PURPOSE: In the present study, human neural stem cells (hNSCs) with tumor-tropic behavior were used as drug delivery vehicle to selectively target melanoma. A hNSC line (HB1.F3) was transduced into two types: one expressed only the cytosine deaminase (CD) gene (HB1.F3. CD) and the other expressed both CD and human interferon-β (IFN-β) genes (HB1.F3.CD. IFN-β). MATERIALS AND METHODS: This study verified the tumor-tropic migratory competence of engineered hNSCs on melanoma (A375SM) using a modified Boyden chamber assay in vitro and CM-DiI staining in vivo. The antitumor effect of HB1.F3.CD and HB1.F3.CD.IFN-β on melanoma was also confirmed using an MTT assay in vitro and xenograft mouse models. RESULTS: A secreted form of IFN-β from the HB1.F3.CD.IFN-β cells modified the epithelial-mesenchymal transition (EMT) process and metastasis of melanoma. 5-Fluorouracil treatment also accelerated the expression of the pro-apoptotic protein BAX and decelerated the expression of the anti-apoptotic protein Bcl-xL on melanoma cell line. CONCLUSION: Our results illustrate that engineered hNSCs prevented malignant melanoma cells from proliferating in the presence of the prodrug, and the form that secreted IFN-β intervened in the EMT process and melanoma metastasis. Hence, neural stem cell-directed enzyme/prodrug therapy is a plausible treatment for malignant melanoma.
Animals ; Cell Line ; Cytosine Deaminase ; Epithelial-Mesenchymal Transition ; Flucytosine ; Fluorouracil ; Heterografts ; Humans ; In Vitro Techniques ; Melanoma ; Mental Competency ; Mice ; Neoplasm Metastasis ; Neural Stem Cells ; Stem Cells

PURPOSE: Genetically engineered stem cells may be advantageous for gene therapy against various human cancers due to their inherent tumor-tropic properties. In this study, genetically engineered human neural stem cells (HB1.F3) expressing Escherichia coli cytosine deaminase (CD) (HB1.F3.CD) and human interferon-β (IFN-β) (HB1.F3.CD.IFN-β) were employed against lymph node–derived metastatic colorectal adenocarcinoma. MATERIALS AND METHODS: CD can convert a prodrug, 5-fluorocytosine (5-FC), to active 5-fluorouracil, which inhibits tumor growth through the inhibition of DNA synthesis,while IFN-β also strongly inhibits tumor growth by inducing the apoptotic process. In reverse transcription polymerase chain reaction analysis, we confirmed that HB1.F3.CD cells expressed the CD gene and HB1.F3.CD.IFN-β cells expressed both CD and IFN-β genes. RESULTS: In results of a modified trans-well migration assay, HB1.F3.CD and HB1.F3.CD.IFN-β cells selectively migrated toward SW-620, human lymph node–derived metastatic colorectal adenocarcinoma cells. The viability of SW-620 cells was significantly reduced when co-cultured with HB1.F3.CD or HB1.F3.CD.IFN-β cells in the presence of 5-FC. In addition, it was found that the tumor-tropic properties of these engineered human neural stem cells (hNSCs) were attributed to chemoattractant molecules including stromal cell-derived factor 1, c-Kit, urokinase receptor, urokinase-type plasminogen activator, and C-C chemokine receptor type 2 secreted by SW-620 cells. In a xenograft mouse model, treatment with hNSC resulted in significantly inhibited growth of the tumor mass without virulent effects on the animals. CONCLUSION: The current results indicate that engineered hNSCs and a prodrug treatment inhibited the growth of SW-620 cells. Therefore, hNSC therapy may be a clinically effective tool for the treatment of lymph node metastatic colorectal cancer.
Adenocarcinoma* ; Animals ; Chemokine CXCL12 ; Colorectal Neoplasms ; Cytosine Deaminase* ; Cytosine* ; DNA ; Escherichia coli ; Flucytosine ; Fluorouracil ; Genetic Therapy ; Heterografts* ; Humans ; Interferon-beta ; Lymph Nodes ; Lymphatic Metastasis ; Mice* ; Neural Stem Cells* ; Polymerase Chain Reaction ; Reverse Transcription ; Stem Cells ; Urokinase-Type Plasminogen Activator

BACKGROUNDHuman sulfatase-1 (Hsulf-1) is an endosulfatase that selectively removes sulfate groups from heparan sulfate proteoglycans (HSPGs), altering the binding of several growth factors and cytokines to HSPG to regulate cell proliferation, cell motility, and apoptosis. We investigated the role of combined cancer gene therapy with Hsulf-1 and cytosine deaminase/5-fluorocytosine (CD/5-FC) suicide gene on a hepatocellular carcinoma (HCC) cell line, HepG2, in vitro and in vivo.

METHODSReverse transcription polymerase chain reaction and immunohistochemistry were used to determine the expression of Hsulf-1 in HCC. Cell apoptosis was observed through flow cytometry instrument and mechanism of Hsulf-1 to enhance the cytotoxicity of 5-FC against HCC was analyzed in HCC by confocal microscopy. We also establish a nude mice model of HCC to address the effect of Hsulf-1 expression on the CD/5-FC suicide gene therapy in vivo.

RESULTSA significant decrease in HepG2 cell proliferation and an increase in HepG2 cell apoptosis were observed when Hsulf-1 expression was combined with the CD/5-FC gene suicide system. A noticeable bystander effect was observed when the Hsulf-1 and CD genes were co-expressed. Intracellular calcium was also increased after HepG2 cells were infected with the Hsulf-1 gene. In vivo studies showed that the suppression of tumor growth was more pronounced in animals treated with the Hsulf-1 plus CD than those treated with either gene therapy alone, and the combined treatment resulted in a significant increase in survival.

CONCLUSIONSHsulf-1 expression combined with the CD/5-FC gene suicide system could be an effective treatment approach for HCC.

Animals ; Apoptosis ; drug effects ; genetics ; Carcinoma, Hepatocellular ; enzymology ; metabolism ; Cell Movement ; drug effects ; genetics ; Cell Proliferation ; drug effects ; genetics ; Cytosine Deaminase ; genetics ; metabolism ; Flucytosine ; pharmacology ; Genetic Therapy ; Hep G2 Cells ; Humans ; Liver Neoplasms ; enzymology ; metabolism ; Sulfatases ; genetics ; metabolism

Carcinoma, Hepatocellular ; genetics ; therapy ; Cytosine Deaminase ; genetics ; Genetic Therapy ; methods ; Hep G2 Cells ; Humans ; Liver Neoplasms ; genetics ; therapy ; Promoter Regions, Genetic

Human mesenchymal stem cells (MSCs) have emerged as attractive cellular vehicles to deliver therapeutic genes for ex-vivo therapy of diverse diseases; this is, in part, because they have the capability to migrate into tumor or lesion sites. Previously, we showed that MSCs could be utilized to deliver a bacterial cytosine deaminase (CD) suicide gene to brain tumors. Here we assessed whether transduction with a retroviral vector encoding CD gene altered the stem cell property of MSCs. MSCs were transduced at passage 1 and cultivated up to passage 11. We found that proliferation and differentiation potentials, chromosomal stability and surface antigenicity of MSCs were not altered by retroviral transduction. The results indicate that retroviral vectors can be safely utilized for delivery of suicide genes to MSCs for ex-vivo therapy. We also found that a single retroviral transduction was sufficient for sustainable expression up to passage 10. The persistent expression of the transduced gene indicates that transduced MSCs provide a tractable and manageable approach for potential use in allogeneic transplantation.
Adolescent ; Animals ; Cell Death/drug effects ; Cell Line, Tumor ; Cell Proliferation/drug effects ; Cell Transformation, Neoplastic/drug effects/pathology ; Child ; Cytosine Deaminase/*genetics/therapeutic use ; Fluorouracil/pharmacology ; Genetic Therapy ; Genomic Instability/drug effects ; Humans ; Karyotype ; Mesenchymal Stromal Cells/*cytology/drug effects/metabolism ; Mice ; Multipotent Stem Cells/cytology/drug effects/metabolism ; Neoplasms/therapy ; Retroviridae/*metabolism ; Time Factors ; *Transduction, Genetic

OBJECTIVES: Based on studies of the extensive tropism of neural stem cells (NSCs) toward malignant brain tumor, we hypothesized that NSCs could also target head and neck squamous cell carcinoma (HNSCC) and could be used as a cellular therapeutic delivery system. METHODS: To apply this strategy to the treatment of HNSCC, we used a human NSC line expressing cytosine deaminase (HB1.F3-CD), an enzyme that converts 5-fluorocytosine (5-FC) into 5-fluorouracil (5-FU), an anticancer agent. HB1. F3-CD in combination with 5-FC were cocultured with the HNSCC (SNU-1041) to examine the cytotoxicity on target tumor cells in vitro. For in vivo studies, an HNSCC mouse model was created by subcutaneous implantation of human HNSCC cells into athymic nude mice. HB1.F3-CD cells were injected into mice using tumoral, peritumoral, or intravenous injections, followed by systemic 5-FC administration. RESULTS: In vitro, the HB1.F3-CD cells significantly inhibited the growth of an HNSCC cell line in the presence of the 5-FC. Independent of the method of injection, the HB1.F3-CD cells migrated to the HNSCC tumor, causing a significant reduction in tumor volume. In comparison to 5-FU administration, HB1.F3-CD cell injection followed by 5-FC administration reduced systemic toxicity, but achieved the same level of therapeutic efficacy. CONCLUSION: Transplantation of human NSCs that express the suicide enzyme cytosine deaminase combined with systemic administration of the prodrug 5-FC may be an effective regimen for the treatment of HNSCC.
Animals ; Brain Neoplasms ; Carcinoma, Squamous Cell ; Cell Line ; Cytosine Deaminase ; Flucytosine ; Fluorouracil ; Head ; Head and Neck Neoplasms ; Humans ; Injections, Intravenous ; Mice ; Mice, Nude ; Molecular Targeted Therapy ; Neck ; Neural Stem Cells ; Suicide ; Transplants ; Tropism ; Tumor Burden

5-Flucytosine (5-FC) could be changed to 5-fluorouracil (5-FU) by cytosine deaminase (CD), the latter is able to kill cancer cells. However, there is no efficient method to deliver the CD gene into the tumor cells, which hampers the application of the suicide gene system. In this experiment, for the first time, the NDV has been utilized as a vector to deliver the CD gene into the cancer cells, the virus can infect the cancer cells specifically, replicate and assemble, while the cytosine deaminase is expressed. Then the CD converts the prodrug 5-FC into 5-FU to achieve the purpose of inhibiting tumor. Firstly, the whole genome of E. coli JM109 was extracted, and the CD gene was obtained by cloning method. Then the CD and IRES-EGFP were ligated into the pEE12.4 expression vector to become a recombinant pEE12.4IE-CD eukaryotic expression plasmid. The human liver cancer cells were transfected with the plasmid. The cells were treated with different concentrations of 5-FC, MTT method was used to determine the killing effect of CD/5-FC system on the human liver cancer cells. The cell deaths were 18.07%, 42.98% and 62.20% respectively when the concentrations of prodrug were at 10, 20 and 30 mmol x L(-1). In 5-FC acute toxicity experiment, Kunming mice were injected with different concentrations of 5-FC at intervals of 1:0.5. The LD50 of 5-FC through iv injection was determined by improved Karber's method, the LD50 was 507 mg x kg(-1) and the 95% confidence limit was 374-695 mg x kg(-1). According to the maximum LD0 dose of the LD50, the maximum safe dose was 200 mg x kg(-1). Body weight and clinic symptoms of the experimental animals were observed. These results laid the foundation to verify the antitumor effect and safety of CD/5-FC system in animal models. The CD gene was ligated into the NDV (rClone30) carrier, then the tumor-bearing animal was established to perform the tumor inhibiting experiment. The result showed that the recombinant rClone30-CD/5-FC system has a high antitumor activity in vivo. To summarize, CD gene has been cloned and its bioactivity has been confirmed in the mammalian cells. It is the first time in this study to utilize the recombinant NDV to deliver the CD gene into the tumor cells; our result proves the rClone30-CD/5-FC system is a potential method for cancer therapy.
Animals ; Antimetabolites, Antineoplastic ; metabolism ; pharmacology ; Cell Death ; drug effects ; Chick Embryo ; Cytosine Deaminase ; genetics ; metabolism ; Escherichia coli ; genetics ; metabolism ; Flucytosine ; metabolism ; pharmacology ; Fluorouracil ; metabolism ; pharmacology ; Genetic Vectors ; Hep G2 Cells ; Humans ; Lethal Dose 50 ; Liver Neoplasms, Experimental ; pathology ; Mice ; Newcastle disease virus ; genetics ; Plasmids ; Recombinant Proteins ; genetics ; metabolism ; Transfection ; Tumor Burden ; drug effects

OBJECTIVETo study the inhibitory effect of adenovirus-mediated fusion gene system driven by KDR promoter on the proliferation of human gastric adneocarcinoma SCG7901 cells and observe the bystander effect in vitro.

METHODSSCG7901, ECV304 and HepG2 cells were infected with Ad-KDR-CDglyTK and Ad-CMV-CDglyTK at a multiplicity of infection (MOI) of 100, and the infection efficiency and the mRNA expressions of the transferred fusion gene were investigated. GCV and/or 5-FC at different concentrations were added into the culture medium of the infected cells to observe the targeted antitumor effect and bystander effect of CDglyTK suicide gene driven by KDR promoter.

RESULTSWith the MOI of the adenovirus of 100, the fluorescence emitted by green fluorescent protein (GFP) was observed in 95% of the infected SCG7901, ECV304 and HepG2 cells. All the cells infected by Ad-CMV-CDglyTK and SCG7901 and ECV304 cells infected by Ad-KDR-CDglyTK were highly sensitive to the prodrugs. In comparison, HepG2 cells infected with Ad-KDR-CDglyTK did not show much sensitivity to the two prodrugs. Following treatment with the prodrugs at the same concentration, the infected SCG7901 and ECV304 cells exhibited gradually lowered survival rates as the culture time was prolonged, whereas the transgenic HepG2 cells showed no such time-dependent changes. When the non-infected cells were cocultured with the transgenic cells, the bystander effect of CDglyTK gene was observed, which increased with the ratio of the transgenic cells. In these mixed cell culture systems, GCV and 5-FC showed obvious synergetic effect in suppressing the cell survival.

CONCLUSIONThe CDglyTK fusion gene system driven by KDR promoter can inhibit the proliferation of SCG7901 and ECV304 cells with obvious bystander effect in vitro. The combination of the prodrugs produces obvious synergetic effect against the cell survival.

Adenocarcinoma ; genetics ; pathology ; therapy ; Adenoviridae ; genetics ; metabolism ; Cell Line, Tumor ; Cytosine Deaminase ; biosynthesis ; genetics ; Genes, Transgenic, Suicide ; genetics ; Genetic Therapy ; Genetic Vectors ; genetics ; Humans ; Promoter Regions, Genetic ; genetics ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; Stomach Neoplasms ; genetics ; pathology ; therapy ; Thymidine Kinase ; biosynthesis ; genetics ; Vascular Endothelial Growth Factor Receptor-2 ; genetics ; metabolism

OBJECTIVETo evaluate the effect of adenovirus-mediated CD/TK double suicide gene system on tumor growth and cytokine levels in the tumor microenvironment in mice bearing transplanted colorectal cancer.

METHODSCT26 cells were implanted subcutaneously into 30 Balb/c mice, which were subsequently randomized into the control (n=15) and experimental group (n=15). After the tumor formation, CD/TK double suicide gene system was administered for tumor treatment, and the changes in the tumor volume, tumor inhibition rate, and levels of cytokines in the tumor microenvironment were investigated.

RESULTSCD/TK double suicide gene system resulted in a significant inhibition of the tumor growth and significantly increased levels of such cytokines as IL-2, IL-10, TNFalpha and IFNgamma in the tumor microenvironment.

CONCLUSIONCD/TK double suicide gene system produces significant tumor inhibition effect and causes obvious cytokine changes in the tumor microenvironment in mice bearing transplanted colorectal cancer.

Adenoviridae ; genetics ; metabolism ; Animals ; Cell Proliferation ; Colorectal Neoplasms ; metabolism ; pathology ; therapy ; Cytokines ; metabolism ; Cytosine Deaminase ; genetics ; metabolism ; Female ; Genes, Transgenic, Suicide ; genetics ; Genetic Therapy ; methods ; Green Fluorescent Proteins ; genetics ; metabolism ; Interleukin-2 ; metabolism ; Male ; Mice ; Mice, Inbred BALB C ; Neoplasm Transplantation ; Random Allocation ; Recombinant Fusion Proteins ; genetics ; metabolism ; Thymidine Kinase ; genetics ; metabolism ; Tumor Necrosis Factor-alpha ; metabolism ; Vascular Endothelial Growth Factor A ; genetics ; metabolism

OBJECTIVETo study the selective killing effect of adenovirus (Ad)-mediated double suicide gene system driven by the KDR promoter (KDR-CDglyTK) on human colon adneocarcinoma SW480 cells.

METHODSKDR-expressing SW480 cells and LS174T cells that did not express KDR were infected by KDR-CDglyTK, and the infection efficiency and the expression of CDglyTK in the cells were detected by RT-PCR. The infected cells were treated with the prodrugs 5-FC and GCV at different concentrations, and the cell-killing effects and bystander effects were evaluated by MTT method. DNA content and the cell cycle changes in SW480 cells were detected by flow cytometry.

RESULTSThe expression of green fluorescent protein (GFP) was observed in 95% of the infected SW480 and LS174T cells with a multiplicity of infection (MOI) of 100. RT- PCR demonstrated that the product of CD/TK gene existed in SW480 cells infected by Ad- KDR- CD/TK, but not in infected LS174 cells. The infected SW480 cells exhibited high sensitivity to the prodrugs, but the infected LS174T cells did not (P<0.01). Bystander effects of the double suicide gene system were observed in the coculture of the infected and non-infected SW480 cells. At the MOI of 100, treatment of the infected cells with the prodrugs resulted in increased cell percentage in G(0)-G(1) phase and decreased percentage in S phase and the prodrug-treated cells showed an apoptotic peak in flow cytometry.

CONCLUSIONCDglyTK fusion gene system driven by the KDR promoter selectively kills and induces the apoptosis of the KDR-CDglyTK SW480 cells.

Adenocarcinoma ; genetics ; pathology ; Adenoviridae ; genetics ; metabolism ; Apoptosis ; genetics ; Cell Line, Tumor ; Colonic Neoplasms ; genetics ; pathology ; Cytosine Deaminase ; biosynthesis ; genetics ; Genes, Transgenic, Suicide ; genetics ; Genetic Therapy ; Genetic Vectors ; genetics ; Humans ; Promoter Regions, Genetic ; genetics ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; Thymidine Kinase ; biosynthesis ; genetics ; Vascular Endothelial Growth Factor Receptor-2 ; genetics ; metabolism