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PubMed2002

Differential cytotoxicity and bystander effect of the rabbit cytochrome P450 4B1 enzyme gene by two different prodrugs: implications for pharmacogene therapy.

The time course of cytotoxicity induction and the bystander effect of the rabbit cytochrome P450 4B1 (cyp4B1)/4-ipomeanol (4-IM) or 2-aminoanthracene (2-AA) pharmacogene therapy systems were investigated and compared with the herpes simplex virus type 1 thymidine kinase/ganciclovir (HSV-tk/GCV) system. Experiments were performed in rat 9L gliosarcoma cells stably expressing cyp4B1 (9L-4B1), HSV-tk (9L-tk), or their egfp (enhanced green fluorescent protein) fusion genes. Cyp4B1-mediated activation of 2-AA showed a high cell killing efficiency within only 48 hours with an onset after already 15 minutes of prodrug exposure. Residual 9L-4B1 cells were mostly damaged sublethally upon 2-AA treatment showing an S phase arrest by cell cycle analysis. 4-IM treatment of 9L-4B1 cells generated an overall weaker cell killing, especially after prodrug exposure times of less than 48 hours. Residual cells surviving 4-IM treatment showed a G2/M arrest and restarted proliferation after prodrug treatment was stopped. HSV-tk/GCV pharmacogene therapy resulted in a slower cytotoxicity induction than cyp4B1/2-AA treatment with a significantly lower cell killing efficiency after 24 and 48 hours. HSV-tk/GCV-mediated cytotoxicity was widely similar to the cytotoxicity induced by cyp4B1/4-IM with the exception of a continuous 48-hour prodrug exposure where 4-IM treatment showed a significantly higher cell killing rate. Cells surviving HSV-tk/GCV suicide gene therapy were not viable and showed an S-phase arrest. Whereas HSV-tk/GCV induced a strong bystander effect, only moderate bystander cell death depending on cell-to-cell contact was demonstrated in 9L/9L-4B1 cocultures upon 2-AA treatment and was even absent with 4-IM, thereby contrasting with earlier reports. The absence of a strong bystander effect may limit, on one hand, the overall utility of the cyp4B1 systems for cancer gene therapy. On the other hand, the weak bystander effect together with the fast induction of cytotoxicity may provide marked advantages for the use of the cyp4B1 systems as biosafety enhancers for gene marking or replacement studies and donor lymphocyte infusions after allogeneic bone marrow transplantation.

Animals↗
PubMed1998

Deletion of multiple immediate-early genes from herpes simplex virus reduces cytotoxicity and permits long-term gene expression in neurons.

Herpes simplex virus type 1 (HSV-1) has many attractive features that suggest its utility for gene transfer to neurons. However, viral cytotoxicity and transient transgene expression limit practical applications even in the absence of viral replication. Mutant viruses deleted for the immediate early (IE) gene, ICP4, an essential transcriptional transactivator, are toxic to many cell types in culture in which only the remaining IE genes are expressed. In order to test directly the toxicity of other IE gene products in neurons and develop a mutant background capable of longterm transgene expression, we generated mutants deleted for multiple IE genes in various combinations and tested their relative cytotoxicity in 9L rat gliosarcoma cells, Vero monkey kidney cells, and primary rat cortical and dorsal root neurons in culture. Viral mutants deleted simultaneously for the IE genes encoding ICP4, ICP22 and ICP27 showed substantially reduced cytotoxicity compared with viruses deleted for ICP4 alone or ICP4 in combination with either ICP22, ICP27 or ICP47. Infection of neurons in culture with these triple IE deletion mutants substantially enhanced cell survival and permitted transgene expression for over 21 days. Such mutants may prove useful for efficient gene transfer and extended transgene expression in neurons in vitro and in vivo.

Animals↗
PubMed2003

Dexamethasone inhibits the anti-tumor effect of interleukin 4 on rat experimental gliomas.

Retroviral-mediated gene transfer of the IL-4 gene into experimental gliomas can cause tumor rejection, supporting the clinical use of this form of gene therapy for glioblastomas (GBM). In a clinical setting, the administration of dexamethasone (dex) is a standard procedure for GBM patients. This led us to examine the effects of dex on IL-4 gene therapy. We injected intracranially Fischer 344 rats with phosphate-buffered saline, 9L gliosarcoma cells mixed with E86.L4SN(200) cells (retroviral producer cells, RPC, transducing IL-4 cDNA) and 9L cells mixed with PA317.STK.SBA cells (control RPC expressing the HSV-tk gene). The rats from each group were treated with 0, 50, 100 or 250 microg dex/kg/day released by osmotic pumps implanted subcutaneously. While 80-100% of rats receiving 9L cells mixed with IL-4 RPC and not treated by dex survived for at least 2 months following tumor injection, only 50% and 17% of rats receiving 50 or 100 microg/kg/day of dex, respectively, reached this time point. These results indicate that dex significantly diminished the anti-tumor effect of IL-4. Thus, in a clinical setting, IL-4 gene transfer should be performed when low levels of dex are administered or in the absence of dex.

Animals↗
PubMed1999

Treatment of experimental brain tumors with trombospondin-1 derived peptides: an in vivo imaging study.

Antiangiogenic and antiproliferative effects of synthetic D-reverse peptides derived from the type 1 repeats of thrombospondin (TSP1) were studied in rodent C6 glioma and 9L gliosarcomas. To directly measure tumor size and vascular parameters, we employed in vivo magnetic resonance (MR) imaging and corroborated results by traditional morphometric tissue analysis. Rats bearing either C6 or 9L tumors were treated with TSP1-derived peptide (D-reverse amKRFKQDGGWSHWSPWSSac, n=13) or a control peptide (D-reverse amKRAKQAGGASHASPASSac, n=12) at 10 mg/kg, administered either intravenously or through subcutaneous miniosmotic pumps starting 10 days after tumor implantation. Eleven days later, the effect of peptide treatment was evaluated. TSP1 peptide-treated 9L tumors (50.7+/-44.2 mm3, n=7) and C6 tumors (41.3+/-34.2 mm3, n=6) were significantly smaller than tumors treated with control peptide (9L: 215.7+/-67.8 mm3, n=6; C6: 184.2+/-105.2 mm3, n=6). In contrast, the in vivo vascular volume fraction, the mean vascular area (determined by microscopy), and the microvascular density of tumors were not significantly different in any of the experimental groups. In cell culture, TSP1, and the amKRFKQDGGWSHWSPWSSac peptide showed antiproliferative effects against C6 with an IC of 45 nM for TSP1. These results indicate that TSP1-derived peptides retard brain tumor growth presumably as a result of slower de novo blood vessel formation and synergistic direct antiproliferative effects on tumor cells. We also show that in vivo MR imaging can be used to assess treatment efficacy of novel antiangiogenic drugs non-invasively, which has obvious implications for clinical trials.

Animals↗
PubMedDate not supplied

Rapid and quantitative assessment of cancer treatment response using in vivo bioluminescence imaging.

Current assessment of orthotopic tumor models in animals utilizes survival as the primary therapeutic end point. In vivo bioluminescence imaging (BLI) is a sensitive imaging modality that is rapid and accessible, and may comprise an ideal tool for evaluating antineoplastic therapies. Using human tumor cell lines constitutively expressing luciferase, the kinetics of tumor growth and response to therapy have been assessed in intraperitoneal, and subcutaneous, and intravascular cancer models. However, use of this approach for evaluating orthotopic tumor models has not been demonstrated. In this report, the ability of BLI to noninvasively quantitate the growth and therapeutic-induced cell kill of orthotopic rat brain tumors derived from 9L gliosarcoma cells genetically engineered to stably express firefly luciferase (9LLuc) was investigated. Intracerebral tumor burden was monitored over time by quantitation of photon emission and tumor volume using a cryogenically cooled CCD camera and magnetic resonance imaging (MRI), respectively. There was excellent correlation (r=0.91) between detected photons and tumor volume. A quantitative comparison of tumor cell kill determined from serial MRI volume measurements and BLI photon counts following 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) treatment revealed that both imaging modalities yielded statistically similar cell kill values (P=.951). These results provide direct validation of BLI imaging as a powerful and quantitative tool for the assessment of antineoplastic therapies in living animals.

Animals↗
PubMed1996

Eradication of established intracranial rat gliomas by transforming growth factor beta antisense gene therapy.

Like human gliomas, the rat 9L gliosarcoma secretes the immunosuppressive transforming growth factor beta (TGF-beta). Using the 9L model, we tested our hypothesis that genetic modification of glioma cells to block TGF-beta expression may enhance their immunogenicity and make them more suitable for active tumor immunotherapy. Subcutaneous immunizations of tumor-bearing animals with 9L cells genetically modified to inhibit TGF-beta expression with an antisense plasmid vector resulted in a significantly higher number of animals surviving for 12 weeks (11/11, 100%) compared to immunizations with control vector-modified 9L cells (2/15, 13%) or 9L cells transduced with an interleukin 2 retroviral vector (3/10, 30%) (P < 0.001 for both comparisons). Histologic evaluation of implantation sites 12 weeks after treatment revealed no evidence of residual tumor. In vitro tumor cytotoxicity assays with lymph node effector cells revealed a 3- to 4-fold increase in lytic activity for the animals immunized with TGF-beta antisense-modified tumor cells compared to immunizations with control vector or interleukin 2 gene-modified tumor cells. These results indicate that inhibition of TGF-beta expression significantly enhances tumor-cell immunogenicity and supports future clinical evaluation of TGF-beta antisense gene therapy for TGF-beta-expressing tumors.

Animals↗
PubMed2001

Gamma-glutamyl transferase expression in higher-grade astrocytic glioma.

Increased expression of gamma-glutamyltransferase (GGT) has been detected in a range of human malignancies and is thought to be involved in neoplastic proliferation and treatment resistance. Since GGT expression and its role in malignant glioma biology remain largely unknown, we investigated this phenomenon by immunostaining 26 higher-grade human astrocytic gliomas (WHO grades III and IV) with a monoclonal anti-GGT-antibody (138H11). Further, human pancreatic GGT cDNA was used for liposome-mediated transfection of 9L gliosarcoma cells. GGT-expressing and control 9L cells were cultured in media containing different amounts of essential amino acids and/or cytotoxic agents. Cell viability was evaluated by microplate MTT assay. Immunohistochemical staining of tumor specimens demonstrated that GGT expression is a frequent feature of higher-grade human astrocytic gliomas, but not of normal brain tissue. Human tumors were strongly GGT-positive in 6 of 7 cases of grade III astrocytoma, and in 12 of 19 grade IV astrocytoma (glioblastoma multiforme, GBM) cases. In the cell culture model, 9L-GGT cells had a growth advantage over control cells in cysteine-deficient medium. but not in standard or glutamine-free medium. No significant difference in numbers of viable cells of either clone was found in media containing the alkylating drug BCNU (5-200 microg/ml). In conclusion, GGT is expressed in a high percentage of human WHO grade III astrocytomas and GBM, but not in normal brain tissue. This molecule seems to give neoplastic cells a moderate growth advantage under in vivo conditions.

Adult↗
PubMed1994

Gene transfer into experimental brain tumors mediated by adenovirus, herpes simplex virus, and retrovirus vectors.

Three vectors derived from retrovirus, herpes simplex virus type 1 (HSV), and adenovirus were compared in cultured rat 9L gliosarcoma cells for gene transfer efficiency and in a 9L rat brain tumor model for histologic pattern and distribution of foreign gene delivery, as well as for associated tumor necrosis and inflammation. At a multiplicity of infection of 1, in vitro transfer of a foreign gene (lacZ from Escherichia coli) into cells was more efficient with either the replication-defective retrovirus vector or the replication-conditional thymidine kinase (TK)-deficient HSV vector than with the replication-defective adenovirus vector. In vivo, stereotactic injections of each vector into rat brain tumors revealed three main histopathologic findings: (i) retrovirus and HSV vector-mediated gene transfer was relatively selective for cells within the tumor, whereas adenovirus vector-mediated gene transfer occurred into several types of endogenous neural cells, as well as into cells within the tumor; (ii) gene transfer to multiple infiltrating tumor deposits without apparent gene transfer to intervening normal brain tissue occurred uniquely in one animal inoculated with the HSV vector, and (iii) extensive necrosis and selective inflammation in the tumor were evident with the HSV vector, whereas there was minimal evidence of tumor necrosis and inflammation with either the retrovirus or adenovirus vectors.

Adenoviruses, Human↗
PubMed1996

Evaluation of the bystander effect in experimental brain tumors bearing herpes simplex virus-thymidine kinase gene by serial magnetic resonance imaging.

Antitumor effects of herpes simplex virus-thymidine kinase (HSV-tk) gene transfer followed by ganciclovir (GCV) administration were studied by serial magnetic resonance imaging (MRI) with reference to the bystander effect. Mixed populations of 9L-gliosarcoma cells transduced with the HSV-tk gene (TK cells) and wild-type 9L cells were implanted into the brain of syngeneic Fisher rats at various ratios (total cell number, 10(5) cells; percentage of TK cells, 100%, 25%, 10%, or 0%). Rats were treated with GCV (30 mg/kg per day) or saline for 14 days and tumor masses were visually monitored using MRI. All of the saline-treated rats (regardless of TK cell percentage) and GCV-treated rats inoculated with 0% TK cells died between day 19 and day 31 (mean survival, 22.9 days) due to progressive tumor growth. The GCV-treated rats inoculated with more than 10% of TK cells lived significantly longer than the saline-treated rats (p < 0.01). The mean survivals of GCV-treated groups were 50.7, 70.0, and longer than 100 days for 10%, 25%, and 100% TK cells, respectively. MRI study revealed that reduction in tumor size and disappearance of tumor were observed in the GCV-treated rats inoculated with 10% or 25% TK cells. Complete regression of the tumor was, however, observed only in the rats implanted with 100% TK cells. The present results show that the bystander effect is clearly observed in vivo in a TK percentage-dependent manner, and a population of more than 25% of TK-positive cells is required for complete tumor elimination.

Animals↗
PubMed1996

Long-term survival in a rodent model of disseminated brain tumors by combined intrathecal delivery of herpes vectors and ganciclovir treatment.

Brain tumors that have disseminated into cerebrospinal fluid (CSF) pathways are an unresolved therapeutic problem, especially in pediatric neurooncology. Here a gene therapy approach using the herpes simplex virus type 1 thymidine kinase (HSV-TK)/ganciclovir (GCV) paradigm was tested using an HSV vector in a rodent model of disseminated central nervous system tumors. 9L-gliosarcoma cells were implanted simultaneously into the brain and the CSF of syngeneic rats. Five days later, resulting intracerebral and leptomeningeal tumors were treated by intrathecal injection of a replication-conditional HSV vector. This vector was defective for the ribonucleotide reductase gene, but contained an intact HSV-tk gene. Systemic GCV treatment was started 2 days after vector application and continued for 14 days. Tumor-free, long-term survival (LTS) was achieved in 90% of the animals treated with this combined therapeutic approach, whereas only 30% LTS was found in animals that had received the vector alone and 10% LTS in untreated animals. This therapeutic response probably involves oncolytic, on-site replication of the vector, activation of GCV by a HSV-TK, and a strong immune response both to the vector and to 9L cells. Apparent vector-related mortality was observed in 20% of animals without subsequent GCV therapy, but no vector-related mortality was found when the animals were treated with GCV after vector application. Given the successful outcome of this experimental treatment and the apparent potential of GCV to control HSV-related toxicity, intrathecal application of HSV vectors combined with GCV treatment may be a promising approach for treatment of disseminated brain tumors.

Animals↗
PubMed1996

Herpes simplex virus thymidine kinase gene therapy for rat malignant brain tumors.

Transfer of a herpes simplex virus-derived thymidine kinase (HSV-tk) gene into brain tumor cells and subsequent ganciclovir (GCV) treatment has been shown by others to be an effective treatment in rats with intracerebrally inoculated 9L gliosarcomas. Mechanism of action and reproducibility are, however, still a matter of debate. We have used the same model to test the therapeutic effects of both retrovirus- and adenovirus-mediated transfer of the HSV-tk gene followed by GCV treatment. Survival time of rats with intracerebral 9L tumors was significantly prolonged after a single administration of adenovirus carrying a HSV-tk gene as compared to controls. Retrovirus-mediated gene transfer also resulted in significantly prolonged survival time when recombinant retrovirus-producing cells were transplanted. Direct injection of the recombinant retrovirus, HSV-tk-expressing cells, virus-producing cells without GCV administration and recombinant retrovirus-lacZ or interleukin-2 (IL-2)-producing cells did not result in tumor cell kill. In the present study, no significant difference in survival of 9L brain tumor carrying rats was found after treatment with adenovirus as compared to retrovirus-mediated HSV-tk-mediated gene transfer and subsequent GCV treatment.

Adenoviruses, Human↗
PubMed1996

Herpes vector-mediated delivery of marker genes to disseminated central nervous system tumors.

The present study investigated the ability of a recombinant herpes simplex virus type 1 (HSV) vector to deliver genes into disseminated brain tumor foci through intrathecal injection of the vector. The animal model was designed to simulate brain tumors with cerebrospinal fluid (CSF) metastases, which are found especially in the pediatric population. 9L gliosarcoma cells were injected both into the right frontal lobe and in through the cisterna magna of adult rats. The HSV vector, hrR3, was inoculated intrathecally 5 days later. This vector is defective in the gene for ribonucleotide reductase, and, therefore, replicates preferentially in dividing cells; it retains an intact HSV-thymidine kinase gene (HSV-tk). Two days after injection of the vector, immunohistochemical staining for HSV thymidine kinase (HSV-TK) revealed expression in frontal tumors, as well as in leptomeningeal tumor foci along the entire neuroaxis. HSV-TK-immunopositive cells were most frequent in small tumors contacting the CSF pathways. Frontal lobe tumors showed the highest density of HSV-TK-immunopositive cells around their periphery with little expression in central parts. Some paraventricular neurons temporarily showed HSV-TK-immunolabeling at this early time point. The number of HSV-TK-immunopositive tumor cells markedly decreased 5 days after injection of the HSV vector. In all animals, some toxicity was observed in the first 2-4 days after virus injection with extensive leptomeningeal inflammation. In conclusion, intrathecal application of HSV vectors can mediate widespread transfer of the therapeutic HSV-tk gene into disseminated tumors throughout the brain and CSF pathways. Although there was marked toxicity associated with intrathecal injection of this vector, this mode of gene delivery offers a promising approach for treatment of CSF-metastases in conjunction with development of less toxic vectors.

Animals↗
PubMed1996

In vivo replication-deficient adenovirus vector-mediated transduction of the cytosine deaminase gene sensitizes glioma cells to 5-fluorocytosine.

Viral vector-mediated transfer of chemosensitization genes represents a promising new approach to the treatment of cancer. Previous reports have demonstrated that transfection of the bacterial cytosine deaminase (cd) gene into mammalian cells can sensitize them to the otherwise nontoxic nucleoside, 5-fluorocytosine (5-FC). We now report that a replication-deficient adenovirus vector that transduces the cd gene (Ad.CMV-cd) highly sensitizes 9L gliosarcoma cells to 5-FC, and that gene transduction is associated with a potent bystander effect that is not dependent on direct cell-to-cell contact. Stereotactic injection of Ad.CMV-cd into established rat gliomas, followed by systemic administration of 5-FC in vivo, results in prolongation of survival.

Adenoviruses, Human↗
PubMed1997

Glioma cells transduced with an Escherichia coli CD/HSV-1 TK fusion gene exhibit enhanced metabolic suicide and radiosensitivity.

To ascertain whether concomitant expression of Escherichia coli deaminase (CD) and herpes simplex virus type-1 thymidine kinase (HSV-1 TK) could mediate greater levels of cytotoxicity beyond that observed with either suicide gene alone, 9L gliosarcoma cells were transduced with a retrovirus encoding a CD/HSV-1 TK fusion gene. The resultant CD/HSV-1 TK fusion protein (CDglyTK) was found to be bifunctional via CD and HSV-1 TK enzymatic assays, and conferred upon cells prodrug sensitivities equivalent to or better than that observed for each enzyme independently (ganciclovir [GCV] and bromovinyldeoxyuridine [BVdU] for HSV-1 TK and 5-fluorocytosine [5-FC] for CD). Simultaneous treatment of CDglyTK-expressing cells with prodrugs specific for HSV-1 TK and CD (GCV/5-FC or BVdU/5-FC) resulted in slight synergistic toxicity, two- to three-fold greater than that expected if the cytotoxic effects of each prodrug were purely additive. More importantly, co-treatment with HSV-1 TK- and CD-specific prodrugs was found to increase greatly the radiosensitivity of CDglyTK-expressing cells. Sensitivity enhancement ratios of 2.44 (GCV/5-FC) and 3.90 (BVdU/5-FC) were achieved. The results suggest that double suicide gene therapy, using a bifunctional CD/HSV-1 TK fusion gene, coupled with radiotherapy may provide a highly efficient means of selectively treating cancer.

Blotting, Western↗
PubMed1998

Bystander effect-mediated therapy of experimental brain tumor by genetically engineered tumor cells.

Transfer of the herpes simplex virus-thymidine kinase (HSV-tk) gene, followed by administration of ganciclovir (GCV), generates the "bystander effect," in which HSV-tk-negative wild-type cells, as well as HSV-tk-expressing cells, are killed by GCV. To eradicate an intracranial tumor by this bystander effect, we injected the tumor cells transduced with the HSV-tk gene (TK cells) in the vicinity of the preimplanted wild-type tumor and then administered GCV. Wild-type 9L-gliosarcoma cells (1 x 10[5]) were implanted into the brain of syngeneic Fisher rats. On the next day, rats were injected with TK cells (1 x 10(5) or 3 x 10[5]) or medium alone at the same brain coordinate and then treated with GCV or saline. Administration of GCV significantly prolonged the survival of the rats injected with TK cells compared with that injected with medium alone (p < 0.01). Reduction in tumor size and retardation of tumor growth were observed by serial magnetic resonance imaging in the rats that received the combination of TK cells and GCV. The results show that the bystander effect is also achieved in vivo even when TK cells and wild-type cells are not simultaneously implanted. This treatment modality circumvents potential risks accompanied with in vivo gene transfer. Because there remained substantially no HSV-tk-positive cells in the recurrent tumors, this modality offers a "safe" therapeutic strategy against human malignant gliomas.

Animals↗
PubMed1998

Transgene expression in malignant glioma using a replication-defective adenoviral vector containing the Egr-1 promoter: activation by ionizing radiation or uptake of radioactive iododeoxyuridine.

One approach to improving the specificity of gene therapy involves using radiosensitive promoters to activate gene expression selectively in the radiation field. In this study, we evaluated the ability of irradiation to regulate the transcription of a recombinant replication-defective adenovirus vector, Ad.Egr-1/lacZ, containing the radiation-inducible Egr-1 promoter driving the beta-galactosidase reporter gene in glioma cells. Transcripts of the Egr-1 gene in human and rat glioma cells were induced following irradiation with as little as 2 Gy. This dose was 10-fold less than previously reported, and comparable to doses of irradiation used clinically in standard fractionated radiotherapy for brain tumors. When 9L rat gliosarcoma cells were infected with Ad.Egr-1/lacZ in vitro and exposed to 2 Gy of external beam irradiation, there was a threefold increase in beta-galactosidase expression. Irradiation of intracerebral 9L tumors infected with the Ad.Egr-1/lacZ virus, using either external beam radiotherapy (2 Gy) or the thymidine analog 5-iodo-2'-deoxyuridine radiolabeled with the Auger electron emitter iodine-125 ([125I]IdUrd), also resulted in increased beta-galactosidase activity of the tumor cells. These results indicate that the use of viral vectors containing radiation-inducible promoters represents a novel therapeutic approach that enables gene therapy to be spatially and temporally regulated by ionizing radiation. These findings also support a potential role for radiation-inducible promoters in the treatment of malignant brain tumors.

Animals↗
PubMed2000

Characterization of a canine glioma cell line as related to established experimental brain tumor models.

A large animal tumor model for anaplastic glioma has been recently developed using immunotolerant allogeneic Beagle dogs and an established canine glioma cell line, J3T. This model offers advantages in terms of tumor morphology and similarity to human anaplastic glioma. The present study was aimed at evaluating the biological characteristics of the J3T canine glioma cell line as related to experimental gene therapy studies. Furthermore, development and morphology of canine brain tumors in a xenogeneic immunodeficient SCID mouse model was investigated. It was demonstrated that cultured J3T cells can be efficiently infected by adenovirus (AV), herpes-simplex type I (HSV), or retrovirus (RV) vectors, as well as by non-virus vectors such as cationic liposome/DNA complexes. Thus, in terms of infectability and transfectability, J3T cells seem to be closer to human glioma than the 9L rodent gliosarcoma. Cytotoxicity of selection antibiotics such as G418, puromycin, and hygromycin on J3T cells essentially resemble cytotoxicity seen with other established glioma lines, for example, 9L, U87, or U343. RV-mediated HSV-TK/GCV gene therapy demonstrated comparable LD50 for TK-expressing and control (non-expressing) J3T and 9L cells treated with Ganciclovir. Further, it was proven that J3T cells are tumorigenic and may grow heterotopically and orthotopically in a xenogeneic immunodeficient host, the SCID mouse, although morphology and growth pattern of these xenogeneic tumors differ from the demonstrated invasive phenotype in the Beagle dog.

3T3 Cells↗
PubMed1997

Prediction of drug cytotoxicity in 9L rat brain tumor by using flow cytometry with a deoxyribonucleic acid-binding dye.

OBJECTIVE: Flow cytometry (FCM) with a deoxyribonucleic acid (DNA)-binding dye, propidium iodide, provides a rapid and quantitative method to detect apoptotic cell death. This technique was used to examine the sensitivity of tumor cells to anticancer agents, as a novel test of chemosensitivity in vitro. METHODS: The in vitro chemosensitivity of 9L gliosarcoma cells to a panel of anticancer agents (cisplatin, nimustine, adriamycin, cyclophosphamide, vincristine, 5-fluorouracil, and methotrexate) was investigated by both FCM, yielding DNA histograms, and a microtiter tetrazolium test, measuring cellular metabolism. Clinically achievable concentrations of the agents were used for the analysis of DNA histograms and proliferation of 9L cells in vitro. Rats intracranially inoculated with 9L cells were treated with the agents, and tumor masses were visually monitored by using magnetic resonance imaging with gadolinium-diethylenetriaminepentaacetic acid enhancement. RESULTS: The cytotoxic effect of anticancer agents examined by the microtiter tetrazolium test correlated with a decreased G0/G1 peak in the DNA histograms. Serial FCM analysis showed that the decrease in the G0/G1 peak was subsequently accompanied by increased hypodiploid areas, suggesting DNA fragmentation induced by the agents. The in vitro chemosensitivity test and cell proliferation examination showed that all agents except cisplatin were effective. Growth retardation of inoculated brain tumors and prolonged survival of inoculated rats were observed with treatment with the anticancer agents, except cisplatin. CONCLUSION: The present study shows that FCM analysis with a DNA-binding dye can detect DNA damage induced by anticancer agents, and it suggests that this technique is a novel method to test chemosensitivity in vitro.

Animals↗