Naked DNA injection for liver metastases treatment in rats

Therapeutic targeting of liver cancer with a recombinant DNA vaccine containing the hemagglutinin-neuraminidase gene of Newcastle disease virus via apoptotic-dependent pathways

A total of ~38.6 million mortalities occur due to liver cancer annually, worldwide. Although a variety of therapeutic methods are available, the efficacy of treatment at present is extremely limited due to an increased risk of malignancy and inherently poor prognosis of liver cancer. Gene therapy is considered a promising option, and has shown notable potential for the comprehensive therapy of liver cancer, in keeping with advances that have been made in the development of cancer molecular biology. The present study aimed to investigate the synergistic effects of the abilities of the hemagglutinin neuraminidase protein of Newcastle disease virus (NDV), the pro-apoptotic factor apoptin from chicken anaemia virus, and the interferon-γ inducer interleukin-18 (IL-18) in antagonizing liver cancer. Therefore, a recombinant DNA plasmid expressing the three exogenous genes, VP3, IL-18 and hemagglutinin neuraminidase (HN), was constructed. Flow cytometry, acridine orange/ethidium bromide staining and analysis of caspase-3 activity were performed in H22 cell lines transfected with the recombinant DNA plasmid. In addition, 6-week-old C57BL/6 mice were used to establish a H22 hepatoma-bearing mouse model. Mice tumor tissue was analyzed by immunohistochemistry and scanning electron microscopy. The results of the present study revealed that the recombinant DNA vaccine containing the VP3, IL-18 and HN genes inhibited cell proliferation and induced autophagy via the mitochondrial pathway in vivo and in vitro.

Suicide gene therapy in cancer: where do we stand now? Cancer Lett. 2012;324:160-170. [PMID: 22634584 DOI: 10.1016/j.canlet.2012.05.023]

Suicide gene therapy is based on the introduction into tumor cells of a viral or a bacterial gene, which allows the conversion of a non-toxic compound into a lethal drug. Although suicide gene therapy has been successfully used in a large number of in vitro and in vivo studies, its application to cancer patients has not reached the desirable clinical significance. However, recent reports on pre-clinical cancer models demonstrate the huge potential of this strategy when used in combination with new therapeutic approaches. In this review, we summarize the different suicide gene systems and gene delivery vectors addressed to cancer, with particular emphasis on recently developed systems and associated bystander effects. In addition, we review the different strategies that have been used in combination with suicide gene therapy and provide some insights into the future directions of this approach, particularly towards cancer stem cell eradication.

Inhibition of adjuvant arthritis in rats by electroporation with interleukin-1 receptor antagonist

To assess the protective effects of the cytokine inhibitor interleukin-1 receptor antagonist (IL-1ra) on gene induction, an electroporation technique to treat adjuvant-induced arthritis (AIA) in rats was established, and its advantage was estimated in the present study. Electroporation with human IL-1ra was performed in Lewis rats before and after induction of AIA. Local inflammation was evaluated by monitoring hind paw swelling, whereas histological evaluations were performed using paraffin embedded sections of hind paw specimens stained with hematoxylin and eosin. In addition, serum IL-1? levels were analyzed using an enzyme-linked immunosorbent assay. Induction of IL-1ra by our electroporation method inhibited systematic body weight loss and enhancement of local inflammation after intradermal injection of heat-killed Mycobacterium tuberculosis. Notably, IL-1ra electroporation reduced paw swelling, inflammation, and bone erosion scores in embedded sections and serum IL-1? levels induced in AIA rats. The IL-1ra gene induction using the present electroporation technique inhibited local and systematic inflammation in AIA rats. These results indicate that this method may represent a novel pharmacotherapy strategy for arthritis.

Ultrasound-mediated interferon β gene transfection inhibits growth of malignant melanoma

We investigated the effects of ultrasound-mediated transfection (sonotransfection) of interferon β (IFN-β) gene on melanoma (C32) both in vitro and in vivo. C32 cells were sonotransfected with IFN-β in vitro. Subcutaneous C32 tumors in mice were sonicated weekly immediately after intra-tumor injection with IFN-β genes mixed with microbubbles. Successful sonotransfection with IFN-β gene in vitro was confirmed by ELISA, which resulted in C32 growth inhibition. In vivo, the growth ratio of tumors transfected with IFN-β gene was significantly lower than the other experimental groups. These results may lead to a new method of treatment against melanoma and other hard-to-treat cancers.

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

BACKGROUND

Gene therapy consists of the introduction of genetic material into cells for a therapeutic purpose. A wide range of gene therapy vectors have been developed and used for applications in gastrointestinal oncology.

AIM

To review recent developments and published clinical trials concerning the application of gene therapy in the treatment of liver, colon and pancreatic cancers.

METHODS

Search of the literature published in English using the PubMed database.

RESULTS

A large variety of therapeutic genes are under investigation, such as tumour suppressor, suicide, antiangiogenesis, inflammatory cytokine and micro-RNA genes. Recent progress concerns new vectors, such as oncolytic viruses, and the synergy between viral gene therapy, chemotherapy and radiation therapy. As evidence of these basic developments, recently published phase I and II clinical trials, using both single agents and combination strategies, in adjuvant or advanced disease settings, have shown encouraging results and good safety records.

CONCLUSIONS

Cancer gene therapy is not yet indicated in clinical practice. However, basic and clinical advances have been reported and gene therapy is a promising, new therapeutic approach for the treatment of gastrointestinal tumours.

Sonoporation-mediated gene transfer into adult rat dorsal root ganglion cells

Background

Gene transfer into many cell types has been successfully used to develop alternative and adjunct approaches to conventional medical treatment. However, effective transfection of postmitotic neurons remains a challenge. The aim of this study was to develop a method for gene transfer into rat primary dorsal root ganglion neurons using sonoporation.

Methods

Dissociated cells from adult rat dorsal root ganglion (DRG) cells were sonicated for 1-8 s at 2.5-10 W to determine the optimal ultrasound duration and power for gene transfection and cell survival. Transfection efficiency was compared between sonoporation, liposome and lentiviral vector gene transfer techniques.

Results

The optimum ultrasound intensity was 5 W for 2 s and yielded an efficiency of gene transfection of 31% and a survival rate of 35%.

Conclusions

Sonoporation can be optimized to minimize cell death and yield a high percentage of transfected neurons and that this technique can be easily applied to primary cultures of rat dorsal root ganglion neurons.

Differences in gene expression between sonoporation in tumor and in muscle

BACKGROUND

Ultrasound (US) is a novel and effective tool for the local delivery of genes into target tissues. US can temporarily change the permeability of a cell membrane and thus enhance the delivery of naked DNA into cells. In the present study, the efficiencies of gene expression mediated by US delivery in orthotopic liver tumor, subcutaneous tumor and muscle tissue were evaluated by changing the contrast agent concentrations and US exposure durations.

METHODS

Plasmid DNA coding for luciferase, interleukin-12 or enhanced green fluorescence protein was mixed with SonoVue and injected intratumorally or intramuscularly. The injection sites were then exposed to US (20% duty cycle and 0.4 W/cm(2) intensity).

RESULTS

The results obtained showed that the optimal condition was 50% SonoVue for tumors and 30% for muscle, with 10 min of US exposure. The expression levels of the transfected DNAs were in the order: muscle > subcutaneous tumor > orthotopic liver tumor.

CONCLUSIONS

The present study indicates that muscle tissue is a good target site for producing large amounts of gene products for the purpose of gene therapy.

A combined chemoimmunotherapy approach using a plasmid-doxorubicin complex

We report a combined chemoimmunotherapy vehicle consisting of plasmid loaded with doxorubicin and evaluate its efficacy in two different tumor models. A stable complex was formed with a 1300:1 ratio of doxorubicin bound to native plasmid via intercalation. Pharmacokinetics of the complex showed much slower clearance from plasma up to 3 h compared to 10 min for free doxorubicin. In mice bearing NCI-H358 xenografts, lower doses of complex (doxorubicin 0.5 mg/kg, plasmid 4 mg/kg) effectively reduced tumor growth compared to high doses (5 mg/kg) of free doxorubicin (68% versus 77%). Similar results were observed in mice bearing 4T1 murine allografts; the complex (doxorubicin 2 mg/kg, plasmid 8 mg/kg) was effective and caused similar reduction of tumor compared to free doxorubicin (4 mg/kg) (47% versus 46%). The complex showed no signs of severe systemic toxicity or cardiotoxicity compared to the free doxorubicin in mice as indicated by body weights and heart tissue histology. Elevated levels of cytokines (IL-12, IL-6, and IFN-gamma) were observed in serum as well as in tumor tissue after intravenous injection of complex when compared to plasmid or doxorubicin alone. This approach simultaneously delivers both chemotherapeutic and immunotherapeutic agents without time delay, improves pharmacokinetics of the free drug, lowers drug toxicity, upregulates a variety of cytokines, and is effective against different tumors.

Cellular and molecular events associated with the antitumor response induced by the cytosine deaminase/5-fluorocytosine suicide gene therapy system in a rat liver metastasis model

The bacterial cytosine deaminase (CD) gene converts the non-toxic prodrug 5-fluorocytosine (5-FC) into 5-fluorouracil. We have previously shown, in a rat liver metastasis model from colon carcinoma, that intratumoral injection of a CD-expressing plasmid into the animals followed by 5-FC treatment results in the regression of the treated tumor as well as distant uninjected tumors. The aim of this study was to further analyze the mechanisms associated with tumor regression induced upon application of suicide CD/5-FC strategy. Tumor regression was associated with an increased apoptosis, the recruitment of natural killer cells, CD4- and CD8 T lymphocytes within the tumors and an increased expression of several cytokines/chemokines mRNAs. These data indicate that the CD/5-FC suicide strategy is associated with the triggering of cellular and molecular events leading to an efficient antitumor immune response involving both innate and acquired immunity.

Nonviral Jet-Injection Gene Transfer for Efficient in Vivo Cytosine Deaminase Suicide Gene Therapy of Colon Carcinoma

Jet-injection technology has developed into an efficient gene delivery system for nonviral in vivo gene transfer. In this study the jet-injector system was used for the intratumoral gene transfer of small volumes of naked DNA encoding the Escherichia coli cytosine deaminase (CD) suicide gene. In our in vivo studies human colon carcinoma (patient-derived tumor model Colo5734 and SW480 colon carcinoma)-bearing NMRI-nu/nu male mice received four jet injections (10 microl per injection) of the CD-gene-carrying plasmid, representing 40 microg plasmid DNA per animal. Forty-eight hours after jet-injection, treatment of tumors with 5-fluorocytosine (5-FC; 500 mg/kg ip) was started and during treatment tumor volumes were measured. Starting from day 5 of 5-FC treatment inhibition of tumor growth was seen in the CD-gene-transduced tumors compared to the respective control groups, which lasted for the entire observation time. Expression analysis at the mRNA and protein levels revealed efficient expression of the CD gene in the jet-injected tumors. Therefore, in this in vivo study jet-injection gene transfer of 40 microg CD-expressing naked plasmid DNA leads to a significant tumor growth inhibition. This study demonstrates the applicability of the jet-injection technology for in vivo gene transfer into tumors to achieve efficient tumor gene therapy.

Regulatory sequences of H19 and IGF2 genes in DNA-based therapy of colorectal rat liver metastases

BACKGROUND

Malignant tumors of the liver are among the most common causes of cancer-related death throughout the world. Current therapeutic approaches fail to control the disease in most cases. This study seeks to explore the potential utility of transcriptional regulatory sequences of the H19 and insulin growth factor 2 (IGF2) genes for directing tumor-selective expression of a toxin gene (A fragment of diphtheria toxin), delivered by non-viral vectors.

METHODS

The therapeutic potential of the toxin vectors driven by the H19 and the IGF2-P3 regulatory sequences was tested in a metastatic model of rat CC531 colon carcinoma in liver.

RESULTS

Intratumoral injection of these vectors into colon tumors implanted in the liver of rats induced an 88% and a 50% decrease respectively in the median tumor volume as compared with the control groups. This therapeutic action was accompanied by increased necrosis of the tumor. Importantly, no signs of toxicity were detected in healthy animals after their treatment by the toxin expression vectors.

CONCLUSIONS

DT-A was preferentially expressed in liver metastases after being transfected with H19 or IGF2-P3 promoter-driven DT-A expression plasmids, causing a very significant inhibition of tumor growth as a result of its cytotoxic effect. Our findings strongly support the feasibility of our proposed therapeutic strategy, which may contribute to open new gene therapeutic options for human liver metastases.

Gene therapy for hepatocellular carcinoma using sonoporation enhanced by contrast agents

We examined whether sonoporation enhanced by a contrast agent (BR14) was effective in gene therapy for hepatocelluar carcinoma (HCC). Human hepatic cancer cells (SK-Hep1) and plasmid cDNAs expressing green fluorescent protein (GFP), interferonbeta (IFNbeta), and LacZ were used. In vitro, SK-Hep1 cell suspensions with DNA and BR14 were sonoporated. Expressions of every plasmid cDNA and the antitumor effect of IFNbeta were analyzed. In vivo, GFP and IFNbeta genes with BR14 were directly injected into subcutaneous tumors using SK-Hep1 in nude mice, and transcutaneous sonoporation of the tumors was performed. GFP gene transfections and tumor diameters after IFNbeta gene transfection were examined. In vitro, no SK-Hep1 cells were transfected without sonication, whereas transfections were successful after sonication with BR14. Antitumor effect of IFNbeta gene transfection by ultrasound (US) and with BR14 was revealed. In vivo, the SK-Hep1 cells expressed GFP, and the IFNbeta gene transfection by US with BR14 reduced tumor size significantly. In conclusion, gene therapy with sonoporation enhanced by a contrast agent may become a new treatment option for HCC.

Mechanism of thermochemotherapy with 5-fluorocytosine on human colon cancer cell line SW480 transfected cytosine deaminase gene

AIM: To investigate the mechanism of thermochemotherapy with 5-fluorocytosine (5-FC) on human colon cancer cell line SW480 transfected carcinoembryonic antigen (CEA) tissue-specific cytosine deaminase (CD) in vitro.

METHODS: Recombinant retroviral vector G1CEACDNa, in which the CD gene was controlled under the CEA promoter, was introduced through liposome technique to human colorectal carcinoma cell line SW480, and then the cells were selectively cultured in G418. The proliferated colonies were treated with the combined therapy of 5-FC and hyperthermia at a temperature of 43 ℃ for 30 min, 3 times. RT-PCR was performed to detect the expression of CD gene in target cells after being heated. The cell survival rate was detected by MTT method. The ultrastructures of cells were observed by electron microscopy and apoptosis was verified by flow cytometry.

RESULTS: The expression of CD genes in target cells was detected after being heated. After transfection, SW480-CEACD cells were more sensitive than their parental cells (P <0.01, t = 5.620, n = 9) to 5-FC, the killing effect of hyperthermia on SW480 cells was observed (P <0.05, t = 2.999, n = 9). Furthermore, after being treated with thermoche-motherapy of 5-FC at a temperature of 43 ℃ for 30 min, the killing effect on SW480-CEACD cells was more significant than that on SW480 cells (P <0.01, t = 4.356, n = 9). Treatment with the combination of 5-FC and hyperthermia displayed a higher anti-tumor effect than that with 5-FC alone on SW480-CEACD cells in vitro (P <0.05, t = 2.376, n = 9). Apoptotic bodies in the field of electron microscope were observed. G1 blockage was confirmed and the increased rate of apoptosis cells was verified after hyperthermia with 5-FC by flow cytometry.

CONCLUSION: The combination of 5-FC and hyperthermia will result in G1 blockage of human colorectal carcinoma cell lines SW480 transfected with the CEA tissue-specific CD genes, which will improve the outcome of the anti-tumor effect on that cell line.

Targeted nucleic acid delivery into tumors: new avenues for cancer therapy

Unique properties of tumors, such as abnormalities in the cell cycle and apoptosis, migration and metastasis, neoangiogenesis or unique antigen profiles are targets for therapeutic anti-cancer strategies. Beyond the selection of such strategies, additional specificity for the targeted tumor tissue can be accomplished in cancer gene therapy in several ways. Upon systemic administration, appropriately packaged therapeutic nucleic acid may be preferentially transported into the tumor tissue (targeted delivery); formulation can mediate the intracellular uptake of the nucleic acid into the nucleus of target cells only (transductional targeting); and/or the use of specific promotor/enhancer elements can restrict transcription of therapeutic genes to the target cells only (transcriptional targeting). Options for physical and biological targeting of nucleic acid formulations into tumors and therapeutic approaches are reviewed.

Gastrin receptor antagonist combined with cytosine deaminase suicide gene therapy enhances killing of colorectal carcinoma

AIM

To investigate the killing effect of cytosine deaminase/5-fluorocytosine on colorectal carcinoma when combined with gastrin receptor antagonist.

METHODS

Plasmid G1CEACDNa was transferred into the LoVo cell line using liposomes method. The growth curve of cells was observed when cultured with 5-FC (1 mmol/L) or/and CI-988 (1×10^-8mmol/L) in RPMI-1 640+100 ml/L fatal bovine serum. The killing efficiency was measured by MTT method. The submicroscopic structure of cells was observed by electron microscope, apoptosis was verified by a flow cytometer . CD⁺ LoVo cells were were. inoculated s.c. in athymic nude mice followed by 5-fluorocysine or/and CI-988 treatment for 20 d. these nude mice were killed with their tumor weight determined. Then tumor tissue was stained with hematoxylin and eosin, the submicroscopic structure of cells was observed by electron microscope.

RESULTS

After treated with 5-FC or CI-988,the inhibition rate of CD⁺ LoVo cells was 90 % and 50 %, respectively. When c these two reagents were used in combination, the inhibition rate was 40 % and 97 % on 3 d and 6 d, respectively. By MTT method, combination of CD/5-FC and CI-988 possessed superior killing effect in comparison to single therapy (0.53±0.05 vs 0.49±0.02, 0.38±0.06, F =29.5536, n =5, P <0.01). Electron microscope and flow cytometer verified that cells were apoptosized after exposed to 5-FC (1 mmol/L) and CI-988(1×10^-8 mmol/L) 72 h. Significant anti-tumor effect was observed in nude mice bearing CD+ LoVo cells followed with 5-FC(500mg/kg body weight i.p. injection per day) or CI-988 (10 mg/kg per day orally), the inhibition rate were 69.4% and 49.5%,respectively. When these two reagents were used in combination, the inhibition rate was 81.5 % that was higher compared to single therapy (0.42±0.12 vs 0.69±0.11, 1.22±0.22, F =33.1709, n =5, P <0.05).There were apoptosis bodies in submicroscopic structure.

CONCLUSION

Gastrin receptor antagonist canelevate the killing effect of CD/5-FC on colorectal carcinoma. Apoptosis is possibly one of the reasons of the synergistic action.

Killing effect of CD/5-FC system on human colon cancer cell lines SW 480 and LoVo

AIM

To investigate the killing effect of carcinoembryonic antigen (CEA) and tissue-specific cytosine deaminase (CD)/5-fluorocytosine (5-FC) system on human colorectal carcinoma cell lines LoVo and SW480 in vitro.

METHODS

Recombinant retroviral vector G1CEACDNa was constructed, in which the CD gene was controlled under the CEA promoter, and retroviral vector pCD2 were introduced through liposome technique respectively to the human colorectal carcinoma cell lines LoVo and SW480. Expression of CEA was high and low in both the cell lines respectively. The cells were selectively cultured in G418. The proliferative colonies were treated with 5-FC.

RESULTS

After the transfection, LoVo-CEACD cells and LoVo-CD cells were more sensitive to 5-FC than their parental cells (P<0.01, t = 5.688, n = 9; P<0.01, t = 3.136, n = 9), and SW480-CEACD cells and SW480-CD cells were more sensitive than their parental cells as well (P<0.01, t = 3.437, n = 9; P <0.01, t = 3.516, n = 9). Furthermore, the LoVo-CEACD cells were more sensitive to 5-FC than the LoVo-CD cells (P <0.05, t =2.183, n =9) while the SW480-CEACD cells were less sensitive than SW480-CD cells.TheLoVo-CEACD cells displayed a higher anti-tumor effect than SW480-CEACD cells in vitro. The bystander effect in all cells transfected with CD gene were observed in this study.

CONCLUSION

The CEA tissue-specific CD/5-FC system displays an obvious targeting anti-tumor effect on human colorectal carcinoma cell lines LoVo and SW480, but the killing effect on the LoVo-CEACD cells is higher than that on the SW480-CEACD cells in vitro.