PURPOSE: Among cancer gene therapies, the aims to eliminate malignant cells using genes as drugs as substitutes for conventional therapy, the use of bacterial cytosine deaminase (CD) which can convert the nontoxic 5-fluorocytosine (5-FC) to toxic 5-fluorouracil (5-FU), has been reported to provide a useful system for the selective killing of gene- modified mammalian tumor cells. Recently the transfection and expression of the CD gene, and the toxicity of 5-FC in eukaryotic cells, have been reported in colon, prostate and breast cancers, as well as in glioblastomas. To evaluate the growth inhibition effects in WiDr and LoVo colorectal cancer cells, after CD gene transfection and 5-FC administration, for the selective killing of cancer cells. METHODS: WiDr and LoVo colon cancer cell lines were cultured and the absorbencies for the percentage survival, on days 2, 4, 6, 8, and 10 of the culture, estimated by the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetra-zolium bromide (MTT) test. The experimental subjects were divided as follows; Group 1: administration of 5-FC only, Group 2: administration of 5-FU only, Group 3: administration of 5-FC after CD gene transfection using pCMV/CD-1 plasmid vector. Each experiment, on days 2, 4, 6, 8 and 10 of the culture after the administration of 5-FC or 5-FU concentration of 10, 100 and 1000 uM, was triplicated and calculated the mean with standard deviation. The bacterial CD gene was transfected into each cell lines, using the lipofectin method, and the transfection and expression of the CD protein identified with beta-galactosidase immunohistochemical staining and western blotting. The growth inhibition effects in group 3 were compared with those in group 1 and 2, and the bystander effects and cell recoveries, after finishing the 5-FC treatment, evaluated until day 20 of the culture. RESULTS: The calculated survival percentages by from the MTT tests in the WiDr and LoVo cells revealed 110~150% enhancing effects after the administration of 5-FC concentration of 10, 100 and 1000micro M (group 1), and 30~90% after the administration of 5-FU at the same concentrations (group 2), which were shown to be statistically significantly (P<0.001). After transfection of pCMV/CD-1 plasmid vector into the WiDr and LoVo cells using the lipofectin method, the transfection rate of the WiDr and LoVo cells were 4.2 +/- 0.6% and 13.8 +/- 0.8%, respectively. Also the CD protein, with the polyclonal anti-CD antibody, by western blot, revealed weak expression on day 2, followed by strong expression on day 4, which progressively decreased by days 6 and 8 in the WiDr cells. Conversely, the LoVo cells showed weak expression on day 2, which progressively increased by days 4 and 6, was followed by the strongest expression on day 8 in LoVo cells. About 60~85% significant growth inhibition effects (P<0.001) were revealed in group 3, with proportionally different effects, corresponding to the CD gene transfection rate, concentration of 5-FC and duration of the culture. The 60~85% growth inhibition effects were complex of the response to the transfection rate and the bystander effects of CD expressed cells to the CD non-expressed cells. CONCLUSION: From our results, the administration of 5-FC after CD gene transfection revealed statistically significant growth inhibition effects of 60~85%, which were complex of the effects of CD expressed cells and the bystander effects to the CD non-expressed cells, and proportionally corresponding to the transfection rate, the duration of the CD protein expression and the concentration of 5-FC.
beta-Galactosidase ; Blotting, Western ; Breast ; Bystander Effect ; Cell Line* ; Colon* ; Colonic Neoplasms* ; Colorectal Neoplasms ; Cytosine Deaminase* ; Cytosine* ; Eukaryotic Cells ; Flucytosine* ; Fluorouracil ; Genes, Neoplasm ; Glioblastoma ; Homicide* ; Plasmids ; Prostate ; Transfection*

PURPOSE: Among cancer gene therapies, the aims to eliminate malignant cells using genes as drugs as substitutes for conventional therapy, the use of bacterial cytosine deaminase (CD) which can convert the nontoxic 5-fluorocytosine (5-FC) to toxic 5-fluorouracil (5-FU), has been reported to provide a useful system for the selective killing of gene- modified mammalian tumor cells. Recently the transfection and expression of the CD gene, and the toxicity of 5-FC in eukaryotic cells, have been reported in colon, prostate and breast cancers, as well as in glioblastomas. To evaluate the growth inhibition effects in WiDr and LoVo colorectal cancer cells, after CD gene transfection and 5-FC administration, for the selective killing of cancer cells. METHODS: WiDr and LoVo colon cancer cell lines were cultured and the absorbencies for the percentage survival, on days 2, 4, 6, 8, and 10 of the culture, estimated by the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetra-zolium bromide (MTT) test. The experimental subjects were divided as follows; Group 1: administration of 5-FC only, Group 2: administration of 5-FU only, Group 3: administration of 5-FC after CD gene transfection using pCMV/CD-1 plasmid vector. Each experiment, on days 2, 4, 6, 8 and 10 of the culture after the administration of 5-FC or 5-FU concentration of 10, 100 and 1000 uM, was triplicated and calculated the mean with standard deviation. The bacterial CD gene was transfected into each cell lines, using the lipofectin method, and the transfection and expression of the CD protein identified with beta-galactosidase immunohistochemical staining and western blotting. The growth inhibition effects in group 3 were compared with those in group 1 and 2, and the bystander effects and cell recoveries, after finishing the 5-FC treatment, evaluated until day 20 of the culture. RESULTS: The calculated survival percentages by from the MTT tests in the WiDr and LoVo cells revealed 110~150% enhancing effects after the administration of 5-FC concentration of 10, 100 and 1000micro M (group 1), and 30~90% after the administration of 5-FU at the same concentrations (group 2), which were shown to be statistically significantly (P<0.001). After transfection of pCMV/CD-1 plasmid vector into the WiDr and LoVo cells using the lipofectin method, the transfection rate of the WiDr and LoVo cells were 4.2 +/- 0.6% and 13.8 +/- 0.8%, respectively. Also the CD protein, with the polyclonal anti-CD antibody, by western blot, revealed weak expression on day 2, followed by strong expression on day 4, which progressively decreased by days 6 and 8 in the WiDr cells. Conversely, the LoVo cells showed weak expression on day 2, which progressively increased by days 4 and 6, was followed by the strongest expression on day 8 in LoVo cells. About 60~85% significant growth inhibition effects (P<0.001) were revealed in group 3, with proportionally different effects, corresponding to the CD gene transfection rate, concentration of 5-FC and duration of the culture. The 60~85% growth inhibition effects were complex of the response to the transfection rate and the bystander effects of CD expressed cells to the CD non-expressed cells. CONCLUSION: From our results, the administration of 5-FC after CD gene transfection revealed statistically significant growth inhibition effects of 60~85%, which were complex of the effects of CD expressed cells and the bystander effects to the CD non-expressed cells, and proportionally corresponding to the transfection rate, the duration of the CD protein expression and the concentration of 5-FC.
beta-Galactosidase ; Blotting, Western ; Breast ; Bystander Effect ; Cell Line* ; Colon* ; Colonic Neoplasms* ; Colorectal Neoplasms ; Cytosine Deaminase* ; Cytosine* ; Eukaryotic Cells ; Flucytosine* ; Fluorouracil ; Genes, Neoplasm ; Glioblastoma ; Homicide* ; Plasmids ; Prostate ; Transfection*

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: The poor prognosis of advanced bladder cancer requires the investigation of novel treatment modalities. In this study, we investigated the suicide gene therapy for bladder cancer, using the adenovirus-mediated expression of Escherichia coli cytosine deaminase (CD) in conjunction with the prodrug 5-fluorocytosine (5-FC). MATERIALS AND METHODS: A replication-deficient recombinant adenovirus, which contains the Rous sarcoma virus (RSV) promoter driving the expression of CD, (Ad-RSV-CD) was constructed. In vitro cell-killing assay, using Ad-RSV-CD (20 MOI) plus 5-FC (500muM), was performed in bladder cancer cell lines, HT-1376, UM-UC-3 and NBT-II. The CD enzymatic activity was measured in the Ad-RSV-CD (20 MOI) infected cells, and the concentrations of 5-fluorouracil (5-FU) yielding an IC50 were calculated for those cells. RESULTS: 5-FU dose response curve showed that IC50 of NBT-II was 0.8muM, HT-1376 1.0muM and UM-UC-3 5.1muM at day 6. The CD enzymatic activities of the Ad-RSV-CD infected UM-UC-3, HT-1376 and NBT-II cells were 5696, 4655, 1766 pmole/1x10(6) cells, respectively. Whereas the administration of 5-FC (500muM) or Ad-RSV-CD (20 MOI) alone demonstrated no cytotoxicity to cells, Ad-RSV-CD/5-FC exhibited a significant cytotoxic effect in the cells, especially the UM-UC-3 and HT-1376. CONCLUSIONS: Ad-RSV-CD/5-FC suicide gene therapy is effective for bladder cancer cells in cell cultures, suggesting this approach may have potential as a strategy for the treatment of bladder cancer.
Adenoviridae* ; Cell Culture Techniques ; Cell Line ; Cytosine Deaminase* ; Cytosine* ; Escherichia coli* ; Escherichia* ; Flucytosine ; Fluorouracil ; Genetic Therapy* ; Inhibitory Concentration 50 ; Prognosis ; Rous sarcoma virus ; Suicide* ; Urinary Bladder Neoplasms* ; Urinary Bladder*

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

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

No abstract available.
Child, Preschool ; Cryptococcosis/drug therapy* ; Cytosine/analogs & derivatives* ; Female ; Flucytosine/therapeutic use* ; Human

OBJECTIVETo investigate whether hyperthermia can enhance the killing effect of 5- fluorocytosine (5- FC) on human colorectal carcinoma cell lines SW480 transfected with carcinoembryonic antigen (CEA) tissue- specific cytosine deaminase (CD) gene in vitro,and study its mechanism.

METHODSHuman colorectal carcinoma cell lines SW480 transfected with G1CEACDNa were cultured. The proliferated colonies were treated with the combined therapy of 5-FC and hyperthermia at a temperature of 43 degrees C for 30 min. After eight days, MTT was used to calculate the cellular survival rate,to analyze the killing effect of 5-FC combined with hyperthermia on SW480 cells transfected with CD gene. Flow cytometry was performed to analyze the cellular cycle and transmission electron microscope was used to observe the morphologic changes of SW480 cells after thermochemotherapy.

RESULTSHyperthermia combined with 5-FC had an enhanced killing effect on SW480-CEACD cells than 5-FC alone (P< 0.05, t =2.403, n=9). Flow cytometry revealed that the proportion of S stage cell increased in the group treated with hyperthermia and 5- FC (P< 0.001, t =7.158, n=6). Transmission electron microscope showed apoptosis after thermo- chemotherapy.

CONCLUSIONSHyperthermia can improve the anti- tumor effect of 5- FC on human colorectal carcinoma cell lines SW480 transfected with CD gene, and the cells were blocked at S stage of cellular cycle and apoptosis was induced following thermochemotherapy.

Cell Line, Tumor ; Cytosine Deaminase ; genetics ; Flucytosine ; pharmacology ; Genes, Transgenic, Suicide ; Genetic Therapy ; methods ; Hot Temperature ; Humans

Diazepam is known to have cardiovascular depressive effects through a combined action on benzodiazepinergic receptor and the GABA receptor-chloride ion channel complex. Moreover, it is known that barbiturates also have some cardiovascular regulatory effects mediated by the central GABAergic system. Therefore, this study was undertaken to delineate the regulatory actions and interactions of these systems by measuring the responses of the cardiovascular system and renal nerve activity to muscimol, diazepam and pentobarbital, administered intracerebroventricularly in rabbits. When muscimol (0.03~-0.3 microgram/kg), diazepam (10~100 microgram/kg) and pentobarbital (1-10 microgram/kg) were injected into the lateral ventricle of the rabbit brain, there were similar dose-dependent decreases in blood pressure (BP) and renal nerve activity (RNA). The relative potency of the three drugs in decreasing BP and RNA was muscimol > pentobarbital >diazepam. Muscimol and pentobarbital also decreased the heart rate in a dose-dependent manner; however, diazepam produced a trivial, dose-independent decrease in heart rate. Diazepam (30 microgram/kg) pentobarbital (3 microgram/kg) did not. Bicuculline (0.5 microgram/kg), a GABAergic receptor blocker, significantly augmented the effect of muscimol (0.1 microgram/kg) in decreasing blood pressure and renal nerve activity, but of pentobarbital in decreasing BP and RNA, either alone or with muscimol. We inferred that the central benzodiazepinergic and barbiturate systems help regulate peripheral cardiovascular function by modulating the GABAergic system, which adjusts the output of the vasomotor center and hence controls peripheral sympathetic tone. Benzodiazepines more readily modulate the GABAergic system than barbiturates.
Barbiturates ; Benzodiazepines ; Bicuculline ; Blood Pressure ; Brain ; Cardiovascular System ; Diazepam ; gamma-Aminobutyric Acid ; Heart Rate ; Ion Channels ; Lateral Ventricles ; Muscimol ; Pentobarbital ; Rabbits ; RNA