Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: DrugBank:EXPT01586 (G418)
 2,237 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To determine the potential role of pp60c-src in polyomavirus-transformed cells, we constructed a recombinant plasmid with the mouse metallothionein-I promoter upstream of a src gene in an anti-sense orientation. We cotransfected this plasmid into middle tumor antigen-transformed FR3T3 cells with a plasmid containing the neomycin resistance gene, and G418 resistant colonies were selected. Analysis of these cells for pp60c-src expression revealed that 50 of the 200 cellular clones screened were found to have decreased levels of c-src expression when compared with the parental middle tumor antigen-transformed cells. Three independent clones which transcribed the expected 3.6-kilobase src complementary RNA and had levels of pp60c-src kinase activity comparable to that of normal FR3T3 cells were further analyzed. In the presence of Cd2+, these clones grew significantly slower in monolayer cultures than either the parental transformed cells (FR18-1) or FR18-1 cells transfected with the neomycin resistance gene alone. The morphology of these clones in the presence of Cd2+ was distinct from that of either the parental FR18-1 cells or normal FR3T3 cells. The clones expressing the complementary src RNA were found to form fewer colonies in soft agar, form fewer foci on monolayers of normal rat cells, and form tumors more slowly following injection into syngenic rats when compared with parental FR18-1 cells. The results of these studies suggest that the level of pp60c-src kinase activity affects the growth characteristics and transformation properties of polyoma virus-transformed rat cells.
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PMID:Regulation of pp60c-src synthesis by inducible RNA complementary to c-src mRNA in polyomavirus-transformed rat cells. 243 Dec 89

Expression of herpes simplex virus type 1 (HSV-1) glycoprotein B (gB-1) was obtained in human cells from the gB-1 gene cloned in the episomal replicating vector pBK-1, which contains the origin of replication and early region of the human papovavirus BK. Selective systems for the TK+ phenotype in TK-143B cells and for resistance to G418 in adenovirus 5-transformed 293 cells were used to obtain stable transformants that produced gB-1. While gB-1 expression in 143B cells required induction by HSV-1 early proteins, constitutive gB1 production was observed in 293 cells, where endogenous trans-acting factors probably replace the need for early viral products in the activation of the cloned gB-1 gene. The amount of recombinant gB-1 was comparable to that produced during HSV-1 lytic infection in human cells, due to amplification of the inserted gene in the replicating episomal vector. Expression of gB-1 was induced by cadmium and zinc when the promoter of the mouse metallothionein-I gene was placed upstream of gB1 structural sequences. The inducible system where the gB-1 gene is under the control of its own promoter could be employed to clarify the role of early viral products in induction of gB-1 synthesis. Constitutive expression of gB-1 in human cells could provide useful material for diagnostic purposes and for the preparation of a subunit vaccine against HSV infections.
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PMID:Constitutive expression in human cells of herpes simplex virus type 1 glycoprotein B gene cloned in an episomal eukaryotic vector. 284 17

Metallothionein (MT) proteins are associated with resistance to the toxic effects of heavy metals, chemotherapeutic drugs, and alkylating agents. It has been suggested that MT may mediate both resistance to toxic agents and cellular metal homeostasis. To study the role of MT, we obtained cells expressing a range of MT levels in the absence of heavy metal induction. We cotransfected the eukaryotic G418 resistance vector pSV2neo and mouse MT-1 cDNA in a pBR322 vector into Chinese hamster ovary cells. Of 200 transfected clonal cell populations, five had constitutive MT expression ranging from 31 to 87 ng of MT/mg of protein. All five populations had increased resistance to cadmium but were less resistant to cisplatin than control cells. On the other hand, the level of foreign MT expression correlated well with the degree of cisplatin resistance among the five clones. Resistance to ionizing radiation and growth rate in the absence of drug or radiation treatment were not affected. However, transfected MT gene expression inhibited the ability of Chinese hamster ovary cells to form colonies in the absence of toxic drug treatment (r = -0.95). The perturbation of cisplatin sensitivity after genetic alteration of MT expression indicates a role for MT in drug resistance: however, the fact that transfected MT gene expression decreased rather than increased drug resistance and decreased plating efficiency in the absence of drug implies that the role of MT may not be one of simply "scavenging" toxic molecules. These data suggest a role for MT in homeostatic cellular processes that, when distributed by transfection of active MT genes, have an effect on cellular drug resistance.
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PMID:Altered cisplatin and cadmium resistance and cell survival in Chinese hamster ovary cells expressing mouse metallothionein. 834 Dec 78

Cytochromes P450 catalyze the bioactivation of many carcinogens. In particular, cytochrome P450 1A1 (CYP1A1) catalyzes the conversion of polycyclic aromatic hydrocarbons, such as benzo[a]pyrene, into potent mutagenic agents. Human skin fibroblasts, both DNA repair deficient (xeroderma pigmentosum group A: XPA) and DNA repair normal have been co-transformed with a chimeric gene construct containing human CYP1A1 coding sequences controlled by the cadmium (Cd) ion inducible mouse metallothionein-I promoter and pRSV-NEO, a dominant selectable marker for G418 resistance. Individual G418 resistant colonies were cloned and analyzed for Cd inducible CYP1A1 activity. Six clones of DNA repair deficient cells and five clones of DNA repair proficient cells have been isolated which express Cd inducible CYP1A1. Benzo[a]pyrene-trans-7,8-diol (BPD) is cytotoxic in Cd induced CYP1A1 expressing cells. The cytotoxicity can be inhibited by 10 microM alpha-napthoflavone. Differential cytotoxicity between the DNA repair deficient and proficient CYP1A1 expressing transformants is observed. BPD is cytotoxic to Cd induced CYP1A1 expressing XPA cells at > 10-fold lower doses than it is to Cd induced CYP1A1 expressing DNA repair normal cells. These data indicate that BPD is metabolized to a DNA damaging agent by induced CYP1A1. In contrast, benzo[a]pyrene-trans-7,8-diol-9,10-epoxide added to the media is only slightly more cytotoxic to DNA repair deficient than to proficient cells regardless of CYP1A1 expression. These studies demonstrate the usefulness of the CYP1A1 transformed fibroblasts in examining the cytotoxic effects of benzo[a]pyrene metabolites and suggest the future usefulness in examining the toxic effects of polycyclic aromatic hydrocarbons and other xenobiotics bioactivated by CYP1A1.
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PMID:Expression of human cytochrome P450 1A1 in DNA repair deficient and proficient human fibroblasts stably transformed with an inducible expression vector. 835 49

TIF3 (GenBank Accession Number AF 271072) is identified as a novel cadmium- responsive proto-oncogene. In order to determine whether the antisense TIF3 reverses the oncogenic potential of Cd-transformed BALB/c-3T3 cells or not, a stable expression system of CdCl2-transformed BALB/c-3T3 cells with the expression vector containing TIF3 cDNA in the antisense orientation using calcium phosphate and G418 selection protocols is firstly established. Then, the reversal of the oncogenic potential of these cells is tested by soft agar and nude mouse tumorigenicity assay. The results demonstrated that expression of the antisense TIF3 in the CdCl2-transformed BALB/c-3T3 cells results in reversal of the transformed phenotype of the cells. This is evidenced by a 25%-70% decrease in the number of anchorage-independent colonies growing on soft agar and the significant reduced tumorigenic potential of cells in nude mice compared with the corresponding controls. In addition to a significant delay in the onset of appearance of tumors, a significant reduction in size and a 50.8%-55.1% decrease in weight of the tumors are also observed in the mice injected with the TIF3 antisense expressing cells compared with the corresponding controls. The results indicate that antisense TIF3 mRNA expression reverses its oncogenic potential of Cd-transformed BALB/c-3T3 cells and may have therapeutic potential to cancer induced by cadmium.
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PMID:[Antisense TIF3 reverses the oncogenic potential of CdCl2-transformed BALB/c-3T3 cells]. 1260 33