Intratumoral bacteria may elicit chemoresistance by metabolizing anticancer agents

Identifying the location-dependent adipose tissue bacterial DNA signatures in obese patients that predict body weight loss

Recent sets of evidence have described profiles of 16S rDNA sequences in host tissues, notably in fat pads that are significantly overrepresented and can serve as signatures of metabolic disease. However, these recent and original observations need to be further detailed and functionally defined. Here, using state-of-the-art targeted DNA sequencing and discriminant predictive approaches, we describe, from the longitudinal FLORINASH cohort of patients who underwent bariatric surgery, visceral, and subcutaneous fat pad-specific bacterial 16SrRNA signatures. The corresponding Porphyromonadaceae, Campylobacteraceae, Prevotellaceae, Actimomycetaceae, Veillonellaceae, Anaerivoracaceae, Fusobacteriaceae, and the Clostridium family XI 16SrRNA DNA segment profiles are signatures of the subcutaneous adipose depot while Pseudomonadaceae and Micrococcacecae, 16SrRNA DNA sequence profiles characterize the visceral adipose depot. In addition, we have further identified that a specific pre-bariatric surgery adipose tissue bacterial DNA signature predicts the efficacy of body weight loss in obese patients 5-10 years after the surgery. 16SrRNA signatures discriminate (ROC ~ 1) the patients who did not maintain bodyweight loss and those who did. Second, from the 16SrRNA sequences we infer potential pathways suggestive of catabolic biochemical activities that could be signatures of subcutaneous adipose depots that predict body weight loss.

Synergistic Potential of Antibiotics with Cancer Treatments

Intratumoral microbiota, the diverse community of microorganisms residing within tumor tissues, represent an emerging and intriguing field in cancer biology. These microbial populations are distinct from the well-studied gut microbiota, offering novel insights into tumor biology, cancer progression, and potential therapeutic interventions. Recent studies have explored the use of certain antibiotics to modulate intratumoral microbiota and enhance the efficacy of cancer therapies, showing promising results. Antibiotics can alter intratumoral microbiota's composition, which may have a major role in promoting cancer progression and immune evasion. Certain bacteria within tumors can promote immunosuppression and resistance to therapies. By targeting these bacteria, antibiotics can help create a more favorable environment for chemotherapy, targeted therapy, and immunotherapy to act effectively. Some bacteria within the tumor microenvironment produce immunosuppressive molecules that inhibit the activity of immune cells. The combination of antibiotics and other cancer therapies holds significant promise for creating a synergistic effect and enhancing the immune response against cancer. In this review, we analyze several preclinical studies that have been conducted to demonstrate the synergy between antibiotics and other cancer therapies and discuss possible clinical implications.

Anticarcinogenic effects of ursodeoxycholic acid in pancreatic adenocarcinoma cell models

Changes to the composition of the microbiome in neoplasia, is termed oncobiosis, may affect tumor behavior through the changes to the secretion of bacterial metabolites. In this study we show, that ursodeoxycholic acid (UDCA), a bacterial metabolite, has cytostatic properties in pancreatic adenocarcinoma cell (PDAC) models. UDCA in concentrations corresponding to the human serum reference range suppressed PDAC cell proliferation. UDCA inhibited the expression of epithelial mesenchymal transition (EMT)-related markers and invasion capacity of PDAC cells. UDCA treatment increased oxidative/nitrosative stress by reducing the expression of nuclear factor, erythroid 2-like 2 (NRF2), inducing inducible nitric oxide synthase (iNOS) and nitrotyrosine levels and enhancing lipid peroxidation. Furthermore, UDCA reduced the expression of cancer stem cell markers and the proportion of cancer stem cells. Suppression of oxidative stress by antioxidants, blunted the UDCA-induced reduction in cancer stemness. Finally, we showed that UDCA induced mitochondrial oxidative metabolism. UDCA did not modulate the effectiveness of chemotherapy agents used in the chemotherapy treatment of pancreatic adenocarcinoma. The antineoplastic effects of UDCA, observed here, may contribute to the induction of cytostasis in PDAC cell models by providing a more oxidative/nitrosative environment.

Crosstalk Between the Intratumoral Microbiota and the Tumor Microenvironment: New Frontiers in Solid Tumor Progression and Treatment

BACKGROUND

The microbiota plays a significant role in the tumor microenvironment, and its impact on tumor development and treatment outcome cannot be overlooked. Thus, it is essential to comprehend the interactions between the microbiota and the tumor microenvironment.

RECENT FINDINGS

With the advent of next-generation sequencing, microbiota research has advanced significantly in recent years. The interaction between the intratumoral microbiota and the tumor microenvironment is an emerging area of research that holds great promise for understanding and treating solid tumor progression. This crosstalk between the intratumoral microbiota and the tumor microenvironment is a complex process that involves a multitude of factors, including the immune system, cellular signaling pathways, and metabolic processes. The origin of the intratumoral microbiota differs between various solid tumor, and the quantity and diversity of intratumoral microbiota also fluctuate significantly within each solid tumor.

CONCLUSION

The aim of this review is to provide a detailed summary of the intratumoral microbiota in various types of solid tumors. This will include an analysis of their origins, differences, and how they impact the progression of solid tumors. Furthermore, we will emphasize the significant potential that the intratumoral microbiota holds for the diagnosis and treatment of solid tumors.

Intratumoral Microbiota: Insights from Anatomical, Molecular, and Clinical Perspectives

The human microbiota represents a heterogeneous microbial community composed of several commensal, symbiotic, and even pathogenic microorganisms colonizing both the external and internal body surfaces. Despite the term "microbiota" being commonly used to identify microorganisms inhabiting the gut, several pieces of evidence suggest the presence of different microbiota physiologically colonizing other organs. In this context, several studies have also confirmed that microbes are integral components of tumor tissue in different types of cancer, constituting the so-called "intratumoral microbiota". The intratumoral microbiota is closely related to the occurrence and development of cancer as well as to the efficacy of anticancer treatments. Indeed, intratumoral microbiota can contribute to carcinogenesis and metastasis formation as some microbes can directly cause DNA damage, while others can induce the activation of proinflammatory responses or oncogenic pathways and alter the tumor microenvironment (TME). All these characteristics make the intratumoral microbiota an interesting topic to investigate for both diagnostic and prognostic purposes in order to improve the management of cancer patients. This review aims to gather the most recent data on the role of the intratumoral microbiota in cancer development, progression, and response to treatment, as well as its potential diagnostic and prognostic value.

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.

Radiotherapy and immunology

The majority of cancer patients receive radiotherapy during the course of treatment, delivered with curative intent for local tumor control or as part of a multimodality regimen aimed at eliminating distant metastasis. A major focus of research has been DNA damage; however, in the past two decades, emphasis has shifted to the important role the immune system plays in radiotherapy-induced anti-tumor effects. Radiotherapy reprograms the tumor microenvironment, triggering DNA and RNA sensing cascades that activate innate immunity and ultimately enhance adaptive immunity. In opposition, radiotherapy also induces suppression of anti-tumor immunity, including recruitment of regulatory T cells, myeloid-derived suppressor cells, and suppressive macrophages. The balance of pro- and anti-tumor immunity is regulated in part by radiotherapy-induced chemokines and cytokines. Microbiota can also influence radiotherapy outcomes and is under clinical investigation. Blockade of the PD-1/PD-L1 axis and CTLA-4 has been extensively investigated in combination with radiotherapy; we include a review of clinical trials involving inhibition of these immune checkpoints and radiotherapy.

Cytostatic Bacterial Metabolites Interfere with 5-Fluorouracil, Doxorubicin and Paclitaxel Efficiency in 4T1 Breast Cancer Cells

The microbiome is capable of modulating the bioavailability of chemotherapy drugs, mainly due to metabolizing these agents. Multiple cytostatic bacterial metabolites were recently identified that have cytostatic effects on cancer cells. In this study, we addressed the question of whether a set of cytostatic bacterial metabolites (cadaverine, indolepropionic acid and indoxylsulfate) can interfere with the cytostatic effects of the chemotherapy agents used in the management of breast cancer (doxorubicin, gemcitabine, irinotecan, methotrexate, rucaparib, 5-fluorouracil and paclitaxel). The chemotherapy drugs were applied in a wide concentration range to which a bacterial metabolite was added in a concentration within its serum reference range, and the effects on cell proliferation were assessed. There was no interference between gemcitabine, irinotecan, methotrexate or rucaparib and the bacterial metabolites. Nevertheless, cadaverine and indolepropionic acid modulated the Hill coefficient of the inhibitory curve of doxorubicin and 5-fluorouracil. Changes to the Hill coefficient implicate alterations to the kinetics of the binding of the chemotherapy agents to their targets. These effects have an unpredictable significance from the clinical or pharmacological perspective. Importantly, indolepropionic acid decreased the IC50 value of paclitaxel, which is a potentially advantageous combination.

A Holistic Perspective on Living Aggregate

Aggregate is one of the most extensive existing modes of matters in the world. Besides the research objectives of inanimate systems in physical science, the entities in life science can be regarded as living aggregates, which are far from being thoroughly understood despite the great advances in molecular biology. Molecular biology follows the research philosophy of reductionism, which generally reduces the whole into parts to study. Although reductionism benefits the understanding of molecular behaviors, it encounters limitations when extending to the aggregate level. Holism is another epistemology comparable to reductionism, which studies objectives at the aggregate level, emphasizing the interactions and synergetic/antagonistic effects of a group of composed single entities in determining the characteristics of a whole. As a representative of holism, aggregation-induced emission (AIE) materials have made great achievements in the past two decades in both physical and life science. In particular, the unique properties of AIE materials endow them with in situ and real-time visual methods to investigate the inconsistency between microscopic molecules and macroscopic substances, offering researchers excellent toolkits to study living aggregates. The applications of AIE materials in life science are still in their infancy and worth expanding. In this Perspective, we summarize the research progress of AIE materials in unveiling some phenomena and processes of living systems, aiming to provide a general research approach from the viewpoint of holism. At last, insights into what we can do in the near future are also raised and discussed.

Intratumoral microorganisms in tumors of the digestive system

Tumors of the digestive system pose a significant threat to human health and longevity. These tumors are associated with high morbidity and mortality rates, leading to a heavy economic burden on healthcare systems. Several intratumoral microorganisms are present in digestive system tumors, and their sources and abundance display significant heterogeneity depending on the specific tumor subtype. These microbes have a complex and precise function in the neoplasm. They can facilitate tumor growth through various mechanisms, such as inducing DNA damage, influencing the antitumor immune response, and promoting the degradation of chemotherapy drugs. Therefore, these microorganisms can be targeted to inhibit tumor progression for improving overall patient prognosis. This review focuses on the current research progress on microorganisms present in the digestive system tumors and how they influence the initiation, progression, and prognosis of tumors. Furthermore, the primary sources and constituents of tumor microbiome are delineated. Finally, we summarize the application potential of intratumoral microbes in the diagnosis, treatment, and prognosis prediction of digestive system tumors. Video Abstract.

Overcoming Microbiome-Acquired Gemcitabine Resistance in Pancreatic Ductal Adenocarcinoma

Gastrointestinal cancers (GICs) are one of the most recurrent diseases in the world. Among all GICs, pancreatic cancer (PC) is one of the deadliest and continues to disrupt people's lives worldwide. The most frequent pancreatic cancer type is pancreatic ductal adenocarcinoma (PDAC), representing 90 to 95% of all pancreatic malignancies. PC is one of the cancers with the worst prognoses due to its non-specific symptoms that lead to a late diagnosis, but also due to the high resistance it develops to anticancer drugs. Gemcitabine is a standard treatment option for PDAC, however, resistance to this anticancer drug develops very fast. The microbiome was recently classified as a cancer hallmark and has emerged in several studies detailing how it promotes drug resistance. However, this area of study still has seen very little development, and more answers will help in developing personalized medicine. PC is one of the cancers with the highest mortality rates; therefore, it is crucial to explore how the microbiome may mold the response to reference drugs used in PDAC, such as gemcitabine. In this article, we provide a review of what has already been investigated regarding the impact that the microbiome has on the development of PDAC in terms of its effect on the gemcitabine pathway, which may influence the response to gemcitabine. Therapeutic advances in this type of GIC could bring innovative solutions and more effective therapeutic strategies for other types of GIC, such as colorectal cancer (CRC), due to its close relation with the microbiome.

Intratumoral microbiota: implications for cancer onset, progression, and therapy

Significant advancements have been made in comprehending the interactions between the microbiome and cancer. However, prevailing research predominantly directs its focus toward the gut microbiome, affording limited consideration to the interactions of intratumoral microbiota and tumors. Within the tumor microenvironment (TME), the intratumoral microbiome and its associated products wield regulatory influence, directing the modulation of cancer cell properties and impacting immune system functionality. However, to grasp a more profound insight into the intratumoral microbiota in cancer, further research into its underlying mechanisms is necessary. In this review, we delve into the intricate associations between intratumoral microbiota and cancer, with a specific focus on elucidating the significant contribution of intratumoral microbiota to the onset and advancement of cancer. Notably, we provide a detailed exploration of therapeutic advances facilitated by intratumoral microbiota, offering insights into recent developments in this burgeoning field.

Microbiome and pancreatic cancer: time to think about chemotherapy

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive cancer characterized by late diagnosis, rapid progression, and a high mortality rate. Its complex biology, characterized by a dense, stromal tumor environment with an immunosuppressive milieu, contributes to resistance against standard treatments like chemotherapy and radiation. This comprehensive review explores the dynamic role of the microbiome in modulating chemotherapy efficacy and outcomes in PDAC. It delves into the microbiome's impact on drug metabolism and resistance, and the interaction between microbial elements, drugs, and human biology. We also highlight the significance of specific bacterial species and microbial enzymes in influencing drug action and the immune response in the tumor microenvironment. Cutting-edge methodologies, including artificial intelligence, low-biomass microbiome analysis and patient-derived organoid models, are discussed, offering insights into the nuanced interactions between microbes and cancer cells. The potential of microbiome-based interventions as adjuncts to conventional PDAC treatments are discussed, paving the way for personalized therapy approaches. This review synthesizes recent research to provide an in-depth understanding of how the microbiome affects chemotherapy efficacy. It focuses on elucidating key mechanisms and identifying existing knowledge gaps. Addressing these gaps is crucial for enhancing personalized medicine and refining cancer treatment strategies, ultimately improving patient outcomes.

Pharmacomicrobiomics of cell-cycle specific anti-cancer drugs - is it a new perspective for personalized treatment of cancer patients?

Intestinal bacteria are equipped with an enzyme apparatus that is involved in the active biotransformation of xenobiotics, including drugs. Pharmacomicrobiomics, a new area of pharmacology, analyses interactions between bacteria and xenobiotics. However, there is another side to the coin. Pharmacotherapeutic agents can significantly modify the microbiota, which consequently affects their efficacy. In this review, we comprehensively gathered scientific evidence on the interplay between anticancer therapies and gut microbes. We also underlined how such interactions might impact the host response to a given therapy. We discuss the possibility of modulating the gut microbiota to increase the effectiveness/decrease the incidence of adverse events during tumor therapy. The anticipation of the future brings new evidence that gut microbiota is a target of interest to increase the efficacy of therapy.

Bacterial immunotherapy: is it a weapon in our arsenal in the fight against cancer?

Advances in understanding the genetic basis of cancer have driven alternative treatment approaches. Recent findings have demonstrated the potential of bacteria and it's components to serve as robust theranostic agents for cancer eradication. Compared to traditional cancer therapies like surgery, chemotherapy, radiotherapy, bacteria mediated tumor therapy has exhibited superior cancer suppressing property which is attributed a lot to it's tumor proliferating and accumulating characteristics. Genetically modified bacteria has reduced inherent toxicity and enhanced specificity towards tumor microenvironment. This anti- tumor activity of bacteria is attributed to its toxins and other active components from the cell membrane, cell wall and spores. Furthermore, bacterial genes can be regulated to express and deliver cytokines, antibodies and cancer therapeutics. Although there is less clinical data available, the pre- clinical research clearly indicates the feasibility and potential of bacteria- mediated cancer therapy.

The visceral adipose tissue bacterial microbiota provides a signature of obesity based on inferred metagenomic functions

BACKGROUND

Metabolic inflammation mediated obesity requires bacterial molecules to trigger immune and adipose cells leading to inflammation and adipose depot development. In addition to the well-established gut microbiota dysbiosis, a leaky gut has been identified in patients with obesity and animal models, characterized by the presence of a tissue microbiota in the adipose fat pads.

METHODS

To determine its potential role, we sequenced the bacterial 16 S rRNA genes in the visceral adipose depot of patients with obesity. Taking great care (surgical, biochemical, and bioinformatic) to avoid environmental contaminants. We performed statistical discriminant analyses to identify specific signatures and constructed network of interactions between variables.

RESULTS

The data showed that a specific 16SrRNA gene signature was composed of numerous bacterial families discriminating between lean versus patients with obesity and people with severe obesity. The main discriminant families were Burkholderiaceae, Yearsiniaceae, and Xanthomonadaceae, all of which were gram-negative. Interestingly, the Morganellaceae were totally absent from people without obesity while preponderant in all in patients with obesity. To generate hypotheses regarding their potential role, we inferred metabolic pathways from the 16SrRNA gene signatures. We identified several pathways associated with adenosyl-cobalamine previously described to be linked with adipose tissue development. We further identified chorismate biosynthesis, which is involved in aromatic amino-acid metabolism and could play a role in fat pad development. This innovative approach generates novel hypotheses regarding the gut to adipose tissue axis.

CONCLUSIONS

This innovative approach generates novel hypotheses regarding the gut to adipose tissue axis in obesity and notably the potential role of tissue microbiota.

Functional Assay for Measuring Bacterial Degradation of Gemcitabine Chemotherapy

Drug biotransformation by the host microbiome can impact the therapeutic success of treatment. In the context of cancer, drug degradation can take place within the microenvironment of the targeted tumor by intratumor bacteria. In pancreatic cancer, increased chemo-resistance against the frontline chemotherapy gemcitabine is thought to arise from drug degradation by the tumor microbiome. This bacterial-drug interaction highlights the need for developing rapid assays for monitoring bacterial gemcitabine breakdown. While chemical approaches such as high-performance liquid chromatography are suitable for this task, they require specialized equipment and expertise and are limited in throughput. Functional cell-based assays represent an alternate approach for performing this task. We developed a functional assay to monitor the rate of bacterial gemcitabine breakdown using a highly sensitive bacterial reporter strain. Our method relies on standard laboratory equipment and can be implemented at high throughput to monitor drug breakdown by hundreds of strains simultaneously. This functional assay can be readily adapted to monitor degradation of other drugs. Key features Quantification of gemcitabine breakdown by incubating bacteria that degrades the drug and subsequently testing the growth of a reporter strain on filtered supernatant. Use of an optimized reporter strain that was genetically engineered to be a non-degrader strain and highly sensitive to gemcitabine. A high-throughput assay performed in microplates that can be adjusted for identifying bacteria with a fast or slow gemcitabine degradation rate. The assay results can be compared to results from a standard curve with known drug concentrations to quantify degradation rate.

Influence of the microbiota on the effectiveness and toxicity of oncological therapies, with a focus on chemotherapy

Recent studies have highlighted a possible correlation between microbiota composition and the pathogenesis of various oncological diseases. Also, many bacterial groups are now directly or indirectly associated with the capability of stimulating or inhibiting carcinogenic pathways. However, little is known about the importance and impact of microbiota patterns related to the efficacy and toxicity of cancer treatments. We have recently begun to understand how oncological therapies and the microbiota are closely interconnected and could influence each other. Chemotherapy effectiveness, for example, appears to be strongly influenced by the presence of some microorganisms capable of modulating the pharmacokinetics and pharmacodynamics of the compounds used, thus varying the real response and therefore the efficacy of the oncological treatment. Similarly, chemotherapeutic agents can modulate the microbiota with variations that could facilitate or avoid the onset of important side effects. This finding has or could have considerable relevance as it is possible that our ability to modulate and modify the microbial structure before, during, and after treatment could influence all the clinical parameters related to pharmacological treatments and, eventually, the prognosis of the disease.

Structure of gut microbiota and characteristics of fecal metabolites in patients with lung cancer

Objective

The gut micro-biome plays a pivotal role in the progression of lung cancer. However, the specific mechanisms by which the intestinal microbiota and its metabolites are involved in the lung cancer process remain unclear.

Method

Stool samples from 52 patients with lung cancer and 29 healthy control individuals were collected and subjected to 16S rRNA gene amplification sequencing and non-targeted gas/liquid chromatography-mass spectrometry metabolomics analysis. Then microbiota, metabolites and potential signaling pathways that may play an important role in the disease were filtered.

Results

Firmicutes, Clostridia, Bacteroidacea, Bacteroides, and Lachnospira showed a greater abundance in healthy controls. In contrast, the Ruminococcus gnavus(R.gnavus) was significantly upregulated in lung cancer patients. In this respect, the micro-biome of the squamous cell carcinoma(SCC)group demonstrated a relatively higher abundance of Proteobacteria, Gammaproteobacteria, Bacteroides,and Enterobacteriaceae, as well as higher abundances of Fusicatenibacter and Roseburia in adenocarcinoma(ADC) group. Metabolomic analysis showed significant alterations in fecal metabolites including including quinic acid, 3-hydroxybenzoic acid,1-methylhydantoin,3,4-dihydroxydrocinnamic acid and 3,4-dihydroxybenzeneacetic acid were significantly altered in lung cancer patients. Additionally, the R.gnavus and Fusicatenibacter of lung cancer were associated with multiple metabolite levels.

Conclusion

Our study provides essential guidance for a fundamental systematic and multilevel assessment of the contribution of gut micro-biome and their metabolites in lung cancer,which has great potential for understanding the pathogenesis of lung cancer and for better early prevention and targeted interventions.

The Interplay between Microbiota and Chemotherapy-Derived Metabolites in Breast Cancer

The most common cancer in women is breast cancer, which is also the second leading cause of death in this group. It is, however, important to note that some women will develop or will not develop breast cancer regardless of whether certain known risk factors are present. On the other hand, certain compounds are produced by bacteria in the gut, such as short-chain fatty acids, secondary bile acids, and other metabolites that may be linked to breast cancer development and mediate the chemotherapy response. Modeling the microbiota through dietary intervention and identifying metabolites directly associated with breast cancer and its complications may be useful to identify actionable targets and improve the effect of antiangiogenic therapies. Metabolomics is therefore a complementary approach to metagenomics for this purpose. As a result of the combination of both techniques, a better understanding of molecular biology and oncogenesis can be obtained. This article reviews recent literature about the influence of bacterial metabolites and chemotherapy metabolites in breast cancer patients, as well as the influence of diet.

New Treatment Options in Metastatic Pancreatic Cancer

Pancreatic cancer (PC) is the seventh leading cause of cancer death across the world. Poor prognosis of PC is associated with several factors, such as diagnosis at an advanced stage, early distant metastases, and remarkable resistance to most conventional treatment options. The pathogenesis of PC seems to be significantly more complicated than originally assumed, and findings in other solid tumours cannot be extrapolated to this malignancy. To develop effective treatment schemes prolonging patient survival, a multidirectional approach encompassing different aspects of the cancer is needed. Particular directions have been established; however, further studies bringing them all together and connecting the strengths of each therapy are needed. This review summarises the current literature and provides an overview of new or emerging therapeutic strategies for the more effective management of metastatic PC.

Evolved bacterial resistance to the chemotherapy gemcitabine modulates its efficacy in co-cultured cancer cells

Drug metabolism by the microbiome can influence anticancer treatment success. We previously suggested that chemotherapies with antimicrobial activity can select for adaptations in bacterial drug metabolism that can inadvertently influence the host's chemoresistance. We demonstrated that evolved resistance against fluoropyrimidine chemotherapy lowered its efficacy in worms feeding on drug-evolved bacteria (Rosener et al., 2020). Here, we examine a model system that captures local interactions that can occur in the tumor microenvironment. Gammaproteobacteria-colonizing pancreatic tumors can degrade the nucleoside-analog chemotherapy gemcitabine and, in doing so, can increase the tumor's chemoresistance. Using a genetic screen in Escherichia coli, we mapped all loss-of-function mutations conferring gemcitabine resistance. Surprisingly, we infer that one third of top resistance mutations increase or decrease bacterial drug breakdown and therefore can either lower or raise the gemcitabine load in the local environment. Experiments in three E. coli strains revealed that evolved adaptation converged to inactivation of the nucleoside permease NupC, an adaptation that increased the drug burden on co-cultured cancer cells. The two studies provide complementary insights on the potential impact of microbiome adaptation to chemotherapy by showing that bacteria-drug interactions can have local and systemic influence on drug activity.

The Multifaceted MEP Pathway: Towards New Therapeutic Perspectives

Isoprenoids, a diverse class of natural products, are present in all living organisms. Their two universal building blocks are synthesized via two independent pathways: the mevalonate pathway and the 2-C-methyl-ᴅ-erythritol 4-phosphate (MEP) pathway. The presence of the latter in pathogenic bacteria and its absence in humans make all its enzymes suitable targets for the development of novel antibacterial drugs. (E)-4-Hydroxy-3-methyl-but-2-enyl diphosphate (HMBPP), the last intermediate of this pathway, is a natural ligand for the human Vγ9Vδ2 T cells and the most potent natural phosphoantigen known to date. Moreover, 5-hydroxypentane-2,3-dione, a metabolite produced by Escherichia coli 1-deoxy-ᴅ-xylulose 5-phosphate synthase (DXS), the first enzyme of the MEP pathway, structurally resembles (S)-4,5-dihydroxy-2,3-pentanedione, a signal molecule implied in bacterial cell communication. In this review, we shed light on the diversity of potential uses of the MEP pathway in antibacterial therapies, starting with an overview of the antibacterials developed for each of its enzymes. Then, we provide insight into HMBPP, its synthetic analogs, and their prodrugs. Finally, we discuss the potential contribution of the MEP pathway to quorum sensing mechanisms. The MEP pathway, providing simultaneously antibacterial drug targets and potent immunostimulants, coupled with its potential role in bacterial cell-cell communication, opens new therapeutic perspectives.

Human liver microbiota modeling strategy at the early onset of fibrosis

BACKGROUND

Gut microbiota is involved in the development of liver diseases such as fibrosis. We and others identified that selected sets of gut bacterial DNA and bacteria translocate to tissues, notably the liver, to establish a non-infectious tissue microbiota composed of microbial DNA and a low frequency live bacteria. However, the precise set of bacterial DNA, and thereby the corresponding taxa associated with the early stages of fibrosis need to be identified. Furthermore, to overcome the impact of different group size and patient origins we adapted innovative statistical approaches. Liver samples with low liver fibrosis scores (F0, F1, F2), to study the early stages of the disease, were collected from Romania(n = 36), Austria(n = 10), Italy(n = 19), and Spain(n = 17). The 16S rRNA gene was sequenced. We considered the frequency, sparsity, unbalanced sample size between cohorts to identify taxonomic profiles and statistical differences.

RESULTS

Multivariate analyses, including adapted spectral clustering with L1-penalty fair-discriminant strategies, and predicted metagenomics were used to identify that 50% of liver taxa associated with the early stage fibrosis were Enterobacteriaceae, Pseudomonadaceae, Xanthobacteriaceae and Burkholderiaceae. The Flavobacteriaceae and Xanthobacteriaceae discriminated between F0 and F1. Predicted metagenomics analysis identified that the preQ0 biosynthesis and the potential pathways involving glucoryranose and glycogen degradation were negatively associated with liver fibrosis F1-F2 vs F0.

CONCLUSIONS

Without demonstrating causality, our results suggest first a role of bacterial translocation to the liver in the progression of fibrosis, notably at the earliest stages. Second, our statistical approach can identify microbial signatures and overcome issues regarding sample size differences, the impact of environment, and sets of analyses.

TRIAL REGISTRATION

TirguMECCH ROLIVER Prospective Cohort for the Identification of Liver Microbiota, registration 4065/2014. Registered 01 01 2014.

Intratumoral microbiota: roles in cancer initiation, development and therapeutic efficacy

Microorganisms, including bacteria, viruses, fungi, and other eukaryotes, play critical roles in human health. An altered microbiome can be associated with complex diseases. Intratumoral microbial components are found in multiple tumor tissues and are closely correlated with cancer initiation and development and therapy efficacy. The intratumoral microbiota may contribute to promotion of the initiation and progression of cancers by DNA mutations, activating carcinogenic pathways, promoting chronic inflammation, complement system, and initiating metastasis. Moreover, the intratumoral microbiota may not only enhance antitumor immunity via mechanisms including STING signaling activation, T and NK cell activation, TLS production, and intratumoral microbiota-derived antigen presenting, but also decrease antitumor immune responses and promote cancer progression through pathways including upregulation of ROS, promoting an anti-inflammatory environment, T cell inactivation, and immunosuppression. The effect of intratumoral microbiota on antitumor immunity is dependent on microbiota composition, crosstalk between microbiota and the cancer, and status of cancers. The intratumoral microbiota may regulate cancer cell physiology and the immune response by different signaling pathways, including ROS, β-catenin, TLR, ERK, NF-κB, and STING, among others. These viewpoints may help identify the microbiota as diagnosis or prognosis evaluation of cancers, and as new therapeutic strategy and potential therapeutic targets for cancer therapy.

The Microbiome in Pancreatic Cancer-Implications for Diagnosis and Precision Bacteriophage Therapy for This Low Survival Disease

While the mortality rates for many cancers have decreased due to improved detection and treatments, that of pancreatic cancer remains stubbornly high. The microbiome is an important factor in the progression of many cancers. Greater understanding of the microbiome in pancreatic cancer patients, as well as its manipulation, may assist in diagnosis and treatment of this disease. In this report we reviewed studies that compared microbiome changes in pancreatic cancer patients and non-cancer patients. We then identified which bacterial genera were most increased in relative abundance across the oral, pancreatic, duodenal, and faecal tissue microbiomes. In light of these findings, we discuss the potential for utilising these bacteria as diagnostic biomarkers, as well as their potential control using precision targeting with bacteriophages, in instances where a causal oncogenic link is made.

Bacterial infections in cancer: A bilateral relationship

Bacteria share a long commensal relationship with the human body. New findings, however, continue to unravel many complexities associated with this old alliance. In the past decades, the dysbiosis of human microbiome has been linked to tumorigenesis, and more recently to spontaneous colonization of existing tumors. The topic, however, remains open for debate as the claims for causative-prevailing dual characteristics of bacteria are mostly based on epidemiological evidence rather than robust mechanistic models. There are also no reviews linking the collective impact of bacteria in tumor microenvironments to the efficacy of cancer drugs, mechanisms of pathogen-initiated cancer and bacterial colonization, personalized nanomedicine, nanotechnology, and antimicrobial resistance. In this review, we provide a holistic overview of the bilateral relationship between cancer and bacteria covering all these aspects. Our collated evidence from the literature does not merely categorize bacteria as cancer causative or prevailing agents, but also critically highlights the gaps in the literature where more detailed studies may be required to reach such a conclusion. Arguments are made in favor of dual drug therapies that can simultaneously co-target bacteria and cancer cells to overcome drug resistance. Also discussed are the opportunities for leveraging the natural colonization and remission power of bacteria for cancer treatment. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Tumor-resident intracellular microbiota promotes metastatic colonization in breast cancer

Tumor-resident intracellular microbiota is an emerging tumor component that has been documented for a variety of cancer types with unclear biological functions. Here, we explored the functional significance of these intratumor bacteria, primarily using a murine spontaneous breast-tumor model MMTV-PyMT. We found that depletion of intratumor bacteria significantly reduced lung metastasis without affecting primary tumor growth. During metastatic colonization, intratumor bacteria carried by circulating tumor cells promoted host-cell survival by enhancing resistance to fluid shear stress by reorganizing actin cytoskeleton. We further showed that intratumor administration of selected bacteria strains isolated from tumor-resident microbiota promoted metastasis in two murine tumor models with significantly different levels of metastasis potential. Our findings suggest that tumor-resident microbiota, albeit at low biomass, play an important role in promoting cancer metastasis, intervention of which might therefore be worth exploring for advancing oncology care.

Role of biliary stent and neoadjuvant chemotherapy in the pancreatic tumor microbiome

BACKGROUND

Intra-tumor microbiota have been implicated in pancreatic ductal adenocarcinoma (PDAC) development, treatment response and post-treatment survivorship. Moreover, therapeutic interventions targeting microbiota may improve the response to chemotherapy and immunotherapy, further emphasizing the critical need to understand the origins of and growth of bacteria within the pancreatic tumor microenvironment. Here, we studied the role of several clinical factors on the bacterial colonization of PDAC.

RESULTS

We obtained matched tumor and normal pancreatic tissue specimens from 27 patients who had undergone surgical resection for PDAC between 2011 and 2015 from the University of Minnesota Biological Materials Procurement Network (BioNet). We found that 26 (48%) out of 54 pancreatic tissue samples harbored detectable bacterial communities using real-time PCR targeting the 16S rRNA gene. Bacterial colonization was detected significantly more frequently in samples from patients who had pancreatic head tumors, underwent Whipple procedure, or had preoperative biliary stent placement. There was also a significantly greater relative abundance of microbiota from the family Enterobacteriaceae among samples from patients who underwent biliary stent placement or neoadjuvant treatment with a combination of Gemcitabine and Paclitaxel.

CONCLUSIONS

These findings suggest that biliary stent placement and neoadjuvant chemotherapy are associated with specific alterations that promote the infiltration and growth of intra-tumor bacteria in the setting of PDAC. Further studies exploring whether specific bacterial communities could contribute to increased chemoresistance will be essential for optimizing medical therapies in the future.

Microbiome in drug resistance to colon cancer

Metagenomic analyses have revealed microbial dysbiosis in the gut of patients with colorectal cancer (CRC). The gut microbiota influences CRC via a variety of mechanisms, including microbial-derived factors such as metabolites or genotoxins. Pathogenic drivers and opportunistic passenger bacteria may underlie direct effect of the gut microbiota on carcinogenesis. We posit that metabolites generated by gut microbiota can influence CRC through a multitude of epigenetic or genetic effects on malignant transformation. A closer look at the cross talks between the commensals, epithelial cells, immune regulators etc., needs to be established with more substantiated studies. The recurrence of chemoresistant disease following therapy undoubtedly provides the impetus for morbidity and mortality; yet, the role of gut microbiome in drug resistance remains to be fully investigated. We review the current literature on microbial dysbiosis during CRC and discuss the mechanistic basis of CRC-associated bacteria in tumor initiation, progression and drug resistance.

Engineering Calreticulin-Targeting Monobodies to Detect Immunogenic Cell Death in Cancer Chemotherapy

Surface-exposed calreticulin (ecto-CRT) plays a crucial role in the phagocytic removal of apoptotic cells during immunotherapy. Ecto-CRT is an immunogenic signal induced in response to treatment with chemotherapeutic agents such as doxorubicin (DOX) and mitoxantrone (MTX), and two peptides (KLGFFKR (Integrin-α) and GQPMYGQPMY (CRT binding peptide 1, Hep-I)) are known to specifically bind CRT. To engineer CRT-specific monobodies as agents to detect immunogenic cell death (ICD), we fused these peptide sequences at the binding loops (BC and FG) of human fibronectin domain III (FN3). CRT-specific monobodies were purified from E. coli by affinity chromatography. Using these monobodies, ecto-CRT was evaluated in vitro, in cultured cancer cell lines (CT-26, MC-38, HeLa, and MDA-MB-231), or in mice after anticancer drug treatment. Monobodies with both peptide sequences (CRT3 and CRT4) showed higher binding to ecto-CRT than those with a single peptide sequence. The binding affinity of the Rluc8 fusion protein-engineered monobodies (CRT3-Rluc8 and CRT4-Rluc8) to CRT was about 8 nM, and the half-life in serum and tumor tissue was about 12 h. By flow cytometry and confocal immunofluorescence of cancer cell lines, and by in vivo optical bioluminescence imaging of tumor-bearing mice, CRT3-Rluc8 and CRT4-Rluc8 bound specifically to ecto-CRT and effectively detected pre-apoptotic cells after treatment with ICD-inducing agents (DOX and MTX) but not a non-ICD-inducing agent (gemcitabine). Using CRT-specific monobodies, it is possible to detect ecto-CRT induction in cancer cells in response to drug exposure. This technique may be used to predict the therapeutic efficiency of chemo- and immuno-therapeutics early during anticancer treatment.

Mycoplasma hyorhinis infection promotes tyrosine kinase inhibitor (TKI) resistance in lung adenocarcinoma patients

PURPOSE

To explore the relationship between Mycoplasma hyorhinis infection and tyrosine kinase inhibitor (TKI) resistance in lung adenocarcinoma patients.

METHODS

Mycoplasma hyorhinis infection can be verified with the monoclonal antibody PD4, which specifically recognizes a distinct protein of M. hyorhinis. Immunohistochemistry (IHC), using PD4 to detect M. hyorhinis, was performed on paraffin-embedded lung adenocarcinoma tissues of patients who had epidermal growth factor (EGFR) mutations and had received oral TKI. The number of patients enrolled in our study was 101. Assessments following TKI treatment were performed until objective disease progression or stable disease at the cutoff date was reached. In all of the patients, the primary endpoint was investigator-assessed progression-free survival (PFS).

RESULTS

Immunohistochemistry revealed that 61 of 101 cases (60.4%) of lung adenocarcinoma were positive for M. hyorhinis, which comprised of 31 low-positive cases and 30 high-positive cases; the remaining 40 cases (39.6%) were negative. The median PFS was significantly longer in the negative group [18 months (95% CI 14.15-21.85)] than in the low-positive group [10 months (95% CI 7.70-12.30); hazard ratio (HR) 4.095, 95% CI 2.254-7.438; p < 0.001] and in the high-positive group [4 months (95% CI 2.85-5.15); HR 31.703, 95% CI 14.425-69.678; p < 0.001]. The results of the subgroup analysis were satisfactory. The PFS benefit with negative M. hyorhinis infection was consistent across subgroups.

CONCLUSIONS

In this retrospective, exploratory analysis, M. hyorhinis infection significantly reduced PFS. With increased levels of M. hyorhinis infection, the progression of the disease was more advanced, likely due to the hydrolysis of TKI by M. hyorhinis. A strong correlation was found between M. hyorhinis infection and TKI resistance in lung adenocarcinoma. This study provides potent evidence that M. hyorhinis hydrolyses TKI and will assist in the research of related mechanisms in the future.

IMPLICATIONS FOR CANCER SURVIVORS

It provides an option to improve the efficacy of TKI, including strategies to decrease M. hyorhinis infection, thereby reducing long-term distress in TKI resistance patients with EGFR mutations.

Microbiome dysbiosis in lung cancer: from composition to therapy

The correlations between microbiota dysbiosis and cancer have gained extensive attention and been widely explored. As a leading cancer diagnosis worldwide, lung cancer poses a great threat to human health. The healthy human lungs are consistently exposed to external environment and harbor a specific pattern of microbiota, sharing many key pathological and physiological characteristics with the intestinal tract. Although previous findings uncovered the critical roles of microbiota in tumorigenesis and response to anticancer therapy, most of them were focused on the intestinal microbiota rather than lung microbiota. Notably, the considerable functions of microbiota in maintaining lung homeostasis should not be neglected as the microbiome dysbiosis may promote tumor development and progression through production of cytokines and toxins and multiple other pathways. Despite the fact that increasing studies have revealed the effect of microbiome on the induction of lung cancer and different disease status, the underlying mechanisms and potential therapeutic strategies remained unclear. Herein, we summarized the recent progresses about microbiome in lung cancer and further discussed the role of microbial communities in promoting lung cancer progression and the current status of therapeutic approaches targeting microbiome to alleviate and even cure lung cancer.

Commensal microbes and p53 in cancer progression

Aetiogenesis of cancer has not been fully determined. Recent advances have clearly defined a role for microenvironmental factors in cancer progression and initiation; in this context, microbiome has recently emerged with a number of reported correlative and causative links implicating alterations of commensal microbes in tumorigenesis. Bacteria appear to have the potential to directly alter physiological pathways of host cells and in specific circumstances, such as the mutation of the tumour suppressive factor p53, they can also directly switch the function of a gene from oncosuppressive to oncogenic. In this minireview, we report a number of examples on how commensal microbes alter the host cell biology, affecting the oncogenic process. We then discuss more in detail how interaction with the gut microbiome can affect the function of p53 mutant in the intestinal tumorigenesis.

Microbial dysbiosis and polyamine metabolism as predictive markers for early detection of pancreatic cancer

The lack of tools for early detection of pancreatic ductal adenocarcinoma (PDAC) is directly correlated with the abysmal survival rates in patients. In addition to several potential detection tools under active investigation, we tested the gut microbiome and its metabolic complement as one of the earliest detection tools that could be useful in patients at high risk for PDAC. We used a combination of 16s rRNA pyrosequencing and whole-genome sequencing of gut fecal microbiota in a genetically engineered PDAC murine model (KRASG12DTP53R172HPdxCre or KPC). Metabolic reconstruction of microbiome was done using the HUMAnN2 pipeline. Serum polyamine levels were measured from murine and patient samples using chromogenic assay. Our results showed a Proteobacterial and Firmicutes dominance in gut microbiota in early stages of PDAC development. Upon in silico reconstruction of active metabolic pathways within the altered microbial flora, polyamine and nucleotide biosynthetic pathways were significantly elevated. These metabolic products are known to be actively assimilated by the host and eventually utilized by rapidly dividing cells for proliferation validating their importance in the context of tumorigenesis. In KPC mice, as well as PDAC patients, we show significantly elevated serum polyamine concentrations. Therefore, at the early stages of tumorigenesis, there is a strong correlation between microbial changes and release of metabolites that foster host tumorigenesis, thereby fulfilling the 'vicious cycle hypothesis' of the role of microbiome in health and disease states. Our results provide a potential, precise, noninvasive tool for early detection of PDAC, which may result in improved outcomes.

Microenvironmental Determinants of Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) belongs to the most lethal solid tumors in humans. A histological hallmark feature of PDAC is the pronounced tumor microenvironment (TME) that dynamically evolves during tumor progression. The TME consists of different non-neoplastic cells such as cancer-associated fibroblasts, immune cells, endothelial cells, and neurons. Furthermore, abundant extracellular matrix components such as collagen and hyaluronic acid as well as matricellular proteins create a highly dynamic and hypovascular TME with multiple biochemical and physical interactions among the various cellular and acellular components that promote tumor progression and therapeutic resistance. In recent years, intensive research efforts have resulted in a significantly improved understanding of the biology and pathophysiology of the TME in PDAC, and novel stroma-targeted approaches are emerging that may help to improve the devastating prognosis of PDAC patients. However, none of anti-stromal therapies has been approved in patients so far, and there is still a large discrepancy between multiple successful preclinical results and subsequent failure in clinical trials. Furthermore, recent findings suggest that parts of the TME may also possess tumor-restraining properties rendering tailored therapies even more challenging.

Type 2 diabetes induced microbiome dysbiosis is associated with therapy resistance in pancreatic adenocarcinoma

Resistance to therapy is one of the major factors that contribute to dismal survival statistics in pancreatic cancer. While there are many tumor intrinsic and tumor microenvironment driven factors that contribute to therapy resistance, whether pre-existing metabolic diseases like type 2 diabetes (T2D) contribute to this has remained understudied. It is well accepted that hyperglycemia associated with type 2 diabetes changes the gut microbiome. Further, hyperglycemia also enriches for a "stem-like" population within the tumor. In the current study, we observed that in a T2D mouse model, the microbiome changed significantly as the hyperglycemia developed in these animals. Our results further showed that, tumors implanted in the T2D mice responded poorly to gemcitabine/paclitaxel (Gem/Pac) standard of care compared to those in the control group. A metabolomic reconstruction of the WGS of the gut microbiota further revealed that an enrichment of bacterial population involved in drug metabolism in the T2D group. Additionally, we also observed an increase in the CD133+ tumor cells population in the T2D model. These observations indicated that in an animal model for T2D, microbial dysbiosis is associated with increased resistance to chemotherapeutic compounds.

Gut Microbiome Modulates Response to Cancer Immunotherapy

With the advent of next-generation sequencing approaches, there has been a renaissance in the microbiome field. Microbial taxonomy and function can now be characterized relatively easily and rapidly-no longer mandating complex culturing approaches. With this renaissance, there is now a strong and growing appreciation for the role of the microbiome (referring to microbes and their genomes) in modulating many facets of physiology-including overall immunity. This is particularly true of the gut microbiome, and there is now an evolving body of the literature demonstrating a role for gut microbes in modulating responses to cancer treatment-particularly immunotherapy. Gut microbes can modulate immunity and anti-tumor responses via a number of different interactions, and these will be discussed herein. Additionally, data regarding the impact of gut microbes on cancer immunotherapy response will be discussed, as will strategies to manipulate the microbiome to enhance therapeutic responses. These efforts to date are not completely optimized; however, there is evidence of efficacy though much additional work is needed in this space. Nonetheless, it is clear that the microbiome plays a central role in health and disease, and strategies to manipulate it in cancer and overall precision health are being explored.

Role of the microbiome in occurrence, development and treatment of pancreatic cancer

Pancreatic cancer is one of the most lethal malignancies. Recent studies indicated that development of pancreatic cancer may be intimately connected with the microbiome. In this review, we discuss the mechanisms through which microbiomes affect the development of pancreatic cancer, including inflammation and immunomodulation. Potential therapeutic and diagnostic applications of microbiomes are also discussed. For example, microbiomes may serve as diagnostic markers for pancreatic cancer, and may also play an important role in determining the efficacies of treatments such as chemo- and immunotherapies. Future studies will provide additional insights into the various roles of microbiomes in pancreatic cancer.

Intestinal Microbiota: A Novel Target to Improve Anti-Tumor Treatment?

Recently, preclinical and clinical studies targeting several types of cancer strongly supported the key role of the gut microbiota in the modulation of host response to anti-tumoral therapies such as chemotherapy, immunotherapy, radiotherapy and even surgery. Intestinal microbiome has been shown to participate in the resistance to a wide range of anticancer treatments by direct interaction with the treatment or by indirectly stimulating host response through immunomodulation. Interestingly, these effects were described on colorectal cancer but also in other types of malignancies. In addition to their role in therapy efficacy, gut microbiota could also impact side effects induced by anticancer treatments. In the first part of this review, we summarized the role of the gut microbiome on the efficacy and side effects of various anticancer treatments and underlying mechanisms. In the second part, we described the new microbiota-targeting strategies, such as probiotics and prebiotics, antibiotics, fecal microbiota transplantation and physical activity, which could be effective adjuvant therapies developed in order to improve anticancer therapeutic efficiency.

The impact of tumor and gut microbiotas on cancer therapy: Beneficial or detrimental?

Cancer is a globally challenging health problem threatening mankind. Despite therapeutic advances in dealing with this malignancy, heterogeneous response and resistance to chemotherapeutic agents remain the hallmarks of cancer therapy. On the other hand, the involvement of the microbiota in affecting human health is well defined. An ever-growing body of evidence implicates the potential link between the microbiome and the efficacy of cancer therapies. Gut microbiota can modulate the metabolism of drugs in a number of ways. The presence of bacteria within the tumor environment can also impact the responses to cancer therapies; changing the chemical structure of chemotherapeutic drugs, affecting their activity, and local concentration. However, the underlying mechanisms by which gut and tumor microbial communities affect the response to cancer therapy are poorly understood and deciphering these mechanisms is of paramount importance. This review provides an overview of how gut and tumor microbiota might affect the efficacy of chemotherapy, radiotherapy, and immunotherapy and alleviate the adverse side effects of these therapies for the development of personalized and effective anticancer therapy.

Microbiome-Microbial Metabolome-Cancer Cell Interactions in Breast Cancer-Familiar, but Unexplored

Breast cancer is a leading cause of death among women worldwide. Dysbiosis, an aberrant composition of the microbiome, characterizes breast cancer. In this review we discuss the changes to the metabolism of breast cancer cells, as well as the composition of the breast and gut microbiome in breast cancer. The role of the breast microbiome in breast cancer is unresolved, nevertheless it seems that the gut microbiome does have a role in the pathology of the disease. The gut microbiome secretes bioactive metabolites (reactivated estrogens, short chain fatty acids, amino acid metabolites, or secondary bile acids) that modulate breast cancer. We highlight the bacterial species or taxonomical units that generate these metabolites, we show their mode of action, and discuss how the metabolites affect mitochondrial metabolism and other molecular events in breast cancer. These metabolites resemble human hormones, as they are produced in a "gland" (in this case, the microbiome) and they are subsequently transferred to distant sites of action through the circulation. These metabolites appear to be important constituents of the tumor microenvironment. Finally, we discuss how bacterial dysbiosis interferes with breast cancer treatment through interfering with chemotherapeutic drug metabolism and availability.

The Interplay between Immunity and Microbiota at Intestinal Immunological Niche: The Case of Cancer

The gut microbiota is central to the pathogenesis of several inflammatory and autoimmune diseases. While multiple mechanisms are involved, the immune system clearly plays a special role. Indeed, the breakdown of the physiological balance in gut microbial composition leads to dysbiosis, which is then able to enhance inflammation and to influence gene expression. At the same time, there is an intense cross-talk between the microbiota and the immunological niche in the intestinal mucosa. These interactions may pave the way to the development, growth and spreading of cancer, especially in the gastro-intestinal system. Here, we review the changes in microbiota composition, how they relate to the immunological imbalance, influencing the onset of different types of cancer and the impact of these mechanisms on the efficacy of traditional and upcoming cancer treatments.

Human Microbiota and Personalized Cancer Treatments: Role of Commensal Microbes in Treatment Outcomes for Cancer Patients

The human gut microbiota consists of about 3.8 × 10¹³ microorganisms that play an essential role in health, metabolism, and immunomodulation. These gut microbes alter therapeutic response and toxicity to cancer therapies including cytotoxic chemotherapy, radiation therapy, kinase inhibitors, and immunotherapy agents. The gut microbiota generates short-chain fatty acids that are significant regulators of histone post-translational modifications that fundamentally regulate gene expression, linking the microbiota to cellular metabolism and transcriptional regulation. The short-chain fatty acids not only act locally but can be taken up in the blood stream to inhibit the activity of histone deacetylases, regulate gene expression in distant organs as well as the effector function of CD8+ T cells. Cancer and the treatments for it negatively impact the microbiome often resulting in dysbiosis. This can diminish a patient's response to treatment as well as increase systemic toxicities from these therapies. In addition to the gut microbiota, microbes have been detected in tumors that can modulate chemotherapeutic drug response and can result in immune suppression. The gut microbiota and tumor-associated bacteria may be a significant contributor to the interindividual differences and heterogeneous responses to cancer therapies and drug tolerability and strategies that support and/or manipulate the microbiota to improve therapeutic outcome is an emerging area for personalized cancer treatment.

Hypoxia-Induced Resistance to Chemotherapy in Cancer

A major barrier to the successful management of cancer is the development of resistance to therapy. Chemotherapy resistance can either be an intrinsic property of malignant cells developed prior to therapy, or acquired following exposure to anti-cancer drugs. Given the impact of drug resistance to the overall poor survival of cancer patients, there is an urgent need to better understand the molecular pathways regulating this malignant phenotype. In this chapter we describe some of the molecular pathways that contribute to drug resistance in cancer, the role of a microenvironment deficient in oxygen (hypoxia) in malignant progression, and how hypoxia can be a significant factor in the development of drug resistance. We conclude by proposing potential therapeutic approaches that take advantage of a hypoxic microenvironment to chemosensitize therapy-resistant tumours.

Drug pharmacomicrobiomics and toxicomicrobiomics: from scattered reports to systematic studies of drug-microbiome interactions

INTRODUCTION

Pharmacomicrobiomics and toxicomicrobiomics study how variations within the human microbiome (the combination of human-associated microbial communities and their genomes) affect drug disposition, action, and toxicity. These emerging fields, interconnecting microbiology, bioinformatics, systems pharmacology, and toxicology, complement pharmacogenomics and toxicogenomics, expanding the scope of precision medicine. Areas covered: This article reviews some of the most recently reported pharmacomicrobiomic and toxicomicrobiomic interactions. Examples include the impact of the human gut microbiota on cardiovascular drugs, natural products, and chemotherapeutic agents, including immune checkpoint inhibitors. Although the gut microbiota has been the most extensively studied, some key drug-microbiome interactions involve vaginal, intratumoral, and environmental bacteria, and are briefly discussed here. Additionally, computational resources, moving the field from cataloging to predicting interactions, are introduced. Expert opinion: The rapid pace of discovery triggered by the Human Microbiome Project is moving pharmacomicrobiomic research from scattered observations to systematic studies focusing on screening microbiome variants against different drug classes. Better representation of all human populations will improve such studies by avoiding sampling bias, and the integration of multiomic studies with designed experiments will allow establishing causation. In the near future, pharmacomicrobiomic testing is expected to be a key step in screening novel drugs and designing precision therapeutics.

Microbial markers in colorectal cancer detection and/or prognosis

Colorectal cancer (CRC) is the second leading cause of cancer worldwide. CRC is still associated with a poor prognosis among patients with advanced disease. On the contrary, due to its slow progression from detectable precancerous lesions, the prognosis for patients with early stages of CRC is encouraging. While most robust methods are invasive and costly, actual patient-friendly screening methods for CRC suffer of lack of sensitivity and specificity. Therefore, the development of sensitive, non-invasive and cost-effective methods for CRC detection and prognosis are necessary for increasing the chances of a cure. Beyond its beneficial functions for the host, increasing evidence suggests that the intestinal microbiota is a key factor associated with carcinogenesis. Many clinical studies have reported a disruption in the gut microbiota balance and an alteration in the faecal metabolome of CRC patients, suggesting the potential use of a microbial-based test as a non-invasive diagnostic and/or prognostic tool for CRC screening. This review aims to discuss the microbial signatures associated with CRC known to date, including dysbiosis and faecal metabolome alterations, and the potential use of microbial variation markers for non-invasive early diagnosis and/or prognostic assessment of CRC and advanced adenomas. We will finally discuss the possible use of these markers as predicators for treatment response and their limitations.