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Herpes Simplex Virus Thymidine Kinase (herpes + simplex_virus_thymidine_kinase)
Selected AbstractsWater spin dynamics during apoptotic cell death in glioma gene therapy probed by T1, and T2,MAGNETIC RESONANCE IN MEDICINE, Issue 6 2008A. Sierra Abstract Longitudinal and transverse relaxations in the rotating frame, with characteristic time constants T1, and T2,, respectively, have potential to provide unique MRI contrast in vivo. On-resonance spin-lock T1, with different spin-lock field strengths and adiabatic T2, with different radiofrequency-modulation functions were measured in BT4C gliomas treated with Herpes Simplex Virus thymidine kinase (HVS-tk) gene therapy causing apoptotic cell death. These NMR tools were able to discriminate different treatment responses in tumor tissue from day 4 onward. An equilibrium two-site exchange model was used to calculate intrinsic parameters describing changes in water dynamics. Observed changes included increased correlation time of water associated with macromolecules and a decreased fractional population of this pool. These results are consistent with destructive intracellular processes associated with cell death and the increase of extracellular space during the treatment. Furthermore, association between longer exchange correlation time and decreased pH during apoptosis is discussed. In this study, we demonstrated that T1, and T2, MR imaging are useful tools to quantify early changes in water dynamics reflecting treatment response during gene therapy. Magn Reson Med 59:1311,1319, 2008. © 2008 Wiley-Liss, Inc. [source] Evaluation of combined gene regulatory elements for transcriptional targeting of suicide gene expression to malignant melanomaEXPERIMENTAL DERMATOLOGY, Issue 6 2003Heike Rothfels Abstract:, Selective killing of tumors can be achieved by targeting the transcription of suicide genes via specific DNA control elements to malignant cells. Three different enhancer-promoter systems were constructed and evaluated for their capability to direct gene expression to melanoma. Two tissue-specific (tyrosinase and MIA) promoters and one weak viral promoter were fused to multiple tandem copies of a melanocyte-specific enhancer element. Reporter gene assays revealed a maximum increase in transcription by combining each promoter with 3,4 copies of the enhancer and demonstrated that all enhancer-promoter combinations exhibited tissue-specific activity. Though this activity was still significantly less than that of the strong but unspecific cytomegalo virus (CMV) promoter. In contrast, when these combinations were employed to drive the expression of two suicide genes, encoding the diphtheria toxin A chain (DT-A) and the prodrug-activating herpes simplex virus thymidine kinase (TK), respectively, only those constructs in which transcription was under the control of tissue-specific promoter elements mediated selective killing of melanoma cells. This killing was in the range of cell death induced by CMV promoter activity. Our data indicate that the enhancer/tyrosinase and enhancer/MIA promoter constructs but not the viral promoter constructs can provide a valuable tool for selective suicide gene expression in melanoma. [source] A designed curved DNA segment that is a remarkable activator of eukaryotic transcriptionFEBS JOURNAL, Issue 24 2006Noriyuki Sumida To identify artificial DNA segments that can stably express transgenes in the genome of host cells, we built a series of curved DNA segments that mimic a left-handed superhelical structure. Curved DNA segments of 288 bp (T32) and 180 bp (T20) were able to activate transcription from the herpes simplex virus thymidine kinase (tk) promoter by approximately 150-fold and 70-fold, respectively, compared to a control in a transient transfection assay in COS-7 cells. The T20 segment was also able to activate transcription from the human adenovirus type 2 E1A promoter with an 18-fold increase in the same assay system, and also activated transcription from the tk promoter on episomes in COS-7 cells. We also established five HeLa cell lines with genomes containing T20 upstream of the transgene promoter and control cell lines with T20 deleted from the transgene locus. Interestingly, T20 was found to activate transcription in all the stable transformants, irrespective of the locus. This suggests that the T20 segment may allow stable expression of transgenes, which is of importance in many fields, and may also be useful for the construction of nonviral vectors for gene therapy. [source] In vivo efficacy of HSV-TK transcriptionally targeted to the tumour vasculature is augmented by combination with cytotoxic chemotherapyTHE JOURNAL OF GENE MEDICINE, Issue 3 2005Georgia Mavria Abstract Background Retroviral vectors are suitable for targeting endothelial cells in the tumour neovasculature because of their intrinsic selectivity for proliferating cells. Previously, we inserted regulatory elements of the endothelial-specific prepro-endothelin-1 (ppET1) promoter in retroviral vectors to generate high-titre, replication-defective recombinant retroviruses that restricted gene expression to the vascular compartment of tumours. Methods A retroviral vector was generated in which expression of herpes simplex virus thymidine kinase (HSV-TK) was transcriptionally restricted to endothelial cells, under the control of a hybrid ppET-1 LTR. Xenograft tumour models were used to determine the efficacy of targeting HSV-TK to the tumour vasculature. Subsequently, vascular-targeted gene therapy was combined with chemotherapeutic agents. Results Breast or colorectal xenograft tumour growth was reduced and survival was increased in response to ganciclovir treatment. Treatment resulted in widespread vascular disruption and tumour cell apoptosis. In colorectal tumours, combination with irinotecan, a cytotoxic drug used to treat colorectal cancer, significantly increased survival compared to drug alone. No beneficial effect on survival was observed when combined with cisplatin, a cytotoxic drug not in clinical use for this tumour type. On the basis of their relative efficacies in vitro against tumour and endothelial cells, co-operativity with irinotecan likely derives from additionally targeting the peripheral tumour cells that survive the anti-vascular treatment. Conclusions We show that the ppET1-targeted vector is efficacious for therapeutic gene expression in vivo, validating a strategy targeted to tumour vasculature, and demonstrate that vascular targeting combined with appropriate chemotherapy is more effective than either therapy alone. Copyright © 2004 John Wiley & Sons, Ltd. [source] Cytotoxicity and antiangiogenesis by fibroblast growth factor 2,targeted Ad-TK cancer gene therapy,THE LARYNGOSCOPE, Issue 4 2009Koichiro Saito MD Abstract Objectives: Human head and neck squamous cell carcinoma (HNSCC) in addition to lung, skin, ovarian, and other cancers overexpress fibroblast growth factor (FGF) receptors on both individual tumor cells and endothelial cells within the tumor microenvironment. The purpose of this study was to investigate whether FGF2-targeted gene therapy could redirect adenoviral vectors encoding the herpes simplex virus thymidine kinase gene (Ad-TK) to FGF receptors on tumor and endothelial cells with the intent of improving both the efficiency of transgene expression and the antitumor response. Study Design and Methods: An Ad-TK vector consisting of a conjugate of FGF2 linked to a Fab, fragment against the adenoviral knob region was directly delivered to human HNSCC xenograft tumors in nude mice, which were subsequently dosed with ganciclovir. Tumor specimens were assessed for herpes simplex virus thymidine kinase (HSV- tk) transgene mRNA expression, FGF1/2 receptor expression, terminal deoxynucleotidyl transferase biotin,deoxy uridine triphosphate nick end labeling assay for apoptosis, CD31 immunohistochemistry to estimate tumor microvessel density, and tumor volume change. Results: FGF2-retargeted Ad-TK gene therapy demonstrated significant increases in both HSV- tk mRNA expression and cellular apoptosis levels, and a significant decrease in tumor volume size compared with all other groups. Furthermore, microvessel density was significantly lower in the FGF2-retargeted Ad-TK group, indicating a strong antiangiogenesis effect. Conclusions: These data suggest that FGF2-retargeted Ad-TK produces a combination of expected direct antitumor cytotoxicity and a newly reported antiangiogenesis effect that could prove promising as a novel therapeutic approach in the treatment of FGF receptor,expressing cancers. Laryngoscope, 2009 [source] Retrovirus-mediated transfer of the herpes simplex virus thymidine kinase and enhanced green fluorescence protein genes in primary T lymphocytesBRITISH JOURNAL OF HAEMATOLOGY, Issue 4 2000Sabrina Di Florio The EGFP-tk retroviral vector, encoding enhanced green fluorescent protein (EGFP) and the herpes simplex virus thymidine kinase (HSV-tk) packaged in a Phoenix amphotropic cell line, was used to transduce healthy donor T lymphocytes. Infection yielded a mean of 41·8 ± 9·3% SD (range 31·1,48·4%) EGFP-positive cells and a mean of 92 ± 2% SD (range 90,94%) after cell sorting. EGFP expression remained stable for 30 d after infection. The entire gene transfer procedure had no significant effect on lymphocyte subsets and slightly reduced clonogenicity. Ganciclovir (gcv) treatment (1 µg/ml × 10 d) killed all EGFP-positive cells in the transduced and transduced/sorted populations, but had no effect on untransduced controls. Our results show that primary T lymphocytes can be transduced using an EGFP-tk vector that yields a homogeneous infected population without affecting lymphocyte subsets, function and clonogenicity. [source] | ||||||||||