The Bacterial Microbiota of Gastrointestinal Cancers: Role in Cancer Pathogenesis and Therapeutic Perspectives

Gastrointestinal cancer resistance to treatment: the role of microbiota

The most common illnesses that adversely influence human health globally are gastrointestinal malignancies. The prevalence of gastrointestinal cancers (GICs) is relatively high, and the majority of patients receive ineffective care since they are discovered at an advanced stage of the disease. A major component of the human body is thought to be the microbiota of the gastrointestinal tract and the genes that make up the microbiome. The gut microbiota includes more than 3000 diverse species and billions of microbes. Each of them has benefits and drawbacks and been demonstrated to alter anticancer medication efficacy. Treatment of GIC with the help of the gut bacteria is effective while changes in the gut microbiome which is linked to resistance immunotherapy or chemotherapy. Despite significant studies and findings in this field, more research on the interactions between microbiota and response to treatment in GIC are needed to help researchers provide more effective therapeutic strategies with fewer treatment complication. In this review, we examine the effect of the human microbiota on anti-cancer management, including chemotherapy, immunotherapy, and radiotherapy.

Evidence for the presence of Borrelia burgdorferi in invasive breast cancer tissues

Borrelia burgdorferi, the causative agent of Lyme disease, has recently been demonstrated to infect and enhance the invasive properties of breast cancer cells, while also influencing the expression of inflammatory chemokines (CXCL8 and CXCL10). This study investigates the presence of B. burgdorferi in invasive breast cancer tissues using commercially available, FDA-approved breast cancer tissue microarrays consisting of 350 ductal, 32 lobular, and 22 intraductal invasive breast carcinomas, alongside 29 normal breast tissues. Employing fluorescent immunohistochemical staining and high-resolution imaging, the findings revealed that approximately 20% of invasive lobular and ductal carcinomas, followed by 14% of intraductal carcinomas, tested positive for B. burgdorferi, while all normal breast tissues tested negative. PCR analysis further confirmed the presence of B. burgdorferi DNA in breast cancer tissues. Moreover, 25% of B. burgdorferi-positive tissues exhibited expression of both chemokines, CXCL8 and CXCL10, which was not observed in B. burgdorferi-negative tissues. Analysis of available patient data, including age, indicated a correlation between older patients and B. burgdorferi-positive tissues. This study validates the presence of B. burgdorferi in invasive breast cancer tissues and highlights the involvement of key CXCL family members associated with inflammatory processes.

Effects of probiotic supplementation on the gut microbiota composition of adults: a systematic review of randomized clinical trials

Researchers have associated the therapeutic potential of probiotics with its ability to modulate gut microbiota, which is considered an "invisible organ" of the human body. The present study investigates the effects of probiotic supplementation on the gut microbiota composition of adults. The authors conducted a systematic review of the literature published in six different databases. The search followed PRISMA guidelines and aimed to identify randomized clinical trials on probiotic supplementation. All relevant publications indexed up to May 28, 2021, were retrieved. Then, the authors defined the inclusion and exclusion criteria. Two independent reviewers performed study screening, data extraction, and quality assessment. A total of 2,404 publications were retrieved, and eight studies met the eligibility criteria. The included randomized clinical trials were published between 2015 to 2020. The worldwide studies included adults aged from 18 to 79 years, most of whom were women (66.5%). Only one of the included studies observed significant effects on fecal microbiota composition in the relative abundance of Bacteroidetes and Firmicutes phyla in comparison with the placebo treatment. Overall, this systematic review could not draw consistent conclusions on the effects of probiotic supplementation on the gut microbiota composition of adults.

Bacterial Infections and Cancer: Exploring This Association And Its Implications for Cancer Patients

Bacterial infections are common in the etiology of human diseases owing to the ubiquity of bacteria. Such infections promote the development of periodontal disease, bacterial pneumonia, typhoid, acute gastroenteritis, and diarrhea in susceptible hosts. These diseases may be resolved using antibiotics/antimicrobial therapy in some hosts. However, other hosts may be unable to eliminate the bacteria, allowing them to persist for long durations and significantly increasing the carrier's risk of developing cancer over time. Indeed, infectious pathogens are modifiable cancer risk factors, and through this comprehensive review, we highlight the complex relationship between bacterial infections and the development of several cancer types. For this review, searches were performed on the PubMed, Embase, and Web of Science databases encompassing the entirety of 2022. Based on our investigation, we found several critical associations, of which some are causative: Porphyromonas gingivalis and Fusobacterium nucleatum are associated with periodontal disease, Salmonella spp., Clostridium perfringens, Escherichia coli, Campylobacter spp., and Shigella are associated with gastroenteritis. Helicobacter pylori infection is implicated in the etiology of gastric cancer, and persistent Chlamydia infections present a risk factor for the development of cervical carcinoma, especially in patients with the human papillomavirus (HPV) coinfection. Salmonella typhi infections are linked with gallbladder cancer, and Chlamydia pneumoniae infection is implicated in lung cancer, etc. This knowledge helps identify the adaptation strategies used by bacteria to evade antibiotic/antimicrobial therapy. The article also sheds light on the role of antibiotics in cancer treatment, the consequences of their use, and strategies for limiting antibiotic resistance. Finally, the dual role of bacteria in cancer development as well as in cancer therapy is briefly discussed, as this is an area that may help to facilitate the development of novel microbe-based therapeutics as a means of securing improved outcomes.

Association of Helicobacter pylori infection with survival outcomes in advanced gastric cancer patients treated with immune checkpoint inhibitors

Background

Accumulating evidence has revealed that the gut microbiota influences the effectiveness of immune checkpoint inhibitors (ICIs) in cancer patients. As a part of the human microbiome, Helicobacter pylori (H. pylori) was reported to be associated with reduced effectiveness of anti-PD1 immunotherapy in patients with non-small-cell lung cancer (NSCLC). Gastric cancer is more closely related to H. pylori, so we conducted a retrospective analysis to verify whether the association of H. pylori and effectiveness is applicable to advanced gastric cancer (AGC) patients.

Material and methods

AGC patients who had evidence of H. pylori and received anti-PD-1 antibodies were enrolled in the study. The differences in the disease control rate (DCR), overall survival (OS) and progression-free survival (PFS) between the H. pylori-positive group and the negative group were compared.

Results

A total of 77 patients were included in this study; 34 patients were H. pylori positive, and the prevalence of H. pylori infection was 44.2%. Compared with the H. pylori-negative group, patients in the H. pylori-positive group had a higher risk of nonclinical response to anti-PD-1 antibody, with an OR of 2.91 (95% CI: 1.13–7.50). Patients in the H. pylori-negative group had a longer OS and PFS than those in the positive group, with an estimated median OS of 17.5 months vs. 6.2 months (HR = 2.85, 95% CI: 1.70–4.78; P = 0.021) and a median PFS of 8.4 months vs. 2.7 months (HR = 3.11, 95% CI: 1.96–5.07, P = 0.008). Multivariate analysis indicated that H. pylori infection was independently associated with PFS (HR = 1.90, 95% CI: 1.10–3.30; P = 0.022).

Conclusion

Our study unveils for the first time that H. pylori infection is associated with the outcome of immunotherapy for AGC patients. Multicenter, large sample and prospective clinical studies are needed to verify the association.

The Regional Specificity of Mucosa-Associated Microbiota in Patients with Distal Colorectal Cancer

BACKGROUND/AIMS

Recent studies have demonstrated that the populations of several microbes are significantly increased in fecal samples from patients with colorectal cancer (CRC), suggesting their involvement in the development of CRC. The aim of this study was to identify microbes which are increased in distal CRCs and to identify the specific location of microbes increased in mucosal tissue around the tumor.

METHODS

Tissue specimens were collected from surgical resections of 28 distal CRCs. Five samples were collected from each specimen (location A: tumor, B: adjacent normal mucosa, C: normal mucosa 1 cm proximal to the tumor, D: normal mucosa 3 cm proximally, and E: normal mucosa 6 cm proximally). The microbiota in the sample were analyzed using 16S rRNA gene amplicon sequencing and the relative abundance (RA) of microbiota compared among the 5 locations.

RESULTS

At the genus level, the RA of Fusobacterium and Streptococcus at location A was the highest among the 5 locations, significantly different from that in location E. The dominant species of each genus was Fusobacterium nucleatum and Streptococcus anginosus. The RAs of these species gradually decreased from locations B to E with a statistically significant difference in F. nucleatum. The genus Peptostreptococcus also showed a similar trend, and the RA of Peptostreptococcus stomatis in location A was significantly associated with depth of tumor invasion and tumor size.

CONCLUSION

Although the clinical relevance is not clear yet, these results suggest that F. nucleatum, S. anginosus, and P. stomatis can spread to the adjacent normal tissues and may change the surrounding microenvironment to support the progression of CRC.

Urinary microbiome profile in men with genitourinary malignancies

Purpose

Recent advances in molecular biology technology have allowed identification of microbial communities in the urinary tract, and urinary microbiome is associated with various urological diseases. In this study, we aimed to characterize the urinary microbiome of genitourinary malignancies.

Materials and Methods

Metagenomic analysis of urinary DNA was performed in 85 patients including 30 with bladder cancer (BC), 27 with prostate cancer (PC), 12 with renal cancer (RC), and 16 with non-cancer (NC). 16S rRNA gene sequencing was conducted after amplification of the V3–V4 region.

Results

PC and RC had significantly lower Shannon index than BC, and beta diversity showed significantly different microbiome composition between four groups. We identified six genera of Cutibacterium, Peptoniphilus, Sphingomonas, Staphylococcus, Micrococcus, and Moraxella, which showed significantly different abundance between the four groups. When each of the malignancies were compared to NC at the species level, Micrococcus sp. was significantly increased in BC. We also identified 12 and five species with increased populations in PC and RC, respectively. Of these, Cutibacterium acnes, Cutibacterium granulosum, Peptoniphilus lacydonensis, and Tessaracoccus were significantly increased in both PC and RC.

Conclusions

Urinary microbiome composition was different depending on the xlink:type of genitourinary malignancies, and we identified bacteria that are significantly associated with each xlink:type of malignancy. Specifically, several bacterial species were associated both PC and RC, suggesting that PC and RC share a similar pathogenesis-related urinary microbiome.

Bacterial Extracellular Vesicles in Gastrointestinal Tract Cancer: An Unexplored Territory

Bacterial extracellular vesicles are membrane-enclosed, lipid bi-layer nanostructures that carry different classes of biomolecules, such as nucleic acids, lipids, proteins, and diverse types of small molecular metabolites, as their cargo. Almost all of the bacteria in the gut secrete extracellular vesicles to assist them in competition, survival, material exchange, host immune modulation, infection, and invasion. The role of gut microbiota in the development, progression, and pathogenesis of gastrointestinal tract (GIT) cancer has been well documented. However, the possible involvement of bacterial extracellular vesicles (bEVs) in GIT cancer pathophysiology has not been given due attention. Studies have illustrated the ability of bEVs to cross physiological barriers, selectively accumulate near tumor cells, and possibly alter the tumor microenvironment (TME). A systematic search of original published works related to bacterial extracellular vesicles on gastrointestinal cancer was performed for this review. The current systemic review outlines the possible impact of gut microbiota derived bEVs in GIT cancer in light of present-day understanding. The necessity of using advanced sequencing technologies, such as genetic, proteomic, and metabolomic investigation methodologies, to facilitate an understanding of the interrelationship between cancer-associated bacterial vesicles and gastrointestinal cancer is also emphasized. We further discuss the clinical and pharmaceutical potential of bEVs, along with future efforts needed to understand the mechanism of interaction of bEVs in GIT cancer pathogenesis.

Prospects and Challenges of the Study of Anti-Glycan Antibodies and Microbiota for the Monitoring of Gastrointestinal Cancer

Over the past decades, a large amount of data has been accumulated in various subfields of glycobiology. However, much clinically relevant data and many tools are still not widely used in medicine. Synthetic glycoconjugates with the known structure of glycans are an accurate tool for the study of glycan-binding proteins. We used polyacrylamide glycoconjugates (PGs) including PGs with tumour-associated glycans (TAGs) in immunoassays to assess the prognostic potential of the serum level of anti-glycan antibodies (AG Abs) in gastrointestinal cancer patients and found an association of AG Abs with survival. The specificity of affinity-isolated AG Abs was investigated using synthetic and natural glycoconjugates. AG Abs showed mainly a low specificity to tumour-associated and tumour-derived mucins; therefore, the protective role of the examined circulating AG Abs against cancer remains a challenge. In this review, our findings are analysed and discussed in the context of the contribution of bacteria to the AG Abs stimulus and cancer progression. Examples of the influence of pathogenic bacteria colonising tumours on cancer progression and patient survival through mechanisms of interaction with tumours and dysregulated immune response are considered. The possibilities and problems of the integrative study of AG Abs and the microbiome using high-performance technologies are discussed.

The role of the bacterial microbiome in the treatment of cancer

The human microbiome is defined as the microorganisms that reside in or on the human body, such as bacteria, viruses, fungi, and protozoa, and their genomes. The human microbiome participates in the modulation of human metabolism by influencing several intricate pathways. The association between specific bacteria or viruses and the efficacy of cancer treatments and the occurrence of treatment-related toxicity in cancer patients has been reported. However, the understanding of the interaction between the host microbiome and the cancer treatment response is limited, and the microbiome potentially plays a greater role in the treatment of cancer than reported to date. Here, we provide a thorough review of the potential role of the gut and locally resident bacterial microbiota in modulating responses to different cancer therapeutics to demonstrate the association between the gut or locally resident bacterial microbiota and cancer therapy. Probable mechanisms, such as metabolism, the immune response and the translocation of microbiome constituents, are discussed to promote future research into the association between the microbiome and other types of cancer. We conclude that the interaction between the host immune system and the microbiome may be the basis of the role of the microbiome in cancer therapies. Future research on the association between host immunity and the microbiome may improve the efficacy of several cancer treatments and provide insights into the cause of treatment-related side effects.

Association between infection with Campylobacter species, poor oral health and environmental risk factors on esophageal cancer: a hospital-based case-control study in Thailand

Background

Previous studies have shown the association between Campylobacter species infection and that environmental factors, poor oral hygiene in particular, are linked to an increased risk of esophageal cancer (EC). However, no study has reported on these factors in Thailand. Thus, this study’s objective was to evaluate the impact of the relationship between Campylobacter infection and environmental factors on EC incidence in the population of Thailand.

Methods

Data from a case–control study were collected from 105 newly diagnosed EC cases and 105 controls recruited from 2007 to 2017. Infection with Campylobacter spp. was detected in the formalin-fixed paraffin-embedded (FFPE) tissue of EC taken from gastroesophageal biopsy specimens obtained from the participants, and evaluated using TaqMan^® real-time PCR. Multivariable logistic regression was performed to calculate the odds ratios (ORs) and perform data analysis.

Results

Smoking, alcohol use, a family history of cancer, history of gastroesophageal reflux disease, poor oral hygiene and Campylobacter spp. infection were shown to be significant risk factors for EC (p  <  0.05). The combination of poor oral hygiene and infection with Campylobacter spp. constituted significant risk for EC (p  <  0.001). In addition, the risk of EC in subjects co-infected with C. rectus and C. concisus that practiced poor oral hygiene was even higher and was significant (ORadj  =  4.7; 95% CI 2.41–9.98; p  =  0.003).

Conclusions

In Thailand, the major risk factors for EC are smoking status, alcohol drinking, family history of cancer, GERD, poor oral hygiene and Campylobacter spp. infection. This study found Campylobacter spp. prevalence to be associated with EC and appears to be enhanced by poor oral hygiene, suggesting that a combination of poor oral hygiene and Campylobacter species infection may together act as an important etiological risk factor for EC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40001-021-00561-3.

Bacterial Infection and Non-Hodgkin B-Cell Lymphoma: Interactions between Pathogen, Host and the Tumor Environment

Non-Hodgkin B-cell lymphomas (NHL) are a heterogeneous group of lymphoid neoplasms with complex etiopathology, rich symptomatology, and a variety of clinical courses, therefore requiring different therapeutic approaches. The hypothesis that an infectious agent may initiate chronic inflammation and facilitate B lymphocyte transformation and lymphogenesis has been raised in recent years. Viruses, like EBV, HTLV-1, HIV, HCV and parasites, like Plasmodium falciparum, have been linked to the development of lymphomas. The association of chronic Helicobacter pylori (H. pylori) infection with mucosa-associated lymphoid tissue (MALT) lymphoma, Borrelia burgdorferi with cutaneous MALT lymphoma and Chlamydophila psittaci with ocular adnexal MALT lymphoma is well documented. Recent studies have indicated that other infectious agents may also be relevant in B-cell lymphogenesis such as Coxiella burnettii, Campylobacter jejuni, Achromobacter xylosoxidans, and Escherichia coli. The aim of the present review is to provide a summary of the current literature on infectious bacterial agents associated with B-cell NHL and to discuss its role in lymphogenesis, taking into account the interaction between infectious agents, host factors, and the tumor environment.

The pathogenic oral-gut-liver axis: new understandings and clinical implications

INTRODUCTION

Oral health is closely related to extra-oral disease status, as may be represented by the manifestations of gastrointestinal and liver diseases.

AREAS COVERED

This review focuses on the roles that the oral-gut or the oral-gut-liver axis play in the pathogenesis of inflammatory bowel disease, colorectal cancer, metabolic fatty liver disease, and nonalcoholic steatohepatitis. The discussion will begin with clinical data, including data from preclinical animal models, to elucidate mechanisms. We will also discuss ways to target oral dysbiosis and oral inflammation to treat gastrointestinal and liver diseases.

EXPERT OPINION

Several studies have demonstrated that oral pathobionts can translocate to the gastrointestinal tract where they contribute to inflammation and tumorigenesis. Furthermore, oral bacteria that migrate to the gastrointestinal tract can disseminate to the liver and cause hepatic disease. Thus, oral bacteria that ectopically colonize the intestine may serve as biomarkers for gastrointestinal and liver diseases. Also, understanding the characteristics of the oral-gut and oral-gut-liver microbial and immune axes will provide new insights into the pathogenesis of these diseases.

The link among microbiota, epigenetics, and disease development

The microbiome is a community of various microorganisms that inhabit or live on the skin of humans/animals, sharing the body space with their hosts. It is a sort of complex ecosystem of trillions of commensals, symbiotic, and pathogenic microorganisms, including trillions of bacteria, archaea, protozoa, fungi, and viruses. The microbiota plays a role in the health and disease status of the host. Their number, species dominance, and viability are dynamic. Their long-term disturbance is usually accompanied by serious diseases such as metabolic disorders, cardiovascular diseases, or even cancer. While epigenetics is a term that refers to different stimuli that induce modifications in gene expression patterns without structural changes in the inherited DNA sequence, these changes can be reversible or even persist for several generations. Epigenetics can be described as cell memory that stores experience against internal and external factors. Results from multiple institutions have contributed to the role and close interaction of both microbiota and epigenetics in disease induction. Understanding the mechanisms of both players enables a better understanding of disease induction and development and also opens the horizon to revolutionary therapeutic approaches. The present review illustrates the roles of diet, microbiome, and epigenetics in the induction of several chronic diseases. In addition, it discusses the application of epigenetic data to develop diagnostic biomarkers and therapeutics and evaluate their safety for patients. Understanding the interaction among all these elements enables the development of innovative preventive/therapeutic approaches for disease control.

Genetic and environmental factors influencing the interaction between the gut microbiota and the human host: implications for gastrointestinal disorders and treatment approaches

The growing knowledge on the microbiota hosted in the human intestine has allowed researchers and clinicians to discover a critical role for these microorganisms in the pathogenesis of several human disorders. In particular, perturbation in the microbiotic strains populating the gastrointestinal tract has been associated with several conditions affecting the digestive system. The composition of the human gut microbiota is influenced by both genetic factors, like the human and the microbiotic genomes, and environmental ones, such as diet or drugs. Alteration of the interaction between the gut microbiota and the human host has been proven to be associated with several gastrointestinal disorders as well as potential effects on pharmacological therapies.

Lactobacillus Attenuate the Progression of Pancreatic Cancer Promoted by Porphyromonas Gingivalis in K-rasG12D Transgenic Mice

Simple Summary

Pancreatic cancer is aggressive and lethal with a five year survival rate of only 5–9%. While the exact pathogenesis of pancreatic cancer is not fully understood, oral pathogens associated with periodontitis, such as Porphyromonas gingivalis (P. gingivalis), are linked to the disease. The aim of our study was to investigate the causal association between exposure to P. gingivalis and subsequent carcinogenesis, and the potential modulatory effects of probiotics. We demonstrated that oral exposure to P. gingivalis can accelerate the development of pancreatic ductal adenocarcinoma in mouse models. In addition, the transforming growth factor-β (TGF-β) signaling pathway may be involved in the cancer-promoting effect of P. gingivalis and the suppressive effects of probiotics. Further understanding of the mechanisms of tumor-promoting or tumor-suppressing effects of TGF-β signaling may have potential as a treatment for pancreatic cancer.

Abstract

Accumulating evidence suggests that there is a link between the host microbiome and pancreatic carcinogenesis, and that Porphyromonas gingivalis (P. gingivalis) increases the risk of developing pancreatic cancer. The aim of the current study was to clarify the role of P. gingivalis in the pathogenesis of pancreatic cancer and the potential immune modulatory effects of probiotics. The six-week-old LSL-K-rasG12D; Pdx-1-cre (KC) mice smeared P. gingivalis on the gums, causing pancreatic intraepithelial neoplasia (PanIN) after four weeks to be similar to the extent of lesions in untreated KC mice at 24 weeks. The oral inoculation of P. gingivalis of six-week-old LSL-K-ras^G12D; Pdx-1-cre (KC) mice caused significantly pancreatic intraepithelial neoplasia (PanIN) after treatment four weeks is similar to the extent of lesions in untreated KC mice at 24 weeks. The pancreas weights of P. gingivalis plus probiotic-treated mice were significantly lower than the mice treated with P. gingivalis alone (P = 0.0028). The histological expressions of Snail-1, ZEB-1, collagen fibers, Galectin-3, and PD-L1 staining in the pancreas were also notably lower. In addition, probiotic administration reduced the histological expression of Smad3 and phosphorylated Smad3 in P. gingivalis treated KC mice. We demonstrated that oral exposure to P. gingivalis can accelerate the development of PanIN lesions. Probiotics are likely to have a beneficial effect by reducing cancer cell proliferation and viability, inhibiting PanIN progression, and cancer cell metastasis (Epithelial–mesenchymal transition, EMT). The transforming growth factor-β signaling pathway may be involved in the tumor suppressive effects of probiotics.