Non-viral vectors for cancer therapy

Technological advances in the use of viral and non-viral vectors for delivering genetic and non-genetic cargos for cancer therapy

The burden of cancer is increasing globally. Several challenges facing its mainstream treatment approaches have formed the basis for the development of targeted delivery systems to carry and distribute anti-cancer payloads to their defined targets. This site-specific delivery of drug molecules and gene payloads to selectively target druggable biomarkers aimed at inducing cell death while sparing normal cells is the principal goal for cancer therapy. An important advantage of a delivery vector either viral or non-viral is the cumulative ability to penetrate the haphazardly arranged and immunosuppressive tumour microenvironment of solid tumours and or withstand antibody-mediated immune response. Biotechnological approaches incorporating rational protein engineering for the development of targeted delivery systems which may serve as vehicles for packaging and distribution of anti-cancer agents to selectively target and kill cancer cells are highly desired. Over the years, these chemically and genetically modified delivery systems have aimed at distribution and selective accumulation of drug molecules at receptor sites resulting in constant maintenance of high drug bioavailability for effective anti-tumour activity. In this review, we highlighted the state-of-the art viral and non-viral drug and gene delivery systems and those under developments focusing on cancer therapy.

In vitro transfection efficiencies of T-shaped spermine-based cationic lipids with identical and nonidentical tails under high serum conditions

T-shaped spermine-based cationic lipids with identical and nonidentical hydrophobic tails having variable carbon lengths (from C10 to C18) were designed and synthesized. These lipids were characterized, and their structure-activity relationships were determined for DNA binding and transfection ability of these compounds when formulated as cationic liposomes. These liposomes were then applied as non-viral vectors to transfect HEK293T, HeLa, PC3, H460, HepG2, and Calu'3 cell lines with plasmid DNA encoding the green fluorescent protein. ST9, ST12 and ST13 with nonidentical tails could deliver DNA into HEK293T cells up to 60% under serum-free conditions. The lipid ST15 bearing nonidentical tails was found to be a potent gene transfer agent under 40% serum conditions in HEK293T and HeLa cells. Besides their low cytotoxicity, these lipoplexes also exhibited greater transfection efficiency than the commercially available transfection agent, Lipofectamine 3000.

Targeted Liposomes: A Nonviral Gene Delivery System for Cancer Therapy

Cancer is the second most frequent cause of death worldwide, with 28.4 million new cases expected for 2040. Despite de advances in the treatment, it remains a challenge because of the tumor heterogenicity and the increase in multidrug resistance mechanisms. Thus, gene therapy has been a potential therapeutic approach owing to its ability to introduce, silence, or change the content of the human genetic code for inhibiting tumor progression, angiogenesis, and metastasis. For the proper delivery of genes to tumor cells, it requires the use of gene vectors for protecting the therapeutic gene and transporting it into cells. Among these vectors, liposomes have been the nonviral vector most used because of their low immunogenicity and low toxicity. Furthermore, this nanosystem can have its surface modified with ligands (e.g., antibodies, peptides, aptamers, folic acid, carbohydrates, and others) that can be recognized with high specificity and affinity by receptor overexpressed in tumor cells, increasing the selective delivery of genes to tumors. In this context, the present review address and discuss the main targeting ligands used to functionalize liposomes for improving gene delivery with potential application in cancer treatment.

Serum Compatible Spermine-based Cationic Lipids with Non-identical Hydrocarbon Tails Mediate High Transfection Efficiency

Cationic lipids are widely used as non-viral synthetic vectors for gene delivery as a safer alternative to viral vectors. In this work, a library of L-shaped spermine-based cationic lipids with identical and non-identical hydrophobic chains having variable carbon length (from C10 to C18) was designed and synthesized. These lipids were characterized and the structure-activity relationships of these compounds were determined for DNA binding and transfection ability when formulated as cationic liposomes. The liposomes were then used successfully for the transfection of HEK293T, HeLa, PC3, H460, HepG2, SH-SY5Y and Calu'3 cell lines. The transfection efficiency of lipids with non-identical hydrocarbon chains was greater than the identical analog. These reagents exhibited superior efficiency to the commercial reagent, Lipofectamine3000, under both serum-free and 10-40% serum conditions in HEK293T, HeLa and H460 cell lines. The lipids were also not toxic to the tested cells. The results suggested that L-shaped spermine-based cationic lipids with non-identical hydrocarbon tails could serve as an efficient and safe non-viral vector gene carrier for further in vivo studies.

Engineering Circulating Tumor Cells as Novel Cancer Theranostics

New ways to target and treat metastatic disease are urgently needed. Tumor “self-homing” describes the recruitment of circulating tumor cells (CTCs) back to a previously excised primary tumor location, contributing to tumor recurrence, as well as their migration to established metastatic lesions. Recently, self-homing CTCs have been exploited as delivery vehicles for anti-cancer therapeutics in preclinical primary tumor models. However, the ability of CTCs to self-home and treat metastatic disease is largely unknown.

Methods: Here, we used bioluminescence imaging (BLI) to explore whether systemically administered CTCs home to metastatic lesions and if CTCs armed with both a reporter gene and a cytotoxic prodrug gene therapy can be used to visualize and treat metastatic disease.

Results: BLI performed over time revealed a remarkable ability of CTCs to home to and treat tumors throughout the body. Excitingly, metastatic tumor burden in mice that received therapeutic CTCs was lower compared to mice receiving control CTCs.

Conclusion: This study demonstrates the noteworthy ability of experimental CTCs to home to disseminated breast cancer lesions. Moreover, by incorporating a prodrug gene therapy system into our self-homing CTCs, we show exciting progress towards effective and targeted delivery of gene-based therapeutics to treat both primary and metastatic lesions.

Oncolytic virus therapy in Japan: progress in clinical trials and future perspectives

Oncolytic virus therapy is a promising new option for cancer. It utilizes genetically engineered or naturally occurring viruses that selectively replicate in and kill cancer cells without harming normal cells. T-VEC (talimogene laherparepvec), a second-generation oncolytic herpes simplex virus type 1, was approved by the US Food and Drug Administration for the treatment of inoperable melanoma in 2015 and subsequently approved in Europe in 2016. Other oncolytic viruses using different parental viruses have also been tested in Phase III clinical trials and are ready for drug approval: Pexa-Vec (pexastimogene devacirepvec), an oncolytic vaccinia virus, CG0070, an oncolytic adenovirus, and REOLYSIN (pelareorep), an oncolytic reovirus. In Japan, as of May 2018, several oncolytic viruses have been developed, and some have already proceeded to clinical trials. In this review, we summarize clinical trials assessing oncolytic virus therapy that were conducted or are currently ongoing in Japan, specifically, T-VEC, the abovementioned oncolytic herpes simplex virus type 1, G47Δ, a third-generation oncolytic herpes simplex virus type 1, HF10, a naturally attenuated oncolytic herpes simplex virus type 1, Telomelysin, an oncolytic adenovirus, Surv.m-CRA, another oncolytic adenovirus, and Sendai virus particle. In the near future, oncolytic virus therapy may become an important and major treatment option for cancer in Japan.

Cationic cholesterol derivative efficiently delivers the genes: in silico and in vitro studies

The aims of the research work were to synthesize ethyl(cholesteryl carbamoyl)-L-arginate (ECCA), an arginine-conjugated cholesterol derivative, and to evaluate its application as a gene delivery vector. The interactions of ECCA with DNA duplex were studied using molecular dynamics (MD) simulations. It was found that the guanidine group of ECCA could interact with the phosphate group of DNA through ionic interactions as well as hydrogen bonds. The structure of DNA was stable throughout the simulation time. Liposomes were formulated using ECCA and soya phosphatidylcholine (SPC) by a thin-film hydration method. They had the particle size of ~ 150 nm and the zeta potential of + 51 mV. To ensure the efficient binding of DNA to the liposomes, the ratio of DNA to ECCA was optimized using gel retardation assay. Further, serum stability, haemolysis and cytotoxicity studies were carried out to determine the stability and safety of the lipoplexes. Circular dichroism spectroscopy was used to determine the interaction of DNA and cationic liposomes. Cellular uptake pathway was determined by studying the uptake of coumarin-loaded lipoplexes at 4 °C and in the presence of uptake inhibitors, i.e. genistein, chlorpromazine and methyl-β-cyclodextrin. Transfection studies were carried out to evaluate the transfection efficacy of the ECCA-loaded lipoplexes. The binding of DNA and lipoplexes was found to be stable in the presence of serum, and no degradation of DNA was observed. The lipoplexes showed low haemolysis and cytotoxicity. The uptake of coumarin-loaded liposomes was decreased up to ~ 20% in the presence of clathrin- and caveola-mediated uptake inhibitors, indicating a role of both the pathways in the uptake of the inhibitors. Satisfactory transfection efficiency was obtained compared to Lipofectamine^®. Thus, cationic cholesterol derivative is a useful tool for gene delivery vector.

A novel method for conjugating the terminal amine of peptide ligands to cholesterol: synthesis iRGD-cholesterol

AIM

Conventional conjugation reactions often involve the use of activated PEG as a linker, but concerns about PEG-mediated reduction in intracellular delivery and enhanced immunogenicity have generated interest in developing methods that eliminate the need for a PEG linker.

MATERIALS & METHODS

Reaction conditions were identified that specifically couples the terminal amine of a cyclic iRGD peptide (CRGDRGPDC) to the hydroxyl moiety of cholesterol through a short carbamate linker.

RESULTS & CONCLUSION

Using this method for synthesizing iRGD-cholesterol, peptide ligands can be incorporated into lipid-based delivery systems, thereby eliminating concerns about adverse reactions to PEG. Toxicity and stability data indicate low toxicity and adequate serum stability at low ligand levels.

Overexpression of Rad51 Predicts Poor Prognosis in Colorectal Cancer: Our Experience with 54 Patients

BACKGROUND

Aberrant Rad51 expression is implicated in the progression of human malignancies. However, the role of Rad51 in colorectal cancer (CRC) remains undefined. This study aimed to establish a relationship between Rad51 and clinicopathologic features of CRC.

METHODS

We retrospectively examined the paraffin-embedded tissue samples obtained from 54 patients with CRC who had received surgical therapies at our institution during 2006-2008. Rad51 expression in adenocarcinoma, paracancerous tissue, and normal colonic tissue was determined by immunohistochemistry. The correlation between Rad51 immunoreactivity and clinicopathologic features of these patients was evaluated.

RESULTS

Rad51 immunoreactivity was detected in 67% of adenocarcinoma, 48% of paracancerous tissue, and 27% of normal colonic mucosa. Rad51 expression in adenocarcinoma was significantly higher than normal colonic tissue (p < 0.05). Rad51 was also overexpressed in poorly differentiated tumors and tumor samples from patients with lymph node metastasis (p < 0.05). Patients with Rad51 overexpression had a 69% two-year survival, 49% three-year survival, and 16% five-year survival, considerably worse than patients with negative Rad51 expression (p < 0.05).

CONCLUSION

Our data suggest that Rad51 overexpression is correlated with malignant phenotypes of CRC and may predict poor prognosis for these patients.

Viral gene therapy for head and neck cancer

BACKGROUND

Viral gene therapy is a promising new treatment modality for head and neck cancer. This paper provides the reader with a review of the relevant literature in this field.

RESULTS

There are government licensed viral gene therapy products currently in use for head and neck cancer, utilised in conjunction with established treatment modalities. The viruses target tumour-associated genes, with the first licensed virus replacing p53 gene function, which is frequently lost in tumourigenesis. Oncolytic viruses selectively destroy cancer cells through viral replication and can be armed with therapeutic transgenes.

CONCLUSION

Despite considerable advances in this field over the last 40 years, further research is needed to improve the overall efficacy of the viruses and allow their widespread utilisation in the management of head and neck cancer.

Antitumor and antimetastasis effects of carboplatin liposomes with polyethylene glycol-2000 on SGC-7901 gastric cell-bearing nude mice

The present study aimed to analyze the characteristics of polyethylene glycol (PEG)ylated carboplatin liposomes (PL-CBPs), including size, stability, their release, entrapping and loading efficiencies, and their antitumor and antimetastatic effects on the lymph nodes. The PL-CBPs were prepared using PEG-2000 with the thin film hydration method. The liposome size and release, entrapping and loading efficiencies were detected by ultra-violet/visible spectrophotometry. A nude mouse model was established with the SGC-7901 gastric cell line to evaluate the antitumor effect of the PL-CBP. After 7 days, the mice were randomly divided into three groups (the control, CBP, and PL-CBP groups). CBP and PL-CBP were administered at a dose of 10 mg/kg for two consecutive cycles of treatment, 5 days apart, to their respective groups. In each group, two doses of 5 mg/kg were administered every 48 h. The tumor weight and volume were detected, and the food intake and body weight were measured during the administration. Apoptosis in the tumor cells was evaluated by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling and platinum (Pt) accumulation was detected by atomic absorption spectroscopy. Lastly, lymph node metastasis was evaluated by hematoxylin and eosin staining. The PL-CBPs were more stable when comapred with CBP alone, and the drug release efficiency was 0.7, 22.5, 48.7 and 65.1% at 37°C for 0, 12, 24 and 48 h. The results showed that the encapsulation efficiency was 85% and the loading efficiency was 0.15 mg/mg lipid. After 35 days, PL-CBP induced potent antitumor effects compared with the control and CBP groups (PL-CBP vs. control, P<0.01; PL-CBP vs. CBP, P<0.05). PL-CBP and CBP induced a lower and the lowest body weight and level of food intake, respectively, compared with the control group (CBP vs. control, P<0.05). The apoptosis rate and lymph node metastasis in the PL-CBP group was higher than that in the CBP and control groups (PL-CBP vs. control, P<0.01; PL-CBP vs. CBP, P<0.05). Pt accumulation in the tumors was higher in the PL-CBP group than in the CBP group (PL-CBP vs. CBP, P<0.05). The PL-CBPs were more stable in the circulation and could be released more slowly at the tumor site than compared with CBP injection. The PL-CBPs showed potent antitumor and antimetastatic effects on the lymph nodes.

Efficient delivery of plasmid DNA using cholesterol-based cationic lipids containing polyamines and ether linkages

Cationic liposomes are broadly used as non-viral vectors to deliver genetic materials that can be used to treat various diseases including cancer. To circumvent problems associated with cationic liposome-mediated delivery systems such as low transfection efficiency and serum-induced inhibition, cholesterol-based cationic lipids have been synthesized that resist the effects of serum. The introduction of an ether-type linkage and extension of the aminopropyl head group on the cholesterol backbone increased the transfection efficiency and DNA binding affinity compared to a carbamoyl-type linkage and a mono aminopropyl head group, respectively. Under optimal conditions, each liposome formulation showed higher transfection efficiency in AGS and Huh-7 cells than commercially available cationic liposomes, particularly in the presence of serum. The following molecular structures were found to have a positive effect on transfection properties: (i) extended aminopropyl head groups for a strong binding affinity to plasmid DNA; (ii) an ether linkage that favors electrostatic binding to plasmid DNA; and (iii) a cholesterol backbone for serum resistance.

Histidinylated poly-L-lysine-based vectors for cancer-specific gene expression via enhancing the endosomal escape

In this work, we synthesized a series of poly-L-lysine (PLL)-based polymers for gene delivery, by modifying the PLL with both cationic peptide and histidine. The peptide moieties serve as cationic centers for polyplex formation, and also as substrates for protein kinase Cα (PKCα), which is specifically activated in many types of cancer cells, to achieve cancer-specific gene expression. The histidine groups serve as buffering moieties to increase the ability of the plasmid DNA (pDNA)-polymer complex (polyplex) to escape the endosome and thus to promote expression of the pDNA in the transfected cells. The facile synthesis of the polymers proceeded by modifying the PLL with side-group-protected peptide and protected histidine, followed by deprotection of the functional groups. The synthesized polymers showed significant buffering capacity over the neutral to acidic pH range and showed less cytotoxicity in vitro compared with histidine-unmodified polymers. The polyplexes successfully showed PKCα-responsive gene expression immediately after their introduction into cancer cells and the gene expression continued for at least 24 h. These PLL-based carriers thus show promise for cancer-targeted gene therapy.

Gene therapy, early promises, subsequent problems, and recent breakthroughs

Gene therapy is one of the most attractive fields in medicine. The concept of gene delivery to tissues for clinical applications has been discussed around half a century, but scientist's ability to manipulate genetic material via recombinant DNA technology made this purpose to reality. Various approaches, such as viral and non-viral vectors and physical methods, have been developed to make gene delivery safer and more efficient. While gene therapy initially conceived as a way to treat life-threatening disorders (inborn errors, cancers) refractory to conventional treatment, to date gene therapy is considered for many non-life-threatening conditions including those adversely influence on a patient's quality of life. Gene therapy has made significant progress, including tangible success, although much slower than was initially predicted. Although, gene therapies still at a fairly primitive stage, it is firmly science based. There is justifiable hope that with enhanced pathobiological understanding and biotechnological improvements, gene therapy will be a standard part of clinical practice within 20 years.

Update on oncolytic viral therapy - targeting angiogenesis

Oncolytic viruses (OVs) have the ability to selectively replicate in and lyse cancer cells. Angiogenesis is an essential requirement for tumor growth. Like OVs, the therapeutic effect of many angiogenesis inhibitors has been limited, leading to the development of more effective approaches to combine antiangiogenic therapy with OVs. Angiogenesis can be targeted either directly by OV infection of vascular endothelial cells, or by arming OVs with antiangiogenic transgenes, which are subsequently expressed locally in the tumor microenvironment. In this review, we describe the development and targeting of OVs, the role of angiogenesis in cancer, and the progress made in arming viruses with antiangiogenic transgenes. Future developments required to optimize this approach are addressed.

The use of isothermal titration calorimetry and molecular dynamics to show variability in DNA transfection performance

The mechanism causing variability in DNA transfection efficacy for low-molecular-weight pDMAEMA (poly(2-(dimethylamino)ethyl methacrylate) and pDMAEMA-b-pHEMA (poly(2-(dimethyl amino)ethylmethacrylate)-block-poly(2-hydroxyl methacrylate)) has so far remained unclear, apart from the evidence of beneficial effects of the pHEMA grafting. This study has explicitly characterized the electrostatically driven self-assembly process of linear polymethacrylate polymers with DNA-generating nanocarriers for efficient gene transfection. Isothermal titration calorimetry (ITC) showed clear differences in binding-heat profiles of homo-polycationic and pHEMA grafted polymers with DNA. Polyethylene imine, a branched polycationic polymer of 25kDa with high transfection potential that has previously been successfully used in transfection experiments, demonstrated a heat flow profile that was partly identical to pDMAEMA-b-pHEMA. Computational molecular dynamics (MD) simulated the folding process of polymer in water from a linear to a coiled state: homo-pDMAEMA and pHEMA grafts reduced their overall positive charge accessibility upon folding, down to 45% and 63%, respectively. The homo-pDMAEMA formed the globular conformation more preferably than pHEMA grafts, thus impeding electrostatic interaction with DNA. These findings substantiate the known disadvantage of low-molecular-weight linear polymers compared to higher-molecular-weight polymers in transfection performance; here we have disclosed the ability of a non-cationic chain elongation to be beneficial for the self-assembly process. The combination of MD and ITC has proved to be a suitable approach for carrier-payload interaction studies and may be used to predict the efficacy of a polymer as a nanocarrier from the flexibility of its structure.

A rapid and convenient method to enhance transgenic expression in target cells

Gene therapy provides a novel strategy and a new hope for patients with cancer. Unfortunately, the specifics of the delivery systems or the promoters have not achieved the specified efficacy so far, and the perfection of either system will be extremely difficult. In this study, we introduce a simple concept that a combination of a partially specific delivery system and a partially specific promoter activity may achieve a more specific effect on transgenic expression in target cells. The first section describes tumor-related transcription factors that were assayed in tumors or rapidly proliferating cells to determine their activities. The activities of nuclear factor (NF)-κB, CREB, and HIF-1 were higher, and three copies of each response element were used to construct a transcription factor-based synthetic promoter (TSP). The results showed that the expression of the TSP was active and partially specific to cell types. As described in the second section, the multifunctional peptide RGD-4C-HA was designed to absorb polyethyleneimine (PEI) molecules, and this complex was targeted to integrin αvβ3 on B16F10 cells. The results indicated that RGD-4C-HA could associate with PEI to mediate specific targeting in vitro. Finally, the combination of the PEI-peptide complex and TSP could enhance the specifically transgenic expression in B16F10 cells. This strategy has been proven to work in vitro and might potentially be used for specific gene therapy in vivo.

Fabrication of functionalized double-lamellar multifunctional envelope-type nanodevices using a microfluidic chip with a chaotic mixer array

Multifunctional envelope-type nanodevices (MENDs) are very promising non-viral gene delivery vectors because they are biocompatible and enable programmed packaging of various functional elements into an individual nanostructured liposome. Conventionally MENDs have been fabricated by complicated, labor-intensive, time-consuming bulk batch methods. To avoid these problems in MEND fabrication, we adopted a microfluidic chip with a chaotic mixer array on the floor of its reaction channel. The array was composed of 69 cycles of the staggered chaotic mixer with bas-relief structures. Although the reaction channel had very large Péclet numbers (>10(5)) favorable for laminar flows, its chaotic mixer array led to very small mixing lengths (<1.5 cm) and that allowed homogeneous mixing of MEND precursors in a short time. Using the microfluidic chip, we fabricated a double-lamellar MEND (D-MEND) composed of a condensed plasmid DNA core and a lipid bilayer membrane envelope as well as the D-MEND modified with trans-membrane peptide octaarginine. Our lab-on-a-chip approach was much simpler, faster, and more convenient for fabricating the MENDs, as compared with the conventional bulk batch approaches. Further, the physical properties of the on-chip-fabricated MENDs were comparable to or better than those of the bulk batch-fabricated MENDs. Our fabrication strategy using microfluidic chips with short mixing length reaction channels may provide practical ways for constructing more elegant liposome-based non-viral vectors that can effectively penetrate all membranes in cells and lead to high gene transfection efficiency.

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.

Eukaryotic expression vectors bearing genes encoding cytotoxic proteins for cancer gene therapy

Cancer gene therapy is a promising direction for the treatment of cancer patients. A primary goal of all cancer therapies is to selectively target and kill tumour cells. Such therapies are administered via different approaches, including both viral and non-viral delivery; however, both methods have advantages and disadvantages. Transcriptional targeting enables genes encoding toxic proteins to be expressed directly in cancer cells. Numerous vectors have been created with the purpose of killing cancer cells, and some have successfully suppressed malignant tumours. Data concerning the function of vectors bearing genes that encode cytotoxic proteins under the control of different promoters, including tissue/tumour specific and constitutive promoters, is summarised here. This review focuses on vectors that bear genes encoding diphtheria toxin, Pseudomonas exotoxin A, caspases, gef, streptolysin, and melittin. Data describing the efficacy of such vectors have been summarised. Notably, there are vectors that killed cancer cell lines originating from the same type of cancer with differential efficiency. Thus, there is differential inhibition of cancer cell growth dependent on the cell line. In this review, the constructs employing genes whose expression induces cell death and the efficiency with which they suppress cancer cell growth will be summarised.

Bilayer matrix composed of polycation/DNA complex and sodium alginate gel as a tumor cell catcher

A bilayer matrix consisting of TABP-SS/DNA complexes and sodium alginate gel is formed via electrostatic interaction. In vitro cell adhesion, proliferation and transfection of the bilayer matrix are investigated in HepG2, HeLa and COS7 cells. Results show that this matrix can only promote tumor cell attachment and growth. Compared with normal cells, the bilayer matrix exhibits significantly higher transfection efficacy in tumor cells. Cell co-culture competitive transfection assay shows that the cell uptake of TABP-SS/DNA complexes is significantly enhanced in tumor cells rather than normal cells under the co-culture competitive condition, which confirms that TABP-SS/DNA complexes have strong tumor cell selectivity and tumor targeting transfection ability.

Effects of poly(lactic-co-glycolic acid) on preparation and characteristics of plasmid DNA-loaded solid lipid nanoparticles

Poly(lactic-co-glycolic acid) (PLGA) was used as a polymeric emulsifier to encapsulate plasmid DNA into hydrogenated castor oil (HCO)-solid lipid nanoparticles (SLN) by w/o/w double emulsion and solvent evaporation techniques. The effects of PLGA on the preparation, characteristics and transfection efficiency of DNA-loaded SLN were studied. The results showed that PLGA was essential to form the primary w/o emulsion and the stability of the emulsion was enhanced with the increase of PLGA content. DNA-loaded SLN were spherical with smooth surfaces. The SLN had a negative charge in weak acid and alkaline environment but acquired a positive charge in acidic pH and the cationisation capacity of the SLN increased with the increase of PLGA/HCO ratio. Agarose gel electrophoresis demonstrated that the majority of the DNA maintained its structural integrity after preparation and being extracted or released from DNA-loaded SLN. When PLGA/HCO ratio increased from 5 to 15%, the encapsulation efficiency, loading capacity and transfection efficiency of the nanoparticles increased significantly, whereas the changes of particle size and polydispersity index were insignificant. Cytotoxicity study in cell culture demonstrated that the SLN was not toxic.

Lipothioureas as Lipids for Gene Transfection: A Review

Non-viral gene therapy requires innovative strategies to achieve higher transfection efficacy. A few years ago, our group proposed bioinspired lipids whose interaction with DNA was not based on ionic interactions, but on hydrogen bonds. We thus developed lipids bearing a thiourea head which allowed an interaction with DNA phosphates through hydrogen bonds. After a proof of concept with a lipid bearing three thiourea functions, a molecular and cellular screening was performed by varying all parts of the lipids: the hydrophobic anchor, the spacer, the linker, and the thiourea head. Two lipothiourea-based structures were identified as highly efficient in vitro transfecting agents. The lipothioureas were shown to reduce non specific interactions with cell membranes and deliver their DNA content intracellularly more efficiently, as compared to cationic lipoplexes. These lipids could deliver siRNA efficiently and allowed specific cell targeting in vitro. In vivo, thiourea lipoplexes presented a longer retention time in the blood and less accumulation in the lungs after an intravenous injection in mice. They also induced luciferase gene expression in muscle and tumor after local administration in mice. Therefore, these novel lipoplexes represent an excellent alternative to cationic lipoplexes as transfecting agents. In this review we will focus on the structure activity studies that permitted the identification of the two most efficient thiourea lipids.

Linking transgene expression of engineered mesenchymal stem cells and angiopoietin-1-induced differentiation to target cancer angiogenesis

OBJECTIVE

To specifically target tumor angiogenesis by linking transgene expression of engineered mesenchymal stem cells to angiopoietin-1-induced differentiation.

BACKGROUND

Mesenchymal stem cells (MSCs) have been used to deliver therapeutic genes into solid tumors. These strategies rely on their homing mechanisms only to deliver the therapeutic agent.

METHODS

We engineered murine MSC to express reporter genes or therapeutic genes under the selective control of the Tie2 promoter/enhancer. This approach uses the differentiative potential of MSCs induced by the tumor microenvironment to drive therapeutic gene expression only in the context of angiogenesis.

RESULTS

When injected into the peripheral circulation of mice with either, orthotopic pancreatic or spontaneous breast cancer, the engineered MSCs were actively recruited to growing tumor vasculature and induced the selective expression of either reporter red florescent protein or suicide genes [herpes simplex virus-thymidine kinase (TK) gene] when the adoptively transferred MSC developed endothelial-like characteristics. The TK gene product in combination with the prodrug ganciclovir (GCV) produces a potent toxin, which affects replicative cells. The homing of engineered MSC with selective induction of TK in concert with GCV resulted in a toxic tumor-specific environment. The efficacy of this approach was demonstrated by significant reduction in primary tumor growth and prolongation of life in both tumor models.

CONCLUSION

This "Trojan Horse" combined stem cell/gene therapy represents a novel treatment strategy for tailored therapy of solid tumors.

Advancement and prospects of tumor gene therapy

Gene therapy is one of the most attractive fields in tumor therapy. In past decades, significant progress has been achieved. Various approaches, such as viral and non-viral vectors and physical methods, have been developed to make gene delivery safer and more efficient. Several therapeutic strategies have evolved, including gene-based (tumor suppressor genes, suicide genes, antiangiogenic genes, cytokine and oxidative stress-based genes) and RNA-based (antisense oligonucleotides and RNA interference) approaches. In addition, immune response-based strategies (dendritic cell- and T cell-based therapy) are also under investigation in tumor gene therapy. This review highlights the progress and recent developments in gene delivery systems, therapeutic strategies, and possible clinical directions for gene therapy.

Gene transfer to the mammalian reproductive tract

This review summarizes the results of research on gene transfer to the mammalian genital tract. Gene transfer experiments have been developed during the last 2 decades and have been applied using in vitro, ex vivo and in vivo procedures. (i) In vitro methods have been applied to the uterine epithelial cells with the principal purpose of analysing some pathological change occurring in the uterus. In the male tract, epididymal cell lines have been used to evaluate the expression of particular genes and the function of specific proteins. (ii) Ex vivo methods have been applied to both the uterus and the vas deferens in humans, and good transgene expression has been recorded. (iii) In vivo gene transfer in the female tract has been employed in the uterus and oviduct using gene injections or electroporation methods. The glandular epithelium of both organs can be transfected efficiently, and transfection efficiency depends on the hormonal stage of the animal. The best expression occurred during pseudopregnancy and meta-estrus periods, when high progesterone and low estradiol concentrations occur. In the male tract, in vivo methods have been applied to mouse vas deferens and epididymis. In both organs, patches of epithelial regions appeared to express the transgenes. Furthermore, the secretions of both organs were also modified using gene constructions that led to the expression of some secretory proteins. In summary, gene modifications in the epithelium of the mammalian reproductive tract have been successful employing different technologies. Further improvements in transfection efficiency would help provide new insights into the physiology of these reproductive organs. Furthermore, the use of these methods could also be used to modify the fertility of mammals.

Update on non-viral delivery methods for cancer therapy: possibilities of a drug delivery system with anticancer activities beyond delivery as a new therapeutic tool

IMPORTANCE OF THE FIELD

Cancer is the most formidable human disease. Owing 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 for cancer therapy. These therapeutic agents should be carefully selected to enhance multiple therapeutic pathways. Non-viral delivery methods have been utilized to enhance the tumor-selective delivery of therapeutic molecules, including proteins, synthetic oligonucleotides, small compounds and genes.

AREAS COVERED IN THIS REVIEW

As non-viral delivery methods, liposomes and polymer-based delivery materials to target tumors mainly by systemic delivery, physical methods including electroporation, sonoporation, and so on, to locally inject therapeutic molecules, and virosomes to use the viral infectious machinery for the delivery of therapeutic molecules are summarized.

WHAT THE READER WILL GAIN

This article aims to provide an overview of the characteristic properties of each non-viral vector. It will be beneficial to utilize appropriately the vector for cancer treatment.

TAKE HOME MESSAGE

Efficient and minimally invasive vectors are generally considered to be the ideal drug delivery system (DDS). However, against cancer, DDS equipped with antitumor activities may be a therapeutic choice. By combining therapeutic molecules with DDS having antitumor activities, enhancement of the multiple therapeutic pathways may be achieved.

Photothermal release of single-stranded DNA from the surface of gold nanoparticles through controlled denaturating and Au-S bond breaking

Photothermal release of DNA from gold nanoparticles either by thermolysis of the Au-S bonds used to anchor the oligonucleotides to the nanoparticle or by thermal denaturation has great therapeutic potential, however, both processes have limitations (a decreased particle stability for the former process and a prohibitively slow rate of release for the latter). Here we show that these two mechanisms are not mutually exclusive and can be controlled by adjusting laser power and ionic strength. We show this using two different double-stranded (ds)DNA-nanoparticle conjugates, in which either the anchored sense strand or the complementary antisense strand was labeled with a fluorescent marker. The amounts of release due to the two mechanisms were evaluated using fluorescence spectroscopy and capillary electrophoresis, which showed that irradiation of the decorated particles in 200 mM NaOAc containing 10 mM Mg(OAc)(2) with a pulsed 532 nm laser operating at 100 mW favors denaturation over Au-S cleavage to an extent of more than six-to-one. Due to the use of a pulsed laser, the process occurs on the order of minutes rather than hours, which is typical for continuous wave lasers. These findings encourage continued research toward developing photothermal gene therapeutics.

Central nervous system delivery of large molecules: challenges and new frontiers for intrathecally administered therapeutics

IMPORTANCE OF THE FIELD

Therapeutic proteins and DNA constructs offer promise for the treatment of central nervous system disorders, yet significant biological barriers limit the ability of these molecules to reach the central nervous system from the bloodstream. Direct administrations to the cerebrospinal fluid (intrathecal administration) comprise an emerging field to facilitate the efficient delivery of these biological macromolecules to central nervous system tissues.

AREAS COVERED IN THIS REVIEW

Previous reports from 1990 to the present time describing the interactions and turnover of the cerebrospinal fluid within the intrathecal space, characterizations of the effects that therapeutic proteins and DNA have shown after intrathecal delivery through a lumbar route, and reports of emerging technologies to address the limitations of intrathecally administered macromolecules are reviewed.

WHAT THE READER WILL GAIN

This review provides an overview of the limitations that must be overcome for intrathecally administered biological macromolecules and the recent advances and promising approaches for surmounting these limitations.

TAKE HOME MESSAGE

Emerging approaches that stabilize and sustain the delivery of intrathecally administered biological macromolecules may enhance substantially the clinical relevance of promising therapeutic proteins and DNA constructs for the treatment of various central nervous system disorders.

Trafficking microenvironmental pHs of polycationic gene vectors in drug-sensitive and multidrug-resistant MCF7 breast cancer cells

While multidrug resistance (MDR) has been a significant issue in cancer chemotherapy, delivery resistance to various anti-cancer biotherapeutics, including genes, has not been widely recognized as a property of MDR. This study aims to provide a better understanding of the transfection characteristics of drug-sensitive and drug-resistant cells by tracing microenvironmental pHs of two representative polymer vectors: poly(L-lysine) and polyethyleneimine. Drug-sensitive breast MCF7 cells had four- to seven-times higher polymeric transfection efficiencies than their counterpart drug-resistant MCF7/ADR-RES cells. Polyplexes in MCF7/ADR-RES cells after endocytosis were exposed to a more acidic microenvironment than those in MCF7 cells; the MDR cells show faster acidification rates in endosomes/lysosomes than the drug-sensitive cells after endocytosis (in the case of PLL/pDNA complexes, approximately pH 5.1 for MCF7/ADR-RES cells vs. approximately pH 6.8 for MCF7 cells at 0.5 h post-transfection). More polyplexes were identified trapped in acidic subcellular compartments of MCF7/ADR-RES cells than in MCF7 cells, suggesting that they lack endosomal escaping activity. These findings demonstrate that the design of polymer-based gene delivery therapeutics should take into account the pH of subcellular compartments.

Polymer-enhanced adenoviral transduction of CAR-negative bladder cancer cells

The application of adenoviral gene therapy for cancer is limited by immune clearance of the virus as well as poor transduction efficiency, since the protein used for viral entry (CAR) serves physiological functions in adhesion and is frequently decreased among cancer cells. Cationic polymers have been used to enhance adenoviral gene delivery, but novel polymers with low toxicity are needed to realize this approach. We recently identified polymers that were characterized by high transfection efficiency of plasmid DNA and a low toxicity profile. In this study we evaluated the novel cationic polymer EGDE-3,3' for its potential to increase adenoviral transduction of the CAR-negative bladder cancer cell line TCCSUP. The amount of adenovirus required to transduce 50-60% of the cells was reduced 100-fold when Ad.GFP was preincubated with the EGDE-3,3' polymer. Polyethyleneimine (pEI), a positively charged polymer currently used as a standard for enhancing adenoviral transduction, also increased infectivity, but transgene expression was consistently higher with EGDE-3,3'. In addition, EGDE-3,3'-supplemented transduction of an adenovirus expressing an apoptosis inducing transgene, Ad.GFP-TRAIL, significantly enhanced the amount of cell death. Thus, our results indicate that novel biocompatible polymers may be useful in improving the delivery of adenoviral gene therapy.

Biotinylated disulfide containing PEI/avidin bioconjugate shows specific enhanced transfection efficiency in HepG2 cells

Targeting of non-viral gene vectors to liver cells could offer the opportunity to cure liver diseases. In this paper, disulfide-containing polyethylenimine (PEI-SS) was synthesized from low molecular weight branched PEI and cystamine bisacrylamide (CBA), and then grafted with biotin. The obtained biotinylated PEI-SS was bioconjugated with avidin via the biotin-avidin interaction to form a novel gene vector, biotinylated PEI-SS/avidin bioconjugate (ABP-SS). Characteristics of ABP-SS and its pDNA complexes were evaluated in terms of acid-base titration, agarose gel electrophoresis, SEM morphology observation, particle size and zeta-potential measurements, and PEI-SS was used as the control. The acid-base titration results showed that ABP-SS exhibited comparable buffer capability to 25 kDa PEI. The results of gel electrophoresis indicated that ABP-SS was able to condense pDNA efficiently at an N/P ratio of 6 and could be degraded by reducing agent DTT. The ABP-SS/pDNA complexes had a mean particle size of 226 +/- 40 nm and surface charges of 25 mV. The SEM images showed that the complexes had compact structures with spherical or quadrate shapes. In vitro cell viability and transfection of ABP-SS and PEI-SS were compared in HepG2, 293T and H446 cells. Among the three different cell lines, compared with PEI-SS, ABP-SS exhibited much lower cytotoxicity and higher transfection efficacy in HepG2 cells due to the biocompatibility of avidin and the specific interactions between avidin and HepG2 cells. Molecular probes were used to reveal the cellular uptake of complexes, and the results demonstrated that ABP-SS contributes to more cellular uptake of complexes in HepG2 cells, which was consistent with the transfection results.

New strategies for cancer gene therapy: progress and opportunities

1. To date, cancer persists as one of the most devastating diseases worldwide. Problems such as metastasis and tumour resistance to chemotherapy and radiotherapy have seriously limited the therapeutic effects of existing clinical treatments. 2. To address these problems, cancer gene therapy has been developing over the past two decades, specifically designed to deliver therapeutic genes to treat cancers using vector systems. So far, a number of genes and delivery vehicles have been evaluated and significant progress has been made with several gene therapy modalities in clinical trials. However, the lack of an ideal gene delivery system remains a major obstacle for the successful translation of regimen to the clinic. 3. Recent understanding of hypoxic and necrotic regions within solid tumours and rapid development of recombinant DNA technology have reignited the idea of using anaerobic bacteria as novel gene delivery systems. These bacterial vectors have unique advantages over other delivery systems and are likely to become the vector of choice for cancer gene therapy in the near future. 4. Meanwhile, complicated tumour pathophysiology and associated metastasis make it hard to rely on a single therapeutic modality for complete tumour eradication. Therefore, the combination of cancer gene therapy with other conventional treatments has become paramount. 5. The present review introduces important cancer gene therapy strategies and major vector systems that have been studied so far with an emphasis on bacteria-mediated cancer gene therapy. In addition, exemplary combined therapies are briefly reviewed.

Protein kinase Calpha-responsive polymeric carrier: its application for gene delivery into human cancers

For cancer-targeting gene delivery, we applied a protein kinase C (PKC)alpha-responsive polymeric carrier to human cancers (U-87 MG [human glioblastoma-astrocytoma, epithelial-like cell line] and A549 [human lung adenocarcinoma epithelial cell line]). Two polymers, one a PKCalpha-responsive polymer (PPC[S]) containing the phosphorylation site serine, and the other a negative control polymer (PPC[A]), in which the serine was substituted with alanine, were synthesized. No cytotoxicity of the polymer was identified. When the complexes were transfected into cancer cells or tissues in which PKCalpha was hyper-activated, the luciferase expression from the PPC(S)/plasmid (pDNA) complex was higher than that from the PPC(A)/pDNA complex. These results show that the phosphorylation of complex by PKCalpha in cancer cells leads to high gene expression and that our system can be used as a human cancer cell-targeting gene delivery system.

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.

In-vivo gene transfer induces transgene expression in cells and secretions of the mouse cauda epididymis

Mouse cauda epididymis were in-vivo transfected using the lipid FuGENE 6 as gene vector. Two gene constructions were employed: the p-GeneGRIP which codifies for the Green Fluorescent Protein (GFP) and the pSEAP-control that expresses an alkaline phosphatase as a secretion. Transfection was detected by fluorescence and appeared in the nucleus and cytoplasm of epithelial cells. Transfection was observed in 39.70% of cells after 2 days and in 31.77% after 7 days, and then diminished progressively. Moreover, the presence of the transgene in the DNA isolated from treated epididymides was observed by polymerase chain reaction. GFP gene expression appeared in large areas of the cauda epididymis and it was observed exclusively in the cytoplasm of epithelial cells. GFP gene expression occurred during 2 weeks after gene injection and occupied 32.24, 29.98 and 22.37% of the area of the tubules when analyzed 2, 7 and 15 days after gene injection. The cauda was also analyzed in toto and showed similar results. The use of the pSEAP-control gene showed that cauda epididymis secretions can also be modified by the transfection procedure. A significant increase of alkaline phosphatase activity appeared in the epididymal fluids 7 days after gene injection. These results indicate that transfection procedures could be an important tool in the future to study epididymal physiology or to change the fertilizing ability of spermatozoa.