Facultative or obligate anaerobic bacteria have the potential for multimodality therapy of solid tumours

Intratumoral microbiota for hepatocellular carcinoma: from preclinical mechanisms to clinical cancer treatment

Intratumoral microbiota has been found to be a crucial component of hepatocellular carcinoma (HCC). Due to insufficient recognition, technical limitations, and low biomass of intratumoral microbiota, it is poorly understood. Intratumoral microbiota exhibit significant diversity in HCC tissues. It is involved in the development of HCC through several mechanisms, such as remodeling the immunosuppressive microenvironment, metabolic reprogramming, and genetic alterations. Moreover, intratumoral microbiota is associated with the metastasis of HCC cells. Herein, we reviewed the history of intratumoral microbiota, applied biotechnology to depict the signatures of intratumoral microbiota, investigated the potential sources of intratumoral microbiota, and assessed their functions, mechanisms, and heterogeneity. Furthermore, in this review, we summarized the development of therapeutics that can be used in the treatment of HCC and proposed future perspectives for research in this field.

Friends close, enemies closer: the complex role of the microbiome in antitumor immunity

Immunotherapy has achieved remarkable advances in cancer treatment by harnessing the immune system to combat tumors, yet its effectiveness remains inconsistent across patients and tumor types. The microbiota, a diverse assemblage of microorganisms residing at host barrier surfaces, is pivotal in shaping immune responses. This review explores the direct and indirect mechanisms via which the microbiota modulates antitumor immune responses both locally within the tumor microenvironment and systemically by affecting distant tumors. We discuss recent findings linking microbiota-derived metabolites and microbiota-derived antigens with antitumor immunity and immunotherapy response. Additionally, we discuss recent advances in microbiome-based therapies, including fecal microbiota transplantation. We propose the use and development of new analytical techniques to further characterize the complex functions and interactions between the microbiome and immune system. To conclude, we outline recommendations for future research and therapeutic approaches to leverage the microbiome to improve current immunotherapies.

Could intratumoural microbiota be key to unlocking treatment responses in hepatocellular carcinoma?

Hepatocellular carcinoma (HCC) is the third cause of cancer-related mortality worldwide. Current treatments include surgery and immunotherapy with variable response. Despite aggressive treatment, disease progression remains the biggest contributor to mortality. Thus, there is an urgent unmet need to improve current treatments through a better understanding of HCC tumourigenesis. The gut microbiota has been intensively examined in the context of HCC, with evidence showing gut modulation has the potential to modulate tumourigenesis and prognosis. In addition, recent literature suggests the presence of an intratumoural microbiota that may exert significant impacts on the development of solid tumours including HCC. By drawing parallels between the gut and hepatic/tumoural microbiota, we explore in the present review how the hepatic microbiota is established, its impact on tumourigenesis, and how modulation of the gut and hepatic microbiota may be key to improving current treatments of HCC. In particular, we highlight key bacteria that have been discovered in HCC tumours, and how they may affect the tumour immune microenvironment and HCC tumourigenesis. We then explore current therapies that target the intratumoural microbiota. With a deeper understanding of how the intratumoural microbiota is established, how different bacteria may be involved in HCC tumourigenesis, and how they can be targeted, we hope to spark future research in validating intratumoural microbiota as an avenue for improving treatment responses in HCC.

Fusobacterium nucleatum in tumors: from tumorigenesis to tumor metastasis and tumor resistance

Fusobacterium nucleatum, an anaerobic Gram-negative bacterium primarily residing in the oral cavity, has garnered significant attention for its emerging role in cancer progression and prognosis. While extensive research has revealed mechanistic links between Fusobacterium nucleatum and colorectal cancer, a comprehensive review spanning its presence and metastatic implications in cancers beyond colorectal origin is conspicuously absent. This paper broadens our perspective from colorectal cancer to various malignancies associated with Fusobacterium nucleatum, including oral, pancreatic, esophageal, breast, and gastric cancers. Our central focus is to unravel the mechanisms governing Fusobacterium nucleatum colonization, initiation, and promotion of metastasis across diverse cancer types. Additionally, we explore Fusobacterium nucleatum's adverse impacts on cancer therapies, particularly within the domains of immunotherapy and chemotherapy. Furthermore, this paper underscores the clinical research significance of Fusobacterium nucleatum as a potential tumor biomarker and therapeutic target, offering a novel outlook on its applicability in cancer detection and prognostic assessment.

Beyond Tumor Borders: Intratumoral Microbiome Effects on Tumor Behavior and Therapeutic Responses

The human body contains a diverse array of microorganisms, which exert a significant impact on various physiological processes, including immunity, and can significantly influence susceptibility to various diseases such as cancer. Recent advancements in metagenomic sequencing have uncovered the role of intratumoral microbiome, which covertly altered the development of cancer, the growth of tumors, and the response to existing treatments through multiple mechanisms. These mechanisms involve mainly DNA damage induction, oncogenic signaling pathway activation, and the host's immune response modulation. To explore novel therapeutic options and effectively target and regulate the intratumoral microbiome, a comprehensive understanding of these processes is indispensable. Here, we will explore various potential actions of the intratumoral microbiome concerning the initiation and progression of tumors. We will examine its impact on responses to chemotherapy, radiotherapy, and immunotherapy. Additionally, we will discuss the current state of knowledge regarding the use of genetically modified bacteria as a promising treatment option for cancer.

Tumor microenvironment: A playground for cells from multiple diverse origins

Tumor microenvironment is formed by various cellular and non-cellular components which interact with one another and form a complex network of interactions. Some of these cellular components also attain a secretory phenotype and release growth factors, cytokines, chemokines etc. in the surroundings which are capable of inducing even greater number of signalling networks. All these interactions play a decisive role in determining the course of tumorigenesis. The treatment strategies against cancer also exert their impact on the local microenvironment. Such interactions and anticancer therapies have been found to induce more deleterious outcomes like immunosuppression and chemoresistance in the process of tumor progression. Hence, understanding the tumor microenvironment is crucial for dealing with cancer and chemoresistance. This review is an attempt to develop some understanding about the tumor microenvironment and different factors which modulate it, thereby contributing to tumorigenesis. Along with summarising the major components of tumor microenvironment and various interactions taking place between them, it also throws some light on how the existing and potential therapies exert their impact on these dynamics.

Hypoxia as a Target for Combination with Transarterial Chemoembolization in Hepatocellular Carcinoma

Hypoxia is a hallmark of solid tumors, including hepatocellular carcinoma (HCC). Hypoxia has proven to be involved in multiple tumor biological processes and associated with malignant progression and resistance to therapy. Transarterial chemoembolization (TACE) is a well-established locoregional therapy for patients with unresectable HCC. However, TACE-induced hypoxia regulates tumor angiogenesis, energy metabolism, epithelial-mesenchymal transition (EMT), and immune processes through hypoxia-inducible factor 1 (HIF-1), which may have adverse effects on the therapeutic efficacy of TACE. Hypoxia has emerged as a promising target for combination with TACE in the treatment of HCC. This review summarizes the impact of hypoxia on HCC tumor biology and the adverse effects of TACE-induced hypoxia on its therapeutic efficacy, highlighting the therapeutic potential of hypoxia-targeted therapy in combination with TACE for HCC.

Insights into the enigma of oral streptococci in carcinogenesis

SUMMARYThe genus Streptococcus consists of a taxonomically diverse group of Gram-positive bacteria that have earned significant scientific interest due to their physiological and pathogenic characteristics. Within the genus Streptococcus, viridans group streptococci (VGS) play a significant role in the oral ecosystem, constituting approximately 80% of the oral biofilm. Their primary role as pioneering colonizers in the oral cavity with multifaceted interactions like adherence, metabolic signaling, and quorum sensing contributes significantly to the complex dynamics of the oral biofilm, thus shaping oral health and disease outcomes. Perturbations in oral streptococci composition drive oral dysbiosis and therefore impact host-pathogen interactions, resulting in oral inflammation and representing VGS as an opportunistic pathogen. The association of oral streptococci in tumors across distant organs, spanning the esophagus, stomach, pancreas, and colon, illuminates a potential association between oral streptococci, inflammation, and tumorigenesis. This finding emphasizes the need for further investigations into the role of oral streptococci in mucosal homeostasis and their involvement in carcinogenesis. Hence, here, we review the significance of oral streptococci in biofilm dynamics and how the perturbation may impact mucosal immunopathogenesis in the context of cancer, with a vision of exploiting oral streptococci for cancer intervention and for the development of non-invasive cancer diagnosis.

Bacteria-driven cancer therapy: Exploring advancements and challenges

Cancer, a serious fatal disease caused by the uncontrolled growth of cells, is the biggest challenge flagging around medicine and health fields. Conventionally, various treatments-based strategies such as radiotherapy, chemotherapy, and alternative cancer therapies possess drugs that cannot reach the cancerous tissues and make them toxic to noncancerous cells. Cancer immunotherapy has made outstanding achievements in reducing the chances of cancer. Our considerable attention towards cancer-directed immune responses and the mechanisms behind which immune cells kill cancer cells have progressively been helpful in the advancement of new therapies. Among them, bacteria-based cancer immunotherapy has achieved much more attention due to smart and robust mechanisms in activating the host anti-tumor response. Moreover, bacterial-based therapy can be utilized as a single monotherapy or in combination with multiple anticancer immunotherapies to accelerate productive clinical results. Herein, we comprehensively reviewed recent advancements, challenges, and future perspectives in developing bacterial-based cancer immunotherapies.

Intratumor microbiota: a novel tumor component

Bacteria have been found in tumors for over 100 years, but the irreproducibility of experiments on bacteria, the limitations of science and technology, and the contamination of the host environment have severely hampered most research into the role of bacteria in carcinogenesis and cancer treatment. With the development of molecular tools and techniques (e.g., macrogenomics, metabolomics, lipidomics, and macrotranscriptomics), the complex relationships between hosts and different microorganisms are gradually being deciphered. In the past, attention has been focused on the impact of the gut microbiota, the site where the body's microbes gather most, on tumors. However, little is known about the role of microbes from other sites, particularly the intratumor microbiota, in cancer. In recent years, an increasing number of studies have identified the presence of symbiotic microbiota within a large number of tumors, bringing the intratumor microbiota into the limelight. In this review, we aim to provide a better understanding of the role of the intratumor microbiota in cancer, to provide direction for future experimental and translational research, and to offer new approaches to the treatment of cancer and the improvement of patient prognosis.

Hacking the Immune Response to Solid Tumors: Harnessing the Anti-Cancer Capacities of Oncolytic Bacteria

Oncolytic bacteria are a classification of bacteria with a natural ability to specifically target solid tumors and, in the process, stimulate a potent immune response. Currently, these include species of Klebsiella, Listeria, Mycobacteria, Streptococcus/Serratia (Coley's Toxin), Proteus, Salmonella, and Clostridium. Advancements in techniques and methodology, including genetic engineering, create opportunities to "hijack" typical host-pathogen interactions and subsequently harness oncolytic capacities. Engineering, sometimes termed "domestication", of oncolytic bacterial species is especially beneficial when solid tumors are inaccessible or metastasize early in development. This review examines reported oncolytic bacteria-host immune interactions and details the known mechanisms of these interactions to the protein level. A synopsis of the presented membrane surface molecules that elicit particularly promising oncolytic capacities is paired with the stimulated localized and systemic immunogenic effects. In addition, oncolytic bacterial progression toward clinical translation through engineering efforts are discussed, with thorough attention given to strains that have accomplished Phase III clinical trial initiation. In addition to therapeutic mitigation after the tumor has formed, some bacterial species, referred to as "prophylactic", may even be able to prevent or "derail" tumor formation through anti-inflammatory capabilities. These promising species and their particularly favorable characteristics are summarized as well. A complete understanding of the bacteria-host interaction will likely be necessary to assess anti-cancer capacities and unlock the full cancer therapeutic potential of oncolytic bacteria.

Current advances in microbial-based cancer therapies

Microbes have an immense metabolic capability and can adapt to a wide variety of environments; as a result, they share complicated relationships with cancer. The goal of microbial-based cancer therapy is to treat patients with cancers that are not easily treatable, by using tumor-specific infectious microorganisms. Nevertheless, a number of difficulties have been encountered as a result of the harmful effects of chemotherapy, radiotherapy, and alternative cancer therapies, such as the toxicity to non-cancerous cells, the inability of medicines to penetrate deep tumor tissue, and the ongoing problem of rising drug resistance in tumor cells. Due to these difficulties, there is now a larger need for designing alternative strategies that are more effective and selective when targeting tumor cells. The fight against cancer has advanced significantly owing to cancer immunotherapy. The researchers have greatly benefited from their understanding of tumor-invading immune cells as well as the immune responses that are specifically targeted against cancer. Application of bacterial and viral cancer therapeutics offers promising potential to be employed as cancer treatments among immunotherapies. As a novel therapeutic strategy, microbial targeting of tumors has been created to address the persisting hurdles of cancer treatment. This review outlines the mechanisms by which both bacteria and viruses target and inhibit the proliferation of tumor cells. Their ongoing clinical trials and possible modifications that can be made in the future have also been addressed in the following sections. These microbial-based cancer medicines have the ability to suppress cancer that builds up and multiplies in the tumor microenvironment and triggers antitumor immune responses, in contrast to other cancer medications.

Arginine deiminase produced by lactic acid bacteria as a potent anti-cancer drug

Bacterial-based cancer immunotherapy has recently gained widespread attention due to its exceptional mechanism of rich pathogen-associated molecular patterns in anti-cancer immune responses. Contrary to conventional cancer therapies such as surgery, chemotherapy, radiation and phototherapy, bacteria-based cancer immunotherapy has the unique ability to suppress cancer by selectively accumulating and growing in tumours. In the view of this, several bacterial strains are being used for the treatment of cancer. Of which, lactic acid bacteria are a powerful, albeit still inadequately understood bacteria that possess a wide source of bioactive chemicals. Lactic acid bacteria metabolites, such as bacteriocins, short-chain fatty acids, exopolysaccharides show antitumour property. Amino acid pathways, which have lately been focussed as a new strategy to cancer therapy, are key element of the adaptability and dysregulation of metabolic pathways identified in proliferation of tumour cells. Arginine metabolism, in particular, has been shown to be critical for cancer therapy. As a result, better understanding of arginine metabolism in LAB and cancer cells could lead to new cancer therapeutic targets. This review will outline current advances in the interaction of arginine metabolism with cancer therapy and propose an arginine deiminase expression system to combat cancer more effectively.

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

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

Fundamentals of utilizing microbes in advanced cancer therapeutics: Current understanding and potential applications

One of the biggest health related issues in the twenty-first century is cancer. The current therapeutic platforms have not advanced enough to keep up with the number of rising cases. The traditional therapeutic approaches frequently fail to produce the desired outcomes. Therefore, developing new and more potent remedies is crucial. Recently, investigating microorganisms as potential anti-cancer treatments have garnered a lot of attention. Tumor-targeting microorganisms are more versatile at inhibiting cancer than the majority of standard therapies. Bacteria preferentially gather and thrive inside tumors, where they can trigger anti-cancer immune responses. They can be further trained to generate and distribute anticancer drugs based on clinical requirements using straightforward genetic engineering approaches. To improve clinical outcomes, therapeutic strategies utilizing live tumor-targeting bacteria can be used either alone or in combination with existing anticancer treatments. On the other hand, oncolytic viruses that target cancer cells, gene therapy via viral vectors, and viral immunotherapy are other popular areas of biotechnological investigation. Therefore, viruses serve as a unique candidate for anti-tumor therapy. This chapter describes the role of microbes, primarily bacteria and viruses in anti-cancer therapeutics. The various approaches to utilizing microbes in cancer therapy are discussed and examples of microorganisms that are now in use or that are undergoing experimental research are briefly discussed. We further point out the hurdles and the prospects of microbes-based remedies for cancer treatment.

Anti-Tumor Effects of Engineered VNP20009-Abvec-Igκ-mPD-1 Strain in Melanoma Mice via Combining the Oncolytic Therapy and Immunotherapy

Programmed cell death protein 1/Programmed cell death ligand 1 (PD-1/PD-L1) immune checkpoint inhibitors are the most promising treatments for malignant tumors currently, but the low response rate limits their further clinical utilization. To address this problem, our group constructed an engineered strain of VNP20009-Abvec-Igκ-mPD-1 [V-A-mPD-1 (mPD-1, murine PD-1)] to combine oncolytic bacterial therapy with immunotherapy. Further, we evaluated its growth performance and mPD-1 expression ability in vitro while establishing the melanoma mice model to explore its potential anti-cancer effects in tumor therapy. Our results indicated that the V-A-mPD-1 strain has superior growth performance and can invade B16F10 melanoma cells and express PD-1. In addition, in the melanoma mice model, we observed a marked reduction in tumor volume and the formation of a larger necrotic area. V-A-mPD-1 administration resulted in a high expression of mPD-1 at the tumor site, inhibiting tumor cell proliferation via the down-regulation of the expression of rat sarcoma (Ras), phosphorylated mitogen-activated protein kinase (p-MEK)/MEK, and phosphorylated extracellular signal-regulated kinase (p-ERK)/ERK expression significantly inhibited tumor cell proliferation. Tumor cell apoptosis was promoted by down-regulating phosphoinositide 3 kinase (PI3K) and protein kinase B (AKT) signaling pathways, as evidenced by an increased Bcl-2-associated X protein/B cell lymphoma-2 (Bax/Bcl-2) expression ratio. Meanwhile, the expression levels of systemic inflammatory cytokines, such as interleukin-6 (IL-6), interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α), were substantially reduced. In conclusion, our research demonstrated that V-A-mPD-1 has an excellent anti-tumor effect, prompting that the combined application of microbial therapy and immunotherapy is a feasible cancer treatment strategy.

Bacterial Peptides and Bacteriocins as a Promising Therapy for Solid Tumor

The conventional treatment is faced with limitations in treating solid tumors due to their specific pathophysiology. Several novel therapeutics have been introduced in recent decades to treat solid tumors. Among these new methods, tumor therapy using bacterial products like bacteriocins and peptides has been of great interest due to their unique characteristics and advantages of them in comparison to the conventional treatment, including that they can precisely target tumor cells, selective toxicity for tumor cells, low side effect on normal cells, toxicity activity for MDR cancer cells, used as the target delivery vehicles and enhancing drug delivery. Moreover, their small size and low molecular weight have made them easy to synthesize and modify. Furthermore, in recent years, genetic engineering has expanded the therapeutic ability of peptides to treat solid tumors, which results in overcoming the peptide drawbacks. The present review mainly focuses on the new advances in applying bacterial peptides and bacteriocins in treating human solid tumors.

Future prospects of bacteria-mediated cancer therapies: Affliction or opportunity?

Cancer, as a disease characterized by uncontrolled growth of cells, is recognized as one of the significant challenges in the field of health and medicine. There are various treatments for cancer like surgery, hormone therapy, chemotherapy, etc., but they have negative effects on the patient's lifestyle. Numerous side effects, and recently the emergence of drug resistance to these methods are weaknesses of these treatments. The utilization of bacteria as a treatment for cancer has attracted scientists' attention in the last decade. There are various methods of using bacteria to treat cancer, including the use of live, attenuated, or genetically engineered microbes, the use of bacterial toxins as an immunotoxin or conjugated to tumor antigens, bacteria-based cancer immunotherapy, bacterial vectors for gene-directed enzyme prodrug, and also the undeniable role of probiotics in treatment, are the cases that today are used for treatment. Bacterial therapy has shown a greater promise in cancer treatment due to its ability to lyse the tumor cells and deliver therapeutic products. However, the potential cytotoxicity of bacteria for healthy tissues, their inability to entirely lyse cancerous cells, and the possibility of mutations in their genomes are among the challenges of bacteriotherapy for cancer. Herein, we summarize the mechanism of bacteria, their potential benefits and harms, and the future of research in this field.

Recombinant Attenuated Salmonella enterica as a Delivery System of Heterologous Molecules in Cancer Therapy

Simple Summary

Cancer is among the main causes of death of millions of individuals worldwide. Although survival has improved with conventional treatments, the appearance of resistant cancer cells leads to patient relapses. It is, therefore, necessary to find new antitumor therapies that can completely eradicate transformed cells. Bacteria-based tumor therapy represents a promising alternative treatment, particularly the use of live-attenuated Salmonella enterica, with its potential use as a delivery system of antitumor heterologous molecules such as tumor-associated antigens, cytotoxic molecules, immunomodulatory molecules, pro-apoptotic proteins, nucleic acids, and nanoparticles. In this review, we present the state of the art of current preclinical and clinical research on the use of Salmonella enterica as a potential therapeutic ally in the war against cancer.

Abstract

Over a century ago, bacterial extracts were found to be useful in cancer therapy, but this treatment modality was obviated for decades. Currently, in spite of the development and advances in chemotherapies and radiotherapy, failure of these conventional treatments still represents a major issue in the complete eradication of tumor cells and has led to renewed approaches with bacteria-based tumor therapy as an alternative treatment. In this context, live-attenuated bacteria, particularly Salmonella enterica, have demonstrated tumor selectivity, intrinsic oncolytic activity, and the ability to induce innate or specific antitumor immune responses. Moreover, Salmonella enterica also has strong potential as a delivery system of tumor-associated antigens, cytotoxic molecules, immunomodulatory molecules, pro-apoptotic proteins, and nucleic acids into eukaryotic cells, in a process known as bactofection and antitumor nanoparticles. In this review, we present the state of the art of current preclinical and clinical research on the use of Salmonella enterica as a potential therapeutic ally in the war against cancer.

The Use of Bacteria in Cancer Treatment: A Review from the Perspective of Cellular Microbiology

Cellular microbiology, which is the interaction between harmful microbes and infected cells, is important in the determination of the bacterial infection processes and in the progression of data of different cellular mechanisms. The therapeutic role of bacteria has gained attention since the known methods such as radiation, chemotherapy, and immunotherapy have got drawbacks. Bacteria have demonstrated a favorable impact in treating cancer through eradication of tumors. Bacteria, in cancer treatment, have proven to be promising and have been shown in some of the previous work that it can successfully suppress the growth of tumors. In this paper, we analyzed the difficulties and settlement for using bacteria in cancer therapy as well the mechanisms in which bacteria works in order to achieve tumor eradication. Future works may focus on the use of bacteria along with other treatments in order to achieve effective tumor therapy.

A Hybrid Imaging Platform(CT/PET/FMI) for Evaluating Tumor Necrosis and Apoptosis in Real-Time

Multimodality imaging is an advanced imaging tool for monitoring tumor behavior and therapy in vivo. In this study, we have developed a novel hybrid tri-modality system that includes two molecular imaging methods: positron emission computed tomography (PET) and fluorescence molecular imaging (FMI) and the anatomic imaging modality X-ray computed tomography (CT). The following paper describes the system development. Also, its imaging performance was tested in vitro (phantom) and in vivo, in Balb/c nude mice bearing a head and neck tumor xenograft treated with novel gene therapy [a new approach to the delivery of recombinant bacterial gene (IL-24-expressing strain)]. Using the tri-modality imaging system, we simultaneously monitored the therapeutic effect, including the apoptotic and necrotic induction within the tumor in vivo. The apoptotic induction was examined in real-time using an 18F-ML-10 tracer; the cell death was detected using ICG. A CT was used to evaluate the anatomical situation. An increased tumor inhibition (including tumor growth and tumor cell apoptosis) was observed in the treatment group compared to the control groups, which further confirmed the therapeutic effect of a new IL-24-expressing strain gene therapy on the tumor in vivo. By being able to offer concurrent morphological and functional information, our system is able to characterize malignant tissues more accurately. Therefore, this new tri-modality system (PET/CT/FMI) is an effective imaging tool for simultaneously investigating and monitoring tumor progression and therapy outcomes in vivo.

Bacterially mediated drug delivery and therapeutics: Strategies and advancements

It was already clinically apparent 150 years ago that bacterial therapy could alleviate diseases. Recently, a burgeoning number of researchers have been using bacterial regimens filled with microbial therapeutic leads to diagnose and treat a wide range of disorders and diseases, including cancers, inflammatory diseases, metabolic disorders and viral infections. Some bacteria that were designed to have low toxicity and high efficiency in drug delivery have been used to treat diseases successfully, especially in tumor therapy in animal models or clinical trials, thanks to the progress of genetic engineering and synthetic bioengineering. Therefore, genetically engineered bacteria can serve as efficient drug delivery vehicles, carrying nucleic acids or genetic circuits that encode and regulate therapeutic payloads. In this review, we summarize the development and applications of this approach. Strategies for genetically modifying strains are described in detail, along with their objectives. We also describe some controlled strategies for drug delivery and release using these modified strains as carriers. Furthermore, we discuss treatment methods for various types of diseases using engineered bacteria. Tumors are discussed as the most representative example, and other diseases are also briefly described. Finally, we discuss the challenges and prospects of drug delivery systems based on these bacteria.

Genetically modified cancer vaccines: Current status and future prospects

Vaccines can stimulate the immune system to protect individuals from infectious diseases. Moreover, vaccines have also been applied to the prevention and treatment of cancers. Due to advances in genetic engineering technology, cancer vaccines could be genetically modified to increase antitumor efficacy. Various genes could be inserted into cells to boost the immune response, such as cytokines, T cell costimulatory molecules, tumor-associated antigens, and tumor-specific antigens. Genetically modified cancer vaccines utilize innate and adaptive immune responses to induce durable antineoplastic capacity and prevent the recurrence. This review will discuss the major approaches used to develop genetically modified cancer vaccines and explore recent advances to increase the understanding of engineered cancer vaccines.

Engineering Bacteria and Bionic Bacterial Derivatives with Nanoparticles for Cancer Therapy

Natural bacteria are interesting subjects for cancer treatments owing to their unique autonomy-driven and hypoxic target properties. Genetically modified bacteria (such as bacteria with msbB gene and aroA gene modifications) can effectively cross sophisticated physiological barriers and transport antitumor agents into deep tumor tissues, and they have good biosafety. Additionally, bacteria can secrete cytokines (such as interleukin-224, interferon-gamma [IFN-γ], and interleukin-1β) and activate antitumor immune responses in the tumor microenvironment, resulting in tumor inhibition. All of these characteristics can be easily utilized to develop synergistic antitumor strategies by combining bacteria-based agents with other therapeutic approaches. Herein, representative studies of bacteria-instructed multimodal synergistic cancer therapy are introduced (e.g., photothermal therapy, chemoimmunotherapy, photodynamic therapy, and photocontrolled bacterial metabolite therapy), and their key advantages are systematically expounded. The current challenges and future prospects in advancing the development of bacteria-based micro/nanomedicines in the field of synthetic biology research are also emphasized, which will hopefully promote the development of related bacteria-based cancer therapies.

Bacteria-Assisted Transport of Nanomaterials to Improve Drug Delivery in Cancer Therapy

Currently, the design of nanomaterials for the treatment of different pathologies is presenting a major impact on biomedical research. Thanks to this, nanoparticles represent a successful strategy for the delivery of high amounts of drugs for the treatment of cancer. Different nanosystems have been designed to combat this pathology. However, the poor penetration of these nanomaterials into the tumor tissue prevents the drug from entering the inner regions of the tumor. Some bacterial strains have self-propulsion and guiding capacity thanks to their flagella. They also have a preference to accumulate in certain tumor regions due to the presence of different chemo-attractants factors. Bioconjugation reactions allow the binding of nanoparticles in living systems, such as cells or bacteria, in a simple way. Therefore, bacteria are being used as a transport vehicle for nanoparticles, facilitating their penetration and the subsequent release of the drug inside the tumor. This review would summarize the literature on the anchoring methods of diverse nanosystems in bacteria and, interestingly, their advantages and possible applications in cancer therapy.

Bacterial-Based Cancer Therapy (BBCT): Recent Advances, Current Challenges, and Future Prospects for Cancer Immunotherapy

Currently approximately 10 million people die each year due to cancer, and cancer is the cause of every sixth death worldwide. Tremendous efforts and progress have been made towards finding a cure for cancer. However, numerous challenges have been faced due to adverse effects of chemotherapy, radiotherapy, and alternative cancer therapies, including toxicity to non-cancerous cells, the inability of drugs to reach deep tumor tissue, and the persistent problem of increasing drug resistance in tumor cells. These challenges have increased the demand for the development of alternative approaches with greater selectivity and effectiveness against tumor cells. Cancer immunotherapy has made significant advancements towards eliminating cancer. Our understanding of cancer-directed immune responses and the mechanisms through which immune cells invade tumors have extensively helped us in the development of new therapies. Among immunotherapies, the application of bacteria and bacterial-based products has promising potential to be used as treatments that combat cancer. Bacterial targeting of tumors has been developed as a unique therapeutic option that meets the ongoing challenges of cancer treatment. In comparison with other cancer therapeutics, bacterial-based therapies have capabilities for suppressing cancer. Bacteria are known to accumulate and proliferate in the tumor microenvironment and initiate antitumor immune responses. We are currently well-informed regarding various methods by which bacteria can be manipulated by simple genetic engineering or synthetic bioengineering to induce the production of anti-cancer drugs. Further, bacterial-based cancer therapy (BBCT) can be either used as a monotherapy or in combination with other anticancer therapies for better clinical outcomes. Here, we review recent advances, current challenges, and prospects of bacteria and bacterial products in the development of BBCTs.

The intratumoral microbiome: Characterization methods and functional impact

Live-pathogenic bacteria, which were identified inside tumors hundreds year ago, are key elements in modern cancer research. As they have a relatively accessible genome, they offer a multitude of metabolic engineering opportunities, useful in several clinical fields. Better understanding of the tumor microenvironment and its associated microbiome would help conceptualize new metabolically engineered species, triggering efficient therapeutic responses against cancer. Unfortunately, given the low microbial biomass nature of tumors, characterizing the tumor microbiome remains a challenge. Tumors have a high host versus bacterial DNA ratio, making it extremely complex to identify tumor-associated bacteria. Nevertheless, with the improvements in next-generation analytic tools, recent studies demonstrated the existence of intratumor bacteria inside defined tumors. It is now proven that each cancer subtype has a unique microbiome, characterized by bacterial communities with specific metabolic functions. This review provides a brief overview of the main approaches used to characterize the tumor microbiome, and of the recently proposed functions of intracellular bacteria identified in oncological entities. The therapeutic aspects of live-pathogenic microbes are also discussed, regarding the tumor microenvironment of each cancer type.

Highlights of Immunomodulation in Salmonella-Based Cancer Therapy

Bacteria-mediated cancer therapy (BMCT) is an emerging tool that may advance potential approaches in cancer immunotherapy, whereby tumors are eradicated by the hosts’ immune system upon recruitment and activation by bacteria such as Salmonella. This paper provides an emphasis on the immunomodulatory effects that encompasses both the innate and adaptive immune responses inherently triggered by Salmonella. Furthermore, modifications of Salmonella-based treatment in the attempt to improve tumor-specific immune responses including cytokine therapy, gene therapy, and DNA vaccine delivery are likewise discussed. The majority of the findings described herein incorporate cell-based experiments and murine model studies, and only a few accounts describe clinical trials. Salmonella-based cancer therapy is still under development; nonetheless, the pre-clinical research and early-phase clinical trials that have been completed so far have shown promising and convincing results. Certainly, the continuous development of, and innovation on, Salmonella-based therapy could pave the way for its eventual emergence as one of the mainstream therapeutic interventions addressing various types of cancer.

Colorectal cancer treatment using bacteria: focus on molecular mechanisms

BACKGROUND

Colorectal cancer which is related to genetic and environmental risk factors, is among the most prevalent life-threatening cancers. Although several pathogenic bacteria are associated with colorectal cancer etiology, some others are considered as highly selective therapeutic agents in colorectal cancer. Nowadays, researchers are concentrating on bacteriotherapy as a novel effective therapeutic method with fewer or no side effects to pay the way of cancer therapy. The introduction of advanced and successful strategies in bacterial colorectal cancer therapy could be useful to identify new promising treatment strategies for colorectal cancer patients.

MAIN TEXT

In this article, we scrutinized the beneficial effects of bacterial therapy in colorectal cancer amelioration focusing on different strategies to use a complete bacterial cell or bacterial-related biotherapeutics including toxins, bacteriocins, and other bacterial peptides and proteins. In addition, the utilization of bacteria as carriers for gene delivery or other known active ingredients in colorectal cancer therapy are reviewed and ultimately, the molecular mechanisms targeted by the bacterial treatment in the colorectal cancer tumors are detailed.

CONCLUSIONS

Application of the bacterial instrument in cancer treatment is on its way through becoming a promising method of colorectal cancer targeted therapy with numerous successful studies and may someday be a practical strategy for cancer treatment, particularly colorectal cancer.

Anticancer activity of Helicobacter pylori ribosomal protein (HPRP) with iRGD in treatment of colon cancer

PURPOSE

As the conventional therapeutic approaches were not completely successful in the treatment of colon cancer, there is still a need for finding the most efficient therapeutic agents. Here we investigated the anticancer activity of HPRP-A1 that was derived from the N-terminal region of Helicobacter pylori ribosomal protein L1 (RpL1) alone or in combination with tumor-homing peptide iRGD and 5-Fluorouracil (5FU) on colon cancer cell lines (CT26 and HT29) and isograft models of colon cancer.

METHOD

We assessed the tumor growth inhibitory activity of HPRP-A1 with or without iRGD and 5FU on colon cancer in vitro and in vivo. In the in vitro part, we investigate the effect of HPRP-A1 alone and in combination with iRGD/5FU.

RESULTS

Our results demonstrated that co-administration of HPRP-A1 with iRGD increased the apoptosis, while these two peptides in combination with 5FU increased the intracellular level of p53 that upregulate the pro-apoptotic gene BAX and downregulate the anti-apoptotic gene BCL2. HPRP-A1 blocks the cell cycle progression in G0/G1. Co-administration of two peptides significantly reduced the size and weight of the tumors, while the group that received 5FU in combination with the peptides increased the necrotic and decrease the fibrotic area significantly in the tumor tissues, which also disrupt the oxidant/antioxidant balance.

CONCLUSIONS

Our results indicated that HPRP-A1 could be considered an effective agent toward colon cancer in vitro and in vivo with the ability to enhance the effects of conventional chemotherapy agent 5FU.

Multidimensional role of bacteria in cancer: Mechanisms insight, diagnostic, preventive and therapeutic potential

The active role of bacteria in oncogenesis has long been a topic of debate. Although, it was speculated to be a transmissible cause of cancer as early as the 16th-century, yet the idea about the direct involvement of bacteria in cancer development has only been explored in recent decades. More recently, several studies have uncovered the mechanisms behind the carcinogenic potential of bacteria which are inflammation, immune evasion, pro-carcinogenic metabolite production, DNA damage and genomic instability. On the other side, the recent development on the understanding of tumor microenvironment and technological advancements has turned this enemy into an ally. Studies using bacteria for cancer treatment and detection have shown noticeable effects. Therapeutic abilities of bioengineered live bacteria such as high specificity, selective cytotoxicity to cancer cells, responsiveness to external signals and control after ingestion have helped to overcome the challenges faced by conventional cancer therapies and highlighted the bacterial based therapy as an ideal approach for cancer treatment. In this review, we have made an effort to compile substantial evidence to support the multidimensional role of bacteria in cancer. We have discussed the multifaceted role of bacteria in cancer by highlighting the wide impact of bacteria on different cancer types, their mechanisms of actions in inducing carcinogenicity, followed by the diagnostic and therapeutic potential of bacteria in cancers. Moreover, we have also highlighted the existing gaps in the knowledge of the association between bacteria and cancer as well as the limitation and advantage of bacteria-based therapies in cancer. A better understanding of these multidimensional roles of bacteria in cancer can open up the new doorways to develop early detection strategies, prevent cancer, and develop therapeutic tactics to cure this devastating disease.

The onco-immunological implications of Fusobacterium nucleatum in breast cancer

Breast cancer is a leading cause of death worldwide and a better understanding of this disease is needed to improve treatment outcomes. Recent evidence indicates that bacterial dysbiosis is associated with breast cancer, but the bacteria involved remain poorly characterised. Furthermore, an association between periodontal disease, characterised by oral dysbiosis, and breast cancer have also been discovered, but the mechanisms responsible for this association remains to be elucidated. The oral bacterium involved in periodontal disease, Fusobacterium nucleatum, have recently been detected in human breast tumour tissue and it promoted tumour growth and metastatic progression in a mouse model. The mechanisms of how F. nucleatum might colonise breast tissue and how it might promote tumour progression has not been fully elucidated yet. Here we discuss the breast tumour microbiota, its colonisation by F. nucleatum, possible mechanisms by which F. nucleatum might promote breast cancer progression and how this might impact breast cancer treatment. Literature indicates that F. nucleatum might promote breast cancer progression through activating the Toll-like receptor 4 pathway and by supressing the immune system. This results in cell growth and treatment resistance through autophagy as well as immune evasion. Targeted treatment directed at F. nucleatum combined with immunotherapy and autophagy inhibitors might therefore be a feasible treatment strategy for breast cancer patients.

Novel insights into the role of Clostridium novyi-NT related combination bacteriolytic therapy in solid tumors

Several solid tumors (for example leiomyosarcoma, melanoma and hepatocellular carcinoma) possess areas of hypoxia, which underlies one of the primary reasons of failure of conventional anticancer therapies. The areas of poor vascularization are insensitive to radiotherapy and chemotherapeutic drugs. Conversely, the hypoxic regions of tumors provide an ideal environment for anaerobic bacteria. The attenuated anaerobic bacterium, Clostridium novyi-NT (C. novyi-NT), is highly sensitive to oxygen and can target the destruction of hypoxic and necrotic areas of tumors, inducing oncolysis and characteristics indicative of an immune response. Theoretically, chemotherapy, radiotherapy and immunotherapy combined with bacterial therapy can be used as a novel means of treating solid tumors, promoting tumor regression and inhibiting metastasis formation with a notable beneficial effect. The present review discusses the molecular mechanisms of combined bacteriolytic therapy, predominantly focusing on C. novyi-NT, and summarizes the findings of previous studies on experimental animal models, including its efficacy and safety via different drug delivery routes. This strategy has great potential to overcome the limitations of conventional cancer therapy, resulting in improved treatments, and thus potentially improved outcomes for patients.

Bacteriotherapy in gastrointestinal cancer

The most prevalent gastrointestinal (GI) cancers include colorectal cancer, stomach cancer, and liver cancer, known as the most common causes of cancer-related death in both men and women populations in the world. Traditional therapeutic approaches, including surgery, radiotherapy, and chemotherapy have failed in the effective treatment of cancer. Therefore, there is an urgent need for finding new effective anticancer agents. The available evidence and also the promising results of using bacteria as the anticancer agents on numerous cancer cell lines have attracted the attention of scientists for the therapeutic role of bacteria in the field of cancer therapy. Moreover, several studies on the bacteriotherapy agents have used genetic engineering to overcome the challenges and enhance the efficacy with the least drawbacks. Numerous bacterial species that can specifically target and internalize into the tumor cells are used live, attenuated, or genetically as compared to selectively consider the hypoxic condition of tumor, which results in the tumor suppression. The present study is a comprehensive review of the current literature on the use of bacteria and their substances such as bacteriocins and toxins in the treatment of different types of gastrointestinal cancers.

Bacteria and cancer: Different sides of the same coin

Conventional cancer therapies such as chemotherapy, radiation therapy, and immunotherapy due to the complexity of cancer have been unsuccessful in the complete eradication of tumor cells. Thus, there is a need for new therapeutic strategies toward cancer. Recently, the therapeutic role of bacteria in different fields of medicine and pharmaceutical research has attracted attention in recent decades. Although several bacteria are notorious as cancer-causing agents, recent research revealed intriguing results suggesting the bacterial potential in cancer therapy. Thus, bacterial cancer therapy is an alternative anticancer approach that has promising results on tumor cells in-vivo. Moreover, with the aid of genetic engineering, some natural or genetically modified bacterial strains can directly target hypoxic regions of tumors and secrete therapeutic molecules leading to cancer cell death. Additionally, stimulation of immune cells by bacteria, bacterial cancer DNA vaccine and antitumor bacterial metabolites are other therapeutic applications of bacteria in cancer therapy. The present study is a comprehensive review of different aspects of bacterial cancer therapy alone and in combination with conventional methods, for improving cancer therapy.

Studying the effects of several heat-inactivated bacteria on colon and breast cancer cells

A great number of researches over the last years are allocated to know cancer reasons, prevention and treatment strategies. Bacterial infections are one of the promoting factors in cancer development. The present study was carried out to study effects of heat-killed bacteria on cancer cell lines MCF7 and HT-29. To this purpose, four bacterial strains including Salmonella typhi, Staphylococcus epidermidis, Escherichia coli and Pseudomonas aeruginosa were assayed. Thermal inactivation method was used to kill the bacteria and preserve the bacterial surface proteins unchangeable. The concentrations of 0.01, 0.1, 0.5 and 1 mg/ml of inactivated bacteria were prepared to evaluate the effects of heat-inactivated bacterial solutions on MCF7 and HT-29 cell lines. MTT assay was used to measure the cell viability of cancer cells treated with different concentration of inactivated bacterial solutions.The MTT assay results after 48 hours showed that the heat-killed bacterial solutions were able to induce the proliferation of both cancer cell lines. In addition, the most cell viability in MCF-7 cell line was seen in samples treated with S. epidermidis, while in HT29 cells, the most one was seen in S. typhi treated samples. It was concluded that bacterial infections are cancer-deteriorating agents, and any species of bacteria is specific to certain cancerous tissue.

The role of bacterial toxins and spores in cancer therapy

Cancer is one of the leading causes of human death worldwide. Conventional anticancer therapies are ineffective in treating cancer patients due to various reasons. Thus, more effective and accessible alternative anticancer strategies have been evolved with time with high specificity towards tumor cells and with less or no adverse effects to normal cells. One such promising therapy is the use of bacterial toxins and spores to treat advanced solid tumors. Initially, Coley paved the way towards the bacterial anticancer therapy several decades ago and now it has emerged as a potential tool to eliminate tumor cells. Bacterial spores of obligate anaerobes exclusively germinate in the hypoxic/necrotic areas and not in the well-oxygenated areas of the body. This unique phenomenon has been exploited in using bacterial spores as a remedy for cancer. Bacterial toxins also play a significant role in either directly killing tumor cells or altering the cellular processes of the tumor cells which ultimately leads to the inhibition and regression of the solid tumor. With the advancement of molecular techniques, a number of genetically-modified non-pathogenic bacteria have been developed to use in bacterial anticancer strategies. Although promising results have shown so far, further investigations are required to ensure the efficacy and the safety of the bacterial spores and toxins in treating cancer.

The microbiome and cancer for clinicians

The human microbiome is an emerging target in cancer development and therapeutics. It may be directly oncogenic, through promotion of mucosal inflammation or systemic dysregulation, or may alter anti-cancer immunity/therapy. Microorganisms within, adjacent to and distant from tumors may affect cancer progression, and interactions and differences between these populations can influence the course of disease. Here we review the microbiome as it pertains to cancer for clinicians. The microbiota of cancers including colorectal, pancreas, breast and prostate are discussed. We examine "omics" technologies, microbiota associated with tumor tissue and tumor-site fluids such as feces and urine, as well as indirect effects of the gut microbiome. We describe roles of the microbiome in immunotherapy, and how it can be modulated to improve cancer therapeutics. While research is still at an early stage, there is potential to exploit the microbiome, as modulation may increase efficacy of treatments, reduce toxicities and prevent carcinogenesis.

Therapeutic bacteria to combat cancer; current advances, challenges, and opportunities

Successful treatment of cancer remains a challenge, due to the unique pathophysiology of solid tumors, and the predictable emergence of resistance. Traditional methods for cancer therapy including radiotherapy, chemotherapy, and immunotherapy all have their own limitations. A novel approach is bacteriotherapy, either used alone, or in combination with conventional methods, has shown a positive effect on regression of tumors and inhibition of metastasis. Bacteria-assisted tumor-targeted therapy used as therapeutic/gene/drug delivery vehicles has great promise in the treatment of tumors. The use of bacteria only, or in combination with conventional methods was found to be effective in some experimental models of cancer (tumor regression and increased survival rate). In this article, we reviewed the major advantages, challenges, and prospective directions for combinations of bacteria with conventional methods for tumor therapy.

Salmonella-Based Targeted Cancer Therapy: Updates on A Promising and Innovative Tumor Immunotherapeutic Strategy

Presently, cancer is one of the leading causes of death in the world, primarily due to tumor heterogeneity associated with high-grade malignancy. Tumor heterogeneity poses a tremendous challenge, especially with the emergence of resistance not only to chemo- and radiation- therapies, but also to immunotherapy using monoclonal antibodies. The use of Salmonella, as a highly selective and penetrative antitumor agent, has shown convincing results, thus meriting further investigation. In this review, the mechanisms used by Salmonella in combating cancer are carefully explained. In essence, Salmonella overcomes the suppressive nature of the tumor microenvironment and coaxes the activation of tumor-specific immune cells to induce cell death by apoptosis and autophagy. Furthermore, Salmonella treatment suppresses tumor aggressive behavior via inhibition of angiogenesis and delay of metastatic activity. Thus, harnessing the natural potential of Salmonella in eliminating tumors will provide an avenue for the development of a promising micro-based therapeutic agent that could be further enhanced to address a wide range of tumor types.

HPV, hypoxia and radiation response in head and neck cancer

Over the last decades, the incidence of human papilloma virus (HPV) positive head and neck squamous-cell carcinoma (HNSCC) has significantly increased. Infection with high-risk HPV types drives tumourigenesis through expression of the oncoproteins E6 and E7. Currently, the primary treatment of HNSCC consists of radiotherapy, often combined with platinum-based chemotherapeutics. One of the common features of HNSCC is the occurrence of tumour hypoxia, which impairs the efficacy of radiotherapy and is a negative prognostic factor. Therefore, it is important to detect and quantify the severity of hypoxia, as well as develop strategies to specifically target hypoxic tumours. HPV-positive tumours are remarkably radiosensitive compared to HPV-negative tumours and consequently the HPV-positive patients have a better prognosis. This provides an opportunity to elucidate mechanisms of radiation sensitivity, which may reveal targets for improved therapy for HPV-negative head and neck cancers. In this review, we will discuss the differences between HPV-positive and HPV-negative head and neck tumours and methods of hypoxia detection and targeting in these disease types. Particular emphasis will be placed on the mechanisms by which HPV infection impacts radiosensitivity.

Cancer Immunotherapy: Priming the Host Immune Response with Live Attenuated Salmonella enterica

In recent years, cancer immunotherapy has undergone great advances because of our understanding of the immune response and the mechanisms through which tumor cells evade it. A century after the first immunotherapy attempt based on bacterial products described by William Coley, the use of live attenuated bacterial vectors has become a promising alternative in the fight against cancer. This review describes the role of live attenuated Salmonella enterica as an oncolytic and immunotherapeutic agent, due to its high affinity for tumor tissue and its ability to activate innate and adaptive antitumor immune response. Furthermore, its potential use as delivery system of tumor antigens and immunomodulatory molecules that induce tumor regression is also reviewed.

The role of bacteria in cancer therapy - enemies in the past, but allies at present

In recent decades, bacteria’s therapeutic role has aroused attention in medicinal and pharmaceutical research. While bacteria are considered among the primary agents for causing cancer, recent research has shown intriguing results suggesting that bacteria can be effective agents for cancer treatment – they are the perfect vessels for targeted cancer therapy. Several bacterial strains/species have been discovered to possess inherent oncolytic potentials to invade and colonize solid tumors in vivo. The therapeutic strategy of using bacteria for treating cancer is considered to be effective; however, the severe side effects encountered during the treatment resulted in the abandonment of the therapy. State-of-the-art genetic engineering has been recently applied to bacteria therapy and resulted in a greater efficacy with minimum side effects. In addition, the anti-cancer potential of tumor-targeting bacteria through oral administration circumvents the use of the intravenous route and the associated adverse effects. This review aims to provide a comprehensive summary of the latest literature on the role of bacteria in cancer treatment.

Treatment of Neuroblastoma with an Engineered "Obligate" Anaerobic Salmonella typhimurium Strain YB1

Purpose Neuroblastoma is an embryonic solid tumor derived from the progenitors of the sympathetic nervous system. More than half of the patients developed metastatic disease at the time of initial diagnosis and had poor outcome with current therapeutic approaches. In recent years, some obligate and facultative anaerobic bacteria were reported to target the hypoxic and necrotic region of solid tumor models and caused tumor regression. We recently successfully constructed an "obligate" anaerobic Salmonella strain YB1 that was applied in breast cancer nude mice model by us. Here, we report the application of YB1 in neuroblastoma treatment. Methods The anti-cancer effect and side-effects of YB1 was examined in both in vitro and in vivo experiment. Previous established orthotopic neuroblastoma SCID/beige murine model using SK-NLP/luciferase cell line was adopted. ResultsIn vitro, YB1 induced apoptosis for up to 31.4% of the neuroblastoma cells under anaerobic condition, three times more than that under aerobic condition (10.9%). The expression of both Toll like Receptor 4 and 5 (TLR4 and TLR5) in cancer cells were significantly up-regulated (p<0.05, p<0.01 respectively) after the treatment of YB1 under anaerobic condition. In mouse model, YB1 preferentially accumulated inside the core of the tumors, rather than in normal tissues as our previous reported. This is suggestive of the hypoxic nature of tumor core. Tumor growth was significantly retarded in YB1 treatment group (n=6, P<0.01). Furthermore, there was no long-term organ damage noted in all the organs examined including heart, lung, liver, spleen and brain in the YB1 treated mice. Conclusion The genetic modified Salmonella strain YB1 is a promising anti-tumor strategy against the tumor bulk for neuroblastoma. Future study can be extended to other common cancer types to verify the relative efficacy on different neoplastic cells.

Drug delivery with living cells

The field of drug delivery has grown tremendously in the past few decades by developing a wide range of advanced drug delivery systems. An interesting category is cell-based drug delivery, which includes encapsulation of drugs inside cells or attached to the surface and subsequent transportation through the body. Another approach involves genetic engineering of cells to secrete therapeutic molecules in a controlled way. The next-generation systems integrate expertise from synthetic biology to generate therapeutic gene networks for highly advanced sensory and output devices. These developments are very exciting for the drug delivery field and could radically change the way we administer biological medicines to chronically ill patients. This review is covering the use of living cells, either as transport system or production-unit, to deliver therapeutic molecules and bioactive proteins inside the body. It describes a wide range of approaches in cell-based drug delivery and highlights exceptional examples.

[Salmonella enterica: an ally in the therapy of cancer]

Salmonella enterica, a species of facultative anaerobic bacteria, has demonstrated success as a live-attenuated bacterial vector for vaccination. S. enterica has also demonstrated promise as a therapeutic agent against cancer. Pre-clinical and clinical trials have shown that S. enterica is localized in both solid and semi-solid tumors as well as in metastatic tumors. Moreover, S. enterica reduces resistance to treatment with other agents. In this review we present the novel therapeutic anti-cancer approaches that use S. enterica both for its ability as a delivery system for heterologous moieties against cancer and for its direct anti-cancer properties.

Tumor-targeting bacterial therapy: A potential treatment for oral cancer (Review)

Certain obligate or facultative anaerobic bacteria, which exhibit an inherent ability to colonize solid tumors in vivo, may be used in tumor targeting. As genetically manipulated bacteria may actively and specifically penetrate into the tumor tissue, bacterial therapy is becoming a promising approach in the treatment of tumors. However, to the best of our knowledge, no reports have been published thus far regarding the bacterial treatment of oral cancer, one of the most common types of cancer worldwide. In this review, the progress in the understanding of bacterial strategies used in tumor-targeted therapy is discussed and particular bacterial strains that may have great therapeutic potential in oral squamous cell carcinoma (OSCC) tumor-targeted therapy are predicted as determined by previous studies.

Effects of some natural immunomodulatory compounds in combination with thalidomide on survival rate and tumor size in fibrosarcoma-bearing mice

PURPOSE

Despite significant advances have been achieved in cancer therapy, response to conventional treatments like surgery, radiotherapy and chemotherapy varies among individuals. Immunotherapy is known to be an effective strategy for patients who are resistant to the currently available interventions.

METHODS

Ninety-six male Balb/c mice (aged 6-8 weeks) were selected and divided into twelve groups of eight. Approximately, 1&times;10(6)of WEHI-164 cells were injected to each mouse for tumor genesis. Five immunotherapy treatments were considered in this study, including Heat Shock Proteins (HSP), Bacillus Calmette-Gu&eacute;rin (BCG), Bifidobacterium, Immuno-Modulator Drug (IMOD) and Thalidomide. After tumor formation, the groups were treated with one or more of these therapies. Tumor size and survival rate was regularly monitored.

RESULTS

Depending on the treatment group, tumor sizes were different. In some groups, combined treatments demonstrated more inhibitory effects on tumor growth rate. The mice in group (IMOD+ Thalidomide) had the lowest survival rate but group (BCG+ HSP+ Thalidomide) survived until the end of the experiment.

CONCLUSION

The (HSP+ BCG+ Thalidomide) group exhibited satisfactory outcomes and two third of the mice in this group went into complete remission. Some combination therapies in test groups had significant impacts on survival and tumor growth rate.