Therapeutic properties of a vector carrying the HSV thymidine kinase and GM-CSF genes and delivered as a complex with a cationic copolymer

Designing cytochrome P450 enzymes for use in cancer gene therapy

Cancer is a significant global socioeconomic burden, as millions of new cases and deaths occur annually. In 2020, almost 10 million cancer deaths were recorded worldwide. Advancements in cancer gene therapy have revolutionized the landscape of cancer treatment. An approach with promising potential for cancer gene therapy is introducing genes to cancer cells that encode for chemotherapy prodrug metabolizing enzymes, such as Cytochrome P450 (CYP) enzymes, which can contribute to the effective elimination of cancer cells. This can be achieved through gene-directed enzyme prodrug therapy (GDEPT). CYP enzymes can be genetically engineered to improve anticancer prodrug conversion to its active metabolites and to minimize chemotherapy side effects by reducing the prodrug dosage. Rational design, directed evolution, and phylogenetic methods are some approaches to developing tailored CYP enzymes for cancer therapy. Here, we provide a compilation of genetic modifications performed on CYP enzymes aiming to build highly efficient therapeutic genes capable of bio-activating different chemotherapeutic prodrugs. Additionally, this review summarizes promising preclinical and clinical trials highlighting engineered CYP enzymes' potential in GDEPT. Finally, the challenges, limitations, and future directions of using CYP enzymes for GDEPT in cancer gene therapy are discussed.

Suicide gene delivery by morphology-adaptable enantiomeric peptide assemblies for combined ovarian cancer therapy

Suicide gene therapy is a promising therapeutic model for ovarian cancer (OC), while suffering from poor gene delivery and limited therapeutic efficacy. To address this concern, here we reported the GSH-responsive morphology-transformable enantiomeric peptide assemblies as delivering vehicles for suicide genes and co-delivery of paclitaxel (PTX). Connecting a lipid-like amphiphile and a hydrophilic arginine segment through disulfide bonds led to the enantiomeric peptides. The enantiomeric peptide assemblies are able to simultaneously uptake plasmid DNA (pDNA) and PTX based on electrostatic and hydrophobic interactions. The resulting co-assemblies underwent GSH-responsive disulfide cleavage and thereby promoting their assembly from nanoparticles to nanofibers, leading to the co-release of pDNA and PTX. Cellular and animal studies confirmed the co-delivery of pDNA and PTX into OC cells and the cell apoptosis by the enantiomeric peptides. In addition, in vitro and in vivo experiments supported the advanced uptake and cytotoxicity for L-type peptide vehicles by OC cells, and their great potential for OC-imaging, growth-inhibition and apoptosis-induction compared to D-counterpart. Our results demonstrate that the GSH-responsive morphology-transformable chiral peptide assemblies accurately and simultaneously release suicide genes and chemodrugs at tumor sites, thus providing a new strategy for the development of delivering vehicles for suicide gene and establishment of new therapeutic models for ovarian cancer. STATEMENT OF SIGNIFICANCE: Appropriate delivery carriers are essential for the clinical translation of cancer gene therapy, including the emerging suicide gene therapy. By combining the advantages of morphological transformable vehicles with the chirality peptides towards their bioactivity, we developed the GSH-responsive morphology-transformable enantiomeric peptide assemblies as delivering vehicles for suicide genes and co-delivery of paclitaxel. The GSH-responsive assembly of the enantiomeric peptides allows for precise release of plasmid DNA and paclitaxel in cancer cells, and promotes the formation of nanofibrils that facilitate gene entering nuclei for transfection. The enantiomeric peptide-based vehicles show the chirality-dependent capability for inducing cell apoptosis and inhibiting tumor growth. Our findings demonstrate a new strategy for developing therapeutic models for ovarian cancer.

Prospects for the Use of Metal-Based Nanoparticles as Adjuvants for Local Cancer Immunotherapy

Immunotherapy is among the most effective approaches for treating cancer. One of the key aspects for successful immunotherapy is to achieve a strong and stable antitumor immune response. Modern immune checkpoint therapy demonstrates that cancer can be defeated. However, it also points out the weaknesses of immunotherapy, as not all tumors respond to therapy and the co-administration of different immunomodulators may be severely limited due to their systemic toxicity. Nevertheless, there is an established way through which to increase the immunogenicity of immunotherapy-by the use of adjuvants. These enhance the immune response without inducing such severe adverse effects. One of the most well-known and studied adjuvant strategies to improve immunotherapy efficacy is the use of metal-based compounds, in more modern implementation-metal-based nanoparticles (MNPs), which are exogenous agents that act as danger signals. Adding innate immune activation to the main action of an immunomodulator makes it capable of eliciting a robust anti-cancer immune response. The use of an adjuvant has the peculiarity of a local administration of the drug, which positively affects its safety. In this review, we will consider the use of MNPs as low-toxicity adjuvants for cancer immunotherapy, which could provide an abscopal effect when administered locally.

Looking for Tumor Specific Promoters In Silico

Abstract—

Previously we demonstrated the tumor-specific activity of several human native and chimeric promoters. Here we have analyzed the DNA sequences of experimentally tested tumor-specific promoters for the presence of recognition matrices of transcription factors and for de novo motif discovery. CiiiDER and MEME Suite software tools were used for this purpose. A number of transcription factor matrices have been identified, which are present more often in tumor-specific promoters than in the promoters of housekeeping genes. New promoter–TF regulatory relationships have been predicted by pathway analysis. A motif of 44 bp characteristic of tumor-specific promoters but not of housekeeping gene promoters has been discovered. The search through 29 598 human promoters from the EPDnew promoter database has revealed a series of promoters with this motif, their genes being associated with unfavorable prognoses in cancer. We suppose that some of these promoters may possess a tumor specific activity. In addition, a close similarity in nucleotide motifs between the promoters of the BIRC5 and MCM2 genes has been shown. The results of the study may contribute to understanding the peculiarities of gene transcription in tumors, as well as to searching for native tumor-specific promoters or creating artificial ones for cancer gene therapy, as well as in the development of anticancer vaccines.

Step-by-Step Immune Activation for Suicide Gene Therapy Reinforcement

Gene-directed enzyme prodrug gene therapy (GDEPT) theoretically represents a useful method to carry out chemotherapy for cancer with minimal side effects through the formation of a chemotherapeutic agent inside cancer cells. However, despite great efforts, promising preliminary results, and a long period of time (over 25 years) since the first mention of this method, GDEPT has not yet reached the clinic. There is a growing consensus that optimal cancer therapies should generate robust tumor-specific immune responses. The advent of checkpoint immunotherapy has yielded new highly promising avenues of study in cancer therapy. For such therapy, it seems reasonable to use combinations of different immunomodulators alongside traditional methods, such as chemotherapy and radiotherapy, as well as GDEPT. In this review, we focused on non-viral gene immunotherapy systems combining the intratumoral production of toxins diffused by GDEPT and immunomodulatory molecules. Special attention was paid to the applications and mechanisms of action of the granulocyte-macrophage colony-stimulating factor (GM–CSF), a cytokine that is widely used but shows contradictory effects. Another method to enhance the formation of stable immune responses in a tumor, the use of danger signals, is also discussed. The process of dying from GDEPT cancer cells initiates danger signaling by releasing damage-associated molecular patterns (DAMPs) that exert immature dendritic cells by increasing antigen uptake, maturation, and antigen presentation to cytotoxic T-lymphocytes. We hypothesized that the combined action of this danger signal and GM–CSF issued from the same dying cancer cell within a limited space would focus on a limited pool of immature dendritic cells, thus acting synergistically and enhancing their maturation and cytotoxic T-lymphocyte attraction potential. We also discuss the problem of enhancing the cancer specificity of the combined GDEPT–GM–CSF–danger signal system by means of artificial cancer specific promoters or a modified delivery system.

Possibility for Transcriptional Targeting of Cancer-Associated Fibroblasts-Limitations and Opportunities

Cancer-associated fibroblasts (CAF) are attractive therapeutic targets in the tumor microenvironment. The possibility of using CAFs as a source of therapeutic molecules is a challenging approach in gene therapy. This requires transcriptional targeting of transgene expression by cis-regulatory elements (CRE). Little is known about which CREs can provide selective transgene expression in CAFs. We hypothesized that the promoters of FAP, CXCL12, IGFBP2, CTGF, JAG1, SNAI1, and SPARC genes, the expression of whose is increased in CAFs, could be used for transcriptional targeting. Analysis of the transcription of the corresponding genes revealed that unique transcription in model CAFs was characteristic for the CXCL12 and FAP genes. However, none of the promoters in luciferase reporter constructs show selective activity in these fibroblasts. The CTGF, IGFBP2, JAG1, and SPARC promoters can provide higher transgene expression in fibroblasts than in cancer cells, but the nonspecific viral promoters CMV, SV40, and the recently studied universal PCNA promoter have the same features. The patterns of changes in activity of various promoters relative to each other observed for human cell lines were similar to the patterns of activity for the same promoters both in vivo and in vitro in mouse models. Our results reveal restrictions and features for CAF transcriptional targeting.

Suicide gene therapy-mediated purine nucleoside phosphorylase/fludarabine system for in vitro breast cancer model with emphasis on evaluation of vascular endothelial growth factor promoter efficacy

In this study, a suicide gene therapy approach was optimized by a non-viral polyplex system based on pEGFP-N1 vector harboring purine nucleoside phosphorylase gene conducted by vascular endothelial growth factor promoter for an in vitro breast cancer model (4T1 cell line). The VEGF promoter and purine nucleoside phosphorylase gene were cloned into the vector from the source of 4T1 and E. coli genomic DNA, respectively. A gene construct was developed by replacing VEGF promoter instead of CMV promoter in pEGFP-N1vector. PNP gene was integrated in to the multiple cloning site of the obtained vector. On the other hand, a construct from pEGFP-N1 harboring PNP gene under the control of the original CMV promoter was developed. The transfection method using cationic polymer was optimized based on N/P ratio, cell cytotoxicity, polyplex size, zeta potential and the green fluorescent protein (GFP) expression by fluorescent microscopy and flowcytometry. Also, the effect of hypoxia condition induced by 0.5 mM H₂O₂ on the promoter efficiency was investigated. The results showed that the performed gene delivery system is capable of the gene transfection to more than 30% of the cancer cells with both VEGF-PNP-pEGFP-N1 and PNP-pEGFP-N1 plasmids. The hypoxia condition did not show a significant effect on the VEGF promoter. But, it revealed that bystander effect can improve the efficacy of this system and reduce drug IC50 to 2 and fourfold for plasmids VEGF-PNP-pEGFP-N1 and PNP-pEGFP-N1, respectively. These results showed that the bystander effect could almost compensate the low efficiency of non-viral gene delivery systems. We suggest that the tumor-specific gene expression system mediated by the VEGF promoter can be especially useful in the present model of breast cancer gene therapy.

Inflammatory Cytokines in Cancer: Comprehensive Understanding and Clinical Progress in Gene Therapy

The relationship between chronic inflammation and neoplastic diseases is not fully understood. The inflammatory microenvironment of a tumor is an intricate network that consists of numerous types of cells, cytokines, enzymes and signaling pathways. Recent evidence shows that the crucial components of cancer-related inflammation are involved in a coordinated system to influence the development of cancer, which may shed light on the development of potential anticancer therapies. Since the last century, considerable effort has been devoted to developing gene therapies for life-threatening diseases. When it comes to modulating the inflammatory microenvironment for cancer therapy, inflammatory cytokines are the most efficient targets. In this manuscript, we provide a comprehensive review of the relationship between inflammation and cancer development, especially focusing on inflammatory cytokines. We also summarize the clinical trials for gene therapy targeting inflammatory cytokines for cancer treatment. Future perspectives concerned with new gene-editing technology and novel gene delivery systems are finally provided.

Novel Histone-Based DNA Carrier Targeting Cancer-Associated Fibroblasts

Nuclear proteins, like histone H2A, are promising non-viral carriers for gene delivery since they are biocompatible, biodegradable, bear intrinsic nuclear localization signal, and are easy to modify. The addition of surface-protein-binding ligand to histone H2A may increase its DNA delivery efficiency. Tumor microenvironment (TME) is a promising target for gene therapy since its surface protein repertoire is more stable than that of cancer cells. Cancer-associated fibroblasts (CAFs) are important components of TME, and one of their surface markers is beta-type platelet-derived growth factor receptor (PDGFRβ). In this study, we fused histone H2A with PDGFRβ-binding peptide, YG2, to create a novel non-viral fibroblast-targeting DNA carrier, H2A-YG2. The transfection efficiency of histone complexes with pDNA encoding a bicistronic reporter (enhanced green fluorescent protein, EGFP, and firefly luciferase) in PDGFRβ-positive and PDGFRβ-negative cells was estimated by luciferase assay and flow cytometry. The luciferase activity, percentage of transfected cells, and overall EGFP fluorescence were increased due to histone modification with YG2 only in PDGFRβ-positive cells. We also estimated the internalization efficiency of DNA-carrier complexes using tetramethyl-rhodamine-labeled pDNA. The ligand fusion increased DNA internalization only in the PDGFRβ-positive cells. In conclusion, we demonstrated that the H2A-YG2 carrier targeted gene delivery to PDGFRβ-positive tumor stromal cells.

Production and Application of Multicistronic Constructs for Various Human Disease Therapies

The development of multicistronic vectors has opened up new opportunities to address the fundamental issues of molecular and cellular biology related to the need for the simultaneous delivery and joint expression of several genes. To date, the examples of the successful use of multicistronic vectors have been described for the development of new methods of treatment of various human diseases, including cardiovascular, oncological, metabolic, autoimmune, and neurodegenerative disorders. The safety and effectiveness of the joint delivery of therapeutic genes in multicistronic vectors based on the internal ribosome entry site (IRES) and self-cleaving 2A peptides have been shown in both in vitro and in vivo experiments as well as in clinical trials. Co-expression of several genes in one vector has also been used to create animal models of various inherited diseases which are caused by mutations in several genes. Multicistronic vectors provide expression of all mutant genes, which allows the most complete mimicking disease pathogenesis. This review comprehensively discusses multicistronic vectors based on IRES nucleotide sequence and self-cleaving 2A peptides, including its features and possible application for the treatment and modeling of various human diseases.

The Antitumor Efficacy of a Complex Based on Two-Vector System for Coexpression of the Suicide Gene Fcu1 and Cre Recombinase

In this study, we evaluated the antitumor activity of a gene therapy complex in which the tumor-specific control of the expression of the effector suicide gene FCU1 was performed using a two-vector system based on the site-specific Cre-LoxP recombinase system. The complex of interest showed a high therapeutic potential in a mouse colon adenocarcinoma model.

Fabrication of a nano polymer wrapping Meg3 ShRNA plasmid for the treatment of cerebral infarction

Cerebral infarction is with poorer prognosis and high rates of mortality. After cerebral infarction, the promoting angiogenesis can accelerate the recovery of neurological function. Long non-coding RNA (LncRNA) maternally expressed gene 3 (Meg3) was overexpressed in cerebral infarction area and the knockdown of Meg3 promotes neovascularization and improves nerve function. In this study, we fabricated a nano-polymer wrapped Meg3 short hairpin RNA (ShRNA) plasmid to knockdown Meg3 and conjugated with OX26 antibody (MPO) to realize the brain targeting for the treatment of cerebral infarction. The MPO particle size was 103 ± 11 nm (PDI = 0.27) detected by dynamic light scattering (DLS) and the zeta potential of MPO was -32 mV. MPO achieved brain microvascular endothelial cell (BMEC) targeting and enhanced endothelial cells migration (p < .05), and tube formation (p < .05) in vitro. MPO realized brain tissue target, reduced the volume of cerebral infarction (p < .05) detected by TTC staining, increased capillary density through the HE staining and increased cerebral cortex micro-vessel through immunofluorescence method in vivo. The angiogenesis associated genes Vegfa, and Vegfr2 were upregulated after the treatment of MPO, compared with Meg3 or control plasmid treated group. This study suggested that MPO could achieve brain target and significantly promoted angiogenesis and became a new treatment method for cerebral infarction.

Antitumor efficacy of combined gene and radiotherapy in animals

Antitumor efficacy of the combined suicide gene therapy and radiotherapy was studied on the model of CT26 murine colon adenocarcinoma. CMV-FCU1-IRES-mGM-CSF-pGL3 construct with PEG-PEI-TAT (FCU1-mGM/5-FC) block copolymer as a vector was used for intratumoral administration. Tumors were irradiated with a single 5 Gy dose. The efficacy was evaluated according to the grade of tumor growth inhibition (T/C) and lifespan of the animals. Pronounced antitumor activity of the combined use of FCU1-mGM/5-FC system with radiotherapy on the background of prolonged lifespan and the synergism of the applied methods was revealed.

Nanoparticle-mediated delivery of suicide genes in cancer therapy

Conventional chemotherapeutics have been employed in cancer treatment for decades due to their efficacy in killing the malignant cells, but the other side of the coin showed off-target effects, onset of drug resistance and recurrences. To overcome these limitations, different approaches have been investigated and suicide gene therapy has emerged as a promising alternative. This approach consists in the introduction of genetic materials into cancerous cells or the surrounding tissue to cause cell death or retard the growth of the tumor mass. Despite promising results obtained both in vitro and in vivo, this innovative approach has been limited, for long time, to the treatment of localized tumors, due to the suboptimal efficiency in introducing suicide genes into cancer cells. Nanoparticles represent a valuable non-viral delivery system to protect drugs in the bloodstream, to improve biodistribution, and to limit side effects by achieving target selectivity through surface ligands. In this scenario, the real potential of suicide genes can be translated into clinically viable treatments for patients. In the present review, we summarize the recent advances of inorganic nanoparticles as non-viral vectors in terms of therapeutic efficacy, targeting capacity and safety issues. We describe the main suicide genes currently used in therapy, with particular emphasis on toxin-encoding genes of bacterial and plant origin. In addition, we discuss the relevance of molecular targeting and tumor-restricted expression to improve treatment specificity to cancer tissue. Finally, we analyze the main clinical applications, limitations and future perspectives of suicide gene therapy.

Polymer-Based Prodrugs: Improving Tumor Targeting and the Solubility of Small Molecule Drugs in Cancer Therapy

The majority of anticancer drugs have poor aqueous solubility, produce adverse effects in healthy tissue, and thus impose major limitations on both clinical efficacy and therapeutic safety of cancer chemotherapy. To help circumvent problems associated with solubility, most cancer drugs are now formulated with co-solubilizers. However, these agents often also introduce severe side effects, thereby restricting effective treatment and patient quality of life. A promising approach to addressing problems in anticancer drug solubility and selectivity is their conjugation with polymeric carriers to form polymer-based prodrugs. These polymer-based prodrugs are macromolecular carriers, designed to increase the aqueous solubility of antitumor drugs, can enhance bioavailability. Additionally, polymer-based prodrugs approach exploits unique features of tumor physiology to passively facilitate intratumoral accumulation, and so improve chemodrug pharmacokinetics and pharmacological properties. This review introduces basic concepts of polymer-based prodrugs, provides an overview of currently emerging synthetic, natural, and genetically engineered polymers that now deliver anticancer drugs in preclinical or clinical trials, and highlights their major anticipated applications in anticancer therapies.

Cancer Stem Cells: Plasticity Works against Therapy

Great successes in identification and deciphering of mechanisms of the adult stem cells regulation have given rise to the idea that stem cells can also function in tumors as central elements of their development, starting from the initial stage and continuing until metastasis. Such cells were called cancer stem cells (CSCs). Over the course of intense discussion, the CSCs hypothesis gradually began to be perceived as an obvious fact. Recently, the existence of CSCs has been indeed confirmed in a number of works. However, when are CSCs universal prerequisites of tumors and to what extent their role is essential for tumor evolution remains an issue far from resolved. Likewise, the problem of potential use of CSCs as therapeutic targets remains unsolved. The present review attempts to analyze the issue of cancer stem cells and the potential of targeting them in tumor therapy.

Bioactive Core-Shell Nanofiber Hybrid Scaffold for Efficient Suicide Gene Transfection and Subsequent Time Resolved Delivery of Prodrug for Anticancer Therapy

Nanofiber scaffold's ability to foster seemingly nonexistent interface with the cells enables them to effectively deliver various bioactive molecules to cells in the vicinity. Among such bioactive molecules, therapeutically active nucleic acid has been the most common candidate. In spite of such magnanimous efforts in this field, it remains a paradox that suicide gene delivery by nanofibers has never been sought for anticancer application. To investigate such a possibility, in the present work, a composite core-shell nanofiberous scaffold has been realized which could efficiently transfect suicide gene into cancer cells and simultaneously deliver prodrug, 5-Fluorocytosine (5-FC) in a controlled and sustained manner. The scaffold's ability to instigate apoptosis by suicide gene therapy in nonsmall lung cancer cells (A549) was ascertained at both phenotypic and genotypic levels. A cascade of events starting from suicide gene polyplex release from nanofibers, transfection, and expression of cytosine deaminase-uracil phosphoribosyltransferase (CD::UPRT) suicide gene by A549; subsequent prodrug release; and its metabolic conversion into toxic intermediates which finally culminates in host cells apoptosis has been monitored in a time-dependent manner. This work opens up new application avenues for nanofiber-based scaffolds which can effectively manage cancer prognosis.