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

OBJECTIVETo elucidate the killing activity of yeast cytosine deaminase/5-fluorocytosine (YCD/5-FC) gene therapy system on gene-transferred tumorigenic cell line K562B in vivo.

METHODK562B cell was infected with high titer virus and a gene transferred cell clone, YCD-K562B, was selected. Twelve male SCID mice of 4 week old were divided into 2 groups at random and both YCD-K562B and K562B cells were implanted to each mice. 5-FC or saline was given i. p for 10 days after tumor developed, and relative tumor volume was measured every 3 days. At the end of experiment, animals were sacrificed and the specimens were processed for histopathological examination.

RESULTSAt the end of experiment (21 days after tumor cell implantation), the relative tumor volume of the 4 groups were: YCD-K562B + 5-FC 2.922 +/- 0.581, YCD-K562B + saline 24.434 +/- 4.790, K562B + 5-FC 22.701 +/- 2.350 and K562B + saline 24.460 +/- 1.670; t-test analysis showed that 5-FC could kill cells (YCD-K562B) in vivo (P = 0.0001), but had no effect on the growth of gene-untransferred cells (K562B) (P = 0.096). In YCD-K562B + 5-FC group, relative tumor volume reduced in 3 approximately 6 days after treatment (the minimum was 0.681). Necrosis around artery could be found in the tumor of YCD-K562B + 5-FC group.

CONCLUSIONYCD/5-FC suicide gene therapy system has a significant in vivo killing activity to gene-transferred tumorigenic YCD-K562B cell.

Animals ; Cytosine Deaminase ; Flucytosine ; metabolism ; pharmacology ; Genetic Therapy ; methods ; Humans ; K562 Cells ; Male ; Mice ; Mice, SCID ; Neoplasm Transplantation ; Neoplasms, Experimental ; genetics ; therapy ; Nucleoside Deaminases ; genetics ; metabolism ; Saccharomyces cerevisiae ; enzymology ; Transfection ; Treatment Outcome ; Xenograft Model Antitumor Assays

Enzyme/prodrug approach is one of the actively developing areas for cancer therapy. In an effort to develop more effective enzyme/prodrug systems, cell-permeable cytosine deaminase was produced by fusing yeast cytosine deaminase (yCD) in frame with RKKRRQRRR domain of HIV-1 Tat which is an efficient delivery peptide of the foreign proteins into cells. The purified Tat-yCD fusion protein expressed in Escherichia coli was readily transduced into mammalian cells in a time- and dose-dependent manner. A significant level of the transduced Tat-yCD protein was recovered in the cell and was stable for 24 h as indicated by both results of the enzymatic assay of 5-fluorocytosine (5-FC) conversion to 5-fluorouracil (5-FU) and Western blot analysis. The cells transduced with Tat-yCD become highly sensitive to the cytotoxicity of 5-FC, while cells treated with yCD are unaffected by 5-FC. In addition, a strong bystander effect was observed with conditioned media from cells transduced with Tat-yCD added to non-transduced cells. Tat-yCD fusion protein demonstrated here for its ability to transduce into cells and convert nontoxic prodrug 5-FC to the toxic antimetabolite 5-FU, may be a useful approach for cancer therapy.
Animals ; Antimetabolites/*metabolism/pharmacology ; Bystander Effect ; Cytosine Deaminase/genetics/*metabolism ; Flucytosine/*metabolism/pharmacology ; Gene Products, tat/chemistry/genetics/*metabolism ; Genetic Vectors/genetics/metabolism ; HIV-1/metabolism ; Hela Cells/drug effects/physiology ; Humans ; Prodrugs/metabolism/therapeutic use ; Recombinant Fusion Proteins/genetics/*metabolism ; Research Support, Non-U.S. Gov't ; Saccharomyces cerevisiae Proteins/genetics/*metabolism ; *Transduction, Genetic

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

OBJECTIVE: To construct hypoxia/radiation inducible promotor HRE1.Egr-1, and to observe its promotive effect on the expression of yCDglyTK gene in nasopharyngeal cancer HNE-1 cells and the anti-tumor effect of yCDglyTK and to lay an experimental foundation for further exploration of new gene-radio therapy of nasopharyngeal cancer. METHODS: pcDNA3.1(-)HRE1.Egr-1.yCDglyTK was constructed by gene recombination technique. Stable yCDglyTK-expressing HNE-1 cells were generated by transfecting the recombinant plasmid into the target cells with liposome. The expression of yCDglyTK was detected by Western blot in 4 groups: a normoxia group, a radiation group, a hypoxia group, and a hypoxia and radiation group. The killing effect of 5-FC in different circumstances was determined by MTT. RESULTS: The expression of yCDglyTK/5-FC gene in all the groups was significantly different(P<0.01),especially in the hypoxia and radiation group. The killing effect of 5-FC on HNE1 cells varied under different conditions, especially in the hypoxia and radiation group. CONCLUSION Hypoxia and radiation can induce the activity of fusion promoter HRE1.Egr-1, and obviously promote the anti-tumor effect of yCDglyTK/5-FC system, suggesting that yCDglyTK may be a candidate suicide gene for gene-radio therapy of NPC.
Early Growth Response Protein 1 ; genetics ; Flucytosine ; pharmacology ; Gene Fusion ; physiology ; Genetic Therapy ; methods ; Humans ; Hypoxia-Inducible Factor 1, alpha Subunit ; genetics ; Nasopharyngeal Neoplasms ; genetics ; radiotherapy ; therapy ; Response Elements ; genetics ; Thymidine Kinase ; genetics ; metabolism ; Tumor Cells, Cultured

OBJECTIVETo investigate the selective killing of colorectal tumor cells by lentivirus-mediated double suicide gene under the regulation of KDR promoter.

METHODS293T packaging cells were transfected with the plasmid FGW-KDRP-CD/TK to obtain the infectious viruses. KDR-expressing LoVo cells and LS174T cells that did not produce KDR were transfected with the recombinant virus, and the transfection efficiency was evaluated by the fluorecence microscope. RT-PCR was employed to examine the expression of CDglyTK. After treatment of the cells with 5-FC and GCV, the killing effects on the two cell lines were evaluated.

RESULTSThe recombinant construct showed similar infection rate of the two cell lines. RT-PCR demonstrated that CDglyTK gene was expressed only in LoVo cells infected with FGW-KDRP-CD/TK but not in LS147T cells, and the sensitivity of the two cell lines to the prodrugs was significantly different (P<0.001). The killing effect of the double suicide gene was much stronger than that of single suicide gene administered (P<0.001).

CONCLUSIONThe double suicide gene driven by KDR promoter has specific killing effect on the KDR-expressing colorectal tumor cells.

Antimetabolites ; pharmacology ; Apoptosis ; drug effects ; Cell Line ; Cell Line, Tumor ; Colorectal Neoplasms ; genetics ; metabolism ; pathology ; Cytosine Deaminase ; genetics ; metabolism ; Flow Cytometry ; Flucytosine ; pharmacology ; Ganciclovir ; pharmacology ; Genes, Transgenic, Suicide ; genetics ; Genetic Vectors ; genetics ; Humans ; Lentivirus ; genetics ; Promoter Regions, Genetic ; genetics ; Recombinant Fusion Proteins ; genetics ; metabolism ; Thymidine Kinase ; genetics ; metabolism ; Transfection ; Vascular Endothelial Growth Factor Receptor-2 ; genetics

OBJECTIVETo study the effect of the adenovirus containing CD/TK fusion gene controlled by the human vascular endothelial growth factor (VEGF) promoter on apoptosis of human gastric carcinoma cells SGC-7901.

METHODSVEGF-expressing SGC-7901 cells were infected by the recombinant adenovirus Ad-VEGFP-CD/TK, and the infection efficiencies were observed with fluorescence microscopy. The toxic effect and intracellular calcium concentration induced by 5-fluorocytosine (5-FC) and ganciclovic (GCV) were determined by light microscopy, electron microscopy and flow cytometry.

RESULTSThe transfection efficiency of the recombinant adenovirus in SGC-7901 cells increased with the viral titer. At the multiplicity of infection (MOI) of 100, 5-FC and GCV could induce apoptosis of SGC-7901 cells within a given dose range in a dose- and time-dependent manner, and apoptotic changes of the cells were observed with electron microscopy. Apoptotic peak was also detected by flow cytometry. Cell cycle analysis revealed increased cell percentage in G(0)-G(1) phase and decreased percentage of cells in G(2)-M and S phases in response to treatment with the pro-drugs, which also induced marked elevation of intracellular calcium concentration in the infected cells.

CONCLUSIONSCD/TK fusion gene system driven by VECF promoter selectively induces apoptosis of VEGF-expressing SGC-7901 cells, the action of which is probably mediated by intracellular calcium variation.

Adenoviridae ; genetics ; physiology ; Animals ; Apoptosis ; drug effects ; genetics ; Calcium ; metabolism ; Cell Line, Tumor ; DNA ; metabolism ; DNA, Recombinant ; genetics ; Dose-Response Relationship, Drug ; Flucytosine ; pharmacology ; Ganciclovir ; pharmacology ; Genes, Transgenic, Suicide ; genetics ; Humans ; Microscopy, Electron ; Promoter Regions, Genetic ; genetics ; Stomach Neoplasms ; genetics ; metabolism ; pathology ; virology ; Vascular Endothelial Growth Factor A ; genetics

OBJECTIVETo evaluate the feasibility and efficacy of cytocine deaminase-thymidine kinase (CD-TK) fusion double suicide gene therapy using adenovirus mediated CD-TK gene and green fluorescent rotein (GFP) gene combined with ganciclovir(GCV) or 5-flourocytosine(5-FC) in a murine subcutaneous bladder carcinoma model.

METHODSA replication defective adenovirus vector containing CD-TK gene was used. Subcutaneous tumors were established in syngenic C57BL/6 female mice with 1 x 10(6) Mb49 cells. Intratumoral injection of AdCD-TK (1.58 x 10(8) PFU, qd x days) in combination with GCV (40 mg.kg(-1).d(-1), ip, qd x 10 days) or 5-FC (400 mg.kg(-1).d(-1), ip, qd x 10 days) was administered in vivo for the determination of treatment efficacy in separate controlled experiments.

RESULTSIn vivo experiments demonstrated that the mean volume of tumor in the group of AdCD-TK/GCV(326.58+/-109.56 mm(3)), AdCD-TK/5-FC (235.33+/-62.94 mm(3)) and AdCD-TK/(GCV+5-FC) (23.58+/-6.78 mm(3)) was reduced significantly compared with that of control group (993.51+/-158.32 mm(3)) (P=0.00), the mean volume of tumor in the group of AdCD-TK/(GCV+5-FC) was significantly less than that in the group of AdCD-TK/GCV or AdCD-TK/5-FC (P=0.04). Tumor necrosis was revealed by histomorphology compared with control animals.

CONCLUSIONSAdenovirus mediated CD-TK double suicide gene combining with GCV or 5-FC could provide an effective therapy in an experimental murine bladder carcinoma by significantly inhibiting tumor growth. The treatment efficacy of AdCD-TK combining GCV and 5-FC was superior to that of AdCD-TK combining GCV or AdCD-TK combining 5-FC.

Adenoviridae ; genetics ; Animals ; Cell Line ; Cell Line, Tumor ; Cytosine Deaminase ; genetics ; metabolism ; Defective Viruses ; genetics ; Female ; Flucytosine ; pharmacology ; therapeutic use ; Ganciclovir ; pharmacology ; therapeutic use ; Genes, Transgenic, Suicide ; genetics ; Genetic Therapy ; methods ; Genetic Vectors ; Mice ; Mice, Inbred C57BL ; Neoplasm Transplantation ; Thymidine Kinase ; genetics ; metabolism ; Treatment Outcome ; Urinary Bladder Neoplasms ; pathology ; therapy

OBJECTIVETo evaluate the effect of adenovirus-mediated double suicide gene (CD/TK) for selective killing of breast cancer cells.

METHODSVascular endothelial growth factor (VEGF)-expressing MCF-7 cells and normal human mammary epithelial cells that did not express VEGF were infected with the adenovirus containing VEGFP-CD/TK-GFP genes. CD/TK gene expression in the infected cells was detected by RT-PCR. After treatment of the infected cells with GCV and/or 5-FC, the cell growth status was evaluated using MTT assay, and the cell cycle changes were detected with flow cytometry. In nude mice bearing human breast cancer, the recombinant adenovirus vector was injected directly into the tumor followed by intraperitoneal injection of the prodrugs GCV and/or 5-FC, and the subsequent tumor growth was observed.

RESULTSThe recombinant adenovirus achieved similar infection rates in MCF-7 and human mammary epithelial cells, and the rates increased gradually with the multiplicity of infection (MOI) of the virus. RT-PCR demonstrated the presence of CD/TK gene product in infected MCF-7 cells, but not in the infected mammary epithelial cells. The infected MCF-7 cells, but not the mammary epithelial cells, were highly sensitive to the pro-drugs. The CD/TK fusion gene system showed significantly greater efficiency than either of the single suicide gene in killing the target cells (P<0.01). At the MOI of 100, treatment of the infected cells with the pro-drugs resulted in increased cell percentage in G(0)-G(1) phase and decreased percentage in S phase. In nude mice bearing MCF-7 cell-derived subcutaneous tumor, treatment with the double suicide gene system significantly inhibited the tumor growth, showing much stronger effect than either of the single suicide gene (P<0.01).

CONCLUSIONThe adenovirus-mediated CD/TK double suicide gene driven by VEGF promoter combined with GCV and 5-FC treatment can be an effective therapy against experimental breast cancer, and produces much greater efficacy than the single suicide gene CD/TK combined with GCV or 5-FC.

Adenoviridae ; genetics ; Breast Neoplasms ; genetics ; metabolism ; pathology ; Cell Cycle ; drug effects ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Cell Survival ; drug effects ; Cytosine Deaminase ; genetics ; metabolism ; Female ; Flow Cytometry ; Flucytosine ; pharmacology ; Ganciclovir ; pharmacology ; Genes, Transgenic, Suicide ; genetics ; Genetic Therapy ; methods ; Genetic Vectors ; genetics ; Green Fluorescent Proteins ; genetics ; metabolism ; Humans ; Recombinant Fusion Proteins ; genetics ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; Thymidine Kinase ; genetics ; metabolism ; Vascular Endothelial Growth Factor A ; genetics ; metabolism

OBJECTIVETo study the effect of adenovirus (Ad)-mediated fusion gene system driven by KDR promoter on the proliferation of human stomach adneocarcinoma SCG7901.

METHODSThe KDR-expressing SCG7901 cells and HepG2 cells that did not express KDR were both transfected with AdEasy-KDR-CDglyTK followed by treatment with the prodrugs 5-FC and/or GCV at different concentrations. The killing effects of the transfection on the cells were evaluated.

RESULTSThe expression of green fluorescent protein (GFP) was observed in 95% of the infected SCG7901 and HepG2 cells with the multiple of infection (MOI) of the Ads of 100. Transfection of SCG7901 and HepG2 cells did not produce significant changes in the cell growth, and the infected cells exhibited different sensitivities to the two prodrug: SCG7901 cells infected with rAd were highly sensitive to the prodrugs, but the infected HepG2 cells were not (P<0.01). The killing effect of CDglyTK fusion gene on the target cells was much stronger than that of either the single suicide gene (P<0.01).

CONCLUSIONCDglyTK fusion gene system driven by KDR promoter selectively kills the KDR-CDglyTK SCG7901 cells and inhibits their proliferation.

Adenocarcinoma ; genetics ; metabolism ; pathology ; Adenoviridae ; genetics ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Cell Survival ; drug effects ; Dose-Response Relationship, Drug ; Flucytosine ; pharmacology ; Ganciclovir ; pharmacology ; Genes, Transgenic, Suicide ; genetics ; Genetic Vectors ; Green Fluorescent Proteins ; biosynthesis ; genetics ; Humans ; Neovascularization, Pathologic ; genetics ; metabolism ; pathology ; Prodrugs ; pharmacology ; RNA, Messenger ; genetics ; metabolism ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; Reverse Transcriptase Polymerase Chain Reaction ; Stomach Neoplasms ; genetics ; metabolism ; pathology ; Transfection ; Vascular Endothelial Growth Factor Receptor-2 ; biosynthesis ; genetics