Review article: gene therapy, recent developments and future prospects in gastrointestinal oncology

Stem cells therapy for diabetes: from past to future

Diabetes mellitus is a chronic disease of carbohydrate metabolism characterized by uncontrolled hyperglycemia due to the body's impaired ability to produce or respond to insulin. Oral or injectable exogenous insulin and its analogs cannot mimic endogenous insulin secreted by healthy individuals, and pancreatic and islet transplants face a severe shortage of sources and transplant complications, all of which limit the widespread use of traditional strategies in diabetes treatment. We are now in the era of stem cells and their potential in ameliorating human disease. At the same time, the rapid development of gene editing and cell-encapsulation technologies has added to the wings of stem cell therapy. However, there are still many unanswered questions before stem cell therapy can be applied clinically to patients with diabetes. In this review, we discuss the progress of strategies to obtain insulin-producing cells from different types of stem cells, the application of gene editing in stem cell therapy for diabetes, as well as summarize the current advanced cell encapsulation technologies in diabetes therapy and look forward to the future development of stem cell therapy in diabetes.

Current Advances in the Management of Diabetes Mellitus

Diabetes mellitus (DM) underscores a rising epidemic orchestrating critical socio-economic burden on countries globally. Different treatment options for the management of DM are evolving rapidly because the usual methods of treatment have not completely tackled the primary causes of the disease and are laden with critical adverse effects. Thus, this narrative review explores different treatment regimens in DM management and the associated challenges. A literature search for published articles on recent advances in DM management was completed with search engines including Web of Science, Pubmed/Medline, Scopus, using keywords such as DM, management of DM, and gene therapy. Our findings indicate that substantial progress has been made in DM management with promising results using different treatment regimens, including nanotechnology, gene therapy, stem cell, medical nutrition therapy, and lifestyle modification. However, a lot of challenges have been encountered using these techniques, including their optimization to ensure optimal glycemic, lipid, and blood pressure modulation to minimize complications, improvement of patients' compliance to lifestyle and pharmacologic interventions, safety, ethical issues, as well as an effective delivery system among others. In conclusion, lifestyle management alongside pharmacological approaches and the optimization of these techniques is critical for an effective and safe clinical treatment plan.

Potentialities of Gene Therapy in Pediatric Endocrinology

Gene therapy has become an appealing therapeutic option in many pediatric fields, including endocrinology. Unlike traditional drugs based on molecules that require repeated and frequent burdensome administrations, a single genetic therapeutic intervention may allow durable and curative clinical benefits. Although this highly innovative technology holds a great promise for the treatment of monogenic diseases, its clinical applications in the field of endocrinology have been so far challenging. In this review, we will discuss various ex vivo and in vivo approaches and potential applications of gene addition and gene editing approaches for treating hyperfunctional and hypofunctional endocrine diseases due to intrinsic defects or autoimmune origin. We will focus on the recent advances in gene therapy approaches aimed at treating type 1 diabetes and monogenic forms of endocrinopathies such as growth hormone deficiency, congenital adrenal hyperplasia, diabetes insipidus, IPEX, as well as their trends and future directions.

Room for improvement in the treatment of pancreatic cancer: Novel opportunities from gene targeted therapy

Pancreatic cancer is one of the highest and in fact, unchanged mortality-associated tumor, with an exceptionally low survival rate due to its challenging diagnostic approach. So far, its treatment is based on a combination of approaches (such as surgical resection with or rarely without chemotherapeutic agents), but with finite limits. Thus, looking for additional space to improve pancreatic tumorigenesis therapeutic approach, research has focused on gene therapy with unexpectedly growing horizons not only for the treatment of inoperable pancreatic disease, but also for its early stages. In vivo gene delivery viral vectors, despite few disadvantages (possible immunogenicity, toxicity, mutagenicity, or high cost), could be one of the most efficient cancer gene therapeutic strategies for clinical application due to their superiority compared with other systems (ex vivo delivery strategies). Their dominance consists of simple preparation, easy operation and a wide range of functions. Adenoviruses are one of the most common used vectors, inducing strong immune as well as inflammatory reactions. Oncolytic virotherapy, using the above mentioned in vivo viral vectors, is one of the most promising non-pathogenic, highly-selective cytotoxic anti-cancer therapy using anti-cancer agents with high anti-tumor potency and strong oncolytic effect. There have been a variety of targeted therapeutic and pre-clinical strategies tested for gene therapy in pancreatic cancer such as gene-editing systems (e.g., clustered regularly interspaced palindromic repeats-Cas9), RNA interference technology (e.g., microRNAs, short hairpin RNA or small interfering RNA), adoptive immunotherapy and vaccination (e.g., chimeric antigen receptor T-cell therapy) with encouraging results.

Diagnosis and treatment of type 1 diabetes at the dawn of the personalized medicine era

Type 1 diabetes affects millions of people globally and requires careful management to avoid serious long-term complications, including heart and kidney disease, stroke, and loss of sight. The type 1 diabetes patient cohort is highly heterogeneous, with individuals presenting with disease at different stages and severities, arising from distinct etiologies, and overlaying varied genetic backgrounds. At present, the “one-size-fits-all” treatment for type 1 diabetes is exogenic insulin substitution therapy, but this approach fails to achieve optimal blood glucose control in many individuals. With advances in our understanding of early-stage diabetes development, diabetes stratification, and the role of genetics, type 1 diabetes is a promising candidate for a personalized medicine approach, which aims to apply “the right therapy at the right time, to the right patient”. In the case of type 1 diabetes, great efforts are now being focused on risk stratification for diabetes development to enable pre-clinical detection, and the application of treatments such as gene therapy, to prevent pancreatic destruction in a sub-set of patients. Alongside this, breakthroughs in stem cell therapies hold great promise for the regeneration of pancreatic tissues in some individuals. Here we review the recent initiatives in the field of personalized medicine for type 1 diabetes, including the latest discoveries in stem cell and gene therapy for the disease, and current obstacles that must be overcome before the dream of personalized medicine for all type 1 diabetes patients can be realized.

Pancreatic Adenocarcinoma: Unconventional Approaches for an Unconventional Disease

This review highlights current treatments, limitations, and pitfalls in the management of pancreatic cancer and discusses current research in novel targets and drug development to overcome these clinical challenges. We begin with a review of the clinical landscape of pancreatic cancer, including genetic and environmental risk factors, as well as limitations in disease diagnosis and prevention. We next discuss current treatment paradigms for pancreatic cancer and the shortcomings of targeted therapy in this disease. Targeting major driver mutations in pancreatic cancer, such as dysregulation in the KRAS and TGFβ signaling pathways, have failed to improve survival outcomes compared with nontargeted chemotherapy; thus, we describe new advances in therapy such as Ras-binding pocket inhibitors. We then review next-generation approaches in nanomedicine and drug delivery, focusing on preclinical advancements in novel optical probes, antibodies, small-molecule agents, and nucleic acids to improve surgical outcomes in resectable disease, augment current therapies, expand druggable targets, and minimize morbidity. We conclude by summarizing progress in current research, identifying areas for future exploration in drug development and nanotechnology, and discussing future prospects for management of this disease.

Genomic Interventions in Medicine

Lately, the term "genomics" has become ubiquitous in many scientific articles. It is a rapidly growing aspect of the biomedical sciences that studies the genome. The human genome contains a torrent of information that gives clues about human origin, evolution, biological function, and diseases. In a bid to demystify the workings of the genome, the Human Genome Project (HGP) was initiated in 1990, with the chief goal of sequencing the approximately 3 billion nucleotide base pairs of the human DNA. Since its completion in 2003, the HGP has opened new avenues for the application of genomics in clinical practice. This review attempts to overview some milestone discoveries that paved way for the initiation of the HGP, remarkable revelations from the HGP, and how genomics is influencing a paradigm shift in routine clinical practice. It further highlights the challenges facing the implementation of genomic medicine, particularly in Africa. Possible solutions are also discussed.

Gene therapy and type 1 diabetes mellitus

BACKGROUND

Type 1 diabetes mellitus (T1DM) is an autoimmune disorder characterized by T cell-mediated self-destruction of insulin-secreting islet β cells. Management of T1DM is challenging and complicated especially with conventional medications. Gene therapy has emerged as one of the potential therapeutic alternatives to treat T1DM. This review primarily focuses on the current status and the future perspectives of gene therapy in the management of T1DM. A vast number of the studies which are reported on gene therapy for the management of T1DM are done in animal models and in preclinical studies. In addition, the safety of such therapies is yet to be established in humans. Currently, there are several gene level interventions that are being investigated, notably, overexpression of genes and proteins needed against T1DM, transplantation of cells that express the genes against T1DM, stem-cells mediated gene therapy, genetic vaccination, immunological precursor cell-mediated gene therapy and vectors.

METHODS

We searched the current literature through searchable online databases, journals and other library sources using relevant keywords and search parameters. Only relevant publications in English, between the years 2000 and 2018, with evidences and proper citations, were considered. The publications were then analyzed and segregated into several subtopics based on common words and content. A total of 126 studies were found suitable for this review.

FINDINGS

Generally, the pros and cons of each of the gene-based therapies have been discussed based on the results collected from the literature. However, there are certain interventions that require further detailed studies to ensure their effectiveness. We have also highlighted the future direction and perspectives in gene therapy, which, researchers could benefit from.

Tumor angiogenesis and anti-angiogenic gene therapy for cancer

When Folkman first suggested a theory about the association between angiogenesis and tumor growth in 1971, the hypothesis of targeting angiogenesis to treat cancer was formed. Since then, various studies conducted across the world have additionally confirmed the theory of Folkman, and numerous efforts have been made to explore the possibilities of curing cancer by targeting angiogenesis. Among them, anti-angiogenic gene therapy has received attention due to its apparent advantages. Although specific problems remain prior to cancer being fully curable using anti-angiogenic gene therapy, several methods have been explored, and progress has been made in pre-clinical and clinical settings over previous decades. The present review aimed to provide up-to-date information concerning tumor angiogenesis and gene delivery systems in anti-angiogenic gene therapy, with a focus on recent developments in the study and application of the most commonly studied and newly identified anti-angiogenic candidates for anti-angiogenesis gene therapy, including interleukin-12, angiostatin, endostatin, tumstatin, anti-angiogenic metargidin peptide and endoglin silencing.

Hydrodynamic IL10 Gene Transfer in Human Colon: Results from an "EX VIVO" Study with Potential Clinical Application in Crohn's Disease

BACKGROUND

The aim of this work is to evaluate the efficacy of hydrodynamic venous IL10 gene delivery to "ex vivo" human colon segments and to determine its potential interest in Crohn's disease treatment.

METHODS

Twenty human colon segments were obtained from surgical resections. Hydrodynamic transfection through the main vein of the pedicle with 50 mL of hIL10 plasmid (20 μg/mL) solution was performed on 13 of them. Tissue sections were cultured and DNA, RNA, and protein copies were determined after 1, 2, and 4 days. Data obtained were compared with 6 nontransfected specimens. Finally, 1 specimen was injected with gold nanoparticles, and their distribution was examined under electron microscope.

RESULTS

IL10 DNA levels were higher in treated tissues than in controls (P < 0.001), decreasing along time. The amount of hIL10 RNA was significantly increased in treated tissues when compared with controls (P = 0.001). The indexes of protein IL10 translation in treated groups were much higher (P < 0.001) than the basal production. The protein expression was higher in transfected tissue (10-50-fold, with respect to control tissue); this difference being established during the first hours and maintained during, at least, 4 days. With electron microscopy, we hardly observed large (15 nm) gold nanoparticles within the tissue, always in the submucosa. However, multiple small (4 nm) nanoparticles were observed within the cytoplasm of enterocytes in mucosa.

CONCLUSIONS

Hydrodynamic procedure efficiently delivers the IL10 gene to the human colon, achieving levels of tissue protein expression high enough to mediate pharmacological effects with interest in controlling immune response in patients with Crohn's disease.

Gene Therapy for Pancreatic Cancer: Specificity, Issues and Hopes

A recent death projection has placed pancreatic ductal adenocarcinoma as the second cause of death by cancer in 2030. The prognosis for pancreatic cancer is very poor and there is a great need for new treatments that can change this poor outcome. Developments of therapeutic innovations in combination with conventional chemotherapy are needed urgently. Among innovative treatments the gene therapy offers a promising avenue. The present review gives an overview of the general strategy of gene therapy as well as the limitations and stakes of the different experimental in vivo models, expression vectors (synthetic and viral), molecular tools (interference RNA, genome editing) and therapeutic genes (tumor suppressor genes, antiangiogenic and pro-apoptotic genes, suicide genes). The latest developments in pancreatic carcinoma gene therapy are described including gene-based tumor cell sensitization to chemotherapy, vaccination and adoptive immunotherapy (chimeric antigen receptor T-cells strategy). Nowadays, there is a specific development of oncolytic virus therapies including oncolytic adenoviruses, herpes virus, parvovirus or reovirus. A summary of all published and on-going phase-1 trials is given. Most of them associate gene therapy and chemotherapy or radiochemotherapy. The first results are encouraging for most of the trials but remain to be confirmed in phase 2 trials.

The Promise of Gene Therapy for Pancreatic Cancer

Unlike for other digestive cancer entities, chemotherapy, radiotherapy, and targeted therapies have, so far, largely failed to improve patient survival in pancreatic adenocarcinoma (PDAC), which remains the fourth leading cause of cancer-related death in Europe and the United States. In this context, gene therapy may offer a new avenue for patients with PDAC. In this review, we explore the research currently ongoing in French laboratories aimed at defeating PDAC using nonviral therapeutic gene delivery, targeted transgene expression, or oncolytic virotherapy that recently or will soon bridge the gap between experimental models of cancer and clinical trials. These studies are likely to change clinical practice or thinking about PDAC management, as they represent a major advance not only for PDAC but may also significantly influence the field of gene-based molecular treatment of cancer.

Functional magnetic Prussian blue nanoparticles for enhanced gene transfection and photothermal ablation of tumor cells

Functional magnetic Prussian blue nanoparticles as a gene carrier and photothermal agent for multi-modal cancer treatment under magnetic targeting.

Preparation and evaluation of polyethylenimine-functionalized carbon nanotubes tagged with 5TR1 aptamer for targeted delivery of Bcl-xL shRNA into breast cancer cells

In this study, single-walled carbon nanotubes (SWCNTs) were covalently attached to poly(ethylene glycol) (PEG) and polyethylenimine (PEI) 10 kDa, or its derivatives, to fabricate efficient carriers for gene delivery. PEI 10 kDa was modified by alkylcarboxylation of its primary amines with a series of ω-bromo-alkylcarboxylic acids to provide a range of vectors with increased lipophilicity. PEI 10 kDa or its alkylcarboxylate derivatives were conjugated to SWCNT-PEG to develop vectors possessing effective DNA condensation ability which can interact with cell membrane via both nano-needle mechanism and electrostatic interactions produced by SWCNT and PEI, respectively. The results demonstrated that SWCNT-PEG-PEI and SWCNT-PEG-derivatives of PEI could condense DNA into particle size less than 150 nm with positive surface charges between 6.3-30.8 mV. To improve the antitumor efficacy, we developed a targeted gene delivery system using a 5 TR1 aptamer. The most efficient vector, which was prepared by attachment of SWCNT-PEG to modified PEI 10 kDa with 10-bromodecanoic acid (10%), showed 8.5-10 folds enhancement in transfection activity at C/P ratio 6 as compared to the gold standard PEI 25 kDa at C/P ratio of 0.8. We also showed that the selected polyplex could efficiently and selectively transfer plasmid shRNA to MUC1 positive cells.

Poly(ethylenimine) conjugated bioreducible dendrimer for efficient gene delivery

Branched poly(ethylenimine) (PEI) 25 kDa is an efficient gene delivery vector with outstanding gene condensation ability and great endosome escape activity. However, it also induces higher cytotoxicity. Transfection efficiency and toxicity of PEI are highly dependent upon their molecular weight and structure. We developed a bioreducible poly(ethylenimine) (PEI (-s-s-)) derived from low molecular weight PEI (1.8 kDa) for efficient gene delivery. Bioreducible core molecule is expected to increase molecular weight and reduce the cytotoxicity of the copolymer. PEI (-s-s-) polyplexes showed higher transfection efficiency and lower cytotoxicity compared to branched PEI 25 kDa, Lipofectamine® 2000 and, FuGENE® 6. In addition, PEI (-s-s-) derivative (16 kDa) formed stable polyplexes with a zeta-potential value of +34 mV and polyplex size of 61 nm. PEI (-s-s-) derivative (16 kDa) showed excellent transfection efficiency: 3.6 times higher than branched PEI 25 kDa in HeLa cells and 7.4 times higher than Lipofectamine® 2000 in H9C2 cell. The derivatives also showed lower cytotoxicity compared with Lipofectamine® 2000 and PEI 25 kDa in various cell types. In addition, newly synthesized PEI (-s-s-) derivatives have high reproducibility.

Targeted oncolytic herpes simplex virus type 1 eradicates experimental pancreatic tumors

As many other cancers, pancreatic ductal adenocarcinoma (PDAC) progression is associated with a series of hallmark changes for cancer cells to secure their own growth success. Yet, these very changes render cancer cells highly sensitive to viral infection. A promising strategy may rely on and exploit viral replication for tumor destruction, whereby infection of tumor cells by a replication-conditional virus may lead to cell destruction and simultaneous release of progeny particles that can spread and infect adjacent tumor cells, while sparing healthy tissues. In the present study, we used Myb34.5, a second-generation replication-conditional herpes simplex virus type 1 (HSV-1) mutant in which ICP6 gene expression is defective and expression of the HSV-1 γ134.5 gene is regulated by the cellular B-myb promoter. We found that B-myb is present in experimental PDAC and tumors, and is overexpressed in patients' tumors, as compared with normal adjacent pancreas. Myb34.5 replicates to high level in human PDAC cell lines and is associated with cell death by apoptosis. In experimental models of PDAC, mice receiving intratumoral Myb34.5 injections appeared healthy and tumor progression was inhibited, with evidence of tumor necrosis, hemorrhage, viral replication, and cancer cell death by apoptosis. Combining standard-of-care chemotherapy with Myb34.5 successfully led to a very impressive antitumoral effect that is rarely achieved in this experimental model, and resulted in a greater reduction in tumor growth than chemotherapy alone. These promising results warrant further evaluation in early phase clinical trial for patients diagnosed with PDAC for whom no effective treatment is available.

Gene therapy in pancreatic cancer

Pancreatic cancer (PC) is a highly lethal disease and notoriously difficult to treat. Only a small proportion of PC patients are eligible for surgical resection, whilst conventional chemoradiotherapy only has a modest effect with substantial toxicity. Gene therapy has become a new widely investigated therapeutic approach for PC. This article reviews the basic rationale, gene delivery methods, therapeutic targets and developments of laboratory research and clinical trials in gene therapy of PC by searching the literature published in English using the PubMed database and analyzing clinical trials registered on the Gene Therapy Clinical Trials Worldwide website (http://www. wiley.co.uk/genmed/ clinical). Viral vectors are main gene delivery tools in gene therapy of cancer, and especially, oncolytic virus shows brighter prospect due to its tumor-targeting property. Efficient therapeutic targets for gene therapy include tumor suppressor gene p53, mutant oncogene K-ras, anti-angiogenesis gene VEGFR, suicide gene HSK-TK, cytosine deaminase and cytochrome p450, multiple cytokine genes and so on. Combining different targets or combination strategies with traditional chemoradiotherapy may be a more effective approach to improve the efficacy of cancer gene therapy. Cancer gene therapy is not yet applied in clinical practice, but basic and clinical studies have demonstrated its safety and clinical benefits. Gene therapy will be a new and promising field for the treatment of PC.

5-aminolevulinic acid-incorporated nanoparticles of methoxy poly(ethylene glycol)-chitosan copolymer for photodynamic therapy

Purpose

The aim of this study was to make 5-aminolevulinic acid (5-ALA)-incorporated nanoparticles using methoxy polyethylene glycol/chitosan (PEG-Chito) copolymer for application in photodynamic therapy for colon cancer cells.

Methods

5-ALA-incorporated (PEG-Chito-5-ALA) nanoparticles were prepared by ion complex formation between 5-ALA and chitosan. Protoporphyrin IX accumulation in the tumor cells and phototoxicity induced by PEG-Chito-5-ALA nanoparticles were assessed using CT26 cells in vitro.

Results

PEG-Chito-5-ALA nanoparticles have spherical shapes with sizes diameters 200 nm. More specifically, microscopic observation revealed a core-shell structure of PEG-Chito-5-ALA nanoparticles. 1H NMR spectra showed that 5-ALA was incorporated in the core of the nanoparticles. In the absence of light irradiation, all components such as 5-ALA, empty nanoparticles, and PEG-Chito-5-ALA nanoparticles did not affect the viability of cells. However, 5-ALA or PEG-Chito-5-ALA nanoparticles induced tumor cell death under light irradiation, and the viability of tumor cells was dose-dependently decreased according to the increase in irradiation time. In particular, PEG-Chito-5-ALA nanoparticles induced increased phototoxicity and higher protoporphyrin IX accumulation into the tumor cells than did 5-ALA alone. Furthermore, PEG-Chito-5-ALA nanoparticles accelerated apoptosis/necrosis of tumor cells, compared to 5-ALA alone.

Conclusion

PEG-Chito-5-ALA nanoparticles showed superior delivery capacity of 5-ALA and phototoxicity against tumor cells. These results show that PEG-Chito-5-ALA nanoparticles are promising candidates for photodynamic therapy of colon cancer cells.

Targeting and killing of metastatic cells in the transgenic adenocarcinoma of mouse prostate model with vesicular stomatitis virus

Vesicular stomatitis virus (VSV) is an oncolytic virus which selectively infects and kills cancer cells. The goal of the present study was to determine whether VSV is capable of targeting metastatic lesions that arise in situ in the transgenic adenocarcinoma of the mouse prostate (TRAMP) model. The interferon (IFN)-responsive luciferase containing VSV(AV3) strain was injected intraprostatically into both control and TRAMP mice. Distribution, infectivity, apoptosis, and status of the IFN response were evaluated at the site of viral injection (prostate), as well as in metastatic lesions (lymph nodes), through plaque, polymerase chain reaction (PCR), and immunohistochemical analysis. Bioluminescence analyses demonstrated that VSV(AV3) persisted at high levels in the prostate region of TRAMP mice for up to 96 hours, but at relatively low levels and for only 48 hours in control mice. Live virus was discovered in the lymph nodes of TRAMP mice, but not in control mice. TUNEL staining revealed increased cell death in VSV(AV3) infected metastatic cells present in the lymph nodes of TRAMP mice. There was an evidence of IFN activation in lymph nodes containing metastatic cells. Our results indicate that intraprostatic injections of VSV(AV3) can be used as a means to infect and kill metastatic lesions associated with advanced prostate cancer.

Regeneration and bioengineering of transplantable abdominal organs: current status and future challenges

INTRODUCTION

The most critical issue to organ transplantation is the identification of new sources of organs. The present manuscript illustrates the state-of-the-art regenerative medicine (RM) investigations aiming to manufacturing abdominal organs for transplant purposes.

AREAS COVERED

This manuscript focuses on research in the bioengineering and regeneration of kidneys, insulin-producing cells, livers and small bowel. The main technology currently under development exploits the seeding of cells on supporting scaffolding material. Despite favorable preliminary results obtained with relatively simple, hollow organs, when more complex organs are considered, the scenario changes dramatically. Investigations are still in early stages, and clinical translation is not yet foreseeable based on current knowledge and information. Obstacles are numerous but we believe the critical factor hampering success is lack of in-depth understanding of the extracellular matrix (ECM) and cell-ECM interactions, as well as the mechanisms with which organs develop in utero.

EXPERT OPINION

The success of RM to generate transplantable abdominal organs relies heavily on progress in (stem) cell therapies, developmental and ECM biology, and in the thorough understanding of the intricate relationship and interplay between cells and the ECM. This will require enormous investments in financial and medical resources, which ideally should be embarked upon by governments, the private sector and academia.

T cells and adoptive immunotherapy: recent developments and future prospects in gastrointestinal oncology

Gastrointestinal oncology is one of the foremost causes of death: the gastric cancer accounts for 10.4% of cancer deaths worldwide, the pancreatic cancer for 6%, and finally, the colorectal cancer for 9% of all cancer-related deaths. For all these gastrointestinal cancers, surgical tumor resection remains the primary curative treatment, but the overall 5-year survival rate remains poor, ranging between 20-25%; the addition of combined modality strategies (pre- or postoperative chemoradiotherapy or perioperative chemotherapy) results in 5-year survival rates of only 30-35%. Therefore, many investigators believe that the potential for making significant progress lies on understanding and exploiting the molecular biology of gastrointestinal tumors to investigate new therapeutic strategies such as specific immunotherapy. In this paper we will focus on recent knowledge concerning the role of T cells and the use of T adoptive immunotherapy in the treatment of gastrointestinal cancers.

Oncolytic viruses in radiation oncology

Oncolytic viruses are investigational cancer treatments. They are currently being assessed as single agents or in combination with standard therapies such as external beam radiotherapy - a DNA damaging agent that is a standard of care for many tumour types. Preclinical data indicate that combinations of oncolytic viruses and radiation therapy are promising, showing additional or synergistic antitumour effects in in vitro and in vivo studies. This interaction has the potential to be multifaceted: viruses may act as radiosensitizing agents, but radiation may also enhance viral oncolysis by increasing viral uptake, replication, gene expression and cell death (apoptosis, autophagy or necrosis) in irradiated cells. Phase I and II clinical trials investigating combinations of viruses and radiation therapy have been completed, paving the way for ongoing phase III studies. The aim of this review is to focus on the therapeutic potential of these combinations and to highlight their mechanistic bases, with particular emphasis on the role of the DNA damage response.

Ultrasound-targeted microbubble destruction mediated herpes simplex virus-thymidine kinase gene treats hepatoma in mice

Objective

The purpose of the study was to explore the anti-tumor effect of ultrasound -targeted microbubble destruction mediated herpes simplex virus thymidine kinase (HSV-TK) suicide gene system on mice hepatoma.

Methods

Forty mice were randomly divided into four groups after the models of subcutaneous transplantation tumors were estabilished: (1) PBS; (2) HSV-TK (3) HSV-TK+ ultrasound (HSV-TK+US); (4) HSV-TK+ultrasound+microbubbles (HSV-TK+US+MB). The TK protein expression in liver cancer was detected by western-blot. Applying TUNEL staining detected tumor cell apoptosis. At last, the inhibition rates and survival time of the animals were compared among all groups.

Results

The TK protein expression of HSV-TK+MB+US group in tumor-bearing mice tissues were significantly higher than those in other groups. The tumor inhibitory effect of ultrasound-targeted microbubble destruction mediated HSV-TK on mice transplantable tumor was significantly higher than those in other groups (p < 0.05), and can significantly improve the survival time of tumor-bearing mice.

Conclusion

Ultrasound-targeted microbubble destruction can effectively transfect HSV-TK gene into target tissues and play a significant inhibition effect on tumors, which provides a new strategy for gene therapy in liver cancer.