Current status of gene therapy for cancer

An Overview: Genetic Tumor Markers for Early Detection and Current Gene Therapy Strategies

Genomic instability is considered a fundamental factor involved in any neoplastic disease. Consequently, the genetically unstable cells contribute to intratumoral genetic heterogeneity and phenotypic diversity of cancer. These genetic alterations can be detected by several diagnostic techniques of molecular biology and the detection of alteration in genomic integrity may serve as reliable genetic molecular markers for the early detection of cancer or cancer-related abnormal changes in the body cells. These genetic molecular markers can detect cancer earlier than any other method of cancer diagnosis, once a tumor is diagnosed, then replacement or therapeutic manipulation of these cancer-related abnormal genetic changes can be possible, which leads toward effective and target-specific cancer treatment and in many cases, personalized treatment of cancer could be performed without the adverse effects of chemotherapy and radiotherapy. In this review, we describe how these genetic molecular markers can be detected and the possible ways for the application of this gene diagnosis for gene therapy that can attack cancerous cells, directly or indirectly, which lead to overall improved management and quality of life for a cancer patient.

Advances and Prospects of Prolamine Corn Protein Zein as Promising Multifunctional Drug Delivery System for Cancer Treatment

Zein is a type of prolamine protein that is derived from corn, and it has been recognized by the US FDA as one of the safest biological materials available. Zein possesses valuable characteristics that have made it a popular choice for the preparation of drug carriers, which can be administered through various routes to improve the therapeutic effect of antitumor drugs. Additionally, zein contains free hydroxyl and amino groups that offer numerous modification sites, enabling it to be hybridized with other materials to create functionalized drug delivery systems. However, despite its potential, the clinical translation of drug-loaded zein-based carriers remains challenging due to insufficient basic research and relatively strong hydrophobicity. In this paper, we aim to systematically introduce the main interactions between loaded drugs and zein, administration routes, and the functionalization of zein-based antitumor drug delivery systems, in order to demonstrate its development potential and promote their further application. We also provide perspectives and future directions for this promising area of research.

Silencing of SiX-4 enhances the chemosensitivity of melanoma cells to Cisplatin

Melanoma is the riskiest type of skin cancer. Its prevalence has been rapidly increased over the last three decades. SIX1, SIX2, SIX3, SIX4, SIX5, and SIX6 are members of the sine oculis homeobox (SIX) homolog family. It is imperative to identify new melanoma biomarkers to improve the predictive value for melanoma prognosis, which could enhance our understanding of carcinogenesis and tumor progression. In this study, we investigated whether silencing of SIX4 in a melanoma cell line (A375 cells) in combination with Cisplatin can affect the apoptosis and suppression of cell cycle progression, migration of the melanoma cells. MTT test and colony formation assay was applied to determine the IC50 of Cisplatin and the combined effect of SIX4 siRNA and Cisplatin on the viability and clonogenesis of the A-375 cells. qRT-PCR was performed to determine the c-myc, BCL-2, BAX, MMP-9, CXCR4, and Rock genes expression. Furthermore, flow cytometry was applied to evaluate apoptosis, autophagy, and the cell cycle status in different groups. Finally, wound healing assay was employed to evaluate the effect of this combination therapy on migratory capacity. SIX4 suppression increased the chemosensitivity of A-375 cells to Cisplatin and decreased its efficient dose. Furthermore, SIX4 suppression alongside Cisplatin reduced cell migration rate, arrested the cell cycle at the G1 phase, induced apoptosis by modulating the expression of apoptotic target genes, induced autophagy, and also significantly inhibits clonogenesis of A-375 cells. SIX4 plays a significant role in the chemosensitivity and pathogenesis of melanoma. Therefore, SIX4 suppression, in combination with Cisplatin, may be a promising therapeutic approach in treating melanoma.

Claudin-Targeted Suicide Gene Therapy for Claudin-Overexpressing Tumor Cells by Using Modified Clostridium perfringens Enterotoxin (CPE)

Bacterial toxins gain growing attention as potential cancer treatment due to their potent cytotoxic effects. Among the very different toxins with diverse modes of action, the Clostridium perfringens enterotoxin (CPE) is in focus to treat solid cancers. This toxin targets the tight junction proteins claudin-3 and -4 (Cldn-3/4), which are frequently overexpressed in solid cancers. Binding to these claudins induces pore formation in the host cell plasma membrane leading to rapid oncoleaking cell death of tumor cells. Based on this, extending the targeting of CPE beyond Cldn-3/4 is of interest, since other claudins, such as claudin-1 or -5 are often overexpressed in various cancer entities such as non-small-cell lung cancer (NSCLC) or papillary thyroid carcinoma. In this chapter we describe the modification of a CPE-encoding vector by structure-directed mutagenesis to either preferentially target Cldn-1 and -5 or to expand targeting to Cldn1-9 for improved broadened cytotoxic targeting of claudin-overexpressing tumors such as but not limited to lung cancer via CPE gene transfer.

Treating Bladder Cancer: Engineering of Current and Next Generation Antibody-, Fusion Protein-, mRNA-, Cell- and Viral-Based Therapeutics

Bladder cancer is a frequent malignancy and has a clinical need for new therapeutic approaches. Antibody and protein technologies came a long way in recent years and new engineering approaches were applied to generate innovative therapeutic entities with novel mechanisms of action. Furthermore, mRNA-based pharmaceuticals recently reached the market and CAR-T cells and viral-based gene therapy remain a major focus of biomedical research. This review focuses on the engineering of biologics, particularly therapeutic antibodies and their application in preclinical development and clinical trials, as well as approved monoclonal antibodies for the treatment of bladder cancer. Besides, newly emerging entities in the realm of bladder cancer like mRNA, gene therapy or cell-based therapeutics are discussed and evaluated. As many discussed molecules exhibit unique mechanisms of action based on innovative protein engineering, they reflect the next generation of cancer drugs. This review will shed light on the engineering strategies applied to develop these next generation treatments and provides deeper insights into their preclinical profiles, clinical stages, and ongoing trials. Furthermore, the distribution and expression of the targeted antigens and the intended mechanisms of action are elucidated.

Electrospun Nanofibers for Cancer Therapy

Lately, a remarkable progress has been recorded in the field of electrospinning for the preparation of numerous types of nanofiber scaffolds. These scaffolds present some remarkable features including high loading capacity and encapsulation efficiency, superficial area and porosity, potential for modification, structure for the co-delivery of various therapies, and cost-effectiveness. Their present and future applications for cancer diagnosis and treatment are promising and pioneering. In this chapter we provide a comprehensive overview of electrospun nanofibers (ESNFs) applications in cancer diagnosis and treatment, covering diverse types of drug-loaded electrospun nanofibers.

Efficient nanocarriers of siRNA therapeutics for cancer treatment

Nanocarriers as drug delivery systems are promising and becoming popular, especially for cancer treatment. In addition to improving the pharmacokinetics of poorly soluble hydrophobic drugs by solubilizing them in a hydrophobic core, nanocarriers allow cancer-specific combination drug deliveries by inherent passive targeting phenomena and adoption of active targeting strategies. Nanoparticle-drug formulations can enhance the safety, pharmacokinetic profiles, and bioavailability of locally or systemically administered drugs, leading to improved therapeutic efficacy. Gene silencing by RNA interference (RNAi) is rapidly developing as a personalized field of cancer treatment. Small interfering RNAs (siRNAs) can be used to switch off specific cancer genes, in effect, "silence the gene, silence the cancer." siRNA can be used to silence specific genes that produce harmful or abnormal proteins. The activity of siRNA can be used to harness cellular machinery to destroy a corresponding sequence of mRNA that encodes a disease-causing protein. At present, the main barrier to implementing siRNA therapies in clinical practice is the lack of an effective delivery system that protects the siRNA from nuclease degradation, delivers to it to cancer cells, and releases it into the cytoplasm of targeted cancer cells, without creating adverse effects. This review provides an overview of various nanocarrier formulations in both research and clinical applications with a focus on combinations of siRNA and chemotherapeutic drug delivery systems for the treatment of multidrug resistant cancer. The use of various nanoparticles for siRNA-drug delivery, including liposomes, polymeric nanoparticles, dendrimers, inorganic nanoparticles, exosomes, and red blood cells for targeted drug delivery in cancer is discussed.

Cancer Suicide Gene Therapy with TK.007

Cancer is a devastating disease characterized by uncontrolled and aggressive cell growth. Suicide gene therapy (SGT) facilitating induction of malignancy-specific cell death represents a novel therapeutic approach to treat cancer, which has been investigated in several cancer types with very promising results. In addition, SGT has been suggested as a safeguard in adoptive immunotherapy and regenerative-medicine settings. Generally, SGT consists of two steps-vector-mediated delivery of suicide genes into tumors and subsequent activation of the suicide mechanism, e.g., by administration of a specific prodrug. This chapter provides a framework of protocols for basic and translational research using the Herpes-simplex-virus thymidine kinase (HSV-TK)/ganciclovir (GCV) system, the most widely used suicide gene approach. The protocols provide standard guidelines for the preparation of high-titer third-generation lentiviral vectors encoding a genetically improved HSV-TK version known as TK.007 and its application in in vitro and in vivo treatment setups.

The development of interferon-based gene therapy for BCG unresponsive bladder cancer: from bench to bedside

BACKGROUND AND PURPOSE

BCG unresponsive bladder cancer is an inherently resistant disease state for which the preferred treatment is radical cystectomy. To date, no effective intravesical therapies exist for patients who possess these resistant tumors. For this reason, many research groups are actively investigating/testing novel therapeutic agents to aid in bladder preservation for this patient population. This review article describes our 15-year experience developing and testing IFN-based gene therapy.

METHODS

A comprehensive review was performed of all studies pertaining to IFN-based gene therapy for non-muscle invasive bladder cancer from 2003 to 2018.

RESULTS AND CONCLUSIONS

Over the past two decades, gene therapy has evolved into a powerful tool in our fight against cancer. After overcoming the initial barriers associated with gene delivery to the bladder, we have made significant strides forward in developing this novel therapeutic strategy for the treatment of this inherently resistant disease state. Our results to date are very encouraging; however, much work lies ahead to better understand and optimize this novel approach for treating non-muscle invasive bladder.

Intradermal delivery of STAT3 siRNA to treat melanoma via dissolving microneedles

Hyperactivity of signal transducer and activity of transcription 3 (STAT3) plays a crucial role in melanoma invasion and metastasis. Gene therapy applying siRNA targeting STAT3 is a potential therapeutic strategy for melanoma. In this article, we first fabricated safe and novel dissolving microneedles (MNs) for topical application of STAT3 siRNA to enhance the skin penetration of siRNA and used polyethylenimine (PEI, 25 kDa) as carrier to improve cellular uptake of siRNA. The results showed that MNs can effectively penetrate skin and rapidly dissolve in the skin. In vitro B16F10 cell experiments presented that STAT3 siRNA PEI complex can enhance cellular uptake and transfection of siRNA, correspondingly enhance gene silencing efficiency and inhibit tumor cells growth. In vivo experiments indicated that topical application of STAT3 siRNA PEI complex delivered by dissolving MNs into skin can effectively suppress the development of melanoma through silencing STAT3 gene, and the inhibition effect is dose-dependent. STAT3 siRNA delivery via dissolving MNs is a promising approach for skin melanoma treatment with targeting inhibition efficacy and minimal adverse effects.

A gene-activating skin substitute comprising PLLA/POSS nanofibers and plasmid DNA encoding ANG and bFGF promotes in vivo revascularization and epidermalization

A gene-activated porous nanofibrous scaffold for effectively promoting vascularization, epidermalization and dermal wound healing by sustained release of dual plasmid DNAs.

Extracellular vesicles as regulators of tumor fate: crosstalk among cancer stem cells, tumor cells and mesenchymal stem cells

The tumor microenvironment comprises a heterogeneous population of tumorigenic and non-tumorigenic cells. Cancer stem cells (CSCs) and mesenchymal stem cells (MSCs) are components of this microenvironment and have been described as key regulators of different aspects of tumor physiology. They act differently on the tumor: CSCs are described as tumor initiators and are associated with tumor growth, drug resistance and metastasis; MSCs can integrate the tumor microenvironment after recruitment and interact with cancer cells to promote tumor modifications. Extracellular vesicles (EVs) have emerged as an important mechanism of cell communication under the physiological and pathological conditions. In cancer, secretion of EVs seems to be one of the main mechanisms by which stem cells interact with other tumor and non-tumor cells. The transfer of bioactive molecules (lipids, proteins and RNAs) compartmentalized into EVs triggers different responses in the target cells, regulating several processes in the tumor as angiogenesis, tumor invasiveness and immune escape. This review focuses on the role of CSCs and MSCs in modulating the tumor microenvironment through secretion of EVs, addressing different aspects of the multidirectional interactions among stem cells, tumor and tumor-associated cells.

Natural and artificial small RNAs: a promising avenue of nucleic acid therapeutics for cancer

Since the failure of traditional therapy, gene therapy using functional DNA sequence and small RNA/DNA molecules (oligonucleotide) has become a promising avenue for cancer treatment. The discovery of RNA molecules has impelled researchers to investigate small regulatory RNA from various natural and artificial sources and determine a cogent target for controlling tumor progression. Small regulatory RNAs are used for therapeutic silencing of oncogenes and aberrant DNA repair response genes. Despite their advantages, therapies based on small RNAs exhibit limitations in terms of stability of therapeutic drugs, precision-based delivery in tissues, precision-based intercellular and intracellular targeting, and tumor heterogeneity-based responses. In this study, we summarize the potential and drawbacks of small RNAs in nucleic acid therapeutics for cancer.

Antibody-targeted nanoparticles for cancer treatment

Nanoparticles (NPs) are diverse and versatile with physical properties that can be employed for use in cancer medicine. Targeting NPs using antibodies and antibody fragments could overcome some of the limitations seen with current targeted therapies. This review will discuss the role of antibody-targeted NPs in the treatment of cancer: as delivery vehicles, targeted theranostic agents and in the evolving field of cancer hyperthermia.

Phosphorothioate‑modified antisense oligonucleotides against human telomerase reverse transcriptase sensitize cancer cells to radiotherapy

Emergence of resistance, unavoidable systemic toxicity and unsatisfactory efficacy arethe main obstacles for traditional cancer therapy. Combination with phosphorothioate modified antisense oligonucleotides (PS‑ASODN) against human telomerase reverse transcriptase (hTERT) may enhance the therapeutic effect of irradiation. However, the effect of PS‑ASODN against hTERT on the anti‑tumor effects of irradiation in liver cancer remain unclear. In the current study, Walker 256 cells were transfected with hTERT PS‑ASODN. Cell proliferation and cell viability were measured using the MTT assay and cell senescence was examined by SA‑β‑gal staining. Telomerase activity was determined by telomeric repeat amplification protocol‑polymerase chain reaction‑ELISA. Cell apoptosis was assayed by flow cytometry and DNA damage was determined by the comet assay.The PS‑ASODN was demonstrated to have an inhibitory effect on cell proliferation and accelerated effect on cell senescence by inhibiting telomerase activity. PS‑ASODN promoted the irradiation‑induced inhibition of cell viability and telomerase activity, and irradiation‑induced DNA damage and cell apoptosis via the activation of apoptosis‑associated proteins. Taken together, these results indicated that combined treatment of PS‑ASODN with irradiation significantly enhanced tumor inhibition. Therefore, PS‑ASODN provides an experimental foundation for gene therapy and is proposed for application in clinical treatment of liver cancer combined with radiotherapy.

A nonviral vector with transfection activity comparable with adenoviral transduction

AIM

Viral vectors are used commonly in gene therapy trials, but their potential toxic effects are a serious concern. Identification of highly efficient nonviral vectors may alleviate these effects. Results & methodology: We compared the abilities of TransfeX, TransIT-LT1 and adenovirus to deliver the firefly luciferase and green fluorescent protein genes into HeLa cervical carcinoma, and HSC-3 and H357 oral squamous cell carcinoma cells. TransfeX mediated fourfold higher gene expression in HeLa cells than adenovirus, even at the highest multiplicity of infection. Flow cytometry indicated that a population of transfected cells expresses higher levels of green fluorescent protein than transduced cells.

CONCLUSION

TransfeX may be useful for gene therapy applications, particularly where the use of adenovirus is contraindicated.

Delivery strategies and potential targets for siRNA in major cancer types

Small interfering RNA (siRNA) has gained attention as a potential therapeutic reagent due to its ability to inhibit specific genes in many genetic diseases. For many years, studies of siRNA have progressively advanced toward novel treatment strategies against cancer. Cancer is caused by various mutations in hundreds of genes including both proto-oncogenes and tumor suppressor genes. In order to develop siRNAs as therapeutic agents for cancer treatment, delivery strategies for siRNA must be carefully designed and potential gene targets carefully selected for optimal anti-cancer effects. In this review, various modifications and delivery strategies for siRNA delivery are discussed. In addition, we present current thinking on target gene selection in major tumor types.

Design of virus-based nanomaterials for medicine, biotechnology, and energy

This review provides an overview of recent developments in "chemical virology." Viruses, as materials, provide unique nanoscale scaffolds that have relevance in chemical biology and nanotechnology, with diverse areas of applications. Some fundamental advantages of viruses, compared to synthetically programmed materials, include the highly precise spatial arrangement of their subunits into a diverse array of shapes and sizes and many available avenues for easy and reproducible modification. Here, we will first survey the broad distribution of viruses and various methods for producing virus-based nanoparticles, as well as engineering principles used to impart new functionalities. We will then examine the broad range of applications and implications of virus-based materials, focusing on the medical, biotechnology, and energy sectors. We anticipate that this field will continue to evolve and grow, with exciting new possibilities stemming from advancements in the rational design of virus-based nanomaterials.

Topical and Targeted Delivery of siRNAs to Melanoma Cells Using a Fusion Peptide Carrier

Topical application of siRNAs through the skin is a potentially effective strategy for the treatment of melanoma tumors. In this study, we designed a new and safe fusion peptide carrier SPACE-EGF to improve the skin and cell penetration function of the siRNAs and their targeting ability to B16 cells, such that the apoptosis of B16 cells can be induced. The results show that the carrier is stable and less toxic. The EGF motif does not affect the skin and cell penetration function of the SPACE. Because EGF can strongly bind EGFR, which is overexpressed in cancer cells, the targeting ability of the SPACE-EGF-siRNA complex is increased. In vitro experiments indicate that GAPDH siRNAs conjugated with SPACE-EGF can significantly reduce the GAPDH concentration in B16 cells, and c-Myc siRNAs can cause the gene silencing of c-Myc and thus the apoptosis of cells. In vivo experiments show that the topical application of c-Myc siRNAs delivered by SPACE-EGF through the skin can significantly inhibit the growth of melanoma tumors. This work may provide insight into the development of new transdermal drug carriers to treat a variety of skin disorders.

Efficient inhibition of ovarian cancer by degradable nanoparticle-delivered survivin T34A gene

Gene therapy has promising applications in ovarian cancer therapy. Blocking the function of the survivin protein could lead to the growth inhibition of cancer cells. Herein, we used degradable heparin–polyethyleneimine (HPEI) nanoparticles to deliver a dominant-negative human survivin T34A (hs-T34A) gene to treat ovarian cancer. HPEI nanoparticles were characterized and were found to have a dynamic diameter of 66±4.5 nm and a zeta potential of 27.1±1.87 mV. The constructed hs-T34A gene expression plasmid could be effectively delivered into SKOV3 ovarian carcinoma cells by HPEI nanoparticles with low cytotoxicity. Intraperitoneal administration of HPEI/hs-T34A complexes could markedly inhibit tumor growth in a mouse xenograft model of SKOV3 human ovarian cancer. Moreover, according to our results, apparent apoptosis of cancer cells was observed both in vitro and in vivo. Taken together, the prepared HPEI/hs-T34A formulation showed potential applications in ovarian cancer gene therapy.

Trial Watch-Oncolytic viruses and cancer therapy

Oncolytic virotherapy relies on the administration of non-pathogenic viral strains that selectively infect and kill malignant cells while favoring the elicitation of a therapeutically relevant tumor-targeting immune response. During the past few years, great efforts have been dedicated to the development of oncolytic viruses with improved specificity and potency. Such an intense wave of investigation has culminated this year in the regulatory approval by the US Food and Drug Administration (FDA) of a genetically engineered oncolytic viral strain for use in melanoma patients. Here, we summarize recent preclinical and clinical advances in oncolytic virotherapy.

Multifunctional cationic polyurethanes designed for non-viral cancer gene therapy

Nano-polyplexes from bioreducible cationic polymers have a massive promise for cancer gene therapy. However, the feasibility of cationic polyurethanes for non-viral gene therapy is so far not well studied. In this work, a linear cationic polyurethane containing disulfide bonds, urethane linkages and protonable tertiary amino groups was successfully generated by stepwise polycondensation reaction between 2,2'-dithiodiethanol bis(p-nitrophenyl carbonate) and 1,4-bis(3-aminopropyl)piperazine (BAP). We confirmed that the cationic polyurethane (denoted as PUBAP) displayed superior gene delivery properties to its cationic polyamide analogue, thus causing higher in vitro transfection efficiency in MCF-7 and SKOV-3 cells. Besides, further folate-PEGylation and hydrophobic deoxycholic acid (DCA) conjugation to amino-containing PUBAP can be conducted to afford multifunctional polyurethane gene delivery system. After optimization, folate-decorated nano-polyplexes from the PUBAP conjugated with 8 folate-PEG chains and 12 DCA residues exhibited superb colloidal stability under physiological conditions, and performed rapid uptake via folate receptor-mediated endocytosis, efficient intracellular gene release and nucleus translocation into SKOV-3 cells in vitro and in vivo. Importantly, PUBAP based polyplexes possess low cytotoxicity as a result of PUBAP biodegradability. Therefore, marked growth inhibition of SKOV-3 tumor xenografted in Balb/c nude mice was achieved with negligible side effects on the mouse health after intravenous administration of PUBAP based polyplexes with a therapeutic plasmid encoding for TNF-related apoptosis-inducing ligand. This work provides a new insight into biomedical application of bio-responsive polyurethanes for cancer therapy.

STATEMENT OF SIGNIFICANCE

In this study, we have confirmed that disulfide-based cationic polyurethane presents a new non-viral vector for gene transfer and cancer gene therapy. The significance of this work includes: (1) design and synthesis of a group of novel disulfide-based cationic polyurethane by non-isocyanate chemistry; (2) comparative study of transfection activity between cationic polyurethanes and cationic polyamides; (3) feasibility of bioreducible cationic polyurethanes for in vivo cancer gene therapy.

UPRT, a suicide-gene therapy candidate in higher eukaryotes, is required for Drosophila larval growth and normal adult lifespan

Uracil phosphoribosyltransferase (UPRT) is a pyrimidine salvage pathway enzyme that catalyzes the conversion of uracil to uridine monophosphate (UMP). The enzyme is highly conserved from prokaryotes to humans and yet phylogenetic evidence suggests that UPRT homologues from higher-eukaryotes, including Drosophila, are incapable of binding uracil. Purified human UPRT also do not show any enzymatic activity in vitro, making microbial UPRT an attractive candidate for anti-microbial drug development, suicide-gene therapy, and cell-specific mRNA labeling techniques. Nevertheless, the enzymatic site of UPRT remains conserved across the animal kingdom indicating an in vivo role for the enzyme. We find that the Drosophila UPRT homologue, krishah (kri), codes for an enzyme that is required for larval growth, pre-pupal/pupal viability and long-term adult lifespan. Our findings suggest that UPRT from all higher eukaryotes is likely enzymatically active in vivo and challenges the previous notion that the enzyme is non-essential in higher eukaryotes and cautions against targeting the enzyme for therapeutic purposes. Our findings also suggest that expression of the endogenous UPRT gene will likely cause background incorporation when using microbial UPRT as a cell-specific mRNA labeling reagent in higher eukaryotes.

A family of cationic polyamides for in vitro and in vivo gene transfection

The purpose of this study is to develop biodegradable cationic polyamides for non-viral gene delivery and elucidate their structural effects on gene transfection activity. To this end, a group of novel cationic polyamides were synthesized by polycondensation reaction between different di-p-nitrophenyl esters and tertiary amine-containing primary diamines. These linear polyamides have flexible alkylene group (ethylene or propylene), protonable amino group and bioreducible disulfide linkage in the polyamide main chain. The alkylene group and disulfide linkage in these polyamides have a distinct effect on their gene delivery properties including buffering capacity, gene binding ability and intracellular gene release profile. Those cationic polyamides containing disulfide linkage and 1,4-bis(3-aminopropyl)piperazine (BAP) residue exhibited high buffering capacity (endosomal escape ability), high gene binding ability, and intracellular gene release ability, thus inducing fast gene nucleus translocation and robust gene transfection in vitro against different cell lines and rat bone marrow mesenchymal stem cells. Moreover, the transfection efficiencies in vitro were comparable or higher than those of 25 kDa branched polyethylenimine and Lipofectamine 2000 transfection agent as positive controls. These cationic polyamides and their polyplexes were of low cytotoxicity when an optimal transfection efficacy was achieved. In vivo transfection tests showed that bioreducible BAP-based polyamides were applicable for intravenous gene delivery in a mouse model, leading to higher level of transgene expression in the liver as compared to 22 kDa linear polyethylenimine as a positive control. These cationic polyamides provide a useful platform to elucidate the relationship between chemical functionalities and gene transfection activity.

An Enterovirus-Like RNA Construct for Colon Cancer Suicide Gene Therapy

Background:

In gene therapy, the use of RNA molecules as therapeutic agents has shown advantages over plasmid DNA, including higher levels of safety. However, transient nature of RNA has been a major obstacle in application of RNA in gene therapy.

Methods:

Here, we used the internal ribosomal entry site of encephalomyocarditis virus and the 3’ non-translated region of Poliovirus to design an enterovirus-like RNA for the expression of a reporter gene (enhanced green fluorescent protein) and a suicide gene (thymidine kinase of herpes simplex virus). The expression of these genes was evaluated by flow cytometry and cytotoxicity assay in human colorectal adenocarcinoma cell line (SW480). We then armed RNA molecules with a target sequence for hsa-miR-143 to regulate their expression by microRNA (miRNA) mimics.

Results:

The results showed effective expression of both genes by Entrovirus-like RNA constructs. The data also showed that the restoration of hsa-miR-143 expression in SW480 leads to a significant translation repression of the introduced reporter and suicide genes.

Conclusion:

Collectively, our data suggest the potential use of Entrovirus-like RNA molecules in suicide gene therapy. Additionally, as a consequence of the possible downregulated miRNA expression in cancerous tissues, a decreased expression of gene therapy constructs armed with target sequences for such miRNA in cancer tissue is expected.

Arming oncolytic viruses to leverage antitumor immunity

INTRODUCTION

Over the past decade, the cytolytic capabilities of oncolytic viruses (OVs), exploited to selectively eliminate neoplastic cells, have become secondary to their use to elicit a tumor-directed immune response.

AREAS COVERED

Here, based on an NCBI-PubMed literature survey, we review the efforts undertaken to arm OVs in order to improve therapeutic antitumor responses upon administration of these agents. Specifically, we explore the different options to modulate immune suppression in the tumor microenvironment (TME) and to facilitate the generation of effective antitumor responses that have been investigated in conjunction with OVs in recent years.

EXPERT OPINION

Their induction of immunogenic tumor cell death and association with pro-inflammatory signals make OVs attractive immunotherapeutic modalities. The first promising clinical results with immunologically armed OVs warrant their further optimization and development. OVs should be modified to avoid detrimental effects of pre-existent anti-OV immunity as well as for increased tumor targeting and selectivity, so as to ultimately allow for systemic administration while achieving local immune potentiation and tumor elimination in the TME. In particular, a combination of trans-genes encoding bispecific T-cell engagers, immune checkpoint blockers and antigen-presenting cell enhancers will remove suppressive hurdles in the TME and allow for optimal antitumor efficacy of armed OVs.

MicroRNAs and oncolytic viruses

MicroRNAs regulate gene expression in mammalian cells and often exhibit tissue-specific expression patterns. Incorporation of microRNA target sequences can be used to control exogenous gene expression and viral tropism in specific tissues to enhance the therapeutic indices of oncolytic viruses expressing therapeutic transgenes. Continued development of this targeting strategy has resulted in the generation of unattenuated oncolytic viruses with enhanced potency, broad species-tropisms and reduced off-target toxicities in multiple-tissues simultaneously. Furthermore, oncolytic viruses have been used to enhance the delivery, duration and therapeutic efficacy of microRNA-based therapeutics designed to either restore or inhibit the function of dysregulated microRNAs in cancer cells. Recent efforts focused on combining oncolytic virotherapy and microRNA regulation have generated increasingly potent and safe cancer therapeutics.

Bioreducible dextran–polyethylenimine conjugates regulate transgene expression distribution in vivo

Bioreducible dextran–polyethyleneimine conjugates induce high transgene expression largely in the tumor by adjusting the molecular weight of dextran.

Oncoleaking: Use of the Pore-Forming Clostridium perfringens Enterotoxin (CPE) for Suicide Gene Therapy

Suicide gene therapy has been shown to be very efficient in tumor eradication. Numerous suicide genes were tested in vitro and in vivo demonstrating their therapeutic potential in clinical trials. Apart from this, still growing efforts are made to generate more targeted and more effective suicide gene systems for cancer gene therapy. In this regard bacterial toxins are an alternative, which add to the broad spectrum of different suicide strategies. In this context, the claudin-targeted bacterial Clostridium perfringens enterotoxin (CPE) is an attractive new type of suicide oncoleaking gene, which as pore-forming protein exerts specific and rapid toxicity towards claudin-3- and -4-overexpressing cancers. In this chapter we describe the generation and use of CPE-expressing vectors for the effective tumor cell killing as novel suicide gene approach particularly for treatment of therapy refractory tumors.

Key points of basic theories and clinical practice in rAd-p53 ( Gendicine ™) gene therapy for solid malignant tumors

INTRODUCTION

Wild-type p53 gene is an essential cancer suppressor gene which plays an important role in carcinogenesis and malignant progressions. The p53 gene family participates in almost all the key procedures of cancer biology, such as programmed cell death, angiogenesis, metabolism and epithelial-mesenchymal transition. The mutation or functional defects of the p53 gene family are detected in most of the solid malignant tumors, and the restoration of the p53 gene by adenovirus-mediated gene therapy becomes a promising treatment for cancer patients now.

AREAS COVERED

In the present review, the potential therapeutic effects of recombinant adenovirus p53 rAd-p53 ( Gendicine ™) were reviewed to explore the biological mechanism underlying the adenovirus-mediated p53 gene therapy. Then, the key points of the drug administration were discussed, including the routes of administration, dosage calculation and treatment cycles, based on findings of the preclinical and clinical trials in order to establish a standard treatment for the p53 gene therapy.

EXPERT OPINION

As an important part of the combined therapy for the cancer patients, the adenovirus-mediated p53 gene therapy was blossomed to be a promising treatment strategy. A new evaluation criteria and guideline for the gene therapy is urgently needed for the further clinical practice.

Electrospun nanofibers as versatile interfaces for efficient gene delivery

The integration of gene delivery technologies with electrospun nanofibers is a versatile strategy to increase the potential of gene therapy as a key platform technology that can be readily utilized for numerous biomedical applications, including cancer therapy, stem cell therapy, and tissue engineering. As a spatial template for gene delivery, electrospun nanofibers possess highly advantageous characteristics, such as their ease of production, their ECM-analogue nature, the broad range of choices for materials, the feasibility of producing structures with varied physical and chemical properties, and their large surface-to-volume ratios. Thus, electrospun fiber-mediated gene delivery exhibits a great capacity to modulate the spatial and temporal release kinetics of gene vectors and enhance gene delivery efficiency. This review discusses the powerful characteristics of electrospun nanofibers, which can function as spatial interfaces capable of promoting controlled and efficient gene delivery.

Prognostic value of miR-26a and HMGA1 in urothelial bladder cancer

BACKGROUND

MicroRNA-26a (miR-26a) functions as a tumor suppressor by regulating its direct target gene high mobility group AT-hook 1 (HMGA1). This study was aimed to investigate the associations of differential expression of miR-26a and HMGA1 with tumor progression and prognosis in urothelial bladder cancer (UBC) patients.

MATERIALS AND METHODS

One hundred and twenty-six UBC patients were selected and quantitative real-time PCR was performed to detect the expression of miR-26a and HMGA1 mRNA in the respective tumors.

RESULTS

Our data showed the decreased expression of miR-26a and the increased expression of HMGA1 mRNA in UBC tissues compared with corresponding non-cancerous tissues (both P<0.001). Then, the expression levels of miR-26a in UBC tissues were negatively correlated with those of HMGA1 mRNA significantly (r=-0.72, P<0.001). In addition, UBC patients with combined miR-26a downregulation and HMGA1 upregulation (miR-26a-low/HMGA1-high) more frequently had advanced pathological stage (P<0.001) and high tumor grade (P<0.001). Moreover, miR-26a-low/HMGA1-high expression was associated with a significantly shortest disease-free survival (P<0.001) and overall survival (P<0.001) of all miR-26a/HMGA1 combined expression groups. Furthermore, multivariate analysis indicated that miR-26a/HMGA1 expression was an independent prognostic factor for both disease-free survival and overall survival (both P=0.001) in UBC patients.

CONCLUSION

Interaction between miR-26a and its target gene HMGA1 may contribute to the malignant progression of human UBC. Tumors with miR-26a downregulation in combination with high expression of HMGA1 showed a worse prognosis than the other tumors. Combined detection of their expression might be particularly helpful for surveillance of disease progression and treatment stratification.

Mesenchymal stem cells genetically modified by lentivirus-mediated interleukin-12 inhibit malignant ascites in mice

The objective of the present study was to investigate the effects of mesenchymal stem cells (MSCs) genetically modified by lentivirus-mediated mouse interleukin-12 (Lenti-mIL-12) in treating malignant ascites in mice. The in vitro chemotactic effect of Lenti-mIL-12-MSC culture supernatant on dendritic cells was investigated using a chemotaxis chamber. Liver cancer H22 and MethA ascites models were constructed. Mice were divided evenly into four groups: Normal saline, MSC, Null and Lenti-mIL-12-MSC. The survival rate, ascites volume and red blood cell number were measured for these groups. The toxicity and side effects of Lenti-mIL-12-MSCs were investigated using visual and microscopy inspections. The results indicated that mIL-12 had a strong chemotactic effect on dendritic cells. mIL-12 was highly expressed in ascites of Lenti-mIL-12-MSC-treated mice. Lenti-mIL-12-MSCs reduced the volume of ascites and the number of red blood cells in ascites and thus increased the survival rate and prolonged the survival duration of the mice. Furthermore, Lenti-mIL-12-MSCs showed no toxicity and side effects on the mice with malignant ascites. In conclusion, the results demonstrated that Lenti-mIL-12-MSCs inhibited the growth of ascites and promoted the survival of tumor-bearing mice, suggesting that Lenti-mIL-12-MSCs exerts a therapeutic effect on malignant ascites by stimulating the immune responses of the mice.

Trial Watch:: Oncolytic viruses for cancer therapy

Oncolytic viruses are natural or genetically modified viral species that selectively infect and kill neoplastic cells. Such an innate or exogenously conferred specificity has generated considerable interest around the possibility to employ oncolytic viruses as highly targeted agents that would mediate cancer cell-autonomous anticancer effects. Accumulating evidence, however, suggests that the therapeutic potential of oncolytic virotherapy is not a simple consequence of the cytopathic effect, but strongly relies on the induction of an endogenous immune response against transformed cells. In line with this notion, superior anticancer effects are being observed when oncolytic viruses are engineered to express (or co-administered with) immunostimulatory molecules. Although multiple studies have shown that oncolytic viruses are well tolerated by cancer patients, the full-blown therapeutic potential of oncolytic virotherapy, especially when implemented in the absence of immunostimulatory interventions, remains unclear. Here, we cover the latest advances in this active area of translational investigation, summarizing high-impact studies that have been published during the last 12 months and discussing clinical trials that have been initiated in the same period to assess the therapeutic potential of oncolytic virotherapy in oncological indications.