The Microbiome-Estrogen Connection and Breast Cancer Risk

Association between Antibiotic Use and Subsequent Risk of Breast Cancer: A Nationwide Retrospective Cohort Study in South Korea

Several studies have revealed a possible association between antibiotic use and breast cancer in the Western population of women. However, its association with the Asian population remains unclear. Data utilized in this nationwide population-based retrospective cohort study were obtained from the Korean National Health Insurance Service database. The study population consisted of 4,097,812 women who were followed up from January 1, 2007, to December 31, 2019. Cox proportional hazards regression was utilized to calculate adjusted hazard ratio (aHR) and 95% confidence interval (CI) for the risk of breast cancer according to cumulative days of antibiotic use and the number of antibiotic classes used. It was discovered that women who used antibiotics for more than 365 days had a higher risk of breast cancer (aHR, 1.15; 95% CI, 1.09-1.21) in comparison with those who did not use antibiotics. In addition, an association was found among women who used five or more classes of antibiotics, showing a higher risk of breast cancer (aHR, 1.11; 95% CI, 1.05-1.17) compared with nonusers. Furthermore, compared with antibiotic nonusers, only users of cephalosporins (aHR, 1.09; 95% CI, 1.02-1.17) and lincosamides (aHR, 1.70; 95% CI, 1.20-2.42) had a higher risk of breast cancer. These findings support epidemiologic evidence that long-term use of antibiotics may be associated with a higher risk of breast cancer. This underscores the need for further studies to address the potential for residual confounding, confirm causation, and elucidate the underlying mechanisms. Prevention Relevance: This study found a probable duration-dependent association between antibiotic prescriptions and breast cancer risk. The findings indicate that long-term antibiotic use could be associated with an increased risk of breast cancer and highlight the need for further research to confirm causality and mechanisms.

Endoscopic surgery affects the gut microbiota and its metabolism in breast cancer patients

Background

Despite the advantages of endoscopic surgery in reducing trauma and enhancing recovery for breast cancer patients, its impact on gut microbiota, which is crucial for health and estrogen metabolism, remains unclear. Further investigation is necessary to fully understand this impact and its implications.

Materials and methods

Between June and December 2022, fecal samples were collected from 20 patients who underwent endoscopic surgery. The gut microbiota composition was determined using 16S rRNA sequencing, while the metabolites were analyzed through liquid chromatography-tandem mass spectrometry (LC-MS/MS). Bioinformatics and statistical analyses were employed to identify significant alterations in microbial taxa abundance and to assess intergroup differences. These analyses included t-tests for pairwise comparisons, one-way ANOVA for multiple group comparisons, and chi-square tests for categorical data analysis.

Results

Endoscopic surgery in breast cancer patients subtly changed gut microbiota diversity and composition. Post-surgery, there was a reduction in Lachnospiraceae, Monoglobaceae and Firmicutes to Bacteroides ratios. Shifts in metabolites were also observed, the changed metabolites impacted pathways such as primary bile biosynthesis and Ascorbate and aldarate metabolism, with PE(PGD1/18:1(9Z)) identified as a key differential metabolite that increased post-surgery. Azasetron, tyramine glucuronide, DL-DOPA, phthalide, acetophenazine, aciclovir, creatinine bicarbonate, and 4-oxo-L-proline being associated with distinct bacterial taxa.

Conclusion

Breast cancer patients undergoing endoscopic surgery experience a shift in their gut microbiota and metabolic profiles. Therefore, postoperative management, with a particular focus on the adjustment of the gut microbiota, is crucial for enhancing patient recovery and health outcomes.

Metabolites in the Dance: Deciphering Gut-Microbiota-Mediated Metabolic Reprogramming of the Breast Tumor Microenvironment

Breast cancer (BC), a major cause of death among women worldwide, has traditionally been linked to genetic and environmental factors. However, emerging research highlights the gut microbiome's significant role in shaping BC development, progression, and treatment outcomes. This review explores the intricate relationship between the gut microbiota and the breast tumor microenvironment, emphasizing how these microbes influence immune responses, inflammation, and metabolic pathways. Certain bacterial species in the gut either contribute to or hinder BC progression by producing metabolites that affect hormone metabolism, immune system pathways, and cellular signaling. An imbalance in gut bacteria, known as dysbiosis, has been associated with a heightened risk of BC, with metabolites like short-chain fatty acids (SCFAs) and enzymes such as β-glucuronidase playing key roles in this process. Additionally, the gut microbiota can impact the effectiveness of chemotherapy, as certain bacteria can degrade drugs like gemcitabine and irinotecan, leading to reduced treatment efficacy. Understanding the complex interactions between gut bacteria and BC may pave the way for innovative treatment approaches, including personalized microbiome-targeted therapies, such as probiotics and fecal microbiota transplants, offering new hope for more effective prevention, diagnosis, and treatment of BC.

Emerging Role of Gut Microbiota in Breast Cancer Development and Its Implications in Treatment

Background: 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. Emerging evidence indicates that the gut microbiota affects the response to anticancer therapies by modulating the host immune system. Recent studies have explained a high correlation between the gut microbiota and breast cancer: dysbiosis in breast cancer may regulate the systemic inflammatory response, hormone metabolism, immune response, and the tumor microenvironment. Some of the gut bacteria are related to estrogen metabolism, which may increase or decrease the risk of breast cancer by changing the number of hormones. Further, the gut microbiota has been seen to modulate the immune system in respect of its ability to protect against and treat cancers, with a specific focus on hormone receptor-positive breast cancer. Probiotics and other therapies claiming to control the gut microbiome by bacterial means might be useful in the prevention, or even in the treatment, of breast cancer. Conclusions: The present review underlines the various aspects of gut microbiota in breast cancer risk and its clinical application, warranting research on individualized microbiome-modulated therapeutic approaches to breast cancer treatment.

Bacterial live therapeutics for human diseases

The genomic revolution has fueled rapid progress in synthetic and systems biology, opening up new possibilities for using live biotherapeutic products (LBP) to treat, attenuate or prevent human diseases. Among LBP, bacteria-based therapies are particularly promising due to their ability to colonize diverse human tissues, modulate the immune system and secrete or deliver complex biological products. These bacterial LBP include engineered pathogenic species designed to target specific diseases, and microbiota species that promote microbial balance and immune system homeostasis, either through local administration or the gut-body axes. This review focuses on recent advancements in preclinical and clinical trials of bacteria-based LBP, highlighting both on-site and long-reaching strategies.

The bacterial microbiome and cancer: development, diagnosis, treatment, and future directions

The term "microbiome" refers to the collection of bacterial species that reside in the human body's tissues. Sometimes, it is used to refer to all microbial entities (bacteria, viruses, fungi, and others) which colonize the human body. It is now generally acknowledged that the microbiome plays a critical role in the host's physiological processes and general well-being. Changes in the structure and/or function of the microbiome (dysbiosis) are linked to the development of many diseases including cancer. The claim that because of their negatively charged membrane, cancer cells are more vulnerable to some bacteria than normal cells and that is how the link between these bacteria and cancer evolved has been refuted. Furthermore, the relationship between the microbiome and cancer is more evident in the emerging field of cancer immunotherapy. In this narrative review, we detailed the correlation between the presence/absence of specific bacterial species and the development, diagnosis, prognosis, and treatment of some types of cancer including colorectal, lung, breast, and prostate cancer. In addition, we discussed the mechanisms of microbiome-cancer interactions including genotoxin production, the role of free radicals, modification of signaling pathways in host cells, immune modulation, and modulation of drug metabolism by microbiome. Future directions and clinical application of microbiome in the early detection, prognosis, and treatment of cancer emphasizing on the role of fecal transplantation, probiotics, prebiotics, and microbiome biomarkers were also considered.

Breast tumor microbiome regulates anti-tumor immunity and T cell-associated metabolites

Background

Breast cancer, the most common cancer type among women, was recently found to contain a specific tumor microbiome, but its impact on host biology remains unclear. CD8+ tumor-infiltrating lymphocytes (TILs) are pivotal effectors of anti-tumor immunity that influence cancer prognosis and response to therapy. This study aims to elucidate interactions between CD8+ TILs and the breast tumor microbiome and metabolites, as well as how the breast tumor microbiome may affect the tumor metabolome.

Methods

We investigated the interplay among CD8+ TILs, the tumor microbiome, and the metabolome in a cohort of 46 breast cancer patients with mixed subtypes (Cohort A). We characterized the tumor metabolome by mass spectrometry and CD8+ TILs by immunohistochemistry. Microbiome composition and T cell gene transcript levels were obtained from data from our previous study, which utilized 16S rRNA gene sequencing and a targeted mRNA expression panel. To examine interactions between intratumoral Staphylococcus and specific breast cancer subtypes, we analyzed RNA sequencing data from an independent cohort of 370 breast cancer patients (Cohort B). We explored the functions of the tumor microbiome using mouse models of triple-negative breast cancer (TNBC).

Results

In tumors from Cohort A, the relative abundance of Staphylococcus positively correlated with the expression of T cell activation genes. The abundances of multiple metabolites exhibited significant correlations with CD8+ TILs, of which NADH, γ-glutamyltryptophan, and γ-glutamylglutamate displayed differential abundance in Staphylococcus-positive versus Staphylococcus-negative breast tumors. In a larger breast cancer cohort (Cohort B), we observed positive correlations between tumoral Staphylococcus and CD8+ TIL activity exclusively in TNBC. Preclinical experiments demonstrated that intratumoral administration of S. aureus, the predominant species of Staphylococcus in human breast tumors, resulted in a depletion of total NAD metabolites, and reduced the growth of TNBC tumors by activating CD8+ TILs.

Conclusions

We identified specific metabolites and microbial taxa associated with CD8+ TILs, delineated interactions between the breast tumor microbiome and metabolome, and demonstrated that intratumoral Staphylococcus influences anti-tumor immunity and TIL-associated metabolites. These findings highlight the role of low-biomass microbes in tumor tissues and provide potential biomarkers and therapeutic agents for breast cancer immunotherapy that merit further investigation.

Interaction between young fecal transplantation and perfluorobutanesulfonate endocrine disrupting toxicity in aged recipients: An estrobolome perspective

Transplanting young feces into the aged was found to effectively counteract the endocrine disrupting effects of perfluorobutanesulfonate (PFBS) pollutant, showing promise in the maintenance of healthy aging. However, the interactive mechanisms between young fecal transplantation and PFBS endocrine disruption during aging remain unclear. In this follow-up study, aged zebrafish were administered young donor feces and then exposed to environmentally relevant concentrations of PFBS (0 and 100 μg/L). Alterations in the holistic estrobolome along gut-liver axis were investigated. The results showed that PFBS singular exposure significantly increased blood estradiol concentration in the aged, inducing an estrogenic activity. Concentrations of other estrogen forms, including estrone and estriol, were also disrupted by PFBS. Interestingly, young fecal transplant effectively mitigated the estrogenic toxicity of PFBS and largely restored estrogen equilibrium. After PFBS exposure, the transcriptions of estrogen metabolic genes were consistently upregulated in aged livers, causing the accumulation of 2-methoxyestradiol-3-methylether metabolite. In contrast, aged livers coexposed to young fecal transplant and PFBS enhanced the glucuronidation process, successfully facilitating the elimination and detoxification of estrogen metabolites. In aged gut, PFBS exposure inhibited β-glucuronidase enzyme activity, implying the suppression of estrogen deconjugation and recycle. However, in the combined group, β-glucuronidase activity was significantly stimulated, thus reestablishing estrobolome dynamics. Overall, current findings provide mechanistic insights into the antagonistic interaction between young fecal transplant and PFBS on reproductive endocrinology. Gut microbiota manipulation appears appealing to maintain healthy aging progression albeit the interruption of environmental xenobiotics.

The impact of intestinal and mammary microbiomes on breast cancer development: A review on the microbiota and oestrobolome roles in tumour microenvironments

Microbiota affects carcinogenesis by altering energy equilibrium, increasing fat mass, synthesizing small signaling molecules, and formulating and regulating immune response and indigestible food ingredient, xenobiotic, and pharmaceutical compound metabolism. The intestinal microbiome can moderate oestrogen and other steroid hormone metabolisms, and secrete bioactive metabolites that are important for tumour microenvironment. Specifically, the breast tissue microbiome could become altered and lead to breast cancer development. The study of oestrobolome, the microbiomic component that metabolizes oestrogens, can contribute to better breast cancer understanding and subsequent treatment. Investigating oestrobolome-related oestrogen metabolism mechanisms in immune system regulation can shed light on how intestinal microorganisms regulate tumour microenvironment. Intestinal and regional breast microbiomes can determine treatment lines and serve as possible biomarkers for breast cancer. The aim of this study is to summarise current evidence on the role of microbiome in breast cancer progression with particular interest in therapeutic and diagnostic implementation.

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.

Nutrition Intervention and Microbiome Modulation in the Management of Breast Cancer

Breast cancer (BC) is one of the most common cancers worldwide and a leading cause of cancer-related deaths among women. The escalating incidence of BC underscores the necessity of multi-level treatment. BC is a complex and heterogeneous disease involving many genetic, lifestyle, and environmental factors. Growing evidence suggests that nutrition intervention is an evolving effective prevention and treatment strategy for BC. In addition, the human microbiota, particularly the gut microbiota, is now widely recognized as a significant player contributing to health or disease status. It is also associated with the risk and development of BC. This review will focus on nutrition intervention in BC, including dietary patterns, bioactive compounds, and nutrients that affect BC prevention and therapeutic responses in both animal and human studies. Additionally, this paper examines the impacts of these nutrition interventions on modulating the composition and functionality of the gut microbiome, highlighting the microbiome-mediated mechanisms in BC. The combination treatment of nutrition factors and microbes is also discussed. Insights from this review paper emphasize the necessity of comprehensive BC management that focuses on the nutrition-microbiome axis.

Elucidating the Intricate Roles of Gut and Breast Microbiomes in Breast Cancer Metastasis to the Bone

BACKGROUND

Breast cancer is the most predominant and heterogeneous cancer in women. Moreover, breast cancer has a high prevalence to metastasize to distant organs, such as the brain, lungs, and bones. Patients with breast cancer metastasis to the bones have poor overall and relapse-free survival. Moreover, treatment using chemotherapy and immunotherapy is ineffective in preventing or reducing cancer metastasis.

RECENT FINDINGS

Microorganisms residing in the gut and breast, termed as the resident microbiome, have a significant influence on the formation and progression of breast cancer. Recent studies have identified some microorganisms that induce breast cancer metastasis to the bone. These organisms utilize multiple mechanisms, including induction of epithelial-mesenchymal transition, steroid hormone metabolism, immune modification, bone remodeling, and secretion of microbial products that alter tumor microenvironment, and enhance propensity of breast cancer cells to metastasize. However, their involvement makes these microorganisms suitable as novel therapeutic targets. Thus, studies are underway to prevent and reduce breast cancer metastasis to distant organs, including the bone, using chemotherapeutic or immunotherapeutic drugs, along with probiotics, antibiotics or fecal microbiota transplantation.

CONCLUSIONS

The present review describes association of gut and breast microbiomes with bone metastases. We have elaborated on the mechanisms utilized by breast and gut microbiomes that induce breast cancer metastasis, especially to the bone. The review also highlights the current treatment options that may target both the microbiomes for preventing or reducing breast cancer metastases. Finally, we have specified the necessity of maintaining a diverse gut microbiome to prevent dysbiosis, which otherwise may induce breast carcinogenesis and metastasis especially to the bone. The review may facilitate more detailed investigations of the causal associations between these microbiomes and bone metastases. Moreover, the potential treatment options described in the review may promote discussions and research on the modes to improve survival of patients with breast cancer by targeting the gut and breast microbiomes.

The Impact of Gestational Diabetes Mellitus (GDM) on the Development and Composition of the Neonatal Gut Microbiota: A Systematic Review

Gestational diabetes mellitus (GDM) is an important health issue, as it is connected with adverse effects to the mother as well as the fetus. A factor of essence for the pathology of this disorder is the gut microbiota, which seems to have an impact on the development and course of GDM. The role of the gut microbiota on maternal reproductive health and all the changes that happen during pregnancy as well as during the neonatal period is of high interest. The correct establishment and maturation of the gut microbiota is of high importance for the development of basic biological systems. The aim of this study is to provide a systematic review of the literature on the effect of GDM on the gut microbiota of neonates, as well as possible links to morbidity and mortality of neonates born to mothers with GDM. Systematic research took place in databases including PubMed and Scopus until June 2024. Data that involved demographics, methodology, and changes to the microbiota were derived and divided based on patients with exposure to or with GDM. The research conducted on online databases revealed 316 studies, of which only 16 met all the criteria and were included in this review. Research from the studies showed great heterogeneity and varying findings at the level of changes in α and β diversity and enrichment or depletion in phylum, gene, species, and operational taxonomic units in the neonatal gut microbiota of infants born to mothers with GDM. The ways in which the microbiota of neonates and infants are altered due to GDM remain largely unclear and require further investigation. Future studies are needed to explore and clarify these mechanisms.

Dual Regulation Mechanism of Obesity: DNA Methylation and Intestinal Flora

Obesity is a multifactorial chronic inflammatory metabolic disorder, with pathogenesis influenced by genetic and non-genetic factors such as environment and diet. Intestinal microbes and their metabolites play significant roles in the occurrence and development of obesity by regulating energy metabolism, inducing chronic inflammation, and impacting intestinal hormone secretion. Epigenetics, which involves the regulation of host gene expression without changing the nucleotide sequence, provides an exact direction for us to understand how the environment, lifestyle factors, and other risk factors contribute to obesity. DNA methylation, as the most common epigenetic modification, is involved in the pathogenesis of various metabolic diseases. The epigenetic modification of the host is induced or regulated by the intestinal microbiota and their metabolites, linking the dynamic interaction between the microbiota and the host genome. In this review, we examined recent advancements in research, focusing on the involvement of intestinal microbiota and DNA methylation in the etiology and progression of obesity, as well as potential interactions between the two factors, providing novel perspectives and avenues for further elucidating the pathogenesis, prevention, and treatment of obesity.

17β-estradiol in colorectal cancer: friend or foe?

Colorectal cancer (CRC) is a common gastrointestinal malignancy with higher incidence and mortality rates in men compared to women, potentially due to the effects of estrogen signaling. There is substantial evidence supporting the significant role of 17β-Estradiol (E2) in reducing CRC risk in females, although this perspective remains debated. E2 has been demonstrated to inhibit CRC cell proliferation and migration at the cellular level by enhancing DNA mismatch repair, modulating key gene expression, triggering cell cycle arrest, and reducing activity of migration factors. Furthermore, E2 contributes to promote a tumor microenvironment unfavorable for CRC growth by stimulating ERβ expression, reducing inflammatory responses, reversing immunosuppression, and altering the gut microbiome composition. Conversely, under conditions of high oxidative stress, hypoxia, and nutritional deficiencies, E2 may facilitate CRC development through GPER-mediated non-genomic signaling. E2's influence on CRC involves the genomic and non-genomic signals mediated by ERβ and GPER, respectively, leading to its dual roles in anticancer activity and carcinogenesis. This review aims to summarize the potential mechanisms by which E2 directly or indirectly impacts CRC development, providing insights into the phenomenon of sexual dimorphism in CRC and suggesting potential strategies for prevention and treatment.

Drinking Water Microbiota, Entero-Mammary Pathways, and Breast Cancer: Focus on Nontuberculous Mycobacteria

The prospect of drinking water serving as a conduit for gut bacteria, artificially selected by disinfection strategies and a lack of monitoring at the point of use, is concerning. Certain opportunistic pathogens, notably some nontuberculous mycobacteria (NTM), often exceed coliform bacteria levels in drinking water, posing safety risks. NTM and other microbiota resist chlorination and thrive in plumbing systems. When inhaled, opportunistic NTM can infect the lungs of immunocompromised or chronically ill patients and the elderly, primarily postmenopausal women. When ingested with drinking water, NTM often survive stomach acidity, reach the intestines, and migrate to other organs using immune cells as vehicles, potentially colonizing tumor tissue, including in breast cancer. The link between the microbiome and cancer is not new, yet the recognition of intratumoral microbiomes is a recent development. Breast cancer risk rises with age, and NTM infections have emerged as a concern among breast cancer patients. In addition to studies hinting at a potential association between chronic NTM infections and lung cancer, NTM have also been detected in breast tumors at levels higher than normal adjacent tissue. Evaluating the risks of continued ingestion of contaminated drinking water is paramount, especially given the ability of various bacteria to migrate from the gut to breast tissue via entero-mammary pathways. This underscores a pressing need to revise water safety monitoring guidelines and delve into hormonal factors, including addressing the disproportionate impact of NTM infections and breast cancer on women and examining the potential health risks posed by the cryptic and unchecked microbiota from drinking water.

Blood Microbiota and Its Products: Mechanisms of Interference with Host Cells and Clinical Outcomes

In healthy conditions, blood was considered a sterile environment until the development of new analytical approaches that allowed for the detection of circulating bacterial ribosomal DNA. Currently, debate exists on the origin of the blood microbiota. According to advanced research using dark field microscopy, fluorescent in situ hybridization, flow cytometry, and electron microscopy, so-called microbiota have been detected in the blood. Conversely, others have reported no evidence of a common blood microbiota. Then, it was hypothesized that blood microbiota may derive from distant sites, e.g., the gut or external contamination of blood samples. Alteration of the blood microbiota's equilibrium may lead to dysbiosis and, in certain cases, disease. Cardiovascular, respiratory, hepatic, kidney, neoplastic, and immune diseases have been associated with the presence of Gram-positive and Gram-negative bacteria and/or their products in the blood. For instance, lipopolysaccharides (LPSs) and endotoxins may contribute to tissue damage, fueling chronic inflammation. Blood bacteria can interact with immune cells, especially with monocytes that engulf microorganisms and T lymphocytes via spontaneous binding to their membranes. Moreover, LPSs, extracellular vesicles, and outer membrane vesicles interact with red blood cells and immune cells, reaching distant organs. This review aims to describe the composition of blood microbiota in healthy individuals and those with disease conditions. Furthermore, special emphasis is placed on the interaction of blood microbiota with host cells to better understand disease mechanisms.

Bioinformatic analysis and experimental validation of six cuproptosis-associated genes as a prognostic signature of breast cancer

Background

Breast carcinoma (BRCA) is a life-threatening malignancy in women and shows a poor prognosis. Cuproptosis is a novel mode of cell death but its relationship with BRCA is unclear. This study attempted to develop a cuproptosis-relevant prognostic gene signature for BRCA.

Methods

Cuproptosis-relevant subtypes of BRCA were obtained by consensus clustering. Differential expression analysis was implemented using the 'limma' package. Univariate Cox and multivariate Cox analyses were performed to determine a cuproptosis-relevant prognostic gene signature. The signature was constructed and validated in distinct datasets. Gene set variation analysis (GSVA) and gene set enrichment analysis (GSEA) were also conducted using the prognostic signature to uncover the underlying molecular mechanisms. ESTIMATE and CIBERSORT algorithms were applied to probe the linkage between the gene signature and tumor microenvironment (TME). Immunotherapy responsiveness was assessed using the Tumor Immune Dysfunction and Exclusion (TIDE) web tool. Real-time quantitative PCR (RT-qPCR) was performed to detect the expressions of cuproptosis-relevant prognostic genes in breast cancer cell lines.

Results

Thirty-eight cuproptosis-associated differentially expressed genes (DEGs) in BRCA were mined by consensus clustering and differential expression analysis. Based on univariate Cox and multivariate Cox analyses, six cuproptosis-relevant prognostic genes, namely SAA1, KRT17, VAV3, IGHG1, TFF1, and CLEC3A, were mined to establish a corresponding signature. The signature was validated using external validation sets. GSVA and GSEA showed that multiple cell cycle-linked and immune-related pathways along with biological processes were associated with the signature. The results ESTIMATE and CIBERSORT analyses revealed significantly different TMEs between the two Cusig score subgroups. Finally, RT-qPCR analysis of cell lines further confirmed the expressional trends of SAA1, KRT17, IGHG1, and CLEC3A.

Conclusion

Taken together, we constructed a signature for projecting the overall survival of BRCA patients and our findings authenticated the cuproptosis-relevant prognostic genes, which are expected to provide a basis for developing prognostic molecular biomarkers and an in-depth understanding of the relationship between cuproptosis and 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.

Epigenetics, Microbiota, and Breast Cancer: A Systematic Review

Breast cancer is the most frequently diagnosed cancer in women worldwide. According to recent studies, alterations in the microbiota and epigenetic modulations are risk factors for this disease. This systematic review aims to determine the possible associations between the intestinal and mammary microbial populations, epigenetic modifications, and breast cancer. To achieve this objective, we conducted a literature search in the PubMed, Web of Science, and Science Direct databases following the PRISMA guidelines. Although no results are yet available in humans, studies in mice suggest a protective effect of maternal dietary interventions with bioactive compounds on the development of breast tumors in offspring. These dietary interventions also modified the gut microbiota, increasing the relative abundance of short-chain fatty acid-producing taxa and preventing mammary carcinogenesis. In addition, short-chain fatty acids produced by the microbiota act as epigenetic modulators. Furthermore, some authors indicate that stress alters the gut microbiota, promoting breast tumor growth through epigenetic and gene expression changes in the breast tumor microenvironment. Taken together, these findings show the ability of epigenetic modifications and alterations of the microbiota associated with environmental factors to modulate the development, aggressiveness, and progression of breast cancer.

The interactions between traditional Chinese medicine and gut microbiota in cancers: Current status and future perspectives

The gut microbiota, known as the "forgotten organ" and "human second genome," comprises a complex microecosystem. It significantly influences the development of various tumors, including colorectal, liver, stomach, breast, and lung cancers, through both direct and indirect mechanisms. These mechanisms include the "gut-liver" axis, the "lung-intestine" axis, and interactions with the immune system. The intestinal flora exhibits dual roles in cancer, both promoting and suppressing its progression. Traditional Chinese medicine (TCM) can alter cancer progression by regulating the intestinal flora. It modifies the intestinal flora's composition and structure, along with the levels of endogenous metabolites, thus affecting the intestinal barrier, immune system, and overall body metabolism. These actions contribute to TCM's significant antitumor effects. Moreover, the gut microbiota metabolizes TCM components, enhancing their antitumor properties. Therefore, exploring the interaction between TCM and the intestinal flora offers a novel perspective in understanding TCM's antitumor mechanisms. This paper succinctly reviews the association between gut flora and the development of tumors, including colorectal, liver, gastric, breast, and lung cancers. It further examines current research on the interaction between TCM and intestinal flora, with a focus on its antitumor efficacy. It identifies limitations in existing studies and suggests recommendations, providing insights into antitumor drug research and exploring TCM's antitumor effectiveness. Additionally, this paper aims to guide future research on TCM and the gut microbiota in antitumor studies.

Mapping the function of MicroRNAs as a critical regulator of tumor-immune cell communication in breast cancer and potential treatment strategies

Among women, breast cancer ranks as the most prevalent form of cancer, and the presence of metastases significantly reduces prognosis and diminishes overall survival rates. Gaining insights into the biological mechanisms governing the conversion of cancer cells, their subsequent spread to other areas of the body, and the immune system's monitoring of tumor growth will contribute to the advancement of more efficient and targeted therapies. MicroRNAs (miRNAs) play a critical role in the interaction between tumor cells and immune cells, facilitating tumor cells' evasion of the immune system and promoting cancer progression. Additionally, miRNAs also influence metastasis formation, including the establishment of metastatic sites and the transformation of tumor cells into migratory phenotypes. Specifically, dysregulated expression of these genes has been associated with abnormal expression of oncogenes and tumor suppressor genes, thereby facilitating tumor development. This study aims to provide a concise overview of the significance and function of miRNAs in breast cancer, focusing on their involvement as tumor suppressors in the antitumor immune response and as oncogenes in metastasis formation. Furthermore, miRNAs hold tremendous potential as targets for gene therapy due to their ability to modulate specific pathways that can either promote or suppress carcinogenesis. This perspective highlights the latest strategies developed for miRNA-based therapies.

Fusobacterium nucleatum: An Overview of Evidence, Demi-Decadal Trends, and Its Role in Adverse Pregnancy Outcomes and Various Gynecological Diseases, including Cancers

Gynecological and obstetric infectious diseases are crucial to women's health. There is growing evidence that links the presence of Fusobacterium nucleatum (F. nucleatum), an anaerobic oral commensal and potential periodontal pathogen, to the development and progression of various human diseases, including cancers. While the role of this opportunistic oral pathogen has been extensively studied in colorectal cancer in recent years, research on its epidemiological evidence and mechanistic link to gynecological diseases (GDs) is still ongoing. Thus, the present review, which is the first of its kind, aims to undertake a comprehensive and critical reappraisal of F. nucleatum, including the genetics and mechanistic role in promoting adverse pregnancy outcomes (APOs) and various GDs, including cancers. Additionally, this review discusses new conceptual advances that link the immunomodulatory role of F. nucleatum to the development and progression of breast, ovarian, endometrial, and cervical carcinomas through the activation of various direct and indirect signaling pathways. However, further studies are needed to explore and elucidate the highly dynamic process of host-F. nucleatum interactions and discover new pathways, which will pave the way for the development of better preventive and therapeutic strategies against this pathobiont.

Activation of the YY1-UGT2B7 Axis Promotes Mammary Estrogen Homeostasis Dysregulation and Exacerbates Breast Tumor Metastasis

Metastasis is the most common pathway of cancer death. The lack of effective predictors of breast cancer metastasis is a pressing issue in clinical practice. Therefore, exploring the mechanism of breast cancer metastasis to uncover reliable predictors is very important for the clinical treatment of breast cancer patients. In this study, tandem mass tag quantitative proteomics technology was used to detect protein content in primary breast tumor tissue samples from patients with metastatic and nonmetastatic breast cancer at diagnosis. We found that the high expression of yin-yang 1(YY1) is strongly associated with poor prognosis in high-grade breast cancer. YY1 expression was detected in both clinical tumor tissue samples and tumor tissue samples from mammary-specific polyomavirus middle T antigen overexpression mouse model mice. We demonstrated that upregulation of YY1 expression was closely associated with breast cancer metastasis and that high YY1 expression could promote the migratory invasive ability of breast cancer cells. Mechanistically, YY1 directly binds to the UGT2B7 mRNA initiation sequence ATTCAT, thereby transcriptionally regulating the inhibition of UGT2B7 expression. UGT2B7 can regulate the development of breast cancer by regulating estrogen homeostasis in the breast, and the abnormal accumulation of estrogen, especially 4-OHE2, promotes the migration and invasion of breast cancer cells, ultimately causing the development of breast cancer metastasis. In conclusion, YY1 can regulate the UGT2B7-estrogen metabolic axis and induce disturbances in estrogen metabolism in breast tumors, ultimately leading to breast cancer metastasis. Disturbances in estrogen metabolism in the breast tissue may be an important risk factor for breast tumor progression and metastasis SIGNIFICANCE STATEMENT: In this study, we propose for the first time a regulatory relationship between YY1 and the UGT2B7/estrogen metabolism axis and explore the molecular mechanism. Our study shows that the YY1/UGT2B7/estrogen axis plays an important role in the development and metastasis of breast cancer. This study further elucidates the potential mechanisms of YY1-mediated breast cancer metastasis and the possibility and promise of YY1 as a predictor of cancer metastasis.

Biological Basis of Breast Cancer-Related Disparities in Precision Oncology Era

Precision oncology is based on deep knowledge of the molecular profile of tumors, allowing for more accurate and personalized therapy for specific groups of patients who are different in disease susceptibility as well as treatment response. Thus, onco-breastomics is able to discover novel biomarkers that have been found to have racial and ethnic differences, among other types of disparities such as chronological or biological age-, sex/gender- or environmental-related ones. Usually, evidence suggests that breast cancer (BC) disparities are due to ethnicity, aging rate, socioeconomic position, environmental or chemical exposures, psycho-social stressors, comorbidities, Western lifestyle, poverty and rurality, or organizational and health care system factors or access. The aim of this review was to deepen the understanding of BC-related disparities, mainly from a biomedical perspective, which includes genomic-based differences, disparities in breast tumor biology and developmental biology, differences in breast tumors' immune and metabolic landscapes, ecological factors involved in these disparities as well as microbiomics- and metagenomics-based disparities in BC. We can conclude that onco-breastomics, in principle, based on genomics, proteomics, epigenomics, hormonomics, metabolomics and exposomics data, is able to characterize the multiple biological processes and molecular pathways involved in BC disparities, clarifying the differences in incidence, mortality and treatment response for different groups of BC patients.

Association between gut microbiota and menstrual disorders: a two-sample Mendelian randomization study

Background

Evidence from observational studies and clinical trials suggests that the gut microbiota is associated with gynecological diseases. However, the causal relationship between gut microbiota and menstrual disorders remains to be determined.

Methods

We obtained summary data of gut microbiota from the global consortium MiBio-Gen's genome-wide association study (GWAS) dataset and data on menstrual disorders from the IEU Open GWAS project. MR-Egger, weighted median, inverse variance weighted, simple mode, and weighted mode were used to examine the causal association between gut microbiota and menstrual disorders. Thorough sensitivity studies were performed to confirm the data's horizontal pleiotropy, heterogeneity, and robustness.

Results

Through MR analysis of 119 kinds of gut microbiota and 4 kinds of clinical phenotypes, it was discovered that 23 different kinds of gut microbiota were loosely connected to menstrual disorders. After FDR correction, the results showed that only Escherichia/Shigella (p = 0.00032, PFDR = 0.0382, OR = 1.004, 95%CI = 1.002-1.006) is related to menstrual disorders.

Conclusion

According to our MR Analysis, there are indications of a causal relationship between menstrual disorders and gut microbiota. This finding could lead to new discoveries into the mechanisms behind menstrual disorders and clinical research involving the microbiota.

Sex differences in colorectal cancer: with a focus on sex hormone-gut microbiome axis

Sexual dimorphism has been observed in the incidence and prognosis of colorectal cancer (CRC), with men generally exhibiting a slightly higher incidence than women. Research suggests that this difference may be attributed to variations in sex steroid hormone levels and the gut microbiome. The gut microbiome in CRC shows variations in composition and function between the sexes, leading to the concept of 'microgenderome' and 'sex hormone-gut microbiome axis.' Conventional research indicates that estrogens, by promoting a more favorable gut microbiota, may reduce the risk of CRC. Conversely, androgens may have a direct pro-tumorigenic effect by increasing the proportion of opportunistic pathogens. The gut microbiota may also influence sex hormone levels by expressing specific enzymes or directly affecting gonadal function. However, this area remains controversial. This review aims to explore the differences in sex hormone in CRC incidence, the phenomenon of sexual dimorphism within the gut microbiome, and the intricate interplay of the sex hormone-gut microbiome axis in CRC. The objective is to gain a better understanding of these interactions and their potential clinical implications, as well as to introduce innovative approaches to CRC treatment.

The Relationship Between Gut Microbiome Estrobolome and Breast Cancer: A Systematic Review of Current Evidences

Breast cancer is the most frequent kind of cancer and the second leading cause of mortality worldwide, behind heart disease. Next-generation sequencing technologies enables for unprecedented enumeration of human resident gut microorganisms, conferring novel insights into the role of the microbiota in health and individuals with breast cancer. A growing body of research on microbial dysbiosis seems to indicate an elevated risk of health complications including cancer. Although several dysbiosis indices have been proposed, their underlying methodology, as well as the cohorts and conditions of breast cancer patients are significantly different. To date, these indices have not yet been thoroughly reviewed especially when it comes to researching the estrogen-gut microbiota axis. Instead of providing a thorough rating of the most effective diversity measurements, the current work aims to be used to assess the relevance of each study's findings across the demographic data, different subtypes, and stages of breast cancer, and tie them to the estrobolome, which controls the amount of oestrogen that circulates through humans. This review will cover 11 studies which will go into a detailed discussion for the microbiome results of the mentioned studies, leaving to the user the final choice of the most suited indices as well as highlight the observed bacteria found to be related to the estrobolome in hopes of giving the reader a better understanding for the biological cross-talk between gut microbiome and breast cancer progression.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12088-023-01135-z.

Polyphenols Influence the Development of Endometrial Cancer by Modulating the Gut Microbiota

Dysbiosis of the microbiota in the gastrointestinal tract can induce the development of gynaecological tumours, particularly in postmenopausal women, by causing DNA damage and alterations in metabolite metabolism. Dysbiosis also complicates cancer treatment by influencing the body's immune response and disrupting the sensitivity to chemotherapy drugs. Therefore, it is crucial to maintain homeostasis in the gut microbiota through the effective use of food components that affect its structure. Recent studies have shown that polyphenols, which are likely to be the most important secondary metabolites produced by plants, exhibit prebiotic properties. They affect the structure of the gut microbiota and the synthesis of metabolites. In this review, we summarise the current state of knowledge, focusing on the impact of polyphenols on the development of gynaecological tumours, particularly endometrial cancer, and emphasising that polyphenol consumption leads to beneficial modifications in the structure of the gut microbiota.

The causal correlation between gut microbiota abundance and pathogenesis of cervical cancer: a bidirectional mendelian randomization study

Background

Observational studies and animal experiments suggested potential relevance between gut microbiota (GM) and cervical cancer (CC), but the relevance of this association remains to be clarified.

Methods

We performed a two-sample bidirectional Mendelian randomization (MR) analysis to explore whether there was a causal correlation between GM and CC, and the direction of causality.

Results

In primary outcomes, we found that a higher abundance of class Clostridia, family Family XI, genus Alloprevotella, genus Ruminiclostridium 9, and order Clostridiales predicted higher risk of CC, and a higher abundance of class Lentisphaeria, family Acidaminococcaceae, genus Christensenellaceae R7 group, genus Marvinbryantia, order Victivallales, phylum Actinobacteria, and phylum Lentisphaerae predicted lower risk of CC. During verifiable outcomes, we found that a higher abundance of class Methanobacteria, family Actinomycetaceae, family Methanobacteriaceae, genus Lachnospiraceae UCG 010, genus Methanobrevibacter, order Actinomycetales, and order Methanobacteriales predicted a higher risk of CC, and a higher abundance of family Streptococcaceae, genus Dialister, and phylum Bacteroidetes predicted a lower risk of CC, and vice versa.

Conclusion

Our study implied a mutual causality between GM and CC, which provided a novel concept for the occurrence and development of CC, and might promote future functional or clinical analysis.

Insights into the Microbial Composition of Intratumoral, Reproductive Tract, and Gut Microbiota in Ovarian Cancer Patients

According to the latest global cancer data, ovarian cancer is the deadliest among all gynecological malignant tumors and ranks fifth in terms of mortality. Its etiology and pathogenesis are unknown, and the 5-year survival rate of patients with advanced ovarian cancer is only 40% (Sung et al. CA Cancer J Clin 71:209-49, 2021). Recent research has shown that the human microbiota plays a crucial role in the development and progression of tumors, including ovarian cancer. Numerous studies have highlighted the complex connections between the reproductive tract microbiota, intestinal microbiota, and ovarian cancer (Jacobson et al. PeerJ 9:e11574, 2021). Therefore, this chapter will delve into composition, function, and the correlation between microbiota and immunity in the field of ovarian cancer microbiota, as well as the potential of bacteria in therapeutics and diagnostics of ovarian cancer.

Emerging evidence on the role of breast microbiota on the development of breast cancer in high-risk patients

Cancer is a multi-factorial disease, and the etiology of breast cancer (BC) is due to a combination of both genetic and environmental factors. Breast tissue shows a unique microbiota, Proteobacteria and Firmicutes are the most abundant bacteria in breast tissue, and several studies have shown that the microbiota of healthy breast differs from that of BC. Breast microbiota appears to be correlated with different characteristics of the tumor, and prognostic clinicopathologic features. It also appears that there are subtle differences between the microbial profiles of the healthy control and high-risk patients. Genetic predisposition is an extremely important risk factor for BC. BRCA1/2 germline mutations and Li-Fraumeni syndrome are DNA repair deficiency syndromes inherited as autosomal dominant characters that substantially increase the risk of BC. These syndromes exhibit incomplete penetrance of BC expression in carrier subjects. The action of breast microbiota on carcinogenesis might explain why women with a mutation develop cancer and others do not. Among the potential biological pathways through which the breast microbiota may affect tumorigenesis, the most relevant appear to be DNA damage caused by colibactin and other bacterial-derived genotoxins, β-glucuronidase-mediated estrogen deconjugation and reactivation, and HPV-mediated cancer susceptibility. In conclusion, in patients with a genetic predisposition, an unfavorable breast microbiota may be co-responsible for the onset of BC. Prospectively, the ability to modulate the microbiota may have an impact on disease onset and progression in patients at high risk for BC.

The Gut Microbiota: a Novel Player in the Pathogenesis of Uterine Fibroids

Uterine fibroid is a common gynecological disorder that affects women of reproductive age and has emerged as a major public health concern. The symptoms have a negative influence on both their physical health and quality of life. The cost of treatment has a significant impact on the disease's burden. Even though its origin is uncertain, estrogen is thought to be a key player in fibroid pathophysiology. Many theories, including those based on genetic and environmental factors, explain what causes hyper-estrogenic condition in fibroid patients. One such possibility that is currently being explored is the hypothesis that an altered gut microbiome can contribute to the development of diseases characterized by estrogen dominance. Gut dysbiosis is often a "hot area" in the health sciences. According to a recent study, uterine fibroid patients have altered gut microbiome. A variety of risk factors influence both fibroid development and gut homeostasis. Diet, lifestyle, physical activity, and environmental contaminants have an impact on estrogen and the gut flora. A better understanding of uterine fibroids' pathophysiology is required to develop effective preventative and treatment options. A few ways by which the gut microbiota contributes to UF include estrogen, impaired immune function, inflammation, and altered gut metabolites. Therefore, in the future, while treating fibroid patients, various strategies to deal with changes in the gut flora may be advantageous. For developing suggestions for clinical diagnosis and therapy, we reviewed the literature on the relationship between uterine fibroids and the gut microbiota.

The Microbiome in the Obesity-Breast Cancer Axis: Diagnostic and Therapeutic Potential

A growing body of evidence has demonstrated a relationship between the microbiome, adiposity, and cancer development. The microbiome is emerging as an important factor in metabolic disease and cancer pathogenesis. This review aimed to highlight the role of the microbiome in obesity and its association with cancer, with a particular focus on breast cancer. This review discusses how microbiota dysbiosis may contribute to obesity and obesity-related diseases, which are linked to breast cancer. It also explores the potential of the gut microbiome to influence systemic immunity, leading to carcinogenesis via the modulation of immune function. This review underscores the potential use of the microbiome profile as a diagnostic tool and treatment target, with strategies including probiotics, fecal microbiota transplantation, and dietary interventions. However, this emphasizes the need for more research to fully understand the complex relationship between the microbiome, metabolic disorders, and breast cancer. Future studies should focus on elucidating the mechanisms underlying the impact of the microbiome on breast cancer and exploring the potential of the microbiota profile as a biomarker and treatment target.

Association of probiotic ingestion with serum sex steroid hormones among pre- and postmenopausal women from the NHANES, 2013-2016

BACKGROUND

Sex hormone-related diseases, encompassing a wide range of conditions from reproductive disorders to certain cancers, pose significant health challenges worldwide. Recent scientific investigations have highlighted the intricate interplay between the gut microbiome and sex hormone regulation, indicating the potential for microbiota-targeted interventions in the management of such diseases. Although individual studies have elucidated the influence of the gut microbiome on sex hormones, a comprehensive cross-sectional examination of the population-wide prevalence of probiotic intake and its correlation with sex hormones is still lacking.

OBJECTIVES

This study aimed to evaluate the association of probiotic ingestion with sex hormones in pre- and post-menopausal women.

METHODS

We conducted an observational cohort study comprising a nationally representative sample of adults who participated in the National Health and Nutrition Examination Survey between 2013 and 2016. Probiotic ingestion was considered when a subject reported yogurt or probiotic supplement consumption during the 24-h dietary recall or during the Dietary Supplement Use 30-Day questionnaire. A survey-weighted generalized linear model was used to analyze the association between probiotic intake and female/male sex hormones. To reduce selection bias, we used propensity score matching (PSM).

RESULTS

This study included 2,699 women, with 537 of them consuming yogurt and/or dietary supplements containing probiotics, while the remaining 2,162 women did not consume any probiotics. The findings indicated that there were associations between probiotic intake and sex hormone levels in premenopausal and postmenopausal women. For premenopausal women, probiotic intake was positively associated with estradiol (E2) levels. On the contrary, in postmenopausal women, probiotic intake was inversely associated with total testosterone (TT) levels.

CONCLUSIONS

This study indicated that probiotic consumption was associated with higher E2 level in premenopausal women and lower TT level in postmenopausal women. Probiotic intake might be a sensible strategy for preventing sex hormone-related diseases.

Gut Microbiome-Estrobolome Profile in Reproductive-Age Women with Endometriosis

Microbiota is associated with our bodily functions and microenvironment. A healthy, balanced gut microbiome not only helps maintain mucosal integrity, prevents translocation of bacterial content, and contributes to immune status, but also associates with estrogen metabolism. Gut dysbiosis and estrobolome dysfunction have hence been linked to certain estrogen-dependent diseases, including endometriosis. While prior studies on microbiomes and endometriosis have shown conflicting results, most of the observed microbial differences are seen in the genital tract. This case-control study of reproductive-age women utilizes their fecal and urine samples for enzymatic, microbial, and metabolic studies to explore if patients with endometriosis have distinguishable gut microbiota or altered estrogen metabolism. While gut β-glucuronidase activities, microbial diversity, and abundance did not vary significantly between patients with or without endometriosis, fecal samples of patients with endometriosis were more enriched by the Erysipelotrichia class and had higher folds of four estrogen/estrogen metabolites. Further studies are needed to elucidate what these results imply and whether there indeed is an association or causation between gut microbiota and endometriosis.

Exploring the human microbiome - A step forward for precision medicine in breast cancer

BACKGROUND

The second most frequent cancer in the world and the most common malignancy in women is breast cancer. Breast cancer is a significant health concern in India with a high mortality-to-incidence ratio and presentation at a younger age.

RECENT FINDINGS

Recent studies have identified gut microbiota as a significant factor that can have an influence on the development, treatment, and prognosis of breast cancer. This review article aims to describe the influence of microbial dysbiosis on breast cancer occurrence and the possible interactions between oncobiome and specific breast cancer molecular subtypes. The review further also discusses the role of epigenetics and diet/nutrition in the regulation of the gut and breast microbiome and its association with breast cancer prevention, therapy, and recurrence. Additionally, the recent technological advances in microbiome research, including next-generation sequencing (NGS) technologies, genome sequencing, single-cell sequencing, and microbial metabolomics along with recent advances in artificial intelligence (AI) have also been reviewed. This is an attempt to present a comprehensive status of the microbiome as a key cancer biomarker.

CONCLUSION

We believe that correlating microbiome and carcinogenesis is important as it can provide insights into the mechanisms by which microbial dysbiosis can influence cancer development and progression, leading to the potential use of the microbiome as a tool for prognostication and personalized therapy.

Drug and gut microbe relationships: Moving beyond antibiotics

Our understanding of drug-microbe relationships has evolved from viewing microbes as mere drug producers to a dynamic, modifiable system where they can serve as drugs or targets of precision pharmacology. This review highlights recent findings on the gut microbiome, particularly focusing on four aspects of research: (i) drugs for bugs, covering recent strategies for targeting gut pathogens; (ii) bugs as drugs, including probiotics; (iii) drugs from bugs, including postbiotics; and (iv) bugs and drugs, discussing additional types of drug-microbe interactions. This review provides a perspective on future translational research, including efficient companion diagnostics in pharmaceutical interventions.

Oestrogen receptor-independent actions of oestrogen in cancer

Oestrogen, the primary female sex hormone, plays a significant role in tumourigenesis. The major pathway for oestrogen is via binding to its receptor [oestrogen receptor (ERα or β)], followed by nuclear translocation and transcriptional regulation of target genes. Almost 70% of breast tumours are ER + , and endocrine therapies with selective ER modulators (tamoxifen) have been successfully applied. As many as 25% of tamoxifen-treated patients experience disease relapse within 5 years upon completion of chemotherapy. In such cases, the ER-independent oestrogen actions provide a plausible explanation for the resistance, as well as expands the existing horizon of available drug targets. ER-independent oestrogen signalling occurs via one of the following pathways: signalling through membrane receptors, oxidative catabolism giving rise to genotoxic metabolites, effects on mitochondria and redox balance, and induction of inflammatory cytokines. The current review focuses on the non-classical oestrogen signalling, its role in cancer, and its clinical significance.

Microbial endocrinology: the mechanisms by which the microbiota influences host sex steroids

Recent progress in microbial endocrinology has propelled this field from initially providing correlational links to defining the mechanisms by which microbes influence systemic sex hormones. Importantly, the interaction between the gut-resident bacteria and host-secreted hormones has been shown to be critical for host development as well as hormone-mediated disease progression. This review investigates how microbes affect active sex hormone levels, with a focus on gut-associated bacteria hormonal modifications and the resulting host physiological status. Specifically, we focus on the ability of the microbiota to reactivate estrogens and deactivate androgens and thereby influence systemic levels of host hormones in a clinically significant manner.

Current and future research on the association between gut microbiota and breast cancer

Breast cancer (BC) is a prevalent malignancy. There exists a strong association between gut microbiota (GM) and the development of BC. The GM composition in individuals with BC significantly differs from that in their healthy counterparts. Furthermore, the distribution of GM varies significantly among individuals with different types of BC. The GM can impact BC through metabolite secretion, the gut-mammary axis, and other pathways. Modulating the GM can serve as a very promising potential therapeutic strategy in the treatment of BC. This article will summarize existing research, focusing on the relationship between intestinal microbiota and BC. At the same time, the project will also analyze the application value of intestinal microorganisms in BC intervention work, so as to provide a reference for the further development of BC prevention and treatment work.

Intra-tumoral microbial community profiling and associated metabolites alterations of TNBC

Triple-negative breast cancer (TNBC) presents significant challenges to female health owing to the lack of therapeutic targets and its poor prognosis. In recent years, in the field of molecular pathology, there has been a growing focus on the role of intra-tumoral microbial communities and metabolic alterations in tumor cells. However, the precise mechanism through which microbiota and their metabolites influence TNBC remains unclear and warrants further investigation. In this study, we analyzed the microbial community composition in various subtypes of breast cancer through 16S rRNA MiSeq sequencing of formalin-fixed, paraffin-embedded (FFPE) tissue samples. Notably, Turicibacter, a microbe associated with cancer response, exhibited a significantly higher abundance in TNBC. Similarly, mass spectrometry-based metabolomic analysis revealed substantial differences in specific metabolites, such as nutriacholic, pregnanetriol, and cortol. Furthermore, we observed significant correlations between the intra-tumoral microbiome, clinicopathological characteristics, and human epidermal growth factor receptor-2 expression(HER2). Three microbial taxa (Cytophagaceae, Conexibacteraceae, and Flavobacteriaceae) were associated with tumor-infiltrating lymphocytes(TILs), which are indicative of antitumor immunity. This study creatively utilized FFPE tissue samples to assess intra-tumoral microbial communities and their related metabolic correlations, presenting avenues for the identification of novel diagnostic biomarkers, the development of therapeutic strategies, and the early clinical diagnosis of TNBC.

The tremendous clinical potential of the microbiota in the treatment of breast cancer: the next frontier

Although significant advances have been made in the diagnosis and treatment of breast cancer (BC) in recent years, BC remains the most common cancer in women and one of the main causes of death among women worldwide. Currently, more than half of BC patients have no known risk factors, emphasizing the significance of identifying more tumor-related factors. Therefore, we urgently need to find new therapeutic strategies to improve prognosis. Increasing evidence demonstrates that the microbiota is present in a wider range of cancers beyond colorectal cancer. BC and breast tissues also have different types of microbiotas that play a key role in carcinogenesis and in modulating the efficacy of anticancer treatment, for instance, chemotherapy, radiotherapy, and immunotherapy. In recent years, studies have confirmed that the microbiota can be an important factor directly and/or indirectly affecting the occurrence, metastasis and treatment of BC by regulating different biological processes, such as estrogen metabolism, DNA damage, and bacterial metabolite production. Here, we review the different microbiota-focused studies associated with BC and explore the mechanisms of action of the microbiota in BC initiation and metastasis and its application in various therapeutic strategies. We found that the microbiota has vital clinical value in the diagnosis and treatment of BC and could be used as a biomarker for prognosis prediction. Therefore, modulation of the gut microbiota and its metabolites might be a potential target for prevention or therapy in BC.

Emerging Relationship between the Gut Microbiome and Prostate Cancer

The human gut microbiota changes under the influence of environmental and genetic factors, affecting human health. Extensive studies have revealed that the gut microbiome is closely associated with many non-intestinal diseases. Among these, the influence of the gut microbiome on cancer biology and the efficacy of cancer therapy has attracted much attention. Prostate cancer cells are affected by direct contact with the microbiota of local tissues and urine, and a relationship between prostate cancer cells and the gut microbiota has been suggested. In the human gut microbiota, bacterial composition differs depending on prostate cancer characteristics, such as histological grade and castration resistance. Moreover, the involvement of several intestinal bacteria in testosterone metabolism has been demonstrated, suggesting that they may affect prostate cancer progression and treatment through this mechanism. Basic research indicates that the gut microbiome also plays an important role in the underlying biology of prostate cancer through multiple mechanisms owing to the activity of microbial-derived metabolites and components. In this review, we describe the evidence surrounding the emerging relationship between the gut microbiome and prostate cancer, termed the "gut-prostate axis."

Gut microbiome causal impacts on the prognosis of breast cancer: a Mendelian randomization study

BACKGROUND

Growing evidence has shown that gut microbiome composition is associated with breast cancer (BC), but the causality remains unknown. We aimed to investigate the link between BC prognosis and the gut microbiome at various oestrogen receptor (ER) statuses.

METHODS

We performed a genome-wide association study (GWAS) to analyse the gut microbiome of BC patients, the dataset for which was collected by the Breast Cancer Association Consortium (BCAC). The analysis was executed mainly via inverse variance weighting (IVW); the Mendelian randomization (MR) results were verified by heterogeneity tests, sensitivity analysis, and pleiotropy analysis.

RESULTS

Our findings identified nine causal relationships between the gut microbiome and total BC cases, with ten and nine causal relationships between the gut microbiome and ER-negative (ER-) and ER-positive (ER+) BC, respectively. The family Ruminococcaceae and genus Parabacteroides were most apparent among the three categories. Moreover, the genus Desulfovibrio was expressed in ER- BC and total BC, whereas the genera Sellimonas, Adlercreutzia and Rikenellaceae appeared in the relationship between ER + BC and total BC.

CONCLUSION

Our MR inquiry confirmed that the gut microbiota is causally related to BC. This further explains the link between specific bacteria for prognosis of BC at different ER statuses. Considering that potential weak instrument bias impacts the findings and that the results are limited to European females due to data constraints, further validation is crucial.

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.

A critical review of microplastics toxicity and potential adverse outcome pathway in human gastrointestinal tract following oral exposure

Microplastics (MPs) are typically produced via environmental degradation of larger plastics, where they enter the human food chain. MPs are complex materials containing chemical and physical characteristics that can potentially affect their hazard and exposure. These physical properties can be altered by environmental exposure potentially altering any risk assessment conducted on the primary material. We conducted a literature review using an Adverse Outcome Pathway (AOP)-based approach from Molecular Initiating Event (MIE) to cell effect event to identify multiple knowledge gaps that affect MPs hazard assessment. There is some convergence of key biological events but could relate to most lying along well-established biological effector pathways such as apoptosis which can respond to many MIEs. In contrast, MIEs of chemicals will be via protein interaction. As MPs may occur in the lumen of the alimentary canal for example to the mucus, therefore, not requiring translocation of MPs across the epithelial membrane. At the other end of the AOP, currently it is not possible to identify a single adverse outcome at the organ level. This work did establish a clear need to understand both external and internal exposure (resulting from translocation) and develop hazard data at both levels to inform on risk assessments.

A Holistic Approach to Hard-to-Treat Cancers: The Future of Immunotherapy for Glioblastoma, Triple Negative Breast Cancer, and Advanced Prostate Cancer

Immunotherapy represents an attractive avenue for cancer therapy due to its tumour specificity and relatively low frequency of adverse effects compared to other treatment modalities. Despite many advances being made in the field of cancer immunotherapy, very few immunotherapeutic treatments have been approved for difficult-to-treat solid tumours such as triple negative breast cancer (TNBC), glioblastoma multiforme (GBM), and advanced prostate cancer (PCa). The anatomical location of some of these cancers may also make them more difficult to treat. Many trials focus solely on immunotherapy and have failed to consider or manipulate, prior to the immunotherapeutic intervention, important factors such as the microbiota, which itself is directly linked to lifestyle factors, diet, stress, social support, exercise, sleep, and oral hygiene. This review summarises the most recent treatments for hard-to-treat cancers whilst factoring in the less conventional interventions which could tilt the balance of treatment in favour of success for these malignancies.

Implications of receptor for advanced glycation end products for progression from obesity to diabetes and from diabetes to cancer

Obesity and type 2 diabetes mellitus (T2DM) are chronic pathologies with a high incidence worldwide. They share some pathological mechanisms, including hyperinsulinemia, the production and release of hormones, and hyperglycemia. The above, over time, affects other systems of the human body by causing tissue hypoxia, low-grade inflammation, and oxidative stress, which lay the pathophysiological groundwork for cancer. The leading causes of death globally are T2DM and cancer. Other main alterations of this pathological triad include the accumulation of advanced glycation end products and the release of endogenous alarmins due to cell death (i.e., damage-associated molecular patterns) such as the intracellular proteins high-mobility group box protein 1 and protein S100 that bind to the receptor for advanced glycation products (RAGE) - a multiligand receptor involved in inflammatory and metabolic and neoplastic processes. This review analyzes the latest advanced reports on the role of RAGE in the development of obesity, T2DM, and cancer, with an aim to understand the intracellular signaling mechanisms linked with cancer initiation. This review also explores inflammation, oxidative stress, hypoxia, cellular senescence, RAGE ligands, tumor microenvironment changes, and the “cancer hallmarks” of the leading tumors associated with T2DM. The assimilation of this information could aid in the development of diagnostic and therapeutic approaches to lower the morbidity and mortality associated with these diseases.

Gut colonization with an obesity-associated enteropathogenic microbe modulates the premetastatic niches to promote breast cancer lung and liver metastasis

Introduction

Obesity, an independent risk factor for breast cancer growth and metastatic progression, is also closely intertwined with gut dysbiosis; and both obese state and dysbiosis promote each other. Enteric abundance of Bacteroides fragilis is strongly linked with obesity, and we recently discovered the presence of B. fragilis in malignant breast cancer. Given that enterotoxigenic B. fragilis or ETBF, which secretes B. fragilis toxin (BFT), has been identified as a procarcinogenic microbe in breast cancer, it is necessary to examine its impact on distant metastasis and underlying systemic and localized alterations promoting metastatic progression of breast cancer.

Methods

We used syngeneic mammary intraductal (MIND) model harboring gut colonization with ETBF to query distant metastasis of breast cancer cells. Alterations in the immune network and cytokines/chemokines in the tumor microenvironment and distant metastatic sites were examined using flow cytometry, immunohistochemistry, and multiplex arrays.

Results

ETBF infection initiates a systemic inflammation aiding in the establishment of the premetastatic niche formation in vital organs via increased proinflammatory and protumorigenic cytokines like IL17A, IL17E, IL27p28, IL17A/F, IL6, and IL10 in addition to creating a prometastatic immunosuppressive environment in the liver and lungs rich in myeloid cells, macrophages, and T regulatory cells. It induces remodeling of the tumor microenvironment via immune cell and stroma infiltration, increased vasculogenesis, and an EMT-like response, thereby encouraging early metastatic dissemination ready to colonize the conducive environment in liver and lungs of the breast tumor-bearing mice.

Discussion

In this study, we show that enteric ETBF infection concomitantly induces systemic inflammation, reshapes the tumor immune microenvironment, and creates conducive metastatic niches to potentiate early dissemination and seeding of metastases to liver and lung tissues in agreement with the "seed and soil hypothesis." Our results also support the ETBF-induced "parallel model" of metastasis that advocates for an early dissemination of tumor cells that form metastatic lesions independent of the primary tumor load.