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

Antibiotic Consumption in Primary Care in Costa Rica and Italy: A Retrospective Cross-Country Analysis

BACKGROUND AND OBJECTIVE

 The increasing emergence and spread of drug-resistant pathogens resulting from inappropriate antibiotic usage have become more evident in recent years, particularly with the rising incidence of methicillin-resistant Staphylococcus aureus (MRSA) infections. Since joining the Organization for Economic Cooperation and Development (OECD), Costa Rica can now compare its healthcare system with other countries, and similarities have been noted with Italy regarding health indicators. Both nations have universal healthcare systems, covering their entire populations, and hold similar positions in the Human Development Index (HDI). Consequently, the goal is to compare antibiotic prescribing and consumption patterns to collaboratively develop strategies against bacterial resistance.

METHODS

 In order to compare antibiotic consumption between regions, a standardized contrast was utilized, specifically using the defined daily dose (DDD). An Orthogonal Contrast test was performed to test the means, followed by the application of the Student's t-test on these contrasts. This analysis aimed to assess the potential influence of regions on DDD values. Antibiotic consumption data were collected between January 2021 and December 2022 from the Local Health Authority of Naples 3 South (LHANS) in Italy and IMS Health, Q Quintiles, and VIA by way of (IQVIA) reports in Costa Rica.

RESULTS

 LHANS shows a considerable disparity in gross expenditure compared to Italy's overall expenditure, while the private sector of Costa Rica exhibits even lower gross expenditure than Italy. Antibiotic consumption in Italy exceeds that of Costa Rica, with Costa Rica's consumption amounting to 47.70% of Italy's total consumption. Additionally, LHANS exhibited a 22.43% higher gross expenditure compared to the Campania region, emphasizing the variability in antibiotic usage within the same country The results indicated no statistically significant differences in antibiotic consumption between the regions, as none of the null hypotheses were rejected.

CONCLUSIONS

The study provides valuable insights into expenditure patterns and antibiotic consumption, highlighting the need for improved prescribing practices and awareness campaigns to address the issue of antibiotic resistance. The findings emphasize the importance of implementing international guidelines to combat the growing threat of antibiotic resistance and ensure the effective management of infectious diseases.

Synthetic engineered bacteria for cancer therapy

INTRODUCTION

Cancer mortality worldwide highlights the urgency for advanced therapeutic methods to fill the gaps in conventional cancer therapies. Bacteriotherapy is showing great potential in tumor regression due to the motility and colonization tendencies of bacteria. However, the complicated in vivo environment and tumor pathogenesis hamper the therapeutic outcomes. Synthetic engineering methods endow bacteria with flexible abilities both at the extracellular and intracellular levels to meet treatment requirements. In this review, we introduce synthetic engineering methods for bacterial modifications. We highlight the recent progress in engineered bacteria and explore how these synthetic methods endow bacteria with superior abilities in cancer therapy. The current clinical translations are further discussed. Overall, this review may shed light on the advancement of engineered bacteria for cancer therapy.

AREAS COVERED

Recent progress in synthetic methods for bacterial engineering and specific examples of their applications in cancer therapy are discussed in this review.

EXPERT OPINION

Bacteriotherapy bridges the gaps of conventional cancer therapies through the natural motility and colonization tendency of bacteria, as well as their synthetic engineering. Nevertheless, to fulfill the bacteriotherapy potential and move into clinical trials, more research focusing on its safety concerns should be conducted.

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.

Dual mode imaging guided multi-functional bio-targeted oxygen production probes for tumor therapy

Focused ultrasound ablation surgery (FUAS) is a novel therapy with a wide range of potential applications. However, synergists are crucial to the therapy process due to the ultrasonic energy's attenuation properties. As a result of the complex hypoxic environment in the tumor area and many factors, the existing synergists have limitations such as weak targeting, single imaging mode, and easy tumor recurrence after treatment. Because of the above deficiencies, this study intends to construct bio-targeted oxygen production probes consisting of Bifidobacterium that naturally target the hypoxia region of the tumor and multi-functional oxygen-producing nanoparticles equipped with IR780, perfluorohexane (PFH), CBP (carboplatin), and oxygen. The probes are expected to achieve targeted and synergistic FUAS therapy and dual-mode imaging to mediate tumor diagnosis and treatment. The oxygen and drugs carried in it are accurately released after FUAS stimulation, which is expected to alleviate tumor hypoxia, avoid tumor drug resistance, improve the effect of chemotherapy, and realize FUAS combined with chemotherapy antitumor therapy. This strategy is expected to make up for the deficiencies of existing synergists, improve the effectiveness and safety of treatment, and provide the foundation for future tumor therapy progress.

The Anti-Adhesion Effect of Nisin as a Robust Lantibiotic on the Colorectal Cancer Cells

Background

Bacteriocins are a type of antimicrobial peptide that are produced by probiotics. They have been studied as possible therapeutic drugs and have been used to suppress bacterial development in foods. Nisin is a potent bacteriocin having the anti-microbial and anti-cancer characteristics produced by Lactococcus lactis. The aim of the present paper is to evaluate the influence of Nisin on cell adhesion and its two related genes, mmp-2 and mmp-9, in the colorectal cancer cell line.

Materials and Methods

For this purpose, HT-29 cells were treated with various concentrations of Nisin and the cell cytotoxicity, cell adhesion, and gene expression were evaluated using the MTT assay, cell adhesion assay, and real-time PCR.

Results

Our findings showed that 32 to 1024 μg/ml of Nisin resulted in a significant reduction in cell viability (P < 0.05). Furthermore, 128 and 256 μg/ml of Nisin significantly reduced the cell adhesion, and mmp-2 and mmp-9 gene expressions (P < 0.05).

Conclusion

Our findings suggested that Nisin could prevent metastasis and cancer progression.

Fusobacterium nucleatum: a novel immune modulator in breast cancer?

Breast cancer was the most commonly diagnosed cancer worldwide in 2020. Greater understanding of the factors which promote tumour progression, metastatic development and therapeutic resistance is needed. In recent years, a distinct microbiome has been detected in the breast, a site previously thought to be sterile. Here, we review the clinical and molecular relevance of the oral anaerobic bacterium Fusobacterium nucleatum in breast cancer. F. nucleatum is enriched in breast tumour tissue compared with matched healthy tissue and has been shown to promote mammary tumour growth and metastatic progression in mouse models. Current literature suggests that F. nucleatum modulates immune escape and inflammation within the tissue microenvironment, two well-defined hallmarks of cancer. Furthermore, the microbiome, and F. nucleatum specifically, has been shown to affect patient response to therapy including immune checkpoint inhibitors. These findings highlight areas of future research needed to better understand the influence of F. nucleatum in the development and treatment of breast cancer.

The Association of Human Cytomegalovirus Infection and Colorectal Cancer: A Clinical Analysis

Background

Human cytomegalovirus (HCMV) commonly infects humans and establishes lifelong infection. It causes disease and increased mortality rates in patients with immunosuppression. HCMV gene products are found to be present in multiple human malignancies and target cellular functions involved in tumor development; additionally, a tumor-cytoreductive role of CMV has also been observed. The purpose of this study was to evaluate the correlation between CMV infection and the incidence of colorectal cancer (CRC).

Methods

The data were provided by a national database that is compliant with Health Insurance Portability and Accountability Act (HIPAA). Using International Classification of Disease (ICD)-10 and ICD-9 diagnostic codes, the data were filtered to evaluate patients infected with HCMV versus patients never infected with HCMV. Patient data from 2010 to 2019 were assessed. Access to the database was granted by Holy Cross Health, Fort Lauderdale for the purpose of academic research. Standard statistical methods were used.

Results

Between January 2010 and December 2019, the query was analyzed and resulted in 14,235 patients after matching in the infected and control groups. The groups were matched by age range, sex, Charlson Comorbidity Index (CCI) score, and treatment. The incidence of CRC was 1.159% (165 patients) in the HCMV group and 2.845% (405 patients) in the control group. The difference after matching was statistically significant by a P-value < 2.2 × 10^-16 with an odds ratio of 0.37 (95% confidence interval (CI) 0.32 - 0.42).

Conclusions

The study shows a statistically significant correlation between CMV infection and a reduced incidence of CRC. Further evaluation is recommended to assess the potential of CMV in reducing CRC incidence.

Living Gut Bacteria Functionalized with Gold Nanoclusters and Drug for Facile Cancer Theranostics

Bacbots are potent self-propelling vehicles for targeted therapy that can be guided by chemical and biochemical stimuli of the host. In addition, they can be guided externally by the use of magnetic field or other physical forces. The challenge is to incorporate drugs and diagnostic tools in living bacteria with retention of theranostic activity until reaching the targets and easy clearance of the remainder following the treatment. We report that living Lactobacillus rhamnosus, when functionalized with photoluminescent Au nanoclusters and the anticancer drug methotrexate, was cytotoxic to monolayer and spheroids of cancer cells (HeLa and HT29) even at a low dose of bacteria used (10⁷ cfu/mL). The observed cell death was nearly 90% in HeLa spheroids and 70% in HT29 spheroids. Further, functionalization of the bacterial surface with the nanoclusters helped incorporate the drug onto their cell surfaces. The drug and nanocluster-loaded bacteria annihilated the cells and the spheroids in a rather short time (6 h) that revealed the specificity and effectiveness of the bacbots. The bacbots exhibited synergistic toxicity on the cells as their effect was more than the drug and the bacteria individually. This higher toxicity could be associated with elevated levels of reactive oxygen species generated in the bacbot-treated cells. The multifunctional bacbots reported here provide an option for guided therapy with the natural variant of the human gut-friendly living bacteria without the need for attenuation or genetic modification.

Photothermal Nanoheaters-Modified Spores for Safe and Controllable Antitumor Therapy

Introduction

To present a safer tumor therapy based on bacteria and identify in detail how the activation and infection behavior of spores can be controlled remotely by near-infrared light (NIR-irradiation) based on nanoheaters' modification.

Methods

Spores bring a better tolerance to surface modification. Transitive gold-nanorods-allied-nanoclusters-modified spores (Spore@NRs/NCs) were constructed by covalent glutaraldehyde crosslink. The photothermal properties of nanoheaters before and after attachment to spores were studied by recording temperature-irradiation time curves. The controlled viability and infection behavior of Spore@NRs/NCs were investigated by NIR-irradiation.

Results

In this work, a controllable sterilizing effect to activated vegetative bacteria was obtained obviously. When met with a suitable growth-environment, Spore@NRs/NCs could germinate, activate into vegetative bacteria and continue to reproduce. Without NIR-irradiation, nanoheaters could not affect the activity of both spores and vegetative bacterial cells. However, with NIR-irradiation after incubating in growth medium, nanoheaters on spores could control the spores' germination and affect the growth curve as well as the viability of the vegetative bacterial cells. For Spore@NRs/NCs (Spore:NCs:NRs=1:1:4, 67.5 μg mL^-1), a ~98% killing rate of vegetative bacterial cells was obtained with NIR-irradiation (2.8 W cm^-2, 20 min) after 2 h-incubation. In addition, these nanoheaters modified on spores could be taken not only to the vegetative bacteria cells, but also to the first-generation bacteria cells with their excellent photothermal and bactericidal performance, as well as synergetic anticancer effect. NIR-irradiation after 2 h-incubation could also trigger Spore@NRs/NCs (1:1:4, 6 μL) to synergistically reduce the viability of HCT116 cells to 15.63±2.90%.

Conclusion

By using NIR-irradiation, the "transitive" nanoheaters can remotely control the activity of both bacteria (germinated from spore) and cancer cells. This discovery provides basis and a feasible plan for controllable safer treatment of bacteria therapy, especially anaerobes with spores in hypoxic areas of the malignant solid tumors.

Research progress in inducing immunogenic cell death of tumor cells

Immunogenic cell death (ICD) is a regulated cell death (RCD) pathway. In response to physical and chemical signals, tumor cells activate specific signaling pathways that stimulate stress responses in the endoplasmic reticulum (ER) and expose damage-associated molecular patterns (DAMPs), which promote antitumor immune responses. As a result, the tumor microenvironment is altered, and many tumor cells are killed. The ICD response in tumor cells requires inducers. These inducers can be from different sources and contribute to the development of the ICD either indirectly or directly. The combination of ICD inducers with other tumor treatments further enhances the immune response in tumor cells, and more tumor cells are killed; however, it also produces side effects of varying severity. New induction methods based on nanotechnology improve the antitumor ability and significantly reduces side effects because they can target tumor cells precisely. In this review, we introduce the characteristics and mechanisms of ICD responses in tumor cells and the DAMPs associated with ICD responses, summarize the current methods of inducing ICD response in tumor cells in five distinct categories: chemical sources, physical sources, pathogenic sources, combination therapies, and innovative therapies. At the same time, we introduce the limitations of current ICD inducers and make a summary of the use of ICD responses in clinical trials. Finally, we provide an outlook on the future of ICD inducer development and provide some constructive suggestions.

Magnetothermal Control of Temperature-Sensitive Repressors in Superparamagnetic Iron Nanoparticle-Coated Bacillus subtilis

Superparamagnetic iron oxide nanoparticles (SPIONs) are used as contrast agents in magnetic resonance imaging (MRI) and magnetic particle imaging (MPI), and resulting images can be used to guide magnetothermal heating. Alternating magnetic fields (AMF) cause local temperature increases in regions with SPIONs, and we investigated the ability of magnetic hyperthermia to regulate temperature-sensitive repressors (TSRs) of bacterial transcription. The TSR, TlpA39, was derived from a Gram-negative bacterium and used here for thermal control of reporter gene expression in Gram-positive, Bacillus subtilis. In vitro heating of B. subtilis with TlpA39 controlling bacterial luciferase expression resulted in a 14.6-fold (12 hours; h) and 1.8-fold (1 h) increase in reporter transcripts with a 10.0-fold (12 h) and 12.1-fold (1 h) increase in bioluminescence. To develop magnetothermal control, B. subtilis cells were coated with three SPION variations. Electron microscopy coupled with energy dispersive X-ray spectroscopy revealed an external association with, and retention of, SPIONs on B. subtilis. Furthermore, using long duration AMF we demonstrated magnetothermal induction of the TSRs in SPION-coated B. subtilis with a maximum of 5.6-fold increases in bioluminescence. After intramuscular injections of SPION-coated B. subtilis, histology revealed that SPIONs remained in the same locations as the bacteria. For in vivo studies, 1 h of AMF is the maximum exposure due to anesthesia constraints. Both in vitro and in vivo, there was no change in bioluminescence after 1 h of AMF treatment. Pairing TSRs with magnetothermal energy using SPIONs for localized heating with AMF can lead to transcriptional control that expands options for targeted bacteriotherapies.

Recent advances in bacteria-mediated cancer therapy

Cancer is among the leading cause of deaths worldwide. Although conventional therapies have been applied in the fight against the cancer, the poor oxygen, low extracellular pH, and high interstitial fluid pressure of the tumor microenvironment mean that these treatments fail to completely eradicate cancer cells. Recently, bacteria have increasingly been considered to be a promising platform for cancer therapy thanks to their many unique properties, such as specific tumor-targeting ability, high motility, immunogenicity, and their use as gene or drug carriers. Several types of bacteria have already been used for solid and metastatic tumor therapies, with promising results. With the development of synthetic biology, engineered bacteria have been endowed with the controllable expression of therapeutic proteins. Meanwhile, nanomaterials have been widely used to modify bacteria for targeted drug delivery, photothermal therapy, magnetothermal therapy, and photodynamic therapy, while promoting the antitumor efficiency of synergistic cancer therapies. This review will provide a brief introduction to the foundation of bacterial biotherapy. We begin by summarizing the recent advances in the use of many different types of bacteria in multiple targeted tumor therapies. We will then discuss the future prospects of bacteria-mediated cancer therapies.

Molecular Characterization of CF33 Canine Cell Line and Evaluation of Its Ability to Respond against Infective Stressors in Sight of Anticancer Approaches

Simple Summary

Canine mammary cancer is very common and has many similarities with human breast cancer. Risk factors, physiological and pathological behaviors, and the clinical course in dogs are very similar to humans. Several molecular similarities have also been reported, such as overexpression of EGF, proliferation markers, metalloproteinase and cyclooxygenase, TP53 mutations, and CXCR4/SDF1 axis activation. These common characteristics make these breast tumors resistant to conventional therapies. It is therefore necessary to study therapeutic alternatives. Cell lines could be helpful to test in vitro immunomodulant anti-cancer therapies, allowing a reduction of laboratory animals’ involvement in the preliminary tests and achieving results in a shorter time. Although the canine mammary carcinoma cell line CF33 has been widely used in many studies on dog mammary cancer, characterization of its gene expression profile and of the influence of infective stressors of this cell line is poor. Our study shows the interaction of CF33 and Salmonella Typhimurium (ST) as an infective stressor, indicating that these cells may represent an in vitro model for assessing novel therapeutic approaches using bacteria.

Abstract

Spontaneous mammary tumors are the most frequent neoplasms in bitches and show similarities with human breast cancer in risk factors, clinical course, and histopathology. The poor prognosis of some cancer subtypes, both in human and dog, demands more effective therapeutic approaches. A possible strategy is the new anticancer therapy based on immune response modulation through bacteria or their derivatives on canine mammary carcinoma cell lines. The aim of the present study was to analyze the CF33 cell line in terms of basal expression of immune innate genes, CXCR4 expression, and interaction with infectious stressors. Our results highlight that CF33 maintains gene expression parameters typical of mammary cancer, and provides the basal gene expression of CF33, which is characterized by overexpression of CXCR4, CD44, RAD51, LY96, and a non-continuous expression of TP53 and PTEN. No mutations appeared in the CXCR4 gene until the 58th passage; this may represent important information for studying the CXCR4 pathway as a therapeutic target. Moreover, the CF33 cell line was shown to be able to interact with Salmonella Typhimurium (ST) (an infective stressor), indicating that these cells could be used as an in vitro model for developing innovative therapeutic approaches involving bacteria.

Cancer Stem Cells and the Tumor Microenvironment: Targeting the Critical Crosstalk through Nanocarrier Systems

The physiological state of the tumor microenvironment (TME) plays a central role in cancer development due to multiple universal features that transcend heterogeneity and niche specifications, like promoting cancer progression and metastasis. As a result of their preponderant involvement in tumor growth and maintenance through several microsystemic alterations, including hypoxia, oxidative stress, and acidosis, TMEs make for ideal targets in both diagnostic and therapeutic ventures. Correspondingly, methodologies to target TMEs have been investigated this past decade as stratagems of significant potential in the genre of focused cancer treatment. Within targeted oncotherapy, nanomedical derivates-nanocarriers (NCs) especially-have emerged to present notable prospects in enhancing targeting specificity. Yet, one major issue in the application of NCs in microenvironmental directed therapy is that TMEs are too broad a spectrum of targeting possibilities for these carriers to be effectively employed. However, cancer stem cells (CSCs) might portend a solution to the above conundrum: aside from being quite heavily invested in tumorigenesis and therapeutic resistance, CSCs also show self-renewal and fluid clonogenic properties that often define specific TME niches. Further scrutiny of the relationship between CSCs and TMEs also points towards mechanisms that underly tumoral characteristics of metastasis, malignancy, and even resistance. This review summarizes recent advances in NC-enabled targeting of CSCs for more holistic strikes against TMEs and discusses both the current challenges that hinder the clinical application of these strategies as well as the avenues that can further CSC-targeting initiatives. Central role of CSCs in regulation of cellular components within the TME.

Engineered endosymbionts that alter mammalian cell surface marker, cytokine and chemokine expression

Developing modular tools that direct mammalian cell function and activity through controlled delivery of essential regulators would improve methods of guiding tissue regeneration, enhancing cellular-based therapeutics and modulating immune responses. To address this challenge, Bacillus subtilis was developed as a chassis organism for engineered endosymbionts (EES) that escape phagosome destruction, reside in the cytoplasm of mammalian cells, and secrete proteins that are transported to the nucleus to impact host cell response and function. Two synthetic operons encoding either the mammalian transcription factors Stat-1 and Klf6 or Klf4 and Gata-3 were recombined into the genome of B. subtilis expressing listeriolysin O (LLO) from Listeria monocytogenes and expressed from regulated promoters. Controlled expression of the mammalian proteins from B. subtilis LLO in the cytoplasm of J774A.1 macrophage/monocyte cells altered surface marker, cytokine and chemokine expression. Modulation of host cell fates displayed some expected patterns towards anti- or pro-inflammatory phenotypes by each of the distinct transcription factor pairs with further demonstration of complex regulation caused by a combination of the EES interaction and transcription factors. Expressing mammalian transcription factors from engineered intracellular B. subtilis as engineered endosymbionts comprises a new tool for directing host cell gene expression for therapeutic and research purposes.

The establishment of non-pathogenic engineered endosymbionts through B. subtilis is presented, with the aim of delivering mammalian transcription factors to the host cell for therapeutics and research.

Modulating Microbiota as a New Strategy for Breast Cancer Prevention and Treatment

Breast cancer (BC) is the most common cancer in women in the United States. There has been an increasing incidence and decreasing mortality rate of BC cases over the past several decades. Many risk factors are associated with BC, such as diet, aging, personal and family history, obesity, and some environmental factors. Recent studies have shown that healthy individuals and BC patients have different microbiota composition, indicating that microbiome is a new risk factor for BC. Gut and breast microbiota alterations are associated with BC prognosis. This review will evaluate altered microbiota populations in gut, breast tissue, and milk of BC patients, as well as mechanisms of interactions between microbiota modulation and BC. Probiotics and prebiotics are commercially available dietary supplements to alleviate side-effects of cancer therapies. They also shape the population of human gut microbiome. This review evaluates novel means of modulating microbiota by nutritional treatment with probiotics and prebiotics as emerging and promising strategies for prevention and treatment of BC. The mechanistic role of probiotic and prebiotics partially depend on alterations in estrogen metabolism, systematic immune regulation, and epigenetics regulation.

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.

Marine biome-derived secondary metabolites, a class of promising antineoplastic agents: A systematic review on their classification, mechanism of action and future perspectives

Cancer is one of the most deadly diseases on the planet. Over the past decades, numerous antineoplastic compounds have been discovered from natural resources such as medicinal plants and marine species as part of multiple drug discovery initiatives. Notably, several marine flora (e.g. Ascophyllum nodosum, Sargassum thunbergii) have been identified as a rich source for novel cytotoxic compounds of different chemical forms. Despite the availability of enormous chemically enhanced new resources, the anticancer potential of marine flora and fauna has received little attention. Interestingly, numerous marine-derived secondary metabolites (e.g., Cytarabine, Trabectedin) have exhibited anticancer effects in preclinical cancer models. Most of the anticancer drugs obtained from marine sources stimulated apoptotic signal transduction pathways in cancer cells, such as the intrinsic and extrinsic pathways. This review highlights the sources of different cytotoxic secondary metabolites obtained from marine bacteria, algae, fungi, invertebrates, and vertebrates. Furthermore, this review provides a comprehensive overview of the utilisation of numerous marine-derived cytotoxic compounds as anticancer drugs, as well as their modes of action (e.g., molecular target). Finally, it also discusses the future prospects of marine-derived drug developments and their constraints.

Structure-Activity Relationship of the Dimeric and Oligomeric Forms of a Cytotoxic Biotherapeutic Based on Diphtheria Toxin

Protein aggregation is a well-recognized problem in industrial preparation, including biotherapeutics. These low-energy states constantly compete with a native-like conformation, which is more pronounced in the case of macromolecules of low stability in the solution. A better understanding of the structure and function of such aggregates is generally required for the more rational development of therapeutic proteins, including single-chain fusion cytotoxins to target specific receptors on cancer cells. Here, we identified and purified such particles as side products of the renaturation process of the single-chain fusion cytotoxin, composed of two diphtheria toxin (DT) domains and interleukin 13 (IL-13), and applied various experimental techniques to comprehensively understand their molecular architecture and function. Importantly, we distinguished soluble purified dimeric and fractionated oligomeric particles from aggregates. The oligomers are polydisperse and multimodal, with a distribution favoring lower and even stoichiometries, suggesting they are composed of dimeric building units. Importantly, all these oligomeric particles and the monomer are cystine-dependent as their innate disulfide bonds have structural and functional roles. Their reduction triggers aggregation. Presumably the dimer and lower oligomers represent the metastable state, retaining the native disulfide bond. Although significantly reduced in contrast to the monomer, they preserve some fraction of bioactivity, manifested by their IL-13RA2 receptor affinity and selective cytotoxic potency towards the U-251 glioblastoma cell line. These molecular assemblies probably preserve structural integrity and native-like fold, at least to some extent. As our study demonstrated, the dimeric and oligomeric cytotoxin may be an exciting model protein, introducing a new understanding of its monomeric counterpart’s molecular characteristics.

Role of Fungal Infections in Carcinogenesis and Cancer Development: A Literature Review

Cancer is a serious debilitating disease and one of the most common causes of death. In recent decades the high risk of various cancers enforced scientists to discover novel prevention and treatment methods to diminish the mortality of this terrifying disease. Accordingly, its prevention can be possible in near future. Based on epidemiological evidence, there is a clear link between pathogenic fungal infections and cancer development. This association is often seen in people with weakened immune systems such as the elderly and people with acquired immunodeficiency (AIDS). Carcinoma in these people is first seen chronically and then acutely. Although the different genetic and environmental risk factors are involved in carcinogenesis, one of the most important risk factors is fungal species and infections associating with cancers etiology. Now it is known that microbial infection is responsible for initiating 2.2 million new cancer cases. In this way, many recent studies have focused on investigating the role and mechanism of fungal infections in diverse cancers occurrence. This review provides a comprehensive framework of the latest clinical findings and the association of fungal infections with versatile cancers including esophageal, gastric, colorectal, lung, cervical, skin, and ovarian cancer.

A Perspective on Studies of Phage DNA Packaging Dynamics

The Special Issue “DNA Packaging Dynamics of Bacteriophages” is focused on an event that is among the physically simplest known events with biological character. Thus, phage DNA (and RNA) packaging is used as a relatively accessible model for physical analysis of all biological events. A similar perspective motivated early phage-directed work, which was a major contributor to early molecular biology. However, analysis of DNA packaging encounters the limitation that phages vary in difficulty of observing various aspects of their packaging. If a difficult-to-access aspect arises while using a well-studied phage, a counterstrategy is to (1) look for and use phages that provide a better access “window” and (2) integrate multi-phage-accessed information with the help of chemistry and physics. The assumption is that all phages are characterized by the same evolution-derived themes, although with variations. Universal principles will emerge from the themes. A spin-off of using this strategy is the isolation and characterization of the diverse phages needed for biomedicine. Below, I give examples in the areas of infectious disease, cancer, and neurodegenerative disease.

Indispensable role of microbes in anticancer drugs and discovery trends

Recent years have seen an increased focus on the advancement of naturally derived products for the treatment of cancer. Since the beginning of recorded history, nature has provided a variety of medicinal agents, and an overwhelming number of drugs that we have today are derived from natural sources. Such natural agents are prominently used to treat several diseases such as diabetes, malaria, Alzheimer's, pulmonary disorders, etc. with cancer being the highlight of this review. Due to the rapid development of resistance to chemotherapeutic drugs, the hunt for effective novel drugs is still a paramount concern in cancer treatment. Moreover, many chemotherapy drugs typically have high toxicity and adverse side effects, which necessitates the need to develop anti-tumor drugs that can be employed to treat deadly tumors with fewer negative effects on health and better efficacy. Isolation of several chemotherapeutic drugs has been conducted from a wide range of natural sources which include plants, microbes, fungi, and marine microorganisms. Considering the trends of previous decades, microbial diversity has grown to play a significant role in the formulation of pharmaceuticals and drugs, especially antibiotics and anti-cancer medications. Microbe-derived antitumor antibiotics such as anthracycline, epothilones, bleomycin, actinomycin, and staurosporine are amongst the widely used cancer chemotherapeutic agents. This review deals majorly with microbe-derived anticancer drugs taking into account their derivatives, mechanism of action, isolation procedures, limitations, and tumors targeted by them. This article also reports the phase of clinical study these drugs are undergoing. Moreover, it intends to portray the indispensable part that these microbes have been playing since time immemorial in the odyssey of chemotherapeutic agents. KEY POINTS: • Microbial diversity contributes heavily towards the formulation of anticancer drugs. • Polypeptides, carbohydrates, and alkaloids are prevalent microbe-based drug classes. • Microbe-derived anticancer agents target various sarcomas, carcinomas, and lymphomas.

Engineered Bacteria with Genetic Circuits Accumulating Nanomagnets as MRI Contrast Agents

The demand for highly efficient cancer diagnostic tools increases alongside the high cancer incidence nowadays. Moreover, there is an imperative need for novel cancer treatment therapies that lack the side effects of conventional treatment options. Developments in this aspect employ magnetic nanoparticles (MNPs) for biomedical applications due to their stability, biocompatibility, and magnetic properties. Certain organisms, including many bacteria, can synthesize magnetic nanocrystals, which help their spatial orientation and survival by sensing the earth's geomagnetic field. This work aims to convert Escherichia coli to accumulate magnetite, which can further be coupled with drug delivery modules. The authors design magnetite accumulating bacterial machines using genetic circuitries hiring Mms6 with iron-binding activity and essential in magnetite crystal formation. The work demonstrates that the combinatorial effect of Mms6 with ferroxidase, iron transporter protein, and material binding peptide enhances the paramagnetic behavior of the cells in magnetic resonance imaging (MRI) measurements. Cellular machines are also engineered to display Mms6 peptide on the cell surface via an autotransporter protein that shows augmented MRI performance. The findings are promising for endowing a probiotic bacterium, able to accumulate magnetite intracellularly or extracellularly, serving as a theranostics agent for cancer diagnostics via MRI scanning and hyperthermia treatment.

Magnetic Particle Imaging of Magnetotactic Bacteria as Living Contrast Agents Is Improved by Altering Magnetosome Arrangement

Superparamagnetic iron oxide nanoparticles (SPIONs) can be used as imaging agents to differentiate between normal and diseased tissue or track cell movement. Magnetic particle imaging (MPI) detects the magnetic properties of SPIONs, providing quantitative and sensitive image data. MPI performance depends on the size, structure, and composition of nanoparticles. Magnetotactic bacteria produce magnetosomes with properties similar to those of synthetic nanoparticles, and these can be modified by mutating biosynthetic genes. The use of Magnetospirillum gryphiswaldense, MSR-1 with a mamJ deletion, containing clustered magnetosomes instead of typical linear chains, resulted in improved MPI signal and resolution. Bioluminescent MSR-1 with the mamJ deletion were administered into tumor-bearing and healthy mice. In vivo bioluminescence imaging revealed the viability of MSR-1, and MPI detected signals in livers and tumors. The development of living contrast agents offers opportunities for imaging and therapy with multimodality imaging guiding development of these agents by tracking the location, viability, and resulting biological effects.

Bacterial-Based Methods for Cancer Treatment: What We Know and Where We Are

A severe disease, cancer is caused by the exponential and uncontrolled growth of cells, leading to organ dysfunction as well as disorders. This disease has been recognized as one of the significant challenges to health and medicine. Various treatment procedures for cancer are associated with diverse side effects; the most conventional cancer treatments include chemotherapy, surgery, and radiotherapy, among others. Numerous adverse and side effects, low specificity and sensitivity, narrow therapeutic windows, and, recently, the emergence of tumor cells resistant to such treatments have been documented as the shortcomings of conventional treatment strategies. As a group of prokaryotic microorganisms, bacteria have great potential for use in cancer therapy. Currently, utilizing bacteria for cancer treatment has attracted the attention of scientists. The high potential of bacteria to become non-pathogenic by genetic manipulation, their distinguished virulence factors (which can be used as weapons against tumors), their ability to proliferate in tissues, and the contingency to control their population by administrating antibiotics, etc., have made bacteria viable candidates and live micro-medication for cancer therapies. However, the possible cytotoxicity impacts of bacteria, their inability to entirely lyse cancerous cells, as well as the probability of mutations in their genomes are among the significant challenges of bacteria-based methods for cancer treatment. In this article, various available data on bacterial therapeutics, along with their pros and cons, are discussed.

Predicting cancer prognosis and drug response from the tumor microbiome

Tumor gene expression is predictive of patient prognosis in some cancers. However, RNA-seq and whole genome sequencing data contain not only reads from host tumor and normal tissue, but also reads from the tumor microbiome, which can be used to infer the microbial abundances in each tumor. Here, we show that tumor microbial abundances, alone or in combination with tumor gene expression, can predict cancer prognosis and drug response to some extent-microbial abundances are significantly less predictive of prognosis than gene expression, although similarly as predictive of drug response, but in mostly different cancer-drug combinations. Thus, it appears possible to leverage existing sequencing technology, or develop new protocols, to obtain more non-redundant information about prognosis and drug response from RNA-seq and whole genome sequencing experiments than could be obtained from tumor gene expression or genomic data alone.

Pseudomonas aeruginosa in Cancer Therapy: Current Knowledge, Challenges and Future Perspectives

Drug resistance, undesirable toxicity and lack of selectivity are the major challenges of conventional cancer therapies, which cause poor clinical outcomes and high mortality in many cancer patients. Development of alternative cancer therapeutics are highly required for the patients who are resistant to the conventional cancer therapies, including radiotherapy and chemotherapy. The success of a new cancer therapy depends on its high specificity to cancer cells and low toxicity to normal cells. Utilization of bacteria has emerged as a promising strategy for cancer treatment. Attenuated or genetically modified bacteria were used to inhibit tumor growth, modulate host immunity, or deliver anti-tumor agents. The bacteria-derived immunotoxins were capable of destructing tumors with high specificity. These bacteria-based strategies for cancer treatment have shown potent anti-tumor effects both in vivo and in vitro, and some of them have proceeded to clinical trials. Pseudomonas aeruginosa, a Gram-negative bacterial pathogen, is one of the common bacteria used in development of bacteria-based cancer therapy, particularly known for the Pseudomonas exotoxin A-based immunotoxins, which have shown remarkable anti-tumor efficacy and specificity. This review concisely summarizes the current knowledge regarding the utilization of P. aeruginosa in cancer treatment, and discusses the challenges and future perspectives of the P. aeruginosa-based therapeutic strategies.

Bacterial infections in cancer: A bilateral relationship

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

Therapeutic Applications of Magnetotactic Bacteria and Magnetosomes: A Review Emphasizing on the Cancer Treatment

Magnetotactic bacteria (MTB) are aquatic microorganisms have the ability to biomineralize magnetosomes, which are membrane-enclosed magnetic nanoparticles. Magnetosomes are organized in a chain inside the MTB, allowing them to align with and traverse along the earth’s magnetic field. Magnetosomes have several potential applications for targeted cancer therapy when isolated from the MTB, including magnetic hyperthermia, localized medication delivery, and tumour monitoring. Magnetosomes features and properties for various applications outperform manufactured magnetic nanoparticles in several ways. Similarly, the entire MTB can be regarded as prospective agents for cancer treatment, thanks to their flagella’s ability to self-propel and the magnetosome chain’s ability to guide them. MTBs are conceptualized as nanobiots that can be guided and manipulated by external magnetic fields and are driven to hypoxic areas, such as tumor sites, while retaining the therapeutic and imaging characteristics of isolated magnetosomes. Furthermore, unlike most bacteria now being studied in clinical trials for cancer treatment, MTB are not pathogenic but might be modified to deliver and express certain cytotoxic chemicals. This review will assess the current and prospects of this burgeoning research field and the major obstacles that must be overcome before MTB can be successfully used in clinical treatments.

Targeting the gut and tumor microbiota in cancer

Microorganisms within the gut and other niches may contribute to carcinogenesis, as well as shaping cancer immunosurveillance and response to immunotherapy. Our understanding of the complex relationship between different host-intrinsic microorganisms, as well as the multifaceted mechanisms by which they influence health and disease, has grown tremendously-hastening development of novel therapeutic strategies that target the microbiota to improve treatment outcomes in cancer. Accordingly, the evaluation of a patient's microbial composition and function and its subsequent targeted modulation represent key elements of future multidisciplinary and precision-medicine approaches. In this Review, we outline the current state of research toward harnessing the microbiome to better prevent and treat cancer.

Recent Update on Bacteria as a Delivery Carrier in Cancer Therapy: From Evil to Allies

Cancer is associated with a comprehensive burden that significantly affects patient’s quality of life. Even though patients’ disease condition is improving following conventional therapies, researchers are studying alternative tools that can penetrate solid tumours to deliver the therapeutics due to issues of developing resistance by the cancer cells. Treating cancer is not the only the goal in cancer therapy; it also includes protecting non-cancerous cells from the toxic effects of anti-cancer agents. Thus, various advanced techniques, such as cell-based drug delivery, bacteria-mediated therapy, and nanoparticles, are devised for site-specific delivery of drugs. One of the novel methods that can be targeted to deliver anti-cancer agents is by utilising genetically modified non-pathogenic bacterial species. This is due to the ability of bacterial species to multiply selectively or non-selectively on tumour cells, resulting in biofilms that leads to disruption of metastasis process. In preclinical studies, this technology has shown significant results in terms of efficacy, and some are currently under investigation. Therefore, researchers have conducted studies on bacteria transporting the anti-cancer drug to targeted tumours. Alternatively, bacterial ghosts and bacterial spores are utilised to deliver anti-cancer drugs. Although in vivo studies of bacteria-mediated cancer therapy have shown successful outcome, further research on bacteria, specifically their targeting mechanism, is required to establish a complete clinical approach in cancer treatment. This review has focused on the up-to-date understanding of bacteria as a therapeutic carrier in the treatment of cancer as an emerging field.

Reprogramming Synthetic Cells for Targeted Cancer Therapy

Advances in synthetic biology enable the reprogramming of bacteria as smart agents to specifically target tumors and locally release anticancer drugs in a highly controlled manner. However, the bench-to-bedside translation of engineered bacteria is often impeded by genetic instability and the potential risk of uncontrollable replication of engineered bacteria inside the patient. SimCells (simple cells) are chromosome-free bacteria controlled by designed gene circuits, which can bypass the interference of the native gene network in bacteria and eliminate the risk of bacterial uncontrolled growth. Here, we describe the reprogramming of SimCells and mini-SimCells to serve as “safe and live drugs” for targeted cancer therapy. We engineer SimCells to display nanobodies on the surface for the binding of carcinoembryonic antigen (CEA), which is an important biomarker found commonly in colorectal cancer cells. We show that SimCells and mini-SimCells with surface display of anti-CEA nanobody can specifically bind CEA-expressing Caco2 cancer cells in vitro while leaving the non-CEA-expressing SW80 cancer cells untouched. These cancer-targeting SimCells and mini-SimCells induced cancer cell death in vitro by compromising the plasma membrane of cancer cells. The cancer-killing effect can be further enhanced by an aspirin/salicylate inducible gene circuit that converts salicylate into catechol, a potent anticancer. This work highlights the potential of SimCells and mini-SimCells for targeted cancer therapy and lays the foundation for the application of synthetic biology to medicine.

Cytolysin A (ClyA): A Bacterial Virulence Factor with Potential Applications in Nanopore Technology, Vaccine Development, and Tumor Therapy

Cytolysin A (ClyA) is a pore-forming toxin that is produced by some bacteria from the Enterobacteriaceae family. This review provides an overview of the current state of knowledge regarding ClyA, including the prevalence of the encoding gene and its transcriptional regulation, the secretion pathway used by the protein, and the mechanism of protein assembly, and highlights potential applications of ClyA in biotechnology. ClyA expression is regulated at the transcriptional level, primarily in response to environmental stressors, and ClyA can exist stably both as a soluble monomer and as an oligomeric membrane complex. At high concentrations, ClyA induces cytolysis, whereas at low concentrations ClyA can affect intracellular signaling. ClyA is secreted in outer membrane vesicles (OMVs), which has important implications for biotechnology applications. For example, the native pore-forming ability of ClyA suggests that it could be used as a component of nanopore-based technologies, such as sequencing platforms. ClyA has also been exploited in vaccine development owing to its ability to present antigens on the OMV surface and provoke a robust immune response. In addition, ClyA alone or OMVs carrying ClyA fusion proteins have been investigated for their potential use as anti-tumor agents.

Yeast-derived nanoparticles remodel the immunosuppressive microenvironment in tumor and tumor-draining lymph nodes to suppress tumor growth

Microbe-based cancer immunotherapy has recently emerged as a hot topic for cancer treatment. However, serious limitations remain including infection associated side-effect and unsatisfactory outcomes in clinic trials. Here, we fabricate different sizes of nano-formulations derived from yeast cell wall (YCW NPs) by differential centrifugation. The induction of anticancer immunity of our formulations appears to inversely correlate with their size due to the ability to accumulate in tumor-draining lymph node (TDLN). Moreover, we use a percolation model to explain their distribution behavior toward TDLN. The abundance and functional orientation of each effector component are significantly improved not only in the microenvironment in tumor but also in the TDLN following small size YCW NPs treatment. In combination with programmed death-ligand 1 (PD-L1) blockade, we demonstrate anticancer efficiency in melanoma-challenged mice. We delineate potential strategy to target immunosuppressive microenvironment by microbe-based nanoparticles and highlight the role of size effect in microbe-based immune therapeutics.

Components of the yeast cell wall, including but not limited to β-glucan, have been reported to act as danger signals and promote immune responses. Here the authors report the design and anti-tumor immune responses elicited by yeast cell wall-based nanoparticles in preclinical cancer models.

L-asparaginase mediated therapy in L-asparagine auxotrophic cancers: A review

Microbial L-asparaginase is the most effective first-line therapeutic used in the treatment protocols of paediatric and adult leukemia. Leukemic cell's auxotrophy for L-asparagine is exploited as a therapeutic strategy to mediate cell death through metabolic blockade of L-asparagine using L-asparaginase. Escherichia coli and Erwinia chrysanthemi serve as the major enzyme deriving sources accepted in clinical practise and the enzyme has bestowed improvements in patient outcomes over the last 40 years. However, an array of side effects generated by the native enzymes due to glutamine co-catalysis and short serum stays augmenting frequent dosages, intended a therapeutic switch towards the development of biobetter alternatives for the enzyme including the formulations resulting in sustained local depletion of L-asparagine. In addition, the treatment with L-asparaginase in few cancer types has proven to elicit drug-induced cytoprotective autophagy mechanisms and therefore warrants concern. Although the off-target glutamine hydrolysis has been viewed in contributing the drug-induced secondary responses in cells deficient with asparagine synthetase machinery, the beneficial role of glutaminase-asparaginase in proliferative regulation of asparagine prototrophic cells has been looked forward. The current review provides an overview on the enzyme's clinical applications in leukemia and possible therapeutic implications in other solid tumours, recent advancements in drug formulations, and discusses the aspects of two-sided roles of glutaminase-asparaginases and drug-induced cytoprotective autophagy mechanisms.

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.

A geometric criterion for the optimal spreading of active polymers in porous media

Efficient navigation through disordered, porous environments poses a major challenge for swimming microorganisms and future synthetic cargo-carriers. We perform Brownian dynamics simulations of active stiff polymers undergoing run-reverse dynamics, and so mimic bacterial swimming, in porous media. In accord with experiments of Escherichia coli, the polymer dynamics are characterized by trapping phases interrupted by directed hopping motion through the pores. Our findings show that the spreading of active agents in porous media can be optimized by tuning their run lengths, which we rationalize using a coarse-grained model. More significantly, we discover a geometric criterion for the optimal spreading, which emerges when their run lengths are comparable to the longest straight path available in the porous medium. Our criterion unifies results for porous media with disparate pore sizes and shapes and for run-and-tumble polymers. It thus provides a fundamental principle for optimal transport of active agents in densely-packed biological and environmental settings.

Paired 18F-Fluorodeoxyglucose (18F-FDG), and 64Cu-Copper(II)-diacetyl-bis(N(4)-methylthiosemicarbazone) (64Cu-ATSM) PET Scans in Dogs with Spontaneous Tumors and Evaluation for Hypoxia-Directed Therapy

Hypoxia is associated with neoplastic tissue, protecting cancer cells from death by irradiation and chemotherapy. Identification of hypoxic volume of tumors could optimize patient selection for hypoxia-directed medical, immunological, and radiation therapies. Clostridium novyi-NT (CNV-NT) is an oncolytic bacterium derived from attenuated wild-type Clostridium novyi spores, which germinates exclusively in the anaerobic core of tumors with low-oxygen content. The hypothesis was that 64Cu-ATSM would localize to regions of hypoxia, and that greater hypoxic volume would result in greater germination of Clostridium novyi-NT (CNV-NT). Tumor-bearing companion dogs were recruited to a veterinary clinical trial. Dogs received a CT scan, 18F-FDG PET scan (74 MBq) and 64Cu-ATSM PET scan (74 MBq). Scan regions of interest were defined as the highest 20% of counts/voxel for each PET scan, and regions with voxels overlapping between the two scans. Maximum standardized uptake value (MaxSUV) and threshold volume were calculated. Direct oximetry was performed in select tumors. Tumor types evaluated included nerve sheath tumor (10), apocrine carcinoma (1), melanoma (3) and oral sarcoma (6). MaxSUVATSM ranged from 0.3-6.6. Measured oxygen tension ranged from 0.05-89.9 mmHg. Inverse of MaxSUVATSM had a linear relationship with oxygen tension (R2 = 0.53, P = 0.0048). Hypoxia <8 mmHg was associated with an SUVATSM > 1.0. Hypoxic volume ranged from 0 to 100% of gross tumor volume (GTV) and MaxSUVATSM was positively correlated with hypoxic volume (R = 0.674; P = 0.0001), but not GTV (P = 0.182). Tumor hypoxic volume was heterogeneous in location and distribution. 64Cu-ATSM-avid regions were associated with differential CT attenuation. Hypoxic volume did not predict CNV-NT germination. 64Cu-ATSM PET scanning predicts hypoxia patterns within spontaneously occurring tumors of dogs as measured by direct oxymetry. Total tumor volume does not accurately predict degree or proportion of tumor hypoxia.

The role played by bacterial infections in the onset and metastasis of cancer

Understanding various responses of cells towards change in their external environment, presence of other species and is important in identifying and correlating the mechanisms leading to malignant transformations and cancer development. Although uncovering and comprehending the association between bacteria and cancer is highly challenging, it promises excellent perspectives and approaches for successful cancer therapy. This review introduces various bacterial species, their virulence factors, and their role in cell transformations leading to cancer (particularly gastric, oral, colon, and breast cancer). Bacterial dysbiosis permutates host cells, causes inflammation, and results in tumorigenesis. This review explored bacterial-mediated host cell transformation causing chronic inflammation, immune receptor hyperactivation/absconding immune recognition, and genomic instability. Bacterial infections downregulate E-cadherin, leading to loosening of epithelial tight junction polarity and triggers metastasis. In addition to understanding the role of bacterial infections in cancer development, we have also reviewed the application of bacteria for cancer therapy. The emergence of bacteriotherapy combined with conventional therapies led to new and effective ways of overcoming challenges associated with available treatments. This review discusses the application of bacterial minicells, microswimmers, and outer cell membrane vesicles (OMV) for drug delivery applications.

Bacteria-Based Live Vehicle for In Vivo Bioluminescence Imaging

The anticancer therapy strategy mediated by tumor-targeting bacteria needs better visualization tools for imaging and monitoring bacteria in vivo. The probiotic strain Escherichia coli Nissle 1917 (EcN), one of the tumor-targeting bacteria, leads to the potential application for cancer therapy. Here, we report the development and application of a live, EcN-based imageable vehicle for noninvasive in vivo bioluminescence imaging in live mice. Firefly luciferase (Fluc) and luciferin-regenerating enzyme (LRE), an enzyme that contributes to stable bioluminescence, were functionally coexpressed in EcN. The recombinant EcN strain expressing the genomically integrated Fluc-LRE cassette was demonstrated to be a valuable tool for generating robust, continuous, and red-shifted bioluminescence for bacterial tracking in vitro and in vivo, thus providing an optical tumor-targeting system for the in vivo study of bacteria-assisted cancer therapy. Additionally, in vivo imaging of the recombinant EcN strain in the mouse intestinal tract indicated the potential of this strain to be used as a tool in the study of gut.

Fighting Cancer with Bacteria and Their Toxins

Cancer is one of the most important global health problems that continues to demand new treatment strategies. Many bacteria that cause persistent infections play a role in carcinogenesis. However, since bacteria are well studied in terms of molecular mechanisms, they have been proposed as an interesting solution to treat cancer. In this review, we present the use of bacteria, and particularly bacterial toxins, in cancer therapy, highlighting the advantages and limitations of bacterial toxins. Proteomics, as one of the omics disciplines, is essential for the study of bacterial toxins. Advances in proteomics have contributed to better characterization of bacterial toxins, but also to the development of anticancer drugs based on bacterial toxins. In addition, we highlight the current state of knowledge in the rapidly developing field of bacterial extracellular vesicles, with a focus on their recent application as immunotherapeutic agents.

The gastrointestinal microbiota in colorectal cancer cell migration and invasion

Colorectal carcinoma is the third most common cancer in developed countries and the second leading cause of cancer-related mortality. Interest in the influence of the intestinal microbiota on CRC emerged rapidly in the past few years, and the close presence of microbiota to the tumour mass creates a unique microenvironment in CRC. The gastrointestinal microbiota secrete factors that can contribute to CRC metastasis by influencing, for example, epithelial-to-mesenchymal transition. Although the role of EMT in metastasis is well-studied, mechanisms by which gastrointestinal microbiota contribute to the progression of CRC remain poorly understood. In this review, we will explore bacterial factors that contribute to the migration and invasion of colorectal carcinoma and the mechanisms involved. Bacteria involved in the induction of metastasis in primary CRC include Fusobacterium nucleatum, Enterococcus faecalis, enterotoxigenic Bacteroides fragilis, Escherichia coli and Salmonella enterica. Examples of prominent bacterial factors secreted by these bacteria include Fusobacterium adhesin A and Bacteroides fragilis Toxin. Most of these factors induce EMT-like properties in carcinoma cells and, as such, contribute to disease progression by affecting cell-cell adhesion, breakdown of the extracellular matrix and reorganisation of the cytoskeleton. It is of utmost importance to elucidate how bacterial factors promote CRC recurrence and metastasis to increase patient survival. So far, mainly animal models have been used to demonstrate this interplay between the host and microbiota. More human-based models are needed to study the mechanisms that promote migration and invasion and mimic the progression and recurrence of CRC.

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.

Interaction of Gut Microbiome and Host microRNAs with the Occurrence of Colorectal and Breast Cancer and Their Impact on Patient Immunity

Breast and colorectal cancers are two primary malignancies on which most of the research done worldwide investigates the potential genetic and environmental risk factors and thereby tries to develop therapeutic methods to improve prognosis. Breast cancer is the most diagnosed cancer type in women, while colorectal cancer is diagnosed in males as the third most and females as the second most cancer type. Though these two cancer types are predominantly seen in adult patients worldwide, in the current context, these malignancies are diagnosed at a younger age with a significant rate of incidents than previous. Such early-onset cancers are generally present at an advanced stage of the most aggressive type with a poor prognosis. In the past, the focus of the research was mainly on studying possible candidate genes to understand the onset. However, it is now recognized that genetics, epigenetics, and other environmental factors play a pivotal role in cancer susceptibility. Thus, most studies were diversified to study the behavior of host microRNAs, and the involvement of gut microbiota and good communication between them surfaced in the occurrence and state of the disease. It is understood that the impact of these factors affects the outcome of the disease. Out of the adverse outcomes identified relating to the disease, immunosuppression is one of the most concerning outcomes in the current world, where such individuals remain vulnerable to infections. Recent studies revealed that microbiome and microRNA could create a considerable impact on immunosuppression. This review focused on the behavior of host microRNAs and gut microbiome for the onset of the disease and progression, thereby influencing an individual's immunosuppression. Understanding the interactions among microRNA, microbiome, presentation of the disease, and impact on the immune system will be immensely useful for developing future therapeutic strategies based on targeting host microRNA and the patient's gut microbiome. Therapies such as inhibitory-miRNA therapies, miRNA mimic-based therapeutics, immune checkpoint blockade therapies, and bacteria-assisted tumor-targeted therapies help modulate cancer. At the same time, it paid equal attention to potential noninvasive biomarkers in diagnosis, prognosis, and therapeutics in both cancers.

Simple and effective bacterial-based intratumoral cancer immunotherapy

BACKGROUND

We describe intratumoral injection of a slow-release emulsion of killed mycobacteria (complete Freund's adjuvant (CFA)) in three preclinical species and in human cancer patients.

METHODS

Efficacy and safety were tested in mammary tumors in mice, in mastocytomas in mice and dogs, and in equine melanomas. In mice, survival, tumor growth, and tumor infiltration by six immune cell subsets (by flow cytometry) were investigated and analyzed using Cox proportional hazards, a random slopes model, and a full factorial model, respectively. Tumor growth and histology were investigated in dogs and horses, as well as survival and tumor immunohistochemistry in dogs. Tumor biopsies were taken from human cancer patients on day 5 (all patients) and day 28 (some patients) of treatment and analyzed by histology. CT scans are provided from one patient.

RESULTS

Significantly extended survival was observed in mouse P815 and 4T1 tumor models. Complete tumor regressions were observed in all three non-human species (6/186 (3%) of mouse mastocytomas; 3/14 (21%) of canine mastocytomas and 2/11 (18%) of equine melanomas). Evidence of systemic immune responses (regression of non-injected metastases) was also observed. Analysis of immune cells infiltrating mastocytoma tumors in mice showed that early neutrophil infiltration was predictive of treatment benefit. Analysis of the site of mastocytoma regression in dogs weeks or months after treatment demonstrated increased B and T cell infiltrates. Thus, activation of the innate immune system alone may be sufficient for regression of some injected tumors, followed by activation of the acquired immune system which can mediate regression of non-injected metastases. Finally, we report on the use of CFA in 12 human cancer patients. Treatment was well tolerated. CT scans showing tumor regression in a patient with late-stage renal cancer are provided.

CONCLUSION

Our data demonstrate that intratumoral injection of CFA has major antitumor effects in a proportion of treated animals and is safe for use in human cancer patients. Further trials in human cancer patients are therefore warranted. Our novel treatment provides a simple and inexpensive cancer immunotherapy, immediately applicable to a wide range of solid tumors, and is suitable to patients in developing countries and advanced care settings.

The oncolytic activity of Clostridium novyi nontoxic spores in breast cancer

Introduction: Hypoxia context is highly specific for tumors and represents a unique niche which is not found elsewhere in the body. Clostridium novyi is an obligate anaerobic bacterium. It has a potential to treat tumors. The aim of this study was to produce the C. novyi nontoxic spores and to investigate its oncolytic effect on breast cancer in mice model. Methods: Primarily, the lethal toxin gene in C. novyi type B was removed. Colonies were isolated using PCR testing. To assure the removal of alpha-toxin, plasmid extraction and in vivo assay were conducted. Next, to treat breast cancer model in different sizes of tumors, a single dose of spores of C. novyi nontoxic was tested. Results: The results denoted that C. novyi nontoxic lost lethal toxin and a--ppeared to be safe. For smaller than 1000 mm³ tumors, a single dose of C. novyi nontoxic was able to cure 100% of mice bearing breast tumors. Hence the mice remained free of tumor relapse. Tumors larger than 1000 mm³ were not cured by a single dose- of C. novyi nontoxic treatment. Conclusion: The experiment concluded that the C. novyi nontoxic might be a suitable and safe candidate, a novel therapeutic approach to encounter such hypoxic regions in the center of tumors. Research also showed that bacteriolytic therapy by C. novyi nontoxic could lead to regression in small tumor.

Synthetic Biology Medicine and Bacteria-Based Cancer Therapeutics

Spontaneous tumor regression following bacterial infection has been observed for hundreds of years. These observations along with anecdotal medical findings in 1890s led to the development of Coley's "toxins," consisting of killed Streptococcus pyogenes and Serratia marcescens bacteria, as the first cancer immunotherapy. The use of this approach, however, was not widely accepted at the time especially after the introduction of radiation therapy as a treatment for cancer in the early 1900s. Over the last 30-40 years there has been renewed interest in the use of bacteria to treat human solid tumors. This is based on the observation that various nonpathogenic anaerobic bacteria can infiltrate and replicate within solid tumors when given intravenously. Bacteria tested as potential anticancer agents include the Gram-positive obligate anaerobes Bifidobacterium and Clostridium, as well as the gram-negative facultative anaerobe Salmonella. Recent advances in synthetic biology and clinical success in cancer immunotherapy provide renewed momentum for developing bacteria-based cancer immunotherapy for cancer treatment and should allow greater potential for the development of novel therapeutic approaches for this devastating disease.