Postmenopausal breast cancer and oestrogen associations with the IgA-coated and IgA-noncoated faecal microbiota

The estrobolome: Estrogen-metabolizing pathways of the gut microbiome and their relation to breast cancer

Increasing evidence links the gut microbiome to carcinogenesis. Disruptions in estrogen regulation by the estrobolome-gut microbiota with estrogen-related functions-may promote breast cancer. However, precise information on estrobolome targets and their underlying mechanisms is limited. This review identifies relevant targets for measuring the estrobolome, focusing on enzymes and microbial taxa involved in processing estrogens, precursors, metabolites, and phytoestrogens, to facilitate the exploration of potential links to breast cancer. Evidence from breast cancer case-control studies is synthesized to assess alignment with these targets, highlight gaps in the evidence, and suggest new paths forward. Findings from case-control studies were heterogeneous and showed limited alignment with estrobolome targets, with only Escherichia coli and Roseburia inulinivorans identified as differentially abundant and functionally relevant between cases and controls. The lack of compelling evidence for estrobolome-specific mechanisms may reflect measurement challenges or may suggest that broader ecological changes in the microbiome, which influence a network of interacting mechanisms, are more influential for carcinogenesis. To clarify the estrobolome's role in breast cancer, future research should use advanced sequencing techniques and methods such as metabolomics and transcriptomics, while considering clinical and behavioral factors that may modify estrobolome mechanisms.

Gut microbiota reshapes the TNBC immune microenvironment: Emerging immunotherapeutic strategies

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer with limited treatment options and poor prognosis. The gut microbiota, a diverse community of microorganisms in the gastrointestinal tract, plays a crucial role in regulating immune responses through the gut-immune axis. Recent studies have highlighted its significant impact on TNBC progression and the efficacy of immunotherapies. This review examines the interactions between gut microbiota and the immune system in TNBC, focusing on key immune cells and pathways involved in tumor immunity. It also explores microbiota modulation strategies, including probiotics, prebiotics, dietary interventions, and fecal microbiota transplantation, as potential methods to enhance immunotherapeutic outcomes. Understanding these mechanisms offers promising avenues for improving treatment efficacy and patient prognosis in TNBC.

Huaier enhances the antitumor effects of CDK 4/6 inhibitor by remodeling the immune microenvironment and gut microbiota in breast cancer

ETHNOPHARMACOLOGICAL RELEVANCE

Trametes robiniophila Murr (Huaier), a traditional Chinese medicine (TCM), has shown promising effects as a complementary therapy in the treatment of multiple kinds of cancers.

AIM OF THE STUDY

This study aimed to systematically evaluate whether Huaier could enhance the antitumor effects of palbociclib, a highly selective CDK4/6 inhibitor.

MATERIALS AND METHODS

A breast cancer xenograft mouse model was constructed to assess the anticancer effects of Huaier and palbociclib. Transcriptomic analysis was performed to identify the differentially expressed genes and associated pathways. Flow cytometry, immunofluorescence and immunohistochemical staining were then conducted to observe the infiltration of immune cells in the tumor microenvironment (TME). The composition of the gut microbiota was explored through 16S rDNA sequencing, and a pseudosterile mouse model was established to verify the contribution of the gut microbiota to the antitumor effects of Huaier and palbociclib.

RESULTS

Oral administration of Huaier enhanced the antitumor effects of palbociclib in breast cancer. Transcriptomic analysis of tumor tissues revealed that the differentially expressed genes were related to immune functions. Indeed, the addition of Huaier to palbociclib therapy further increased the ratio of CD8+/CD3+ T cells and the abundance of GzmB+CD8+ T cells in the TME. Mechanistically, sequencing of 16S rDNA revealed that Huaier reshaped the gut microbiota composition in favor of Akkermansia, which positively modulated antitumor immune responses. The pseudosterile mouse model verified the necessity of the gut microbiota for the synergistic effect of Huaier on palbociclib. Furthermore, butyrate, a metabolite of Akkermansia, synergized with palbociclib to suppress tumor progression and promote the infiltration of CD8+ T cells in the TME.

CONCLUSIONS

Our data suggested that Huaier augmented the antitumor effects of palbociclib by increasing the abundance of Akkermansia in gut microbiota, which contributed to the enhancement of anti-tumor immunity. Consequently, combining palbociclib with Huaier may serve as a promising strategy for the treatment of breast cancer.

Multiple primary malignancies and gut microbiome

BACKGROUND

Multiple primary malignancies (MPM) are two or more independent primary malignancies. Recently, the relationship between microbiome and various tumors has been gradually focused on.

OBJECTIVE

To describe the relationship between MPM patients (MPMs) and gut microbiome.

METHODS

A total of 27 MPMs, 30 colorectal cancer patients (CRCs), and 30 healthy individuals were included to obtain metagenomic sequencing data. The knowledge graphs of gut bacteria and enteroviruses were plotted based on metagenomics. Wilcoxon rank-sum test was used to screen the characteristic gut microbiome.

RESULTS

The knowledge graph of gut microbiome in MPM patients was plotted. A total of 26 different gut bacteria, including Dialister, Fecalibacterium and Mediterraneibacter, were found between MPMs and healthy individuals. Twenty gut bacteria, including Parvimonas, Dialister and Mediterraneibacter, were more abundant in MPM complicated by CRC compared with CRCs. Twenty-one different enterovirus, including Triavirus, Punavirus and Lilyvirus, were screened between MPMs and healthy individuals. Triavirus, Punavirus and Lilyvirus were less abundant in MPM than healthy individuals. The abundance of Triavirus, Punavirus and Lilyvirus in CRC patients were also lower than MPM complicated by CRC patients.

CONCLUSION

The knowledge graph of gut microbiome in MPM patients was plotted. It may provide basic data support for future research of MPM.

Gut microbiota and breast cancer: systematic review and meta-analysis

BACKGROUND

The gastrointestinal microbiota can modulate systemic estrogens, potentially influencing estrogen-induced breast neoplasia development. This study aimed to assess alterations in the gut microbiota in breast cancer patients.

METHODS

A search strategy was developed using the terms: "Microbiota," "Gastrointestinal Microbiome," "Breast Cancer," and synonyms. Ten observational studies were included.

RESULTS

The total sample was 1730 women (929 cases and 801 controls). The meta-analysis of alpha diversity, assessed by the Shannon index, displayed that in the breast cancer group, the diversity of the gut microbiota was reduced compared to controls, with a standardized mean difference (SMD) of - 0.34 (95% CI - 0.59, - 0.10, I2 = 68%, p = 0.007). Regarding the premenopausal population, there was a significant reduction in the breast cancer group (SMD - 0.67, 95% CI - 1.06, - 0.28, I2 = 77%, p = 0.0009). In women with a body mass index (BMI) between overweight or obesity, no statistically significant difference was observed (SMD - 0.20; 95% CI - 0.51, 0.11; I2 52%, p = 0.20). However, in women with a BMI greater than or equal to 18.5 and less than 25.0, there was lower diversity in women with breast cancer compared to controls (SMD - 0.49, 95% CI - 0.94, - 0.04; I2 78%, p = 0.03).

CONCLUSIONS

The study found a significant difference in gut microbiota diversity between women with breast cancer and controls, supporting the growing evidence that the gut microbiota may play a role in mammary carcinogenesis.

Dysbiosis and extraintestinal cancers

The gut microbiota plays a crucial role in safeguarding host health and driving the progression of intestinal diseases. Despite recent advances in the remarkable correlation between dysbiosis and extraintestinal cancers, the underlying mechanisms are yet to be fully elucidated. Pathogenic microbiota, along with their metabolites, can undermine the integrity of the gut barrier through inflammatory or metabolic pathways, leading to increased permeability and the translocation of pathogens. The dissemination of pathogens through the circulation may contribute to the establishment of an immune-suppressive environment that promotes carcinogenesis in extraintestinal organs either directly or indirectly. The oncogenic cascade always engages in the disruption of hormonal regulation and inflammatory responses, the induction of genomic instability and mutations, and the dysregulation of adult stem cell proliferation. This review aims to comprehensively summarize the existing evidence that points to the potential role of dysbiosis in the malignant transformation of extraintestinal organs such as the liver, breast, lung, and pancreas. Additionally, we delve into the limitations inherent in current methodologies, particularly the challenges associated with differentiating low loads gut-derived microbiome within tumors from potential sample contamination or symbiotic microorganisms. Although still controversial, an understanding of the contribution of translocated intestinal microbiota and their metabolites to the pathological continuum from chronic inflammation to tumors could offer a novel foundation for the development of targeted therapeutics.

Interactions between the tumor microbiota and breast cancer

Breast cancer is the most common malignancy in women worldwide. Changes in the microbiota and their metabolites affect the occurrence and development of breast cancer; however, the specific mechanisms are not clear. Gut microbes and their metabolites influence the development of breast cancer by regulating the tumor immune response, estrogen metabolism, chemotherapy, and immunotherapy effects. It was previously thought that there were no microorganisms in breast tissue, but it is now thought that there are microorganisms in breast cancer that can affect the outcome of the disease. This review builds on existing research to comprehensively analyze the role of gut and intratumoral microbiota and their metabolites in the development and metastasis of breast cancer. We also explore the potential function of the microbiota as biomarkers for prognosis and therapeutic response, highlighting the need for further research to clarify the causal relationship between the microbiota and breast cancer. We hope to provide new ideas and directions for the development of new methods for breast cancer treatment.

Intratumoral Stenotrophomonas Maltophilia in Breast Cancer: Unraveling the Interplay with Hormone Receptors and Impact on Tumor Immunity

This study aimed to explore the impact of intratumoral microorganisms in conjunction with hormone receptors on the tumor microenvironment and their potential role in predicting patient prognosis. Significant bacterial variations were identified within ER, PR, HER2, and triple-negative breast cancer subtypes. Kaplan-Meier survival analysis was employed to identify bacteria associated with patient survival. Further, a humanized immune system mouse model bearing breast cancer xenografts was used to evaluate the effects of Stenotrophomonas maltophilia (SMA) on tumor growth and CD8+ T cell infiltration. Additional validation experiments included fluorescence in situ hybridization for SMA, CD8+ T cell chemotaxis, and intracellular cytokine detection. Lawsonella clevelandensis-A, Diaphorobacter nitroreducens, and SMA were identified as significant prognostic species. Notably, tumor-infiltrating immune cells, particularly CD8+ T cells, exhibited a positive association with the presence of SMA. Experimental validation with clinically isolated SMA further confirmed its positive correlation with CD8+ T cell activation. In vivo findings demonstrated that SMA inhibited tumor growth and promoted CD8+ T cell infiltration, highlighting the complex interactions between intratumoral microbiota and tumor immunity in breast cancer. These insights contribute to the understanding of microbial influences on the tumor microenvironment and suggest potential pathways for improving patient prognosis through microbiota modulation.

Specific microbiome patterns and their association with breast cancer: the intestinal microbiota as a potential biomarker and therapeutic strategy

Breast cancer (BC) is one of the most diagnosed cancers in women. Based on histological characteristics, they are classified as non-invasive, or in situ (tumors located within the milk ducts or milk lobules) and invasive. BC may develop from in situ carcinomas over time. Determining prognosis and predicting response to treatment are essential tools to manage this disease and reduce its incidence and mortality, as well as to promote personalized therapy for patients. However, over half of the cases are not associated with known risk factors. In addition, some patients develop resistance to treatment and relapse. Therefore, it is necessary to identify new biomarkers and treatment strategies that improve existing therapies. In this regard, the role of the microbiome is being researched as it could play a role in carcinogenesis and the efficacy of BC therapies. This review aims to describe specific microbiome patterns associated with BC. For this, a literature search was carried out in PubMed database using the MeSH terms "Breast Neoplasms" and "Gastrointestinal Microbiome", including 29 publications. Most of the studies have focused on characterizing the gut or breast tissue microbiome of the patients. Likewise, studies in animal models and in vitro that investigated the impact of gut microbiota (GM) on BC treatments and the effects of the microbiome on tumor cells were included. Based on the results of the included articles, BC could be associated with an imbalance in the GM. This imbalance varied depending on molecular type, stage and grade of cancer, menopause, menarche, body mass index, and physical activity. However, a specific microbial profile could not be identified as a biomarker. On the other hand, some studies suggest that the GM may influence the efficacy of BC therapies. In addition, some microorganisms and bacterial metabolites could improve the effects of therapies or influence tumor development.

Prognostic value of tumor-infiltrating lymphocyte subtypes and microorganisms in triple-negative breast cancer

ABSTRACT

Tumor-infiltrating lymphocytes (TILs) are key components of the tumor microenvironment (TME) and serve as prognostic markers for breast cancer. Patients with high TIL infiltration generally experience better clinical outcomes and extended survival compared to those with low TIL infiltration. However, as the TME is highly complex and TIL subtypes perform distinct biological functions, TILs may only provide an approximate indication of tumor immune status, potentially leading to biased prognostic results. Therefore, we reviewed the interactions between immune-infiltrating subtypes and tumor cells throughout the entire TME. By examining the antitumor or protumor effects of each TIL subtype, we aimed to better characterize the tumor immune landscape, offering more accurate and comprehensive insights for guiding triple-negative breast cancer (TNBC) treatment. In addition, this approach could lead to the development of new therapeutic targets, enabling tailored treatment strategies and precision medicine. Accumulating evidence suggests that the intestinal microbiome and its metabolites influence antitumor responses by modulating innate and adaptive immunity, with specific bacteria potentially serving as biomarkers for predicting clinical responses. Various studies have identified microorganisms in breast tissue, previously considered sterile, revealing differences in breast microbial composition between patients with breast cancer and controls, as well as associations between specific breast microorganisms and clinicopathologic features, including immune correlations. The aim of this review was to provide a more comprehensive set of prognostic markers for TNBC and to tap into potential-specific therapeutic targets.

Exploring bacterial key genes and therapeutic agents for breast cancer among the Ghanaian female population: Insights from In Silico analyses

Breast cancer (BC) is yet a significant global health challenge across various populations including Ghana, though several studies on host-genome associated with BC have been investigated molecular mechanisms of BC development and progression, and candidate therapeutic agents. However, a little attention has been given on microbial genome in this regard, although alterations in microbiota and epigenetic modifications are recognized as substantial risk factors for BC. This study focused on identifying bacterial key genes (bKGs) associated with BC infections in the Ghanaian population and exploring potential drug molecules by targeting these bKGs through in silico analyses. At first, 16S rRNA bacterial sequence data were downloaded from NCBI database comprising 520 samples from BC patients and 442 from healthy controls. Analysis of 16S rRNA-Seq data showed significant differences in bacterial abundance between BC and healthy groups and identified 26 differential genera with the threshold values at |log2FC|>2.0 and p-value≤0.05. It was observed that two genera Prevotella and Anaerovibria are significantly upregulated in BC patients and others are downregulated. Functional analysis based on all differential genera identified 19 MetaCyc signaling pathways, twelve of which were significantly enriched in BC patients by containing 165 genes Top-ranked 10 genes mdh, pykF, gapA, zwf, pgi, tpiA, pgk, pfkA, ppsA, and pykA were identified as BC-causing bacterial key genes (bKGs) through protein-protein interaction network analysis. Subsequently, the bKG-guided top ranked 10 drug molecules Digitoxin, Digoxin, Ledipasvir, Suramin, Ergotamine, Venetoclax, Nilotinib, Conivaptan, Dihydroergotamine, and Elbasvir were identified using molecular docking analysis. The stability of top-ranked three drug-target complexes (Digitoxin-pykA, Digoxin-mdh, and Ledipasvir-pgi) were confirmed through the molecular dynamics simulation studies. Therefore, these findings might be useful resources to the wet-lab researchers for further experimental validation on bacterial therapies against BC.

Visceral adiposity in postmenopausal women is associated with a pro-inflammatory gut microbiome and immunogenic metabolic endotoxemia

BACKGROUND

Obesity, and in particular abdominal obesity, is associated with an increased risk of developing a variety of chronic diseases. Obesity, aging, and menopause are each associated with differential shifts in the gut microbiome. Obesity causes chronic low-grade inflammation due to increased lipopolysaccharide (LPS) levels which is termed "metabolic endotoxemia." We examined the association of visceral adiposity tissue (VAT) area, circulating endotoxemia markers, and the gut bacterial microbiome in a cohort of aged postmenopausal women.

METHODS

Fifty postmenopausal women (mean age 78.8 ± 5.3 years) who had existing adipose measurements via dual x-ray absorptiometry (DXA) were selected from the extremes of VAT: n = 25 with low VAT area (45.6 ± 12.5 cm2) and n = 25 with high VAT area (177.5 ± 31.3 cm2). Dietary intake used to estimate the Healthy Eating Index (HEI) score was assessed with a food frequency questionnaire. Plasma LPS, LPS-binding protein (LBP), anti-LPS antibodies, anti-flagellin antibodies, and anti-lipoteichoic acid (LTA) antibodies were measured by ELISA. Metagenomic sequencing was performed on fecal DNA. Female C57BL/6 mice consuming a high-fat or low-fat diet were treated with 0.4 mg/kg diet-derived fecal isolated LPS modeling metabolic endotoxemia, and metabolic outcomes were measured after 6 weeks.

RESULTS

Women in the high VAT group showed increased Proteobacteria abundance and a lower Firmicutes/Bacteroidetes ratio. Plasma LBP concentration was positively associated with VAT area. Plasma anti-LPS, anti-LTA, and anti-flagellin IgA antibodies were significantly correlated with adiposity measurements. Women with high VAT showed significantly elevated LPS-expressing bacteria compared to low VAT women. Gut bacterial species that showed significant associations with both adiposity and inflammation (anti-LPS IgA and LBP) were Proteobacteria (Escherichia coli, Shigella spp., and Klebsiella spp.) and Veillonella atypica. Healthy eating index (HEI) scores negatively correlated with % body fat and anti-LPS IgA antibodies levels. Preclinical murine model showed that high-fat diet-fed mice administered a low-fat diet fecal-derived LPS displayed reduced body weight, decreased % body fat, and improved glucose tolerance test parameters when compared with saline-injected or high-fat diet fecal-derived LPS-treated groups consuming a high-fat diet.

CONCLUSIONS

Increased VAT in postmenopausal women is associated with elevated gut Proteobacteria abundance and immunogenic metabolic endotoxemia markers. Low-fat diet-derived fecal-isolated LPS improved metabolic parameters in high-fat diet-fed mice giving mechanistic insights into potential pro-health signaling mediated by under-acylated LPS isoforms. Video Abstract.

Pharmacomicrobiomics in precision cancer therapy: bench to bedside

The burgeoning field of pharmacomicrobiomics offers promising insights into the intricate interplay between the microbiome and cancer, shaping responses to diverse treatment modalities. This review aims to analyze the molecular mechanisms underlying interactions between distinct microbiota types and cancer, as well as their influence on treatment outcomes. We explore how the microbiome impacts antitumor immunity, and response to chemotherapy, immunotherapy, and radiation therapy, unveiling its multifaceted roles in cancer progression and therapy resistance. Moreover, we discuss the challenges hindering the development of microbiome-based interventions in cancer therapy, including standardization, validation, and clinical translation. By synthesizing clinical evidence, we underscore the transformative potential of harnessing pharmacomicrobiomics in guiding cancer treatment decisions, paving the way for improved patient outcomes in clinical practice.

Obesity, dysbiosis and inflammation: interactions that modulate the efficacy of immunotherapy

Recent years have seen an outstanding growth in the understanding of connections between diet-induced obesity, dysbiosis and alterations in the tumor microenvironment. Now we appreciate that gut dysbiosis can exert important effects in distant target tissues via specific microbes and metabolites. Multiple studies have examined how diet-induced obese state is associated with gut dysbiosis and how gut microbes direct various physiological processes that help maintain obese state in a bidirectional crosstalk. Another tightly linked factor is sustained low grade inflammation in tumor microenvironment that is modulated by both obese state and dysbiosis, and influences tumor growth as well as response to immunotherapy. Our review brings together these important aspects and explores their connections. In this review, we discuss how obese state modulates various components of the breast tumor microenvironment and gut microbiota to achieve sustained low-grade inflammation. We explore the crosstalk between different components of tumor microenvironment and microbes, and how they might modulate the response to immunotherapy. Discussing studies from multiple tumor types, we delve to find common microbial characteristics that may positively or negatively influence immunotherapy efficacy in breast cancer and may guide future studies.

The immunoregulatory role of gut microbiota in the incidence, progression, and therapy of breast cancer

Breast cancer (BrCa) is the most prevalent malignant tumor in women and one of the leading causes of female mortality. Its occurrence and progression are influenced by various factors, including genetics, environment, lifestyle, and hormones. In recent years, the gut microbiota has been identified as a significant factor affecting BrCa. The gut microbiota refers to the collective population of various microorganisms in the human gastrointestinal tract. Gut microbiota is closely associated with human health and disease development, participating in crucial physiological functions such as digestion, metabolism, immune response, and neural regulation. It has been found to influence the occurrence and treatment of BrCa through a variety of mechanisms. This article aims to review the immunomodulatory role of the gut microbiota in the development and treatment of BrCa.

Changes in the fecal microbiota of breast cancer patients based on 16S rRNA gene sequencing: a systematic review and meta-analysis

PURPOSE

Breast cancer (BC) is a devastating disease for women. Microbial influences may be involved in the development and progression of breast cancer. This study aimed to investigate the difference in intestinal flora abundance between breast cancer patients and healthy controls (HC) based on previous 16S ribosomal RNA (rRNA) gene sequencing results, which have been scattered and inconsistent in previous studies.

MATERIALS AND METHODS

In agreement with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), we searched for pertinent literature in Pubmed, Embase, Cochrane Library, and Web of Science databases from build until February 1, 2023. Relative abundance, diversity of intestinal microflora by level, microbial composition, community structure, diversity index, and other related data were extracted. We used a fixed or random effects model for data analysis. We also conducted funnel plot analysis, sensitivity analysis, Egger's, and Begg's tests to assess the bias risk.

RESULTS

A total of ten studies involving 734 BC patients were enrolled. It was pointed out that there were significant differences in the Chao index between BC and HC in these studies [SMD = - 175.44 (95% CI - 246.50 to - 104.39)]. The relative abundance of Prevotellaceae [SMD = - 0.27 (95% CI - 0.39 to - 0.15)] and Bacteroides [SMD = 0.36 (95% CI 0.23-0.49)] was significantly different. In the included articles, the relative abundance of Prevotellaceae, Ruminococcus, Roseburia inulinivorans, and Faecalibacterium prausnitzii decreased in BC. Accordingly, the relative richness of Erysipelotrichaceae was high in BC.

CONCLUSIONS

This observational meta-analysis revealed that the changes in gut microbiota were correlated with BC, and the changes in some primary fecal microbiota might affect the beginning of breast cancer.

Exploring the impact of breast cancer on colonization resistance of mouse microbiota using network node manipulation

Breast cancer, a global health concern affecting women, has been linked to alterations in the gut microbiota, impacting various aspects of human health. This study investigates the interplay between breast cancer and the gut microbiome, particularly focusing on colonization resistance-an essential feature of the microbiota's ability to prevent pathogenic overgrowth. Using a mouse model of breast cancer, we employ diversity analysis, co-occurrence network analysis, and robustness tests to elucidate the impact of breast cancer on microbiome dynamics. Our results reveal that breast cancer exposure affects the bacterial community's composition and structure, with temporal dynamics playing a role. Network analysis demonstrates that breast cancer disrupts microbial interactions and decreases network complexity, potentially compromising colonization resistance. Moreover, network robustness analysis shows the susceptibility of the microbiota to node removal, indicating potential vulnerability to pathogenic colonization. Additionally, predicted metabolic profiling of the microbiome highlights the significance of the enzyme EC 6.2.1.2 - Butyrate--CoA ligase, potentially increasing butyrate, and balancing the reduction of colonization resistance. The identification of Rubrobacter as a key contributor to this enzyme suggests its role in shaping the microbiota's response to breast cancer. This study uncovers the intricate relationship between breast cancer, the gut microbiome, and colonization resistance, providing insights into potential therapeutic strategies and diagnostic approaches for breast cancer patients.

Exploring the underlying correlation between microbiota, immune system, hormones, and inflammation with breast cancer and the role of probiotics, prebiotics and postbiotics

According to recent research, bacterial imbalance in the gut microbiota and breast tissue may be linked to breast cancer. It has been discovered that alterations in the makeup and function of different types of bacteria found in the breast and gut may contribute to growth and advancement of breast cancer in several ways. The main role of gut microbiota is to control the metabolism of steroid hormones, such as estrogen, which are important in raising the risk of breast cancer, especially in women going through menopause. On the other hand, because the microbiota can influence mucosal and systemic immune responses, they are linked to the mutual interactions between cancer cells and their local environment in the breast and the gut. In this regard, the current review thoroughly explains the mode of action of probiotics and microbiota to eradicate the malignancy. Furthermore, immunomodulation by microbiota and probiotics is described with pathways of their activity.

Breast cancer but not the menopausal status is associated with small changes of the gut microbiota

Background

Possible relationships between gut dysbiosis and breast cancer (BC) development and progression have been previously reported. However, the results of these metagenomics studies are inconsistent. Our study involved 88 patients diagnosed with breast cancer and 86 cancer-free control women. Participants were divided into groups based on their menopausal status. Fecal samples were collected from 47 and 41 pre- and postmenopausal newly diagnosed breast cancer patients and 51 and 35 pre- and postmenopausal controls, respectively. In this study, we performed shotgun metagenomic analyses to compare the gut microbial community between pre- and postmenopausal BC patients and the corresponding controls.

Results

Firstly, we identified 12, 64, 158, and 455 bacterial taxa on the taxonomy level of phyla, families, genera, and species, respectively. Insignificant differences of the Shannon index and β-diversity were found at the genus and species levels between pre- and postmenopausal controls; the differences concerned only the Chao index at the species level. No differences in α-diversity indexes were found between pre- and postmenopausal BC patients, although β-diversity differed these subgroups at the genus and species levels. Consistently, only the abundance of single taxa differed between pre- and postmenopausal controls and cases, while the abundances of 14 and 23 taxa differed or tended to differ between premenopausal cases and controls, and between postmenopausal cases and controls, respectively. There were similar differences in the distribution of enterotypes. Of 460 bacterial MetaCyc pathways discovered, no pathways differentiated pre- and postmenopausal controls or BC patients, while two and one pathways differentiated cases from controls in the pre- and postmenopausal subgroups, respectively.

Conclusion

While our findings did not reveal an association of changes in the overall microbiota composition and selected taxa with the menopausal status in cases and controls, they confirmed differences of the gut microbiota between pre- and postmenopausal BC patients and the corresponding controls. However, these differences were less extensive than those described previously.

Alterations of Gastrointestinal Microbe Composition in Various Human Diseases and Its Significance in the Early Diagnosis of Diseases

A 100 trillion bacteria, viruses, fungi, and archaea make up the human gut microbe. It has co-evolved with its human host and carries out essential tasks that improve general health. The relationship between gastrointestinal microbes and human health has been a growing field of interest and research in recent times. The gastrointestinal microbes are connected by complex networks and connections, and the host has given birth to the gut-microbe-brain axis, which shows the crucial effect that this circumstance could have on the health and diseases of the brain and spinal cord (or the central nervous system [CNS]). The microbe and the CNS interact bi-directionally via autonomic, neuroendocrine, gastrointestinal, and immune system pathways. The gut microbe has been connected to a range of gastrointestinal and extra-gastrointestinal diseases. The recent investigation supports the suspicion that the gut-microbe-brain axis could play a role in neuropsychiatric disorders including depression, dementia, post-traumatic stress disorder, anxiousness, bipolar disorder, schizophrenia, and obsessive-compulsive disorder, alongside chronic host illnesses such as obesity, diabetes, and inflammation. Studies point to gut microorganisms as possible biomarkers for a wide range of mental health issues. Changes in the gut microbe may be a crucial factor in the onset and advancement of non-alcoholic fatty liver damage. Gut microbes have been seen to influence microglia's response to the CNS's regional signals and thus to pain and inflammation. Data suggest that altering the gut microbe in those with chronic pain may be a successful method for reducing pain. Numerous investigations have documented alterations in the gut microbes made in Alzheimer patients and schizophrenic patients. The risk of breast cancer can be reduced by restoring gut microbe homeostasis and reducing systemic estrogen levels.

Environmental cadmium exposure facilitates mammary tumorigenesis via reprogramming gut microbiota-mediated glutamine metabolism in MMTV-Erbb2 mice

Cadmium (Cd) is a heavy metal that has been widely reported to be linked to the onset and progression of breast cancer (BC). However, the mechanism of Cd-induced mammary tumorigenesis remains elusive. In our study, a transgenic mouse model that spontaneously develops tumors through overexpression of wild-type Erbb2 (MMTV-Erbb2) was constructed to investigate the effects of Cd exposure on BC tumorigenesis. The results showed that oral exposure to 3.6 mg/L Cd for 23 weeks dramatically accelerated tumor appearance and growth, increased Ki67 density and enhanced focal necrosis and neovascularization in the tumor tissue of MMTV-Erbb2 mice. Notably, Cd exposure enhanced glutamine (Gln) metabolism in tumor tissue, and 6-diazo-5-oxo-l-norleucine (DON), a Gln metabolism antagonist, inhibited Cd-induced breast carcinogenesis. Then our metagenomic sequencing and mass spectrometry-based metabolomics confirmed that Cd exposure disturbed gut microbiota homeostasis, especially Helicobacter and Campylobacter abundance remodeling, which altered the gut metabolic homeostasis of Gln. Moreover, intratumoral Gln metabolism profoundly increased under Cd-elevated gut permeability. Importantly, depletion of microbiota with an antibiotic cocktail (AbX) treatment led to a significant delay in the appearance of palpable tumors, inhibition of tumor growth, decrease in tumor weight, reduction in Ki67 expression and low-grade pathology in Cd-exposed MMTV-Erbb2 mice. Also, transplantation of Cd-modulated microbiota decreased tumor latency, accelerated tumor growth, increased tumor weight, upregulated Ki67 expression and exacerbated neovascularization as well as focal necrosis in MMTV-Erbb2 mice. In summary, Cd exposure induced gut microbiota dysbiosis, elevated gut permeability and increased intratumoral Gln metabolism, leading to the promotion of mammary tumorigenesis. This study provides novel insights into environmental Cd exposure-mediated carcinogenesis.

Unraveling the connections between gut microbiota, stress, and quality of life for holistic care in newly diagnosed breast cancer patients

There is little research about the stress, quality of life (QOL) and gut microbiota in newly diagnosed breast cancer patients. In this study addressing the dearth of research on stress, quality of life (QOL), and gut microbiota in newly diagnosed breast cancer patients, 82 individuals were prospectively observed. Utilizing the Functional Assessment of Chronic Illness Therapy (FACT)-Breast questionnaire to assess health-related quality of life (HRQOL) and the Distress Thermometer (DT) to gauge distress levels, the findings revealed a mean FACT-B score of 104.5, underscoring HRQOL's varied impact. Significantly, 53.7% reported moderate to severe distress, with a mean DT score of 4.43. Further exploration uncovered compelling links between distress levels, FACT-B domains, and microbial composition. Notably, Alcaligenaceae and Sutterella were more abundant in individuals with higher DT scores at the family and genus levels (p = 0.017), while Streptococcaceae at the family level and Streptococcus at the genus level were prevalent in those with lower DT scores (p = 0.028 and p = 0.023, respectively). This study illuminates the intricate interplay of stress, QOL, and gut microbiota in newly diagnosed breast cancer patients, offering valuable insights for potential interventions of biomarker or probiotics aimed at alleviating stress and enhancing QOL in this patient cohort.

Associations of Circulating Estrogens and Estrogen Metabolites with Fecal and Oral Microbiome in Postmenopausal Women in the Ghana Breast Health Study

The human fecal and oral microbiome may play a role in the etiology of breast cancer through modulation of endogenous estrogen metabolism. This study aimed to investigate associations of circulating estrogens and estrogen metabolites with the fecal and oral microbiome in postmenopausal African women. A total of 117 women with fecal (N = 110) and oral (N = 114) microbiome data measured by 16S rRNA gene sequencing, and estrogens and estrogen metabolites data measured by liquid chromatography tandem mass spectrometry were included. The outcomes were measures of the microbiome and the independent variables were the estrogens and estrogen metabolites. Estrogens and estrogen metabolites were associated with the fecal microbial Shannon index (global P < 0.01). In particular, higher levels of estrone (β = 0.36, P = 0.03), 2-hydroxyestradiol (β = 0.30, P = 0.02), 4-methoxyestrone (β = 0.51, P = 0.01), and estriol (β = 0.36, P = 0.04) were associated with higher levels of the Shannon index, while 16alpha-hydroxyestrone (β = -0.57, P < 0.01) was inversely associated with the Shannon index as indicated by linear regression. Conjugated 2-methoxyestrone was associated with oral microbial unweighted UniFrac as indicated by MiRKAT (P < 0.01) and PERMANOVA, where conjugated 2-methoxyestrone explained 2.67% of the oral microbial variability, but no other estrogens or estrogen metabolites were associated with any other beta diversity measures. The presence and abundance of multiple fecal and oral genera, such as fecal genera from families Lachnospiraceae and Ruminococcaceae, were associated with several estrogens and estrogen metabolites as indicated by zero-inflated negative binomial regression. Overall, we found several associations of specific estrogens and estrogen metabolites and the fecal and oral microbiome. IMPORTANCE Several epidemiologic studies have found associations of urinary estrogens and estrogen metabolites with the fecal microbiome. However, urinary estrogen concentrations are not strongly correlated with serum estrogens, a known risk factor for breast cancer. To better understand whether the human fecal and oral microbiome were associated with breast cancer risk via the regulation of estrogen metabolism, we conducted this study to investigate the associations of circulating estrogens and estrogen metabolites with the fecal and oral microbiome in postmenopausal African women. We found several associations of parent estrogens and several estrogen metabolites with the microbial communities, and multiple individual associations of estrogens and estrogen metabolites with the presence and abundance of multiple fecal and oral genera, such as fecal genera from families Lachnospiraceae and Ruminococcaceae, which have estrogen metabolizing properties. Future large, longitudinal studies to investigate the dynamic changes of the fecal and oral microbiome and estrogen relationship are needed.

Comparison of gut microbiome composition in colonic biopsies, endoscopically-collected and at-home-collected stool samples

Aim

The goal of this study is to compare microbiome composition in three different sample types in women, namely stool brought from home vs. solid stool samples obtained at the time of an unprepped sigmoidoscopy vs. biopsies of the colonic mucosa at the time of an unprepped sigmoidoscopy, using alpha- and beta-diversity metrics following bacterial 16S rRNA sequencing. The findings may have relevance to health and disease states in which bacterial metabolism has a significant impact on molecules/metabolites that are recirculated between the gut lumen and mucosa and systemic circulation, such as estrogens (as in breast cancer) or bile acids.

Methods

Concomitant at-home-collected stool, endoscopically-collected stool, and colonic biopsy samples were collected from 48 subjects (24 breast cancer, 24 control.) After 16S rRNA sequencing, an amplicon sequence variant (ASV) based approach was used to analyze the data. Alpha diversity metrics (Chao1, Pielou's Evenness, Faith PD, Shannon, and Simpson) and beta diversity metrics (Bray-Curtis, Weighted and Unweighted Unifrac) were calculated. LEfSe was used to analyze differences in the abundance of various taxa between sample types.

Results

Alpha and beta diversity metrics were significantly different between the three sample types. Biopsy samples were different than stool samples in all metrics. The highest variation in microbiome diversity was noted in the colonic biopsy samples. At-home and endoscopically-collected stool showed more similarities in count-based and weighted beta diversity metrics. There were significant differences in rare taxa and phylogenetically-diverse taxa between the two types of stool samples. Generally, there were higher levels of Proteobacteria in biopsy samples, with significantly more Actinobacteria and Firmicutes in stool (all p < 0.001, q-value < 0.05). Overall, there was a significantly higher relative abundance of Lachnospiraceae and Ruminococcaceae in stool samples (at-home collected and endoscopically-collected) and higher abundances of Tisserellaceae in biopsy samples (all p < 0.001, q-value < 0.05).

Conclusion

Our data shows that different sampling methods can impact results when looking at the composition of the gut microbiome using ASV-based approaches.

Investigating the oral microbiome in retrospective and prospective cases of prostate, colon, and breast cancer

The human microbiome has been proposed as a potentially useful biomarker for several cancers. To examine this, we made use of salivary samples from the Atlantic Partnership for Tomorrow's Health (PATH) project and Alberta's Tomorrow Project (ATP). Sample selection was divided into both a retrospective and prospective case control design examining prostate, breast, and colon cancer. In total 89 retrospective and 260 prospective cancer cases were matched to non-cancer controls and saliva samples were sequenced using 16S rRNA gene sequencing. We found no significant differences in alpha diversity. All beta diversity measures were insignificant except for unweighted UniFrac profiles in retrospective breast cancer cases and weighted UniFrac, Bray-Curtis and Robust Atchinson's distances in colon cancer after testing with age and sex adjusted MiRKAT models. Differential abundance (DA) analysis showed several taxa that were associated with previous cancer in all three groupings. Only one genus (Clostridia UCG-014) in breast cancer and one ASV (Fusobacterium periodonticum) in colon cancer was identified by more than one DA tool. In prospective cases three ASVs were associated with colon cancer, one ASV with breast cancer, and one ASV with prostate cancer. Random Forest classification showed low levels of signal in both study designs in breast and prostate cancer. Contrastingly, colon cancer did show signal in our retrospective analysis (AUC: 0.737) and in one of two prospective cohorts (AUC: 0.717). Our results indicate that it is unlikely that reliable microbial oral biomarkers for breast and prostate cancer exist.. However, further research into the oral microbiome and colon cancer could be fruitful.

TRAF3 suppression encourages B cell recruitment and prolongs survival of microbiome-intact mice with ovarian cancer

BACKGROUND

Ovarian cancer (OC) is known for exhibiting low response rates to immune checkpoint inhibitors that activate T cells. However, immunotherapies that activate B cells have not yet been extensively explored and may be a potential target, as B cells that secrete immunoglobulins have been associated with better outcomes in OC. Although the secretion of immunoglobulins is often mediated by the microbiome, it is still unclear what role they play in limiting the progression of OC.

METHODS

We conducted an in-vivo CRISPR screen of immunodeficient (NSG) and immune-intact wild type (WT) C57/BL6 mice to identify tumor-derived immune-escape mechanisms in a BRAC1- and TP53-deficient murine ID8 OC cell line (designated ITB1). To confirm gene expression and signaling pathway activation in ITB1 cells, we employed western blot, qPCR, immunofluorescent staining, and flow cytometry. Flow cytometry was also used to identify immune cell populations in the peritoneum of ITB1-bearing mice. To determine the presence of IgA-coated bacteria in the peritoneum of ITB1-bearing mice and the ascites of OC patients, we employed 16S sequencing. Testing for differences was done by using Deseq2 test and two-way ANOVA test. Sequence variants (ASVs) were produced in Qiime2 and analyzed by microeco and phyloseq R packages.

RESULTS

We identified tumor necrosis factor receptor-associated factor 3 (TRAF3) as a tumor-derived immune suppressive mediator in ITB1 cells. Knockout of TRAF3 (TRAF3KO) activated the type-I interferon pathway and increased MHC-I expression. TRAF3KO tumors exhibited a growth delay in WT mice vs. NSG mice, which was correlated with increased B cell infiltration and activation compared to ITB1 tumors. B cells were found to be involved in the progression of TRAF3KO tumors, and B-cell surface-bound and secreted IgA levels were significantly higher in the ascites of TRAF3KO tumors compared to ITB1. The presence of commensal microbiota was necessary for B-cell activation and for delaying the progression of TRAF3KO tumors in WT mice. Lastly, we observed unique profiles of IgA-coated bacteria in the ascites of OC-bearing mice or the ascites of OC patients.

CONCLUSIONS

TRAF3 is a tumor-derived immune-suppressive modulator that influences B-cell infiltration and activation, making it a potential target for enhancing anti-tumor B-cell responses in OC.

Involvement of the human microbiome in frequent cancers, current knowledge and carcinogenesis mechanisms

The human body is home to a complex microbial community, living in symbiosis. However, when an imbalance occurs, known as dysbiosis, it can lead to organic diseases such as cancers. Helicobacter pylori is commonly recognized as the causative agent of gastric cancer. Numerous studies have explored the potential role of other microorganisms in cancers. For example, the role of intestinal microbiota in the hepatocellular carcinoma formation and progression, the microbiota in breast cancer and the interaction between the microbiome and TP53 in human lung carcinogenesis. In this review, we highlight the latest findings on the microbiome involved in the most common cancers and the suggested mechanisms of carcinogenesis.

Human gut, breast, and oral microbiome in breast cancer: A systematic review and meta-analysis

Introduction

Dysbiosis characterises breast cancer through direct or indirect interference in a variety of biological pathways; therefore, specific microbial patterns and diversity may be a biomarker for the diagnosis and prognosis of breast cancer. However, there is still much to determine about the complex interplay of the gut microbiome and breast cancer.

Objective

This study aims to evaluate microbial alteration in breast cancer patients compared with control subjects, to explore intestine microbial modification from a range of different breast cancer treatments, and to identify the impact of microbiome patterns on the same treatment-receiving breast cancer patients.

Methods

A literature search was conducted using electronic databases such as PubMed, Embase, and the CENTRAL databases up to April 2021. The search was limited to adult women with breast cancer and the English language. The results were synthesised qualitatively and quantitatively using random-effects meta-analysis.

Results

A total of 33 articles from 32 studies were included in the review, representing 19 case-control, eight cohorts, and five nonrandomised intervention researches. The gut and breast bacterial species were elevated in the cases of breast tumours, a significant increase in Methylobacterium radiotolerans (p = 0.015), in compared with healthy breast tissue. Meta-analysis of different α-diversity indexes such as Shannon index (p = 0.0005), observed species (p = 0.006), and faint’s phylogenetic diversity (p &lt; 0.00001) revealed the low intestinal microbial diversity in patients with breast cancer. The microbiota abundance pattern was identified in different sample types, detection methods, menopausal status, nationality, obesity, sleep quality, and several interventions using qualitative analysis.

Conclusions

This systematic review elucidates the complex network of the microbiome, breast cancer, and therapeutic options, with the objective of providing a link for stronger research studies and towards personalised medicine to improve their quality of life.

Role of Gut Microbiota in Breast Cancer and Drug Resistance

Breast cancer is the most common malignancy in women worldwide. The cause of cancer is multifactorial. An early diagnosis and the appropriate treatment of cancer can improve the chances of survival. Recent studies have shown that breast cancer is influenced by the microbiota. Different microbial signatures have been identified in the breast microbiota, which have different patterns depending on the stage and biological subgroups. The human digestive system contains approximately 100 trillion bacteria. The gut microbiota is an emerging field of research that is associated with specific biological processes in many diseases, including cardiovascular disease, obesity, diabetes, brain disease, rheumatoid arthritis, and cancer. In this review article, we discuss the impact of the microbiota on breast cancer, with a primary focus on the gut microbiota’s regulation of the breast cancer microenvironment. Ultimately, updates on how immunotherapy can affect the breast cancer-based microbiome and further clinical trials on the breast and microbiome axis may be an important piece of the puzzle in better predicting breast cancer risk and prognosis.

Breast Cancer Survivors and Healthy Women: Could Gut Microbiota Make a Difference?-"BiotaCancerSurvivors": A Case-Control Study

In this first analysis, samples from 23 BC survivors (group 1) and 291 healthy female controls (group 2) were characterised through the V3 and V4 regions that encode the "16S rRNA" gene of each bacteria. The samples were sequenced by next-generation sequencing (NGS), and the taxonomy was identified by resorting to Kraken2 and improved with Bracken, using a curated database called 'GutHealth_DB'. The α and β-diversity analyses were used to determine the richness and evenness of the gut microbiota. A non-parametric Mann-Whitney U test was applied to assess differential abundance between both groups. The Firmicutes/Bacteroidetes (F/B) ratio was calculated using a Kruskal-Wallis chi-squared test. The α-diversity was significantly higher in group 1 (p = 0.28 × 10^-12 for the Chao index and p = 1.64 × 10^-12 for the ACE index). The Shannon index, a marker of richness and evenness, was not statistically different between the two groups (p = 0.72). The microbiota composition was different between the two groups: a null hypothesis was rejected for PERMANOVA (p = 9.99 × 10^-5) and Anosim (p = 0.04) and was not rejected for β-dispersion (p = 0.158), using Unifrac weighted distance. The relative abundance of 14 phyla, 29 classes, 25 orders, 64 families, 116 genera, and 74 species differed significantly between both groups. The F/B ratio was significantly lower in group 1 than in group 2, p < 0.001. Our study allowed us to observe significant taxonomic disparities in the two groups by testing the differences between BC survivors and healthy controls. Additional studies are needed to clarify the involved mechanisms and explore the relationship between microbiota and BC survivorship.

Gut Microbiota and Breast Cancer: The Dual Role of Microbes

Breast cancer is the most frequently diagnosed cancer and also one of the leading causes of mortality among women. The genetic and environmental factors known to date do not fully explain the risk of developing this disease. In recent years, numerous studies have highlighted the dual role of the gut microbiota in the preservation of host health and in the development of different pathologies, cancer among them. Our gut microbiota is capable of producing metabolites that protect host homeostasis but can also produce molecules with deleterious effects, which, in turn, may trigger inflammation and carcinogenesis, and even affect immunotherapy. The purpose of this review is to describe the mechanisms by which the gut microbiota may cause cancer in general, and breast cancer in particular, and to compile clinical trials that address alterations or changes in the microbiota of women with breast cancer.

Gut microbiota composition in patients with advanced malignancies experiencing immune-related adverse events

Introduction

The gut microbiota is implicated in the occurrence and severity of immune-related adverse events (irAEs), but the role it plays as well as its causal relationship with irAEs has yet to be established.

Methods

From May 2020 to August 2021, 93 fecal samples were prospectively collected from 37 patients with advanced thoracic cancers treated with anti-PD-1 therapy, and 61 samples were collected from 33 patients with various cancers developing different irAEs. 16S rDNA amplicon sequencing was performed. Antibiotic-treated mice underwent fecal microbiota transplantation (FMT) with samples from patients with and without colitic irAEs.

Results

Microbiota composition was significantly different in patients with and without irAEs (P=0.001) and with and without colitic-type irAEs (P=0.003). Bifidobacterium, Faecalibacterium, and Agathobacter were less abundant and Erysipelatoclostridium more abundant in irAE patients, while Bacteroides and Bifidobacterium were less abundant and Enterococcus more abundant in colitis-type irAE patients. Major butyrate-producing bacteria were also less abundant in patients with irAEs than those without (P=0.007) and in colitic vs. non-colitic irAE patients (P=0.018). An irAE prediction model had an AUC of 86.4% in training and 91.7% in testing. Immune-related colitis was more common in colitic-irAE-FMT (3/9) than non-irAE-FMT mice (0/9).

Conclusions

The gut microbiota is important in dictating irAE occurrence and type, especially for immune-related colitis, possibly by modulating metabolic pathways.

Intestinal IgA-Coated Bacteria in Healthy- and Altered-Microbiomes (Dysbiosis) and Predictive Value in Successful Fecal Microbiota Transplantation

IgA-coated bacteria in the gut (IgA-biome) provide a homeostatic function in healthy people through inhibition of microbial invaders and by protecting the epithelial monolayer of the gut. The laboratory methods used to detect this group of bacteria require flow cytometry and DNA sequencing (IgA-Seq). With dysbiosis (reduced diversity of the microbiome), the IgA-biome also is impaired. In the presence of enteric infection, oral vaccines, or an intestinal inflammatory disorder, the IgA-biome focuses on the pathogenic bacteria or foreign antigens, while in other chronic diseases associated with dysbiosis, the IgA-biome is reduced in capacity. Fecal microbiota transplantation (FMT), the use of fecal product from well-screened, healthy donors administered to patients with dysbiosis, has been successful in engrafting the intestine with healthy microbiota and metabolites leading to improve health. Through FMT, IgA-coated bacteria have been transferred to recipients retaining their immune coating. The IgA-biome should be evaluated in FMT studies as these mucosal-associated bacteria are more likely to be associated with successful transplantation than free luminal organisms. Studies of the microbiome pre- and post-FMT should employ metagenomic methods that identify bacteria at least at the species level to better identify organisms of interest while allowing comparisons of microbiota data between studies.

Identifying distinctive tissue and fecal microbial signatures and the tumor-promoting effects of deoxycholic acid on breast cancer

Introduction

A growing body of evidence indicates that the dysbiosis of both mammary and intestinal microbiota is associated with the initiation and progression of breast tumors. However, the microbial characteristics of patients with breast tumors vary widely across studies, and replicable biomarkers for early-stage breast tumor diagnosis remain elusive.

Methods

We demonstrate a machine learning-based method for the analysis of breast tissue and gut microbial differences among patients with benign breast disease, patients with breast cancer (BC), and healthy individuals using 16S rRNA sequence data retrieved from eight studies. QIIME 2.0 and R software (version 3.6.1) were used for consistent processing. A naive Bayes classifier was trained on the RDP v16 reference database to assign taxonomy using the Vsearch software.

Results

After re-analyzing with a total of 768 breast tissue samples and 1,311 fecal samples, we confirmed that Halomonas and Shewanella were the most representative genera of BC tissue. Bacteroides are frequently and significantly enriched in the intestines of patients with breast tumor. The areas under the curve (AUCs) of random forest models were 74.27% and 68.08% for breast carcinoma tissues and stool samples, respectively. The model was validated for effectiveness via cohort-to-cohort transfer (average AUC =0.65) and leave-one-cohort-out (average AUC = 0.66). The same BC-associated biomarker Clostridium_XlVa exists in the tissues and the gut. The results of the in-vitro experiments showed that the Clostridium-specific-related metabolite deoxycholic acid (DCA) promotes the proliferation of HER2-positive BC cells and stimulates G0/G1 phase cells to enter the S phase, which may be related to the activation of peptide-O-fucosyltransferase activity functions and the neuroactive ligand-receptor interaction pathway.

Discussion

The results of this study will improve our understanding of the microbial profile of breast tumors. Changes in the microbial population may be present in both the tissues and the gut of patients with BC, and specific markers could aid in the early diagnosis of BC. The findings from in-vitro experiments confirmed that Clostridium-specific metabolite DCA promotes the proliferation of BC cells. We propose the use of stool-based biomarkers in clinical application as a non-invasive and convenient diagnostic method.

IgA in human health and diseases: Potential regulator of commensal microbiota

Gut microbiota has extensive and tremendous impacts on human physiology and pathology. The regulation of microbiota is therefore a cardinal problem for the mutualistic relationship, as both microbial overgrowth and excessive immune reactions toward them could potentially be detrimental to host homeostasis. Growing evidence suggests that IgA, the most dominant secretory immunoglobulin in the intestine, regulates the colonization of commensal microbiota, and consequently, the microbiota-mediated intestinal and extra-intestinal diseases. In this review, we discuss the interactions between IgA and gut microbiota particularly relevant to human pathophysiology. We review current knowledge about how IgA regulates gut microbiota in humans and about the molecular mechanisms behind this interaction. We further discuss the potential role of IgA in regulating human diseases by extrapolating experimental findings, suggesting that IgA can be a future therapeutic strategy that functionally modulates gut microbiota.

Impact of intestinal dysbiosis on breast cancer metastasis and progression

Breast cancer has a high mortality rate among malignant tumors, with metastases identified as the main cause of the high mortality. Dysbiosis of the gut microbiota has become a key factor in the development, treatment, and prognosis of breast cancer. The many microorganisms that make up the gut flora have a symbiotic relationship with their host and, through the regulation of host immune responses and metabolic pathways, are involved in important physiologic activities in the human body, posing a significant risk to health. In this review, we build on the interactions between breast tissue (including tumor tissue, tissue adjacent to the tumor, and samples from healthy women) and the microbiota, then explore factors associated with metastatic breast cancer and dysbiosis of the gut flora from multiple perspectives, including enterotoxigenic Bacteroides fragilis, antibiotic use, changes in gut microbial metabolites, changes in the balance of the probiotic environment and diet. These factors highlight the existence of a complex relationship between host-breast cancer progression-gut flora. Suggesting that gut flora dysbiosis may be a host-intrinsic factor affecting breast cancer metastasis and progression not only informs our understanding of the role of microbiota dysbiosis in breast cancer development and metastasis, but also the importance of balancing gut flora dysbiosis and clinical practice.

Modulating Microbiota as a New Strategy for Breast Cancer Prevention and Treatment

Breast cancer (BC) is the most common cancer in women in the United States. There has been an increasing incidence and decreasing mortality rate of BC cases over the past several decades. Many risk factors are associated with BC, such as diet, aging, personal and family history, obesity, and some environmental factors. Recent studies have shown that healthy individuals and BC patients have different microbiota composition, indicating that microbiome is a new risk factor for BC. Gut and breast microbiota alterations are associated with BC prognosis. This review will evaluate altered microbiota populations in gut, breast tissue, and milk of BC patients, as well as mechanisms of interactions between microbiota modulation and BC. Probiotics and prebiotics are commercially available dietary supplements to alleviate side-effects of cancer therapies. They also shape the population of human gut microbiome. This review evaluates novel means of modulating microbiota by nutritional treatment with probiotics and prebiotics as emerging and promising strategies for prevention and treatment of BC. The mechanistic role of probiotic and prebiotics partially depend on alterations in estrogen metabolism, systematic immune regulation, and epigenetics regulation.

A Review of the Role of Oral Microbiome in the Development, Detection, and Management of Head and Neck Squamous Cell Cancers

The role of the microbiome in the development and propagation of head and neck squamous cell cancer (HNSCC) is largely unknown and the surrounding knowledge lags behind what has been discovered related to the microbiome and other malignancies. In this review, the authors performed a structured analysis of the available literature from several databases. The authors discuss the merits and detriments of several studies discussing the microbiome of the structures of the aerodigestive system throughout the development of HNSCC, the role of the microbiome in the development of malignancies (generally and in HNSCC) and clinical applications of the microbiome in HNSCC. Further studies will be needed to adequately describe the relationship between HNSCC and the microbiome, and to push this relationship into a space where it is clinically relevant outside of a research environment.

Gut Metabolites and Breast Cancer: The Continuum of Dysbiosis, Breast Cancer Risk, and Potential Breast Cancer Therapy

The complex association between the gut microbiome and cancer development has been an emerging field of study in recent years. The gut microbiome plays a crucial role in the overall maintenance of human health and interacts closely with the host immune system to prevent and fight infection. This review was designed to draw a comprehensive assessment and summary of recent research assessing the anticancer activity of the metabolites (produced by the gut microbiota) specifically against breast cancer. In this review, a total of 2701 articles were screened from different scientific databases (PubMed, Scopus, Embase and Web of Science) with 72 relevant articles included based on the predetermined inclusion and exclusion criteria. Metabolites produced by the gut microbial communities have been researched for their health benefits and potential anticancer activity. For instance, the short-chain fatty acid, butyrate, has been evaluated against multiple cancer types, including breast cancer, and has demonstrated anticancer potential via various molecular pathways. Similarly, nisin, a bacteriocin, has presented with a range of anticancer properties primarily against gastrointestinal cancers, with nominal evidence supporting its use against breast cancer. Comparatively, a natural purine nucleoside, inosine, though it has not been thoroughly investigated as a natural anticancer agent, has shown promise in recent studies. Additionally, recent studies demonstrated that gut microbial metabolites influence the efficacy of standard chemotherapeutics and potentially be implemented as a combination therapy. Despite the promising evidence supporting the anticancer action of gut metabolites on different cancer types, the molecular mechanisms of action of this activity are not well established, especially against breast cancer and warrant further investigation. As such, future research must prioritise determining the dose-response relationship, molecular mechanisms, and conducting animal and clinical studies to validate in vitro findings. This review also highlights the potential future directions of this field.

Gut microbiota: Role and Association with Tumorigenesis in Different Malignancies

The microbiota has been associated with different cancer and may vary from patient to patient. A specific microbial strain can alter the progression of cancer and therapeutic outcome in response to anti-cancer therapy. The variations in microbiota contributed due to the individual microbiome of the microorganism are responsible for diverse clinical outcomes. The expansion of microbiota subpopulation during dysbiosis can lead to toxin production, inducing inflammation and cancer. The microbiota can be a dual-edged sword because it can be tumor-suppressive or oncogenic in the case of the gut. The transition of cancer cells from early to late-stage also impacts the composition of the microbiota, and this alteration could change the behavior of cancer. Multi-omics platforms derived data from an individual's multi-dimensional data (DNA, mRNA, microRNA, protein, metabolite, microbiota, and microbiome), i.e., individualome, to exploit it for personalized tailored treatment for different cancers in a precise manner. A number of studies suggest the importance of microbiota and its add-in suitability to existing treatment options for different malignancies. Furthermore, in vitro, and in vivo studies and cancer clinical trials suggest that probiotics have driven modulation of gut microbiota and other sites discourage the aggressive behavior and progression of different cancers.

Roles of Secretory Immunoglobulin A in Host-Microbiota Interactions in the Gut Ecosystem

In the gastrointestinal tract (GIT), the immune system interacts with a variety of microorganisms, including pathogens as well as beneficial symbionts that perform important physiological functions for the host and are crucial to sustain intestinal homeostasis. In normal conditions, secretory immunoglobulin A (SIgA) is the principal antibody produced by B cells in the GIT mucosa. Polyreactivity provides certain SIgA molecules with the ability of binding different antigens in the bacterial surface, such as O-antigens and teichoic acids, while cross-species reactivity allows them to recognize and interact with different types of bacteria. These functions may be crucial in allowing SIgA to modulate the complex gut microbiota in an efficient manner. Several studies suggest that SIgA can help with the retention and proliferation of helpful members of the gut microbiota. Gut microbiota alterations in people with IgA deficiency include the lack of some species that are known to be normally coated by SIgA. Here, we discuss the different ways in which SIgA behaves in relation to pathogens and beneficial bacteria of the gut microbiota and how the immune system might protect and facilitate the establishment and maintenance of certain gut symbionts.

Analysis of Gut Microbiota in Patients with Breast Cancer and Benign Breast Lesions

Breast cancer (BC) and benign breast lesions (BBLs) are common diseases in women worldwide. The gut microbiota plays a vital role in regulating breast diseases' formation, progression, and therapy response. Hence, we explored the structure and function of gut microflora in patients with BC and BBLs. A cohort of 66 subjects was enrolled in the study. Twenty-six subjects had BC, 20 subjects had BBLs, and 20 matched healthy controls. High throughput 16S ribosomal RNA (16S rRNA) gene sequencing technology was used to determine the microbial community structure. Compared with healthy individuals, BC patients had significantly lower alpha diversity indices (Sobs index, p = 0.019; Chao1 index, p = 0.033). Sobs and Chao1 indices were also lower in patients with BBLs than healthy individuals, without statistical significance (p = 0.279, p = 0.314, respectively). Both unweighted and weighted UniFrac analysis showed that beta diversity differed significantly among the three groups (p = 3.376e-14, p < 0.001, respectively). Compared with healthy individuals, the levels of Porphyromonas and Peptoniphilus were higher in BC patients (p = 0.004, p = 0.007, respectively), whereas Escherichia and Lactobacillus were more enriched in the benign breast lesion group (p < 0.001, p = 0.011, respectively). Our study indicates that patients with BC and BBLs may undergo significant changes in intestinal microbiota. These findings can help elucidate the role of intestinal flora in BC and BBLs patients.

Body Microbiota and Its Relationship With Benign and Malignant Breast Tumors: A Systematic Review

Breast cancer is the most frequent type of cancer as well as one of the main causes of cancer-related mortality in women. Human microbial dysbiosis, which has been related to a range of malignancies, is one of the variables that may impact the chance of developing breast disorders. In this review, we aimed to investigate the relationship between breast cancer and benign breast tumors with dysbiosis of the microbiome at different body sites. We performed a systematic review of MEDLINE, Scopus, Ovid, and Cochrane Library to identify original articles published until July 2020 that reported studies of breast disease and microbiota. Twenty-four original articles were included in the study, which looked at the features and changes in breast, gut, urine, lymph node, and sputum microbial diversity in patients with benign and malignant breast tumors. In breast cancer, the breast tissue microbiome demonstrated changes in terms of bacterial load and diversity; in benign breast tumors, the microbiome was more similar to a malignant tumor than to normal breast tissue. Triple-negative (TNBC) and triple-positive (TPBC) types of breast cancer have a distinct microbial pattern. Moreover, in breast cancer, gut microbiota displayed changes in the compositional abundance of some bacterial families and microbial metabolites synthesis. Our review concludes that breast carcinogenesis seems to be associated with microbial dysbiosis. This information can be further explored in larger-scale studies to guide new prophylactic, diagnostic, and therapeutic measures for breast cancer.

Variations in the Gut Microbiota in Breast Cancer Occurrence and Bone Metastasis

Breast cancer is the most common cancer in women and the second most common cancer overall. Although advancements in the early diagnosis and therapy of breast cancer have occurred in recent years, the prognosis of breast cancer bone metastasis remains poor and this type of cancer is rarely cured. The gut microbiota is indispensable for internal homeostasis and regulates various biological processes. Understanding the gut microbiota profiles in normal controls (NCs), breast cancer patients with no metastasis (BNs), and breast cancer patients with bone metastasis (BMs) may shed light on the development of diagnostic and therapeutic targets for breast cancer and bone metastasis. We comprehensively analyzed the gut microbiota from NCs, BNs, and BMs and found that the community diversity decreased in the order of NCs, BNs, and BMs. Streptococcus, Campylobacter and Moraxellaceae showed higher abundances in BNs and BMs than in NCs. The lack of Megamonas and Akkermansia in the BM compared with those in the NC and BN groups was considered related to bone metastasis. Additionally, based on the distinct gut microbiota profiles, we predicted that lipid transportation and metabolism, as well as folate biosynthesis, participate in breast cancer occurrence and that steroid hormone biosynthesis influences bone metastasis. Our study demonstrated that variations in gut microbiota are associated with breast cancer occurrence and bone metastasis, providing attractive targets to develop therapeutic and diagnostic methods.

Association Between Sex Hormone Levels and Gut Microbiota Composition and Diversity-A Systematic Review

GOALS/BACKGROUND

Animal studies have highlighted how the microbiota acts in a sex-specific manner with sex hormones demonstrating an association with the composition and diversity of the microbiota. This systematic review aimed to gather the available scientific evidence to explore the association between sex hormones and gut microbiota composition and diversity, in humans.

STUDY

Four bibliographic databases were searched in July 2020 using terms related to "microbiota," "microflora," "sex hormones," "testosterone," and "estrogen." Human studies that investigated the correlation between sex hormones and the microbiota composition or diversity using next-generation sequencing were included.

RESULTS

A total of 10,468 records were screened with 13 studies included in this review. In healthy women, higher estrogen levels were found to be associated with a higher abundance of Bacteroidetes, a lower abundance of Firmicutes, the Ruminococcaceae family and increased diversity. In healthy men, raised testosterone levels positively correlated with Ruminococcus, Acinetobacter, and an increased microbial diversity. Escherichia and Shigella spp. were correlated with raised testosterone in healthy women whereas Ruminococcus spp. was negatively associated with elevated testosterone levels. Women with altered testosterone/estrogen profiles (such as in polycystic ovary syndrome), had a differing gut microbiota compared with healthy women.

CONCLUSIONS

The findings gathered highlight an association between sex hormones and the gut microbiota composition/diversity and may contribute to the sex-based variations observed in disease pathogenesis. Factors such as age and medical conditions are implicated in the associations observed and should be accounted for in future studies. As the understanding of the complex symbiotic relationship between humans and their gut microbiota increases, microbiota modulation could be an attractive option for the prevention and treatment of gastrointestinal disorders.

Metagenomic Analyses Reveal Distinct Gut Microbiota Signature for Predicting the Neoadjuvant Chemotherapy Responsiveness in Breast Cancer Patients

Background

Growing evidence supports the modulatory role of human gut microbiome on neoadjuvant chemotherapy (NAC) efficacy. However, the relationships among the gut microbiome, tumor-infiltrating lymphocytes (TILs), and NAC response for breast cancer (BC) patients remain unclear. We thus proposed this preliminary study to investigate the relationship between gut microbiome and BC patients’ responses to NAC treatment as well as underlying mechanisms.

Methods

Prior to receiving NAC, the fecal metagenome collected from 23 patients with invasive BC was analyzed. Patients were subsequently assigned to the NAC non-effectual group and the NAC effectual group based on their response to NAC. The peripheral T lymphocyte subset counts were examined by flow cytometry methods. CellMinor analysis was employed to explore the relationship between CD4 mRNA expression and the reaction of tumor cells to NAC drugs.

Results

The gut microbiomes of the NAC non-effectual group showed characteristics of low diversity with low abundances, distinct metagenomic composition with decreased butyrate-producing and indolepropionic acid-producing bacteria, and increased potential pathobionts compared with the NAC effectual group. The combination of Coprococcus, Dorea, and uncultured Ruminococcus sp. serves as signature bacteria for distinguishing NAC non-effectual group patients from the NAC effectual group. The absolute numbers of CD4⁺ and CD8⁺ TIL infiltration in tumors in the NAC non-effectual group were significantly lower than those in the effectual group. Similar findings were reported for the CD4⁺ T lymphocytes in the peripheral blood (p’s < 0.05). NAC effectual-related signature bacteria were proportional to these patients’ CD4⁺ T lymphocyte counts in peripheral blood and tumors (p’s < 0.05). CellMinor analysis showed that the CD4 mRNA expression level dramatically climbed with increased sensitivity of tumor cells to NAC drugs such as cyclophosphamide, cisplatin, and carboplatin (p’s < 0.05).

Conclusions

The composition of the gut microbial community differs between BC patients for whom NAC is effective to those that are treatment resistant. The modulation of the gut microbiota on host CD4⁺ T lymphocytes may be one critical mechanism underlying chemosensitivity and NAC pathologic response. Taken together, gut microbiota may serve as a potential biomarker for NAC response, which sheds light on novel intervention targets in the treatment of NAC non-effectual BC patients.

Oral Abundance of Actinomyces spp. in Breast Cancer Patients

OBJECTIVES

Pathophysiology of medication-related osteonecrosis of the jaw (MRONJ) is still unclear and disease development is associated with adverse reaction of bisphosphonates and denosumab, and Actinomyces spp. as well. In this study we evaluated the abundance of Actinomyces spp. in breast cancer patients undergoing chemotherapy compared to healthy controls.

METHODS

Oropharyngeal samples were collected from treatment naive early-stage breast cancer patients, who were scheduled for standard of care therapy (eight samples throughout chemotherapy, one prior to radiotherapy and one after a year of start), as well as from healthy controls at matched timepoints. We quantified Actinomyces spp. in the samples with a highly sensitive and specific qPCR.

RESULTS

Twenty-one patients and 16 healthy subjects were enrolled. 48% of patients suffered from ER-positive/PR-positive or -negative/HER2-negative disease, 38% were HER2-positive and 14% were triple-negative. Comparison of Actinomyces spp. loads in cancer patients and healthy controls did not reveal significant difference. Fluctuations on bacterial quantity was observed in both groups over time. Tumor receptor status or different chemotherapy schemes of patients were not correlated with a particular pattern on abundance of Actinomyces spp.

CONCLUSIONS

We suggest that Actinomyces spp. are not the initiative factor in MRONJ development. These bacteria are not altered in abundance during chemotherapy, but they behave opportunistic when there is a bone disruption in the oropharynx in the first place caused by antiresorptive drugs or dental trauma and proliferate in their new niche. Thus, Actinomyces spp. play a latter role in MRONJ development, rather than a primary causative one.

Intestinal Microbiota in Postmenopausal Breast Cancer Patients and Controls

Simple Summary

Besides the already known factors that increase the risk of breast cancer, like hormonal treatment, heredity, and obesity, growing evidence exists that intestinal microbiota can influence breast cancer carcinogenesis. Current clinical information into the role of the intestinal microbiota in breast cancer patients is limited. This study aimed to see whether there are differences in intestinal microbiota richness, diversity, and composition between oestrogen receptor positive breast cancer patients and controls. We concluded that the intestinal microbiota richness, diversity, and composition were not different between breast cancer patients and postmenopausal controls. An increased relative abundance of Dialister and Veillonellaceae was observed in breast cancer patients scheduled for adjuvant treatment, which might be caused by a relative decrease in other bacteria due to surgery associated factors rather than an absolute increase. For future studies, we strongly advise a more homogeneous group of breast cancer patients of preferably treatment-naive patients.

Abstract

Background: Previous preclinical and clinical research has investigated the role of intestinal microbiota in carcinogenesis. Growing evidence exists that intestinal microbiota can influence breast cancer carcinogenesis. However, the role of intestinal microbiota in breast cancer needs to be further investigated. This study aimed to identify the microbiota differences between postmenopausal breast cancer patients and controls. Patients and methods: This prospective cohort study compared the intestinal microbiota richness, diversity, and composition in postmenopausal histologically proven ER+/HER2- breast cancer patients and postmenopausal controls. Patients scheduled for (neo)adjuvant adriamycin, cyclophosphamide (AC), and docetaxel (D), or endocrine therapy (tamoxifen) were prospectively enrolled in a multicentre cohort study in the Netherlands. Patients collected a faecal sample and completed a questionnaire before starting systemic cancer treatment. Controls, enrolled from the National Dutch Breast Cancer Screening Programme, also collected a faecal sample and completed a questionnaire. Intestinal microbiota was analysed by amplicon sequencing of the 16S rRNA V4 gene region. Results: In total, 81 postmenopausal ER+/HER2- breast cancer patients and 67 postmenopausal controls were included, resulting in 148 faecal samples. Observed species richness, Shannon index, and overall microbial community structure were not significantly different between breast cancer patients and controls. There was a significant difference in overall microbial community structure between breast cancer patients scheduled for adjuvant treatment, neoadjuvant treatment, and controls at the phylum (p = 0.042) and genus levels (p = 0.015). Dialister (p = 0.001) and its corresponding family Veillonellaceae (p = 0.001) were higher in patients scheduled for adjuvant treatment, compared to patients scheduled for neoadjuvant treatment. Additional sensitivity analysis to correct for the potential confounding effect of prophylactic antibiotic use, indicated no differences in microbial community structure between patients scheduled for neoadjuvant systemic treatment, adjuvant systemic treatment, and controls at the phylum (p = 0.471) and genus levels (p = 0.124). Conclusions: Intestinal microbiota richness, diversity, and composition are not different between postmenopausal breast cancer patients and controls. The increased relative abundance of Dialister and Veillonellaceae was observed in breast cancer patients scheduled for adjuvant treatment, which might be caused by a relative decrease in other bacteria due to prophylactic antibiotic administration rather than an absolute increase.

Pro- and Anti- Effects of Immunoglobulin A- Producing B Cell in Tumors and Its Triggers

B cells are well known as key mediators of humoral immune responses via the production of antibodies. Immunoglobulin A (IgA) is the most abundantly produced antibody isotype and provides the first line of immune protection at mucosal surfaces. However, IgA has long been a divisive molecule with respect to tumor progression. IgA exerts anti- or pro-tumor effect in different tumor types. In this review, we summarize emerging evidence regarding the production and effects of IgA and IgA⁺ cells in the tumor microenvironment (TME). Moreover, we discuss that the TME cytokines, host diet, microbiome, and metabolites play a pivotal role in controlling the class-switch recombination (CSR) of IgA. The analysis of intratumoral Ig repertoires and determination of metabolites that influence CSR may help establish novel therapeutic targets for the treatment of cancers.