Gene delivery by an epidermal growth factor/DNA polyplex to small cell lung cancer cell lines expressing low levels of epidermal growth factor receptor

Critical roles for EGFR and EGFR-HER2 clusters in EGF binding of SW620 human carcinoma cells

Epidermal growth factor (EGF) signalling regulates normal epithelial and other cell growth, with EGF receptor (EGFR) overexpression reported in many cancers. However, the role of EGFR clusters in cancer and their dependence on EGF binding is unclear. We present novel single-molecule total internal reflection fluorescence microscopy of (i) EGF and EGFR in living cancer cells, (ii) the action of anti-cancer drugs that separately target EGFR and human EGFR2 (HER2) on these cells and (iii) EGFR–HER2 interactions. We selected human epithelial SW620 carcinoma cells for their low level of native EGFR expression, for stable transfection with fluorescent protein labelled EGFR, and imaged these using single-molecule localization microscopy to quantify receptor architectures and dynamics upon EGF binding. Prior to EGF binding, we observe pre-formed EGFR clusters. Unexpectedly, clusters likely contain both EGFR and HER2, consistent with co-diffusion of EGFR and HER2 observed in a different model CHO-K1 cell line, whose stoichiometry increases following EGF binding. We observe a mean EGFR : EGF stoichiometry of approximately 4 : 1 for plasma membrane-colocalized EGFR–EGF that we can explain using novel time-dependent kinetics modelling, indicating preferential ligand binding to monomers. Our results may inform future cancer drug developments.

Advances in Targeted Gene Delivery

Gene therapy has the potential to treat both acquired and inherited genetic diseases. Generally, two types of gene delivery vectors are used - viral vectors and non-viral vectors. Non-viral gene delivery systems have attracted significant interest (e.g. 115 gene therapies approved for clinical trials in 2018; clinicaltrials.gov) due to their lower toxicity, lack of immunogenicity and ease of production compared to viral vectors. To achieve the goal of maximal therapeutic efficacy with minimal adverse effects, the cell-specific targeting of non-viral gene delivery systems has attracted research interest. Targeting through cell surface receptors; the enhanced permeability and retention effect, or pH differences are potential means to target genes to specific organs, tissues, or cells. As for targeting moieties, receptorspecific ligand peptides, antibodies, aptamers and affibodies have been incorporated into synthetic nonviral gene delivery vectors to fulfill the requirement of active targeting. This review provides an overview of different potential targets and targeting moieties to target specific gene delivery systems.

DDMC-p53 gene therapy with or without cisplatin and microwave ablation

Lung cancer remains the leading cause of death in cancer patients. Severe treatment side effects and late stage of disease at diagnosis continue to be an issue. We investigated whether local treatment using 2-diethylaminoethyl-dextran methyl methacrylate copolymer with p53 (DDMC-p53) with or without cisplatin and/or microwave ablation enhances disease control in BALBC mice. We used a Lewis lung carcinoma cell line to inoculate 140 BALBC mice, which were divided into the following seven groups; control, cisplatin, microwave ablation, DDMC-p53, DDMC-p53 plus cisplatin, DDMC-p53 plus microwave, and DDMC-p53 plus cisplatin plus microwave. Microwave ablation energy was administered at 20 W for 10 minutes. Cisplatin was administered as 1 mL/mg and the DDMC-p53 complex delivered was 0.5 mL. Increased toxicity was observed in the group receiving DDMC-p53 plus cisplatin plus microwave followed by the group receiving DDMC-p53 plus cisplatin. Infection after repeated treatment administration was a major issue. We conclude that a combination of gene therapy using DDMC-p53 with or without cisplatin and microwave is an alternative method for local disease control. However, more experiments are required in a larger model to identify the appropriate dosage profile.

Intratumoral gene therapy versus intravenous gene therapy for distant metastasis control with 2-diethylaminoethyl-dextran methyl methacrylate copolymer non-viral vector-p53

Lung cancer still remains to be challenged by novel treatment modalities. Novel locally targeted routes of administration are a methodology to enhance treatment and reduce side effects. Intratumoral gene therapy is a method for local treatment and could be used either in early-stage lung cancer before surgery or at advanced stages as palliative care. Novel non-viral vectors are also in demand for efficient gene transfection to target local cancer tissue and at the same time protect the normal tissue. In the current study, C57BL/6 mice were divided into three groups: (a) control, (b) intravenous and (c) intatumoral gene therapy. The novel 2-Diethylaminoethyl-Dextran Methyl Methacrylate Copolymer Non-Viral Vector (Ryujyu Science Corporation) was conjugated with plasmid pSicop53 from the company Addgene for the first time. The aim of the study was to evaluate the safety and efficacy of targeted gene therapy in a Lewis lung cancer model. Indeed, although the pharmacokinetics of the different administration modalities differs, the intratumoral administration presented increased survival and decreased distant metastasis. Intratumoral gene therapy could be considered as an efficient local therapy for lung cancer.

Inhaled gene therapy in lung cancer: proof-of-concept for nano-oncology and nanobiotechnology in the management of lung cancer

Lung cancer still remains one of the leading causes of death among cancer patients. Although novel targeted therapies have been established in everyday treatment practice, and conventional platinum-based doublets have demonstrated effective results regarding overall and progression-free survival, we have still failed to achieve long-term survival. Therefore, several strategies of applying locoregional therapy are under investigation. Aerosol chemotherapy is already under investigation and, taking this a step further, aerosol gene therapies with multiple delivery systems are being developed. Several efforts have demonstrated its efficiency and effectiveness, but there are still multiple factors that have to be considered and combined to achieve an overall more effective multifunctional treatment. In the current review, we present data regarding aerosol delivery systems, transporters, carriers, vectors, genes, toxicity, efficiency, specificity, lung microenvironment and delivery gene therapy systems. Finally, we present current studies and future perspectives.

A peptide-mediated targeting gene delivery system for malignant glioma cells

Glioblastoma multiforme (GBM) is the most common and malignant glioma. Although there has been considerable progress in treatment strategies, the prognosis of many patients with GBM remains poor. In this work, polyethylenimine (PEI) and the VTWTPQAWFQWV (VTW) peptide were modified and synthesized into GBM-targeting nanoparticles. The transfection efficiency of U-87 (human glioblastoma) cells was evaluated using fluorescence microscopy and flow cytometry. Cell internalization was investigated to verify the nanoparticle delivery into the cytoplasm. Results showed that the methods of polymer conjugation and the amount of VTW peptide were important factors to polymer synthesis and transfection. The PEI-VTW₂₀ nanoparticles increased the transfection efficiency significantly. This report describes the use of VTW peptide-based PEI nanoparticles for intracellular gene delivery in a GBM cell-specific manner.

2-diethylaminoethyl-dextran methyl methacrylate copolymer nonviral vector: still a long way toward the safety of aerosol gene therapy

Revealing the lung tumor genome has directed the current treatment strategies toward targeted therapy. First line treatments targeting the genome of lung tumor cells have been approved and are on the market. However, they are limited by the small number of patients with the current investigated genetic mutations. Novel treatment administration modalities have been also investigated in an effort to increase the local drug deposition and disease control. In the current study, we investigated the safety of the new nonviral vector 2-diethylaminoethyl-dextran methyl methacrylate copolymer (DDMC; Ryujyu Science), which belongs to the 2-diethylaminoethyl-dextran family by aerosol administration. Thirty male BALBC mice, 2 month old, were included and divided into three groups. However, pathological findings indicated severe emphysema within three aerosol sessions. In addition, the CytoViva technique was applied for the first time to display the nonviral particles within the pulmonary tissue and emphysema lesions, and a spectral library of the nonviral vector was also established. Although our results in BALBC mice prevented us from further investigation of the DDMC nonviral vector as a vehicle for gene therapy, further investigation in animals with larger airways is warranted to properly evaluate the safety of the vector.

Vectors for inhaled gene therapy in lung cancer. Application for nano oncology and safety of bio nanotechnology

Novel aerosol therapeutic modalities have been investigated for lung cancer. Inhaled gene therapy has presented safety and effectiveness previously in cystic fibrosis. However, safety concerns have been raised regarding the safety of non-viral vectors for inhaled gene therapy in lung cancer, and therefore small steps have been made towards this multifunctional treatment modality. During the last decade, numerous new nanocomplexes have been created and investigated as a safe gene delivery nano-vehicle. These formulations are multifunctional; they can be used as either local therapy or carrier for an effective inhaled gene therapy for lung cancer. Herein, we present current and future perspectives of nanocomplexes for inhaled gene therapy treatment in lung cancer.

A novel EGFR-targeted gene delivery system based on complexes self-assembled by EGF, DNA, and activated PAMAM dendrimers

Epidermal growth factor receptor (EGFR)-targeted gene delivery is a promising approach in gene therapy against EGFR-positive cancer. In addition, macromolecules, such as polyamidoamine (PAMAM) dendrimers, are potential nonviral gene carriers in this therapy because of their biocompatibility and modifiable features. To achieve the goal of selectively enhancing the transfection efficiency in EGFR-positive cancer cells, the researchers developed chemical approaches of EGF-dendrimer conjugate, which were effective but complicated. Studies on liposomes reveal that self-assembly is another effective but simpler approach in EGF modification. Moreover, properly activated PAMAM dendrimers exhibit higher transfection efficiency, but little research has been done on its ligand-modification. In this study, we developed and characterized a novel gene-delivery system based on activated EGF-dendriplexes, which is formed via self-assembly by EGF and complexes prepared by activated PAMAM dendrimer and plasmid DNA. Such complexes exhibit desired features compared to nonmodified or non-activated dendriplexes in vitro, including selective enhancement of transfection efficiency in EGFR-positive cells, decreased cytotoxicity, and low agonist effect. In vivo experimentation shows their EGFR-positive tumor targeted biodistribution and increased transfection efficiency at EGFR-positive tumors. Our results demonstrated that activated EGF-dendriplexes are safe and effective carriers for delivering gene drugs to EGFR-positive cells, which makes these complexes a promising targeted nonviral gene-delivery system for auxiliary cancer therapy.

Single-particle tracking as a quantitative microscopy-based approach to unravel cell entry mechanisms of viruses and pharmaceutical nanoparticles

Highly sensitive fluorescence microscopy techniques allow single nanoparticles to be tracked during their uptake into living cells with high temporal and spatial resolution. From analysis of the trajectories, random motion can be discriminated from active transport and the average transport velocity and/or diffusion coefficient determined. Such an analysis provides important information regarding the uptake pathway and location of viruses and nanoparticles. In this review, we give an introduction into single-particle tracking (SPT) and determination of the mean-squared displacement. We also give an overview of recent advances in SPT. These include millisecond alternating-laser excitation for removal of spectral crosstalk, alternating wide-field (WF), and total internal reflection fluorescence (TIRF) microscopy for sensitive experiments at the plasma membrane and three-dimensional tracking strategies. Throughout the review, we highlight recent advances regarding the entry (and egress) of natural and artificial viruses obtained via SPT.

The mechanism of selective transfection mediated by pentablock copolymers; part I: investigation of cellular uptake

Poly(diethylaminoethylmethacrylate) (PDEAEM) and Pluronic F127 based pentablock copolymer vectors with the ability to transfect cancer cells selectively over normal cells in in vitro cultures were developed, as described in a previous report. Understanding the mechanism of this selectivity will enable better polymeric vectors to be designed, with inherent selectivity for specific cell types based on intracellular differences and not on the use of targeting ligands, which have shown variable success, depending on the system. It is assumed that the selectivity was due to different intracellular barriers to transfection in the different cell types. Part I focuses on investigating whether cellular entry is one of the barriers to transfection, through conjugation of epidermal growth factor (EGF) to the pentablock copolymer vector. Results indicate that EGF conjugation increased transfection efficiency the most when conjugated to the outer surface of polyplexes, with minimal disruption to DNA packaging and maximal accessibility to receptors. The overall resulting enhancement in transfection, however, was a moderate three- to five-fold increase compared with the condition with no EGF involved, implying that the addition of EGF fails to overcome the intracellular barrier to transfection, which probably involves some step other than cellular uptake in pentablock copolymer system. Therefore, the differences observed in the selectivity of transfection between cancer and normal cell lines is probably not controlled by differences in cellular entry, and the intracellular barriers to transfection in this system are likely to be endosomal escape or nuclear entry, as investigated in Part II, the companion paper to this work.

Efficient gene delivery by EGF-lipoplexes in vitro and in vivo

Aims: In this work, we have evaluated the ability of targeted lipoplexes to enhance transgene expression in EGF receptor (EGFR) overexpressing tumor cells by using lipoplexes. Materials & methods: We prepared DOTAP/cholesterol liposomes modified with EGF at 0.5/1, 1/1, 2/1 and 5/1 lipid/DNA (+/-) charge ratio by sequentially mixing the liposomes with the ligand and adding the reporter or the therapeutic plasmid gene, pCMVLuc (pVR1216) or pCMVIL12, respectively. HepG2, DHDK12proB and SW620 cells were used for in vitro experiments, which were performed in the presence of 60% serum. Results: The characterization of EGF-lipoplexes indicated a size close to 300 nm and a variable net surface charge as a function of the amount of EGF associated to the cationic liposomes. EGF-lipoplexes, which showed an increased transfection activity, were positively charged, noncytotoxic and highly effective in protecting DNA from DNase I attack. Transfection activity in vitro resulted in an enhancement in the luciferase and IL-12 expression by EGF-lipoplexes compared with those without ligand (plain-lipoplexes) and to naked DNA. The results observed in SW620 cells, which are deficient in EGFR, confirmed that DNA uptake was predominantly via EGFR-mediated endocytosis. In vivo transfection activity was confirmed by luciferase imaging in living mice. Bioluminiscence could be detected mainly in the lung with a maximum signal 24 h after application. The resulting EGF-lipoplexes significantly increased the level of gene expression in mice compared with control or naked DNA. Conclusion: These findings indicate that these nanovectors may be an adequate alternative to viral vectors for gene therapy.

Visualizing uptake and intracellular trafficking of gene carriers by single-particle tracking

Single-particle microscopy und live-cell single-particle tracking are powerful tools to follow the cellular internalization pathway of individual nanoparticles such as viruses and gene carriers and investigate their interaction with living cells. Those single-cell and single-particle methods can elucidate the "black box" between application of the gene carrier to the cell and the final gene expression and allow the essential bottlenecks to be identified in great detail on the cellular level. In this review we will give a short introduction into single-particle tracking microscopy and present an overview of the mechanisms of DNA delivery from attachment to the cell membrane over internalization towards nuclear entry unraveled by single-particle methods.

Solid lipid nanoparticles can effectively bind DNA, streptavidin and biotinylated ligands

Cationic solid lipid nanoparticles (SLN) have recently been suggested for non-viral gene delivery, as these particles consist of well tolerated substances, can bind DNA directly via electrostatic interactions and mediate gene transfer in vitro. We here report the development of SLN complexes, which can be targeted to specific surface receptors. A formulation of SLN was prepared by the microemulsion technique comprising of stearylamine and the matrix lipid Compritol ATO 888 with a size of approximately 100 nm and a zeta-potential of +15. These SLN are able to condense DNA in complexes, which are very stable under physiological conditions, and they display low cytotoxicity in cell culture. In addition to binding of DNA, the SLN can simultaneously bind substantial amounts of streptavidin directly via electrostatic interactions. The SLN:DNA: streptavidin complexes are stable and are capable of binding biotinylated ligands, which can interact with surface receptors. This method allows for development of a fast and simple method of preparing a targeted non-viral gene therapy vector.

Cryoconserved shielded and EGF receptor targeted DNA polyplexes: cellular mechanisms

Recently, cryoconservable polyethylene glycol (PEG)-shielded and epidermal growth factor receptor (EGFR)-targeted polyplexes (EGF+ polyplexes) were engineered in our laboratory for tumor-directed transfer and expression of DNA. Here, we further analyzed specificity and kinetics of EGFR-mediated cellular uptake of these polyplexes. Similar to our previous results, EGF+ polyplexes significantly enhanced the transfection efficiency as compared to polyplexes without EGF (EGF- polyplexes) in HUH-7 hepatoma cells and Renca-EGFR renal carcinoma cells. EGF+ polyplexes rapidly associated with the cells within 30 min of exposure, and binding of EGF+ polyplexes to the cells after 4 h was significantly higher than that of EGF- polyplexes. In the presence of free EGF, both cell association and transfection efficiency of EGF+ polyplexes were markedly reduced indicating that these effects were primarily mediated via ligand receptor interaction. Fluorescence microscopy revealed that the cell-associated EGF+ polyplexes aggregated to micrometer sized clusters, resembling typical clustering of receptors upon ligand binding. In conclusion, EGFR-targeting enhances transfection efficiency due to accelerated and increased cell association followed by aggregation of the bound EGF+ polyplexes.

Carrier-based strategies for targeting protein and peptide drugs to the lungs

With greater interest in delivery of protein and peptide-based drugs to the lungs for topical and systemic activity, a range of new devices and formulations are being investigated. While a great deal of recent research has focused on the development of novel devices, attention must now be paid to the formulation of these macromolecular drugs. The emphasis in this review will be on targeting of protein/peptide drugs by inhalation using carriers and ligands.

Photochemically enhanced gene delivery of EGF receptor-targeted DNA polyplexes

Epidermal growth factor receptor (EGFR) targeted DNA polyplexes, containing polyethylenimine (PEI) conjugated with EGF protein as cell-binding ligand for endocytosis and polyethylene glycol (PEG) for masking the polyplex surface charge, mediated a 3- to 30-fold higher luciferase gene expression in HUH7, HepG2 and A431 cell transfections than analogous untargeted PEG-PEI polyplexes. Transfection levels can be further enhanced by treatment of cells with amphiphilic photosensitizers followed by illumination. In this process photosensitizers localized in membranes of endocytic vesicles are activated by light, resulting in the destruction of endocytic membrane structures and releasing co-endocytosed polyplexes into the cell cytosol. Photochemical enhanced gene expression was observed in all cell lines, with the magnitude of enhancement depending on the particular PEI polyplex formulation and cell line, ranging between 2- and 600-fold. Importantly, improved gene transfer retained EGF receptor specificity, as demonstrated by comparison with ligand-free polyplexes and by receptor antibody or ligand competition experiments. These results suggest that this combined procedure enables a dual mode of targeting polyplexes: biological targeting via EGFR interaction, combined with physical targeting with light to direct a photochemical delivery of therapeutic genes to a desired location.

Enhanced antitumor effect of EGF R-targeted p21WAF-1 and GM-CSF gene transfer in the established murine hepatoma by peritumoral injection

One of the major obstacles in current cancer gene therapy is the lack of a gene delivery system with high efficiency and targetability. In this paper, a nonviral gene delivery system GE7, which was designed to target EGF receptor (EGF R) overexpressed on the surface of cancer cel Is through an EGF R-binding oligopeptide (GE7), was used for in vivo gene therapy in a murine subcutaneous hepatoma model. It was demonstrated that the GE7 system could target the reporter gene beta-gal to EGF R-expressing hepatoma cells with high efficiency after in vitro transfection and in vivo peritumoral injection. To improve the therapeutic effect elicited by single gene transfer, human cyclin-dependent kinase inhibitor gene p21WAF-1 and murine cytokine gene GM-CSFwere used simultaneously in peritumoral injection of the GE7/DNA polyplex. The results showed that combined gene transfer of p21WAF-1 and GM-CSF could inhibit the growth of pre-established tumor more effectively and prolong the survival time of hepatoma-bearing mice more significantly than the transfer of a single gene. Apoptosis in the tumor tissues were found when injected with the p21WAF1-DNA polyplex. Prominent inflammatory infiltration was observed in the tumor tissue transfected with the GM-CSF DNA polyplex. Our data demonstrate that the GE7 system-mediated, EGF R-targeted cotransfer of p21WAF-1 and GM-CSF genes exhibit more potent antitumor effect by inducing tumor cell apoptosis and inflammatory responses.