Nucleoside-catabolizing enzymes in mycoplasma-infected tumor cell cultures compromise the cytostatic activity of the anticancer drug gemcitabine

The human microbiome: redefining cancer pathogenesis and therapy

The human microbiome has always been an important determinant of health and recently, its role has also been described in cancer. The altered microbiome could aid cancer progression, modulate chemoresistance and significantly alter drug efficacy. The broad implications of microbes in cancer have prompted researchers to investigate the microbe-cancer axis and identify whether modifying the microbiome could sensitize cancer cells for therapy and improve the survival outcome of cancer patients. The preclinical data has shown that enhancing the number of specific microbial species could restore the patients' response to cancer drugs and the microbial biomarkers may play a vital role in cancer diagnostics. The elucidation of detailed interactions of the human microbiota with cancer would not only help identify the novel drug targets but would also enhance the efficacy of existing drugs. The field exploring the emerging roles of microbiome in cancer is at a nascent stage and an in-depth scientific perspective on this topic would make it more accessible to a wider audience. In this review, we discuss the scientific evidence connecting the human microbiome to the origin and progression of cancer. We also discuss the potential mechanisms by which microbiota affects initiation of cancer, metastasis and chemoresistance. We highlight the significance of the microbiome in therapeutic outcome and evaluate the potential of microbe-based cancer therapy.

Nanoimmunotherapy: the smart trooper for cancer therapy

Immunotherapy has gathered significant attention and is now a widely used cancer treatment that uses the body's immune system to fight cancer. Despite initial successes, its broader clinical application is hindered by limitations such as heterogeneity in patient response and challenges associated with the tumor immune microenvironment. Recent advancements in nanotechnology have offered innovative solutions to these barriers, providing significant enhancements to cancer immunotherapy. Nanotechnology-based approaches exhibit multifaceted mechanisms, including effective anti-tumor immune responses during tumorigenesis and overcoming immune suppression mechanisms to improve immune defense capacity. Nanomedicines, including nanoparticle-based vaccines, liposomes, immune modulators, and gene delivery systems, have demonstrated the ability to activate immune responses, modulate tumor microenvironments, and target specific immune cells. Success metrics in preclinical and early clinical studies, such as improved survival rates, enhanced tumor regression, and elevated immune activation indices, highlight the promise of these technologies. Despite these achievements, several challenges remain, including scaling up manufacturing, addressing off-target effects, and navigating regulatory complexities. The review emphasizes the need for interdisciplinary approaches to address these barriers, ensuring broader clinical adoption. It also provides insights into interdisciplinary approaches, advancements, and the transformative potential of nano-immunotherapy and promising results in checkpoint inhibitor delivery, nanoparticle-mediated photothermal therapy, immunomodulation as well as inhibition by nanoparticles and cancer vaccines.

Antibiotic treatment and survival in patients with resected, early-stage pancreatic ductal adenocarcinoma receiving chemotherapy

BACKGROUND

Pancreatic ductal adenocarcinoma is a clinically challenging malignancy largely because of its chemoresistance. Bacteria within the pancreatic ductal adenocarcinoma microbiome may mediate chemoresistance, suggesting that alteration of the microbiome with antibiotics could improve chemotherapy response.

METHODS

We utilized the Surveillance, Epidemiology, and End Results Program-Medicare database to select patients with resected, early-stage pancreatic ductal adenocarcinoma diagnosed between 2007 and 2017. The primary outcome of this study was overall survival. Receipt of antibiotic treatment within 1 month after adjuvant chemotherapy initiation was determined from Medicare claims data. Propensity scores were used to match patients who received antibiotics with patients who did not receive antibiotics. The Kaplan-Meier method was used to calculate 5-year overall survival rates, and Cox regression analysis was used to assess the association between receiving antibiotics and overall survival. All hypotheses were 2 sided.

RESULTS

Of the 712 patients with resected, early-stage pancreatic ductal adenocarcinoma, 629 (88.3%) were treated with adjuvant gemcitabine and 177 (24.9%) received antibiotics in the 1 month following chemotherapy initiation. The mean (SD) age at diagnosis was 73.7 (5.1) years, and patients were mostly women, White, and from metropolitan areas in the northeastern or western United States. A total of 143 propensity score-matched pairs were evaluated. Among patients treated with gemcitabine, antibiotic treatment was associated with a 37% improvement in overall survival and a 30% improvement in cancer-specific survival.

CONCLUSIONS

Antibiotic treatment in the 1 month following adjuvant gemcitabine initiation was associated with improved survival. These findings provide additional support for the hypothesis that antibiotic treatment may alter the pancreatic microbiome in a manner that reduces chemoresistance, potentially improving pancreatic ductal adenocarcinoma outcomes.

Gut microbiota interact with breast cancer therapeutics to modulate efficacy

The gut microbiome, or the community of microorganisms residing in the gastrointestinal tract, has emerged as an important factor in breast cancer etiology and treatment. Specifically, the impact of gut bacterial populations on breast cancer therapeutic outcomes is an emerging area of research. The microbiota's role in modifying the pharmacokinetics of chemotherapy and endocrine-targeting therapies can alter drug efficacy and toxicity profiles. In addition, the gut microbiome's capacity to regulate systemic inflammation and immune responses may influence the effectiveness of both conventional and immunotherapeutic strategies for the treatment of breast cancer. Overall, while the bidirectional interactions between the gut microbiome and breast cancer therapies are still being studied, its impact is increasingly recognized. Future research may provide more definitive insights and help develop personalized therapeutic strategies to harness the microbiome to improve breast cancer treatment outcomes.

Gut-X axis

Recent advances in understanding the modulatory functions of gut and gut microbiota on human diseases facilitated our focused attention on the contribution of the gut to the pathophysiological alterations of many extraintestinal organs, including the liver, heart, brain, lungs, kidneys, bone, skin, reproductive, and endocrine systems. In this review, we applied the "gut-X axis" concept to describe the linkages between the gut and other organs and discussed the latest findings related to the "gut-X axis," including the underlying modulatory mechanisms and potential clinical intervention strategies.

Unveiling the Interplay Between the Human Microbiome and Gastric Cancer: A Review of the Complex Relationships and Therapeutic Avenues

The human microbiota plays a crucial role in maintaining overall health and well-being. The gut microbiota has been implicated in developing and progressing various diseases, including cancer. This review highlights the related mechanisms and the compositions that influence cancer pathogenesis with a highlight on gastric cancer. We provide a comprehensive overview of the mechanisms by which the microbiome influences cancer development, progression, and response to treatment, with a focus on identifying potential biomarkers for early detection, prevention strategies, and novel therapeutic interventions that leverage microbiome modulation. This comprehensive review can guide future research and clinical practices in understanding and harnessing the microbiome to optimize gastric cancer therapies.

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.

Targeting the gut and tumor microbiome in cancer treatment resistance

Therapy resistance represents a significant challenge in oncology, occurring in various therapeutic approaches. Recently, animal models and an increasing set of clinical trials highlight the crucial impact of the gut and tumor microbiome on treatment response. The intestinal microbiome contributes to cancer initiation, progression, and formation of distant metastasis. In addition, tumor-associated microbiota is considered a critical player in influencing tumor microenvironments and regulating local immune processes. Intriguingly, numerous studies have successfully identified pathogens within the gut and tumor microbiome that might be linked to a poor response to different therapeutic modalities. The unfavorable microbial composition with the presence of specific microbes participates in cancer resistance and progression via several mechanisms, including upregulation of oncogenic pathways, macrophage polarization reprogramming, metabolism of chemotherapeutic compounds, autophagy pathway modulation, enhanced DNA damage repair, inactivation of a proapoptotic cascade, and bacterial secretion of extracellular vesicles, promoting the processes in the metastatic cascade. Targeted elimination of specific intratumoral bacteria appears to enhance treatment response. However, broad-spectrum antibiotic pretreatment is mostly connected to reduced efficacy due to gut dysbiosis and lower diversity. Mounting evidence supports the potential of microbiota modulation by probiotics and fecal microbiota transplantation to improve intestinal dysbiosis and increase microbial diversity, leading to enhanced treatment efficacy while mitigating adverse effects. In this context, further research concerning the identification of clinically relevant microbiome signatures followed by microbiota-targeted strategies presents a promising approach to overcoming immunotherapy and chemotherapy resistance in refractory patients, improving their outcomes.

Current status and prospect of gut and oral microbiome in pancreatic cancer: Clinical and translational perspectives

Pancreatic cancer is a highly lethal malignancy, and its diagnosis and treatment continue to pose significant challenges. Despite advancements in surgical and comprehensive treatment methods, the five-year survival rate remains below 12 %. With the rapid development of microbiome science, the gut and oral microbiota, which are readily accessible and can be sampled non-invasively, have emerged as a novel area of interest in pancreatic cancer research. Dysbiosis in these microbial communities can induce persistent inflammatory responses and affect the host's immune system, promoting cancer development and impacting the efficacy of treatments like chemotherapy and immunotherapy. This review provides an up-to-date overview of the roles of both gut and oral microbiota in the onset, progression, diagnosis, and treatment of pancreatic cancer. It analyzes the potential of utilizing these microbiomes as biomarkers and therapeutic targets from a clinical application perspective. Furthermore, it discusses future research directions aimed at harnessing these insights to advance the diagnosis and treatment strategies for pancreatic cancer. By focusing on the microbiome's role in clinical and translational medicine, this review offers insights into improving pancreatic cancer diagnosis and treatment outcomes.

The role of gut microbiota and metabolites in cancer chemotherapy

BACKGROUND

The microbiota inhabits the epithelial surfaces of hosts, which influences physiological functions from helping digest food and acquiring nutrition to regulate metabolism and shaping host immunity. With the deep insight into the microbiota, an increasing amount of research reveals that it is also involved in the initiation and progression of cancer. Intriguingly, gut microbiota can mediate the biotransformation of drugs, thereby altering their bioavailability, bioactivity, or toxicity.

AIM OF REVIEW

The review aims to elaborate on the role of gut microbiota and microbial metabolites in the efficacy and adverse effects of chemotherapeutics. Furthermore, we discuss the clinical potential of various ways to harness gut microbiota for cancer chemotherapy.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Recent evidence shows that gut microbiota modulates the efficacy and toxicity of chemotherapy agents, leading to diverse host responses to chemotherapy. Thereinto, targeting the microbiota to improve efficacy and diminish the toxicity of chemotherapeutic drugs may be a promising strategy in tumor treatment.

Crosstalk between gut microbiota and host immune system and its response to traumatic injury

Millions of microorganisms make up the complex microbial ecosystem found in the human gut. The immune system's interaction with the gut microbiota is essential for preventing inflammation and maintaining intestinal homeostasis. Numerous metabolic products that can cross-talk between immune cells and the gut epithelium are metabolized by the gut microbiota. Traumatic injury elicits a great and multifaceted immune response in the minutes after the initial offense, containing simultaneous pro- and anti-inflammatory responses. The development of innovative therapies that improve patient outcomes depends on the gut microbiota and immunological responses to trauma. The altered makeup of gut microbes, or gut dysbiosis, can also dysregulate immunological responses, resulting in inflammation. Major human diseases may become more common as a result of chronic dysbiosis and the translocation of bacteria and the products of their metabolism beyond the mucosal barrier. In this review, we briefly summarize the interactions between the gut microbiota and the immune system and human disease and their therapeutic probiotic formulations. We also discuss the immune response to traumatic injury.

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.

Influence of Gut Microbiota-Mediated Immune Regulation on Response to Chemotherapy

The involvement of the gut microbiota in anti-cancer treatment has gained increasing attention. Alterations to the structure and function of the gut bacteria are important factors in the development of cancer as well as the efficacy of chemotherapy. Recent studies have confirmed that the gut microbiota and related metabolites influence the pharmacological activity of chemotherapeutic agents through interactions with the immune system. This review aims to summarize the current knowledge of how malignant tumor and chemotherapy affect the gut microbiota, how the gut microbiota regulates host immune response, and how interactions between the gut microbiota and host immune response influence the efficacy of chemotherapy. Recent advances in strategies for increasing the efficiency of chemotherapy based on the gut microbiota are also described. Deciphering the complex homeostasis maintained by the gut microbiota and host immunity provides a solid scientific basis for bacterial intervention in chemotherapy.

Identification of intratumor bacteria-associated prognostic risk score in adrenocortical carcinoma

A landmark study by Poore et al. showed intratumor bacteria (ITBs) playing a critical role in most cancers by reproduction of The Cancer Genome Atlas (TCGA) transcriptome data. A recent study by Salzberg et al. argued that ITBs, being overstated as a methodology by Poore et al., were problematic. We previously reported that ITBs were prognostic in adrenocortical carcinoma (ACC), a highly aggressive rare disease using data by Poore et al., and here, we aimed to answer whether ITBs truly existed and were prognostic in ACC. ACC samples from our institutes underwent 16S rRNA sequencing [adrenocortical carcinoma blocks from Huashan Hospital and China Medical University (HS) cohort]. The ITB profile was compared to TCGA data processed by Poore et al. (TCGA-P) and TCGA data processed by Salzberg et al. (TCGA-S), respectively. The primary outcome was overall survival (OS). A total of 26 ACC cases (HS cohort) and 10 paraffin controls were sequenced. The TCGA cohort encompassed 77 cases. Two and four amid the top 10 abundant genera in HS cohort were not detected in TCGA-P and TCGA-S, respectively. Neither was alpha or beta diversity associated with survival nor could ACC be subtyped by ITB signature in the HS cohort. Notably, a five-genera ITB risk score (Corynebacterium, Mycoplasma, Achromobacter, Anaerococcus, and Streptococcus) for OS trained in the HS cohort was validated in both TCGA-P and TCGA-S cohorts and was independently prognostic. Whereas ITB signature on the whole may not be associated with ACC subtypes, certain ITB features are associated with prognosis, and a risk score could be generated and validated externally.

IMPORTANCE

In this report, we looked at the role of ITBs in ACC in patients with different race and sequencing platforms. We found a five-genera ITB risk score consistently predicted overall survival in all cohorts. We conclude that certain ITB features are universally pathogenic to ACC.

Emerging clinical relevance of microbiome in cancer: promising biomarkers and therapeutic targets

The profound influence of microbiota in cancer initiation and progression has been under the spotlight for years, leading to numerous researches on cancer microbiome entering clinical evaluation. As promising biomarkers and therapeutic targets, the critical involvement of microbiota in cancer clinical practice has been increasingly appreciated. Here, recent progress in this field is reviewed. We describe the potential of tumor-associated microbiota as effective diagnostic and prognostic biomarkers, respectively. In addition, we highlight the relationship between microbiota and the therapeutic efficacy, toxicity, or side effects of commonly utilized treatments for cancer, including chemotherapy, radiotherapy, and immunotherapy. Given that microbial factors influence the cancer treatment outcome, we further summarize some dominating microbial interventions and discuss the hidden risks of these strategies. This review aims to provide an overview of the applications and advancements of microbes in cancer clinical relevance.

Bacterial DnaK reduces the activity of anti-cancer drugs cisplatin and 5FU

BACKGROUND

Chemotherapy is a primary treatment for cancer, but its efficacy is often limited by cancer-associated bacteria (CAB) that impair tumor suppressor functions. Our previous research found that Mycoplasma fermentans DnaK, a chaperone protein, impairs p53 activities, which are essential for most anti-cancer chemotherapeutic responses.

METHODS

To investigate the role of DnaK in chemotherapy, we treated cancer cell lines with M. fermentans DnaK and then with commonly used p53-dependent anti-cancer drugs (cisplatin and 5FU). We evaluated the cells' survival in the presence or absence of a DnaK-binding peptide (ARV-1502). We also validated our findings using primary tumor cells from a novel DnaK knock-in mouse model. To provide a broader context for the clinical significance of these findings, we investigated human primary cancer sequencing datasets from The Cancer Genome Atlas (TCGA). We identified F. nucleatum as a CAB carrying DnaK with an amino acid composition highly similar to M. fermentans DnaK. Therefore, we investigated the effect of F. nucleatum DnaK on the anti-cancer activity of cisplatin and 5FU.

RESULTS

Our results show that both M. fermentans and F. nucleatum DnaKs reduce the effectiveness of cisplatin and 5FU. However, the use of ARV-1502 effectively restored the drugs' anti-cancer efficacy.

CONCLUSIONS

Our findings offer a practical framework for designing and implementing novel personalized anti-cancer strategies by targeting specific bacterial DnaKs in patients with poor response to chemotherapy, underscoring the potential for microbiome-based personalized cancer therapies.

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.

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.

Intratumor Mycoplasma promotes the initiation and progression of hepatocellular carcinoma

The carcinogenesis and progression of hepatocellular carcinoma (HCC) are closely related to viral infection and intestinal bacteria. However, little is known about bacteria within the HCC tumor microenvironment. Here, we showed that intratumoral Mycoplasma hyorhinis (M. hyorhinis) promoted the initiation and progression of HCC by enhancing nuclear ploidy. We quantified M. hyorhinis in clinical tissue specimens of HCC and observed that patients with high M. hyorhinis load had poor prognosis. We found that gastrointestinal M. hyorhinis can retrogradely infect the liver through the oral-duodenal-hepatopancreatic ampulla route. We further found that the increases in mononuclear polyploidy and cancer stemness resulted from mitochondrial fission caused by intracellular M. hyorhinis. Mechanistically, M. hyorhinis infection promoted the decay of mitochondrial fusion protein (MFN) 1 mRNA in an m6A-dependent manner. Our findings indicated that M. hyorhinis infection promoted pathological polyploidization and suggested that Mycoplasma clearance with antibiotics or regulating mitochondrial dynamics might have the potential for HCC therapy.

Microbiota in cancer: molecular mechanisms and therapeutic interventions

The diverse bacterial populations within the symbiotic microbiota play a pivotal role in both health and disease. Microbiota modulates critical aspects of tumor biology including cell proliferation, invasion, and metastasis. This regulation occurs through mechanisms like enhancing genomic damage, hindering gene repair, activating aberrant cell signaling pathways, influencing tumor cell metabolism, promoting revascularization, and remodeling the tumor immune microenvironment. These microbiota-mediated effects significantly impact overall survival and the recurrence of tumors after surgery by affecting the efficacy of chemoradiotherapy. Moreover, leveraging the microbiota for the development of biovectors, probiotics, prebiotics, and synbiotics, in addition to utilizing antibiotics, dietary adjustments, defensins, oncolytic virotherapy, and fecal microbiota transplantation, offers promising alternatives for cancer treatment. Nonetheless, due to the extensive and diverse nature of the microbiota, along with tumor heterogeneity, the molecular mechanisms underlying the role of microbiota in cancer remain a subject of intense debate. In this context, we refocus on various cancers, delving into the molecular signaling pathways associated with the microbiota and its derivatives, the reshaping of the tumor microenvironmental matrix, and the impact on tolerance to tumor treatments such as chemotherapy and radiotherapy. This exploration aims to shed light on novel perspectives and potential applications in the field.

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.

The potential role of the microbiota in prostate cancer pathogenesis and treatment

The human body hosts a complex and dynamic population of trillions of microorganisms - the microbiota - which influences the body in homeostasis and disease, including cancer. Several epidemiological studies have associated specific urinary and gut microbial species with increased risk of prostate cancer; however, causal mechanistic data remain elusive. Studies have associated bacterial generation of genotoxins with the occurrence of TMPRSS2-ERG gene fusions, a common, early oncogenic event during prostate carcinogenesis. A subsequent study demonstrated the role of the gut microbiota in prostate cancer endocrine resistance, which occurs, at least partially, through the generation of androgenic steroids fuelling oncogenic signalling via the androgen receptor. These studies present mechanistic evidence of how the host microbiota might be implicated in prostate carcinogenesis and tumour progression. Importantly, these findings also reveal potential avenues for the detection and treatment of prostate cancer through the profiling and modulation of the host microbiota. The latter could involve approaches such as the use of faecal microbiota transplantation, prebiotics, probiotics, postbiotics or antibiotics, which can be used independently or combined with existing treatments to reverse therapeutic resistance and improve clinical outcomes in patients with prostate cancer.

Bibliometric analysis of global research trends between gut microbiota and pancreatic cancer: from 2004 to 2023

BACKGROUND

Pancreatic cancer (PC) is one of the most lethal malignancies of the digestive system and is expected to be the second leading cause of cancer-related death in the United States by 2030. A growing body of evidence suggests that the gut microbiota (GM) is intimately involved in the clinical diagnosis, oncogenic mechanism and treatment of PC. However, no bibliometric analysis of PC and GM has been reported.

METHODS

The literature on PC and GM was retrieved from the Web of Science Core Collection (WoSCC) database for the period from January 1, 2004 to April 25, 2023. Microsoft Excel 2021, CiteSpace, VOSviewer, Scimago Graphica, Graphpad Prism, Origin, the R package "bibliometrics" and the bibliometric online analysis program were used to visualize the publishing trends and hot spots in this field.

RESULTS

A total of 1,449 articles were included, including 918 articles and 531 reviews. Publishing had grown rapidly since 2017, with the 2023 expected to publish 268 articles. Unsurprisingly, the United States ranked highest in terms of number of literatures, H index and average citations. The University of California System was the most active institution, but Harvard University tended to be cited the most on average. The three most influential researchers were Robert M. Hoffman, Zhao Minglei, and Zhang Yong. Cancers had published the most papers, while Nature was the most cited journal. Keyword analysis and theme analysis indicated that "tumor microenvironment," "gemcitabine-resistance," "ductal adenocarcinoma," "gut microbiota" and "diagnosis" will be the hotspots and frontiers of research in the future.

CONCLUSION

In summary, the field is receiving increasing attention. We found that future hotspots of PC/GM research may focus on the mechanism of oncogenesis, flora combination therapy and the exploitation of new predictive biomarkers, which provides effective suggestions and new insights for scholars.

The correlation between gut and intra-tumor microbiota and PDAC: Etiology, diagnostics and therapeutics

Pancreatic ductal adenocarcinoma (PDAC) is one of the lethal cancers in the world and its 5-year survival rate is <10%. Due to the unique TME and dense tissue structure, its curative efficacy is far from satisfactory，the immunotherapy is even more invalid. According to the recent studies, the gut and tumor microbiota have been proved to play a key role in the development, progression and prognosis of PDAC. Based on the differences of microbiome composition observed in PDAC patients and normal pancreas, many researches have been made focusing on the latent communication between gut and intra-tumor microbiota and PDAC. In this review, we will demonstrate the potential mechanism of the oncogenic effects of GM and IM and their crucial effects on modulating the TME. Besides, we focus on their interaction with chemotherapeutic and immunotherapeutic drugs and inducing the drug resistance, thus enlightening the promising role to be used to monitor the occurrence of PDAC, accurately modulate the immune environment to promote the therapeutic efficacy and predict the prognosis.

Intestinal Flora in Chemotherapy Resistance of Biliary Pancreatic Cancer

Biliary pancreatic malignancy has an occultic onset, a high degree of malignancy, and a poor prognosis. Most clinical patients miss the opportunity for surgical resection of the tumor. Systemic chemotherapy is still one of the important methods for the treatment of biliary pancreatic malignancies. Many chemotherapy regimens are available, but their efficacy is not satisfactory, and the occurrence of chemotherapy resistance is a major reason leading to poor prognosis. With the advancement of studies on intestinal flora, it has been found that intestinal flora is correlated with and plays an important role in chemotherapy resistance. The application of probiotics and other ways to regulate intestinal flora can improve this problem. This paper aims to review and analyze the research progress of intestinal flora in the chemotherapy resistance of biliary pancreatic malignancies to provide new ideas for treatment.

Bile Acids and Microbiota Interplay in Pancreatic Cancer

Evidence suggests the involvement of the microbiota, including oral, intra-tumoral and gut, in pancreatic cancer progression and response to therapy. The gut microbiota modulates the bile acid pool and is associated with maintaining host physiology. Studies have shown that the bile acid/gut microbiota axis is dysregulated in pancreatic cancer. Bile acid receptor expression and bile acid levels are dysregulated in pancreatic cancer as well. Studies have also shown that bile acids can cause pancreatic cell injury and facilitate cancer cell proliferation. The microbiota and its metabolites, including bile acids, are also altered in other conditions considered risk factors for pancreatic cancer development and can alter responses to chemotherapeutic treatments, thus affecting patient outcomes. Altogether, these findings suggest that the gut microbial and/or bile acid profiles could also serve as biomarkers for pancreatic cancer detection. This review will discuss the current knowledge on the interaction between gut microbiota interaction and bile acid metabolism in pancreatic cancer.

State-of-the-Art and Upcoming Innovations in Pancreatic Cancer Care: A Step Forward to Precision Medicine

Pancreatic cancer remains a social and medical burden despite the tremendous advances that medicine has made in the last two decades. The incidence of pancreatic cancer is increasing, and it continues to be associated with high mortality and morbidity rates. The difficulty of early diagnosis (the lack of specific symptoms and biomarkers at early stages), the aggressiveness of the disease, and its resistance to systemic therapies are the main factors for the poor prognosis of pancreatic cancer. The only curative treatment for pancreatic cancer is surgery, but the vast majority of patients with pancreatic cancer have advanced disease at the time of diagnosis. Pancreatic surgery is among the most challenging surgical procedures, but recent improvements in surgical techniques, careful patient selection, and the availability of minimally invasive techniques (e.g., robotic surgery) have dramatically reduced the morbidity and mortality associated with pancreatic surgery. Patients who are not candidates for surgery may benefit from locoregional and systemic therapy. In some cases (e.g., patients for whom marginal resection is feasible), systemic therapy may be considered a bridge to surgery to allow downstaging of the cancer; in other cases (e.g., metastatic disease), systemic therapy is considered the standard approach with the goal of prolonging patient survival. The complexity of patients with pancreatic cancer requires a personalized and multidisciplinary approach to choose the best treatment for each clinical situation. The aim of this article is to provide a literature review of the available treatments for the different stages of pancreatic cancer.

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.

The Role of Microbiota in Pancreatic Cancer

Pancreatic cancer (PC) has an unfavorable prognosis with few effective therapeutic options. This has led researchers to investigate the possible links between microbiota and PC. A disrupted gut microbiome can lead to chronic inflammation, which is involved in the pathogenesis of PC. In addition, some bacterial strains can produce carcinogens that promote the growth of cancer cells. Research has also focused on pancreatic and oral microbiota. Changes in these microbiota can contribute to the development and progression of PC. Furthermore, patients with periodontal disease have an increased risk of developing PC. The potential use of microbiota as a prognostic marker or to predict patients' responses to chemotherapy or immunotherapy is also being explored. Overall, the role of microbiota-including the gut, pancreatic, and oral microbiota-in PC is an active research area. Understanding these associations could lead to new diagnostic and therapeutic targets for this deadly disease.

The Interplay between Gut Microbiota and Oral Medications and Its Impact on Advancing Precision Medicine

Trillions of diverse microbes reside in the gut and are deeply interwoven with the human physiological process, from food digestion, immune system maturation, and fighting invading pathogens, to drug metabolism. Microbial drug metabolism has a profound impact on drug absorption, bioavailability, stability, efficacy, and toxicity. However, our knowledge of specific gut microbial strains, and their genes that encode enzymes involved in the metabolism, is limited. The microbiome encodes over 3 million unique genes contributing to a huge enzymatic capacity, vastly expanding the traditional drug metabolic reactions that occur in the liver, manipulating their pharmacological effect, and, ultimately, leading to variation in drug response. For example, the microbial deactivation of anticancer drugs such as gemcitabine can lead to resistance to chemotherapeutics or the crucial role of microbes in modulating the efficacy of the anticancer drug, cyclophosphamide. On the other hand, recent findings show that many drugs can shape the composition, function, and gene expression of the gut microbial community, making it harder to predict the outcome of drug-microbiota interactions. In this review, we discuss the recent understanding of the multidirectional interaction between the host, oral medications, and gut microbiota, using traditional and machine-learning approaches. We analyze gaps, challenges, and future promises of personalized medicine that consider gut microbes as a crucial player in drug metabolism. This consideration will enable the development of personalized therapeutic regimes with an improved outcome, ultimately leading to precision medicine.

A Review of Gut Microbiota-Derived Metabolites in Tumor Progression and Cancer Therapy

Gut microbiota-derived metabolites are key hubs connecting the gut microbiome and cancer progression, primarily by remodeling the tumor microenvironment and regulating key signaling pathways in cancer cells and multiple immune cells. The use of microbial metabolites in radiotherapy and chemotherapy mitigates the severe side effects from treatment and improves the efficacy of treatment. Immunotherapy combined with microbial metabolites effectively activates the immune system to kill tumors and overcomes drug resistance. Consequently, various novel strategies have been developed to modulate microbial metabolites. Manipulation of genes involved in microbial metabolism using synthetic biology approaches directly affects levels of microbial metabolites, while fecal microbial transplantation and phage strategies affect levels of microbial metabolites by altering the composition of the microbiome. However, some microbial metabolites harbor paradoxical functions depending on the context (e.g., type of cancer). Furthermore, the metabolic effects of microorganisms on certain anticancer drugs such as irinotecan and gemcitabine, render the drugs ineffective or exacerbate their adverse effects. Therefore, a personalized and comprehensive consideration of the patient's condition is required when employing microbial metabolites to treat cancer. The purpose of this review is to summarize the correlation between gut microbiota-derived metabolites and cancer, and to provide fresh ideas for future scientific research.

Prediction of potential drug-microbe associations based on matrix factorization and a three-layer heterogeneous network

Microbes in the human body are closely linked to many complex human diseases and are emerging as new drug targets. These microbes play a crucial role in drug development and disease treatment. Traditional methods of biological experiments are not only time-consuming but also costly. Using computational methods to predict microbe-drug associations can effectively complement biological experiments. In this experiment, we constructed heterogeneity networks for drugs, microbes, and diseases using multiple biomedical data sources. Then, we developed a model with matrix factorization and a three-layer heterogeneous network (MFTLHNMDA) to predict potential drug-microbe associations. The probability of microbe-drug association was obtained by a global network-based update algorithm. Finally, the performance of MFTLHNMDA was evaluated in the framework of leave-one-out cross-validation (LOOCV) and 5-fold cross-validation (5-fold CV). The results showed that our model performed better than six state-of-the-art methods that had AUC of 0.9396 and 0.9385 + /- 0.0000, respectively. This case study further confirms the effectiveness of MFTLHNMDA in identifying potential drug-microbe associations and new drug-microbe associations.

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.

Monitoring and Modulating Diet and Gut Microbes to Enhance Response and Reduce Toxicity to Cancer Treatment

The gut microbiome comprises a diverse array of microbial species that have been shown to dynamically modulate host immunity both locally and systemically, as well as contribute to tumorigenesis. In this review, we discuss the scientific evidence on the role that gut microbes and diet play in response and toxicity to cancer treatment. We highlight studies across multiple cancer cohorts that have shown an association between particular gut microbiome signatures and an improved response to immune checkpoint blockade, chemotherapy, and adoptive cell therapies, as well as the role of particular microbes in driving treatment-related toxicity and how the microbiome can be modulated through strategies, such as fecal transplant. We also summarize the current literature that implicate high fiber and ketogenic diets in improved response rates to immunotherapy and chemotherapy, respectively. Finally, we discuss the relevance of these findings in the context of patient care, advocate for a holistic approach to cancer treatment, and comment on the next frontier of targeted gut and tumor microbiome modulation through novel therapeutics, dietary intervention, and precision-medicine approaches.

Pancreatic Cancer Resistance to Treatment: The Role of Microbiota

Pancreatic cancer (PC) is an aggressive malignancy and the fourth leading cause of cancer death in the United States and Europe. It is estimated that PC will be the second leading cause of cancer death by 2030. In addition to late diagnosis, treatment resistance is a major cause of shortened survival in pancreatic cancer. In this context, there is growing evidence that microbes play a regulatory role, particularly in therapy resistance and in creating a microenvironment in the tumor, that favors cancer progression. The presence of certain bacteria belonging to the gamma-proteobacteria or mycoplasmas appears to be associated with both pharmacokinetic and pharmacodynamic changes. Recent evidence suggests that the microbiota may also play a role in resistance mechanisms to immunotherapy and radiotherapy. However, the interactions between microbiota and therapy are bilateral and modulate therapy tolerance. Future perspectives are increasingly focused on elucidating the role of the microbiota in tumorigenesis and processes of therapy resistance, and a better understanding of these mechanisms may provide important opportunities to improve survival in these patients.

Microbiota in the Natural History of Pancreatic Cancer: From Predisposition to Therapy

Early microbiome insights came from gut microbes and their role among intestinal and extraintestinal disease. The latest evidence suggests that the microbiota is a true organ, capable of several interactions throughout the digestive system, attracting specific interest in the biliopancreatic district. Despite advances in diagnostics over the last few decades and improvements in the management of this disease, pancreatic cancer is still a common cause of cancer death. Microbiota can influence the development of precancerous disease predisposing to pancreatic cancer (PC). At the same time, neoplastic tissue shows specific characteristics in terms of diversity and phenotype, determining the short- and long-term prognosis. Considering the above information, a role for microbiota has also been hypothesized in the different phases of the PC approach, providing future revolutionary therapeutic insights. Microbiota-modulating therapies could open new issues in the therapeutic landscape. The aim of this narrative review is to assess the most updated evidence on microbiome in all the steps regarding pancreatic adenocarcinoma, from early development to response to antineoplastic therapy and long-term prognosis.

Tumor microbiome - an integral part of the tumor microenvironment

The tumor microenvironment (TME) plays a significant role in tumor progression and cancer cell survival. Besides malignant cells and non-malignant components, including immune cells, elements of the extracellular matrix, stromal cells, and endothelial cells, the tumor microbiome is considered to be an integral part of the TME. Mounting evidence from preclinical and clinical studies evaluated the presence of tumor type-specific intratumoral bacteria. Differences in microbiome composition between cancerous tissues and benign controls suggest the importance of the microbiome-based approach. Complex host-microbiota crosstalk within the TME affects tumor cell biology via the regulation of oncogenic pathways, immune response modulation, and interaction with microbiota-derived metabolites. Significantly, the involvement of tumor-associated microbiota in cancer drug metabolism highlights the therapeutic implications. This review aims to summarize current knowledge about the emerging role of tumor microbiome in various types of solid malignancies. The clinical utility of tumor microbiome in cancer progression and treatment is also discussed. Moreover, we provide an overview of clinical trials evaluating the role of tumor microbiome in cancer patients. The research focusing on the communication between the gut and tumor microbiomes may bring new opportunities for targeting the microbiome to increase the efficacy of cancer treatment and improve patient outcomes.

Insights into the role of gut and intratumor microbiota in pancreatic ductal adenocarcinoma as new key players in preventive, diagnostic and therapeutic perspective

Microbiota consists of a dynamic organization of bacteria, viruses, archaea, and fungal species involved in a number of vital functions spanning from the digestion of carbohydrates, vitamin synthesis, involvement in immune system to drug metabolism. More than 95 % of microbiota resides within the gut and it is essential for maintaining gut homeostasis. Dysregulation of gut microbiota contributes to the onset of several non-communicable diseases including cancer. Among the latter, pancreatic cancer is catching the attention of scientists around the globe being one of the most aggressive and resistant to therapies positioning the pancreatic cancer as one of the leading causes of death from cancer worldwide. In recent years, several studies have shown that the gut and tumor microbiota play a key role in the development, progression and prognosis of PDAC, mainly due to microbial ability to modulate host immune system and metabolize drugs. This review will focus on the new insights into the role of the microbiota as a new key player in pancreatic cancer PDAC development and prognosis by enlightening the microbial potential to interact with chemo/immunotherapeutic drugs and to modulate tumor microenvironment, thus impacting on cancer therapy success with the aim to pave the way to new integrative and interventional diagnostics or therapeutics approaches to prevent, diagnose and treat pancreatic cancer.

Microbiota and prostate cancer

Prostate cancer remains the most frequently diagnosed non-skin malignancy in male patients, still representing one of the main causes of cancer-related death worldwide. Evidence is mounting that suggests the putative role of microbiota in the carcinogenesis as well as in modulating the efficacy and activity of anticancer treatments (e.g., chemotherapy, immune checkpoint inhibitors, targeted therapies) in a large number of hematological and solid tumors. However, few data are available regarding the interactions between prostate cancer and microbiome so far, in particular in terms of the impact of microbiota on disease development, pathogenesis, and response to medical treatments in this genitourinary malignancy. Herein, we provide an overview of current knowledge, novel insights and emerging therapeutic approaches related to gastrointestinal and genitourinary microbiome in prostate cancer patients, especially focusing on available evidence and published trials on this topic.

Effects of microbiota on anticancer drugs: Current knowledge and potential applications

Over the last decade, mounting evidence has revealed the key roles of gut microbiota in modulating the efficacy and toxicity of anticancer drugs, via mechanisms such as immunomodulation and microbial enzymatic degradation. As such, human microbiota presents as an exciting prospect for developing biomarkers for predicting treatment outcomes and interventional approaches for improving therapeutic effects. In this review, we analyze the current knowledge of the interplays among gut microorganisms, host responses and anticancer therapies (including cytotoxic chemotherapy and targeted therapy), with an emphasis on the immunomodulation function of microbiota which facilitates the efficacy of immune checkpoint inhibitors. Moreover, we propose several microbiota-modulating strategies including fecal microbiota transplantation and probiotics, which can be pursued to optimize the use and development of anticancer treatments. We anticipate that future clinical and preclinical studies will highlight the significance of human microbiome as a promising target towards precision medicine in cancer therapies.

Funding

National Key Research and Development Program of China (2020YFA0907800), Shenzhen Science and Technology Innovation Program (KQTD20200820145822023) and National Natural Science Foundation of China (31900056 and 32000096).

The Role of The Tumor Microbiome in Tumor Development and Its Treatment

Commensal bacteria and other microorganisms that reside in the human body are closely associated with the development and treatment of cancers. Recently, tumor microbiome (TM) has been identified in a variety of cancers such as pancreatic, lung, and breast cancers. TM has different compositions in different tumors and has different effects on tumors. TM plays an important role in the formation of the tumor microenvironment, regulation of local immunity, and modification of tumor cell biology, and directly affects the efficacy of drug treatment for tumors. TM is expected to be a biomarker for tumors, and engineered tumor-targeting bacteria and anti-cancer microbial agents (GEN-001) have an important role in the treatment of tumors. This paper reviews the relevant studies on TM in recent years and describes its distribution in different tumors, its correlation with clinical features, its effect on local immunity, and the research directions of TM in tumor treatment.

Cancer pharmacomicrobiomics: targeting microbiota to optimise cancer therapy outcomes

Despite the promising advances in novel cancer therapy such as immune checkpoint inhibitors (ICIs), limitations including therapeutic resistance and toxicity remain. In recent years, the relationship between gut microbiota and cancer has been extensively studied. Accumulating evidence reveals the role of microbiota in defining cancer therapeutic efficacy and toxicity. Unlike host genetics, microbiota can be easily modified via multiple strategies, including faecal microbiota transplantation (FMT), probiotics and antibiotics. Preclinical studies have identified the mechanisms on how microbes influence cancer treatment outcomes. Clinical trials have also demonstrated the potential of microbiota modulation in cancer treatments. Herein, we review the mechanistic insights of gut microbial interactions with chemotherapy and ICIs, particularly focusing on the interplay between gut bacteria and the pharmacokinetics (eg, metabolism, enzymatic degradation) or pharmacodynamics (eg, immunomodulation) of cancer treatment. The translational potential of basic findings in clinical settings is then explored, including using microbes as predictive biomarkers and microbial modulation by antibiotics, probiotics, prebiotics, dietary modulations and FMT. We further discuss the current limitations of gut microbiota modulation in patients with cancer and suggest essential directions for future study. In the era of personalised medicine, it is crucial to understand the microbiota and its interactions with cancer. Manipulating the gut microbiota to augment cancer therapeutic responses can provide new insights into cancer treatment.

Small molecules in the big picture of gut microbiome-host cross-talk

Research on the gut microbiome and related diseases is rapidly growing with the development of sequencing technologies. An increasing number of studies offer new perspectives on disease development or treatment. Among these, the mechanisms of gut microbial metabolite-mediated effects merit better understanding. In this review, we first summarize the shifts in gut microbial metabolites within complex diseases, in which metabolites have correlational and occasionally causal effects on diseases and discuss the reported mechanisms. We further investigate the interactions between gut microbes and drugs, providing insights for precision medication as well as limitations of current research. Finally, we provide new research directions and research strategies for the development of drugs from gut microbial metabolites. FUNDING STATEMENT: None.

The role of gut microbiota in the development of colorectal cancer: a review

PURPOSE

Colorectal cancer (CRC) is the cancer of the colon and rectum. Recent research has found a link between CRC and human gut microbiota. This review explores the effect of gut microbiota on colorectal carcinogenesis and the development of chemoresistance.

METHODS

A literature overview was performed to identify the gut microbiota species that showed altered abundance in CRC patients and the mechanisms by which some of them aid in the development of chemoresistance.

RESULTS

Types of gut microbiota present and methods of analyzing them were discussed. We observed that numerous microbiota showed altered abundance in CRC patients and could act as a biomarker for CRC diagnosis and treatment. Further, it was demonstrated that microbes also have a role in the development of chemoresistance by mechanisms like immune system activation, drug modification, and autophagy modulation. Finally, the key issue of the growing global problem of antimicrobial resistance and its relationship with CRC was highlighted.

CONCLUSION

This review discussed the role of gut microbiota dysbiosis on colorectal cancer progression and the development of chemoresistance.

Complex Role of Microbiome in Pancreatic Tumorigenesis: Potential Therapeutic Implications

Pancreatic cancer (PC) is the fourth leading cause of cancer-related mortality with limited diagnostic and therapeutic options. Although immunotherapy has shown promise in the treatment of several cancers, its role in pancreatic cancer is rather limited. Several studies have focused on determining the role of the tumor microenvironment with cancer-cell-intrinsic events and tumor-infiltrating immune cellular properties. However, in the past decade, there has been emerging research aimed at delineating the role of the host microbiome, including the metabolites from microbes and host responses, on pancreatic tumorigenesis. Importantly, there is emerging evidence suggesting the beneficial role of a gut microbiome transplant to improve immunotherapeutic outcomes in cancer patients. In this review, we summarize the recent understanding of the role of the microbiome in pancreatic cancer progression, along with its clinical diagnostic and therapeutic implications.

The interplay between anticancer challenges and the microbial communities from the gut

Cancer being an increasing burden on human health, the use of anticancer drugs has risen over the last decades. The physiological effects of these drugs are not only perceived by the host's cells but also by the microbial cells it harbors as commensals, notably the gut microbiota. Since the early '50 s, the cytotoxicity of anticancer chemotherapy was evaluated on bacteria revealing some antimicrobial activities that result in an established perturbation of the gut microbiota. This perturbation can affect the host's health through dysbiosis, which can lead to multiple complications, but has also been shown to have a direct effect on the treatment efficiency.We, therefore, conducted a review of literature focusing on this triangular relationship involving the microbial communities from the gut, the host's disease, and the anticancer treatment. We focused specifically on the antimicrobial effects of anticancer chemotherapy, their impact on mutagenesis in bacteria, and the perspectives of using bacteria-based tools to help in the diagnostic and treatment of cancer.

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.