Exogeneous Cytosine Deaminase Gene Expression in Bifidobacterium breve I-53-8w for Tumor-Targeting Enzyme/Prodrug Therapy

Microbial Therapy and Breast Cancer Management: Exploring Mechanisms, Clinical Efficacy, and Integration within the One Health Approach

This comprehensive review elucidates the profound relationship between the human microbiome and breast cancer management. Recent findings highlight the significance of microbial alterations in tissue, such as the gut and the breast, and their role in influencing the breast cancer risk, development, progression, and treatment outcomes. We delve into how the gut microbiome can modulate systemic inflammatory responses and estrogen levels, thereby impacting cancer initiation and therapeutic drug efficacy. Furthermore, we explore the unique microbial diversity within breast tissue, indicating potential imbalances brought about by cancer and highlighting specific microbes as promising therapeutic targets. Emphasizing a holistic One Health approach, this review underscores the importance of integrating insights from human, animal, and environmental health to gain a deeper understanding of the complex microbe-cancer interplay. As the field advances, the strategic manipulation of the microbiome and its metabolites presents innovative prospects for the enhancement of cancer diagnostics and therapeutics. However, rigorous clinical trials remain essential to confirm the potential of microbiota-based interventions in breast cancer management.

Do Bacteria Provide an Alternative to Cancer Treatment and What Role Does Lactic Acid Bacteria Play?

Cancer is one of the leading causes of mortality and morbidity worldwide. According to 2022 statistics from the World Health Organization (WHO), close to 10 million deaths have been reported in 2020 and it is estimated that the number of cancer cases world-wide could increase to 21.6 million by 2030. Breast, lung, thyroid, pancreatic, liver, prostate, bladder, kidney, pelvis, colon, and rectum cancers are the most prevalent. Each year, approximately 400,000 children develop cancer. Treatment between countries vary, but usually includes either surgery, radiotherapy, or chemotherapy. Modern treatments such as hormone-, immuno- and antibody-based therapies are becoming increasingly popular. Several recent reports have been published on toxins, antibiotics, bacteriocins, non-ribosomal peptides, polyketides, phenylpropanoids, phenylflavonoids, purine nucleosides, short chain fatty acids (SCFAs) and enzymes with anticancer properties. Most of these molecules target cancer cells in a selective manner, either directly or indirectly through specific pathways. This review discusses the role of bacteria, including lactic acid bacteria, and their metabolites in the treatment of cancer.

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.

In Situ Delivery and Production System (iDPS) of Anti-Cancer Molecules with Gene-Engineered Bifidobacterium

To selectively and continuously produce anti-cancer molecules specifically in malignant tumors, we have established an in situ delivery and production system (iDPS) with Bifidobacterium as a micro-factory of various anti-cancer agents. By focusing on the characteristic hypoxia in cancer tissue for a tumor-specific target, we employed a gene-engineered obligate anaerobic and non-pathogenic bacterium, Bifidobacterium, as a tool for systemic drug administration. This review presents and discusses the anti-tumor effects and safety of the iDPS production of numerous anti-cancer molecules and addresses the problems to be improved by directing attention mainly to the hallmark vasculature and so-called enhanced permeability and retention effect of tumors.

A Resource for Cloning and Expression Vectors Designed for Bifidobacteria: Overview of Available Tools and Biotechnological Applications

Bifidobacteria represent an important group of (mostly) commensal microorganisms, which have enjoyed increasing scientific and industrial attention due to their purported health-promoting attributes. For the latter reason, several species have been granted "generally recognized as safe" (GRAS) and "qualified presumption of safety" (QPS) status by the Food and Drugs Administration (FDA) and European Food Safety Authority (EFSA) organizations. Increasing scientific evidence supports their potential as oral delivery vectors to produce bioactive and therapeutic molecules at intestinal level. In order to achieve an efficient utilization of bifidobacterial strains as health-promoting (food) ingredients, it is necessary to provide evidence on the molecular mechanisms behind their purported beneficial and probiotic traits, and precise mechanisms of interaction with their human (or other mammalian) host. In this context, developing appropriate molecular tools to generate and investigate recombinant strains is necessary. While bifidobacteria have long remained recalcitrant to genetic manipulation, a wide array of Bifidobacterium-specific replicating vectors and genetic modification procedures have been described in literature. The current chapter intends to provide an updated overview on the vectors used to genetically modify and manipulate bifidobacteria, including their general characteristics, reviewing examples of their use to successfully generate recombinant bifidobacterial strains for specific purposes, and providing a general workflow and cautions to design and conduct heterologous expression in bifidobacteria. Knowledge gaps and fields of research that may help to widen the molecular toolbox to improve the functional and technological potential of bifidobacteria are also discussed.

The Microbiome and Cancer: Creating Friendly Neighborhoods and Removing the Foes Within

The human body is colonized by the microbial cells that are estimated to be as abundant as human cells, yet their genome is roughly 100 times the human genome, providing significantly more genetic diversity. The past decade has observed an explosion of interest in examining the existence of microbiota in the human body and understanding its role in various diseases including inflammatory bowel disease, neurologic diseases, cardiovascular disorders, and cancer. Many studies have demonstrated differential community composition between normal tissue and cancerous tissue, paving the way for investigations focused on deciphering the cause-and-effect relationships between specific microbes and initiation and progression of various cancers. Also, evolving are the strategies to alter tumor-associated dysbiosis and move it toward eubiosis with holistic approaches to change the entire neighborhood or to neutralize pathogenic strains. In this review, we discuss important pathogenic bacteria and the underlying mechanisms by which they affect cancer progression. We summarize key microbiota alterations observed in multiple tumor niches, their association with clinical stages, and their potential use in cancer diagnosis and management. Finally, we discuss microbiota-based therapeutic approaches.

Engineering the gut microbiota to treat chronic diseases

Gut microbes play vital roles in host health and disease. A number of commensal bacteria have been used as vectors for genetic engineering to create living therapeutics. This review highlights recent advances in engineering gut bacteria for the treatment of chronic diseases such as metabolic diseases, cancer, inflammatory bowel diseases, and autoimmune disorders. KEY POINTS: • Bacterial homing to tumors has been exploited to deliver therapeutics in mice models. • Engineered bacteria show promise in mouse models of metabolic diseases. • Few engineered bacterial treatments have advanced to clinical studies.

Bifidobacterium spp: the promising Trojan Horse in the era of precision oncology

Selective delivery of therapeutic agents into solid tumors has been a major challenge impeding the achievement of long-term disease remission and cure. The need to develop alternative drug delivery routes to achieve higher drug concentration in tumor tissue, reduce unwanted off-target side effects and thus achieve greater therapeutic efficacy, has resulted in an explosive body of research. Bifidobacterium spp. are anaerobic, nonpathogenic, Gram-positive bacteria, commensal to the human gut that are a possible anticancer drug-delivery vehicle. In this review, we describe Bifidobacterium's microbiology, current clinical applications, overview of the preclinical work investigating Bifidobacterium's potential to deliver anticancer therapy, and review the different strategies used up to date. Finally, we discuss both current challenges and future prospects.

Antitumor mechanisms of bifidobacteria

Cancer remains one of the most common causes of mortality globally. Chemotherapy, one of the major treatment strategies for cancer, primarily functions by targeting the cancer cells and affecting them physiologically, but also affects normal cells, which is a major concern at present. Therefore, adverse effects of chemotherapy drugs, including myelosuppression and liver and kidney damage, are of concern. Now, microbial products have attracted attention in cancer treatment research. Notably, carcinogenesis is considered to be associated with microbial dysbiosis, particularly the positive antitumor effects of bifidobacteria. Although there remains a substantial amount to be understood about the regulation of bifidobacteria, bifidobacteria remain an attractive and novel source of cancer therapeutics. The present review focuses on introducing the latest information on the antitumor effects of bifidobacteria and to propose future strategies for using bifidobacteria in the development of cancer therapeutics.

Designer bacteria as intratumoural enzyme biofactories

Bacterial-directed enzyme prodrug therapy (BDEPT) is an emerging form of treatment for cancer. It is a biphasic variant of gene therapy in which a bacterium, armed with an enzyme that can convert an inert prodrug into a cytotoxic compound, induces tumour cell death following tumour-specific prodrug activation. BDEPT combines the innate ability of bacteria to selectively proliferate in tumours, with the capacity of prodrugs to undergo contained, compartmentalised conversion into active metabolites in vivo. Although BDEPT has undergone clinical testing, it has received limited clinical exposure, and has yet to achieve regulatory approval. In this article, we review BDEPT from the system designer's perspective, and provide detailed commentary on how the designer should strategize its development de novo. We report on contemporary advancements in this field which aim to enhance BDEPT in terms of safety and efficacy. Finally, we discuss clinical and regulatory barriers facing BDEPT, and propose promising approaches through which these hurdles may best be tackled.

Three-dimensional tumor spheroids for in vitro analysis of bacteria as gene delivery vectors in tumor therapy

Background

Several studies in animal models demonstrated that obligate and facultative anaerobic bacteria of the genera Bifidobacterium, Salmonella, or Clostridium specifically colonize solid tumors. Consequently, these and other bacteria are discussed as live vectors to deliver therapeutic genes to inhibit tumor growth. Therapeutic approaches for cancer treatment using anaerobic bacteria have been investigated in different mouse models. In the present study, solid three-dimensional (3D) multicellular tumor spheroids (MCTS) of the colorectal adenocarcinoma cell line HT-29 were generated and tested for their potential to study prodrug-converting enzyme therapies using bacterial vectors in vitro.

Results

HT-29 MCTS resembled solid tumors displaying all relevant features with an outer zone of proliferating cells and hypoxic and apoptotic regions in the core. Upon incubation with HT-29 MCTS, Bifidobacterium bifidum S17 and Salmonella typhimurium YB1 selectively localized, survived and replicated in hypoxic areas inside MCTS. Furthermore, spores of the obligate anaerobe Clostridium sporogenes germinated in these hypoxic areas. To further evaluate the potential of MCTS to investigate therapeutic approaches using bacteria as gene delivery vectors, recombinant bifidobacteria expressing prodrug-converting enzymes were used. Expression of a secreted cytosine deaminase in combination with 5-fluorocytosine had no effect on growth of MCTS due to an intrinsic resistance of HT-29 cells to 5-fluorouracil, i.e. the converted drug. However, a combination of the prodrug CB1954 and a strain expressing a secreted chromate reductase effectively inhibited MCTS growth.

Conclusions

Collectively, the presented results indicate that MCTS are a suitable and reliable model to investigate live bacteria as gene delivery vectors for cancer therapy in vitro.

Electronic supplementary material

The online version of this article (doi:10.1186/s12934-015-0383-5) contains supplementary material, which is available to authorized users.

Biomaterials at the interface of nano- and micro-scale vector-cellular interactions in genetic vaccine design

The development of safe and effective vaccines for the prevention of elusive infectious diseases remains a public health priority. Immunization, characterized by adaptive immune responses to specific antigens, can be raised by an array of delivery vectors. However, current commercial vaccination strategies are predicated on the retooling of archaic technology. This review will discuss current and emerging strategies designed to elicit immune responses in the context of genetic vaccination. Selected strategies at the biomaterial-biological interface will be emphasized to illustrate the potential of coupling both fields towards a common goal.

Mobilome and genetic modification of bifidobacteria

Until recently, proper development of molecular studies in Bifidobacterium species has been hampered by growth difficulties, because of their exigent nutritive requirements, oxygen sensitivity and lack of efficient genetic tools. These studies, however, are critical to uncover the cross-talk between bifidobacteria and their hosts' cells and to prove unequivocally the supposed beneficial effects provided through the endogenous bifidobacterial populations or after ingestion as probiotics. The genome sequencing projects of different bifidobacterial strains have provided a wealth of genetic data that will be of much help in deciphering the molecular basis of the physiological properties of bifidobacteria. To this end, the purposeful development of stable cloning and expression vectors based on robust replicons - either from temperate phages or resident plasmids - is still needed. This review addresses the current knowledge on the mobile genetic elements of bifidobacteria (prophages, plasmids and transposons) and summarises the different types of vectors already available, together with the transformation procedures for introducing DNA into the cells. It also covers recent molecular studies performed with such vectors and incipient results on the genetic modification of these organisms, establishing the basis that would allow the use of bifidobacteria for future biotechnological applications.

Bacterial vectors for imaging and cancer gene therapy: a review

The significant burden of resistance to conventional anticancer treatments in patients with advanced disease has prompted the need to explore alternative therapeutic strategies. The challenge for oncology researchers is to identify a therapy which is selective for tumors with limited toxicity to normal tissue. Engineered bacteria have the unique potential to overcome traditional therapies' limitations by specifically targeting tumors. It has been shown that bacteria are naturally capable of homing to tumors when systemically administered resulting in high levels of replication locally, either external to (non-invasive species) or within tumor cells (pathogens). Pre-clinical and clinical investigations involving bacterial vectors require relevant means of monitoring vector trafficking and levels over time, and development of bacterial-specific real-time imaging modalities are key for successful development of clinical bacterial gene delivery. This review discusses the currently available imaging technologies and the progress to date exploiting these for monitoring of bacterial gene delivery in vivo.

Accessing the inaccessible: molecular tools for bifidobacteria

Bifidobacteria are an important group of the human intestinal microbiota that have been shown to exert a number of beneficial probiotic effects on the health status of their host. Due to these effects, bifidobacteria have attracted strong interest in health care and food industries for probiotic applications and several species are listed as so-called "generally recognized as safe" (GRAS) microorganisms. Moreover, recent studies have pointed out their potential as an alternative or supplementary strategy in tumor therapy or as live vaccines. In order to study the mechanisms by which these organisms exert their beneficial effects and to generate recombinant strains that can be used as drug delivery vectors or live vaccines, appropriate molecular tools are indispensable. This review provides an overview of the currently available methods and tools to generate recombinant strains of bifidobacteria. The currently used protocols for transformation of bifidobacteria, as well as replicons, selection markers, and determinants of expression, will be summarized. We will further discuss promoters, terminators, and localization signals that have been used for successful generation of expression vectors.

Technological advances in bifidobacterial molecular genetics: application to functional genomics and medical treatments

Bifidobacteria are well known as beneficial intestinal bacteria that exert health-promoting effects in humans. In addition to physiological and immunological investigations, molecular genetic technologies have been developed and have recently started to be applied to clarify the molecular bases of host-Bifidobacterium interactions. These technologies include transformation technologies and Escherichia coli-Bifidobacterium shuttle vectors that enable heterologous gene expression. In this context, a plasmid artificial modification method that protects the introduced plasmid from the restriction system in host bifidobacteria has recently been developed to increase transformation efficiency. On the other hand, targeted gene inactivation systems, which are vital for functional genomics, seemed far from being practically applicable in bifidobacteria. However, remarkable progress in this technology has recently been achieved, enabling functional genomics in bifidobacteria. Integrated use of these molecular genetic technologies with omics-based analyses will surely boost characterization of the molecular basis underlying beneficial effects of bifidobacteria. Applications of recombinant bifidobacteria to medical treatments have also progressed.

Determination of the ribosome-binding sequence and spacer length between binding site and initiation codon for efficient protein expression in Bifidobacterium longum 105-A

The frequency of the ribosome-binding site (RBS) and spacer length between binding site and initiation codon were analyzed using informatics, and compared the activities of various synthetic RBSs and spacers in Bifidobacterium longum 105-A. As the result, AAGGAG and a 5 nt spacer length produced the most efficient protein expression.

Progress in genomics, metabolism and biotechnology of bifidobacteria

Members of the genus Bifidobacterium were first described over a century ago and were quickly associated with a healthy intestinal tract due to their numerical dominance in breast-fed babies as compared to bottle-fed infants. Health benefits elicited by bifidobacteria to its host, as supported by clinical trials, have led to their wide application as probiotic components of health-promoting foods, especially in fermented dairy products. However, the relative paucity of genetic tools available for bifidobacteria has impeded development of a comprehensive molecular understanding of this genus. In this review we present a summary of current knowledge on bifidobacterial metabolism, classification, physiology and genetics and outline the currently available methods for genetically accessing and manipulating the genus.

Genomic insights into bifidobacteria

Since the discovery in 1899 of bifidobacteria as numerically dominant microbes in the feces of breast-fed infants, there have been numerous studies addressing their role in modulating gut microflora as well as their other potential health benefits. Because of this, they are frequently incorporated into foods as probiotic cultures. An understanding of their full interactions with intestinal microbes and the host is needed to scientifically validate any health benefits they may afford. Recently, the genome sequences of nine strains representing four species of Bifidobacterium became available. A comparative genome analysis of these genomes reveals a likely efficient capacity to adapt to their habitats, with B. longum subsp. infantis exhibiting more genomic potential to utilize human milk oligosaccharides, consistent with its habitat in the infant gut. Conversely, B. longum subsp. longum exhibits a higher genomic potential for utilization of plant-derived complex carbohydrates and polyols, consistent with its habitat in an adult gut. An intriguing observation is the loss of much of this genome potential when strains are adapted to pure culture environments, as highlighted by the genomes of B. animalis subsp. lactis strains, which exhibit the least potential for a gut habitat and are believed to have evolved from the B. animalis species during adaptation to dairy fermentation environments.

A novel Bifidobacterium infantis-mediated TK/GCV suicide gene therapy system exhibits antitumor activity in a rat model of bladder cancer

Bladder cancer is the ninth most common malignancy in the world. Successful clinical management remains a challenge. In order To search for novel targeted and efficacious treatment, we sought to investigate anti-tumor activity of BI-TK suicide gene therapy system in a rat model of bladder tumors. We first constructed and tested an anaerobic Bifidobacterium infantis-mediated thymidine kinase (BI-TK) suicide gene therapy system. To test the in vivo efficacy of this system, we established a rat model of bladder tumors, which was induced by N-methyl-nitrosourea perfusion. Bifidobacterium infantis containing the HSV-TK (i.e., BI-TK) were constructed by transformation of recombinant plasmid pGEX - TK. The engineered BI-TK was injected into tumor-bearing rats via tail vein, followed by intraperitoneal injection of ganciclovir (GCV). Using the rat model of bladder tumors, we found that bladder tumor burdens were significantly lower in the rats treated with BI-TK/GCV group than that treated with normal saline control group (p <0.05). While various degrees of apoptosis of the tumor cells were detected in all groups using in situ TUNEL assay, apoptosis was mostly notable in the BI-TK/GCV treatment group. Immunohistochemical staining further demonstrated that the BI-TK/GCV treatment group had the highest level of caspase3 protein expression than that of the empty plasmid group and normal saline group (p < 0.05). Thus, our results demonstrate that the Bifidobacterium infantis-mediated TK/GCV suicide gene therapy system can effectively inhibit rat bladder tumor growth, possibly through increasing caspase 3 expression and inducing apoptosis.

Effect of LTA isolated from bifidobacteria on D-galactose-induced aging

BACKGROUND

Bifidobacteria are a natural part of the bacterial flora in the human body and have a symbiotic bacteria-host relationship with human beings. Aging is associated with reduced number of beneficial colonic bifidobacteria and impaired immunity. Lipoteichoic acid is a major constituent of the cell wall of bifidobacteria which is important for bacterial survival, growth, and function. The possible anti-aging effects of lipoteichoic acid isolated from bifidobacteria is presently unknown.

OBJECTIVE

The aim of the present study was to investigate possible anti-aging effects of lipoteichoic acid isolated from bifidobacteria on senescent mice artificially induced by chronic injection of d-galactose and explore potential anti-aging's mechanisms.

METHODS

Mice were artificially induced senescence by consecutive injection of d-galactose (100mg/kg) once daily for 7weeks and lipoteichoic acid from bifidobacterium bifidum, was simultaneously administered to them once a week by intraperitoneal infusion. Mice were sacrificed, blood and other samples were collected at the indicated time. Anti-oxidation activity in brain, histology of tissue, gene expression, lymphocyte's DNA damage and cytokine production of lymphocytes in vitro and in vivo were measured.

RESULTS

Lipoteichoic acid could significantly improve general appearance of the aging model mice, improve anti-oxidation activity in brain, increase IL-2 level and decrease TNF-alpha level in vitro and in vivo, respectively. Besides, LTA remarkably inhibited DNA damage in the both splenic lymphocytes and circulating lymphocytes. Moreover, LTA could decrease p16 expression while increase c-fos expression in the d-galactose treated mice.

CONCLUSION

Taken together, the results indicated, for the first time, that LTA could suppress the aging process via the following several mechanisms, including enhancement of anti-oxidation activity in brain, improvement of immune function and alteration of gene expression.

New strategies for cancer gene therapy: progress and opportunities

1. To date, cancer persists as one of the most devastating diseases worldwide. Problems such as metastasis and tumour resistance to chemotherapy and radiotherapy have seriously limited the therapeutic effects of existing clinical treatments. 2. To address these problems, cancer gene therapy has been developing over the past two decades, specifically designed to deliver therapeutic genes to treat cancers using vector systems. So far, a number of genes and delivery vehicles have been evaluated and significant progress has been made with several gene therapy modalities in clinical trials. However, the lack of an ideal gene delivery system remains a major obstacle for the successful translation of regimen to the clinic. 3. Recent understanding of hypoxic and necrotic regions within solid tumours and rapid development of recombinant DNA technology have reignited the idea of using anaerobic bacteria as novel gene delivery systems. These bacterial vectors have unique advantages over other delivery systems and are likely to become the vector of choice for cancer gene therapy in the near future. 4. Meanwhile, complicated tumour pathophysiology and associated metastasis make it hard to rely on a single therapeutic modality for complete tumour eradication. Therefore, the combination of cancer gene therapy with other conventional treatments has become paramount. 5. The present review introduces important cancer gene therapy strategies and major vector systems that have been studied so far with an emphasis on bacteria-mediated cancer gene therapy. In addition, exemplary combined therapies are briefly reviewed.

Effect of Bifidobacterium bifidum DSM 20082 cytoplasmic fraction on human immune cells

The objective of the present study was to determine the effect of the soluble cytoplasmic fraction from Bifidobacterium bifidum DSM 20082 (Bb) lysate on peripheral blood T cells. In peripheral blood mononuclear cells of healthy subjects, cytotoxic activity, proliferation, apoptosis, and up-regulation of CD8 or CD4 molecules in T cells were examined. When peripheral blood mononuclear cells were stimulated with Bb lysate, the main effect was observed in CD8+ cells as a significant increase of CD8 molecules in a dose-dependent manner, and this behavior was observed at 24, 48, and 72 h after stimulation; in contrast, stimulation with Bb lysate showed no effect on the up-regulation of CD4 molecules in T helper cells. Further Bb lysate did not induce proliferation activity in either CD8+ or CD4+ cells. Bb lysate induced activation of CD8+ cytotoxic activity against autologous monocytes. Around 80% of the cells stimulated with Bb lysate were positive to peanut agglutinin (PNA), suggesting that the stimulated CD8+ cells corresponded to activated/effector cellular populations. When apoptosis was determined, there were no differences between stimulated and non-stimulated cells. Our results indicate that Bb lysate is able to increase cytotoxic activity of peripheral CD8+ cells, without affecting lymphocyte survival.