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At least 487 records · Page 27Linked to original sources
PubMed2005

Grafts of brain-derived neurotrophic factor and neurotrophin 3-transduced primate Schwann cells lead to functional recovery of the demyelinated mouse spinal cord.

Experimental studies provided overwhelming proof that transplants of myelin-forming cells achieve efficient remyelination in the CNS. Among cellular candidates, Schwann cells can be used for autologous transplantation to ensure robust remyelination of lesions and to deliver therapeutic factors in the CNS. In the present study, macaque Schwann cells expressing green fluorescent protein (GFP) were infected with human immunodeficiency virus-derived vectors overexpressing brain-derived neurotrophic factor (BDNF) or Neurotrophin 3 (NT-3), two neurotrophins that also modulate glial cell biology. The ability of transgenic Schwann cells to secrete growth factors was assessed by ELISA and showed 35- and 62-fold increases in BDNF and NT-3, respectively, in transduced macaque Schwann cell supernatants. Conditioned media of BDNF- and NT-3-transduced Schwann cells reduced Schwann cell proliferation and favored their differentiation in vitro. Transgenic cells were grafted in demyelinated spinal cords of adult nude mice. Two behavioral assays showed that NT-3- and BDNF-transduced Schwann cells promoted faster and stronger functional recovery than GFP-transduced Schwann cells. Morphological analysis indicated that functional recovery correlated with enhanced proliferation and differentiation of resident oligodendrocyte progenitors and enhanced oligodendrocyte and Schwann cell differentiation. Moreover, NT-3-transduced Schwann cells provided neuroprotection and reduced astrogliosis. These results underline the potential therapeutic benefit of combining neuroprotection and activation of myelin-forming cells to restore altered functions in demyelinating diseases of the CNS.

Animals↗
PubMed2006

Foxp3-transduced polyclonal regulatory T cells protect against chronic renal injury from adriamycin.

Chronic proteinuric renal injury is a major cause of ESRD. Adriamycin nephropathy is a murine model of chronic proteinuric renal disease whereby chemical injury is followed by immune and structural changes that mimic human disease. Foxp3 is a gene that induces a regulatory T cell (Treg) phenotype. It was hypothesized that Foxp3-transduced Treg could protect against renal injury in Adriamycin nephropathy. CD4+ T cells were transduced with either a Foxp3-containing retrovirus or a control retrovirus. Foxp3-transduced T cells had a regulatory phenotype by functional and phenotypic assays. Adoptive transfer of Foxp3-transduced T cells protected against renal injury. Urinary protein excretion and serum creatinine were reduced (P<0.05), and there was significantly less glomerulosclerosis, tubular damage, and interstitial infiltrates (P<0.01). It is concluded that Foxp3-transduced Treg cells may have a therapeutic role in protecting against immune injury and disease progression in chronic proteinuric renal disease.

Animals↗
PubMed2001

Chemoprotection and selection by chemotherapy of multidrug resistance-associated protein-1 (MRP1) transduced cells.

Utilization of chemotherapy for treatment of tumors is mainly limited by its hematological toxicity. Because of the low level expression of drug resistance genes, transduction of hematopoietic progenitors with multidrug resistance 1 (MDR1) or multidrug resistance-associated protein 1 (MRP1) genes should provide protection from chemotherapy toxicity. Successful transfer of drug resistance genes into hematopoietic cells might allow the administration of higher doses of chemotherapy and, therefore, increase regression of chemosensitive tumors. In addition, this approach can be used to select in vivo transduced cells by their enrichment after administration of cytotoxic drugs. Our group has studied the potential value of MRP1 to protect hematopoietic cells. The interest in the use of MRP1 as an alternative to MDR1 gene transfer for bone marrow protection lies in its different modulation. Indeed, classical P-gp reversal agents, tested in clinic to decrease MDR1 tumor resistance, have little or no effect on MRP1 function. This would allow, in the same patient, the use of reversal agents to decrease P-gp tumor resistance without reversing bone marrow protection of the transduced hematopoietic cells provided by MRP1. We constructed two different MRP1-containing vectors with either the Harvey retroviral long terminal repeat (LTR) or phosphoglycerate kinase (PGK) as promoters and generated ecotropic producer cells. MRP1 transduced fibroblasts were more resistant to doxorubicin, vincristine, and etoposide and their chemoprotection was increased after selection with chemotherapeutic agents in the presence of glutathione, a co-factor for MRP1 function. Lethally irradiated mice were engrafted with bone marrow (BM) cells transduced with MRP1 vectors (PGK promoter). We demonstrated that high expression of MRP1 in murine hematopoietic cells reduces doxorubicin-induced leukopenia and mortality. In addition, in vivo selection of MRP1-transduced BM cells was achieved following doxorubicin administration and allowed a better chemoprotection after the second chemotherapy cycle.

3T3 Cells↗
PubMed2001

The generation of both T killer and Th cell clones specific for the tumor-associated antigen HER2 using retrovirally transduced dendritic cells.

Induction of antitumor immunity involves the presence of both CD8(+) CTLs and CD4(+) Th cells specific for tumor-associated Ags. Attempts to eradicate cancer by adoptive T cell transfer have been limited due to the difficulty of generating T cells with defined Ag specificity. The current study focuses on the generation of CTL and Th cells against the tumor-associated Ag HER2 using autologous dendritic cells (DC) derived from CD34(+) hematopoietic progenitor cells which have been retrovirally transduced with the human epidermal growth factor receptor 2 (HER2) gene. HER2-transduced DC elicited HER2-specific CD8(+) CTL that lyse HER2-overexpressing tumor cells in context of distinct HLA class I alleles. The induction of both HLA-A2 and -A3-restricted HER2-specific CTL was verified on a clonal level. In addition, retrovirally transduced DC induced CD4(+) Th1 cells recognizing HER2 in context with HLA class II. HLA-DR-restricted CD4(+) T cells were cloned that released IFN-gamma upon stimulation with DC pulsed with the recombinant protein of the extracellular domain of HER2. These data indicate that retrovirally transduced DC expressing the HER2 molecule present multiple peptide epitopes and subsequently elicit HER2-specific CTL and Th1 cells. The method of stimulating HER2-specific CD8(+) and CD4(+) T cells with retrovirally transduced DC was successfully implemented for generating HER2-specific CTL and Th1 clones from a patient with HER2-overexpressing breast cancer. The ability to generate and expand HER2-specific, HLA-restricted CTL and Th1 clones in vitro facilitates the development of immunotherapy regimens, in particular the adoptive transfer of both autologous HER2-specific T cell clones in patients with HER2-overexpressing tumors without the requirement of defining immunogenic peptides.

Alleles↗
PubMed2001

Retrovirally transduced human dendritic cells can generate T cells recognizing multiple MHC class I and class II epitopes from the melanoma antigen glycoprotein 100.

Involvement of tumor-Ag specific CD4(+) and CD8(+) T cells could be critical in the generation of an effective immunotherapy for cancer. In an attempt to optimize the T cell response against defined tumor Ags, we previously developed a method allowing transgene expression in human dendritic cells (DCs) using retroviral vectors. One advantage of using gene-modified DCs is the potential ability to generate CD8(+) T cells against multiple class I-restricted epitopes within the Ag, thereby eliciting a broad antitumor immune response. To test this, we generated tumor-reactive CD8(+) T cells with DCs transduced with the melanoma Ag gp100, for which a number of HLA-A2-restricted epitopes have been described. Using gp100-transduced DCs, we were indeed able to raise T cells recognizing three distinct HLA-A2 epitopes within the Ag, gp100(154-162), gp100(209-217), and gp100(280-288). We next tested the ability of transduced DCs to raise class II-restricted CD4(+) T cells. Interestingly, stimulation with gp100-transduced DCs resulted in the generation of CD4(+) T cells specific for a novel HLA-DRbeta1*0701-restricted epitope of gp100. The minimal determinant of this epitope was defined as gp100(174-190) (TGRAMLGTHTMEVTVYH). These observations suggest that retrovirally transduced DCs have the capacity to present multiple MHC class I- and class II-restricted peptides derived from a tumor Ag, thereby eliciting a robust immune response against that Ag.

Amino Acid Sequence↗
PubMed2005

Primary human lymphocytes transduced with NY-ESO-1 antigen-specific TCR genes recognize and kill diverse human tumor cell lines.

cDNAs encoding TCR alpha- and beta-chains specific for HLA-A2-restricted cancer-testis Ag NY-ESO-1 were cloned using a 5'RACE method from RNA isolated from a CTL generated by in vitro stimulation of PBMC with modified NY-ESO-1-specific peptide (p157-165, 9V). Functionality of the cloned TCR was confirmed by RNA electroporation of primary PBL. cDNA for these alpha- and beta-chains were used to construct a murine stem cell virus-based retroviral vector, and high titer packaging cell lines were generated. Gene transfer efficiency in primary T lymphocytes of up to 60% was obtained without selection using a method of precoating retroviral vectors onto culture plates. Both CD4(+) and CD8(+) T cells could be transduced at the same efficiency. High avidity Ag recognition was demonstrated by coculture of transduced lymphocytes with target cells pulsed with low levels of peptide (<20 pM). TCR-transduced CD4 T cells, when cocultured with NY-ESO-1 peptide pulsed T2 cells, could produce IFN-gamma, GM-CSF, IL-4, and IL-10, suggesting CD8-independent, HLA-A2-restricted TCR activation. The transduced lymphocytes could efficiently recognize and kill HLA-A2- and NY-ESO-1-positive melanoma cell lines in a 4-h (51)Cr release assay. Finally, transduced T cells could efficiently recognize NY-ESO-1-positive nonmelanoma tumor cell lines. These results strongly support the idea that redirection of normal T cell specificity by TCR gene transfer can have potential applications in tumor adoptive immunotherapy.

Adoptive Transfer↗
PubMed1999

Gene-enhanced tissue engineering: applications for bone healing using cultured periosteal cells transduced retrovirally with the BMP-7 gene.

Periosteum has cell populations, including osteoprogenitor and chondroprogenitor cells, that can be grown in cell culture and form both bone and cartilage under appropriate conditions. The authors have shown previously that cultured periosteal cells can be used in the tissue engineering of bone, and they demonstrated substantial bone formation in a rabbit cranial defect model. In the current study, principles of tissue engineering were combined with principles of gene therapy to produce cultured periosteal cells transduced retrovirally with the bone morphogenetic protein 7 (BMP-7) gene to be used in the treatment of bone defects. Human BMP-7 complementary deoxyribonucleic acid was generated from a cell line using reverse transcription polymerase chain reaction and cloned into a retroviral vector plasmid. Retroviral vector particles were then used to transduce New Zealand White rabbit periosteal cells. Transduced periosteal cells demonstrated substantial production of both BMP-7 messenger ribonucleic acid by Northern blot analysis and BMP-7 protein by enzyme-linked immunosorbent assay. These cells were then seeded into polyglycolic acid (PGA) matrices and used to repair critical-size rabbit cranial defects. At 12 weeks, defect sites repaired with BMP-7-transduced periosteal cells/PGA had significantly increased radiographic and histological evidence of bone repair compared with those defect sites repaired with negative control-transduced cells/PGA, nontransduced cells/PGA, PGA alone, or unrepaired defects. Thus, this study demonstrates successfully a tissue engineering approach to bone repair using genetically modified cells.

Animals↗
PubMed2000

Lentivirus-based vectors transduce mouse hematopoietic stem cells with similar efficiency to moloney murine leukemia virus-based vectors.

The low levels of transduction of human hematopoietic stem cells (HSCs) with Moloney murine leukemia virus (MLV) vectors have been an obstacle to gene therapy for hematopoietic diseases. It has been demonstrated that lentivirus vectors are more efficient than MLV vectors at transducing nondividing cell lines as well as human CD34(+) cells and severe combined immunodeficiency disease repopulating cells. We compared transduction of cell lines and Lin(-) bone marrow cells, using a vesicular stomatitis virus G (VSV-G)-pseudotyped lentivirus or MLV vectors carrying a green fluorescent protein marker gene. As predicted, the lentivirus vector was more efficient at transducing mouse and human growth-inhibited cell lines. The transduction of mouse HSC by lentivirus vectors was compared directly to MLV vectors in a co-transduction assay. In this assay, transduction by ecotropic MLV is a positive internal control for downstream steps in retrovirus transduction, including cell division. Both the VSV-G lentivirus and MLV vectors transduced mouse HSCs maintained in cytokine-free medium at very low frequency, as did the ecotropic control. The lentivirus vector and the MLV vector were equally efficient at transducing bone marrow HSCs cultured in interleukin 3 (IL-3), IL-6, and stem cell factor for 96 hours. In conclusion, although lentivirus vectors are able to transduce growth-inhibited cell lines, the cell cycle status of HSCs render them resistant to lentivirus-mediated transduction, and it is hypothesized that entry into cycle, not necessarily division, may be a requirement for efficient lentivirus-mediated transduction.

3T3 Cells↗
PubMed2001

Expression of transduced HSP70 gene protects chondrocytes from stress.

OBJECTIVE: To investigate the efficacy of adenovirus vector mediated transduction of heat shock protein 70 (HSP70) gene to human chondrocyte-like cell (HCS-2/8) against heat stress. METHODS: Two adenovirus vectors that contain wild-type (AxSHEwt) or mutant-type (AxSHEmt) HSP70 gene, and that are regulated by SRalpha promoter, were constructed. The mutant-type lacks the area that expresses stress durability. One of the 2 adenovirus vectors was added to the cultures of human chondrocyte-like cells (HCS-2/8). Heat stress (48 degrees C) was applied to the transduced cells for 2 h, and the efficacy of adenovirus vector mediated transduction of HSP70 gene against heat stress in the chondrocytes was investigated using alamar blue assay and MTT assay. RESULTS: Absorbance levels at 48 degrees C were 300.3 +/- 51.9 and 1.173 +/- 0.011 in the controls, 278.5 + 33.8 and 1.217 +/- 0.018 in the AxSHEmt transduced cells, and 349 +/- 14.7 and 1.371 +/- 0.033 in the AxSHEwt transduced cells. The level in the AxSHEwt transduced cells was significantly higher than in the other 2 groups (p < 0.05). With 37 degrees C treatment, no significant difference was observed. CONCLUSION: Chondrocytes to which HSP70 gene was transduced had a significantly higher metabolic activity and viability under heat stress.

Adenoviridae↗
PubMed2002

[Expression of enhanced green fluorescent protein in transduced variant HT-29c cells in vitro and in vivo].

OBJECTIVE: To evaluate the gene transfer and expression of enhanced green fluorescent protein (EGFP) in retrovirally transducted variant HT-29c cells in vitro and in vivo. METHODS: The retroviral vector prkat EGFP/neo was constructed and was transfected into the 293T cell using a standard calcium phosphate precipitation method. HT-29c cells (in vivo selected HT-29 cells) were transduced by a retroviral vector encoding the EGFP gene. The fluorescence intensity of colorectal carcinoma HT-29c cells after transfected with the EGFP gene bearing retrovirus was visualized using fluorescence microscope and fluorescence activated cell sorter analysis. Multiple biological behaviors of transduced cells such as the proliferating potential and the expression of various antigens were comparatively analyzed between untransfected and transfected in vitro. EGFP expression of the fresh tumor tissue was assessed in vivo. RESULTS: After being transduced, HT-29c cells with the EGFP gene displayed a stable and long-term EGFP expression under the nonselective conditions in vitro. After culturing cells successively to passage 50 in vitro, EGFP expression level was still high. Their biological behaviors, such as expression of tumor antigens, proliferation rate and aggregation capability were not different compared to untransfected parental cells in vitro. In subcutaneous tumors, EGFP was stable and highly expressed. CONCLUSIONS: An EGFP expressing retroviral vector was used to transduce HT-29c cells. The transduced cells show a stable and long-term EGFP expression in vitro and in vivo. These cells are a valuable tool for in vivo analysis of metastatic spread.

Animals↗
PubMed1992

In vivo activity of tumor necrosis factor (TNF) mutants. Secretory but not membrane-bound TNF mediates the regression of retrovirally transduced murine tumor.

We have previously demonstrated that murine tumor cells transduced with a retrovirus containing the cDNA encoding wild-type human TNF regress in vivo when injected into immunocompetent mice; this regression is T cell mediated. To determine whether membrane-associated or secreted TNF was responsible for tumor regression, we transduced a cloned murine fibrosarcoma 205 F4 with retroviruses encoding modified human TNF genes. The cloned tumor lines of one retroviral transduction expressed only membrane bound 26-kDa TNF. This TNF could not be cleaved or secreted, but was present on the cell surface. A second retrovirus caused the expression of only secretory 17-kDa TNF, as the transmembrane domain of the cDNA was deleted. The TNF produced by tumor cells transduced with either retroviral vector was functional in vitro as direct lysis of the TNF-sensitive target L929 by transduced tumor cells was demonstrated. The TNF present on 26-kDa expressing tumors was membrane bound as supernatants from cultured 17-kDa TNF expressing tumor cells but not 26-kDa TNF expressing tumors mediated the lysis of L929 cells. Both tumors were injected s.c. into syngeneic mice and tumor growth was measured serially. In repeated experiments, 26-kDa TNF expressing tumors grew progressively in all mice. In contrast, 17-kDa TNF expressing tumors grew for 10 days and then regressed with all animals free of tumor at 28 days. Tumor regression was abrogated by in vivo injection of an anti-TNF antibody. Similar results were obtained in a second tumor model, 203 E4. Thus regression of TNF transduced tumors in vivo requires secretion of TNF, as membrane-bound TNF is insufficient to elicit the host response.

Animals↗
PubMed1979

[New transducing phage with RNA polymerase beta- and beta'-subunit genes derived from a hybrid phage lambda att80: isolation, genetic analysis and physical mapping].

A hybrid lambda att 80 phage with the genetic structure lambda (A-J) phi 80 (att-int-xis) imm lambda..cI857s7 is shown to be a convenient vector for creating transducing phages. On the one hand, the restriction analysis indicates that it has 3 restriction sites for EcoRI in comparison with 5 and 9 sites for parental phages lambda and phi 80 respectively. On the other hand, its buoyant density is less than that of phage lambda and under centrifugation it is easier separated from the phage transducing particles. When lambda att 80 prophage was excluded from the bfe locus of Escherichia coli, transducing phages with genes of two RNA polymerase beta-subunits (rpoB and rpoC) were isolated. To identify the latter, a convenient genetic test was worked out. A physical map of lambda att 80 drifd 35 transducing phage, carrying rpoB and rpoC genes has been constructed using endonucleases EcoRI and HindIII. A comparison of this map and the corresponding maps of transducing phages lambda drifd 18 and lambda drifd 47, studied earlier, led to the discovery of two integration sites of phage lambda within the locus bfe spaced apart by about 1800 nucleotide pairs. At all the sites both phages (lambda and lambda att 80) have integrated in the locus bfe in the counter clockwise order.

Bacteriophage lambda↗
PubMed1995

Preselection of transduced murine hematopoietic stem cell populations leads to increased long-term stability and expression of the human multiple drug resistance gene.

We have been using the human multiple drug resistance (MDR) gene to transduce murine hematopoietic cells via retroviruses as a model system for potential human gene therapy. In this paper, we show that transplantation of MDR-transduced midgestational fetal liver cells (FLCs) into lethally irradiated mice leads to the continued presence and expression of the human MDR gene in the short-lived granulocyte-macrophages of recipients' peripheral blood (PB) for up to 12 months. We have also shown the ability of this retroviral system to efficiently transduce several murine FLC subpopulations enriched for hematopoietic stem cells (FL-HSCs) both (1) short-term by MDR-polymerase chain reaction analysis of individual day 12 colony-forming unit-spleen and (2) long-term by in vivo maintenance of MDR and expression of its product, p-glycoprotein, up to 1 year in PB. More highly enriched FL-HSC subpopulations show the greatest number of circulating granulocyte-macrophage cells expressing MDR long-term. These studies also show that preselection by fluorescence-activated cell sorting of MDR-transduced and -expressing cells before transplant significantly increases the percentage of circulating granulocyte-macrophage cells that express MDR at all time points analyzed posttransplant as compared with unsorted cells transduced in the same manner (P < .01). These results have potentially significant implications for future human gene therapy trials.

3T3 Cells↗
PubMed1994

Helper T cell-independent proliferation of CD8+ cytotoxic T lymphocytes transduced with an IL-1 receptor retrovirus.

Although the proliferation of CD8+ CTL typically requires cytokine support provided by helper T cells, a subset of naturally occurring CD8+ CTL are capable of proliferating independently of T cell help. Such helper-independent CTL have previously been shown to possess IL-1 receptors (IL-1R) and to proliferate in response to IL-1 through endogenous production of IL-2. In this study, we have transduced conventional helper-dependent CTL clones with a retroviral vector encoding the murine type I IL-1R. Transduced CTL selected in G418 expressed vector-derived transcripts encoding IL-1R and displayed approximately 1000 cell surface receptors with an IL-1 affinity typical for the type I IL-1R. In contrast to parental cells, transduced CTL proliferated in response to IL-1 in the presence of Ag, without a requirement for helper T cells, IL-2, or other cytokine support. Stimulation with both IL-1 and Ag was necessary for the proliferative response. No endogenous synthesis of IL-2 could be detected in the IL-1R transduced cells in response to IL-1 stimulation, in the presence or absence of Ag. The IL-1R-induced phenotype was demonstrated in two independent T cell clones, both of which retained Ag-specific cytolytic activity. No such conversion to a helper-independent phenotype was induced by a retroviral vector encoding only the neo gene. The behavior of the IL-1R-transduced CTL in proliferation assays thus resembled that of the naturally occurring helper-independent CTL.

Animals↗
PubMed1994

Comparison of transducer placement sites for Doppler echocardiography in dogs with subaortic stenosis.

Effects of transducer placement site and various operators on Doppler echocardiographic measures were evaluated in 12 dogs with subaortic stenosis. Dogs sedated by IV administration of acepromazine and buprenorphine were examined by 2 observers. Maximal aortic velocity and aortic velocity time integral were determined from Doppler aortic velocity spectra recorded, using a 1.9-MHz continuous wave nonimaging transducer placed at 3 echocardiographic sites: left ventricular apex (LA), suprasternal notch (SSN), and subcostal (SC). Doppler-estimated left ventricular-to-aortic pressure gradients were calculated from the traced velocity spectra by application of the modified Bernoulli equation. Each observer recorded high-quality Doppler spectral signals in all dogs from the SC and LA transducer sites and in 83% of dogs from the SSN window. Mean values for maximal aortic velocity and velocity time integral differed among sites (P < 0.05), but not between observers. Maximal velocity and velocity time integral measured from the SC transducer site were higher than those measured from the SSN or LA positions. Presumably, SC transducer placement provided the highest aortic velocities because of optimal alignment with aortic outflow. The maximal pressure gradient estimated from SC velocities exceeded SSN values by 27 mm of Hg and LA measurements by 38 mm of Hg. In this study, the optimal site for the Doppler echocardiographic detection of subaortic stenosis and assessment of this lesion's hemodynamic importance in most affected dogs was the SC position.

Analysis of Variance↗
PubMedDate not supplied

Therapeutic efficacy of T cells derived from lymph nodes draining a poorly immunogenic tumor transduced to secrete granulocyte-macrophage colony-stimulating factor.

We examined the host immune response to the poorly immunogenic B16-BL6 melanoma, which was transduced to secrete granulocyte-macrophage colony-stimulating factor (GM-CSF) (450 ng/10(6)/24 h). Tumor growth after subcutaneous inoculation was not significantly altered, although an influx of neutrophils and monocytes/macrophages was evident within tumors and draining lymph nodes (LNs). Immunization with irradiated transduced cells did not induce systemic immunity to the parental tumor. However, vaccination with transduced tumors significantly augmented in vivo sensitization of draining LN cells. These tumor-draining LN (TDLN) cells, when secondarily stimulated in vitro with anti-CD3 monoclonal antibodies and expanded in interleukin-2 (10 U/ml), exhibited greater release of GM-CST and interferon-gamma against tumor compared with TDLN cells from animals with parental tumor. In adoptive immunotherapy, activated LN cells draining transduced tumors mediated significant reductions of the numbers of established pulmonary metastases compared with LN cells draining parental tumor, which were ineffective. In addition, the therapeutic efficacy of LN cells draining transduced tumors was significantly better than LN cells primed in vivo with tumor cells admixed with Corynebacterium parvum, which we have previously described as an approach to generate immune cells. Thus, GM-CSF appears to be an important adjuvant in the induction of tumor immunity.

Animals↗
PubMedDate not supplied

Use of bicistronic retroviral vectors encoding the LacZ gene together with a gene of interest: a method to select producer cells and follow transduced target cells.

The coordinate expression of a marker gene and a therapeutic gene in one retroviral vector has considerable advantages. High-titer producer lines can potentially be selected on the basis of marker gene expression, and the expression of transduced genes in target cells can readily be followed. Moreover, target cells with stable high expression can be selected before use in therapeutic protocols or research questions. We used internal ribosomal entry site (IRES) sequences to express two genes in the same retroviral vector. We used the LacZ gene as the marker gene and the cytokine interleukin (IL)-7 or dominant negative (dn) forms of the T-cell tyrosine kinases ZAP-70 and lck as genes of interest. Amphotropic packaging cells transfected with MFG-IL-7-IRES-LacZ, MFG-dnZAP-70-IRES-LacZ, or MFG-dnlck-IRES-LacZ were sorted on the basis of beta-galactosidase expression. These LacZ-positive producer cells also expressed the gene of interest, produced high-titer retrovirus, and were capable of efficiently transducing Jurkat T cells and T-cell clones. When MFG-IL-7-IRES-LacZ-transduced Jurkat T cells were sorted on the basis of LacZ expression, a positive correlation with the amount of IL-7 produced by these cells was found. This demonstrates that selection of the LacZ marker gene also selects for cells that express the gene of interest at high levels. Moreover, T cells transduced with the dn tyrosine kinases and selected on the basis of LacZ expression showed functional alterations after T-cell receptor stimulation, demonstrating that retrovirally transduced signaling molecules can alter the function of T cells.

DNA Primers↗
PubMedDate not supplied

Coexpression of a multidrug resistance gene (MDR1) and herpes simplex virus thymidine kinase gene in a bicistronic retroviral vector Ha-MDR-IRES-TK allows selective killing of MDR1-transduced human tumors transplanted in nude mice.

Ha-MDR-IRES-TK is a bicistronic vector that coexpresses the MDR1 gene and the herpes simplex virus thymidine kinase (HSV-TK) gene. In the present study we examined the effect of ganciclovir on MDR1-positive tumors that have been transduced with Ha-MDR-IRES-TK. To establish a human tumor xenograft model of MDR1-transduced recurrent tumors, human KB-3-1 carcinoma cells were transduced with HaMDR or Ha-MDR-IRES-TK, and one each of representative clones, termed KB/MDR and KB/MDR-TK, respectively, were isolated. KB/MDR and KB/MDR-TK showed similar levels of multidrug resistance in vitro. Vinblastine strongly inhibited the growth of the parental KB-3-1 tumors in nude mice but showed little or no effect against KB/MDR-TK tumors. Ganciclovir inhibited the in vivo growth of KB/MDR-TK tumors almost completely under conditions that did not affect the growth of KB-3-1 tumors. Coadministration of vinblastine and ganciclovir inhibited the in vivo growth of KB/MDR-TK premixed with KB-3-1 at any ratio. Long-term, high-level expression of human P-glycoprotein was observed in peripheral blood cells of mice transplanted with Ha-MDR-IRES-TK-transduced bone marrow cells. Ganciclovir eliminated the P-glycoprotein-positive normal blood cells. However, no systemic toxicity was observed. These results clearly demonstrate that it is possible to use ganciclovir to treat MDR1-positive tumors that have been unintentionally transduced with Ha-MDR-IRES-TK. This safety-modified vector should be useful for introducing the MDR1 gene into bone marrow cells to protect normal cells from the toxic effects of cancer chemotherapy.

ATP Binding Cassette Transporter, Subfamily B, Mem↗