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Query: UMLS:C0025202 (melanoma)
 69,561 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Recent experiments with genetically engineered tumors have generated renewed interest in active cellular immunotherapy as a cancer treatment modality. In order to consider the use of live tumor cells for immunotherapy in human cancer patients, it will be important to ensure that these cells do not themselves produce morbidity in the event the immune system fails to eliminate them. Toward this end, we have examined a strategy for eliminating genetically manipulated nonimmunogenic tumors in vivo. When B16F10 melanoma cells were transfected with the Herpes simplex virus 1 thymidine kinase (HSV-TK) gene, cells were rendered susceptible to killing by the nucleoside analogs acyclovir (ACV) and ganciclovir (GCV). B16-HSV-TK+ tumors established in C57BL6 mice were successfully "suicided" in vivo when GCV was administered by continuous infusion. However, late recurrences were observed even after 1 month of continuous GCV treatment. In vivo growth kinetics suggested that the recurrences resulted from a tiny number (< 20) of cells that had survived the GCV treatment. Interestingly, recurrent tumors were as sensitive to GCV as the parental B16-HSV-TK+ line. While these results demonstrate potential feasibility of the suicide gene strategy for active immunotherapy with live tumor cells, they also illustrate that approaches dependent on the intracellular generation of cell cycle-dependent toxins may fail to eliminate small numbers of cells that temporarily exit cell cycle or that are pharmacologically sequestered.
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PMID:Herpes simplex-1 virus thymidine kinase gene is unable to completely eliminate live, nonimmunogenic tumor cell vaccines. 133 54

A serum-dependent and two serum-independent variants of the Bowes melanoma cell line, RPMI7272, were transfected with plasmids containing a geneticin-resistance (neo) gene transcribed by the HSV thymidine kinase promoter and an SV40 T antigen gene under control of the mouse metallothionein I promoter. T-antigen increased the cloning efficiency of the serum-dependent cell line in soft-agar more than 50-fold, but cloning efficiency of serum-independent lines was not increased. Trypsinization of serum-independent lines required 100 times lower concentrations of trypsin than serum-dependent cells. Human metal-inducible T-antigen-producing (HMT) melanoma cells supported replication of transfected plasmids containing an SV40 origin of replication. Transient expression of interferon or plasminogen activator from such plasmids was 40-fold higher than in untransformed melanoma cells and could be enhanced 30-fold more by stimulation of transcription of the T antigen gene with cadmium chloride. HMT cells can be grown in suspension and thus may represent an attractive alternative to monkey kidney COS cells.
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PMID:Transformation of Bowes melanoma cells with SV40 T antigen. 136 20

Activity of replicase complex enzymes involving thymidine kinase (TK), ribonucleotide reductase (RR), DNA-polymerases alpha and beta as well as DNA synthesis and single breaks in DNA were studied during growth of P388 ascites tumor. Under these conditions the rate of DNA synthesis was distinctly decreased via salvage pathway and de novo. Single breaks were not detected in the preexistent DNA within various periods after transplantation of P338 leukemic cells. Retardation of DNA synthesis during tumor growth correlated with a decrease in TK, RR and DNA-polymerase alpha activities, while DNA-polymerase beta activity was markedly increased. Growth of melanoma B16 was accompanied by a decrease in content of ATP, ADP, NAD, phosphocreatine and phosphosaccharides as well as by an increase in the level of inorganic phosphates.
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PMID:[Changes in the replication apparatus and phosphorus-containing metabolite pool in experimental tumors in animals during development]. 181 11

The human Me14-D12 antigen is a cell surface glycoprotein regulated by interferon-gamma (IFN-gamma) on tumor cell lines of neuroectodermal origin. It consists of two non-convalently linked subunits with apparent mol. wt sizes of 33,000 and 38,000. Here we describe the molecular cloning of a genomic probe for the Me14-D12 gene using the gene transfer approach. Mouse Ltk- cells were stably cotransfected with human genomic DNA and the Herpes Simplex virus thymidine kinase (TK) gene. Primary and secondary transfectants expressing the Me14-D12 antigen were isolated after selection in HAT medium by repeated sorting on a fluorescence activated cell sorter (FACS). A recombinant phage harboring a 14.3 kb insert of human DNA was isolated from a genomic library made from a positive secondary transfectant cell line. A specific probe derived from the phage DNA insert allowed the identification of two mRNAs of 3.5 kb and 2.2 kb in primary and secondary L cell transfectants, as well as in human melanoma cell lines expressing the Me14-D12 antigen. The regulation of Me14-D12 antigen by INF-gamma was retained in the L cell transfectants and could be detected both at the level of protein and mRNA expression.
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PMID:A novel interferon-gamma regulated human melanoma-associated antigen, gp33-38, defined by monoclonal antibody Me14-D12. II. Molecular cloning of a genomic probe. 254 4

Base propenals arise from DNA by a Fe(II)-bleomycin-mediated reaction which leads to strand scission. These compounds undergo addition-elimination reactions with thiols and other nucleophilic groups under physiological conditions and form an addition product with glutathione. Thymine- and adenine-N1-propenals inhibit DNA synthesis in HeLa cells; both compounds are cytotoxic [50% inhibiting concentration (IC50) = 1 to 2 microM]. A structurally related nucleoside, thymidine-N3-propenal, designed as a metabolic pathway inhibitor, inhibits growth of HeLa, L1210 leukemia, Lewis lung carcinoma, B16 melanoma, and DLD-1 human colon carcinoma cells in culture (IC50 = 1 to 6 microM). A single injection of this compound, administered on the first day following transplant of L1210 leukemia cells, increased the mean survival time of mice by 50% (T/C = 154). Thymidine-N3-propenal selectively blocks DNA synthesis in HeLa cells and inhibits thymidine kinase (Ki = 5.1 microM) and DNA polymerase-alpha. We suggest that base propenals, rather than damaged DNA, account for some of the cytotoxic effects of bleomycin and that nucleoside propenals represent a novel class of site-directed inhibitors.
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PMID:Origin and cytotoxic properties of base propenals derived from DNA. 257 72

Carbetimer, an intermediate molecular-weight-derivatized copolymer of maleic anhydride and ethylene, has been shown to possess significant antineoplastic activity in the stem cell assay. We have examined the antitumor activity of carbetimer in vivo and in vitro against HM5-Carb/S and M21, both primary human melanoma cell lines sensitive and resistant to carbetimer, respectively. The mechanism of action of carbetimer in HM5-Carb/S has been determined. Mice bearing palpable sensitive tumors were treated with 10% lethal doses of carbetimer (1500 mg/kg i.p.). The tumor nucleotide profile was determined 4 hours later. Uridine and cytidine nucleoside triphosphates were reduced by 36.6 and 58.2%, respectively. In a similar experiment using carbetimer-resistant tumor, there was no change in the tumor pool sizes of uridine and cytidine nucleoside triphosphate pools in carbetimer- or saline-treated animals. Following 24-h exposure of the cells to 1000 microM concentration of carbetimer, the carbetimer-sensitive cells were pulsed with [14C]uridine, cytidine, or thymidine for 30 min. Pyrimidine nucleotides, in particular triphosphates, were reduced significantly as compared to the saline-treated control. Similar treatment of carbetimer-resistant cells resulted in no change in the pool sizes of the nucleotides. [14C]Bicarbonate flux studies demonstrated that [14C]CO2 conversion into UMP and CMP was increased 200 and 140% of control in the carbetimer-sensitive cells treated with 1000 microM carbetimer; however, a similar treatment of the resistant cells showed no change in the pool sizes of the nucleotide. Examination of pyrimidine salvage enzymes demonstrated that, in the sensitive cells, carbetimer treatment reduced the specific activity of uridine, cytidine, and thymidine kinase by 46, 37, and 60%. In a similar study using resistant cells, the specific activities were reduced 7 and 0%, respectively. In the restitution studies coincubation of carbetimer-sensitive cells with carbetimer and uridine resulted in essentially the reversal of carbetimer cytotoxicity. Thus, carbetimer inhibits the growth of the sensitive cells by inhibiting the uptake and metabolism of performed nucleosides both in vivo and in vitro.
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PMID:Mechanism of action of a new antitumor agent, carbetimer. 375 94

Expression systems were developed for evaluating recombinant human thrombomodulin (TM) production in different host cell lines by investigating the performance of five mammalian expression vectors. The expression vectors were constructed so that they contain multiple monocistronic gene cassettes which include a gene encoding a dominant selectable marker, HyR (hygromycin B phosphotransferase), under the regulation of the thymidine kinase promoter, the target gene which encodes a truncated human re-TM under the regulation of various promoters, an amplifiable gene (Dhfr) encoding murine dihydrofolate reductase under the regulation of either the SV40 early or late promoter along with the SV40 enhancer and the SV40 ori. We tested the performance of the five expression vectors in human embryonic kidney cells (HEK293), baby hamster kidney cells (BHK), human melanoma cells (CHL-1) and Dhfr- Chinese hamster ovary cells (CHO/Dhfr-). We found that the efficiency of DNA uptake, transient expression and stable expression of the different expression vectors were all cell-line dependent. However, the myeloproliferative sarcoma virus (MPSV) LTR promoter consistently showed higher expression levels in all cell lines, particularly in HEK293 cells. These results were confirmed by the distribution curves of the level of expression of individual clones. Furthermore, by amplifying Dhfr in transfected CHO/Dhfr- cells with 100 nM methotrexate, we achieved a 20-fold increase in re-TM production using the SV40 late promoter to control murine Dhfr expression. Our data from DNA and mRNA analysis reveal that pMPSV-TM has a high transcription efficiency.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Expression efficiency of the human thrombomodulin-encoding gene in various vector and host systems. 752 46

To target therapeutic genes specifically to melanoma cells, we have constructed recombinant retroviruses where transcriptional control of the murine interleukin-2 (mIL-2) or herpes simplex virus thymidine kinase (HSVtk) genes is provided by the 5' promoter region of the murine tyrosinase gene. Tissue-specific expression of these genes is observed both at the mRNA and protein levels in the B16 melanoma line compared with NIH3T3 fibroblasts. Thus, B16 cells infected with one such retrovirus containing the HSVtk gene exhibited a > 90% reduction in colony-forming efficiency after exposure to 1 microgram/ml ganciclovir, relative to controls, whereas similarly infected NIH3T3 cells showed < 10% reduction in colony-forming efficiency under comparable conditions. The degree of preservation of tissue-specific expression from the internal tyrosinase promoter depended upon the exact molecular design of the vector, possibly as a consequence of the interference between closely juxtaposed promoters within the provirus. Our results show that retroviral vectors can be prepared with the capacity to regulate expression of inserted genes specifically in a particular cell type and may be useful for developing efficient, targeted vectors for the in vivo delivery of genetic therapies for malignant melanoma.
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PMID:A comparison of the properties of different retroviral vectors containing the murine tyrosinase promoter to achieve transcriptionally targeted expression of the HSVtk or IL-2 genes. 758 96

Thymidine kinase (EC 2.7.1.21) is an enzyme supporting DNA synthesis under conditions of increased cell proliferation. Although it has proved to be a useful marker for various malignant diseases, it has not been tested in malignant melanoma. Thymidine kinase activity was measured by means of a radioenzymic assay in two classical animal models of melanoma disease--B16 and Cloudman S91 melanoma-bearing mice. Tumour cell proliferation was assessed histochemically by measuring the expression of proliferating cell nuclear antigen (PCNA). Tumour cytosolic specific thymidine kinase activity was found to be higher in less pigmented Cloudman S91 melanoma than in differentiated, ie pigmented B16 melanoma, relative to the proliferative activity of the two tumours. Serum thymidine kinase levels were increased in melanoma-bearing animals of both types compared with healthy mice; this also reflected the efficacy of the therapy: cyclophosphamide-treated B16 melanoma-bearing mice in which the tumour development was slowed down had significantly lower serum enzyme levels in comparison with the non-treated group and the same levels compared with control, healthy mice. Our results suggest that serum thymidine kinase levels might be used as a marker to follow the effect of melanoma therapy.
Melanoma Res 1994 Oct
PMID:Thymidine kinase in malignant melanoma. 785 9

To assess the potential of an in vivo, adenovirus-mediated gene therapy approach for the treatment of malignant melanoma, the efficacy of adenovirus-mediated herpes simplex virus thymidine kinase gene (HSV-Ek) transfer and administration of ganciclovir (GCV) was investigated using a nude mouse model. Initially, B16 murine melanoma cells were efficiently transduced in vitro by a recombinant replication-defective adenovirus containing the HSV-tk gene (ADV/RSVtk), and rendered sensitive to cell killing by 10 micrograms/ml GCV. A significant "bystander effect" was observed at low multiplicity of infection in comparison of cell killing to control B16 transduction by adenovirus containing the beta-galactosidase gene (ADV/RSV-beta-gal). In vivo, melanomas established from subcutaneous injection of 4 x 10(5) B16 cells were injected after 14 d with 1 x 10(10) ADV/RSV-tk viral particles. Subsequent treatment for 6 d with GCV resulted in an inhibition of melanoma growth, with an approximately 40-50% reduction in melanoma volume in comparison to controls in repeated experiments. These data demonstrate that adenovirus-mediated gene transfer can function as an efficient delivery system to reduce established tumor burden in vivo. This result may hold significant promise for the development of effective in situ gene therapy for melanoma in humans.
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PMID:Inhibition of melanoma growth by adenoviral-mediated HSV thymidine kinase gene transfer in vivo. 786 Sep 93


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