The Microbiome as a Component of the Tumor Microenvironment

Guideline for designing microbiome studies in neoplastic diseases

Oncobiosis has emerged as a key contributor to the development, and modulator of the treatment efficacy of cancer. Hereby, we review the modalities through which the oncobiome can support the progression of tumors, and the emerging therapeutic opportunities they present. The review highlights the inherent challenges and limitations faced in sampling and accurately characterizing oncobiome. Additionally, the review underscores the critical need for the standardization of microbial analysis techniques and the consistent reporting of microbiome data. We provide a suggested metadata set that should accompany microbiome datasets from oncological settings so that studies remain comparable and decipherable.

Modulation of Gut Microbial Biomarkers and Metabolites in Cancer Management by Tea Compounds

Cancers are causing millions of deaths and leaving a huge clinical and economic burden. High costs of cancer drugs are limiting their access to the growing number of cancer cases. The development of more affordable alternative therapy could reach more patients. As gut microbiota plays a significant role in the development and treatment of cancer, microbiome-targeted therapy has gained more attention in recent years. Dietary and natural compounds can modulate gut microbiota composition while providing broader and more accessible access to medicine. Tea compounds have been shown to have anti-cancer properties as well as modulate the gut microbiota and their related metabolites. However, there is no comprehensive review that focuses on the gut modulatory effects of tea compounds and their impact on reshaping the metabolic profiles, particularly in cancer models. In this review, the effects of different tea compounds on gut microbiota in cancer settings are discussed. Furthermore, the relationship between these modulated bacteria and their related metabolites, along with the mechanisms of how these changes led to cancer intervention are summarized.

Interaction between intestinal flora and gastric cancer in tumor microenvironment

Gastric Cancer (GC) is a prevalent malignancy globally and is the third leading cause of cancer-related deaths. Recent researches focused on the correlation between intestinal flora and GC. Studies indicate that bacteria can influence the development of gastrointestinal tumors by releasing bacterial extracellular vesicles (BEVs). The Tumor microenvironment (TME) plays an important role in tumor survival, with the interaction between intestinal flora, BEVs, and TME directly impacting tumor progression. Moreover, recent studies have demonstrated that intestinal microflora and BEVs can modify TME to enhance the effectiveness of antitumor drugs. This review article provides an overview and comparison of the biological targets through which the intestinal microbiome regulates TME, laying the groundwork for potential applications in tumor diagnosis, treatment, and prognosis.

The role of the gut microbiome in gastrointestinal cancers

The gut microbiota present in the human digestive system is incredibly varied and is home to trillions of microorganisms. The gut microbiome is shaped at birth, while numerous genetic, dietary, and environmental variables primarily influence the microbiome composition. The importance of gut microbiota on host health is becoming more widely acknowledged. Digestion, intestinal permeability, and immunological and metabolism responses can all be affected by changes in the composition and function of the gut microbiota. There is mounting evidence that the microbial population's complex traits are important biomarkers and indicators of patient outcomes in cancer and its therapies. Numerous studies have demonstrated that changed commensal gut microorganisms contribute to the development and spread of cancer through various routes. Despite the ongoing controversy surrounding the gut microbiome and gastrointestinal cancer, accumulating evidence points to a potentially far more intricate connection than a simple cause-and-effect relationship. SIMPLE SUMMARY: Due to their high frequency and fatality rate, gastrointestinal cancers are regarded as a severe public health issue with complex medical and economic burdens. The gut microbiota may directly or indirectly interact with existing therapies like immunotherapy and chemotherapy, affecting how well a treatment works. The gut microbiome influences the immune response's activity, function, and development. Generally, certain gut bacteria impact the antitumor actions during cancer by creating particular metabolites or triggering T-cell responses. Yet, certain bacterial species have been found to promote cellular proliferation and metastasis in cancer, and comprehending these interactions in the context of cancer may help identify possible treatment targets. Notwithstanding the improvements in the field, additional research is still required to comprehend the underlying processes, examine the effects on existing therapies, and pinpoint certain bacteria and immune cells that can cause this interaction.

Role of circular RNAs and gut microbiome in gastrointestinal cancers and therapeutic targets

Gastrointestinal cancers are a huge worldwide health concern, which includes a wide variety of digestive tract cancers. Circular RNAs (circRNAs), a kind of non-coding RNA (ncRNAs), are a family of single-stranded, covalently closed RNAs that have become recognized as crucial gene expression regulators, having an impact on several cellular functions in cancer biology. The gut microbiome, which consists of several different bacteria, actively contributes to the regulation of host immunity, inflammation, and metabolism. CircRNAs and the gut microbiome interact significantly to greatly affect the growth of GI cancer. Several studies focus on the complex functions of circRNAs and the gut microbiota in GI cancers, including esophageal cancer, colorectal cancer, gastric cancer, hepatocellular cancer, and pancreatic cancer. It also emphasizes how changed circRNA expression profiles and gut microbiota affect pathways connected to malignancy as well as how circRNAs affect hallmarks of gastrointestinal cancers. Furthermore, circRNAs and gut microbiota have been recommended as biological markers for therapeutic targets as well as diagnostic and prognostic purposes. Targeting circRNAs and the gut microbiota for the treatment of gastrointestinal cancers is also being continued to study. Despite significant initiatives, the connection between circRNAs and the gut microbiota and the emergence of gastrointestinal cancers remains poorly understood. In this study, we will go over the most recent studies to emphasize the key roles of circRNAs and gut microbiota in gastrointestinal cancer progression and therapeutic options. In order to create effective therapies and plan for the future gastrointestinal therapy, it is important to comprehend the functions and mechanisms of circRNAs and the gut microbiota.

Host-microbiota interactions contributing to the heterogeneous tumor microenvironment in colorectal cancer

Colorectal cancer (CRC) exhibits pronounced heterogeneity and is categorized into four widely accepted consensus molecular subtypes (CMSs) with unique tumor microenvironments (TMEs). However, the intricate landscape of the microbiota and host-microbiota interactions within these TMEs remains elusive. Using RNA-sequencing data from The Cancer Genome Atlas, we analyzed the host transcriptomes and intratumoral microbiome profiles of CRC samples. Distinct host genes and microbial genera were identified among the CMSs. Immune microenvironments were evaluated using CIBERSORTx and ESTIMATE, and microbial coabundance patterns were assessed with FastSpar. Through LASSO penalized regression, we explored host-microbiota associations for each CMS. Our analysis revealed distinct host gene signatures within the CMSs, which encompassed ferroptosis-related genes and specific immune microenvironments. Moreover, we identified 293, 153, 66, and 109 intratumoral microbial genera with differential abundance, and host-microbiota associations contributed to distinct TMEs, characterized by 829, 1,270, 634, and 1,882 robust gene-microbe associations for each CMS in CMS1-CMS4, respectively. CMS1 featured inflammation-related HSF1 activation and gene interactions within the endothelin pathway and Flammeovirga. Integrin-related genes displayed positive correlations with Sutterella in CMS2, whereas CMS3 spotlighted microbial associations with biosynthetic and metabolic pathways. In CMS4, genes involved in collagen biosynthesis showed positive associations with Sutterella, contributing to disruptions in homeostasis. Notably, immune-rich subtypes exhibited pronounced ferroptosis dysregulation, potentially linked to tissue microbial colonization. This comprehensive investigation delineates the diverse landscapes of the TME within each CMS, incorporating host genes, intratumoral microbiota, and their complex interactions. These findings shed light on previously uncharted mechanisms underpinning CRC heterogeneity and suggest potential therapeutic targets.NEW & NOTEWORTHY This study determined the following: 1) providing a comprehensive landscape of consensus molecular subtype (CMS)-specific tumor microenvironments (TMEs); 2) constructing CMS-specific networks, including host genes, intratumoral microbiota, and enriched pathways, analyzing their associations to uncover unique patterns that demonstrate the intricate interplay within the TME; and 3) revealing a connection between immune-rich subtypes and ferroptosis activation, suggesting a potential regulatory role of the microbiota in ferroptosis dysregulation of the colorectal cancer TME.

Gut microbiota and its therapeutic implications in tumor microenvironment interactions

The development of cancer is not just the growth and proliferation of a single transformed cell, but its tumor microenvironment (TME) also coevolves with it, which is primarily involved in tumor initiation, development, metastasis, and therapeutic responses. Recent years, TME has been emerged as a potential target for cancer diagnosis and treatment. However, the clinical efficacy of treatments targeting the TME, especially its specific components, remains insufficient. In parallel, the gut microbiome is an essential TME component that is crucial in cancer immunotherapy. Thus, assessing and constructing frameworks between the gut microbiota and the TME can significantly enhance the exploration of effective treatment strategies for various tumors. In this review the role of the gut microbiota in human cancers, including its function and relationship with various tumors was summarized. In addition, the interaction between the gut microbiota and the TME as well as its potential applications in cancer therapeutics was described. Furthermore, it was summarized that fecal microbiota transplantation, dietary adjustments, and synthetic biology to introduce gut microbiota-based medical technologies for cancer treatment. This review provides a comprehensive summary for uncovering the mechanism underlying the effects of the gut microbiota on the TME and lays a foundation for the development of personalized medicine in further studies.

Dual-Labeled Single Fluorescent Probes for the Simultaneous Two-Color Visualization of Dual Organelles and for Monitoring Cell Autophagy

Dual-labeled single fluorescent probes are powerful tools for studying autophagy on the molecular scale, yet their development has been hampered by design complexity and a lack of valid strategies. Herein, for the first time, we introduce a combinatorial regulation strategy to fabricate dual-labeled probes for studying autophagy by integrating the specific organelle-targeting group and the functional fluorescence switch into a pentacyclic pyrylium scaffold (latent dual-target scaffold). For proof of concept, we prepared a range of dual-labeled probes (TMOs) that display different emission colors in duple organelles. In these probes, TMO1 and TMO2 enabled the simultaneous two-color visualization of the lysosomes and mitochondria. The other probes (TMO3 and TMO4) discriminatively targeted lysosomes/nucleolus and lysosomes/lipid droplets (LDs) with dual-color emission characteristics, respectively. Intriguingly, by simply connecting the endoplasmic reticulum (ER) targeting group to the pentacyclic pyrylium scaffold, we created the first dual-labeled probe TMO5 for simultaneously labeling lysosomes/ER in distinctive fluorescent colors. Subsequently, using the dual-labeled probe TMO2, drug-induced mitophagy was successfully recorded by evaluating the alterations of multiple mitophagy-related parameters, and the mitophagy defects in a cellular model of Parkinson's disease (PD) were also revealed by simultaneous dual-color/dual-organelle imaging. Further, the probe TMO4 can track the movement of lysosomes and LDs in real time and monitor the dynamic process of lipophagy. Therefore, this work not only presents attractive dual-labeled probes to promote the study of organelle interactions during autophagy but also provides a promising combinatorial regulation strategy that may be generalized for designing other dual-labeled probes with multiple organelle combinations.

Microbial metabolites are involved in tumorigenesis and development by regulating immune responses

The human microbiota is symbiotic with the host and can create a variety of metabolites. Under normal conditions, microbial metabolites can regulate host immune function and eliminate abnormal cells in a timely manner. However, when metabolite production is abnormal, the host immune system might be unable to identify and get rid of tumor cells at the early stage of carcinogenesis, which results in tumor development. The mechanisms by which intestinal microbial metabolites, including short-chain fatty acids (SCFAs), microbial tryptophan catabolites (MTCs), polyamines (PAs), hydrogen sulfide, and secondary bile acids, are involved in tumorigenesis and development by regulating immune responses are summarized in this review. SCFAs and MTCs can prevent cancer by altering the expression of enzymes and epigenetic modifications in both immune cells and intestinal epithelial cells. MTCs can also stimulate immune cell receptors to inhibit the growth and metastasis of the host cancer. SCFAs, MTCs, bacterial hydrogen sulfide and secondary bile acids can control mucosal immunity to influence the occurrence and growth of tumors. Additionally, SCFAs, MTCs, PAs and bacterial hydrogen sulfide can also affect the anti-tumor immune response in tumor therapy by regulating the function of immune cells. Microbial metabolites have a good application prospect in the clinical diagnosis and treatment of tumors, and our review provides a good basis for related research.

Manipulating the gut and tumor microbiota for immune checkpoint inhibitor therapy: from dream to reality

The past decade has witnessed a revolution in cancer treatment by shifting from conventional therapies to immune checkpoint inhibitors (ICIs). These immunotherapies unleash the host immune system against the tumor and have achieved unprecedented durable remission. However, 80% of patients do not respond. This review discusses how bacteria are unexpected drivers that reprogram tumor immunity. Manipulating the microbiota impacts on tumor development and reprograms the tumor microenvironment (TME) of mice on immunotherapy. We anticipate that harnessing commensals and the tumor microbiome holds promise to identify patients who will benefit from immunotherapy and guide the choice of new ICI combinations to advance treatment efficacy.

Bioactive Compounds of Dietary Origin and Their Influence on Colorectal Cancer as Chemoprevention

Colorectal cancer (CRC) is one of the most common causes of death and the third most diagnosed cancer worldwide. The tumor microenvironment and cancer stem cells participate in colorectal tumor progression and can dictate malignancy. Nutrition status affects treatment response and the progression or recurrence of the tumor. This review summarizes the main bioactive compounds against the molecular pathways related to colorectal carcinogenesis. Moreover, we focus on the compounds with chemopreventive properties, mainly polyphenols and carotenoids, which are highly studied dietary bioactive compounds present in major types of food, like vegetables, fruits, and seeds. Their proprieties are antioxidant and gut microbiota modulation, important in the intestine because they decrease reactive oxygen species and inflammation, both principal causes of cancer. These compounds can promote apoptosis and inhibit cell growth, proliferation, and migration. Combined with oncologic treatment, a sensitization to first-line colorectal chemotherapy schemes, such as FOLFOX and FOLFIRI, is observed, making them an attractive and natural support in the oncologic treatment of CRC.

Role of the Microbiota in Skin Neoplasms: New Therapeutic Horizons

The skin and the gut are regularly colonized by a variety of microorganisms capable of interacting with the immune system through their metabolites and influencing the balance between immune tolerance and inflammation. Alterations in the composition and diversity of the skin microbiota have been described in various cutaneous diseases, including skin cancer, and the actual function of the human microbiota in skin carcinogenesis, such as in progression and metastasis, is currently an active area of research. The role of Human Papilloma Virus (HPV) in the pathogenesis of squamous cell carcinoma is well consolidated, especially in chronically immunosuppressed patients. Furthermore, an imbalance between Staphylococcus spp., such as Staphylococcus epidermidis and aureus, has been found to be strongly related to the progression from actinic keratosis to squamous cell carcinoma and differently associated with various stages of the diseases in cutaneous T-cell lymphoma patients. Also, in melanoma patients, differences in microbiota have been related to dissimilar disease course and prognosis and may affect the effectiveness and tolerability of immune checkpoint inhibitors, which currently represent one of the best chances of a cure. From this point of view, acting on microbiota can be considered a possible therapeutic option for patients with advanced skin cancers, even if several issues are still open.

The third dimension of tumor microenvironment-The importance of tumor stroma in 3D cancer models

Recent advances in the three-dimensional (3D) cancer models give rise to a plethora of new possibilities in the development of anti-cancer drug therapies and bring us closer to personalized medicine. Three-dimensional models are undoubtedly more authentic than traditional two-dimensional (2D) cell cultures. Nowadays, they are becoming preferentially used in most cancer research fields due to their more accurate biomimetic characteristics. On the contrary, they still lack the cellular and matrix complexity of the native tumor microenvironment (TME). This review focuses on the description of existing 3D models, the incorporation of TME and fluidics into these models, and their perspective in the future research. It is clear that such an improvement would need not only biological but also technical progress. Therefore, the modern approach to anti-cancer drug discovery should involve various fields.

Lifestyles, arterial aging, and its relationship with the intestinal and oral microbiota (MIVAS III study): a research protocol for a cross-sectional multicenter study

Background

The microbiota is increasingly recognized as a significant factor in the pathophysiology of many diseases, including cardiometabolic diseases, with lifestyles probably exerting the greatest influence on the composition of the human microbiome. The main objectives of the study are to analyze the association of lifestyles (diet, physical activity, tobacco, and alcohol) with the gut and oral microbiota, arterial aging, and cognitive function in subjects without cardiovascular disease in the Iberian Peninsula. In addition, the study will examine the mediating role of the microbiome in mediating the association between lifestyles and arterial aging as well as cognitive function.

Methods and analysis

MIVAS III is a multicenter cross-sectional study that will take place in the Iberian Peninsula. One thousand subjects aged between 45 and 74 years without cardiovascular disease will be selected. The main variables are demographic information, anthropometric measurements, and habits (tobacco and alcohol). Dietary patterns will be assessed using a frequency consumption questionnaire (FFQ) and the Mediterranean diet adherence questionnaire. Physical activity levels will be evaluated using the International Physical Activity Questionnaire (IPAQ), Marshall Questionnaire, and an Accelerometer (Actigraph). Body composition will be measured using the Inbody 230 impedance meter. Arterial aging will be assessed through various means, including measuring medium intimate carotid thickness using the Sonosite Micromax, conducting analysis with pulse wave velocity (PWA), and measuring pulse wave velocity (cf-PWV) using the Sphygmocor System. Additional cardiovascular indicators such as Cardio Ankle Vascular Index (CAVI), ba-PWV, and ankle-brachial index (Vasera VS-2000^®) will also be examined. The study will analyze the intestinal microbiota using the OMNIgene GUT kit (OMR-200) and profile the microbiome through massive sequencing of the 16S rRNA gene. Linear discriminant analysis (LDA), effect size (LEfSe), and compositional analysis, such as ANCOM-BC, will be used to identify differentially abundant taxa between groups. After rarefying the samples, further analyses will be conducted using MicrobiomeAnalyst and R v.4.2.1 software. These analyses will include various aspects, such as assessing α and β diversity, conducting abundance profiling, and performing clustering analysis.

Discussion

Lifestyle acts as a modifier of microbiota composition. However, there are no conclusive results demonstrating the mediating effect of the microbiota in the relationship between lifestyles and cardiovascular diseases. Understanding this relationship may facilitate the implementation of strategies for improving population health by modifying the gut and oral microbiota.

Trial registration

clinicaltrials.gov/ct2/show/NCT04924907, ClinicalTrials.gov, identifier: NCT04924907. Registered on 21 April 2021.

Mycoplasma infection of cancer cells enhances anti-tumor effect of oxidized methylcytidines

Oxidized methylcytidines 5-hydroxymethyl-2'deoxycytidine (5hmdC) and 5-formy-2'deoxycytidine (5fdC) are deaminated by cytidine deaminase (CDA) into genome-toxic variants of uridine, triggering DNA damage and cell death. These compounds are promising chemotherapeutic agents for cancer cells that are resistant to pyrimidine derivative drugs, such as decitabine and cytarabine, which are inactivated by CDA. In our study, we found that cancer cells infected with mycoplasma exhibited a markedly increased sensitivity to 5hmdC and 5fdC, which was independent of CDA expression of cancer cells. In vitro biochemical assay showed that the homologous CDA protein from mycoplasma was capable of deaminating 5hmdC and 5fdC into their uridine form. Moreover, mycoplasma infection increased the sensitivity of cancer cells to 5hmdC and 5fdC, whereas administration of Tetrahydrouridine (THU) attenuated this effect, suggesting that mycoplasma CDA confers a similar effect as human CDA. As mycoplasma infection occurs in many primary tumors, our findings suggest that intratumoral microbes could enhance the tumor-killing effect and expand the utility of oxidized methylcytidines in cancer treatment.

Awareness of intratumoral bacteria and their potential application in cancer treatment

Hitherto, the recognition of the microbiota role in tumorigenesis and clinical studies mostly focused on the intestinal flora. In contrast to the gut microbiome, microorganisms resident in tumor tissue are in close contact with cancer cells and therefore have the potential to have similar or even different functional patterns to the gut flora. Some investigations have shown intratumoral bacteria, which might come from commensal microbiota in mucosal areas including the gastrointestinal tract and oral cavity, or from nearby normal tissues. The existence, origin, and interactions of intratumoral bacteria with the tumor microenvironment all contribute to intratumoral microorganism heterogeneity. Intratumoral bacteria have a significant role in tumor formation. They can contribute to cancer at the genetic level by secreting poisons that directly damage DNA and also intimately related to immune system response at the systemic level. Intratumoral bacteria have an impact on chemotherapy and immunotherapy in cancer. Importantly, various properties of bacteria such as targeting and ease of modification make them powerful candidates for precision therapy, and combining microbial therapies with other therapies is expected to improve the effectiveness of cancer treatment. In this review, we mainly described the heterogeneity and potential sources of intratumoral bacteria, overviewed the important mechanisms by which they were involved in tumor progression, and summarized their potential value in oncology therapy. At last, we highlight the problems of research in this field, and look forward to a new wave of studies using the various applications of intratumoral microorganisms in cancer therapy.

Endocrine Disruptors in Food, Estrobolome and Breast Cancer

The microbiota is now recognized as one of the major players in human health and diseases, including cancer. Regarding breast cancer (BC), a clear link between microbiota and oncogenesis still needs to be confirmed. Yet, part of the bacterial gene mass inside the gut, constituting the so called "estrobolome", influences sexual hormonal balance and, since the increased exposure to estrogens is associated with an increased risk, may impact on the onset, progression, and treatment of hormonal dependent cancers (which account for more than 70% of all BCs). The hormonal dependent BCs are also affected by environmental and dietary endocrine disruptors and phytoestrogens which interact with microbiota in a bidirectional way: on the one side disruptors can alter the composition and functions of the estrobolome, ad on the other the gut microbiota influences the metabolism of endocrine active food components. This review highlights the current evidence about the complex interplay between endocrine disruptors, phytoestrogens, microbiome, and BC, within the frames of a new "oncobiotic" perspective.

FADS1-arachidonic acid axis enhances arachidonic acid metabolism by altering intestinal microecology in colorectal cancer

Colonocyte metabolism shapes the microbiome. Metabolites are the main mediators of information exchange between intestine and microbial communities. Arachidonic acid (AA) is an essential polyunsaturated fatty acid and its role in colorectal cancer (CRC) remains unexplored. In this study, we show that AA feeding promotes tumor growth in AOM/DSS and intestinal specific Apc^-/- mice via modulating the intestinal microecology of increased gram-negative bacteria. Delta-5 desaturase (FADS1), a rate-limiting enzyme, is upregulated in CRC and effectively mediates AA synthesis. Functionally, FADS1 regulates CRC tumor growth via high AA microenvironment-induced enriched gram-negative microbes. Elimination of gram-negative microbe abolishes FADS1 effect. Mechanistically, gram-negative microbes activate TLR4/MYD88 pathway in CRC cells that contributes FADS1-AA axis to metabolize to prostaglandin E2 (PGE2). Cumulatively, we report a potential cancer-promoting mechanism of FADS1-AA axis in CRC that converts raising synthesized AA to PGE2 via modulating the intestinal microecology of gram-negative.

Free Fatty Acids from Cow Urine DMSO Fraction Induce Cell Death in Breast Cancer Cells without Affecting Normal GMSCs

Objective: The objective of this study was to explore the biological relevance of free fatty acids derived from cow urine DMSO fraction (CUDF) by employing in vitro and in silico approaches. Background: Metabolic heterogeneity at the intra- and intercellular levels contributes to the metabolic plasticity of cancer cells during drug-induced response. Free fatty acid (FFA) availability at intra- and intercellular levels is related to tumor heterogeneity at interpatient and xeno-heterogeneity levels. Methods: We collected fresh urine from healthy cows and subjected it to fractionation in DMSO using drying, vortexing, and centrifugation. Finally, the sterile filtrate of cow urine DMSO fraction (CUDF) was evaluated for antiproliferative and proapoptotic effects in MCF-7 and ZR-75-1 breast cancer cells using routine cell-based assays. Intracellular metabolites were studied with the help of a novel in-house vertical tube gel electrophoresis (VTGE) method to reveal the nature of CUDF components in MCF-7 cells. Identified intracellular FFAs were studied for their molecular interactions with targeted receptor histone deacetylase (HDAC) using molecular docking and molecular dynamics (MD) simulations. Results: CUDF showed a significant reduction in cell viability and cell death in MCF-7 and ZR-75-1 breast cancer cells. Interestingly, FFAs tetracosanedioic acid, 13Z-docosenoic acid (erucic acid), nervonic acid, 3-hydroxy-tetradecanoic acid, and 3-hydroxcapric acid were found inside the treated MCF-7 cancer cells. These FFAs, including tetracosanedioic acid, indicated a specific affinity to HDAC at their inhibitory sites, similar to trichostatin A, a known inhibitor. Conclusions: This study reports on FFAs derived from CUDF as potential antiproliferative and pro-cell death agents against breast cancer cells. MD simulations hinted at tetracosanedioic acid and other FFAs as inhibitors of HDAC that could explain the observed effects of FFAs in cancer cells.

Gut microbiota, an emergent target to shape the efficiency of cancer therapy

It is now well-acknowledged that microbiota has a profound influence on both human health and illness. The gut microbiota has recently come to light as a crucial element that influences cancer through a variety of mechanisms. The connections between the microbiome and cancer therapy are further highlighted by a number of preclinical and clinical evidence, suggesting that these complicated interactions may vary by cancer type, treatment, or even by tumor stage. The paradoxical relationship between gut microbiota and cancer therapies is that in some cancers, the gut microbiota may be necessary to maintain therapeutic efficacy, whereas, in other cancers, gut microbiota depletion significantly increases efficacy. Actually, mounting research has shown that the gut microbiota plays a crucial role in regulating the host immune response and boosting the efficacy of anticancer medications like chemotherapy and immunotherapy. Therefore, gut microbiota modulation, which aims to restore gut microbial balance, is a viable technique for cancer prevention and therapy given the expanding understanding of how the gut microbiome regulates treatment response and contributes to carcinogenesis. This review will provide an outline of the gut microbiota's role in health and disease, along with a summary of the most recent research on how it may influence the effectiveness of various anticancer medicines and affect the growth of cancer. This study will next cover the newly developed microbiota-targeting strategies including prebiotics, probiotics, and fecal microbiota transplantation (FMT) to enhance anticancer therapy effectiveness, given its significance.

Disruption of the Gut Microbiota Confers Cisplatin Resistance in Epithelial Ovarian Cancer

Epithelial ovarian cancer (EOC) is the leading cause of gynecologic cancer death. Despite initial responses to intervention, up to 80% of patient tumors recur and require additional treatment. Retrospective clinical analysis of patients with ovarian cancer indicates antibiotic use during chemotherapy treatment is associated with poor overall survival. Here, we assessed whether antibiotic (ABX) treatment would impact growth of EOC and sensitivity to cisplatin. Immunocompetent or immunocompromised mice were given untreated control or ABX-containing (metronidazole, ampicillin, vancomycin, and neomycin) water prior to intraperitoneal injection with EOC cells, and cisplatin therapy was administered biweekly until endpoint. Tumor-bearing ABX-treated mice exhibited accelerated tumor growth and resistance to cisplatin therapy compared with control treatment. ABX treatment led to reduced apoptosis, increased DNA damage repair, and enhanced angiogenesis in cisplatin-treated tumors, and tumors from ABX-treated mice contained a higher frequency of cisplatin-augmented cancer stem cells than control mice. Stool analysis indicated nonresistant gut microbial species were disrupted by ABX treatment. Cecal transplants of microbiota derived from control-treated mice was sufficient to ameliorate chemoresistance and prolong survival of ABX-treated mice, indicative of a gut-derived tumor suppressor. Metabolomics analyses identified circulating gut-derived metabolites that were altered by ABX treatment and restored by recolonization, providing candidate metabolites that mediate the cross-talk between the gut microbiome and ovarian cancer. Collectively, these findings indicate that an intact microbiome functions as a tumor suppressor in EOC, and perturbation of the gut microbiota with ABX treatment promotes tumor growth and suppresses cisplatin sensitivity.

SIGNIFICANCE

Restoration of the gut microbiome, which is disrupted following antibiotic treatment, may help overcome platinum resistance in patients with epithelial ovarian cancer. See related commentary by Hawkins and Nephew, p. 4511.

Factors that influence the pancreatic and duodenal microbiome in patients undergoing pancreatic surgery

BACKGROUND/OBJECTIVES

This study examined the correlation between pancreatic microbiome and patients characteristics. Furthermore, we compared different duodenal materials to examine their reflection of the pancreatic microbiome.

METHODS

Patients undergoing pancreatic surgery were included in the study. Characteristics of those patients were prospectively registered and sterile pancreatic biopsies were collected during surgery. After completion of the resection, duodenal fluid, -tissue and -swab were collected. Bacterial DNA was extracted and analyzed with IS-pro assay.

RESULTS

Paired samples of 51 patients were available for evaluation, including pancreatic biopsies from all patients, 22 duodenal fluids, 21 duodenal swabs and 11 duodenal tissues. The pancreatic microbiome consisted mostly of Proteobacteria followed by Firmicutes, Actinobacteria, Fusobacteria and Verrucomicrobia (FAFV) and Bacteroidetes. On species level, Enterococcus faecalis, Escherichia coli, and Enterobacter-Klebsiella were most abundant. In pancreatic biopsies, the total bacterial load and Proteobacteria load were significantly higher in patients with biliary drainage (54618.0 vs 5623.5; 9119.0 vs 2067.1). Patients who used proton pump inhibitors had a significantly higher total bacterial load (115964.7 vs 8495.8), more FAFV (66862.9 vs 1890.1), more Proteobacteria (24245.9 vs 2951.4) and more Bacteroidetes (542.5 vs 25.8). The head of the pancreas contained significantly more bacteria (21193.4 vs 2096.8) and more FAFV (5225.7 vs 19.0) compared to the tail, regardless of biliary drainage. Furthermore, the microbiome of all duodenal materials showed a weak correlation with the pancreatic microbiome.

CONCLUSION

Biliary drainage, use of proton pump inhibitors, and anatomic location of the pancreatic biopsy influence the pancreatic microbiome. Furthermore, the duodenal microbiome does not suffice as a surrogate for the pancreatic microbiome.

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 New Approach to Imaging and Rapid Microbiome Identification for Prostate Cancer Patients Undergoing Radiotherapy

(1) Background: Little is known about the impact of urinary microflora, in particular, its effects on side effects after radiotherapy. The use of mass spectrometry identification method (MALDI) may bring a new look at the issue of the composition and significance of the urinary microbiome. This study aimed to use the mass spectrometry identification method (MALDI) to identify the microbiome of urine samples collected from 50 irradiated prostate cancer patients. (2) Methods: Blood and urine samples were collected before gold marker implantation, at the start and last day of radiotherapy, 1, 4 months after. Patients do not always collect the urine from the midstream; therefore, samples were collected from the first void and midstream in 12 patients for MALDI analysis; in the remaining 38 patients—from the midstream void for MALDI and biochemical analysis. (3) Results: Microorganisms were present in 140/181 urine samples. We found 33 different species 3G(−) and 30G(+). The most frequently isolated strains were: Staphylococcus haemolyticus, Staphylococcus epidermidis, Staphylococcus hominis, Enterococcus faecalis, and Micrococcus luteus. When comparing the type of urine samples, bacteria were more common in samples from the first-void urine than from the midstream one. The absence of bacteria was found in 12.2% of samples from the first-void urine and in 24.7% from the midstream. There was no difference in the total incidence of species between streams (p = 0.85). Before fiducial implantation, the total number of detected bacterial species was significantly higher in comparison to the end of radiotherapy (p = 0.038), indicating that the administered therapy resulted in depleting the local microbiome. One month after radiotherapy, an increase in the number of isolated bacteria was observed. The number of bacterial species in urine did not correlate with blood parameters. The presence of leukocytes (p = 0.013) and proteins (p = 0.004) in urine was related to a greater variety of bacteria found in urine specimens. (4) Conclusions: We obtained a similar spectrum of bacteria from the initial and middle urine streams. We also showed that there is a change in bacteria species affected by the treatment of prostate cancer patients, with both antibiotics before gold fiducial implantation and radiotherapy.

Fecal Microbes Associated with the Outcomes After Esophagectomy in Patients with Esophageal Cancer

BACKGROUND

Although accumulating evidence suggests that an imbalanced gut microbiota leads to cancer progression, few studies demonstrated the implication in patients who underwent oncologic esophagectomy. This study aimed to elucidate the association between gut microbes and the outcomes after oncologic esophagectomy, as well as the host's inflammatory/nutritional status.

METHODS

Overall, 783 consecutive patients who underwent oncologic esophagectomy were eligible. We investigated the microbiota detected by fecal culture tests and then assessed the association between the gut microbiota and patient characteristics, short-term outcomes, and long-term survival.

RESULTS

Seventeen different species could be cultivated. We comprehensively examined the impact of each detected microbe on survival. The presence of Bacillus species (Bacillus sp.; 26.8%) was associated with favorable prognosis on overall and cancer-specific survival (p = 0.02 and 0.02, respectively). Conversely, the presence of Proteus mirabilis (P. mirabilis; 3.4%) was associated with unfavorable overall and recurrence-free survivals (p = 0.02 and < 0.01, respectively). Multivariate analysis showed that the presence of P. mirabilis was one of the independent prognostic factors for poor recurrence-free survival (p < 0.01). Patients with Bacillus sp. had lower modified Glasgow prognostic score and better response to preoperative treatment than those without (p = 0.01 and 0.03, respectively). Meanwhile, patients with P. mirabilis were significantly associated with higher systemic inflammation scores and increased postoperative pneumonia incidence than those without (p = 0.01 and 0.02, respectively).

CONCLUSIONS

Preoperative fecal microbiota was associated with the host's inflammatory and nutritional status and may influence the outcomes after oncologic esophagectomy.

New Developments and Opportunities of Microbiota in Treating Breast Cancers

Despite the prevalence of breast cancer (BC), over half of BC cases are unrelated to known risk factors, which highlights the importance of uncovering more cancer-related factors. Currently, the microbiota has been proven to be a potent modulator of the tumor environment in BC, which regulates the immune balance in tumor-related networks. Through a large amount of data accumulation, the microbiota has shown many possibilities to reveal more insights into the development or control of BC. To expand the potential benefits of patients with BC, this study discusses the distribution profile and the effect mechanism of BC-related microbiota on tumors and further discusses its impact on different tumor therapies. Finally, we summarize the possibility of targeting microbiological therapies to improve BC treatment or in combination with other therapies.

Biochemical and Metabolical Pathways Associated with Microbiota-Derived Butyrate in Colorectal Cancer and Omega-3 Fatty Acids Implications: A Narrative Review

Knowledge regarding the influence of the microbial community in cancer promotion or protection has expanded even more through the study of bacterial metabolic products and how they can modulate cancer risk, which represents an extremely challenging approach for the relationship between intestinal microbiota and colorectal cancer (CRC). This review discusses research progress on the effect of bacterial dysbiosis from a metabolic point of view, particularly on the biochemical mechanisms of butyrate, one of the main short chain fatty acids (SCFAs) with anti-inflammatory and anti-tumor properties in CRC. Increased daily intake of omega-3 polyunsaturated fatty acids (PUFAs) significantly increases the density of bacteria that are known to produce butyrate. Omega-3 PUFAs have been proposed as a treatment to prevent gut microbiota dysregulation and lower the risk or progression of CRC.

Dysbiosis of skin microbiome and gut microbiome in melanoma progression

Background

The microbiome alterations are associated with cancer growth and may influence the immune system and response to therapy. Particularly, the gut microbiome has been recently shown to modulate response to melanoma immunotherapy. However, the role of the skin microbiome has not been well explored in the skin tumour microenvironment and the link between the gut microbiome and skin microbiome has not been investigated in melanoma progression. Therefore, the aim of the present study was to examine associations between dysbiosis in the skin and gut microbiome and the melanoma growth using MeLiM porcine model of melanoma progression and spontaneous regression.

Results

Parallel analysis of cutaneous microbiota and faecal microbiota of the same individuals was performed in 8 to 12 weeks old MeLiM piglets. The bacterial composition of samples was analysed by high throughput sequencing of the V4-V5 region of the 16S rRNA gene. A significant difference in microbiome diversity and richness between melanoma tissue and healthy skin and between the faecal microbiome of MeLiM piglets and control piglets were observed. Both Principal Coordinate Analysis and Non-metric multidimensional scaling revealed dissimilarities between different bacterial communities. Linear discriminant analysis effect size at the genus level determined different potential biomarkers in multiple bacterial communities. Lactobacillus, Clostridium sensu stricto 1 and Corynebacterium 1 were the most discriminately higher genera in the healthy skin microbiome, while Fusobacterium, Trueperella, Staphylococcus, Streptococcus and Bacteroides were discriminately abundant in melanoma tissue microbiome. Bacteroides, Fusobacterium and Escherichia-Shigella were associated with the faecal microbiota of MeLiM piglets. Potential functional pathways analysis based on the KEGG database indicated significant differences in the predicted profile metabolisms between the healthy skin microbiome and melanoma tissue microbiome. The faecal microbiome of MeLiM piglets was enriched by genes related to membrane transports pathways allowing for the increase of intestinal permeability and alteration of the intestinal mucosal barrier.

Conclusion

The associations between melanoma progression and dysbiosis in the skin microbiome as well as dysbiosis in the gut microbiome were identified. Results provide promising information for further studies on the local skin and gut microbiome involvement in melanoma progression and may support the development of new therapeutic approaches.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-022-02458-5.

Dietary Patterns and Associated Microbiome Changes that Promote Oncogenesis

The recent increases in cancer incidences have been linked to lifestyle changes that result in obesity and metabolic syndrome. It is now evident that these trends are associated with the profound changes that occur in the intestinal microbiome, producing altered microbial population signatures that interact, directly or indirectly, with potentially pro-carcinogenic molecular pathways of transcription, proliferation, and inflammation. The effects of the entire gut microbial population on overall health are complex, but individual bacteria are known to play important and definable roles. Recent detailed examinations of a large number of subjects show a tight correlation between habitual diets, fecal microbiome signatures, and markers of metabolic health. Diets that score higher in healthfulness or diversity such as plant-based diets, have altered ratios of specific bacteria, including an increase in short-chain fatty acid producers, which in turn have been linked to improved metabolic markers and lowered cancer risk. Contrarily, numerous studies have implicated less healthy, lower-scoring diets such as the Western diet with reduced intestinal epithelial defenses and promotion of specific bacteria that affect carcinogenic pathways. In this review, we will describe how different dietary patterns affect microbial populations in the gut and illustrate the subsequent impact of bacterial products and metabolites on molecular pathways of cancer development, both locally in the gut and systemically in distant organs.

Oral microbiome associated with lymph node metastasis in oral squamous cell carcinoma

Oral microbiota can alter cancer susceptibility and progression by modulating metabolism and inflammation. We assessed the association between the oral microbiome and lymph node (LN) metastasis in oral squamous cell carcinoma (OSCC). We collected a total of 54 saliva samples from patients with OSCC before surgery. LN metastasis was assessed based on postoperative pathological examination. We used QIIME2, linear discriminant analysis effect size (LEfSe), and PICRUSt2 methods to analyze microbial dysbiosis. A random forest classifier was used to assess whether the oral microbiome could predict LN metastasis. Among the 54 OSCC samples, 20 had LN metastasis, and 34 had no evidence of metastasis. There was a significant difference in β-diversity between the metastasis and no metastasis groups. Through LEfSe analysis, the metastasis group was enriched in the genera Prevotella, Stomatobaculum, Bifidobacterium, Peptostreptococcaceae, Shuttleworthia and Finegoldia. Pathways related to signal peptidase II were predominant in the no metastasis group. The RF model showed a modestly high accuracy for predicting metastasis. Differences in microbial community composition and functions were observed in the oral microbiome of patients with OSCC with and without LN metastasis. However, the finding that specific taxa may be associated with LN metastasis should be verified in a further prospective study.

Metabolomics-Microbiome Crosstalk in the Breast Cancer Microenvironment

Breast cancer, the most frequent cancer diagnosed among females, is associated with a high mortality rate worldwide. Alterations in the microbiota have been linked with breast cancer development, suggesting the possibility of discovering disease biomarkers. Metabolomics has emerged as an advanced promising analytical approach for profiling metabolic features associated with breast cancer subtypes, disease progression, and response to treatment. The microenvironment compromises non-cancerous cells such as fibroblasts and influences cancer progression with apparent phenotypes. This review discusses the role of metabolomics in studying metabolic dysregulation in breast cancer caused by the effect of the tumor microenvironment on multiple cells such as immune cells, fibroblasts, adipocytes, etc. Breast tumor cells have a unique metabolic profile through the elevation of glycolysis and the tricarboxylic acid cycle metabolism. This metabolic profile is highly sensitive to microbiota activity in the breast tissue microenvironment. Metabolomics shows great potential as a tool for monitoring metabolic dysregulation in tissue and associating the findings with microbiome expression.

The effects of periodontitis associated microbiota on the development of oral squamous cell carcinoma

Epidemiological data have shown that periodontal bacterial infection, periodontitis, and oral squamous cell carcinoma have close relationship on the disease progress and risk. However, the specific role of periodontal microbes and their mechanism in the development of oral squamous cell carcinoma is not yet clear. In our previous work, metagenomic Illumina Mi-seq analysis was used to identify tstructure and abundance of periodontital microbiome. Accoding to the results, we used Porphyromonas.spp. and Fusobacterium.spp. as the periodontitis positive microbiota; Neisseria.spp and Corynebacterium.spp as periodontitis negative microbiota (their average relative abundance were >5%). These representative strains of the above genus were used to infect OSCC cells to explore their effect on tumor cell biology behavior, and detect the expression level of the gene in related to inflammation, migration, invasion and cell cycle. We find that periodontitis positive correlated microbiota had a promoting effect on the development of oral squamous cell carcinoma in vitro by regulating mRNA and protein expression of IL-6, IL-8, MMP-9 and Cyclin-D1. Periodontitis negative correlated microbiota had suppression effect on the development of oral squamous cell carcinoma in vitro analysis.

The intratumoural microbiota in cancer: new insights from inside

The human body harbors a vast array of microbiota that modulates host pathophysiological processes and modifies the risk of diseases including cancer. With the advent of metagenomic sequencing studies, the intratumoural microbiota has been found as a component of the tumor microenvironment, imperceptibly affecting the tumor progression and response to current antitumor treatments. The underlying carcinogenic mechanisms of intratumoural microbiota, mainly including inducing DNA damages, activating oncogenic signaling pathways and suppressing the immune response, differ significantly in varied organs and are not fully understood. Some native or genetically engineered microbial species can specifically accumulate and replicate within tumors to initiate antitumor immunity, which will be conducive to pursue precise cancer therapies. In this review, we summarized the community characteristics and therapeutic potential of intratumoural microbiota across diverse tumor types. It may provide new insights for a better understanding of tumor biology and hint at the significance of manipulating intratumoural microbiota.

The Role of Respiratory Microbiota in Lung Cancer

Recently, the impact of microorganisms on tumor growth and metastasis has attracted great attention. The pathogenesis and progression of lung cancer are related to an increase in respiratory bacterial load as well as changes in the bacterial community because the microbiota affects tumors in many ways, including canceration, metastasis, angiogenesis, and treatment. The microbiota may increase tumor susceptibility by altering metabolism and immune responses, promoting inflammation, and increasing toxic effects. The microbiota can regulate tumor metastasis by altering multiple cell signaling pathways and participate in tumor angiogenesis through vascular endothelial growth factors (VEGF), endothelial cells (ECs), inflammatory factors and inflammatory cells. Tumor angiogenesis not only maintains tumor growth at the primary site but also promotes tumor metastasis and invasion. Therefore, angiogenesis is an important mediator of the interaction between microorganisms and tumors. The microbiota also plays a part in antitumor therapy. Alteration of the microbiota caused by antibiotics can regulate tumor growth and metastasis. Moreover, the microbiota also influences the efficacy and toxicity of tumor immunotherapy and chemotherapy. Finally, the effects of air pollution, a risk factor for lung cancer, on microorganisms and the possible role of respiratory microorganisms in the effects of air pollution on lung cancer are discussed.

Microbiome Assisted Tumor Microenvironment: Emerging Target of Breast Cancer

The microbiome assisted tumor microenvironment (TME) supports the tumors by modulating multiple mechanisms. Recent studies reported that microbiome dysbiosis is the main culprit of immune suppressive phenotypes of TME. Further, it has been documented that immune suppressive stimulate metastatic phenotype in TME via modulating signaling pathways, cell differentiation, and innate immune response. This review aims at providing comprehensive developments in microbiome and breast TME interface. The combination of microbiome and breast cancer, breast TME and microbiome or microbial dysbiosis, microbiome and risk of breast cancer, microbiome and phytochemicals or anticancer drugs were as used keywords to retrieve literature from PubMed, Google scholar, Scopus, Web of Science from 2015 onwards. Based on the literature, we presented the impact of TME assisted microbiome dysbiosis and estrobolome in breast cancer risk, drug resistance, and antitumor immunity. We have discussed the influence of antibiotics on the breast microbiome. we also presented the possible dietary phytochemicals that target microbiome dysbiosis to restore the tumor suppression immune environment in breast TME. We presented the microbiome as a possible marker for breast cancer diagnosis. This study will help in the identification of microbiome as a novel target and diagnostic markers and phytochemicals and microbiome metabolites for breast cancer treatment.

The Challenge of ICIs Resistance in Solid Tumours: Could Microbiota and Its Diversity Be Our Secret Weapon?

The human microbiota and its functional interaction with the human body were recently returned to the spotlight of the scientific community. In light of the extensive implementation of newer and increasingly precise genome sequencing technologies, bioinformatics, and culturomic, we now have an extraordinary ability to study the microorganisms that live within the human body. Most of the recent studies only focused on the interaction between the intestinal microbiota and one other factor. Considering the complexity of gut microbiota and its role in the pathogenesis of numerous cancers, our aim was to investigate how microbiota is affected by intestinal microenvironment and how microenvironment alterations may influence the response to immune checkpoint inhibitors (ICIs). In this context, we show how diet is emerging as a fundamental determinant of microbiota’s community structure and function. Particularly, we describe the role of certain dietary factors, as well as the use of probiotics, prebiotics, postbiotics, and antibiotics in modifying the human microbiota. The modulation of gut microbiota may be a secret weapon to potentiate the efficacy of immunotherapies. In addition, this review sheds new light on the possibility of administering fecal microbiota transplantation to modulate the gut microbiota in cancer treatment. These concepts and how these findings can be translated into the therapeutic response to cancer immunotherapies will be presented.

The Role of Gut Microbiota in Tumor Immunotherapy

Tumor immunotherapy is the fourth therapy after surgery, chemotherapy, and radiotherapy. It has made great breakthroughs in the treatment of some epithelial tumors and hematological tumors. However, its adverse reactions are common or even more serious, and the response rate in some solid tumors is not satisfactory. With the maturity of genomics and metabolomics technologies, the effect of intestinal microbiota in tumor development and treatment has gradually been recognized. The microbiota may affect tumor immunity by regulating the host immune system and tumor microenvironment. Some bacteria help fight tumors by activating immunity, while some bacteria mediate immunosuppression to help cancer cells escape from the immune system. More and more studies have revealed that the effects and complications of tumor immunotherapy are related to the composition of the gut microbiota. The composition of the intestinal microbiota that is sensitive to treatment or prone to adverse reactions has certain characteristics. These characteristics may be used as biomarkers to predict the prognosis of immunotherapy and may also be developed as “immune potentiators” to assist immunotherapy. Some clinical and preclinical studies have proved that microbial intervention, including microbial transplantation, can improve the sensitivity of immunotherapy or reduce adverse reactions to a certain extent. With the development of gene editing technology and nanotechnology, the design and development of engineered bacteria that contribute to immunotherapy has become a new research hotspot. Based on the relationship between the intestinal microbiota and immunotherapy, the correct mining of microbial information and the development of reasonable and feasible microbial intervention methods are expected to optimize tumor immunotherapy to a large extent and bring new breakthroughs in tumor treatment.

A Journey from Structure to Function of Bacterial Lipopolysaccharides

Lipopolysaccharide (LPS) is a crucial constituent of the outer membrane of most Gram-negative bacteria, playing a fundamental role in the protection of bacteria from environmental stress factors, in drug resistance, in pathogenesis, and in symbiosis. During the last decades, LPS has been thoroughly dissected, and massive information on this fascinating biomolecule is now available. In this Review, we will give the reader a third millennium update of the current knowledge of LPS with key information on the inherent peculiar carbohydrate chemistry due to often puzzling sugar residues that are uniquely found on it. Then, we will drive the reader through the complex and multifarious immunological outcomes that any given LPS can raise, which is strictly dependent on its chemical structure. Further, we will argue about issues that still remain unresolved and that would represent the immediate future of LPS research. It is critical to address these points to complete our notions on LPS chemistry, functions, and roles, in turn leading to innovative ways to manipulate the processes involving such a still controversial and intriguing biomolecule.

The Bone Marrow Niche in B-Cell Acute Lymphoblastic Leukemia: The Role of Microenvironment from Pre-Leukemia to Overt Leukemia

Genetic lesions predisposing to pediatric B-cell acute lymphoblastic leukemia (B-ALL) arise in utero, generating a clinically silent pre-leukemic phase. We here reviewed the role of the surrounding bone marrow (BM) microenvironment in the persistence and transformation of pre-leukemic clones into fully leukemic cells. In this context, inflammation has been highlighted as a crucial microenvironmental stimulus able to promote genetic instability, leading to the disease manifestation. Moreover, we focused on the cross-talk between the bulk of leukemic cells with the surrounding microenvironment, which creates a “corrupted” BM malignant niche, unfavorable for healthy hematopoietic precursors. In detail, several cell subsets, including stromal, endothelial cells, osteoblasts and immune cells, composing the peculiar leukemic niche, can actively interact with B-ALL blasts. Through deregulated molecular pathways they are able to influence leukemia development, survival, chemoresistance, migratory and invasive properties. The concept that the pre-leukemic and leukemic cell survival and evolution are strictly dependent both on genetic lesions and on the external signals coming from the microenvironment paves the way to a new idea of dual targeting therapeutic strategy.

The role of the microbiome in ovarian cancer: mechanistic insights into oncobiosis and to bacterial metabolite signaling

Ovarian cancer is characterized by dysbiosis, referred to as oncobiosis in neoplastic diseases. In ovarian cancer, oncobiosis was identified in numerous compartments, including the tumor tissue itself, the upper and lower female genital tract, serum, peritoneum, and the intestines. Colonization was linked to Gram-negative bacteria with high inflammatory potential. Local inflammation probably participates in the initiation and continuation of carcinogenesis. Furthermore, local bacterial colonies in the peritoneum may facilitate metastasis formation in ovarian cancer. Vaginal infections (e.g. Neisseria gonorrhoeae or Chlamydia trachomatis) increase the risk of developing ovarian cancer. Bacterial metabolites, produced by the healthy eubiome or the oncobiome, may exert autocrine, paracrine, and hormone-like effects, as was evidenced in breast cancer or pancreas adenocarcinoma. We discuss the possible involvement of lipopolysaccharides, lysophosphatides and tryptophan metabolites, as well as, short-chain fatty acids, secondary bile acids and polyamines in the carcinogenesis of ovarian cancer. We discuss the applicability of nutrients, antibiotics, and probiotics to harness the microbiome and support ovarian cancer therapy. The oncobiome and the most likely bacterial metabolites play vital roles in mediating the effectiveness of chemotherapy. Finally, we discuss the potential of oncobiotic changes as biomarkers for the diagnosis of ovarian cancer and microbial metabolites as possible adjuvant agents in therapy.

Immune System, Microbiota, and Microbial Metabolites: The Unresolved Triad in Colorectal Cancer Microenvironment

Colorectal cancer (CRC) is one of the most common cancers worldwide. As with other cancers, CRC is a multifactorial disease due to the combined effect of genetic and environmental factors. Most cases are sporadic, but a small proportion is hereditary, estimated at around 5-10%. In both, the tumor interacts with heterogeneous cell populations, such as endothelial, stromal, and immune cells, secreting different signals (cytokines, chemokines or growth factors) to generate a favorable tumor microenvironment for cancer cell invasion and metastasis. There is ample evidence that inflammatory processes have a role in carcinogenesis and tumor progression in CCR. Different profiles of cell activation of the tumor microenvironment can promote pro or anti-tumor pathways; hence they are studied as a key target for the control of cancer progression. Additionally, the intestinal mucosa is in close contact with a microorganism community, including bacteria, bacteriophages, viruses, archaea, and fungi composing the gut microbiota. Aberrant composition of this microbiota, together with alteration in the diet-derived microbial metabolites content (such as butyrate and polyamines) and environmental compounds has been related to CRC. Some bacteria, such as pks+ Escherichia coli or Fusobacterium nucleatum, are involved in colorectal carcinogenesis through different pathomechanisms including the induction of genetic mutations in epithelial cells and modulation of tumor microenvironment. Epithelial and immune cells from intestinal mucosa have Pattern-recognition receptors and G-protein coupled receptors (receptor of butyrate), suggesting that their activation can be regulated by intestinal microbiota and metabolites. In this review, we discuss how dynamics in the gut microbiota, their metabolites, and tumor microenvironment interplays in sporadic and hereditary CRC, modulating tumor progression.

The Association Between Inflammation and Immunosuppression: Implications for ICI Biomarker Development

Evasion of immune destruction is considered one of the hallmarks of cancer. Chronic inflammation can enable immune escape by suppressing immune surveillance and permitting the development of tumors and creating a tumor microenvironment that sustains cancer. This includes generating mechanisms that prevent the effectiveness of anti-tumor treatment including immune checkpoint inhibitor therapy. In this review, we explore the interplay of inflammation and immunosuppression, their effects on the tumor microenvironment, and their implications for immune checkpoint inhibitor therapy particularly in the context of predictive biomarkers for their use.

Exploring the Potential of Breast Microbiota as Biomarker for Breast Cancer and Therapeutic Response

Breast cancer tissue contains its own unique microbiota. Emerging preclinical data indicates that breast microbiota dysbiosis contributes to breast cancer initiation and progression. Furthermore, the breast microbiota may be a promising biomarker for treatment selection and prognosis. Differences in breast microbiota composition have been found between breast cancer subtypes and disease severities that may contribute to immunosuppression, enabling tumor cells to evade immune destruction. Interactions between breast microbiota, gut microbiota, and immune system are proposed, all forming potential targets to increase therapeutic efficacy. In addition, because the gut microbiota affects the host immune system and systemic availability of estrogen and bile acids known to influence tumor biology, gut microbiota modulation could be used to manipulate breast microbiota composition. Identifying breast and gut microbial compositions that respond positively to certain anticancer therapeutics could significantly reduce cancer burden. Additional research is needed to unravel the complexity of breast microbiota functioning and its interactions with the gut and the immune system. In this review, developments in the understanding of breast microbiota and its interaction with the immune system and the gut microbiota are discussed. Furthermore, the biomarker potential of breast microbiota is evaluated in conjunction with possible strategies to target microbiota in order to improve breast cancer treatment.

Oncolytic Adenoviruses for Cancer Therapy

Many immuno-therapeutic strategies are currently being developed to fight cancer. In this scenario, oncolytic adenoviruses (Onc.Ads) have an interesting role for their peculiar tumor selectivity, safety, and transgene-delivery capability. The major strength of the Onc.Ads is the extraordinary immunogenicity that leads to a strong T-cell response, which, together with the possibility of the delivery of a therapeutic transgene, could be more effective than current strategies. In this review, we travel in the adenovirus (Ads) and Onc.Ads world, focusing on a variety of strategies that can enhance Onc.Ads antitumoral efficacy, passing through tumor microenvironment modulation. Onc.Ads-based therapeutic strategies constitute additional weapons in the fight against cancer and appear to potentiate conventional and immune checkpoint inhibitors (ICIs)-based therapies leading to a promising scenario.

Research Progress of Pancreas-Related Microorganisms and Pancreatic Cancer

Pancreatic cancer is one of the most common digestive system cancers. Early diagnosis is difficult owing to the lack of specific symptoms and reliable biomarkers. The cause of pancreatic cancer remains ambiguous. Smoking, drinking, new-onset diabetes, and chronic pancreatitis have been proven to be associated with the occurrence of pancreatic cancer. In recent years, a large number of studies have clarified that a variety of microorganisms colonized in pancreatic cancer tissues are also closely related to the occurrence and development of pancreatic cancer, and the specific mechanisms include inflammatory induction, immune regulation, metabolism, and microenvironment changes caused by microorganism. The mechanism of action of the pancreatic colonized microbiome in the tumor microenvironment, as well as immunotherapy approaches require further study in order to find more evidence to explain the complex relationship between the pancreatic colonized microbiome and PDAC. Relevant studies targeting the microbiome may provide insight into the mechanisms of PDAC development and progression, improving treatment effectiveness and overall patient prognosis. In this article, we focus on the research relating to the microorganisms colonized in pancreatic cancer tissues, including viruses, bacteria, and fungi. We also highlight the microbial diversity in the occurrence, invasion, metastasis, treatment, and prognosis of pancreatic cancer in order to elucidate its significance in the early diagnosis and new therapeutic treatment of pancreatic cancer, which urgently need to be improved in clinical practice. The elimination or increase in diversity of the pancreatic microbiome is beneficial for prolonging the survival of PDAC patients, improving the response to chemotherapy drugs, and reducing tumor burden. The colonization of microorganisms in the pancreas may become a new hotspot in the diagnosis and treatment of pancreatic cancer.

Throat Microbial Community Structure and Functional Changes in Postsurgery Laryngeal Carcinoma Patients

The microbial community structure in the throat and its shift after laryngectomy in laryngeal squamous cell carcinoma (LSCC) patients were investigated. Thirty swab samples taken prior to laryngectomy (SLC), 18 samples 1 week after laryngectomy (SLCA1w), and 30 samples 24 weeks after laryngectomy (SLCA24w) from 30 LSCC patients were examined. Microbial diversity was profiled through sequencing the V3-V4 variable region of the 16S rRNA gene. Quantitative real-time PCR (qPCR) was used to validate the 16S rRNA sequence data for the V3-V4 region. The community structure and function of throat microbiota were assessed by PICRUSt (phylogenetic investigation of communities by reconstruction of unobserved states) analysis. Both alpha and beta diversity results showed significant differences in the throat microbiota of LSCC patients before and after laryngectomy (P < 0.05). The drinking index of the SLC group was positively associated with the genus abundance of Prevotella (P < 0.05). The SLCA1w group had lower abundances of Fusobacterium, Leptotrichia, Lachnoanaerobaculum, and Veillonella than the SLC group (P < 0.05). The SLCA24w group had higher abundances of Streptococcus and Leptotrichia as well as lower abundances of Fusobacterium and Alloprevotella than the SLC group (P < 0.05). The throat microbiomes of the SLC group could be implicated in human cancer signaling pathways, as evidenced by PICRUSt analysis (P < 0.05). Our study clarifies alterations in throat microbial community structure and function in LSCC patients during the perioperative period and postoperative recovery period.IMPORTANCE Laryngeal squamous cell carcinoma greatly impacts patients' lives, and noninvasive means of prognostic assessment are valuable in determining the effectiveness of laryngectomy. We set out to study the microbial structure changes in the throat before and after laryngectomy and found the gene functions of several throat bacteria to be associated with human cancer signaling pathways. Our findings may offer insights into the disease management of patients with laryngeal squamous cell carcinoma. We hope to provide a means of using molecular mechanisms to improve the prognosis of laryngeal cancer treatment and to facilitate relevant research.

The Microbiota of the Human Mammary Ecosystem

Human milk contains a dynamic and complex site-specific microbiome, which is not assembled in an aleatory way, formed by organized microbial consortia and networks. Presence of some genera, such as Staphylococcus, Streptococcus, Corynebacterium, Cutibacterium (formerly known as Propionibacterium), Lactobacillus, Lactococcus and Bifidobacterium, has been detected by both culture-dependent and culture-independent approaches. DNA from some gut-associated strict anaerobes has also been repeatedly found and some studies have revealed the presence of cells and/or nucleic acids from viruses, archaea, fungi and protozoa in human milk. Colostrum and milk microbes are transmitted to the infant and, therefore, they are among the first colonizers of the human gut. Still, the significance of human milk microbes in infant gut colonization remains an open question. Clinical studies trying to elucidate the question are confounded by the profound impact of non-microbial human milk components to intestinal microecology. Modifications in the microbiota of human milk may have biological consequences for infant colonization, metabolism, immune and neuroendocrine development, and for mammary health. However, the factors driving differences in the composition of the human milk microbiome remain poorly known. In addition to colostrum and milk, breast tissue in lactating and non-lactating women may also contain a microbiota, with implications in the pathogenesis of breast cancer and in some of the adverse outcomes associated with breast implants. This and other open issues, such as the origin of the human milk microbiome, and the current limitations and future prospects are addressed in this review.

Application and Prospects of Molecular Imaging in Immunotherapy

Recently, immunotherapies that target the interactions of programmed cell death 1 (PD-1) with its major ligands, programmed death ligand 1 (PD-L1) and programmed death ligand 2 (PD-L2), have achieved significant success. To date, several immune checkpoint inhibitors targeting the PD-1/PD-L1 pathway have been developed to treat melanoma, non-small cell lung cancer, head and neck cancer, renal cell carcinoma, and urothelial carcinoma. Despite promising outcomes with immunotherapy, there are many limitations to several current immune biomarkers for predicting immune benefits and to traditional imaging for evaluating the efficacy and prognosis of immunotherapy and monitoring adverse reactions. In this review, we recommend a novel imaging method, molecular imaging. This paper reviews the application and prospects of molecular imaging in the context of current immunotherapies in regard to the following aspects: 1) detecting the expression of PD-1/PD-L1; 2) evaluating the efficacy of immunotherapy; 3) assessing patient prognosis with immunotherapy; 4) monitoring the toxicity of immunotherapy; and 5) other targets imaging.