Mechanism responsible for the antitumor effect of BCG-CWS using the LEEL method in a mouse bladder cancer model

Bacillus Calmette-Guérin immunotherapy induces an efficient antitumor response to control murine melanoma depending on MyD88 signaling

Bacillus Calmette-Guérin (BCG) is the first line treatment for bladder cancer and it is also proposed for melanoma immunotherapy. BCG modulates the tumor microenvironment (TME) inducing an antitumor effective response, but the immune mechanisms involved still poorly understood. The immune profile of B16-F10 murine melanoma cells was assessed by infecting these cells with BCG or stimulating them with agonists for different innate immune pathways such as TLRs, inflammasome, cGAS-STING and type I IFN. B16-F10 did not respond to any of those stimuli, except for type I IFN agonists, contrasting with bone marrow-derived macrophages (BMDMs) that showed high production of proinflammatory cytokines. Additionally, we confirmed that BCG is able to infect B16-F10, which in turn can activate macrophages and spleen cells from mice in co-culture experiments. Furthermore, we established a subcutaneous B16-F10 melanoma model for intratumoral BCG treatment and compared wild type mice to TLR2-/-, TLR3-/-, TLR4-/-, TLR7-/-, TLR3/7/9-/-, caspase 1-/-, caspase 11-/-, IL-1R-/-, cGAS-/-, STING-/-, IFNAR-/-, MyD88-/-deficient animals. These results in vivo demonstrate that MyD88 signaling is important for BCG immunotherapy to control melanoma in mice. Also, BCG fails to induce cytokine production in the co-culture experiments using B16-F10 and BMDMs or spleen cells derived from MyD88-/- compared to wild-type (WT) animals. Immunotherapy with BCG was not able to induce the recruitment of inflammatory cells in the TME from MyD88-/- mice, impairing tumor control and IFN-γ production by T cells. In conclusion, MyD88 impacts on both innate and adaptive responses to BCG leading to an efficient antitumor response against melanoma.

Innovative System for Delivering Nucleic Acids/Genes Based on Controlled Intracellular Trafficking as Well as Controlled Biodistribution for Nanomedicines

This review paper summarizes progress that has been made in the new field of "Controlled Intracellular Trafficking." This involves the development of new systems for delivering plasmid DNA (pDNA), small interfering RNA (siRNA), mRNA, proteins, their escape from endosomes, the mechanism for how they enter the nucleus, how they enter mithochondria and how materials subsequently function within a cell. In addition, strategies for delivering these materials to a selective tissue after intravenous administration was also intensively investigated not only to the liver but also to tumors, lungs, adipose tissue and the spleen. In 2020, a new mRNA vaccine was developed against coronavirus disease 2019 (COVID-19), where ionizable cationic lipids were used as a delivery system. Our strategy to identify an efficient ionizable cationic lipids (iCL) based on a lipid library as well as their applications concerning the delivery of siRNA/mRNA/pDNA is also described.

State-of-the-Art Advances of Nanomedicine for Diagnosis and Treatment of Bladder Cancer

Bladder cancer is a common malignant tumor of the urinary system. Cystoscopy, urine cytology, and CT are the routine diagnostic methods. However, there are some problems such as low sensitivity and difficulty in staging, which must be urgently supplemented by novel diagnostic methods. Surgery, intravesical instillation, systemic chemotherapy, and radiotherapy are the main clinical treatments for bladder cancer. It is difficult for conventional treatment to deal with tumor recurrence, progression and drug resistance. In addition, the treatment agents usually have the defects of poor specific distribution ability to target tumor tissues and side effects. The rapid development of nanomedicine has brought hope for the treatment of bladder cancer in reducing side effects, enhancing tumor inhibition effects, and anti-drug resistance. Overall, we review the new progression of nano-platforms in the diagnosis and treatment of bladder cancer.

Liposome-Encapsulated Bacillus Calmette-Guérin Cell Wall Skeleton Enhances Antitumor Efficiency for Bladder Cancer In Vitro and In Vivo via Induction of AMP-Activated Protein Kinase

Simple Summary

We engineered novel nanoparticles consisting of liposome-encapsulated Bacillus Calmette–Guérin cell well skeleton (BCG-CWS) for intravesical instillation in bladder cancer. The liposome-encapsulated BCG-CWS nanoparticles had antitumoral effects in an orthotopic bladder cancer mouse model, and the BCG-CWS nanoparticles can be further developed as a non-toxic substitute for live BCG with improved dispensability, stability, and size compatibility. This is significant because we succeeded in the intravesical delivery of BCG-CWS through the intravesical route using a catheter in an orthotopic bladder cancer mouse model to specifically target tumor cells. This is the first study on the BCG-CWS-induced activation of AMPK in urothelial carcinoma cells, suggesting that AMPK-mediated reactive oxygen species (ROS) production and ER stress is a cellular signaling pathway in tumors sensitive to BCG-CWS. These results have the potential for significant ramifications in targeted therapy using a predictive marker for bladder cancer.

Abstract

The Mycobacterium Bacillus Calmette-Guérin cell wall skeleton (BCG-CWS), the main immune active center of BCG, is a potent candidate non-infectious immunotherapeutic drug and an alternative to live BCG for use against urothelial carcinoma. However, its application in anticancer therapy is limited, as BCG-CWS tends to aggregate in both aqueous and non-aqueous solvents. To improve the internalization of BCG-CWS into bladder cancer cells without aggregation, BCG-CWS was nanoparticulated at a 180 nm size in methylene chloride and subsequently encapsulated with conventional liposomes (CWS-Nano-CL) using an emulsified lipid (LEEL) method. In vitro cell proliferation assays showed that CWS-Nano-CL was more effective at suppressing bladder cancer cell growth compared to nonenveloped BCG-CWS. In an orthotopic implantation model of luciferase-tagged MBT2 bladder cancer cells, encapsulated BCG-CWS nanoparticles could enhance the delivery of BCG-CWS into the bladder and suppress tumor growth. Treatment with CWS-Nano-CL induced the inhibition of the mammalian target of rapamycin (mTOR) pathway and the activation of AMP-activated protein kinase (AMPK) phosphorylation, leading to apoptosis, both in vitro and in vivo. Furthermore, the antitumor activity of CWS-Nano-CL was mediated predominantly by reactive oxygen species (ROS) generation and AMPK activation, which induced endoplasmic reticulum (ER) stress, followed by c-Jun N-terminal kinase (JNK) signaling-mediated apoptosis. Therefore, our data suggest that the intravesical instillation of liposome-encapsulated BCG-CWS nanoparticles can facilitate BCG-CW cellular endocytosis and provide a promising drug-delivery system as a therapeutic strategy for BCG-mediated bladder cancer treatment.

Evolution of drug delivery system from viewpoint of controlled intracellular trafficking and selective tissue targeting toward future nanomedicine

Due to the rapid changes that have occurred in the field of drug discovery and the recent developments in the early 21st century, the role of drug delivery systems (DDS) has become increasingly more important. For the past 20 years, our laboratory has been developing gene delivery systems based on lipid-based delivery systems. One of our efforts has been directed toward developing a multifunctional envelope-type nano device (MEND) by modifying the particle surface with octaarginine, which resulted in a remarkably enhanced cellular uptake and improved intracellular trafficking of plasmid DNA (pDNA). When we moved to in vivo applications, however, we were faced with the PEG-dilemma and we shifted our strategy to the incorporation of ionizable cationic lipids into our system. This resulted in some dramatic improvements over our original design and this can be attributed to the development of a new lipid library. We have also developed a mitochondrial targeting system based on a membrane fusion mechanism using a MITO-Porter, which can deliver nucleic acids/pDNA into the matrix of mitochondria. After the appearance of antibody medicines, Opdivo, an immune checkpoint inhibitor, has established cancer immunology as the 4th strategy in cancer therapy. Our DDS technologies can also be applied to this new field of cancer therapy to cure cancer by controlling our immune mechanisms. The latest studies are summarized in this review article.

Distribution of BCG-CWS-Loaded Nanoparticles in the Spleen After Intravenous Injection Affects Cytotoxic T Lymphocyte Activity

Interest has developed in the bacillus Calmette-Guerin (BCG) cell wall skeleton (BCG-CWS) as a noninfectious adjuvant. Although BCG-CWS readily undergoes aggregation, in a previous study, we applied it to cancer immunotherapy via intravenous administration by encapsulating the BCG-CWS into nanoparticles (CWS-NPs). The CWS-NPs were taken up by major histocompatibility complex (MHC) class II⁺ (MHC-II⁺) cells and induced antigen-specific cytotoxic T lymphocyte (CTL) activity. However, the nature of the contribution of MHC-II⁺ cells to the CTL response continues to be unclear. In this study, we investigated the relationship between the distribution of CWS-NPs in the spleen and CTL activity. The main MHC-II⁺ cells that internalized the CWS-NPs were B cells. Decreasing the level of polyethylene glycol modification increased the uptake of CWS-NPs by B cells, leading to an increased CTL activity. A comparison of CWS-NPs with different uptake efficiencies into dendritic cells and B cells suggested that the DCs with internalized CWS-NPs may contribute to CTL activation compared with B cells. We succeeded in enhancing CTL activity by the CWS-NPs, and the findings reported herein should provide important information regarding target cells for the development of CWS-NP.

Enhanced Intracellular Delivery of BCG Cell Wall Skeleton into Bladder Cancer Cells Using Liposomes Functionalized with Folic Acid and Pep-1 Peptide

Although bacillus Calmette–Guérin cell wall skeleton (BCG-CWS) might function as a potential substitute for live BCG, its use in the treatment of bladder cancer remains limited owing to issues such as insolubility and micrometer-size following exposure to an aqueous environment. Thus, to develop a novel nanoparticulate system for efficient BCG-CWS delivery, liposomal encapsulation was carried out using a modified emulsification-solvent evaporation method (targets: Size, <200 nm; encapsulation efficiency, ~60%). Further, the liposomal surface was functionalized with specific ligands, folic acid (FA), and Pep-1 peptide (Pep1), as targeting and cell-penetrating moieties, respectively. Functionalized liposomes greatly increased the intracellular uptake of BCG-CWS in the bladder cancer cell lines, 5637 and MBT2. The immunoactivity was verified through elevated cytokine production and a THP-1 migration assay. In vivo antitumor efficacy revealed that the BCG-CWS-loaded liposomes effectively inhibited tumor growth in mice bearing MBT2 tumors. Dual ligand-functionalized liposome was also superior to single ligand-functionalized liposomes. Immunohistochemistry supported the enhanced antitumor effect of BCG-CWS, with IL-6 production and CD4 infiltration. Thus, we conclude that FA- and Pep1-modified liposomes encapsulating BCG-CWS might be a good candidate for bladder cancer treatment with high target selectivity.

[Development of a Nano DDS for Cancer Immunotherapy Based on Llipid Nanoparticles]

The appearance of immune checkpoint inhibitors has been a major turning point in cancer therapy. The success of immune checkpoint therapy has revolutionized the field of cancer therapy, and immunotherapy has joined the cancer treatment ranks as a pillar. To induce effective anti-tumor immune responses, it is necessary both to enhance the activity of immune cells and to block immune suppression by tumor cells. Carrier type drug delivery systems based on nanobiotechnology (nano DDS) represent a potentially useful technology for efficiently achieving both: enhancement of the activity of immune cells and blocking immune suppression. It has become clear that nano DDS can improve the practical utility of a wide variety of immune functional molecules and thus regulate drug kinetics and intracellular dynamics to improve drug efficacy and reduce side effects. We have been in the process of developing a nano DDS for the enhancement of cancer immunotherapy. A nano DDS encapsulating an agonist of a simulated interferon gene pathway greatly enhanced the activity of the agent's antitumor immune response. To block immune suppression, we successfully developed a small interfering RNA loaded into a nano DDS which regulates gene expression in immune cells. In this review, we summarize our recent efforts regarding cancer immunotherapy using nano DDS.

Application of BCG-CWS as a Systemic Adjuvant by Using Nanoparticulation Technology

The intravesical instillation of live Bacillus Calmette-Guerin (BCG) for treating bladder cancer is a powerful cancer immunotherapy. The BCG cell wall skeleton (BCG-CWS) is the main component of the adjuvant, leading to the induction of antitumor immunity. However, the use of live BCG and BCG-CWS is currently limited to local administration because of the infectiousness of live BCG and the insolubility of BCG-CWS. We previously developed a water-dispersible nanoparticle (NP) formulation of BCG-CWS (CWS-NP), which could be used to apply BCG components for use as a systemically injected adjuvant for the treatment of cancers other than bladder cancer. In the present study, we examined the possible use of CWS-NP for cancer immunotherapy, when intravenously administered. The CWS-NP was a highly uniform dispersion and showed no aggregation in serum. The intravenously injected CWS-NP accumulated in the spleen and was efficiently taken up by dendritic cells, leading to their maturation. The coadministration of CWS-NP and ovalbumin (OVA) loaded NP resulted in the generation of OVA-specific cytotoxic T cells and inhibited the growth of E.G7-OVA tumors. These results represent the first findings related to the use of systemically injected CWS-NP as an adjuvant for cancer immunotherapy.

Integration of nano drug-delivery system with cancer immunotherapy

Immune checkpoint therapy represents a new, revolutionary type of cancer therapy, but emerging evidence indicates that only a minority of patients will benefit from it. The issue of how to improve and widen the clinical response is a pivotal issue, and combining other types of therapy with immune checkpoint inhibitors is currently under development. A nanotechnology-based drug-delivery system (nano DDS) could be an important contribution to the development of an effective combination therapy. In this document, we review recent findings in the field of tumor immunology, which provide a strategy for an efficient combination therapy, and discuss nano DDS that are associated with cancer immunotherapy and nano DDS strategies based on the immune status in tumor microenvironments.

Nano-BCG: A Promising Delivery System for Treatment of Human Bladder Cancer

Mycobacterium bovis bacillus Calmette–Guerin (BCG) remains at the forefront of immunotherapy for treating bladder cancer patients. However, the incidence of recurrence and progression to invasive cancer is commonly observed. There are no established effective intravesical therapies available for patients, whose tumors recur following BCG treatment, representing an important unmet clinical need. In addition, there are very limited options for patients who do not respond to or tolerate chemotherapy due to toxicities, resulting in poor overall treatment outcomes. Within this context, nanotechnology is an emergent and promising tool for: (1) controlling drug release for extended time frames, (2) combination therapies due to the ability to encapsulate multiple drugs simultaneously, (3) reducing systemic side effects, (4) increasing bioavailability, (5) and increasing the viability of various routes of administration. Moreover, bladder cancer is often characterized by high mutation rates and over expression of tumor antigens on the tumor cell surface. Therapeutic targeting of these biomolecules may be improved by nanotechnology strategies. In this mini-review, we discuss how nanotechnology can help overcome current obstacles in bladder cancer treatment, and how nanotechnology can facilitate combination chemotherapeutic and BCG immunotherapies for the treatment of non-muscle invasive urothelial bladder cancer.

Development of a Drug Delivery System for Cancer Immunotherapy

Delivery systems are a powerful technology for enhancing the effect of cancer immunotherapy. We have been in the process of developing lipid-based delivery systems for controlling the physical properties and dynamics of immunofunctional molecules such as antigens and adjuvants. The lipid nanoparticulation of these molecules improves their physical properties, resulting in a good water dispensability, greater stability, and small size. The cell wall skeleton of bacille Calmette-Guerin (BCG-CWS) could be used to replace live BCG as a drug for treating bladder cancer, but problems associated with the physical properties of BCG-CWS have prevented its use. To overcome such problems, we developed a novel packaging method that permits BCG-CWS to be encapsulated into lipid nanoparticles, which induce antitumor responses against bladder cancer. Lipid nanoparticulation also improves the intracellular trafficking and biodistribution of immunofunctional molecules. Cyclic di-GMP (c-di-GMP) is an adjuvant that is recognized by the cytosolic sensor. However, c-di-GMP cannot pass through the cell membrane. We encapsulated c-di-GMP into lipid nanoparticles containing a pH-responsive lipid that was developed in our laboratory and achieved efficient cytosolic delivery and the induction of antitumor immunity. Furthermore, we are attempting to control the functions of immune cells by RNA interference. We have recently succeeded in the efficient delivery of small interfering RNA into mouse dendritic cells (DCs), which led to the enhancement of antitumor activity of DCs. In this review, our recent efforts regarding cancer immunotherapy using lipid-based nanoparticles are reviewed.