Fusobacterium nucleatum host-cell binding and invasion induces IL-8 and CXCL1 secretion that drives colorectal cancer cell migration

Unveiling the Hidden Links: Periodontal Disease, Fusobacterium Nucleatum, and Cancers

PURPOSE OF REVIEW

Fusobacterium nucleatum (F. nucleatum), an anaerobic, gram-negative microbe, commonly found in human dental biofilm and the gut flora. It has long been known to have a higher concentration in periodontal disease and has recently been implicated in both oral and distant cancers such as colorectal, gastrointestinal, esophageal, breast, pancreatic hepatocellular, and genitourinary cancers. However, the mechanism of its involvement in the development of cancer has not been fully discussed. This review aims to cover biological molecular and clinical aspects of F. nucleatum and cancers.

RECENT FINDINGS

Studies indicate F. nucleatum promotes tumor development through chronic inflammation, immune evasion, cell proliferation activation, and direct cell interactions, as in oral squamous cell carcinoma (OSCC). In colorectal cancer (CRC), F. nucleatum contributes to tumorigenesis through β-catenin signaling and NF-κB activation. It also induces autophagy, leading to chemoresistance in CRC and esophageal cancers, and enhances tumor growth and metastasis in breast cancer by reducing T-cell infiltration. F. nucleatum is linked to carcinogenesis and increased bacterial diversity in OSCC, with improved oral hygiene potentially preventing OSCC. F. nucleatum triggers cancer by causing mutations and epigenetic changes through cytokines and reactive oxygen species. It also promotes chemoresistance in CRC. F. nucleatum may potentially serve as a diagnostic tool in various cancers, with non-invasive detection methods available. Further investigation is needed to discover its potential in the diagnosis and treatment of OSCC and other cancers.

Targeting bacterial metabolites in tumor for cancer therapy: An alternative approach for targeting tumor-associated bacteria

Emerging evidence reveal that tumor-associated bacteria (TAB) can facilitate the initiation and progression of multiple types of cancer. Recent work has emphasized the significant role of intestinal microbiota, particularly bacteria, plays in affecting responses to chemo- and immuno-therapies. Hence, it seems feasible to improve cancer treatment outcomes by targeting intestinal bacteria. While considering variable richness of the intestinal microbiota and diverse components among individuals, direct manipulating the gut microbiota is complicated in clinic. Tumor initiation and progression requires the gut microbiota-derived metabolites to contact and reprogram neoplastic cells. Hence, directly targeting tumor-associated bacteria metabolites may have the potential to provide alternative and innovative strategies to bypass the gut microbiota for cancer therapy. As such, there are great opportunities to explore holistic approaches that incorporates TAB-derived metabolites and related metabolic signals modulation for cancer therapy. In this review, we will focus on key opportunistic areas by targeting TAB-derived metabolites and related metabolic signals, but not bacteria itself, for cancer treatment, and elucidate future challenges that need to be addressed in this emerging field.

Global compositional and functional states of the human gut microbiome in health and disease

The human gut microbiota is of increasing interest, with metagenomics a key tool for analyzing bacterial diversity and functionality in health and disease. Despite increasing efforts to expand microbial gene catalogs and an increasing number of metagenome-assembled genomes, there have been few pan-metagenomic association studies and in-depth functional analyses across different geographies and diseases. Here, we explored 6014 human gut metagenome samples across 19 countries and 23 diseases by performing compositional, functional cluster, and integrative analyses. Using interpreted machine learning classification models and statistical methods, we identified Fusobacterium nucleatum and Anaerostipes hadrus with the highest frequencies, enriched and depleted, respectively, across different disease cohorts. Distinct functional distributions were observed in the gut microbiomes of both westernized and nonwesternized populations. These compositional and functional analyses are presented in the open-access Human Gut Microbiome Atlas, allowing for the exploration of the richness, disease, and regional signatures of the gut microbiota across different cohorts.

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

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

Gut bacteria, host immunity, and colorectal cancer: From pathogenesis to therapy

The emergence of 16S rRNA and metagenomic sequencing has gradually revealed the close relationship between dysbiosis and colorectal cancer (CRC). Recent studies have confirmed that intestinal dysbiosis plays various roles in the occurrence, development, and therapeutic response of CRC. Perturbation of host immunity is one of the key mechanisms involved. The intestinal microbiota, or specific bacteria and their metabolites, can modulate the progression of CRC through pathogen recognition receptor signaling or via the recruitment, polarization, and activation of both innate and adaptive immune cells to reshape the protumor/antitumor microenvironment. Therefore, the administration of gut bacteria to enhance immune homeostasis represents a new strategy for the treatment of CRC. In this review, we cover recent studies that illuminate the role of gut bacteria in the progression and treatment of CRC through orchestrating the immune response, which potentially offers insights for subsequent transformative research.

Curcumin and its anti-colorectal cancer potential: From mechanisms of action to autophagy

Colorectal cancer (CRC) development and progression, one of the most common cancers globally, is supported by specific mechanisms to escape cell death despite chemotherapy, including cellular autophagy. Autophagy is an evolutionarily highly conserved degradation pathway involved in a variety of cellular processes, such as the maintenance of cellular homeostasis and clearance of foreign bodies, and its imbalance is associated with many diseases. However, the role of autophagy in CRC progression remains controversial, as it has a dual function, affecting either cell death or survival, and is associated with cellular senescence in tumor therapy. Indeed, numerous data have been presented that autophagy in cancers serves as an alternative to cell apoptosis when the latter is ineffective or in apoptosis-resistant cells, which is why it is also referred to as programmed cell death type II. Curcumin, one of the active constituents of Curcuma longa, has great potential to combat CRC by influencing various cellular signaling pathways and epigenetic regulation in a safe and cost-effective approach. This review discusses the efficacy of curcumin against CRC in vitro and in vivo, particularly its modulation of autophagy and apoptosis in various cellular pathways. While clinical studies have assessed the potential of curcumin in cancer prevention and treatment, none have specifically examined its role in autophagy. Nonetheless, we offer an overview of potential correlations to support the use of this polyphenol as a prophylactic or co-therapeutic agent in CRC.

An emerging antibacterial nanovaccine for enhanced chemotherapy by selectively eliminating tumor-colonizing bacteria

Fusobacterium nucleatum (F. nucleatum), an oral anaerobe, is prevalent in colorectal cancer and is closely related to increased cancer cell growth, metastasis, and poor treatment outcomes. Bacterial vaccines capable of selectively eliminating bacteria present a promising approach to targeting intratumor F. nucleatum, thereby enhancing cancer treatment. Although adjuvants have been employed to enhance the immune response, the vaccine's effectiveness is constrained by inadequate T-cell activation necessary for eradicating intracellular pathogens. In this study, we developed a minimalistic, biomimetic nanovaccine by integrating highly immunostimulatory adjuvant cholesterol-modified CpG oligonucleotides into the autologously derived F. nucleatum membranes. Compared to the traditional vaccines consisting of inactivated bacteria and Alum adjuvant, the nanovaccine coupled with bacterial membranes and adjuvants could remarkably improve multiple antigens and adjuvant co-delivery to dendritic cells, maximizing their ability to achieve effective antigen presentation and strong downstream immune progress. Notably, the nanovaccine exhibits outstanding selective prophylactic and therapeutic effects, eliminating F. nucleatum without affecting intratumoral and gut microbiota. It significantly enhances chemotherapy efficacy and reduces cancer metastasis in F. nucleatum-infected colorectal cancer. Overall, this work represents the rational application of bacterial nanovaccine and provides a blueprint for future development in enhancing the antitumor effect against bacterial-infected cancer.

The Crucial Role of Inflammation and the Immune System in Colorectal Cancer Carcinogenesis: A Comprehensive Perspective

Chronic inflammation drives the growth of colorectal cancer through the dysregulation of molecular pathways within the immune system. Infiltration of immune cells, such as macrophages, into tumoral regions results in the release of proinflammatory cytokines (IL-6; IL-17; TNF-α), fostering tumor proliferation, survival, and invasion. Tumors employ various mechanisms to evade immune surveillance, effectively 'cloaking' themselves from detection and subsequent attack. A comprehensive understanding of these intricate molecular interactions is paramount for advancing novel strategies aimed at modulating the immune response against cancer.

Advances in the isolation, cultivation, and identification of gut microbes

The gut microbiome is closely associated with human health and the development of diseases. Isolating, characterizing, and identifying gut microbes are crucial for research on the gut microbiome and essential for advancing our understanding and utilization of it. Although culture-independent approaches have been developed, a pure culture is required for in-depth analysis of disease mechanisms and the development of biotherapy strategies. Currently, microbiome research faces the challenge of expanding the existing database of culturable gut microbiota and rapidly isolating target microorganisms. This review examines the advancements in gut microbe isolation and cultivation techniques, such as culturomics, droplet microfluidics, phenotypic and genomics selection, and membrane diffusion. Furthermore, we evaluate the progress made in technology for identifying gut microbes considering both non-targeted and targeted strategies. The focus of future research in gut microbial culturomics is expected to be on high-throughput, automation, and integration. Advancements in this field may facilitate strain-level investigation into the mechanisms underlying diseases related to gut microbiota.

Electro-antibacterial therapy (EAT) to enhance intracellular bacteria clearance in pancreatic cancer cells

Intratumoral bacteria have been implicated in driving tumor progression, yet effective treatments to modulate the tumor microbiome remain limited. In this study, we investigate the use of electroporation in combination with metronidazole to enhance the clearance of intracellular Fusobacterium nucleatum within pancreatic cancer cells. We explore various parameters, including electric field strength, pulse width, and pulse number to assess the permeability of pancreatic cancer cells infected with F. nucleatum, compared to non-infected cells of the same type. We subsequently quantify the clearance of intracellular bacteria when these pulsing schemes are applied to a suspension of infected pancreatic cancer cells in the presence of metronidazole. Our results reveal distinct differences in cell permeability between infected and non-infected cells, identifying a unique biophysical marker for host cells infected with F. nucleatum. We demonstrate that the combinatorial use of electroporation and metronidazole significantly enhances the delivery of metronidazole into host cells, leading to more effective clearance of intracellular F. nucleatum compared to independent treatments; we term this novel approach Electro-Antibacterial Therapy (EAT). EAT holds promise as an innovative strategy for addressing intratumoral bacteria in pancreatic cancer, other malignancies, and potentially treatment-resistant infections, offering new avenues for therapeutic intervention.

Interaction of microbiota, mucosal malignancies, and immunotherapy-Mechanistic insights

The microbiome has emerged as a crucial modulator of host-immune interactions and clearly impacts tumor development and therapy efficacy. The microbiome is a double-edged sword in cancer development and therapy as both pro-tumorigenic and anti-tumorigenic bacterial taxa have been identified. The staggering number of association-based studies in various tumor types has led to an enormous amount of data that makes it difficult to identify bacteria that promote tumor development or modulate therapy efficacy from bystander bacteria. Here we aim to comprehensively summarize the current knowledge of microbiome-host immunity interactions and cancer therapy in various mucosal tissues to find commonalities and thus identify potential functionally relevant bacterial taxa. Moreover, we also review recent studies identifying specific bacteria and mechanisms through which the microbiome modulates cancer development and therapy efficacy.

Natural polysaccharides regulate intestinal microbiota for inhibiting colorectal cancer

The gastrointestinal tract is an important part of the human immune system. The gut microbiome, which constitutes a major component of the gastrointestinal tract, plays a crucial role in maintaining normal physiological functions and influences the development, diagnosis, and immunotherapy of colorectal cancer (CRC). Natural polysaccharides can be extracted from animals, plants, and traditional Chinese medicines. They serve as an essential energy source for the gut microbiome, promoting probiotic proliferation and regulating the intestinal microecological balance. Moreover, polysaccharides exhibit anti-tumor effects due to their immune regulatory functions and low toxicity. This review focuses on discussing these anti-tumor effects in CRC, along with improving gut microbiome dysbiosis and regulating the tumor immune microenvironment, providing evidence for effective therapeutic strategies against CRC.

Fusobacterium nucleatum infection modulates the transcriptome and epigenome of HCT116 colorectal cancer cells in an oxygen-dependent manner

Fusobacterium nucleatum, a gram-negative oral bacterium, has been consistently validated as a strong contributor to the progression of several types of cancer, including colorectal (CRC) and pancreatic cancer. While previous in vitro studies have shown that intracellular F. nucleatum enhances malignant phenotypes such as cell migration, the dependence of this regulation on features of the tumor microenvironment (TME) such as oxygen levels are wholly uncharacterized. Here we examine the influence of hypoxia in facilitating F. nucleatum invasion and its effects on host responses focusing on changes in the global epigenome and transcriptome. Using a multiomic approach, we analyze epigenomic alterations of H3K27ac and global transcriptomic alterations sustained within a hypoxia and normoxia conditioned CRC cell line HCT116 at 24 h following initial infection with F. nucleatum. Our findings reveal that intracellular F. nucleatum activates signaling pathways and biological processes in host cells similar to those induced upon hypoxia conditioning in the absence of infection. Furthermore, we show that a hypoxic TME favors F. nucleatum invasion and persistence and therefore infection under hypoxia may amplify malignant transformation by exacerbating the effects induced by hypoxia alone. These results motivate future studies to investigate host-microbe interactions in tumor tissue relevant conditions that more accurately define parameters for targeted cancer therapies.

Engineering lauric acid-based nanodrug delivery systems for restoring chemosensitivity and improving biocompatibility of 5-FU and OxPt against Fn-associated colorectal tumor

Colorectal cancer (CRC) occurs in the colorectum and ranks second in the global incidence of all cancers, accounting for one of the highest mortalities. Although the combination chemotherapy regimen of 5-fluorouracil (5-FU) and platinum(IV) oxaliplatin prodrug (OxPt) is an effective strategy for CRC treatment in clinical practice, chemotherapy resistance caused by tumor-resided Fusobacterium nucleatum (Fn) could result in treatment failure. To enhance the efficacy and improve the biocompatibility of combination chemotherapy, we developed an antibacterial-based nanodrug delivery system for Fn-associated CRC treatment. A tumor microenvironment-activated nanomedicine 5-FU-LA@PPL was constructed by the self-assembly of chemotherapeutic drug derivatives 5-FU-LA and polymeric drug carrier PPL. PPL is prepared by conjugating lauric acid (LA) and OxPt to hyperbranched polyglycidyl ether. In principle, LA is used to selectively combat Fn, inhibit autophagy in CRC cells, restore chemosensitivity of 5-FU as well as OxPt, and consequently enhance the combination chemotherapy effects for Fn-associated drug-resistant colorectal tumor. Both in vitro and in vivo studies exhibited that the tailored nanomedicine possessed efficient antibacterial and anti-tumor activities with improved biocompatibility and reduced non-specific toxicity. Hence, this novel anti-tumor strategy has great potential in the combination chemotherapy of CRC, which suggests a clinically relevant valuable option for bacteria-associated drug-resistant cancers.

The role of CXCL2-mediated crosstalk between tumor cells and macrophages in Fusobacterium nucleatum-promoted oral squamous cell carcinoma progression

Dysbiosis of the oral microbiota is related to chronic inflammation and carcinogenesis. Fusobacterium nucleatum (Fn), a significant component of the oral microbiota, can perturb the immune system and form an inflammatory microenvironment for promoting the occurrence and progression of oral squamous cell carcinoma (OSCC). However, the underlying mechanisms remain elusive. Here, we investigated the impacts of Fn on OSCC cells and the crosstalk between OSCC cells and macrophages. 16 s rDNA sequencing and fluorescence in situ hybridization verified that Fn was notably enriched in clinical OSCC tissues compared to paracancerous tissues. The conditioned medium co-culture model validated that Fn and macrophages exhibited tumor-promoting properties by facilitating OSCC cell proliferation, migration, and invasion. Besides, Fn and OSCC cells can recruit macrophages and facilitate their M2 polarization. This crosstalk between OSCC cells and macrophages was further enhanced by Fn, thereby amplifying this positive feedback loop between them. The production of CXCL2 in response to Fn stimulation was a significant mediator. Suppression of CXCL2 in OSCC cells weakened Fn's promoting effects on OSCC cell proliferation, migration, macrophage recruitment, and M2 polarization. Conversely, knocking down CXCL2 in macrophages reversed the Fn-induced feedback effect of macrophages on the highly invasive phenotype of OSCC cells. Mechanistically, Fn activated the NF-κB pathway in both OSCC cells and macrophages, leading to the upregulation of CXCL2 expression. In addition, the SCC7 subcutaneous tumor-bearing model in C3H mice also substantiated Fn's ability to enhance tumor progression by facilitating cell proliferation, activating NF-κB signaling, up-regulating CXCL2 expression, and inducing M2 macrophage infiltration. However, these effects were reversed by the CXCL2-CXCR2 inhibitor SB225002. In summary, this study suggests that Fn contributes to OSCC progression by promoting tumor cell proliferation, macrophage recruitment, and M2 polarization. Simultaneously, the enhanced CXCL2-mediated crosstalk between OSCC cells and macrophages plays a vital role in the pro-cancer effect of Fn.

Role of imbalanced gut microbiota in promoting CRC metastasis: from theory to clinical application

Metastasis poses a major challenge in colorectal cancer (CRC) treatment and remains a primary cause of mortality among patients with CRC. Recent investigations have elucidated the involvement of disrupted gut microbiota homeostasis in various facets of CRC metastasis, exerting a pivotal influence in shaping the metastatic microenvironment, triggering epithelial-mesenchymal transition (EMT), and so on. Moreover, therapeutic interventions targeting the gut microbiota demonstrate promise in enhancing the efficacy of conventional treatments for metastatic CRC (mCRC), presenting novel avenues for mCRC clinical management. Grounded in the "seed and soil" hypothesis, this review consolidates insights into the mechanisms by which imbalanced gut microbiota promotes mCRC and highlights recent strides in leveraging gut microbiota modulation for the clinical prevention and treatment of mCRC. Emphasis is placed on the considerable potential of manipulating gut microbiota within clinical settings for managing mCRC.

Transcriptome fine-mapping in Fusobacterium nucleatum reveals FoxJ, a new σE-dependent small RNA with unusual mRNA activation activity

The oral commensal Fusobacterium nucleatum can spread to extra-oral sites, where it is associated with diverse pathologies, including pre-term birth and cancer. Due to the evolutionary distance of F. nucleatum to other model bacteria, we lack a deeper understanding of the RNA regulatory networks that allow this bacterium to adapt to its various niches. As a first step in that direction, we recently showed that F. nucleatum harbors a global stress response governed by the extracytoplasmic function sigma factor, σE, which displays a striking functional conservation with Proteobacteria and includes a noncoding arm in the form of a regulatory small RNA (sRNA), FoxI. To search for putative additional σE-dependent sRNAs, we comprehensively mapped the 5' and 3' ends of transcripts in the model strain ATCC 23726. This enabled the discovery of FoxJ, a ~156-nucleotide sRNA previously misannotated as the 5' untranslated region (UTR) of ylmH. FoxJ is tightly controlled by σE and activated by the same stress conditions as is FoxI. Both sRNAs act as mRNA repressors of the abundant porin FomA, but FoxJ also regulates genes that are distinct from the target suite of FoxI. Moreover, FoxJ differs from other σE-dependent sRNAs in that it also positively regulates genes at the post-transcriptional level. We provide preliminary evidence for a new mode of sRNA-mediated mRNA activation, which involves the targeting of intra-operonic terminators. Overall, our study provides an important resource through the comprehensive annotation of 5' and 3' UTRs in F. nucleatum and expands our understanding of the σE response in this evolutionarily distant bacterium.IMPORTANCEThe oral microbe Fusobacterium nucleatum can colonize secondary sites, including cancer tissue, and likely deploys complex regulatory systems to adapt to these new environments. These systems are largely unknown, partly due to the phylogenetic distance of F. nucleatum to other model organisms. Previously, we identified a global stress response mediated by σE that displays functional conservation with the envelope stress response in Proteobacteria, comprising a coding and noncoding regulatory arm. Through global identification of transcriptional start and stop sites, we uncovered the small RNA (sRNA) FoxJ as a novel component of the noncoding arm of the σE response in F. nucleatum. Together with its companion sRNA FoxI, FoxJ post-transcriptionally modulates the synthesis of envelope proteins, revealing a conserved function for σE-dependent sRNAs between Fusobacteriota and Proteobacteria. Moreover, FoxJ activates the gene expression for several targets, which is a mode of regulation previously unseen in the noncoding arm of the σE response.

Bacteriome and mycobiome dysbiosis in oral mucosal dysplasia and oral cancer

It has long been considered that the oral microbiome is tightly connected to oral health and that dysbiotic changes can be detrimental to the occurrence and progression of dysplastic oral mucosal lesions or oral cancer. Improved understanding of the concepts of microbial dysbiosis together with advances in high-throughput molecular sequencing of these pathologies have charted in greater microbiological detail the nature of their clinical state. This review discusses the bacteriome and mycobiome associated with oral mucosal lesions, oral candidiasis, and oral squamous cell carcinoma, aiming to delineate the information available to date in pursuit of advancing diagnostic and prognostic utilities for oral medicine.

Promising dawn in tumor microenvironment therapy: engineering oral bacteria

Despite decades of research, cancer continues to be a major global health concern. The human mouth appears to be a multiplicity of local environments communicating with other organs and causing diseases via microbes. Nowadays, the role of oral microbes in the development and progression of cancer has received increasing scrutiny. At the same time, bioengineering technology and nanotechnology is growing rapidly, in which the physiological activities of natural bacteria are modified to improve the therapeutic efficiency of cancers. These engineered bacteria were transformed to achieve directed genetic reprogramming, selective functional reorganization and precise control. In contrast to endotoxins produced by typical genetically modified bacteria, oral flora exhibits favorable biosafety characteristics. To outline the current cognitions upon oral microbes, engineered microbes and human cancers, related literatures were searched and reviewed based on the PubMed database. We focused on a number of oral microbes and related mechanisms associated with the tumor microenvironment, which involve in cancer occurrence and development. Whether engineering oral bacteria can be a possible application of cancer therapy is worth consideration. A deeper understanding of the relationship between engineered oral bacteria and cancer therapy may enhance our knowledge of tumor pathogenesis thus providing new insights and strategies for cancer prevention and treatment.

Fusobacterium nucleatum subsp. polymorphum recovered from malignant and potentially malignant oral disease exhibit heterogeneity in adhesion phenotypes and adhesin gene copy number, shaped by inter-subspecies horizontal gene transfer and recombination-derived mosaicism

Fusobacterium nucleatum is an anaerobic commensal of the oral cavity associated with periodontitis and extra-oral diseases, including colorectal cancer. Previous studies have shown an increased relative abundance of this bacterium associated with oral dysplasia or within oral tumours. Using direct culture, we found that 75 % of Fusobacterium species isolated from malignant or potentially malignant oral mucosa were F. nucleatum subsp. polymorphum. Whole genome sequencing and pangenome analysis with Panaroo was carried out on 76 F. nucleatum subsp. polymorphum genomes. F. nucleatum subsp. polymorphum was shown to possesses a relatively small core genome of 1604 genes in a pangenome of 7363 genes. Phylogenetic analysis based on the core genome shows the isolates can be separated into three main clades with no obvious genotypic associations with disease. Isolates recovered from healthy and diseased sites in the same patient are generally highly related. A large repertoire of adhesins belonging to the type V secretion system (TVSS) could be identified with major variation in repertoire and copy number between strains. Analysis of intergenic recombination using fastGEAR showed that adhesin complement is shaped by horizontal gene transfer and recombination. Recombination events at TVSS adhesin genes were not only common between lineages of subspecies polymorphum, but also between different subspecies of F. nucleatum. Strains of subspecies polymorphum with low copy numbers of TVSS adhesin encoding genes tended to have the weakest adhesion to oral keratinocytes. This study highlights the genetic heterogeneity of F. nucleatum subsp. polymorphum and provides a new framework for defining virulence in this organism.

The Microbiome Matters: Its Impact on Cancer Development and Therapeutic Responses

In the evolving landscape of cancer research, the human microbiome emerges as a pivotal determinant reshaping our understanding of tumorigenesis and therapeutic responses. Advanced sequencing technologies have uncovered a vibrant microbial community not confined to the gut but thriving within tumor tissues. Comprising bacteria, viruses, and fungi, this diverse microbiota displays distinct signatures across various cancers, with most research primarily focusing on bacteria. The correlations between specific microbial taxa within different cancer types underscore their pivotal roles in driving tumorigenesis and influencing therapeutic responses, particularly in chemotherapy and immunotherapy. This review amalgamates recent discoveries, emphasizing the translocation of the oral microbiome to the gut as a potential marker for microbiome dysbiosis across diverse cancer types and delves into potential mechanisms contributing to cancer promotion. Furthermore, it highlights the adverse effects of the microbiome on cancer development while exploring its potential in fortifying strategies for cancer prevention and treatment.

Gut microbiota and epigenetics in colorectal cancer: implications for carcinogenesis and therapeutic intervention

Colorectal cancer (CRC) is a leading cause of cancer-related deaths worldwide. The occurrence of CRC is associated with various genetic and epigenetic mutations in intestinal epithelial cells that transform them into adenocarcinomas. There is increasing evidence indicating the gut microbiota plays a crucial role in the regulation of host physiological processes. Alterations in gut microbiota composition are responsible for initiating carcinogenesis through diverse epigenetic modifications, including histone modifications, ncRNAs and DNA methylation. This work was designed to comprehensively review recent findings to provide insight into the associations between the gut microbiota and CRC at an epigenetic level. These scientific insights can be used in the future to develop effective strategies for early detection and treatment of CRC.

Recent Aspects of Periodontitis and Alzheimer's Disease-A Narrative Review

Periodontitis is an inflammatory condition affecting the supporting structures of the teeth. Periodontal conditions may increase the susceptibility of individuals to various systemic illnesses, including Alzheimer's disease. Alzheimer's disease is a neurodegenerative condition characterized by a gradual onset and progressive deterioration, making it the primary cause of dementia, although the exact cause of the disease remains elusive. Both Alzheimer's disease and periodontitis share risk factors and clinical studies comparing the associations and occurrence of periodontitis among individuals with Alzheimer's disease have suggested a potential correlation between these conditions. Brains of individuals with Alzheimer's disease have substantiated the existence of microorganisms related to periodontitis, especially Porphyromonas gingivalis, which produces neurotoxic gingipains and may present the capability to breach the blood-brain barrier. Treponema denticola may induce tau hyperphosphorylation and lead to neuronal apoptosis. Lipopolysaccharides-components of bacterial cell membranes and mediators of inflammation-also have an impact on brain function. Further research could unveil therapeutic approaches targeting periodontal pathogens to potentially alleviate AD progression.

Drug delivery systems for enhanced tumour treatment by eliminating intra-tumoral bacteria

Cancer remains one of the serious threats to human health. The relationship between bacteria and various tumours has been widely reported in recent years, and studies on intra-tumoral bacteria have become important as intra-tumoral bacteria directly affect the tumorigenesis, progression, immunity and metastatic processes. Therefore, eliminating these commensal intra-tumoral bacteria while treating tumour is expected to be a potential strategy to further enhance the clinical outcome of tumour therapy. Drug delivery systems (DDSs) are widely used to deliver antibiotics and chemotherapeutic drugs for antibacterial and anticancer applications, respectively. Thus, this review firstly provides a comprehensive summary of the association between intra-tumoral bacteria and a host of tumours, followed by a description of advanced DDSs for improving the therapeutic efficacy of cancer treatment through the elimination of intra-tumoral bacteria. It is hoped that this review will provide guidelines for the therapeutic and "synergistic antimicrobial and antitumour" drug delivery strategy.

Melanoma and microbiota: Current understanding and future directions

Over the last decade, the composition of the gut microbiota has been found to correlate with the outcomes of cancer patients treated with immunotherapy. Accumulating evidence points to the various mechanisms by which intestinal bacteria act on distal tumors and how to harness this complex ecosystem to circumvent primary resistance to immune checkpoint inhibitors. Here, we review the state of the microbiota field in the context of melanoma, the recent breakthroughs in defining microbial modes of action, and how to modulate the microbiota to enhance response to cancer immunotherapy. The host-microbe interaction may be deciphered by the use of "omics" technologies, and will guide patient stratification and the development of microbiota-centered interventions. Efforts needed to advance the field and current gaps of knowledge are also discussed.

Porphyromonas gingivalis fuels colorectal cancer through CHI3L1-mediated iNKT cell-driven immune evasion

The interaction between the gut microbiota and invariant Natural Killer T (iNKT) cells plays a pivotal role in colorectal cancer (CRC). The pathobiont Fusobacterium nucleatum influences the anti-tumor functions of CRC-infiltrating iNKT cells. However, the impact of other bacteria associated with CRC, like Porphyromonas gingivalis, on their activation status remains unexplored. In this study, we demonstrate that mucosa-associated P. gingivalis induces a protumour phenotype in iNKT cells, subsequently influencing the composition of mononuclear-phagocyte cells within the tumor microenvironment. Mechanistically, in vivo and in vitro experiments showed that P. gingivalis reduces the cytotoxic functions of iNKT cells, hampering the iNKT cell lytic machinery through increased expression of chitinase 3-like-1 protein (CHI3L1). Neutralization of CHI3L1 effectively restores iNKT cell cytotoxic functions suggesting a therapeutic potential to reactivate iNKT cell-mediated antitumour immunity. In conclusion, our data demonstrate how P. gingivalis accelerates CRC progression by inducing the upregulation of CHI3L1 in iNKT cells, thus impairing their cytotoxic functions and promoting host tumor immune evasion.

Fusobacterium nucleatum promotes inflammatory and anti-apoptotic responses in colorectal cancer cells via ADP-heptose release and ALPK1/TIFA axis activation

The anaerobic bacterium Fusobacterium nucleatum is significantly associated with human colorectal cancer (CRC) and is considered a significant contributor to the disease. The mechanisms underlying the promotion of intestinal tumor formation by F. nucleatum have only been partially uncovered. Here, we showed that F. nucleatum releases a metabolite into the microenvironment that strongly activates NF-κB in intestinal epithelial cells via the ALPK1/TIFA/TRAF6 pathway. Furthermore, we showed that the released molecule had the biological characteristics of ADP-heptose. We observed that F. nucleatum induction of this pathway increased the expression of the inflammatory cytokine IL-8 and two anti-apoptotic genes known to be implicated in CRC, BIRC3 and TNFAIP3. Finally, it promoted the survival of CRC cells and reduced 5-fluorouracil chemosensitivity in vitro. Taken together, our results emphasize the importance of the ALPK1/TIFA pathway in Fusobacterium induced-CRC pathogenesis, and identify the role of ADP-H in this process.

Spatial transcriptomic analysis reveals local effects of intratumoral fusobacterial infection on DNA damage and immune signaling in rectal cancer

Mucinous colorectal cancer (CRC) is a common histological subtype of colorectal adenocarcinoma, associated with a poor response to chemoradiotherapy. The commensal facultative anaerobes fusobacteria, have been associated with poor prognosis specifically in mesenchymal CRC. Interestingly, fusobacterial infection is especially prevalent in mucinous CRC. The objective of this study was therefore to increase our understanding of beneficial and detrimental effects of fusobacterial infection, by contrasting host cell signaling and immune responses in areas of high vs. low infection, using mucinous rectal cancer as a clinically relevant example. We employed spatial transcriptomic profiling of 106 regions of interest from 8 mucinous rectal cancer samples to study gene expression in the epithelial and immune segments across regions of high versus low fusobacterial infection. Fusobacteria high regions were associated with increased oxidative stress, DNA damage, and P53 signaling. Meanwhile regions of low fusobacterial prevalence were characterized by elevated JAK-STAT, Il-17, Il-1, chemokine and TNF signaling. Immune masks within fusobacterial high regions were characterized by elevated proportions of cytotoxic (CD8+) T cells (p = 0.037), natural killer (NK) cells (p < 0.001), B-cells (p < 0.001), and gamma delta T cells (p = 0.003). Meanwhile, fusobacteria low regions were associated with significantly greater M2 macrophage (p < 0.001), fibroblast (p < 0.001), pericyte (p = 0.002), and endothelial (p < 0.001) counts.

Discovery of New Fusobacterium nucleatum Inhibitors to Attenuate Migratory Capability of Colon Cancer Cells by the Drug Repositioning Strategy

Recent studies revealed that intestinal microbiota played important roles in colorectal cancer (CRC) carcinogenesis. Particularly, Fusobacterium nucleatum was confirmed to promote the proliferation and metastasis of CRC. Therefore, targeting F. nucleatum may be a potential preventive and therapeutic approach for CRC. Herein, 2,272 off-patent drugs were screened inhibitory activity against F. nucleatum. Among the hits, nitisinone was identified as a promising anti-F. nucleatum lead compound. Further optimization of nitisinone led to the discovery of more potent derivatives. Particularly, compounds 19q and 22c showed potent anti-F. nucleatum activity (MIC50 = 1 and 2 μg/mL, respectively) with low cytotoxicity. Among them, compound 19q effectively attenuated the migratory ability of MC-38 cells induced by F. nucleatum. Preliminary mechanism studies suggested that nitisinone and its derivatives might act by downregulating nitroreductase and tryptophanase. Thus, the development of small molecule F. nucleatum inhibitors represents an effective strategy to treat CRC.

CXCL1 promotes immune escape in colorectal cancer by autophagy-mediated MHC-I degradation

BACKGROUND

Immunotherapy is now seen as a potential remedy for colorectal cancer (CRC). Chemokines play a crucial role in tumors, including CRC, which contains CXCL1. We attempted to study how CXCL1 impacts immune escape in CRC.

METHODS

Bioinformatics analysis was used to examine CXCL1 level in CRC. qRT-PCR was used to assess CXCL1 and MHC-I (HLA-A, B, C) levels. Cell Counting Kit-8 (CCK-8) was used to measure cell viability. Cytotoxicity assay kit was utilized to assay CD8+ T cell cytotoxicity against CRC. Flow cytometry tested proliferation and apoptosis of CD8+ T cells. Chemotaxis assay evaluated chemotaxis of CD8+ T cells towards CRC. Immunofluorescence examined expression of autophagy marker LC3 and localization of NBR1/MHC-I. Western blot analysis measured protein levels of chemokines CXCL9 and CXCL10, autophagy-related proteins LC3-I and LC3-II, and MHC-I (HLA-A, B, C).

RESULTS

Bioinformatics analysis and qRT-PCR presented that CXCL1 was upregulated in CRC. Cell experiments demonstrated that CXCL1 overexpression promoted immune escape in CRC. Rescue experiments revealed that the autophagy inducer Rapa could attenuate the inhibitory effect of CXCL1 low expression on immune escape in CRC. Further studies showed that CXCL1 promoted immune escape in CRC by autophagy-mediated MHC-I degradation.

CONCLUSION

CXCL1 promoted immune escape in CRC by autophagy-mediated MHC-I degradation, suggesting that CXCL1 may be a possible immunotherapeutic target for CRC.

Gut microbial signatures are associated with Lynch syndrome (LS) and cancer history in Druze communities in Israel

Lynch syndrome (LS) is a hereditary cancer syndrome caused by autosomal dominant mutations, with high probability of early onset for several cancers, mainly colorectal cancer (CRC). The gut microbiome was shown to be influenced by host genetics and to be altered during cancer development. Therefore, we aimed to determine alterations in gut microbiome compositions of LS patients with and without cancer. We performed fecal microbiome analyses on samples of LS and non-LS members from the Druze ethnoreligious community in Israel, based on both their LS mutation and their cancer history. Our analysis revealed specific bacterial operational taxonomic units (OTUs) overrepresented in LS individuals as well as bacterial OTUs differentiating between the LS individuals with a history of cancer. The identified OTUs align with previous studies either correlating them to pro-inflammatory functions, which can predispose to cancer, or to the cancer itself, and as such, these bacteria can be considered as future therapeutic targets.

Bacterial infection and microbiota in carcinogenesis and tumor development

Microbiota colonize exposed body tissues (e.g., gastrointestinal tract, skin, lungs, female genital tract, and urogenital tracts) and unexposed sites (e.g., breast). Persistent bacterial infection in the host lead to the development of multiple disease. They are implicated in the pathogenesis of various complex diseases, including diabetes, atherosclerosis, autoimmune diseases, Alzheimer's disease, and malignant diseases. Amounting studies have demonstrated the role of bacterial infection in carcinogenesis. The study of microbiota in tumorigenesis is primarily focused on lung cancer, colorectal cancer (CRC), breast cancer, gastric cancer, and gynecologic tumors, and so on. Infection of Helicobacter pylori in gastric cancer carcinogenesis is recognized as class I carcinogen by the World Health Organization (WHO) decades ago. The role of Fusobacterium nucleatum in the development of colorectal cancer is extensively investigated. Variable bacteria have been cultured from the tumor tissues. The identification of microbiota in multiple tumor tissues reveal that bacterial infection and microbiota are associated with tumor development. The microbiota affects multiple aspects of carcinogenesis and tumor development, including favoring epithelial cells proliferation, establishing inflammatory microenvironment, promoting metastasis, and causing resistance to therapy. On the other hand, microbiota can shape a tumor surveillance environment by enhancing cell activity, and sensitize the tumor cells to immune therapy. In the present review, the roles of microbiota in multiple malignancies are summarized, and unraveling the mechanisms of host-microbiota interactions can contribute to a better understanding of the interaction between microbiota and host cells, also the development of potential anti-tumor therapeutic strategies.

The oral-gut-circulatory axis: from homeostasis to colon cancer

The human microbiota is widely recognized as providing crucial health benefits to its host, specifically by modulating immune homeostasis. Microbial imbalance, known as dysbiosis, is linked to several conditions in the body. The oral cavity and gut host the two largest microbial communities playing a major role in microbial-associated diseases. While the oral-gut axis has been previously explored, our review uniquely highlights the significance of incorporating the circulatory system into this axis. The interaction between immune cells, inflammatory factors, circulating bacteria, and microbial metabolites influences the homeostasis of both the oral and gut microbiota in a bidirectional manner. In this comprehensive review, we aim to describe the bacterial components of the oral-gut-circulatory axis in both health and disease, with a specific focus on colon cancer.

Fusobacterium nucleatum infection activates the noncanonical inflammasome and exacerbates inflammatory response in DSS-induced colitis

Caspase activation results in pyroptosis, an inflammatory cell death that contributes to several inflammatory diseases by releasing inflammatory cytokines and cellular contents. Fusobacterium nucleatum is a periodontal pathogen frequently detected in human cancer and inflammatory bowel diseases. Studies have reported that F. nucleatum infection leads to NLRP3 activation and pyroptosis, but the precise activation process and disease association remain poorly understood. This study demonstrated that F. nucleatum infection exacerbates acute colitis in mice and activates pyroptosis through caspase-11-mediated gasdermin D cleavage in macrophages. Furthermore, F. nucleatum infection in colitis mice induces the enhancement of IL-1⍺ secretion from the colon, affecting weight loss and severe disease activities. Neutralization of IL-1⍺ protects F. nucleatum infected mice from severe colitis. Therefore, F. nucleatum infection facilitates inflammation in acute colitis with IL-1⍺ from colon tissue by activating noncanonical inflammasome through gasdermin D cleavage.

Antibacterial Fusobacterium nucleatum-Mimicking Nanomedicine to Selectively Eliminate Tumor-Colonized Bacteria and Enhance Immunotherapy Against Colorectal Cancer

Clinical evidence indicates that tumor-colonizing bacteria can be closely related to the tumor development and therapeutic responses. Selectively eliminating bacteria within tumors may be an attractive approach to enhance cancer treatment without additional side effects. Herein, it is found that, owing to the high affinity between the membrane protein Fap-2 on Fusobacterium nucleatum and d-galactose-β (1-3)-N-acetyl-d-galactosamine (Gal-GalNAc) overexpressed on colorectal tumor cells, F. nucleatum can colonize in colorectal tumors, as evidenced by both clinical samples and animal tumor models. Notably, F. nucleatum colonized in colorectal tumors can lead to an immunosuppressive tumor microenvironment, greatly reducing their responses to immune checkpoint blockade (ICB) therapy. Inspired by this finding, an F. nucleatum-mimetic nanomedicine is designed by fusing F. nucleatum cytoplasmic membrane (FM) with Colistin-loaded liposomes to achieve selective killing of tumor-colonizing F. nucleatum without affecting gut microbes. As a result, the therapeutic responses of F. nucleatum-colonized tumors to ICB therapies can be successfully restored, as demonstrated in an F. nucleatum-infected subcutaneous CT-26 tumor model, chemically induced spontaneous colorectal cancer models, and MC-38 tumor model. In summary, this work presents an F. nucleatum-mimicking nanomedicine that can selectively eliminate tumor-colonized bacteria, which is promising for enhancing the responses of cancer immunotherapy against F. nucleatum-colonized colorectal cancer.

Fusobacterium nucleatum upregulates MMP7 to promote metastasis-related characteristics of colorectal cancer cell via activating MAPK(JNK)-AP1 axis

BACKGROUND

Colorectal cancer (CRC) is the third most common malignant tumor. Fusobacterium nucleatum (F. nucleatum) is overabundant in CRC and associated with metastasis, but the role of F. nucleatum in CRC cell migration and metastasis has not been fully elucidated.

METHODS

Differential gene analysis, protein-protein interaction, robust rank aggregation analysis, functional enrichment analysis, and gene set variation analysis were used to figure out the potential vital genes and biological functions affected by F. nucleatum infection. The 16S rDNA sequencing and q-PCR were used to detect the abundance of F. nucleatum in tissues and stools. Then, we assessed the effect of F. nucleatum on CRC cell migration by wound healing and transwell assays, and confirmed the role of Matrix metalloproteinase 7 (MMP7) induced by F. nucleatum in cell migration. Furthermore, we dissected the mechanisms involved in F. nucleatum induced MMP7 expression. We also investigated the MMP7 expression in clinical samples and its correlation with prognosis in CRC patients. Finally, we screened out potential small molecular drugs that targeted MMP7 using the HERB database and molecular docking.

RESULTS

F. nucleatum infection altered the gene expression profile and affected immune response, inflammation, biosynthesis, metabolism, adhesion and motility related biological functions in CRC. F. nucleatum was enriched in CRC and promoted the migration of CRC cell by upregulating MMP7 in vitro. MMP7 expression induced by F. nucleatum infection was mediated by the MAPK(JNK)-AP1 axis. MMP7 was highly expressed in CRC and correlated with CMS4 and poor clinical prognosis. Small molecular drugs such as δ-tocotrienol, 3,4-benzopyrene, tea polyphenols, and gallic catechin served as potential targeted therapeutic drugs for F. nucleatum induced MMP7 in CRC.

CONCLUSIONS

Our study showed that F. nucleatum promoted metastasis-related characteristics of CRC cell by upregulating MMP7 via MAPK(JNK)-AP1 axis. F. nucleatum and MMP7 may serve as potential therapeutic targets for repressing CRC advance and metastasis.

Intracellular bacteria in cancer-prospects and debates

Recent evidence suggests that some human cancers may harbor low-biomass microbial ecosystems, spanning bacteria, viruses, and fungi. Bacteria, the most-studied kingdom in this context, are suggested by these studies to localize within cancer cells, immune cells and other tumor microenvironment cell types, where they are postulated to impact multiple cancer-related functions. Herein, we provide an overview of intratumoral bacteria, while focusing on intracellular bacteria, their suggested molecular activities, communication networks, host invasion and evasion strategies, and long-term colonization capacity. We highlight how the integration of sequencing-based and spatial techniques may enable the recognition of bacterial tumor niches. We discuss pitfalls, debates and challenges in decisively proving the existence and function of intratumoral microbes, while reaching a mechanistic elucidation of their impacts on tumor behavior and treatment responses. Together, a causative understanding of possible roles played by intracellular bacteria in cancer may enable their future utilization in diagnosis, patient stratification, and treatment.

Molecular Pathogenesis of Colitis-associated Colorectal Cancer: Immunity, Genetics, and Intestinal Microecology

Patients with inflammatory bowel disease (IBD) have a high risk for colorectal cancer (CRC). This cancer type, which is strongly associated with chronic inflammation, is called colitis-associated CRC (CAC). Understanding the molecular pathogenesis of CAC is crucial to identify biomarkers necessary for early diagnosis and more effective treatment directions. The accumulation of immune cells and inflammatory factors, which constitute a complex chronic inflammatory environment in the intestinal mucosa, may cause oxidative stress or DNA damage to the epithelial cells, leading to CAC development and progression. An important feature of CAC is genetic instability, which includes chromosome instability, microsatellite instability, hypermethylation, and changes in noncoding RNAs. Furthermore, the intestinal microbiota and metabolites have a great impact on IBD and CAC. By clarifying immune, genetic, intestinal microecology, and other related pathogenesis, CAC may be more predictable and treatable.

Class I HLA Allele Predicted Restricted Antigenic Coverages for Fap2 Protein of Fusobacterium Nucleatum Are Associated with Colorectal Cancer Incidence

OBJECTIVE

This study investigates the association between HLA-A and -B allele diversity, Fusobacterium nucleatum Fap2 protein-derived antigenic coverage, and colorectal cancer (CRC) epidemiology across diverse populations.

METHODS

We examined 75 HLA-I alleles and explored 698 potential HLA-A and B-restricted Fap2-derived antigens, assessing how 21 countries may respond to these peptides based on their HLA-I distribution frequencies. Additionally, we correlated in-silico predicted Fap2 population coverage with CRC epidemiology. CRC incidence and mortality data were obtained from the Global Cancer Observatory, and HLA-A and HLA-B allele frequencies from the Allele Frequency Net Database. Binding predictions for Fap2 antigens were performed using netMHCpan4, with stringent selection criteria applied to identify relevant peptides. Population coverage was calculated using the IEDB population coverage tool, and data analysis conducted using the R programming language.

RESULTS

Clustering of HLA-A and -B allele frequencies partially differentiated countries with lower CRC incidence from others. Distinct patterns of Fap2 protein coverage were observed among different populations. interestingly, we found a significant inverse correlation between CRC incidence (p = 0.0037, R = -0.6) and predicted Fap2 antigen coverage, as well as CRC mortality (p = 0.013, R = -0.53). Furthermore, we identified a specific set of Fap2-derived peptides that bind to HLA supertypes, providing a global coverage of 99.04%.

CONCLUSION

Our population-based study is the first to demonstrate that higher Fap2 coverage is associated with lower CRC incidence, underscoring the potential significance of Fap2-specific CD8+ T cell responses in CRC tumorigenesis.

Microorganism-regulated autophagy in gastrointestinal cancer

Gastrointestinal cancer has always been one of the most urgent problems to be solved, and it has become a major global health issue. Microorganisms in the gastrointestinal tract regulate normal physiological and pathological processes. Accumulating evidence reveals the role of the imbalance in the microbial community during tumorigenesis. Autophagy is an important intracellular homeostatic process, where defective proteins and organelles are degraded and recycled under stress. Autophagy plays a dual role in tumors as both tumor suppressor and tumor promoter. Many studies have shown that autophagy plays an important role in response to microbial infection. Here, we provide an overview on the regulation of the autophagy signaling pathway by microorganisms in gastrointestinal cancer.

Gut microbiota and microbiota-derived metabolites in colorectal cancer: enemy or friend

Colorectal cancer (CRC) is a highly prevalent gastrointestinal cancer worldwide. Recent research has shown that the gut microbiota plays a significant role in the development of CRC. There is mounting evidence supporting the crucial contributions of bacteria-derived toxins and metabolites to cancer-related inflammation, immune imbalances, and the response to therapy. Besides, some gut microbiota and microbiota-derived metabolites have protective effects against CRC. This review aims to summarize the current studies on the effects and mechanisms of gut microbiota and microbiota-produced metabolites in the initiation, progression, and drug sensitivity/resistance of CRC. Additionally, we explore the clinical implications and future prospects of utilizing gut microbiota as innovative approaches for preventing and treating CRC.

The role of lncRNAs and exosomal lncRNAs in cancer metastasis

Tumor metastasis is the main reason for cancer-related death, but there is still a lack of effective therapeutic to inhibit tumor metastasis. Therefore, the discovery and study of new tumor metastasis regulators is a prominent measure for cancer diagnosis and treatment. Long non-coding RNA (lncRNA) is a type of non-coding RNAs over 200 bp in length. It has been shown that the abnormally expressed lncRNAs promote tumor metastasis by participating in the epithelial-to-mesenchymal transition (EMT) process, altering the metastatic tumor microenvironment, or changing the extracellular matrix. It is,thus, critical to explore the regulation of lncRNAs expression in cells and the molecular mechanism of lncRNA-mediated cancer metastasis. Simultaneously, it has been shown that lncRNA is one kind of the main components of exosomes, which protects lncRNAs from being rapidly degraded. Meanwhile, the components of exosomes are parent-specific, making exosomal lncRNAs to be potential tumor metastasis markers and therapeutic targets. In view of this, we also summarized the aberrant enrichment of lncRNAs in exosomes and their role in metastatic cancer. The aberrant lncRNAs and exosomal lncRNAs gradually become biomarkers and therapeutic targets for tumor metastatic, and the potential of lncRNAs in therapeutics are studied here. Besides, the lncRNA-related databases, which could greatly facilitate in the study of lncRNAs and exosomal lncRNAs in metastatic of cancer are included in this review.

Oral microbiome mediated inflammation, a potential inductor of vascular diseases: a comprehensive review

The dysbiosis of the oral microbiome and vascular translocation of the periodontopathic microorganism to peripheral blood can cause local and systemic extra-oral inflammation. Microorganisms associated with the subgingival biofilm are readily translocated to the peripheral circulation, generating bacteremia and endotoxemia, increasing the inflammation in the vascular endothelium and resulting in endothelial dysfunction. This review aimed to demonstrate how the dysbiosis of the oral microbiome and the translocation of oral pathogen-induced inflammation to peripheral blood may be linked to cardiovascular diseases (CVDs). The dysbiosis of the oral microbiome can regulate blood pressure and activate endothelial dysfunction. Similarly, the passage of periodontal microorganisms into the peripheral circulation and their virulence factors have been associated with a vascular compartment with a great capacity to activate endothelial cells, monocytes, macrophages, and plaquettes and increase interleukin and chemokine secretion, as well as oxidative stress. This inflammatory process is related to atherosclerosis, hypertension, thrombosis, and stroke. Therefore, oral diseases could be involved in CVDs via inflammation. The preclinic and clinical evidence suggests that periodontal disease increases the proinflammatory markers associated with endothelial dysfunction. Likewise, the evidence from clinical studies of periodontal treatment in the long term evidenced the reduction of these markers and improved overall health in patients with CVDs.

Cellular and Molecular Mechanisms of the Tumor Stroma in Colorectal Cancer: Insights into Disease Progression and Therapeutic Targets

Colorectal cancer (CRC) is a major health burden worldwide and is the third most common type of cancer. The early detection and diagnosis of CRC is critical to improve patient outcomes. This review explores the intricate interplay between the tumor microenvironment, stromal interactions, and the progression and metastasis of colorectal cancer. The review begins by assessing the gut microbiome's influence on CRC development, emphasizing its association with gut-associated lymphoid tissue (GALT). The role of the Wnt signaling pathway in CRC tumor stroma is scrutinized, elucidating its impact on disease progression. Tumor budding, its effect on tumor stroma, and the implications for patient prognosis are investigated. The review also identifies conserved oncogenic signatures (COS) within CRC stroma and explores their potential as therapeutic targets. Lastly, the seed and soil hypothesis is employed to contextualize metastasis, accentuating the significance of both tumor cells and the surrounding stroma in metastatic propensity. This review highlights the intricate interdependence between CRC cells and their microenvironment, providing valuable insights into prospective therapeutic approaches targeting tumor-stroma interactions.

Salivary and fecal microbiota: potential new biomarkers for early screening of colorectal polyps

Objective

Gut microbiota plays an important role in colorectal cancer (CRC) pathogenesis through microbes and their metabolites, while oral pathogens are the major components of CRC-associated microbes. Multiple studies have identified gut and fecal microbiome-derived biomarkers for precursors lesions of CRC detection. However, few studies have used salivary samples to predict colorectal polyps. Therefore, in order to find new noninvasive colorectal polyp biomarkers, we searched into the differences in fecal and salivary microbiota between patients with colorectal polyps and healthy controls.

Methods

In this case-control study, we collected salivary and fecal samples from 33 patients with colorectal polyps (CP) and 22 healthy controls (HC) between May 2021 and November 2022. All samples were sequenced using full-length 16S rRNA sequencing and compared with the Nucleotide Sequence Database. The salivary and fecal microbiota signature of colorectal polyps was established by alpha and beta diversity, Linear discriminant analysis Effect Size (LEfSe) and random forest model analysis. In addition, the possibility of microbiota in identifying colorectal polyps was assessed by Receiver Operating Characteristic Curve (ROC).

Results

In comparison to the HC group, the CP group's microbial diversity increased in saliva and decreased in feces (p < 0.05), but there was no significantly difference in microbiota richness (p > 0.05). The principal coordinate analysis revealed significant differences in β-diversity of salivary and fecal microbiota between the CP and HC groups. Moreover, LEfSe analysis at the species level identified Porphyromonas gingivalis, Fusobacterium nucleatum, Leptotrichia wadei, Prevotella intermedia, and Megasphaera micronuciformis as the major contributors to the salivary microbiota, and Ruminococcus gnavus, Bacteroides ovatus, Parabacteroides distasonis, Citrobacter freundii, and Clostridium symbiosum to the fecal microbiota of patients with polyps. Salivary and fecal bacterial biomarkers showed Area Under ROC Curve of 0.8167 and 0.8051, respectively, which determined the potential of diagnostic markers in distinguishing patients with colorectal polyps from controls, and it increased to 0.8217 when salivary and fecal biomarkers were combined.

Conclusion

The composition and diversity of the salivary and fecal microbiota were significantly different in colorectal polyp patients compared to healthy controls, with an increased abundance of harmful bacteria and a decreased abundance of beneficial bacteria. A promising non-invasive tool for the detection of colorectal polyps can be provided by potential biomarkers based on the microbiota of the saliva and feces.

A mucin-regulated adhesin determines the spatial organization and inflammatory character of a bacterial symbiont in the vertebrate gut

In a healthy gut, microbes are often aggregated with host mucus, yet the molecular basis for this organization and its impact on intestinal health are unclear. Mucus is a viscous physical barrier separating resident microbes from epithelia, but it also provides glycan cues that regulate microbial behaviors. Here, we describe a mucin-sensing pathway in an Aeromonas symbiont of zebrafish, Aer01. In response to the mucin-associated glycan N-acetylglucosamine, a sensor kinase regulates the expression of an aggregation-promoting adhesin we named MbpA. Upon MbpA disruption, Aer01 colonizes to normal levels but is largely planktonic and more pro-inflammatory. Increasing cell surface MbpA rescues these traits. MbpA-like adhesins are common in human-associated bacteria, and the expression of an Akkermansia muciniphila MbpA-like adhesin in MbpA-deficient Aer01 restores lumenal aggregation and reverses its pro-inflammatory character. Our work demonstrates how resident bacteria use mucin glycans to modulate behaviors congruent with host health.

Type IV pili facilitated natural competence in Fusobacterium nucleatum

OBJECTIVES

Many bacterial species naturally take up DNA from their surroundings and recombine it into their chromosome through homologous gene transfer (HGT) to aid in survival and gain advantageous functions. Herein we present the first characterization of Type IV pili facilitated natural competence in Fusobacterium nucleatum, which is a Gram-negative, anaerobic bacterium that participates in a range of infections and diseases including periodontitis, preterm birth, and cancer.

METHODS

Here we used bioinformatics on multiple Fusobacterium species, as well as molecular genetics to characterize natural competence in strain F. nucleatum subsp. nucleatum ATCC 23726.

RESULTS

We bioinformatically identified components of the Type IV conjugal pilus machinery and show this is a conserved system within the Fusobacterium genus. We next validate Type IV pili in natural competence in F. nucleatum ATCC 23726 and show that gene deletions in key components of pilus deployment (pilQ) and cytoplasmic DNA import (comEC) abolish DNA uptake and chromosomal incorporation. We next show that natural competence may require native F. nucleatum DNA methylation to bypass restriction modification systems and allow subsequent genomic homologous recombination.

CONCLUSIONS

In summary, this proof of principle study provides the first characterization of natural competence in Fusobacterium nucleatum and highlights the potential to exploit this DNA import mechanism as a genetic tool to characterize virulence mechanisms of an opportunistic oral pathogen.

Increased Fusobacterium tumoural abundance affects immunogenicity in mucinous colorectal cancer and may be associated with improved clinical outcome

There is currently an urgent need to identify factors predictive of immunogenicity in colorectal cancer (CRC). Mucinous CRC is a distinct histological subtype of CRC, associated with a poor response to chemotherapy. Recent evidence suggests the commensal facultative anaerobe Fusobacterium may be especially prevalent in mucinous CRC. The objectives of this study were to assess the association of Fusobacterium abundance with immune cell composition and prognosis in mucinous CRC. Our study included two independent colorectal cancer patient cohorts, The Cancer Genome Atlas (TCGA) cohort, and a cohort of rectal cancers from the Beaumont RCSI Cancer Centre (BRCC). Multiplexed immunofluorescence staining of a tumour microarray (TMA) from the BRCC cohort was undertaken using Cell DIVE technology. Our cohorts included 87 cases (13.3%) of mucinous and 565 cases (86.7%) of non-mucinous CRC. Mucinous CRC in the TCGA dataset was associated with an increased proportion of CD8 + lymphocytes (p = 0.018), regulatory T-cells (p = 0.001) and M2 macrophages (p = 0.001). In the BRCC cohort, mucinous RC was associated with enhanced CD8 + lymphocyte (p = 0.022), regulatory T-cell (p = 0.047), and B-cell (p = 0.025) counts. High Fusobacterium abundance was associated with an increased proportion of CD4 + lymphocytes (p = 0.031) and M1 macrophages (p = 0.006), whilst M2 macrophages (p = 0.043) were under-represented in this cohort. Patients with increased Fusobacterium relative abundance in our mucinous CRC TCGA cohort tended to have better clinical outcomes (DSS: likelihood ratio p = 0.04, logrank p = 0.052). Fusobacterium abundance may be associated with improved outcomes in mucinous CRC, possibly due to a modulatory effect on the host immune response. KEY MESSAGES: • Increased Fusobacterium relative abundance was not found to be associated with microsatellite instability in mucinous CRC. • Increased Fusobacterium relative abundance was associated with an M2/M1 macrophage switch, which is especially significant in mucinous CRC, where M2 macrophages are overexpressed. • Increased Fusobacterium relative abundance was associated with a significant improvement in disease specific survival in mucinous CRC. • Our findings were validated at a protein level within our own in house mucinous and non-mucinous rectal cancer cohorts.

Periodontal Health and Disease in the Context of Systemic Diseases

During recent years, considerable progress has been made in understanding the etiopathogenesis of periodontitis in its various forms and their interactions with the host. Furthermore, a number of reports have highlighted the importance of oral health and disease in systemic conditions, especially cardiovascular diseases and diabetes. In this regard, research has attempted to explain the role of periodontitis in promoting alteration in distant sites and organs. Recently, DNA sequencing studies have revealed how oral infections can occur in distant sites such as the colon, reproductive tissues, metabolic diseases, and atheromas. The objective of this review is to describe and update the emerging evidence and knowledge regarding the association between periodontitis and systemic disease and to analyse the evidence that has reported periodontitis as a risk factor for the development of various forms of systemic diseases in order to provide a better understanding of the possible shared etiopathogenetic pathways between periodontitis and the different forms of systemic diseases.

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.