Development of a transferrin receptor-targeting HVJ-E vector

Cytoplasmic calcium increase via fusion with inactivated Sendai virus induces apoptosis in human multiple myeloma cells by downregulation of c-Myc oncogene

Because the emergence of drug resistance is a major limitation of current treatments for multiple myeloma (MM), it is necessary to continuously develop novel anticancer strategies. Here, using an inactivated Sendai virus (Hemagglutinating Virus of Japan; HVJ) envelope (HVJ-E), we discovered that increase of cytoplasmic Ca2+ by virus-cell fusion significantly induced apoptosis against human MM cells but not peripheral blood mononuclear cells from healthy donors. Interaction of F protein of HVJ-E with MM cells increased intracellular Ca2+ level of MMs by the induction of Ca2+ efflux from endoplasmic reticulum but not influx from extracellular region. The elevation of the Ca2+ cytoplasmic level induced SMAD1/5/8 phosphorylation and translocation into the nucleus, and SMAD1/5/8 and SMAD4 complex suppressed c-Myc transcription. Meanwhile, HVJ-E decreases S62 phosphorylation of c-Myc and promotes c-Myc protein degradation. Thus, HVJ-E-induced cell death of MM resulted from suppression of c-Myc by both destabilization of c-Myc protein and downregulation of c-Myc transcription. This study indicates that HVJ-E will be a promising tool for MM therapy.

Oncolytic Sendai virus-based virotherapy for cancer: recent advances

Many drugs have been developed and optimized for the treatment of cancer; however, it is difficult to completely cure cancer with anticancer drugs alone. Therefore, the development of new therapeutic technologies, in addition to new anticancer drugs, is necessary for more effective oncotherapy. Oncolytic viruses are one potential new anticancer strategy. Various oncolytic viruses have been developed for safe and effective oncotherapy. Recently, Sendai virus-based oncotherapy has been reported by several groups, and attention has been drawn to its unique anticancer mechanisms, which are different from those of the conventional oncolytic viruses that kill cancer cells by cancer cell-selective replication. Here, we introduce Sendai virus-based virotherapy and its anticancer mechanisms.

Development of Rous sarcoma Virus-like Particles Displaying hCC49 scFv for Specific Targeted Drug Delivery to Human Colon Carcinoma Cells

PURPOSE

Virus-like particles (VLPs) have been used as drug carriers for drug delivery systems. In this study, hCC49 single chain fragment variable (scFv)-displaying Rous sarcoma virus-like particles (RSV VLPs) were produced in silkworm larvae to be a specific carrier of an anti-cancer drug.

METHOD

RSV VLPs displaying hCC49 scFv were created by the fusion of the transmembrane and cytoplasmic domains of hemagglutinin from influenza A (H1N1) virus and produced in silkworm larvae. The display of hCC49 scFv on the surface of RSV VLPs was confirmed by enzyme-linked immunosorbent assay using tumor-associated glycoprotein-72 (TAG-72), fluorescent microscopy, and immunoelectron microscopy. Fluorescein isothiocyanate (FITC) or doxorubicin (DOX) was incorporated into hCC49 scFv-displaying RSV VLPs by electroporation and specific targeting of these VLPs was investigated by fluorescent microscopy and cytotoxicity assay using LS174T cells.

RESULTS

FITC was delivered to LS174T human colon adenocarcinoma cells by hCC49 scFv-displaying RSV VLPs, but not by RSV VLPs. This indicated that hCC49 scFv allowed FITC-loaded RSV VLPs to be delivered to LS174T cells. DOX, which is an anti-cancer drug with intrinsic red fluorescence, was also loaded into hCC49 scFv-displaying RSV VLPs by electroporation; the DOX-loaded hCC49 scFv-displaying RSV VLPs killed LS174T cells via the specific delivery of DOX that was mediated by hCC49 scFv. HEK293 cells were alive even though in the presence of DOX-loaded hCC49 scFv-displaying RSV VLPs.

CONCLUSION

These results showed that hCC49 scFv-displaying RSV VLPs from silkworm larvae offered specific drug delivery to colon carcinoma cells in vitro. This scFv-displaying enveloped VLP system could be applied to drug and gene delivery to other target cells.

Self-focusing therapeutic gene delivery with intelligent gene vector swarms: intra-swarm signalling through receptor transgene expression in targeted cells

BACKGROUND

Gene delivery in vivo that is tightly focused on the intended target cells is essential to maximize the benefits of gene therapy and to reduce unwanted side-effects. Cell surface markers are immediately available for probing by therapeutic gene vectors and are often used to direct gene transfer with these vectors to specific target cell populations. However, it is not unusual for the choice of available extra-cellular markers to be too scarce to provide a reliable definition of the desired therapeutically relevant set of target cells. Therefore, interrogation of intra-cellular determinants of cell-specificity, such as tissue-specific transcription factors, can be vital in order to provide detailed cell-guiding information to gene vector particles. An important improvement in cell-specific gene delivery can be achieved through auto-buildup in vector homing efficiency using intelligent 'self-focusing' of swarms of vector particles on target cells. Vector self-focusing was previously suggested to rely on the release of diffusible chemo-attractants after a successful target-specific hit by 'scout' vector particles.

HYPOTHESIS

I hypothesize that intelligent self-focusing behaviour of swarms of cell-targeted therapeutic gene vectors can be accomplished without the employment of difficult-to-use diffusible chemo-attractants, instead relying on the intra-swarm signalling through cells expressing a non-diffusible extra-cellular receptor for the gene vectors. In the proposed model, cell-guiding information is gathered by the 'scout' gene vector particles, which: (1) attach to a variety of cells via a weakly binding (low affinity) receptor; (2) successfully facilitate gene transfer into these cells; (3) query intra-cellular determinants of cell-specificity with their transgene expression control elements and (4) direct the cell-specific biosynthesis of a vector-encoded strongly binding (high affinity) cell-surface receptor. Free members of the vector swarm loaded with therapeutic cargo are then attracted to and internalized into the intended target cells via the expressed cognate strongly binding extra-cellular receptor, causing escalation of gene transfer into these cells and increasing the copy number of the therapeutic gene expression modules. Such self-focusing swarms of gene vectors can be either homogeneous, with 'scout' and 'therapeutic' members of the swarm being structurally identical, or, alternatively, heterogeneous (split), with 'scout' and 'therapeutic' members of the swarm being structurally specialized.

CONCLUSIONS

It is hoped that the proposed self-focusing cell-targeted gene vector swarms with receptor-mediated intra-swarm signalling could be particularly effective in 'top-up' gene delivery scenarios, achieving high-level and sustained expression of therapeutic transgenes that are prone to shut-down through degradation and silencing. Crucially, in contrast to low-precision 'general location' vector guidance by diffusible chemo-attractants, ear-marking non-diffusible receptors can provide high-accuracy targeting of therapeutic vector particles to the specific cell, which has undergone a 'successful cell-specific hit' by a 'scout' vector particle. Opportunities for cell targeting could be expanded, since in the proposed model of self-focusing it could be possible to probe a broad selection of intra-cellular determinants of cell-specificity and not just to rely exclusively on extra-cellular markers of cell-specificity. By employing such self-focusing gene vectors for the improvement of cell-targeted delivery of therapeutic genes, e.g., in cancer therapy or gene addition therapy of recessive genetic diseases, it could be possible to broaden a leeway for the reduction of the vector load and, consequently, to minimize undesired vector cytotoxicity, immune reactions, and the risk of inadvertent genetic modification of germline cells in genetic treatment in vivo.

Virosome presents multimodel cancer therapy without viral replication

A virosome is an artificial envelope that includes viral surface proteins and lacks the ability to produce progeny virus. Virosomes are able to introduce an encapsulated macromolecule into the cytoplasm of cells using their viral envelope fusion ability. Moreover, virus-derived factors have an adjuvant effect for immune stimulation. Therefore, many virosomes have been utilized as drug delivery vectors and adjuvants for cancer therapy. This paper introduces the application of virosomes for cancer treatment. In Particular, we focus on virosomes derived from the influenza and Sendai viruses which have been widely used for cancer therapy. Influenza virosomes have been mainly applied as drug delivery vectors and adjuvants. By contrast, the Sendai virosomes have been mainly applied as anticancer immune activators and apoptosis inducers.

A novel photodynamic therapy for drug-resistant prostate cancer cells using porphyrus envelope as a novel photosensitizer

BACKGROUND

In the clinic, it is often very difficult to treat drug-resistant advanced prostate cancer by conventional treatments. Photodynamic therapy (PDT) is a minimally invasive treatment that takes advantage of photochemical reactions between a photosensitizer and light. On the basis of several of its key characteristics, PDT is considered to be a promising novel method for treating drug-resistant prostate cancer.

OBJECTIVES

For effective treatment of drug-resistant prostate cancer, we developed a novel agent termed porphyrus envelope, which was produced from PpIX lipid and hemagglutinating virus of Japan envelope (HVJ-E).

MATERIALS AND METHODS

We inserted PpIX lipid into HVJ-E by centrifugation, and used the resultant porphyrus envelope in PDT of two drug-resistant prostate cancer cell lines, PC-3 and PC-3-DR.

RESULTS

Porphyrus envelope enhanced uptake of PpIX, and cytotoxicity of PDT, relative to free PpIX lipid or PpIX induced by 5-ALA.

CONCLUSION

PDT using porphyrus envelope has potential as a method for treating drug-resistant prostate cancer.

Systemic administration of a novel immune-stimulatory pseudovirion suppresses lung metastatic melanoma by regionally enhancing IFN-γ production

PURPOSE

Cancer immunotherapy has encountered many difficulties in the face of the expectation to eradicate cancer, and new breakthroughs are required. We have previously shown that UV-inactivated Sendai virus particles (hemagglutinating virus of Japan envelope; HVJ-E) induce immunity against multiple tumor types. In this study, a novel pseudovirion that stimulates more robust antitumor immunity was designed for cancer treatment.

EXPERIMENTAL DESIGN

First, we found that culturing murine splenocytes with HVJ-E in combination with interleukin (IL)-12 resulted in a remarkable increase in IFN-γ production compared with that observed in splenocytes cultured with IL-12 alone. The synergistic effects of HVJ-E and IL-12 on IFN-γ production were caused by viral F proteins independently of HVJ-E fusion activity and not by hemagglutination from hemagglutinin-neuraminidase (HN) proteins. We next constructed HN-depleted HVJ-E expressing the Fc region of immunoglobulin G (IgG) on the envelope and single-chain IL-12 containing the ZZ domain of protein A to produce an IL-12-conjugated HVJ-E particle without hemagglutinating activity.

RESULTS

IL-12-conjugated HVJ-E dramatically enhanced the amount of IFN-γ produced by immune cells. Intratumoral injection of IL-12-conjugated HVJ-E eradicated murine melanomas more effectively than injection of wild-type HVJ-E through increased production of melanoma-specific CTLs. IL-12-conjugated HVJ-E preferentially accumulated in the lungs after systemic administration. When small metastatic melanoma foci were formed in the lungs, systemic administration of IL-12-conjugated HVJ-E significantly reduced the number of metastatic foci by inducing local production of IFN-γ in the lungs and generating large numbers of melanoma-specific CTLs.

CONCLUSION

IL-12-conjugated HVJ-E is a promising tool for the treatment of cancers, including lung metastasis.

In vitro investigation of efficient photodynamic therapy using a nonviral vector; hemagglutinating virus of Japan envelope

Photodynamic therapy (PDT) is a photochemical modality approved for cancer treatment. PDT has demonstrated efficacy in early stage lung cancer and esophageal cancer. The accumulation of photosensitizers in cancer cells is necessary to enhance the therapeutic benefits of PDT; however, photosensitizers have low uptake efficiency. To overcome this limitation, a drug delivery system, such as the hemagglutinating virus of Japan envelope (HVJ-E) vector, is required. In this study, the combination of PDT and HVJ-E was investigated for enhancing the efficacy of PDT. The photosensitizers that were evaluated included 5-aminolaevulinic acid (5-ALA), protoporphyrin IX (PPIX), and HVJ-PPIX. The uptake of the photosensitizers as increased twenty-fold with the addition of HVJ-E. The cytotoxicity of conventional 5-ALA was enhanced by the addition of HVJ-E vector. In conclusion, HVJ-E vector improved the uptake of photosensitizers and the PDT effect.

In vitro investigation of efficient photodynamic therapy using a nonviral vector; hemagglutinating virus of Japan envelope

Photodynamic therapy (PDT) is a photochemical modality approved for cancer treatment. PDT has demonstrated efficacy in early stage lung cancer and esophageal cancer. The accumulation of photosensitizers in cancer cells is necessary to enhance the therapeutic benefits of PDT; however, photosensitizers have low uptake efficiency. To overcome this limitation, a drug delivery system, such as the hemagglutinating virus of Japan envelope (HVJ-E) vector, is required. In this study, the combination of PDT and HVJ-E was investigated for enhancing the efficacy of PDT. The photosensitizers that were evaluated included 5-aminolaevulinic acid (5-ALA), protoporphyrin IX (PPIX), and HVJ-PPIX. The uptake of the photosensitizers as increased twenty-fold with the addition of HVJ-E. The cytotoxicity of conventional 5-ALA was enhanced by the addition of HVJ-E vector. In conclusion, HVJ-E vector improved the uptake of photosensitizers and the PDT effect.

Virosome: a novel vector to enable multi-modal strategies for cancer therapy

Despite advancements in treatments, cancer remains a life-threatening disease that is resistant to therapy. Single-modal cancer therapy is often insufficient to provide complete remission. A revolution in cancer therapy may someday be provided by vector-based gene and drug delivery systems. However, it remains difficult to achieve this aim because viral and non-viral vectors have their own advantages and limitations. To overcome these limitations, virosomes have been constructed by combining viral components with non-viral vectors or by using pseudovirions without viral genome replication. Viruses, such as influenza virus, HVJ (hemagglutinating virus of Japan; Sendai virus) and hepatitis B virus, have been used in the construction of virosomes. The HVJ-derived vector is particularly promising due to its highly efficient delivery of DNA, siRNA, proteins and anti-cancer drugs. Furthermore, the HVJ envelope (HVJ-E) vector has intrinsic anti-tumor activities including the activation of multiple anti-tumor immunities and the induction of cancer-selective apoptosis. HVJ-E is currently being clinically used for the treatment of melanoma. A promising multi-modal cancer therapy will be achieved when virosomes with intrinsic anti-tumor activities are utilized as vectors for the delivery of anti-tumor drugs and genes.

The transferrin receptor and the targeted delivery of therapeutic agents against cancer

BACKGROUND

Traditional cancer therapy can be successful in destroying tumors, but can also cause dangerous side effects. Therefore, many targeted therapies are in development. The transferrin receptor (TfR) functions in cellular iron uptake through its interaction with transferrin. This receptor is an attractive molecule for the targeted therapy of cancer since it is upregulated on the surface of many cancer types and is efficiently internalized. This receptor can be targeted in two ways: 1) for the delivery of therapeutic molecules into malignant cells or 2) to block the natural function of the receptor leading directly to cancer cell death.

SCOPE OF REVIEW

In the present article we discuss the strategies used to target the TfR for the delivery of therapeutic agents into cancer cells. We provide a summary of the vast types of anti-cancer drugs that have been delivered into cancer cells employing a variety of receptor binding molecules including Tf, anti-TfR antibodies, or TfR-binding peptides alone or in combination with carrier molecules including nanoparticles and viruses.

MAJOR CONCLUSIONS

Targeting the TfR has been shown to be effective in delivering many different therapeutic agents and causing cytotoxic effects in cancer cells in vitro and in vivo.

GENERAL SIGNIFICANCE

The extensive use of TfR for targeted therapy attests to the versatility of targeting this receptor for therapeutic purposes against malignant cells. More advances in this area are expected to further improve the therapeutic potential of targeting the TfR for cancer therapy leading to an increase in the number of clinical trials of molecules targeting this receptor. This article is part of a Special Issue entitled Transferrins: molecular mechanisms of iron transport and disorders.

A non-replicating oncolytic vector as a novel therapeutic tool against cancer

Cancers are still difficult targets despite recent advances in cancer therapy. Due to the heterogeneity of cancer, a single-treatment modality is insufficient for the complete elimination of cancer cells. Therapeutic strategies from various aspects are needed. Gene therapy has been expected to bring a breakthrough to cancer therapy, but it has not yet been successful. Gene therapy also should be combined with other treatments to enhance multiple therapeutic pathways. In this view, gene delivery vector itself should be equipped with intrinsic anti-cancer activities. HVJ (hemagglutinating virus of Japan; Sendai virus) envelope vector (HVJ-E) was developed to deliver therapeutic molecules. HVJ-E itself possessed anti-tumor activities such as the generation of anti-tumor immunities and the induction of cancer-selective apoptosis. In addition to the intrinsic anti-tumor activities, therapeutic molecules incorporated into HVJ-E enabled to achieve multi-modal therapeutic strategies in cancer treatment. Tumor-targeting HVJ-E was also developed. Thus, HVJ-E will be a novel promising tool for cancer treatment.

Sterile alpha motif containing domain 9 is involved in death signaling of malignant glioma treated with inactivated Sendai virus particle (HVJ-E) or type I interferon

Malignant glioma is one of the most aggressive cancers. For the development of effective therapeutic strategies against such malignant diseases, elucidation of molecular targets is necessary. We found that inactivated Sendai virus particle (HVJ-E) induced extensive cell death in the human glioblastoma cell line U251MG. Intradermal U251MG tumors were more effectively suppressed by HVJ-E than interferon (IFN)-beta. From microarray analysis of gene expression in U251MG cells treated with HVJ-E, we focused on the up-regulation of sterile alpha motif containing domain 9 (SAMD9) gene. The expression of the SAMD9 gene was induced by administration of recombinant human IFN-alpha, -beta or -gamma. The up-regulation of the SAMD9 gene by HVJ-E treatment was abrogated by IFN receptor blocking antibody or JAK inhibitor treatment. When SAMD9 expression was knocked down by RNA interference, apoptotic cell death induced by HVJ-E was blocked in U251MG cells. Suppression of SAMD9 using SAMD9 siRNA also inhibited IFN-beta-induced death in U251MG cells with a small, but significant, difference to control groups. However, overexpression of the SAMD9 gene failed to induce significant cell death in U251MG cells. Thus, SAMD9 could be a key molecule to control cancer cell death by HVJ-E or IFN-beta treatment.

Ligand-based dual target drug design for H1N1: swine flu--a preliminary first study

In March and April, 2009, an outbreak of H1N1 influenza in Mexico had led to hundreds of confirmed cases and the death toll had risen to 160. The worldwide spread of H1N1 has been attracting global attention and arising an overwhelming fear. So far, the vaccine and remedy has been in urgent need. In this study, a QSAR model and pharmacophore map of neuraminidase (NA) type 1 (N1) contained two hydrogen bond acceptor features, one hydrogen bond donor feature, and one positive ionizable feature. NCI database was employed in virtual screen by the N1 pharmacophore map features. After screening, compounds were obtained and then docked into haemagglutinin type 1 (H1) to find out the candidate drugs for dual target of both N1 and H1. The candidate, NCI0353858, selected via virtual screening and docking, might be functional to this worldwide disease; consequently, further clinical investigations and scientific application are urgently demanded. We realize the proposed ligand does not have much validity without conducting a study on the stability of the protein-ligand complex by MD simulations and binding free energy, and such a study is underway and will be reported later in this journal. Nevertheless, the present study is clear, consistent and could give a rational explanation for the binding mode of the best selected ligand.

Efficient eradication of hormone-resistant human prostate cancers by inactivated Sendai virus particle

Hormone-refractory prostate cancer is one of the intractable human cancers in the world. Here, we examined the direct tumor-killing activity of inactivated Sendai virus particle [hemagglutinating virus of Japan envelope (HVJ-E)] through induction of Type I interferon (IFN) in the hormone-resistant human prostate cancer cell lines PC3 and DU145. Preferential binding of HVJ-E to PC3 and DU145 over hormone-sensitive prostate cancer cell and normal prostate epithelium was observed, resulting in a number of fused cells. After HVJ-E treatment, a number of IFN-related genes were up-regulated, resulting in Type I IFN production in PC3 cells. Then, retinoic acid-inducible gene-I (RIG-I) helicase which activates Type I IFN expression after Sendai virus infection was up-regulated in cancer cells after HVJ-E treatment. Produced IFN-alpha and -beta enhanced caspase 8 expression via Janus kinases/Signal Transducers and Activators of Transcription pathway, activated caspase 3 and induced apoptosis in cancer cells. When HVJ-E was directly injected into a mass of PC3 tumor cells in SCID (severe combined immunodeficiency) mice, a marked reduction in the bulk of each tumor mass was observed and 85% of the mice became tumor-free. Although co-injection of an anti-asialo GM1 antibody with HVJ-E into each tumor mass slightly attenuated the tumor suppressive activity of HVJ-E, significant suppression of tumor growth was observed even in the presence of anti-asialo GM1 antibody. This suggests that natural killer cell activation made small contribution to tumor regression following HVJ-E treatment in hormone-resistant prostate cancer model in vivo. Thus, HVJ-E effectively targets hormone-resistant prostate cancer by inducing apoptosis in tumor cells, as well as activating anti-tumor immunity.