Gut Microbiota for Esophageal Cancer: Role in Carcinogenesis and Clinical Implications

Emerging importance of stool preservation methods in OMICS studies with special focus on cancer biology

The intricate consortium of microorganisms in the human gut plays a crucial role in different physiological functions. The complex known-unknown elements of the gut microbiome are perplexing and the absence of standardized procedures for collecting and preserving samples has hindered continuous research in comprehending it. The technological bias produced because of lack of standard protocols has affected the reproducibility of results. The complex nature of diseases like colorectal cancer, gastric cancer, hepatocellular carcinoma and breast cancer require a thorough understanding of its etiology for an efficient and timely diagnosis. The designated protocols for collection and preservation of stool specimens have great variance, hence generate inconsistencies in OMICS studies. Due to the complications associated to the nature of sample, it is important to preserve the sample to be studied later in a laboratory or to be used in the future research purpose. Stool preservation is gaining importance due to the increased use of treatment options like fecal microbiota transplantation to cure conditions like recurrent Clostridium difficile infections and for OMICS studies including metagenomics, metabolomics and culturomics. This review provides an insight into the importance of omics studies for the identification and development of novel biomarkers for quick and noninvasive diagnosis of various diseases.

Predicting the potential deterioration of Barrett's esophagus based on gut microbiota: a Mendelian randomization analysis

Esophageal adenocarcinoma (EAC) is one of the most malignant tumors in the digestive system. To make thing worse, the scarcity of treatment options is disheartening. However, if detected early, there is a possibility of reversing the condition. Unfortunately, there is still a lack of relevant early screening methods. Considering that Barrett's esophagus (BE), a precursor lesion of EAC, has been confirmed as the only known precursor of EAC. Analyzing which BE cases will progress to EAC and understanding the processes and mechanisms involved is of great significance for early screening of such patients. Considering the significant alterations in the gut microbiota of patients with BE and its potential role in the progression to EAC, this study aims to analyze the relationship between BE, EAC, and GM to identify potential diagnostic biomarkers and therapeutic targets. This study utilized comprehensive statistical data on gut microbiota from a large-scale genome-wide association meta-analysis conducted by the MiBioGen consortium (n = 18,340). Subsequently, we selected a set of single nucleotide polymorphisms (SNPs) that fell below the genome-wide significance threshold (1 × 10-5) as instrumental variables. To investigate the causal relationship between gut microbiota and BE and EAC, we employed various MR analysis methods, including Inverse Variance Weighting (IVW), MR-Egger regression, weighted median (WM), and weighted mean. Additionally, we assessed the level of pleiotropy, heterogeneity, and stability of genetic variations through MR-Egger intercept test, MR-PRESSO, Cochran's Q test, and "leave-one-out" sensitivity analysis. Furthermore, we conducted reverse MR analysis to identify the causal relationships between gut microbiota and BE and EAC. The results from the Inverse Variance-Weighted (IVW) analysis indicate that Alistipes (P = 4.86 × 10-2), Lactobacillus (P = 2.11 × 10-2), Prevotella 7 (P = 4.28 × 10-2), and RuminococcaceaeUCG004 (P = 4.34 × 10-2) are risk factors for Barrett's esophagus (BE), while Flavonifractor (P = 8.81 × 10-3) and RuminococcaceaeUCG004 (P = 4.99 × 10-2) are risk factors for esophageal adenocarcinoma (EAC). On the other hand, certain gut microbiota genera appear to have a protective effect against both BE and EAC. These include Eubacterium (nodatum group) (P = 4.51 × 10-2), Holdemania (P = 1.22 × 10-2), and Lactococcus (P = 3.39 × 10-2) in the BE cohort, as well as Eubacterium (hallii group) (P = 4.07 × 10-2) and Actinomyces (P = 3.62 × 10-3) in the EAC cohort. According to the results of reverse MR analysis, no significant causal effects of BE and EAC on gut microbiota were observed. Furthermore, no significant heterogeneity or pleiotropy was detected in the instrumental variables. We have established a causal relationship between the gut microbiota and BE and EAC. This study holds profound significance for screening BE patients who may be at risk of deterioration, as it can provide them with timely medical interventions to reverse the condition.

Salivary microbiome is associated with the response to chemoradiotherapy in initially inoperable patients with esophageal squamous cell carcinoma

Background

The salivary microbiome may interact with chemoradiotherapy through dynamic changes in microbial composition and systemic immunity. We aimed to explore the association between the salivary microbiome and response to chemoradiotherapy in initially inoperable patients with local advanced esophageal squamous cell carcinoma (LAESCC).

Methods

Salivary and peripheral blood samples were collected before and after chemoradiotherapy. The microbiome and metabolic pathways were analyzed by 16S ribosomal RNA sequencing and liquid chromatography tandem mass spectrometry/Mass spectrometry analyses.

Results

The salivary microbiome exhibited characteristic variations between patients and healthy controls. A significant correlation was found between Prevotella_salivae, Saccharibacteria_TM7_G3_bacterium_HMT_351, and Veillonellaceae_G1_bacterium_HMT_129 and pathological complete response (pCR) in initially inoperable patients who underwent surgery. The PICRUSt suggested that immune diseases and cell motility were different in tumor compared to normal groups. KEGG enrichment analysis showed enriched lipid metabolism, signal transduction, and membrane transport in the tumor group. CD3+CD8 T cells, IL6, IL10, and IFNγ exhibited an increasing trend during the treatment process of chemoradiotherapy.

Conclusions

Our study demonstrated that variations in specific saliva taxa associated with host immunomodulatory cells and cytokines could be promising for early efficacy prediction of chemoradiotherapy in initially inoperable patients with LAESCC.

The role of microbiomes in gastrointestinal cancers: new insights

Gastrointestinal (GI) cancers constitute more than 33% of new cancer cases worldwide and pose a considerable burden on public health. There exists a growing body of evidence that has systematically recorded an upward trajectory in GI malignancies within the last 5 to 10 years, thus presenting a formidable menace to the health of the human population. The perturbations in GI microbiota may have a noteworthy influence on the advancement of GI cancers; however, the precise mechanisms behind this association are still not comprehensively understood. Some bacteria have been observed to support cancer development, while others seem to provide a safeguard against it. Recent studies have indicated that alterations in the composition and abundance of microbiomes could be associated with the progression of various GI cancers, such as colorectal, gastric, hepatic, and esophageal cancers. Within this comprehensive analysis, we examine the significance of microbiomes, particularly those located in the intestines, in GI cancers. Furthermore, we explore the impact of microbiomes on various treatment modalities for GI cancer, including chemotherapy, immunotherapy, and radiotherapy. Additionally, we delve into the intricate mechanisms through which intestinal microbes influence the efficacy of GI cancer treatments.

Application of Mendelian randomization to assess host gene-gut microbiota correlations in patients with esophageal cancer

Background

Increasing evidence suggests that esophageal cancer (ESCA) may be correlated with gut flora. However, their causal connection remains unclear. This study aimed to evaluate potential causal linkages and gene-gut microbiome associations between the gut microbiota and ESCA using Mendelian randomization (MR).

Methods

We analyzed the data using genome-wide association studies. The exposure factor and outcome variable were the gut microbiota and ESCA, respectively. The MR-Egger method, weighted median, inverse-variance weighted method, heterogeneity test, sensitivity analysis, and multiplicity analysis were used for the MR analysis. And it was validated using an external dataset. Further meta-analysis was performed to validate the robustness of this relationship. Finally, we annotated single nucleotide polymorphisms in the gut microbiota that were causally associated with ESCA to explore possible host gene-gut microbiota correlations in patients with ESCA.

Results

We identified four species with potential associations with ESCA. Three of these species had a negative causal relationship with ESCA (odds ratio (OR): 0.961; 95% confidence interval (CI): 0.923-0.971; p = 0.047 for Romboutsia; OR: 0.972; 95% CI: 0.921-0.961; p = 0.018 for Lachnospira; OR: 0.948; 95% CI: 0.912-0.970; p = 0.032 for Eubacterium). A positive causal relationship was observed between one bacterial group and ESCA (OR: 1.105; 95% CI: 1.010-1.072; p = 0.018 for Veillonella). External datasets show the same trend. This is further supported by meta-analysis. None of the data showed pleiotropy, and leave-one-out analysis indicated the reliability of these findings. The gut microbiomes of patients with ESCA may correlate with the 19 identified genes.

Conclusion

Our data indicate a potential causal link between these four gut bacteria and ESCA and identify a correlation between host genes and gut microbiota in ESCA, offering novel therapeutic options.

Narrative Review of Probiotic Use on the Recovery of Postoperative Patients with Esophageal Cancer

PURPOSE OF REVIEW

This narrative review discusses the significance of probiotic therapy in the postoperative care of patients with esophageal cancer and its role as an adjunct therapy to other treatment modalities for esophageal cancer.

RECENT FINDINGS

As such, there is an emerging need to address any malnutrition and gastrointestinal problems occurring in these patients which tend to have a strong negative impact on their prognosis. Probiotic effects on esophageal cancer biomarkers suggest that there is a positive correlation between these two factors. However, the beneficial effects remain controversial and warrant further investigation. Probiotics, now being widely utilized as postoperative therapy in some carcinomas of the gastrointestinal tract such as gastric cancer and colorectal cancer, have been shown in some clinical studies to positively impact the nutritional status of patients with esophageal cancer. Postoperative care among patients suffering from esophageal cancer is a very crucial aspect in the survival of these patients.

Mechanisms by which the intestinal microbiota affects gastrointestinal tumours and therapeutic effects

The intestinal microbiota is considered to be a forgotten organ in human health and disease. It maintains intestinal homeostasis through various complex mechanisms. A significant body of research has demonstrated notable differences in the gut microbiota of patients with gastrointestinal tumours compared to healthy individuals. Furthermore, the dysregulation of gut microbiota, metabolites produced by gut bacteria, and related signal pathways can partially explain the mechanisms underlying the occurrence and development of gastrointestinal tumours. Therefore, this article summarizes the latest research progress on the gut microbiota and gastrointestinal tumours. Firstly, we provide an overview of the composition and function of the intestinal microbiota and discuss the mechanisms by which the intestinal flora directly or indirectly affects the occurrence and development of gastrointestinal tumours by regulating the immune system, producing bacterial toxins, secreting metabolites. Secondly, we present a detailed analysis of the differences of intestinal microbiota and its pathogenic mechanisms in colorectal cancer, gastric cancer, hepatocellular carcinoma, etc. Lastly, in terms of treatment strategies, we discuss the effects of the intestinal microbiota on the efficacy and toxic side effects of chemotherapy and immunotherapy and address the role of probiotics, prebiotics, FMT and antibiotic in the treatment of gastrointestinal tumours. In summary, this article provides a comprehensive review of the pathogenic mechanisms of and treatment strategies pertaining to the intestinal microbiota in patients with gastrointestinal tumours. And provide a more comprehensive and precise scientific basis for the development of microbiota-based treatments for gastrointestinal tumours and the prevention of such tumours.

Resident Esophageal Microbiota Dysbiosis Correlates with Cancer Risk in Barrett's Esophagus Patients and Is Linked to Low Adherence to WCRF/AICR Lifestyle Recommendations

Esophageal adenocarcinoma (EAC) is the consequence of longstanding gastroesophageal reflux, which leads to inflammation and could cause Barrett's esophagus (BE), the main risk factor for EAC development. The 5 year survival rate of EAC is poor since the diagnosis occurs at the late stage of the disease. To improve patient management, a better comprehension of the mechanism undergoing the evolution through to adenocarcinoma is needed. Within this scenario, the resident microbiome investigation was studied. This study aimed to explore the esophageal microbial profile in patients affected by non-dysplastic BE, low- and high-grade dysplastic BE, and EAC to identify parameters characterizing cancer progression and to develop a score suitable for clinical practice to stratify cancer risk. The microbiota was investigated through the 16S rRNA gene sequencing of esophageal biopsies. The microbial composition was evaluated at each different taxonomic level along the disease progression. To further investigate bacteria potentially associated with cancer development, non-dysplastic and dysplastic/cancer patients were compared. The presence of the six significant microbial features with multivariate analysis was used to develop a multiparametric score (Resident Esophageal Microbial Dysbiosis Test) to predict the risk of progression toward EAC. Finally, the diagnostic ability of the test and its discrimination threshold for its ability to identify dysplastic/cancer patients were demonstrated. Since EAC has been related to obesity, the relationship between these microbial parameters and patients' diet/lifestyle habits was also investigated. Developing microbiome-based risk prediction models for esophageal adenocarcinoma onset could open new research avenues, demonstrating that the resident microbiome may be a valid cancer risk biomarker.

Human microbiomes in cancer development and therapy

Colonies formed by bacteria, archaea, fungi, and viral groups and their genomes, metabolites, and expressed proteins constitute complex human microbiomes. An increasing evidences showed that carcinogenesis and disease progression were link to microbiomes. Different organ sources, their microbial species, and their metabolites are different; the mechanisms of carcinogenic or procancerous are also different. Here, we summarize how microbiomes contribute to carcinogenesis and disease progression in cancers of the skin, mouth, esophagus, lung, gastrointestinal, genital, blood, and lymph malignancy. We also insight into the molecular mechanisms of triggering, promoting, or inhibiting carcinogenesis and disease progress induced by microbiomes or/and their secretions of bioactive metabolites. And then, the strategies of application of microorganisms in cancer treatment were discussed in detail. However, the mechanisms by which human microbiomes function are still poorly understood. The bidirectional interactions between microbiotas and endocrine systems need to be clarified. Probiotics and prebiotics are believed to benefit human health via a variety of mechanisms, in particular, in tumor inhibition. It is largely unknown how microbial agents cause cancer or how cancer progresses. We expect this review may open new perspectives on possible therapeutic approaches of patients with cancer.

The Debate between the Human Microbiota and Immune System in Treating Aerodigestive and Digestive Tract Cancers: A Review

The human microbiota comprises a group of microorganisms co-existing in the human body. Unbalanced microbiota homeostasis may impact metabolic and immune system regulation, shrinking the edge between health and disease. Recently, the microbiota has been considered a prominent extrinsic/intrinsic element of cancer development and a promising milestone in the modulation of conventional cancer treatments. Particularly, the oral cavity represents a yin-and-yang target site for microorganisms that can promote human health or contribute to oral cancer development, such as Fusobacterium nucleatum. Moreover, Helicobacter pylori has also been implicated in esophageal and stomach cancers, and decreased butyrate-producing bacteria, such as Lachnospiraceae spp. and Ruminococcaceae, have demonstrated a protective role in the development of colorectal cancer. Interestingly, prebiotics, e.g., polyphenols, probiotics (Faecalibacterium, Bifidobacterium, Lactobacillus, and Burkholderia), postbiotics (inosine, butyrate, and propionate), and innovative nanomedicines can modulate antitumor immunity, circumventing resistance to conventional treatments and could complement existing therapies. Therefore, this manuscript delivers a holistic perspective on the interaction between human microbiota and cancer development and treatment, particularly in aerodigestive and digestive cancers, focusing on applying prebiotics, probiotics, and nanomedicines to overcome some challenges in treating cancer.

Role of tumor microenvironment in cancer progression and therapeutic strategy

Cancer is now considered a tumor microenvironment (TME) disease, although it was originally thought to be a cell and gene expression disorder. Over the past 20 years, significant advances have been made in understanding the complexity of the TME and its impact on responses to various anticancer therapies, including immunotherapies. Cancer immunotherapy can recognize and kill cancer cells by regulating the body's immune system. It has achieved good therapeutic effects in various solid tumors and hematological malignancies. Recently, blocking of programmed death-1 (PD-1), programmed death-1 ligand-1 (PD-L1), and programmed death Ligand-2 (PD-L2), the construction of antigen chimeric T cells (CAR-T) and tumor vaccines have become popular immunotherapies Tumorigenesis, progression, and metastasis are closely related to TME. Therefore, we review the characteristics of various cells and molecules in the TME, the interaction between PD-1 and TME, and promising cancer immunotherapy therapeutics.

Host Microbiomes Influence the Effects of Diet on Inflammation and Cancer

Cancer is the second leading cause of death globally, and there is a growing appreciation for the complex involvement of diet, microbiomes, and inflammatory processes culminating in tumorigenesis. Although research has significantly improved our understanding of the various factors involved in different cancers, the underlying mechanisms through which these factors influence tumor cells and their microenvironment remain to be completely understood. In particular, interactions between the different microbiomes, specific dietary factors, and host cells mediate both local and systemic immune responses, thereby influencing inflammation and tumorigenesis. Developing an improved understanding of how different microbiomes, beyond just the colonic microbiome, can interact with dietary factors to influence inflammatory processes and tumorigenesis will support our ability to better understand the potential for microbe-altering and dietary interventions for these patients in future.

Esophageal cancer and bacterial part of gut microbiota - A multidisciplinary point of view

There is an urgent need to search for new screening methods that allow early detection of esophageal cancer and thus achieve better clinical outcomes. Nowadays, it is known that the esophagus is not a sterile part of the gastrointestinal tract. It is colonized with various microorganisms therefore a "healthy" esophageal microbiome exists. The dysbiotic changes of esophageal microbiome can lead to the development of esophageal diseases including esophageal cancer. There is a strong consensus in the literature that the intestinal microbiome may be involved in esophageal carcinogenesis. Recently, emphasis has also been placed on the relationship between the oral microbiome and the occurrence of esophageal cancer. According to recent studies, some of the bacteria present in the oral cavity, such as Tannerella forsythia, Streptococcus anginosus, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, and Fusobacterium nucleatum may contribute to the development of this cancer. Moreover, the oral microbiome of patients with esophageal cancer differs significantly from that of healthy individuals. This opens new insights into the search for a microbiome-associated marker for early identification of patients at high risk for developing this cancer.

Comparison of tumor-associated and nontumor-associated esophageal mucosa microbiota in patients with esophageal squamous cell carcinoma

Esophageal microbiota plays important roles in esophageal squamous cell carcinoma (ESCC). The aims of this study were to clarify the changes in the bacterial community during ESCC development and identify latent pathogenic bacteria which may contribute to esophageal carcinogenesis and progression. Fresh tumor and nontumor esophageal mucosal samples were collected from 31 men with ESCC. High-throughput 16s rRNA sequencing was performed, and the operational taxonomic unit data and bacterial classification annotation were obtained and analyzed. The Ace, Chao, Shannon, Simpson indexes, and operational taxonomic unit numbers were higher in nontumor tissues than in tumor tissues, although without statistical significance. There were 4 phyla and 28 genera found to show significant differences between tumor and nontumor samples. The general probiotic Lactobacillus was 1.98-fold higher in nontumor tissues, while the general pathogenic genera Fusobacterium was 4.35-fold higher in tumor tissues. For tumor tissue samples, the genera Treponema and Brevibacillus were significantly higher in N1 and N2 stages, respectively, and Acinetobacter was significantly higher in T3 stage. For nontumor tissues, the genus Fusicatenibacter was significantly higher in T2 stage, and Corynebacterium, Aggregatibacter, Saccharimonadaceae-TM7x, and Cupriavidus were significantly higher in T4 stage. Additionally, bacteria related to nitrotoluene degradation were enriched in nontumor tissues, while bacteria related to base excision repair were enriched in tumor tissues. The relative abundance of several phyla and genera are different between tumor and nontumor tissue samples. The altered bacterial microbiota is correlated with different tumor stages and some microbes may take part in the carcinogenesis and development of ESCC.

Human Microbiome in Children, at the Crossroad of Social Determinants of Health and Personalized Medicine

The evolving field of microbiome research offers an excellent opportunity for biomarker identification, understanding drug metabolization disparities, and improving personalized medicine. However, the complexities of host-microbe ecological interactions hinder clinical transferability. Among other factors, the microbiome is deeply influenced by age and social determinants of health, including environmental factors such as diet and lifestyle conditions. In this article, the bidirectionality of social and host-microorganism interactions in health will be discussed. While the field of microbiome-related personalized medicine evolves, it is clear that social determinants of health should be mitigated. Furthermore, microbiome research exemplifies the need for specific pediatric investigation plans to improve children's health.