cancers-A Narrative Review

Food, a vital component of our daily life, is fundamental to our health and well-being, and the knowledge and practices relating to food have been passed down from countless generations of ancestors. Systems may be used to describe this extremely extensive and varied body of agricultural and gastronomic knowledge that has been gathered via evolutionary processes. The gut microbiota also underwent changes as the food system did, and these alterations had a variety of effects on human health. In recent decades, the gut microbiome has gained attention due to its health benefits as well as its pathological effects on human health. Many studies have shown that a person's gut microbiota partially determines the nutritional value of food and that diet, in turn, shapes both the microbiota and the microbiome. The current narrative review aims to explain how changes in the food system over time affect the makeup and evolution of the gut microbiota, advancing obesity, cardiovascular disease (CVD), and cancer. After a brief discussion of the food system's variety and the gut microbiota's functions, we concentrate on the relationship between the evolution of food system transformation and gut microbiota system transition linked to the increase of non-communicable diseases (NCDs). Finally, we also describe sustainable food system transformation strategies to ensure healthy microbiota composition recovery and maintain the host gut barrier and immune functions to reverse advancing NCDs.

Bacterial Therapy of Cancer: A Way to the Dustbin of History or to the Medicine of the Future?

Bacteria are the constant companions of the human body throughout its life and even after its death. The history of a human disease such as cancer and the history of microorganisms, particularly bacteria, are believed to closely intertwined. This review was conceived to highlight the attempts of scientists from ancient times to the present day to discover the relationship between bacteria and the emergence or development of tumors in the human body. Challenges and achievements of 21st century science in forcing bacteria to serve for cancer treatment are considered. The future possibilities of bacterial cancer therapy, including the creation of bacterial microrobots, or "bacteriobots", are also discussed.

Esophageal microflora in esophageal diseases

With the development of endoscopic technology, an increasing number of patients with esophageal disease are being diagnosed, although the underlying pathogenesis of many esophageal diseases remains unclear. In recent years, a large number of studies have demonstrated that the occurrence and development of various intestinal diseases were related to intestinal flora. As a result, researchers have shifted their focus towards investigating esophageal flora to better understand the pathogenesis, early diagnosis, and treatment of esophageal diseases. This paper reviewed the normal esophageal flora and the changes of esophageal flora under different esophageal disease states. It was observed that there are distinct differences in the composition of esophageal microflora among Gastroesophageal Reflux, Barrett's esophagus, eosinophilic esophagitis and normal esophagus. The normal esophageal flora was dominated by gram-positive bacteria, particularly Streptococcus, while the esophageal flora under esophagitis was dominated by gram-negative bacteria. Furthermore, the diversity of esophageal flora is significantly decreased in patients with esophageal cancer. Several potential microbial biomarkers for esophageal cancer have been identified, among which Fusobacterium nucleatum showed a close association with esophageal squamous cell carcinoma's pathological stage and clinical stage.

Microbiota regulation in constipation and colorectal cancer

The relevance of constipation to the development and progression of colorectal cancer (CRC) is currently a controversial issue. Studies have shown that changes in the composition of the gut microbiota, a condition known as ecological imbalance, are correlated with an increasing number of common human diseases, including CRC and constipation. CRC is the second leading cause of cancer-related deaths worldwide, and constipation has been receiving widespread attention as a risk factor for CRC. Early colonoscopy screening of constipated patients, with regular follow-ups and timely intervention, can help detect early intestinal lesions and reduce the risks of developing colorectal polyps and CRC. As an important regulator of the intestinal microenvironment, the gut microbiota plays a critical role in the onset and progression of CRC. An increasing amount of evidence supports the thought that gut microbial composition and function are key determinants of CRC development and progression, with alterations inducing changes in the expression of host genes, metabolic regulation, and local and systemic immunological responses. Furthermore, constipation greatly affects the composition of the gut microbiota, which in turn influences the susceptibility to intestinal diseases such as CRC. However, the crosstalk between the gut microbiota, constipation, and CRC is still unclear.

Role of the gut microbiota in anticancer therapy: from molecular mechanisms to clinical applications

In the past period, due to the rapid development of next-generation sequencing technology, accumulating evidence has clarified the complex role of the human microbiota in the development of cancer and the therapeutic response. More importantly, available evidence seems to indicate that modulating the composition of the gut microbiota to improve the efficacy of anti-cancer drugs may be feasible. However, intricate complexities exist, and a deep and comprehensive understanding of how the human microbiota interacts with cancer is critical to realize its full potential in cancer treatment. The purpose of this review is to summarize the initial clues on molecular mechanisms regarding the mutual effects between the gut microbiota and cancer development, and to highlight the relationship between gut microbes and the efficacy of immunotherapy, chemotherapy, radiation therapy and cancer surgery, which may provide insights into the formulation of individualized therapeutic strategies for cancer management. In addition, the current and emerging microbial interventions for cancer therapy as well as their clinical applications are summarized. Although many challenges remain for now, the great importance and full potential of the gut microbiota cannot be overstated for the development of individualized anti-cancer strategies, and it is necessary to explore a holistic approach that incorporates microbial modulation therapy in cancer.

Gut microbiota in colorectal cancer development and therapy

Colorectal cancer (CRC) is one of the commonest cancers globally. A unique aspect of CRC is its intimate association with the gut microbiota, which forms an essential part of the tumour microenvironment. Research over the past decade has established that dysbiosis of gut bacteria, fungi, viruses and Archaea accompanies colorectal tumorigenesis, and these changes might be causative. Data from mechanistic studies demonstrate the ability of the gut microbiota to interact with the colonic epithelia and immune cells of the host via the release of a diverse range of metabolites, proteins and macromolecules that regulate CRC development. Preclinical and some clinical evidence also underscores the role of the gut microbiota in modifying the therapeutic responses of patients with CRC to chemotherapy and immunotherapy. Herein, we summarize our current understanding of the role of gut microbiota in CRC and outline the potential translational and clinical implications for CRC diagnosis, prevention and treatment. Emphasis is placed on how the gut microbiota could now be better harnessed by developing targeted microbial therapeutics as chemopreventive agents against colorectal tumorigenesis, as adjuvants for chemotherapy and immunotherapy to boost drug efficacy and safety, and as non-invasive biomarkers for CRC screening and patient stratification. Finally, we highlight the hurdles and potential solutions to translating our knowledge of the gut microbiota into clinical practice.

Bacterial chemotaxis in human diseases

To infect and cause disease, bacterial pathogens must localize to specific regions of the host where they possess the metabolic and defensive acumen for survival. Motile flagellated pathogens exercise control over their localization through chemotaxis to direct motility based on the landscape of exogenous nutrients, toxins, and molecular cues sensed within the host. Here, we review advances in understanding the roles chemotaxis plays in human diseases. Chemotaxis drives pathogen colonization to sites of inflammation and injury and mediates fitness advantages through accessing host-derived nutrients from damaged tissue. Injury tropism may worsen clinical outcomes through instigating chronic inflammation and subsequent cancer development. Inhibiting bacterial chemotactic systems could act synergistically with antibacterial medicines for more effective and specific eradication.

Identification of a novel gut microbiota signature associated with colorectal cancer in Thai population

Colorectal cancer (CRC) is the third most common cancer worldwide. Dysbiosis of human gut microbiota has been linked to sporadic CRC. This study aimed to compare the gut microbiota profiles of 80 Thai volunteers over 50 years of age among 25 CRC patients, 33 patients with adenomatous polyp, and 22 healthy controls. The 16S rRNA sequencing was utilized to characterize the gut microbiome in both mucosal tissue and stool samples. The results revealed that the luminal microbiota incompletely represented the intestinal bacteria at the mucus layer. The mucosal microbiota in beta diversity differed significantly among the three groups. The stepwise increase of Bacteroides and Parabacteroides according to the adenomas-carcinomas sequence was found. Moreover, linear discriminant analysis effect size showed a higher level of Erysipelatoclostridium ramosum (ER), an opportunistic pathogen in the immunocompromised host, in both sample types of CRC patients. These findings indicated that the imbalance of intestinal microorganisms might involve in CRC tumorigenesis. Additionally, absolute quantitation of bacterial burden by quantitative real-time PCR (qPCR) confirmed the increasing ER levels in both sample types of cancer cases. Using ER as a stool-based biomarker for CRC detection by qPCR could predict CRC in stool samples with a specificity of 72.7% and a sensitivity of 64.7%. These results suggested ER might be a potential noninvasive marker for CRC screening development. However, a larger sample size is required to validate this candidate biomarker in diagnosing CRC.

Bacterial-Mediated Tumor Therapy: Old Treatment in a New Context

Targeted therapy and immunotherapy have brought hopes for precision cancer treatment. However, complex physiological barriers and tumor immunosuppression result in poor efficacy, side effects, and resistance to antitumor therapies. Bacteria-mediated antitumor therapy provides new options to address these challenges. Thanks to their special characteristics, bacteria have excellent ability to destroy tumor cells from the inside and induce innate and adaptive antitumor immune responses. Furthermore, bacterial components, including bacterial vesicles, spores, toxins, metabolites, and other active substances, similarly inherit their unique targeting properties and antitumor capabilities. Bacteria and their accessory products can even be reprogrammed to produce and deliver antitumor agents according to clinical needs. This review first discusses the role of different bacteria in the development of tumorigenesis and the latest advances in bacteria-based delivery platforms and the existing obstacles for application. Moreover, the prospect and challenges of clinical transformation of engineered bacteria are also summarized.

Gut Microbiome Composition and Its Metabolites Are a Key Regulating Factor for Malignant Transformation, Metastasis and Antitumor Immunity

The genetic and metabolomic abundance of the microbiome exemplifies that the microbiome comprises a more extensive set of genes than the entire human genome, which justifies the numerous metabolic and immunological interactions between the gut microbiota, macroorganisms and immune processes. These interactions have local and systemic impacts that can influence the pathological process of carcinogenesis. The latter can be promoted, enhanced or inhibited by the interactions between the microbiota and the host. This review aimed to present evidence that interactions between the host and the gut microbiota might be a significant exogenic factor for cancer predisposition. It is beyond doubt that the cross-talk between microbiota and the host cells in terms of epigenetic modifications can regulate gene expression patterns and influence cell fate in both beneficial and adverse directions for the host's health. Furthermore, bacterial metabolites could shift pro- and anti-tumor processes in one direction or another. However, the exact mechanisms behind these interactions are elusive and require large-scale omics studies to better understand and possibly discover new therapeutic approaches for cancer.

Campylobacter jejuni: targeting host cells, adhesion, invasion, and survival

Campylobacter jejuni, causing strong enteritis, is an unusual bacterium with numerous peculiarities. Chemotactically controlled motility in viscous milieu allows targeted navigation to intestinal mucus and colonization. By phase variation, quorum sensing, extensive O-and N-glycosylation and use of the flagellum as type-3-secretion system C. jejuni adapts effectively to environmental conditions. C. jejuni utilizes proteases to open cell-cell junctions and subsequently transmigrates paracellularly. Fibronectin at the basolateral side of polarized epithelial cells serves as binding site for adhesins CadF and FlpA, leading to intracellular signaling, which again triggers membrane ruffling and reduced host cell migration by focal adhesion. Cell contacts of C. jejuni results in its secretion of invasion antigens, which induce membrane ruffling by paxillin-independent pathway. In addition to fibronectin-binding proteins, other adhesins with other target structures and lectins and their corresponding sugar structures are involved in host-pathogen interaction. Invasion into the intestinal epithelial cell depends on host cell structures. Fibronectin, clathrin, and dynein influence cytoskeletal restructuring, endocytosis, and vesicular transport, through different mechanisms. C. jejuni can persist over a 72-h period in the cell. Campylobacter-containing vacuoles, avoid fusion with lysosomes and enter the perinuclear space via dynein, inducing signaling pathways. Secretion of cytolethal distending toxin directs the cell into programmed cell death, including the pyroptotic release of proinflammatory substances from the destroyed cell compartments. The immune system reacts with an inflammatory cascade by participation of numerous immune cells. The development of autoantibodies, directed not only against lipooligosaccharides, but also against endogenous gangliosides, triggers autoimmune diseases. Lesions of the epithelium result in loss of electrolytes, water, and blood, leading to diarrhea, which flushes out mucus containing C. jejuni. Together with the response of the immune system, this limits infection time. Based on the structural interactions between host cell and bacterium, the numerous virulence mechanisms, signaling, and effects that characterize the infection process of C. jejuni, a wide variety of targets for attenuation of the pathogen can be characterized. The review summarizes strategies of C. jejuni for host-pathogen interaction and should stimulate innovative research towards improved definition of targets for future drug development. KEY POINTS: • Bacterial adhesion of Campylobacter to host cells and invasion into host cells are strictly coordinated processes, which can serve as targets to prevent infection. • Reaction and signalling of host cell depend on the cell type. • Campylobacter virulence factors can be used as targets for development of antivirulence drug compounds.

Molecular Pathways of Carcinogenesis in Familial Adenomatous Polyposis

Familial adenomatous polyposis (FAP) is a genetic syndrome characterized by the presence of multiple polyps in the gastrointestinal tract and a wide range of systemic extra-intestinal manifestations. Patients affected will inevitably undergo abdominal surgery due to the malignant transformation of one or more adenomas. The pathogenesis of the disease is based on a loss of function mutation in adenomatous polyposis coli (APC), a tumor-suppressor gene, inherited following a Mendelian pattern. This gene is a key component of multiple cell functions that cooperate for homeostasis; when mutated, it contributes to the progression of colorectal adenoma into cancer. Recent studies have demonstrated that several additional mechanisms may influence this process, such as alterations in gut microbiota composition and mucosal barrier immunity, interaction with the immune microenvironment and inflammation, the hormone estrogen, and other signaling pathways. These factors represent promising targets of future therapies and chemoprevention, aiming to alter the progressive nature of the disease and improve the quality of life of families affected. Therefore, we performed a narrative review about the current knowledge of the aforementioned pathways involved in colorectal cancer pathogenesis in FAP, exploring the genetic and environmental factors that may contribute to the development of CRC in FAP.

Reprogramming of palmitic acid induced by dephosphorylation of ACOX1 promotes β-catenin palmitoylation to drive colorectal cancer progression

Metabolic reprogramming is a hallmark of cancer. However, it is not well known how metabolism affects cancer progression. We identified that metabolic enzyme acyl-CoA oxidase 1 (ACOX1) suppresses colorectal cancer (CRC) progression by regulating palmitic acid (PA) reprogramming. ACOX1 is highly downregulated in CRC, which predicts poor clinical outcome in CRC patients. Functionally, ACOX1 depletion promotes CRC cell proliferation in vitro and colorectal tumorigenesis in mouse models, whereas ACOX1 overexpression inhibits patient-derived xenograft growth. Mechanistically, DUSP14 dephosphorylates ACOX1 at serine 26, promoting its polyubiquitination and proteasomal degradation, thereby leading to an increase of the ACOX1 substrate PA. Accumulated PA promotes β-catenin cysteine 466 palmitoylation, which inhibits CK1- and GSK3-directed phosphorylation of β-catenin and subsequent β-Trcp-mediated proteasomal degradation. In return, stabilized β-catenin directly represses ACOX1 transcription and indirectly activates DUSP14 transcription by upregulating c-Myc, a typical target of β-catenin. Finally, we confirmed that the DUSP14-ACOX1-PA-β-catenin axis is dysregulated in clinical CRC samples. Together, these results identify ACOX1 as a tumor suppressor, the downregulation of which increases PA-mediated β-catenin palmitoylation and stabilization and hyperactivates β-catenin signaling thus promoting CRC progression. Particularly, targeting β-catenin palmitoylation by 2-bromopalmitate (2-BP) can efficiently inhibit β-catenin-dependent tumor growth in vivo, and pharmacological inhibition of DUSP14-ACOX1-β-catenin axis by Nu-7441 reduced the viability of CRC cells. Our results reveal an unexpected role of PA reprogramming induced by dephosphorylation of ACOX1 in activating β-catenin signaling and promoting cancer progression, and propose the inhibition of the dephosphorylation of ACOX1 by DUSP14 or β-catenin palmitoylation as a viable option for CRC treatment.

Fecal Microbiota Transplantation as a Cancer Therapeutic

ABSTRACT

For decades, cancer research and treatment focused on the cellular level, viewing cancer as a genetic disease of cell transformation. In the era of chemotherapy and radiotherapy, studies from the second half of the 19th century suggesting an association between the microbiota and cancer were almost neglected. The main focus of the field was limited to identification of specific viruses and bacteria that may serve as direct carcinogens leading to the recognition of 7 viruses (i.e., human papillomavirus, hepatitis B virus, and Kaposi sarcoma-associated herpesvirus) and 1 bacterium (Helicobacter pylori) as human carcinogens by the International Agency for Research on Cancer (https://monographs.iarc.who.int/agents-classified-by-the-iarc/). Shortly after the publication of the first draft of the human genome project in February 2001, the Nobel laureate microbiologist Joshua Lederberg raised the question: "Is human identity all in the genes?" It took more than a decade later and the development of multiomic techniques to confirm that his answer "each one of us is a small ecological community" was correct (Lederberg J. Keynote Address: Beyond the Genome. Brooklyn Law Rev 67). This ecological notion became relevant to cancer prevention, prediction, and treatment following the immunotherapy revolution and the understanding of the metabolic and immunologic roles of the microbiota in health and disease. Recently, the microbiota was recognized as an emerging hallmark of cancer following a large body of research showing its role in tumorigenesis, treatment efficacy and toxicity, and initial data regarding the role of microbial modulation in cancer therapy (Cancer Discov 2022;12(1):31-46). In the current review, we will focus on the role of fecal microbiota transplantation, the first microbial modulation technique that is used mainly in low-complexity conditions such as recurrent Clostridium difficile infections (Aliment Pharmacol Ther 2017;46(5):479-493), as a possible cancer therapeutic. However, to better understand the suggested roles of fecal microbiota transplantation in medical oncology, we first need to understand cancer as an ecological niche and the role of the microbiota in tumorigenesis and cancer treatment, specifically immunotherapy.

Overview of methodologies for the culturing, recovery and detection of Campylobacter

Campylobacter species are responsible for human gastroenteritis with diverse clinical spectra, ranging from acute watery or bloody diarrhea to life-threatening autoimmune disorders. Given the importance of Campylobacter in causing human illness, this article has reviewed the transmission and attribution sources as well as methodologies for the detection and virulence characterization of campylobacteria. The recovery and detection of Campylobacter from clinical, food and environmental samples has been achieved by the combinatorial use of selective enrichment and culturing methods. Biochemical, immunological, and nucleic acid-based methodologies have enabled the detection and differentiation of closely related Campylobacter isolates in foodborne outbreak investigations and have assessed the diversity and phylogenetic relationships of these bacterial pathogens. Analyses of motility, adherence, and invasiveness in host cells have assessed the pathogenic potential of campylobacteria. Further examination of determinants conferring antimicrobial resistance in Campylobacter have supported the growing need to closely monitor antimicrobials use in clinical and agricultural sectors.

Seminars in immunology special issue: Nutrition, microbiota and immunity The unexplored microbes in health and disease

Functional characterization of the microbiome's influence on host physiology has been dominated by a few characteristic example strains that have been studied in detail. However, the extensive development of methods for high-throughput bacterial isolation and culture over the past decade is enabling functional characterization of the broader microbiota that may impact human health. Characterizing the understudied majority of human microbes and expanding our functional understanding of the diversity of the gut microbiota could enable new insights into diseases with unknown etiology, provide disease-predictive microbiome signatures, and advance microbial therapeutics. We summarize high-throughput culture-dependent platforms for characterizing bacterial strain function and host-interactions. We elaborate on the importance of these technologies in facilitating mechanistic studies of previously unexplored microbes, highlight new opportunities for large-scale in vitro screens of host-relevant microbial functions, and discuss the potential translational applications for microbiome science.

Genotoxins: The Mechanistic Links between Escherichia coli and Colorectal Cancer

Emerging evidence indicates bacterial infections contribute to the formation of cancers. Bacterial genotoxins are effectors that cause DNA damage by introducing single- and double-strand DNA breaks in the host cells. The first bacterial genotoxin cytolethal distending toxin (CDT) was a protein identified in 1987 in a pathogenic strain in Escherichia coli (E. coli) isolated from a young patient. The peptide-polyketide genotoxin colibactin is produced by the phylogenetic group B₂ of E. coli. Recently, a protein produced by attaching/effacing (A/E) pathogens, including enteropathogenic and enterohemorrhagic E. coli (EPEC and EHEC) and their murine equivalent Citrobacter rodentium (CR), has been reported as a novel protein genotoxin, being injected via the type III secretion system (T3SS) into host cells and harboring direct DNA digestion activity with a catalytic histidine-aspartic acid dyad. These E. coli-produced genotoxins impair host DNA, which results in senescence or apoptosis of the target cells if the damage is beyond repair. Conversely, host cells can survive and proliferate if the genotoxin-induced DNA damage is not severe enough to kill them. The surviving cells may accumulate genomic instability and acquire malignant traits. This review presents the cellular responses of infection with the genotoxins-producing E. coli and discusses the current knowledge of the tumorigenic potential of these toxins.

On the Oral Microbiome of Oral Potentially Malignant and Malignant Disorders: Dysbiosis, Loss of Diversity, and Pathogens Enrichment

The role of dysbiosis in the development and progression of oral potentially malignant disorders (OPMDs) remains largely unknown. Here, we aim to characterize and compare the oral microbiome of homogeneous leucoplakia (HL), proliferative verrucous leukoplakia (PVL), oral squamous cell carcinoma (OSCC), and OSCC preceded by PVL (PVL-OSCC). Fifty oral biopsies from HL (n = 9), PVL (n = 12), OSCC (n = 10), PVL-OSCC (n = 8), and healthy (n = 11) donors were obtained. The sequence of the V3-V4 region of the 16S rRNA gene was used to analyze the composition and diversity of bacterial populations. In the cancer patients, the number of observed amplicon sequence variants (ASVs) was lower and Fusobacteriota constituted more than 30% of the microbiome. PVL and PVL-OSCC patients had a higher abundance of Campilobacterota and lower Proteobacteria than any other group analyzed. A penalized regression was performed to determine which species were able to distinguish groups. HL is enriched in Streptococcus parasanguinis, Streptococcus salivarius, Fusobacterium periodonticum, Prevotella histicola, Porphyromonas pasteri, and Megasphaera micronuciformis; PVL is enriched in Prevotella salivae, Campylobacter concisus, Dialister pneumosintes, and Schaalia odontolytica; OSCC is enriched in Capnocytophaga leadbetteri, Capnocytophaga sputigena, Capnocytophaga gingivalis, Campylobacter showae, Metamycoplasma salivarium, and Prevotella nanceiensis; and PVL-OSCC is enriched in Lachnospiraceae bacterium, Selenomonas sputigena, and Prevotella shahii. There is differential dysbiosis in patients suffering from OPMDs and cancer. To the best of our knowledge, this is the first study comparing the oral microbiome alterations in these groups; thus, additional studies are needed.

Bacteria and macrophages in the tumor microenvironment

Cancer and microbial infections are significant worldwide health challenges. Numerous studies have demonstrated that bacteria may contribute to the emergence of cancer. In this review, we assemble bacterial species discovered in various cancers to describe their variety and specificity. The relationship between bacteria and macrophages in cancer is also highlighted, and we look for ample proof to establish a biological basis for bacterial-induced macrophage polarization. Finally, we quickly go over the potential roles of metabolites, cytokines, and microRNAs in the regulation of the tumor microenvironment by bacterially activated macrophages. The complexity of bacteria and macrophages in cancer will be revealed as we gain a better understanding of their pathogenic mechanisms, which will lead to new therapeutic approaches for both inflammatory illnesses and cancer.

Therapeutic role of ursodeoxycholic acid in colitis-associated cancer via gut microbiota modulation

Inflammatory bowel disease (IBD) is a predisposing factor for colitis-associated cancer (CAC). The association between bile acids and the gut microbiota has been demonstrated in colon neoplasia; however, the effect of ursodeoxycholic acid (UDCA) on gut microbiota alteration in development of colitis and CAC is unknown. Our analysis of publicly available datasets demonstrated the association of UDCA treatment and accumulation of Akkermansia. UDCA-mediated alleviation of DSS-induced colitis was microbially dependent. UDCA treatment significantly upregulated Akkermansia colonization in a mouse model. Colonization of Akkermansia was associated with enhancement of the mucus layer upon UDCA treatment as well as activation of bile acid receptors in macrophages. UDCA played a role in CAC prevention and treatment in the AOM-DSS and ApcMin/+-DSS models through downregulation of inflammation and accumulation of Akkermansia. This study suggests that UDCA intervention could reshape intestinal gut homeostasis, facilitating colonization of Akkermansia and preventing and treating colitis and CAC.

Intestinal organoids as advanced modeling platforms to study the role of host-microbiome interaction in homeostasis and disease

After birth, animals are colonized by a diverse community of microorganisms. The digestive tract is known to contain the largest number of microbiome in the body. With emergence of the gut-brain axis, the importance of gut microbiome and its metabolites in host health has been extensively studied in recent years. The establishment of organoid culture systems has contributed to studying intestinal pathophysiology by replacing current limited models. Owing to their architectural and functional complexity similar to a real organ, co-culture of intestinal organoids with gut microbiome can provide mechanistic insights into the detrimental role of pathobiont and the homeostatic function of commensal symbiont. Here organoid-based bacterial co-culture techniques for modeling host-microbe interactions are reviewed. This review also summarizes representative studies that explore impact of enteric microorganisms on intestinal organoids to provide a better understanding of host-microbe interaction in the context of homeostasis and disease. [BMB Reports 2023; 56(1): 15-23].

Gut Microbiota in Colorectal Cancer: Biological Role and Therapeutic Opportunities

Colorectal cancer (CRC) is the second-leading cause of cancer-related deaths worldwide. While CRC is thought to be an interplay between genetic and environmental factors, several lines of evidence suggest the involvement of gut microbiota in promoting inflammation and tumor progression. Gut microbiota refer to the ~40 trillion microorganisms that inhabit the human gut. Advances in next-generation sequencing technologies and metagenomics have provided new insights into the gut microbial ecology and have helped in linking gut microbiota to CRC. Many studies carried out in humans and animal models have emphasized the role of certain gut bacteria, such as Fusobacterium nucleatum, enterotoxigenic Bacteroides fragilis, and colibactin-producing Escherichia coli, in the onset and progression of CRC. Metagenomic studies have opened up new avenues for the application of gut microbiota in the diagnosis, prevention, and treatment of CRC. This review article summarizes the role of gut microbiota in CRC development and its use as a biomarker to predict the disease and its potential therapeutic applications.

Bacteria derived extracellular vesicles in the pathogenesis and treatment of gastrointestinal tumours

Extracellular vesicles are fundamentally significant in the communication between cells. Outer Membrane Vesicles(OMVs) are a special kind of EVs produced by Gram-negative bacteria, which are minute exosome-like particles budding from the outer membrane, which have been found to play essential roles in diverse bacterial life events, including regulation of microbial interactions, pathogenesis promotion, stress responses and biofilm formation. Recently, and more researches have explored the substantial potentials of EVs as natural functional nanoparticles in the bioengineering applications in infectious diseases, cardiovascular diseases, autoimmune diseases and neurological diseases, such as antibacterial therapy, cancer drugs and immunoadjuvants, with several candidates in clinical trials showing promising efficacy. However, due to the poor understanding of sources, membrane structures and biogenesis mechanisms of EVs, progress in clinical applications still remains timid. In this review, we summarize the latest findings of EVs, especially in gastrointestinal tract tumours, to provide a comprehensive introduction of EVs in tumorigenesis and therapeutics.

Intratumoral microbiota: roles in cancer initiation, development and therapeutic efficacy

Microorganisms, including bacteria, viruses, fungi, and other eukaryotes, play critical roles in human health. An altered microbiome can be associated with complex diseases. Intratumoral microbial components are found in multiple tumor tissues and are closely correlated with cancer initiation and development and therapy efficacy. The intratumoral microbiota may contribute to promotion of the initiation and progression of cancers by DNA mutations, activating carcinogenic pathways, promoting chronic inflammation, complement system, and initiating metastasis. Moreover, the intratumoral microbiota may not only enhance antitumor immunity via mechanisms including STING signaling activation, T and NK cell activation, TLS production, and intratumoral microbiota-derived antigen presenting, but also decrease antitumor immune responses and promote cancer progression through pathways including upregulation of ROS, promoting an anti-inflammatory environment, T cell inactivation, and immunosuppression. The effect of intratumoral microbiota on antitumor immunity is dependent on microbiota composition, crosstalk between microbiota and the cancer, and status of cancers. The intratumoral microbiota may regulate cancer cell physiology and the immune response by different signaling pathways, including ROS, β-catenin, TLR, ERK, NF-κB, and STING, among others. These viewpoints may help identify the microbiota as diagnosis or prognosis evaluation of cancers, and as new therapeutic strategy and potential therapeutic targets for cancer therapy.

EIF3D promotes resistance to 5-fluorouracil in colorectal cancer through upregulating RUVBL1

BACKGROUND

As EIF3D is oncogenic in colorectal cancer (CRC) and is associated with multidrug resistance, this study aims to investigate whether and how EIF3D regulates resistance to 5-fluorouracil (5-Fu) in CRC.

METHODS

EIF3D-associated genes in CRC were predicted using bioinformatics tools. CRC cells and nude mice received 5-Fu treatment. Then, the impacts of EIF3D and the interaction between EIF3D and RUVBL1 on cell viability, colony formation, apoptosis, and DNA damage were detected through MTT, colony formation, flow cytometry, and immunofluorescence assays, and those on in vivo tumorigenesis through murine xenograft assay. IC50 value of 5-Fu for CRC cells was determined by probit regression analysis. Expressions of EIF3D, eIF4E, EIF3D-associated genes, γH2AX, Bcl-2, Bax, and Cleaved Caspase-3/Caspase-3 in CRC tissues, cells, and/or xenograft tumors were analyzed by qRT-PCR and/or Western blot.

RESULTS

EIF3D and RUVBL1 were highly expressed and positively correlated with CRC tissues/cells. In CRC cells, except for eIF4E, both EIF3D and RUVBL1 levels were upregulated by 5-Fu treatment; in addition to that, RUVBL1 level was downregulated by EIF3D silencing rather than eIF4E. Meanwhile, EIF3D silencing diminished IC50 value of 5-Fu and potentiated 5-Fu-induced viability decrease, colony formation inhibition, apoptosis promotion, Bcl-2 downregulation, and γH2AX, Bax, and Cleaved Caspase-3/Caspase-3 upregulation but reversed 5-Fu-triggered RUVBL1 upregulation. RUVBL1 overexpression offsets EIF3D silencing-induced viability decrease and apoptosis promotion of 5-Fu-treated CRC cells, and tumorigenesis suppression and apoptosis promotion in 5-Fu-treated mice.

CONCLUSION

EIF3D promotes resistance to 5-Fu in CRC through upregulating RUVBL1 level.

Gut microbiome in tumorigenesis and therapy of colorectal cancer

Colorectal cancer (CRC) is the malignant tumor with the highest incidence in the digestive system, and the gut microbiome plays a crucial role in CRC tumorigenesis and therapy. The gastrointestinal tract is the organ harboring most of the microbiota in humans. Changes in the gut microbiome in CRC patients suggest possible host-microbe interactions, thereby hinting the potential tumorigenesis, which provides new perspective for preventing, diagnosing, or treating CRC. In this review, we discuss the effects of gut microbiome dysbiosis on CRC, and reveal the mechanisms by which gut microbiome dysbiosis leads to CRC. Gut microbiome modulation with the aim to reverse the established gut microbial dysbiosis is a novel strategy for the prevention and treatment of CRC. In addition, this review summarizes that probiotic antagonize CRC tumorigenesis by protecting intestinal barrier function, inhibiting cancer cell proliferation, resisting oxidative stress, and enhancing host immunity. Finally, we highlight clinical applications of the gut microbiome, such as gut microbiome analysis-based biomarker screening and prediction, and microbe modulation-based CRC prevention, treatment enhancement, and treatment side effect reduction. This review provides the reference for the clinical application of gut microbiome in the prevention and treatment of CRC.

Intratumoral bacteria are an important "accomplice" in tumor development and metastasis

As emerging tumor components, intratumoral bacteria have been found in many solid tumors. Several studies have demonstrated that different cancer subtypes have distinct microbial compositions, and mechanistic studies have shown that intratumoral bacteria may promote cancer initiation and progression through DNA damage, epigenetic modification, inflammatory responses, modulation of host immunity and activation of oncogenes or oncogenic pathways. Moreover, intratumoral bacteria have been shown to modulate tumor metastasis and chemotherapy response. A better understanding of the tumor microenvironment and its associated microbiota will facilitate the design of new metabolically engineered species, opening up a new era of intratumoral bacteria-based cancer therapy. However, many questions remain to be resolved, such as where intratumoral bacteria originate and whether there is a direct causal relationship between intratumoral bacteria and tumor susceptibility. In addition, suitable preclinical models and more advanced detection techniques are crucial for studying the biological functions of intratumoral bacteria. In this review, we summarize the complicated role of intratumoral bacteria in the regulation of cancer development and metastasis and discuss their carcinogenic mechanisms and potential therapeutic aspects.

Intestinal bacteria and colorectal cancer: etiology and treatment

The etiology of colorectal cancer (CRC) is influenced by bacterial communities that colonize the gastrointestinal tract. These microorganisms derive essential nutrients from indigestible dietary or host-derived compounds and activate molecular signaling pathways necessary for normal tissue and immune function. Associative and mechanistic studies have identified bacterial species whose presence may increase CRC risk, including notable examples such as Fusobacterium nucleatum, Enterotoxigenic Bacteroides fragilis, and pks+ E. coli. In recent years this work has expanded in scope to include aspects of host mutational status, intra-tumoral microbial heterogeneity, transient infection, and the cumulative influence of multiple carcinogenic bacteria after sequential or co-colonization. In this review, we will provide an updated overview of how host-bacteria interactions influence CRC development, how this knowledge may be utilized to diagnose or prevent CRC, and how the gut microbiome influences CRC treatment efficacy.

Genetic and environmental reprogramming of the sarcoma epigenome

Sarcomas are rare and heterogenous mesenchymal tumors occurring in soft tissue and bone. The World Health Organization Classification of sarcomas comprises more than hundred different entities which are very diverse in their molecular, genetic and epigenetic signatures as they are in their clinical presentations and behaviors. While sarcomas can be associated with an underlying hereditary cancer predisposition, most sarcomas developed sporadically without identifiable cause. Sarcoma oncogenesis involves complex interactions between genetic, epigenetic and environmental factors which are intimately related and intensively studied. Several molecular discoveries have been made over the last decades leading to the development of new therapeutic avenues. Sarcoma research continues its effort toward a more specific and personalized approach to all sarcoma sub-types to improve patient outcomes and this through world-wide collaboration. This chapter on "Genetic and Environmental Reprogramming of the Sarcoma Epigenome" provides a comprehensive review of general concepts and epidemiology of sarcoma as well as a detailed description of the genetic, molecular and epigenetic alterations seen in sarcomas, their therapeutic implications and ongoing research. This review also presents evidenced-based data on the environmental and occupational factors possibly involved in the etiology of sarcomas and a brief discussion on the role of the microbiome in sarcoma.

Extracellular Vesicles from Campylobacter jejuni CDT-Treated Caco-2 Cells Inhibit Proliferation of Tumour Intestinal Caco-2 Cells and Myeloid U937 Cells: Detailing the Global Cell Response for Potential Application in Anti-Tumour Strategies

Cytolethal distending toxin (CDT) is produced by a range of Gram-negative pathogenic bacteria such as Campylobacter jejuni. CDT represents an important virulence factor that is a heterotrimeric complex composed of CdtA, CdtB, and CdtC. CdtA and CdtC constitute regulatory subunits whilst CdtB acts as the catalytic subunit exhibiting phosphatase and DNase activities, resulting in cell cycle arrest and cell death. Extracellular vesicle (EV) secretion is an evolutionarily conserved process that is present throughout all kingdoms. Mammalian EVs play important roles in regular cell-to-cell communications but can also spread pathogen- and host-derived molecules during infections to alter immune responses. Here, we demonstrate that CDT targets the endo-lysosomal compartment, partially evading lysosomal degradation and exploiting unconventional secretion (EV release), which is largely involved in bacterial infections. CDT-like effects are transferred by Caco-2 cells to uninfected heterologous U937 and homologous Caco-2 cells. The journey of EVs derived from CDT-treated Caco-2 cells is associated with both intestinal and myeloid tumour cells. EV release represents the primary route of CDT dissemination, revealing an active toxin as part of the cargo. We demonstrated that bacterial toxins could represent suitable tools in cancer therapy, highlighting both the benefits and limitations. The global cell response involves a moderate induction of apoptosis and autophagic features may play a protective role against toxin-induced cell death. EVs from CDT-treated Caco-2 cells represent reliable CDT carriers, potentially suitable in colorectal cancer treatments. Our data present a potential bacterial-related biotherapeutic supporting a multidrug anticancer protocol.

MADET: a Manually Curated Knowledge Base for Microbiomic Effects on Efficacy and Toxicity of Anticancer Treatments

A plethora of studies have reported the associations between microbiota and multiple diseases, leading to the development of at least four databases to demonstrate microbiota-disease associations, i.e., gutMDisorder, mBodyMap, Gmrepo, and Amadis. Moreover, gut microbiota mediates drug efficacy and toxicity, whereas a comprehensive database to elucidate the microbiota-drug associations is lacking. Here, we report an open-access knowledge base, MADET (Microbiomics of Anticancer Drug Efficacy and Toxicity), which harbors 483 manually annotated microbiota-drug associations from 26 studies. MADET provides user-friendly functions allowing users to freely browse, search, and download data conveniently from the database. Users can customize their search filters in MADET using different types of keywords, including bacterial name (e.g., Akkermansia muciniphila), anticancer treatment (e.g., anti-PD-1 therapy), and cancer type (e.g., lung cancer) with different types of experimental evidence of microbiota-drug association and causation. We have also enabled user submission to further enrich the data documented in MADET. The MADET database is freely available at https://www.madet.info. We anticipate that MADET will serve as a useful resource for a better understanding of microbiota-drug associations and facilitate the future development of novel biomarkers and live biotherapeutic products for anticancer therapies. IMPORTANCE Human microbiota plays an important role in mediating drug efficacy and toxicity in anticancer treatment. In this work, we developed a comprehensive online database, which documents over 480 microbiota-drug associations manually curated from 26 research articles. Users can conveniently browse, search, and download the data from the database. Search filters can be customized using different types of keywords, including bacterial name (e.g., Akkermansia muciniphila), anticancer treatment (e.g., anti-PD-1 therapy), and cancer type (e.g., lung cancer), with different types of experimental evidence of microbiota-drug association. We anticipate that this database will serve as a convenient platform for facilitating research on microbiota-drug associations, including the development of novel biomarkers for predicting drug outcomes as well as novel live biotherapeutic products for improving the outcomes of anticancer drugs.

Promotion of Deoxycholic Acid Effect on Colonic Cancer Cell Lines In Vitro by Altering the Mucosal Microbiota

Colorectal cancer (CRC) is the third most prevalent neoplasm and the second leading cause of cancer death worldwide. Microbiota and their products, such as bile acids (BAs), are important causal factors for the occurrence and development of CRC. Therefore, we performed 16S ribosomal RNA (16S rRNA) and liquid chromatography/mass spectrometry (LC-MS) to measure mucosal microbiota and BA composition in paired cancerous and noncancerous gut tissue samples from 33 patients with CRC at a hospital in Beijing. In cancerous tissues, we detected altered mucosal microbiota with increased levels of the genera Bacteroides, Curtobacterium, and Campylobacter and an increase in deoxycholic acid (DCA), which was the only BA elevated in cancerous tissues. Ex vivo coculture showed that the mucosal microbiota in cancerous tissues indeed had a stronger DCA production ability, indicating that DCA-producing bacteria are enriched in tumors. Results from the CCK8 and Transwell assays indicated that DCA enhances the overgrowth, migration, and invasion of CRC cell lines, and, through qPCR and Western blot analyses, downregulation of FXR was observed in CRC cell lines after DCA culture. We then verified the downregulation of FXR expression in cancerous tissues using our data and the TCGA database, and we found that FXR downregulation plays an important role in the development of CRC. In conclusion, differing mucosal microbiota, increased amounts of mucosal DCA, and lower FXR expression were demonstrated in cancerous tissues compared to normal tissue samples. The results of this study can be applied to the development of potential therapeutic targets for CRC prevention, such as altering mucosal microbiota, DCA, or FXR.

Metformin in therapeutic applications in human diseases: its mechanism of action and clinical study

Metformin, a biguanide drug, is the most commonly used first-line medication for type 2 diabetes mellites due to its outstanding glucose-lowering ability. After oral administration of 1 g, metformin peaked plasma concentration of approximately 20-30 μM in 3 h, and then it mainly accumulated in the gastrointestinal tract, liver and kidney. Substantial studies have indicated that metformin exerts its beneficial or deleterious effect by multiple mechanisms, apart from AMPK-dependent mechanism, also including several AMPK-independent mechanisms, such as restoring of redox balance, affecting mitochondrial function, modulating gut microbiome and regulating several other signals, such as FBP1, PP2A, FGF21, SIRT1 and mTOR. On the basis of these multiple mechanisms, researchers tried to repurpose this old drug and further explored the possible indications and adverse effects of metformin. Through investigating with clinical studies, researchers concluded that in addition to decreasing cardiovascular events and anti-obesity, metformin is also beneficial for neurodegenerative disease, polycystic ovary syndrome, aging, cancer and COVID-19, however, it also induces some adverse effects, such as gastrointestinal complaints, lactic acidosis, vitamin B12 deficiency, neurodegenerative disease and offspring impairment. Of note, the dose of metformin used in most studies is much higher than its clinically relevant dose, which may cast doubt on the actual effects of metformin on these disease in the clinic. This review summarizes these research developments on the mechanism of action and clinical evidence of metformin and discusses its therapeutic potential and clinical safety.

Genomic insights into zoonotic transmission and antimicrobial resistance in Campylobacter jejuni from farm to fork: a one health perspective

BACKGROUND

Campylobacteriosis represents a global public health threat with various socio-economic impacts. Among different Campylobacter species, Campylobacter jejuni (C. jejuni) is considered to be the foremost Campylobacter species responsible for most of gastrointestinal-related infections. Although these species are reported to primarily inhabit birds, its high genetic and phenotypic diversity allowed their adaptation to other animal reservoirs and to the environment that may impact on human infection.

MAIN BODY

A stringent and consistent surveillance program based on high resolution subtyping is crucial. Recently, different epidemiological investigations have implemented high-throughput sequencing technologies and analytical pipelines for higher resolution subtyping, accurate source attribution, and detection of antimicrobial resistance determinants among these species. In this review, we aim to present a comprehensive overview on the epidemiology, clinical presentation, antibiotic resistance, and transmission dynamics of Campylobacter, with specific focus on C. jejuni. This review also summarizes recent attempts of applying whole-genome sequencing (WGS) coupled with bioinformatic algorithms to identify and provide deeper insights into evolutionary and epidemiological dynamics of C. jejuni precisely along the farm-to-fork continuum.

CONCLUSION

WGS is a valuable addition to traditional surveillance methods for Campylobacter. It enables accurate typing of this pathogen and allows tracking of its transmission sources. It is also advantageous for in silico characterization of antibiotic resistance and virulence determinants, and hence implementation of control measures for containment of infection.