Development of chitosan/heparin nanoparticle-encapsulated cytolethal distending toxin for gastric cancer therapy

Extracellular matrix component-derived nanoparticles for drug delivery and tissue engineering

The extracellular matrix (ECM) consists of a complex combination of proteins, proteoglycans, and other biomolecules. ECM-based materials have been demonstrated to have high biocompatibility and bioactivity, which may be harnessed for drug delivery and tissue engineering applications. Herein, nanoparticles incorporating ECM-based materials and their applications in drug delivery and tissue engineering are reviewed. Proteins such as gelatin, collagen, and fibrin as well as glycosaminoglycans including hyaluronic acid, chondroitin sulfate, and heparin have been employed for cancer therapeutic delivery, gene delivery, and wound healing and regenerative medicine. Strategies for modifying and functionalizing these materials with synthetic and natural polymers or to enable stimuli-responsive degradation and drug release have increased the efficacy of these materials and nano-systems. The incorporation and modification of ECM-based materials may be used to drive drug targeting and increase tissue-specific cell differentiation more effectively.

Mucoadhesive carriers for oral drug delivery

Among the various dosage forms, oral medicine has extensive benefits including ease of administration and patients' compliance, over injectable, suppositories, ocular and nasal. Despite of extensive demand and emerging advantages, over 50% of therapeutic molecules are not available in oral form due to their physicochemical properties. More importantly, most of the biologics, proteins, peptide, and large molecular drugs are mostly available in injectable form. Conventional oral drug delivery system has limitation such as degradation and lack of stability within stomach due to presence of highly acidic gastric fluid, hinders their therapeutic efficacy and demand more frequent and higher dosing. Hence, formulation for controlled, sustained, and targeted drug delivery, need to be designed with feasibility to target the specific region of gastrointestinal (GI) tract such as stomach, small intestine, intestine lymphatic, and colon is challenging. Among various oral delivery approaches, mucoadhesive vehicles are promising and has potential for improving oral drug retention and controlled absorption to treat local diseases within the GI tract, as well systemic diseases. This review provides the overview about the challenges and opportunities to design mucoadhesive formulation for oral delivery of therapeutics in a way to target the specific region of the GI tract. Finally, we have concluded with future perspective and potential of mucoadhesive formulations for oral local and systemic delivery.

Cytolethal distending toxin: from genotoxin to a potential biomarker and anti-tumor target

Cytolethal Distending Toxin (CDT) belongs to the AB toxin family and is produced by a plethora of Gram-negative bacteria. Eight human-affecting enteropathogens harbor CDT that causes irritable bowel syndrome (IBS), dysentery, chancroid, and periodontitis worldwide. They have a novel molecular mode of action as they interfere in the eukaryotic cell-cycle progression leading to G₂/M arrest and apoptosis. CDT, the first bacterial genotoxin described, is encoded in a single operon possessing three proteins, CdtA, CdtB, and CdtC. CdtA and CdtC are needed for the binding of the CDT toxin complex to the cholesterol-rich lipid domains of the host cell while the CdtB is the active moiety. Sequence and 3D structural-based analysis of CdtB showed similarities with nucleases and phosphatases, it was hypothesized that CdtB exercises a biochemical function identical to both these enzymes. CDT is secreted through the outer membrane vesicles from the producing bacteria. It is internalized in the target cells via clathrin-dependent endocytosis and translocated to the host cell nucleus through the Golgi complex and ER. This study discusses the virulence role of CDT, causing pathogenicity by acting as a tri-perditious complex in the CDT-producing species with an emphasis on its potential role as a biomarker and an anti-tumor agent.

Molecular targeted treatment and drug delivery system for gastric cancer

Gastric cancer is still a major cancer worldwide. The early diagnosis rate of gastric cancer in most high incidence countries is low. At present, the overall treatment effect of gastric cancer is poor, and the median overall survival remains low. Most of the patients with gastric cancer are in an advanced stage when diagnosed, and drug treatment has become the main means. Thus, new targeted drugs and therapeutic strategies are the hope of improving the therapeutic effect of gastric cancer. In this review, we summarize the new methods and advances of targeted therapy for gastric cancer, including novel molecular targeted therapeutic agents and drug delivery systems, with a major focus on the development of drug delivery systems (drug carriers and targeting peptides). Elaborating these new methods and advances will contribute to the management of gastric cancer.

Bacterial Genotoxin-Coated Nanoparticles for Radiotherapy Sensitization in Prostate Cancer

Prostate cancer (PCa) is one of the most commonly diagnosed cancers in men and usually becomes refractory because of recurrence and metastasis. CD44, a transmembrane glycoprotein, serves as a receptor for hyaluronic acid (HA). It has been found to be abundantly expressed in cancer stem cells (CSCs) that often exhibit a radioresistant phenotype. Cytolethal distending toxin (CDT), produced by Campylobacter jejuni, is a tripartite genotoxin composed of CdtA, CdtB, and CdtC subunits. Among the three, CdtB acts as a type I deoxyribonuclease (DNase I), which creates DNA double-strand breaks (DSBs). Nanoparticles loaded with antitumor drugs and specific ligands that recognize cancerous cell receptors are promising methods to overcome the therapeutic challenges. In this study, HA-decorated nanoparticle-encapsulated CdtB (HA-CdtB-NPs) were prepared and their targeted therapeutic activity in radioresistant PCa cells was evaluated. Our results showed that HA-CdtB-NPs sensitized radioresistant PCa cells by enhancing DSB and causing G2/M cell-cycle arrest, without affecting the normal prostate epithelial cells. HA-CdtB-NPs possess maximum target specificity and delivery efficiency of CdtB into the nucleus and enhance the effect of radiation in radioresistant PCa cells. These findings demonstrate that HA-CdtB-NPs exert target specificity accompanied with radiomimetic activity and can be developed as an effective strategy against radioresistant PCa.

Chitosan: A compound for drug delivery system in gastric cancer-a review

Gastric cancer is known as the fourth most common cancer and the second main cause of cancer-related deaths. Gastric cancer has some characteristics including high incidence rates of metastasis and mortality as well as low rates of early diagnosis, radical resection and 5-year survival. Radical surgery and following chemotherapy has been done for patients with early gastric cancer leading to 90 % survival rate in 5-year after operation. Besides, in advanced stage some cases don't have the chance of surgery as well as the risk of metastasis is high in these patients overally leading to poor prognosis. In recent years, finding a suitable drug delivery system for chemotherapeutic drugs in gastric cancer is an considerable subject for researchers. Chitosan is known as an appropriate compound for chemo-drug delivery in cancer treatment due to its high biodegradability and biocompatibility. Moreover, trans-mucosal drug delivery is facilitated by chitosan via its mucoadhesive and cationic features enhancing interaction with mucous membrane. In addition, a large amount of experimental evidence has reported the efficacy of chitosan for drug delivery in gastric cancer. Thus, the aim of this article was to review this evidence as well as new chitosan-based drug delivery systems investigated in gastric cancer.

Diphtheria Toxin A-Resistant Cell Lines Enable Robust Production and Evaluation of DTA-Encoding Lentiviruses

Suicide genes have been widely investigated for their utility as therapeutic agents and as tools for in vitro negative selection strategies. Several methods for delivery of suicide genes have been explored. Two important considerations for delivery are the quantity of delivered cargo and the ability to target the cargo to specific cells. Delivery using a lentiviral vector is particularly attractive due to the ability to encode the gene within the viral genome, as well as the ability to limit off-target effects by using cell type-specific glycoproteins. Here, we present the design and validation of a diphtheria toxin A (DTA)-encoding lentiviral vector expressing DTA under the control of a constituitive promoter to allow for expression of DTA in a variety of cell types, with specificity provided via selection of glycoproteins for pseudotyping of the lentiviral particles. DTA exerts its toxic activity through inhibition of eukaryotic translation elongation factor 2 (eEF2) via adenosine diphosphate (ADP)-ribosylation of a modified histidine residue, diphthamide, at His715, which blocks protein translation and leads to cell death. Thus, we also detail development of DTA-resistant cell lines, engineered through CRISPR/Cas9-mediated knockout of the diphthamide 1 (DPH1) gene, which enable both robust virus production by transfection and evaluation of DTA-expressing virus infectivity.

Probiotic Lactobacillus spp. act Against Helicobacter pylori-induced Inflammation

The bacterial species, Helicobacter pylori, is associated with several gastrointestinal diseases, and poses serious health threats owing to its resistance to antibiotics. Lactobacillus spp., on the other hand, possess probiotic activities that have beneficial effects in humans. However, the mechanisms by which Lactobacillus spp. harbor favorable functions and act against H. pylori infection remain to be explored. The aim of this study was to investigate the ability of bacterial strains, Lactobacillus rhamnosus and Lactobacillus acidophilus, termed GMNL-74 and GMNL-185, respectively, to inhibit H. pylori growth and inflammation. Our results showed that GMNL-74 and GMNL-185 possess potent antimicrobial activity against multidrug resistant (MDR)-H. pylori. In addition, an in vitro cell-based model revealed that the inhibition of H. pylori adhesion and invasion of gastric epithelial cells and interleukin-8 production were significantly decreased by treatment with both the Lactobacillus strains. In vivo studies demonstrated that colonization of H. pylori and induced inflammation in the mouse stomach were also alleviated by these Lactobacillus strains. Furthermore, the abundance of beneficial gut bacteria, including Bifidobacterium spp. and Akkermansia muciniphilia, were significantly increased in H. pylori-infected mice treated with GMNL-74 and GMNL-185. These results demonstrate that Lactobacillus spp. ameliorate H. pylori-induced inflammation and supports beneficial gut specific bacteria that act against H. pylori infection.

Salmonella-Mediated Cytolethal Distending Toxin Transfer Inhibits Tumor Growth

The Salmonella enterica serovar Choleraesuis (S.C.) has potential as an antitumor agent because of its tumor-targeting characteristics. S.C. can also be used for specific delivery of therapeutic agents and continuous release during replication. Previously, we successfully used S.C. as a vector to transfer a therapeutic gene and oncolytic virus, which suggested that modified S.C. is suitable for incorporating other antitumor agents into a single system. Cytolethal distending toxin B (CdtB) produced by Campylobacter jejuni can induce tumor cell apoptosis. Here we coated CdtB with poly(allylamine hydrochloride) (PAH) to yield PAH-CdtB. Treatment of cells with PAH-coated CdtB induced apoptosis, demonstrating that the compound retained antitumor activity. Furthermore, S.C. coated with PAH-CdtB (CdtB-S.C.) maintained tumor-targeting activity and had an enhanced antitumor effect. Measurement of the cytotoxic effect of CdtB-S.C. in vitro in a tumor cell line showed increased apoptosis whereas treatment of tumor-bearing mice with CdtB-S.C. reduced tumor growth and prolonged survival. Taken together, our results provide evidence that Salmonella carrying CdtB could have application for the treatment of tumors.

Heparin: new life for an old drug

Heparin is one of the oldest drugs, which nevertheless remains in widespread clinical use as an inhibitor of blood coagulation. The history of its identification a century ago unfolded amid one of the most fascinating scientific controversies turning around the distribution of credit for its discovery. The composition, purification and structure-function relationship of this naturally occurring glycosaminoglycan regarding its classical role as anticoagulant will be dealt with before proceeding to discuss its therapeutic potential in, among other, inflammatory and infectious disease, cancer treatment, cystic fibrosis and Alzheimer's disease. The first bibliographic reference hit using the words 'nanomedicine' and 'heparin' is as recent as 2008. Since then, nanomedical applications of heparin have experienced an exponential growth that will be discussed in detail, with particular emphasis on its antimalarial activity. Some of the most intriguing potential applications of heparin nanomedicines will be exposed, such as those contemplating the delivery of drugs to the mosquito stages of malaria parasites.

Sensitization of Radioresistant Prostate Cancer Cells by Resveratrol Isolated from Arachis hypogaea Stems

Resveratrol (RV, 3,4ʹ,5-trihydroxystilbene) is naturally produced by a wide variety of plants including grapes and peanuts (Arachis hypogaea). However, the yield of RV from peanut stem and its potential radiosensitizing effects in prostate cancer (PCa) have not been well investigated. In this study, we characterized RV in peanut stem extract (PSE) for the first time and showed that both RV and PSE dose-dependently induced cell death in DOC-2/DAB2 interactive protein (DAB2IP)-deficient PCa cells with the radioresistant phenotype. Furthermore, the combination of radiation with either RV or PSE induced the death of radioresistant PCa cells through delayed repair of radiation-induced DNA double-strand break (DSB) and prolonged G2/M arrest, which induced apoptosis. The administration of RV and PSE effectively enhanced radiation therapy in the shDAB2IP PCa xenograft mouse model. These results demonstrate the promising synergistic effect of RV and PSE combined with radiation in the treatment of radioresistant PCa.

Molecular Mechanisms and Potential Clinical Applications of Campylobacter jejuni Cytolethal Distending Toxin

Cytolethal distending toxin (CDT), a genotoxin produced by Campylobacter jejuni, is composed of three subunits: CdtA, CdtB, and CdtC. CdtB is a DNase that causes DNA double-strand breaks (DSB) in the nucleus resulting in cell cycle arrest at the G2/M stage and apoptosis. CdtA and CdtC bind to cholesterol-rich microdomains on the cytoplasmic membrane, a process required for the delivery of CdtB to cells. Although a unique motif associated with cholesterol-binding activity has been identified in other pathogens, the mechanism underlying the interaction between the CdtA and CdtC subunits and membrane cholesterol remains unclear. Also, the processes of cell uptake and delivery of CdtB in host cells and the translocation of CdtB into the nucleus are only partially understood. In this review, we focus on the underlying relationship among CDT, membrane cholesterol, and the intracellular trafficking pathway as a unique mechanism for C. jejuni-induced pathogenesis. Moreover, we discuss the clinical aspects of a possible therapeutic application of CDT in cancer therapy. Understanding the molecular mechanism of CDT-host interactions may provide insights into novel strategies to control C. jejuni infection and the development of potential clinical applications of CDT.

Sensitization of radio-resistant prostate cancer cells with a unique cytolethal distending toxin

Cytolethal distending toxin (CDT) produced by Campylobacter jejuni is a genotoxin that induces cell-cycle arrest and apoptosis in mammalian cells. Recent studies have demonstrated that prostate cancer (PCa) cells can acquire radio-resistance when DOC-2/DAB2 interactive protein (DAB2IP) is downregulated. In this study, we showed that CDT could induce cell death in DAB2IP-deficient PCa cells. A combination of CDT and radiotherapy significantly elicited cell death in DAB2IP-deficient PCa cells by inhibiting the repair of ionizing radiation (IR)-induced DNA double-strand break (DSB) during G2/M arrest, which is triggered by ataxia telangiectasia mutated (ATM)-dependent DNA damage checkpoint responses. We also found that CDT administration significantly increased the efficacy of radiotherapy in a xenograft mouse model. These results indicate that CDT can be a potent therapeutic agent for radio-resistant PCa.

Zinc oxide nanoparticles impair bacterial clearance by macrophages

AIM

The extensive development of nanoparticles (NPs) and their widespread employment in daily life have led to an increase in environmental concentrations of substances that may pose a biohazard to humans. The aim of this work was to examine the effects of zinc oxide nanoparticles (ZnO-NPs) on the host's pulmonary immune system response to nontypeable Haemophilus influenzae (NTHi) infection.

MATERIALS & METHODS

A murine infection model was employed to assess pulmonary inflammation and bacterial clearance in response to exposure to ZnO-NPs. The molecular mechanisms underlying ZnO-NP-impaired macrophage activation were investigated.

RESULTS

Treatment with ZnO-NPs impaired macrophage activation, leading to a delay in NTHi clearance in the bronchial alveolar lavage fluids and lungs. Exposure to ZnO-NPs followed by NTHi challenge decreased levels of nitric oxide compared with NTHi infection alone. The effects of ZnO-NPs involved downregulation of NTHi-activated expression of inducible nitric oxide synthase and the translocation of active NF-kB into the nucleus.

CONCLUSION

These results demonstrate that exposure to ZnO-NPs can impair innate immune responses and attenuate macrophage responses to bacterial infection.