Association of autophagy status with amount of Fusobacterium nucleatum in colorectal cancer

Periodontopathogen-Related Cell Autophagy-A Double-Edged Sword

The periodontium is a highly organized ecosystem, and the imbalance between oral microorganisms and host defense leads to periodontal diseases. The periodontal pathogens, mainly Gram-negative anaerobic bacteria, colonize the periodontal niches or enter the blood circulation, resulting in periodontal tissue destruction and distal organ damage. This phenomenon links periodontitis with various systemic conditions, including cardiovascular diseases, malignant tumors, steatohepatitis, and Alzheimer's disease. Autophagy is an evolutionarily conserved cellular self-degradation process essential for eliminating internalized pathogens. Nowadays, increasing studies have been carried out in cells derived from periodontal tissues, immune system, and distant organs to investigate the relationship between periodontal pathogen infection and autophagy-related activities. On one hand, as a vital part of innate and adaptive immunity, autophagy actively participates in host resistance to periodontal bacterial infection. On the other, certain periodontal pathogens exploit autophagic vesicles or pathways to evade immune surveillance, therefore achieving survival within host cells. This review provides an overview of the autophagy process and focuses on periodontopathogen-related autophagy and their involvements in cells of different tissue origins, so as to comprehensively understand the role of autophagy in the occurrence and development of periodontal diseases and various periodontitis-associated systemic illnesses.

Application Value of Antimicrobial Peptides in Gastrointestinal Tumors

Gastrointestinal cancer is a common clinical malignant tumor disease that seriously endangers human health and lacks effective treatment methods. As part of the innate immune defense of many organisms, antimicrobial peptides not only have broad-spectrum antibacterial activity but also can specifically kill tumor cells. The positive charge of antimicrobial peptides under neutral conditions determines their high selectivity to tumor cells. In addition, antimicrobial peptides also have unique anticancer mechanisms, such as inducing apoptosis, autophagy, cell cycle arrest, membrane destruction, and inhibition of metastasis, which highlights the low drug resistance and high specificity of antimicrobial peptides. In this review, we summarize the related studies on antimicrobial peptides in the treatment of digestive tract tumors, mainly oral cancer, esophageal cancer, gastric cancer, liver cancer, pancreatic cancer, and colorectal cancer. This paper describes the therapeutic advantages of antimicrobial peptides due to their unique anticancer mechanisms. The length, net charge, and secondary structure of antimicrobial peptides can be modified by design or modification to further enhance their anticancer effects. In summary, as an emerging cancer treatment drug, antimicrobial peptides need to be further studied to realize their application in gastrointestinal cancer diseases.

Fusobacterium nucleatum Load Correlates with KRAS Mutation and Sessile Serrated Pathogenesis in Colorectal Adenocarcinoma

Fusobacterium nucleatum (Fn) has been frequently detected in colorectal cancer. A high load of Fn has been associated with subtypes of colorectal cancers, located in the proximal colon, exhibiting microsatellite instability-high (MSI-H), MLH1 promoter hypermethylation, the CpG island hypermethylation phenotype-high, or BRAF mutation in some studies. Although these features characterize the sessile serrated pathway (SSP) of colon cancers, other studies have shown that Fn infection is associated with KRAS mutations mainly characteristic of non-serrated neoplasia. It is also not clear at what point the association of Fn infection with these genomic alterations is established during colorectal carcinogenesis. Here we show that MSI-H, MLH1 hypermethylation, BRAF mutation or KRAS mutations were independently associated with Fn infection in colorectal cancer. On the other hand, increasing Fn copy number in tissues was associated with increased probability to exhibit MSI-H, MLH1 hypermethylation or BRAF mutations but not KRAS mutations in colorectal cancer. We also show that Fn load was significantly less than that of colorectal cancer and no association was detected between BRAF/KRAS mutations or MLH1 hypermethylation and Fn infection in adenomas. Our combined data suggest that increasing loads of Fn during and/or after adenomacarcinoma transition might promote SSP but not KRAS-driven colorectal carcinogenesis. Alternatively, Fn preferentially colonizes colorectal cancers with SSP and KRAS mutations but can expand more in colorectal cancers with SSP.

SIGNIFICANCE

The authors demonstrated that Fn is enriched in colorectal cancers exhibiting the SSP phenotype, and in colorectal cancers carrying KRAS mutations. Fn infection should be considered as a candidate risk factor specific to colorectal cancers with the SSP phenotype and with KRAS mutations.

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

Objectives

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

Methods

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

Results

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

Conclusions

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

MicroRNA-31 induced by Fusobacterium nucleatum infection promotes colorectal cancer tumorigenesis

Persistent Fusobacterium nucleatum infection is associated with the development of human colorectal cancer (CRC) and promotes tumorigenicity, but the underlying mechanisms remain unclear. Here, we reported that F. nucleatum promoted the tumorigenicity of CRC, which was associated with F. nucleatum-induced microRNA-31 (miR-31) expression in CRC tissues and cells. F. nucleatum infection inhibited autophagic flux by miR-31 through inhibiting syntaxin-12 (STX12) and was associated with the increased intracellular survival of F. nucleatum. Overexpression of miR-31 in CRC cells promoted their tumorigenicity by targeting eukaryotic initiation factor 4F-binding protein 1/2 (eIF4EBP1/2), whereas miR-31 knockout mice were resistant to the formation of colorectal tumors. In conclusion, F. nucleatum, miR-31, and STX12 form a closed loop in the autophagy pathway, and continuous F. nucleatum-induced miR-31 expression promotes the tumorigenicity of CRC cells by targeting eIF4EBP1/2. These findings reveal miR-31 as a potential diagnostic biomarker and therapeutic target in CRC patients with F. nucleatum infection.

Long noncoding RNA SNHG15: A promising target in human cancers

As oncogenes or tumor suppressor genes, lncRNAs played an important role in tumorigenesis and the progression of human cancers. The lncRNA SNHG15 has recently been revealed to be dysregulated in malignant tumors, suggesting the aberrant expression of which contributes to clinical features and regulates various oncogenic processes. We have selected extensive literature focused on SNHG15 from electronic databases, including studies relevant to its clinical significance and the critical events in cancer-related processes such as cell proliferation, apoptosis, autophagy, metastasis, and drug resistance. This review summarized the current understanding of SNHG15 in cancer, mainly focusing on the pathological features, known biological functions, and underlying molecular mechanisms. Furthermore, SNHG15 has been well-documented to be an effective diagnostic and prognostic marker for tumors, offering novel therapeutic interventions in specific subsets of cancer cells.

Autophagy and the Insulin-like Growth Factor (IGF) System in Colonic Cells: Implications for Colorectal Neoplasia

Colorectal cancer (CRC) is one of the most common human malignancies worldwide. Along with apoptosis and inflammation, autophagy is one of three important mechanisms in CRC. The presence of autophagy/mitophagy in most normal mature intestinal epithelial cells has been confirmed, where it has mainly protective functions against reactive oxygen species (ROS)-induced DNA and protein damage. Autophagy regulates cell proliferation, metabolism, differentiation, secretion of mucins and/or anti-microbial peptides. Abnormal autophagy in intestinal epithelial cells leads to dysbiosis, a decline in local immunity and a decrease in cell secretory function. The insulin-like growth factor (IGF) signaling pathway plays an important role in colorectal carcinogenesis. This is evidenced by the biological activities of IGFs (IGF-1 and IGF-2), IGF-1 receptor type 1 (IGF-1R) and IGF-binding proteins (IGF BPs), which have been reported to regulate cell survival, proliferation, differentiation and apoptosis. Defects in autophagy are found in patients with metabolic syndrome (MetS), inflammatory bowel diseases (IBD) and CRC. In neoplastic cells, the IGF system modulates the autophagy process bidirectionally. In the current era of improving CRC therapies, it seems important to investigate the exact mechanisms not only of apoptosis, but also of autophagy in different populations of tumor microenvironment (TME) cells. The role of the IGF system in autophagy in normal as well as transformed colorectal cells still seems poorly understood. Hence, the aim of the review was to summarize the latest knowledge on the role of the IGF system in the molecular mechanisms of autophagy in the normal colon mucosa and in CRC, taking into account the cellular heterogeneity of the colonic and rectal epithelium.

Optimized Antimicrobial Peptide Jelleine-I Derivative Br-J-I Inhibits Fusobacterium Nucleatum to Suppress Colorectal Cancer Progression

Colorectal cancer (CRC) is a major health burden worldwide due to its high morbidity, mortality, and complex etiology. Fusobacterium nucleatum (Fn), a Gram-negative anaerobe found in 30% of CRC patients, promotes CRC carcinogenesis, metastasis, and chemoresistance. Effective antimicrobial treatment is an unmet need for the rising CRC burden. Antimicrobial peptides (AMPs) represent a new class of antimicrobial drugs. In our previous study, we did the structure-activity study of Jelleine-I (J-I) and identified several halogenated J-I derivatives Cl-J-I, Br-J-I, and I-J-I. To determine whether those J-I derivatives can be a new therapy for bacterial-associated CRC, here we tested the antibacterial activities of these AMPs against Fn and their effects on CRC development. We found that Br-J-I showed the highest anti-Fn activity and Br-J-I may target membrane-associated FadA for Fn membrane disruption. More importantly, Fn promoted the growth of CRC cells-derived xenograft tumors. Br-J-I suppressed Fn load, colon inflammation, and Fn-induced CRC growth. Of note, Br-J-I induced better anti-CRC effects than common antibiotic metronidazole and Br-J-I sensitized the cancer-killing effect of chemotherapy drug 5-fluorouracil. These results suggest that Br-J-I could be considered as an adjunctive agent for CRC treatment and AMPs-based combination treatment is a new strategy for CRC in the future.

Clinical application of autophagy proteins as prognostic biomarkers in colorectal cancer: a meta-analysis

Aim: To evaluate the prognostic value of autophagy proteins in colorectal cancer (CRC). Methods: Six potential autophagy proteins were analyzed (Beclin-1, LC3A, LC3B, ULK1, ATG10 and p62). Hazard ratios (HRs) and 95% CIs for overall survival (OS) of CRC patients were calculated. Results: A total of 20 studies were included. High expression of LC3B and p62 was associated with favorable OS (HR: 0.56, 95% CI: 0.40-0.80; HR: 0.76, 95% CI: 0.61-0.96), whereas high expression of Beclin-1 (HR: 1.47, 95% CI: 1.05-2.06) and ULK1 (HR: 1.92. 95% CI: 1.05-3.53) might predict worse OS in CRC patients. Conclusion: Beclin-1, LC3B and p62 might act as promising prognostic biomarkers for CRC. High LC3 and p62 expression can be reliable tools for metastasis prediction.

A systematic review of microbial markers for risk prediction of colorectal neoplasia

BACKGROUND

Substantial evidence indicates that dysbiosis of the gut microbial community is associated with colorectal neoplasia. This review aims to systematically summarise the microbial markers associated with colorectal neoplasia and to assess their predictive performance.

METHODS

A comprehensive literature search of MEDLINE and EMBASE databases was performed to identify eligible studies. Observational studies exploring the associations between microbial biomarkers and colorectal neoplasia were included. We also included prediction studies that constructed models using microbial markers to predict CRC and adenomas. Risk of bias for included observational and prediction studies was assessed.

RESULTS

Forty-five studies were included to assess the associations between microbial markers and colorectal neoplasia. Nine faecal microbiotas (i.e., Fusobacterium, Enterococcus, Porphyromonas, Salmonella, Pseudomonas, Peptostreptococcus, Actinomyces, Bifidobacterium and Roseburia), two oral pathogens (i.e., Treponema denticola and Prevotella intermedia) and serum antibody levels response to Streptococcus gallolyticus subspecies gallolyticus were found to be consistently associated with colorectal neoplasia. Thirty studies reported prediction models using microbial markers, and 83.3% of these models had acceptable-to-good discrimination (AUROC > 0.75). The results of predictive performance were promising, but most of the studies were limited to small number of cases (range: 9-485 cases) and lack of independent external validation (76.7%).

CONCLUSIONS

This review provides insight into the evidence supporting the association between different types of microbial species and their predictive value for colorectal neoplasia. Prediction models developed from case-control studies require further external validation in high-quality prospective studies. Further studies should assess the feasibility and impact of incorporating microbial biomarkers in CRC screening programme.

The association between Fusobacterium nucleatum and cancer colorectal: A systematic review and meta-analysis

INTRODUCTION

The etiological factors of colorectal cancer (CRC) are not precisely known, although genetic and environmental factors have been implicated. A possible association with Fusobacterium nucleatum may provide opportunities for an early diagnosis.

OBJECTIVE

To review studies that address the association between F. nucleatum and CRC.

METHODS

The MEDLINE PubMed database was searched using the terms «colorectal cancer» and "Fusobacterium nucleatum", retrieving publications published up to January 1 2020. Stata software was used for a meta-analysis.

RESULTS

The systematic review included 57 articles. Meta-analysis results indicated a more frequent presence of F. nucleatum in CRC tumour tissue samples in comparison to control samples of healthy tissue, with an odds ratio of 4.558 (95% CI: 3.312-6.272), and in comparison, to control samples of colorectal adenomas, with an odds ratio of 3.244 (95 % CI: 2.359-4.462).

CONCLUSION

There is a more frequent resence of F. nucleatum in the CRC. However, further studies are needed to verify this relationship.

Gut Dysbiosis and Intestinal Barrier Dysfunction: Potential Explanation for Early-Onset Colorectal Cancer

Colorectal cancer (CRC) is a heterogeneous disease that commonly affects individuals aged more than 50 years old globally. Regular colorectal screening, which is recommended for individuals aged 50 and above, has decreased the number of cancer death toll over the years. However, CRC incidence has increased among younger population (below 50 years old). Environmental factors, such as smoking, dietary factor, urbanization, sedentary lifestyle, and obesity, may contribute to the rising trend of early-onset colorectal cancer (EOCRC) because of the lack of genetic susceptibility. Research has focused on the role of gut microbiota and its interaction with epithelial barrier genes in sporadic CRC. Population with increased consumption of grain and vegetables showed high abundance of Prevotella, which reduces the risk of CRC. Microbes, such as Fusobacterium nucleatum, Bacteroides fragilis and Escherichia coli deteriorate in the intestinal barrier, which leads to the infiltration of inflammatory mediators and chemokines. Gut dysbiosis may also occur following inflammation as clearly observed in animal model. Both gut dysbiosis pre- or post-inflammatory process may cause major alteration in the morphology and functional properties of the gut tissue and explain the pathological outcome of EOCRC. The precise mechanism of disease progression from an early stage until cancer establishment is not fully understood. We hypothesized that gut dysbiosis, which may be influenced by environmental factors, may induce changes in the genome, metabolome, and immunome that could destruct the intestinal barrier function. Also, the possible underlying inflammation may give impact microbial community leading to disruption of physical and functional role of intestinal barrier. This review explains the potential role of the interaction among host factors, gut microenvironment, and gut microbiota, which may provide an answer to EOCRC.

Associations of Porphyromonas gingivalis Infection and Low Beclin1 Expression With Clinicopathological Parameters and Survival of Esophageal Squamous Cell Carcinoma Patients

Purpose: The present study focused on exploring the associations of Porphyromonas gingivalis (P. gingivalis) infection and low Beclin1 expression with clinicopathological parameters and survival of esophageal squamous cell carcinoma (ESCC) patients, so as to illustrate its clinical significance and prognostic value. Methods: Immunohistochemistry (IHC) was used to detect P. gingivalis infection status and Beclin1 expression in 370 ESCC patients. The chi-square test was adopted to illustrate the relationship between categorical variables, and Cohen's kappa coefficient was used for correlation analysis. Kaplan-Meier survival curves with the log-rank test were used to analyse the correlation of P. gingivalis infection and low Beclin1 expression with survival time. The effects of P. gingivalis infection and Beclin1 downregulation on the proliferation, migration and antiapoptotic abilities of ESCC cells in vitro were detected by Cell Counting Kit-8, wound healing and flow cytometry assays. For P. gingivalis infection of ESCC cells, cell culture medium was replaced with antibiotic-free medium when the density of ESCC cells was 70-80%, cells were inoculated with P. gingivalis at a multiplicity of infection (MOI) of 10. Result: P. gingivalis infection was negatively correlated with Beclin1 expression in ESCC tissues, and P. gingivalis infection and low Beclin1 expression were associated with differentiation status, tumor invasion depth, lymph node metastasis, clinical stage and prognosis in ESCC patients. In vitro experiments confirmed that P. gingivalis infection and Beclin1 downregulation potentiate the proliferation, migration and antiapoptotic abilities of ESCC cells (KYSE150 and KYSE30). Our results provide evidence that P. gingivalis infection and low Beclin1 expression were associated with the development and progression of ESCC. Conclusion: Long-term smoking and alcohol consumption causes poor oral and esophageal microenvironments and ESCC patients with these features were more susceptible to P. gingivalis infection and persistent colonization, and exhibited lower Beclin1 expression, worse prognosis and more advanced clinicopathological features. Our findings indicate that effectively eliminating P. gingivalis colonization and restoring Beclin1 expression in ESCC patients may contribute to preventation and targeted treatment, and yield new insights into the aetiological research on ESCC.

Association of PIK3CA mutation and PTEN loss with expression of CD274 (PD-L1) in colorectal carcinoma

Immunotherapy targeting the CD274 (PD-L1)/PDCD1 (PD-1) immune checkpoint axis has emerged as a promising treatment strategy for various cancers. Experimental evidence suggests that phosphatidylinositol-4,5-bisphosphonate 3-kinase (PI3K) signaling may upregulate CD274 expression. Thus, we hypothesized that PIK3CA mutation, PTEN loss, or their combined status might be associated with CD274 overexpression in colorectal carcinoma. We assessed tumor CD274 and PTEN expression by immunohistochemistry and assessed PIK3CA mutation by pyrosequencing in 753 patients among 4,465 incident rectal and colon cancer cases that had occurred in two U.S.-wide prospective cohort studies. To adjust for potential confounders and selection bias due to tissue availability, inverse probability weighted multivariable ordinal logistic regression analyses used the 4,465 cases and tumoral data including microsatellite instability, CpG island methylator phenotype, KRAS and BRAF mutations. PIK3CA mutation and loss of PTEN expression were detected in 111 of 753 cases (15%) and 342 of 585 cases (58%), respectively. Tumor CD274 expression was negative in 306 (41%), low in 195 (26%), and high in 252 (33%) of 753 cases. PTEN loss was associated with CD274 overexpression [multivariable odds ratio (OR) 1.83; 95% confidence interval (CI), 1.22–2.75; P = .004]. PIK3CA mutation was statistically-insignificantly (P = .036 with the stringent alpha level of 0.005) associated with CD274 overexpression (multivariable OR, 1.54; 95% CI, 1.03–2.31). PIK3CA-mutated PTEN-lost tumors (n = 33) showed higher prevalence of CD274-positivity (82%) than PIK3CA-wild-type PTEN-lost tumors (n = 204; 70% CD274-positivity) and PTEN-expressed tumors (n = 147; 50% CD274-positivity) (P = .003). Our findings support the role of PI3K signaling in the CD274/PDCD1 pathway.

Tying Small Changes to Large Outcomes: The Cautious Promise in Incorporating the Microbiome into Immunotherapy

The role of the microbiome in immunology is a rapidly burgeoning topic of study. Given the increasing use of immune checkpoint inhibitor (ICI) therapy in cancers, along with the recognition that carcinogenesis has been linked to dysregulations of the immune system, much attention is now directed at potentiation of ICI efficacy, as well as minimizing the incidence of treatment-associated immune-related adverse events (irAEs). We provide an overview of the major research establishing links between the microbiome to tumorigenesis, chemotherapy and radiation potentiation, and ICI efficacy and irAE development.

Correlation of autophagy-related genes for predicting clinical prognosis in colorectal cancer

Aim: Autophagy plays a controversial role in cancer. The role of autophagy-related genes (ARGs) in colorectal cancer (CRC) was evaluated based on publicly available data from The Cancer Genome Atlas and the Human Autophagy Database. Materials & methods: After collecting CRC-related transcript and clinical data and a list of ARGs from public databases, the Wilcoxon test was used to identify the differentially expressed ARGs between CRC and paired normal tissues. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses were used to identify the major biological properties and pathways associated with these genes. Univariate Cox regression was used to identify the prognosis-associated ARGs, and a forest plot was used to visualize the results. Kaplan-Meier analysis of the 5-year survival rate was performed. Univariate and multivariate Cox analyses were used to verify the impact of the prognosis-associated ARGs. Results: A total of 36 differentially expressed genes (16 upregulated and 20 downregulated in CRC) were obtained from among 206 ARGs. There were 53 enriched pathways, including the p53 signaling pathway, platinum drug resistance, apoptosis, EGFR tyrosine kinase inhibitor resistance and ErbB signaling pathway (p- and q-values <0.05). Kaplan-Meier analysis showed that the 5-year survival rate was 46.0% (95% CI: 0.335-0.631) and 76.0% (95% CI: 0.651-0.886) in the high- and low-risk groups, respectively. The high-risk patients had worse survival probability (p = 6.256 × 10-5). Independent-samples t-tests revealed that MAP1LC3C expression was higher in patients aged ≤65 than >65 (p = 0.022); RAB7A expression was higher in patients aged ≤65 than >65 (p = 7.31 × 10-4), higher in M1 than M0 (p = 0.042), higher in N1-3 than N0 (p = 0.002) and higher in stage III and IV than I and II (p = 0.042); risk score was higher in N1-3 than N0 (p = 0.001) and in stage III and IV than I and II (p = 0.002); and WIPI2 expression was higher in M1 than M0 (p = 0.002), higher in N1-3 than N0 (p = 2.059 × 10-7) and higher in stage III and IV than I and II (p = 2.299 × 10-7). There were no differences in risk score between males and females (p = 0.593), T1-2 and T3-4 (p = 0.082) or M0 and M1 (p = 0.072). Univariate and multivariate Cox analyses showed that RAB7A was a lower-risk gene, while MAP1LC3C, WIPI2, DAPK1, ULK3 and PELP1 were high-risk genes. Conclusion: Certain ARGs are potential prognostic molecular markers of poor prognosis in CRC. Additionally, the p53 signaling pathway, platinum drug resistance, apoptosis, EGFR tyrosine kinase inhibitor resistance and ErbB signaling pathway may be critical pathways regulated by ARGs in CRC.

Association of Fusobacterium nucleatum with Specific T-cell Subsets in the Colorectal Carcinoma Microenvironment

PURPOSE

While evidence indicates that Fusobacterium nucleatum (F. nucleatum) may promote colorectal carcinogenesis through its suppressive effect on T-cell-mediated antitumor immunity, the specific T-cell subsets involved remain uncertain.

EXPERIMENTAL DESIGN

We measured F. nucleatum DNA within tumor tissue by quantitative PCR on 933 cases (including 128 F. nucleatum-positive cases) among 4,465 incident colorectal carcinoma cases in two prospective cohorts. Multiplex immunofluorescence combined with digital image analysis and machine learning algorithms for CD3, CD4, CD8, CD45RO (PTPRC isoform), and FOXP3 measured various T-cell subsets. We leveraged data on Bifidobacterium, microsatellite instability (MSI), tumor whole-exome sequencing, and M1/M2-type tumor-associated macrophages [TAM; by CD68, CD86, IRF5, MAF, and MRC1 (CD206) multimarker assay]. Using the 4,465 cancer cases and inverse probability weighting method to control for selection bias due to tissue availability, multivariable-adjusted logistic regression analysis assessed the association between F. nucleatum and T-cell subsets.

RESULTS

The amount of F. nucleatum was inversely associated with tumor stromal CD3+ lymphocytes [multivariable OR, 0.47; 95% confidence interval (CI), 0.28-0.79, for F. nucleatum-high vs. -negative category; P trend = 0.0004] and specifically stromal CD3+CD4+CD45RO+ cells (corresponding multivariable OR, 0.52; 95% CI, 0.32-0.85; P trend = 0.003). These relationships did not substantially differ by MSI status, neoantigen load, or exome-wide tumor mutational burden. F. nucleatum was not significantly associated with tumor intraepithelial T cells or with M1 or M2 TAMs.

CONCLUSIONS

The amount of tissue F. nucleatum is associated with lower density of stromal memory helper T cells. Our findings provide evidence for the interactive pathogenic roles of microbiota and specific immune cells.

Colibactin-Producing Escherichia coli Induce the Formation of Invasive Carcinomas in a Chronic Inflammation-Associated Mouse Model

Simple Summary

Changes in the composition of the intestinal flora have been reported in patients with colorectal cancer, the second leading cause of cancer death in the world, with an increase in so-called "harmful" bacteria. Among these, Escherichia coli producing colibactin, a toxin that causes DNA damage, has attracted the interest of many research groups. Here, we showed that infection of wild-type mice with a colibactin-producing E. coli (CoPEC) strain, isolated from a patient with colorectal cancer, combined with chronic inflammation induced the formation of invasive colonic tumors, i.e., tumors that spread beyond epithelial layer and grow into surrounding tissues. We also showed that autophagy, a cell defense process, is necessary to inhibit the tumorigenesis induced by CoPEC. Thus, this work highlights the role of CoPEC as a driver of colorectal cancer development, and suggests that targeting autophagy could be a promising strategy to inhibit the protumoral effects of these bacteria.

Abstract

Background: Escherichia coli producing the genotoxin colibactin (CoPEC or colibactin-producing E. coli) abnormally colonize the colonic mucosa of colorectal cancer (CRC) patients. We previously showed that deficiency of autophagy in intestinal epithelial cells (IECs) enhances CoPEC-induced colorectal carcinogenesis in Apc^Min/+ mice. Here, we tested if CoPEC trigger tumorigenesis in a mouse model lacking genetic susceptibility or the use of carcinogen. Methods: Mice with autophagy deficiency in IECs (Atg16l1^∆IEC) or wild-type mice (Atg16l1^flox/flox) were infected with the CoPEC 11G5 strain or the mutant 11G5∆clbQ incapable of producing colibactin and subjected to 12 cycles of DSS treatment to induce chronic colitis. Mouse colons were used for histological assessment, immunohistochemical and immunoblot analyses for DNA damage marker. Results: 11G5 or 11G5∆clbQ infection increased clinical and histological inflammation scores, and these were further enhanced by IEC-specific autophagy deficiency. 11G5 infection, but not 11G5∆clbQ infection, triggered the formation of invasive carcinomas, and this was further increased by autophagy deficiency. The increase in invasive carcinomas was correlated with enhanced DNA damage and independent of inflammation. Conclusions: CoPEC induce colorectal carcinogenesis in a CRC mouse model lacking genetic susceptibility and carcinogen. This work highlights the role of (i) CoPEC as a driver of CRC development, and (ii) autophagy in inhibiting the carcinogenic properties of CoPEC.

The dysbiosis signature of Fusobacterium nucleatum in colorectal cancer-cause or consequences? A systematic review

Colorectal cancer (CRC) is the third most common cause of cancer globally and the fourth attributable cause of mortality and morbidity due to cancer. An emerging factor contributing to CRC is the gut microbiota and the cellular changes associated with it. Further insights on this may help in the prevention, diagnosis and new therapeutic approaches to colorectal cancer. In most cases of CRC, genetic factors appear to contribute less to its aetiology than environmental and epigenetic factors; therefore, it may be important to investigate these environmental factors, their effects, and the mechanisms that may contribute to this cancer. The gut microbiota has recently been highlighted as a potential risk factor that may affect the structural components of the tumor microenvironment, as well as free radical and enzymatic metabolites directly, or indirectly. Many studies have reported changes in the gut microbiota of patients with colorectal cancer. What is controversial is whether the cancer is the cause or consequence of the change in the microbiota. There is strong evidence supporting both possibilities. The presence of Fusobacterium nucleatum in human colorectal specimens has been demonstrated by RNA-sequencing. F. nucleatum has been shown to express high levels of virulence factors such as FadA, Fap2 and MORN2 proteins. Our review of the published data suggest that F. nucleatum may be a prognostic biomarker of CRC risk, and hence raises the potential of antibiotic treatment of F. nucleatum for the prevention of CRC.

The association between Fusobacterium nucleatum and cancer colorectal: a systematic review and meta-analysis

INTRODUCTION

The etiological factors of colorectal cancer (CRC) are not precisely known, although genetic and environmental factors have been implicated. A possible association with Fusobacterium nucleatum may provide opportunities for an early diagnosis.

OBJECTIVE

To review studies that address the association between F. nucleatum and CRC.

METHODS

The MEDLINE PubMed database was searched using the terms «colorectal cancer» and «Fusobacterium nucleatum», retrieving publications published up to January 1 2020. Stata software was used for a meta-analysis.

RESULTS

The systematic review included 57 articles. Meta-analysis results indicated a more frequent presence of F. nucleatum in CRC tumor tissue samples in comparison to control samples of healthy tissue, with an odds ratio of 4.558 (95% CI: 3.312-6.272), and in comparison, to control samples of colorectal adenomas, with an odds ratio of 3.244 (95% CI: 2.359-4.462).

CONCLUSION

There is a more frequent presence of F. nucleatum in the CRC. However, further studies are needed to verify this relationship.

Microbes in Tumoral In Situ Tissues and in Tumorigenesis

Cancerous tumors are severe diseases affecting human health that have a complicated etiology and pathogenesis. Microbes have been considered to be related to the development and progression of numerous tumors through various pathogenic mechanisms in recent studies. Bacteria, which have so far remained the most studied microbes worldwide, have four major possible special pathogenic mechanisms (modulation of inflammation, immunity, DNA damage, and metabolism) that are related to carcinogenesis. This review aims to macroscopically summarize and verify the relationships between microbes and tumoral in situ tissues from cancers of four major different systems (urinary, respiratory, digestive, and reproductive); the abovementioned four microbial pathogenic mechanisms, as well as some synergistic pathogenic mechanisms, are also discussed. Once the etiologic role of microbes and their precise pathogenic mechanisms in carcinogenesis are known, the early prevention, diagnosis, and treatment of cancers would progress significantly.

The Role of Fusobacterium nucleatum in Colorectal Carcinogenesis

Colorectal cancer (CRC) is one of the most frequent and deadly neoplasms worldwide. Genetic factors, lifestyle habits, and inflammation are important risk factors associated with CRC development. In recent years, growing evidence has supporting the significant role of the intestinal microbiome in CRC carcinogenesis. Disturbances in the healthy microbial balance, known as dysbiosis, are frequently observed in these patients. Pathogenic microorganisms that induce intestinal dysbiosis have become an important target to determine the role of bacterial infection in tumorigenesis. Interestingly, the presence of different bacterial strains, such as Fusobacterium nucleatum, has been detected in tissue and stool from patients with CRC and associated with substantial clinical and molecular features, as well as with patient therapy response. Therefore, understanding how the presence and levels of F. nucleatumstrains in the gut affect the risk of CRC onset and progression may inform suitable candidates for interventions focused on modulation of this bacteria. Here we review new insights into the role of gut microbiota in CRC carcinogenesis and the clinical utility of using the detection of F. nucleatum in different settings such as screening, prognosis, and microbiota modulation as a means to prevent cancer, augment therapies, and reduce adverse effects of treatment.

The microbiome, genetics, and gastrointestinal neoplasms: the evolving field of molecular pathological epidemiology to analyze the tumor-immune-microbiome interaction

Metagenomic studies using next-generation sequencing technologies have revealed rich human intestinal microbiome, which likely influence host immunity and health conditions including cancer. Evidence indicates a biological link between altered microbiome and cancers in the digestive system. Escherichia coli and Bacteroides fragilis have been found to be enriched in colorectal mucosal tissues from patients with familial adenomatous polyposis that is caused by germline APC mutations. In addition, recent studies have found enrichment of certain oral bacteria, viruses, and fungi in tumor tissue and fecal specimens from patients with gastrointestinal cancer. An integrative approach is required to elucidate the role of microorganisms in the pathogenic process of gastrointestinal cancers, which develop through the accumulation of somatic genetic and epigenetic alterations in neoplastic cells, influenced by host genetic variations, immunity, microbiome, and environmental exposures. The transdisciplinary field of molecular pathological epidemiology (MPE) offers research frameworks to link germline genetics and environmental factors (including diet, lifestyle, and pharmacological factors) to pathologic phenotypes. The integration of microbiology into the MPE model (microbiology-MPE) can contribute to better understanding of the interactive role of environment, tumor cells, immune cells, and microbiome in various diseases. We review major clinical and experimental studies on the microbiome, and describe emerging evidence from the microbiology-MPE research in gastrointestinal cancers. Together with basic experimental research, this new research paradigm can help us to develop new prevention and treatment strategies for gastrointestinal cancers through targeting of the microbiome.

Metformin elicits antitumour effect by modulation of the gut microbiota and rescues Fusobacterium nucleatum-induced colorectal tumourigenesis

BACKGROUND

The effect of metformin on gut microbiota has been reported, but whether metformin can suppress colorectal cancer (CRC) by affecting gut microbiota composition and rescue F. nucleatum-induced tumourigenicity remains unclear.

METHODS

To identify microbiota associated with both CRC occurrence and metformin treatment, first, we reanalyzed the gut microbiome of our previous data on two human cohorts of normal and CRC individuals. Subsequently, we summarized microbiota altered by metformin from published literatures. Several taxa, including Fusobacterium, were associated with both CRC occurrence and metformin treatment. We investigated the effect of metformin on APCMin/+ mice given with or without F. nucleatum. 16S rRNA gene sequencing was performed.

FINDINGS

We summarized 131 genera altered by metformin from 18 published literatures. Five genera reported to be changed by metformin, including Bacteroides, Streptococcus, Achromobacter, Alistipes and Fusobacterium, were associated with CRC in both of our human cohorts. Metformin relieved the symptoms caused by F. nucleatum administration in APCMin/+ mice, and showed promise in suppressing intestinal tumour formation and rescuing F. nucleatum-induced tumourigenicity. Administration of F. nucleatum and/or metformin had effect on gut microbiome structure, composition and functions of APCMin/+ mice.

INTERPRETATION

This study pioneers in predicting critical CRC-associated taxa contributing to the antitumour effect of metformin, and correlating gut microbiome with the antitumour effect of metformin in experimental animals. We presented a basis for future investigations into metformin's potential effect on suppressing F. nucleatum-induced tumor formation in vivo.

FUNDING

This work was supported by grants from the National Natural Science Foundation of China (31701250).

Can the microbiota predict response to systemic cancer therapy, surgical outcomes, and survival? The answer is in the gut

INTRODUCTION

The gut microbiota seems to play a key role in tumorigenesis, across various hallmarks of cancer. Recent evidence suggests its potential use as a biomarker predicting drug response and adding prognostic information, generally in the context of immuno-oncology.

AREAS COVERED

In this review, we focus on the modulating effects of gut microbiota dysbiosis on various anticancer molecules used in practice, including cytotoxic and immune-modulating agents, primarily immune-checkpoint inhibitors (ICI). Pubmed/Medline-based literature search was conducted to find potential original studies that discuss gut microbiota as a prognostic and predictive biomarker for cancer therapy. We also looked at the US ClinicalTrials.gov website to find additional studies particularly ongoing human clinical trials.

EXPERT COMMENTARY

Sequencing of stool-derived materials and tissue samples from cancer patients and animal models has shown a significant enrichment of various bacteria such as Fusobacterium nucleatum and Bacteroides fragilis were associated with resistant disease and poorer outcomes. Gut microbiota was also found to be associated with surgical outcomes and seems to play a significant role in anastomotic leak (ATL) after surgery mainly by collagen breakdown. However, this research field is just at the beginning and the current findings are not yet ready to change clinical practice.