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)

We have analyzed the effect of the poly(ADP-ribose) synthesis inhibitor 3 aminobenzamide (3AB) on de novo and methyl methanesulfonate (MMS) and gamma irradiation enhancement of viral transformation of a cloned rat embryo fibroblast cell line, CREF, by a cold-sensitive host-range mutant of type 5 adenovirus, H5hr1. Additionally, we have evaluated the effect of 3AB on the transformation of CREF cells following transfection with a gene conferring resistance to hygromycin (hygr) or the neomycin analogue G418 (neor) in combination with a cloned type 5 adenovirus E1A transforming gene (Ad5 E1A) or the Ha-ras (T24) oncogene. 3AB induced a dose- and time-dependent increase in the level of de novo MMS-enhanced and gamma irradiation-enhanced transformation of CREF cells by H5hr1, whereas it did not induce morphological transformation in uninfected control, MMS-pretreated, or gamma irradiation-pretreated CREF cells. Temporal kinetic studies indicated that 3AB was most effective in enhancing de novo and MMS-enhanced and gamma irradiation-enhanced viral transformation when applied early after viral and carcinogen plus viral infection and when present for extended time periods (4-5 wk). 3AB also increased the frequency of resistant colonies following transfection with several cloned genes, including hygr, neor, and protein kinase C (which also contained a neor gene), and the frequency of morphological transformation of CREF cells following cotransfection with a hygr gene and an Ad5 E1A or an activated Ha-ras (T24) gene. In contrast, 3AB exerted the opposite effect, i.e., an inhibitory effect, when applied to NIH 3T3 cells transfected with a hygr or neor gene, alone or in combination with a T24 gene. The ability of 3AB to enhance the frequency of transformation of CREF cells was not associated with a selective effect on the growth of H5hr1-transformed CREF cells in monolayer or agar culture. Similarly, 3AB did not alter the percentage of MMS- or gamma irradiated-pretreated H5hr1-infected cells retaining free Ad5 DNA or the random pattern or quantity of viral DNA integration in control or carcinogen-treated H5hr1-transformed cells. These results suggest that cellular processes regulated by the nuclear enzyme ADPRT, or additional processes modified by 3AB, may be important mediators of stable transformation induced by transfected DNA and both de novo and carcinogen-enhanced viral transformation of specific target cells.
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PMID:Enhancement of viral and DNA mediated transformation of cloned rat embryo fibroblast cells by 3-aminobenzamide. 212 9

The frequency of sister-chromatid exchange (SCE) was studied in Chinese hamster ovary (CHO) cell lines with stable insertions of the vector pIII-14gpt which contains 2 truncated neomycin resistance (neo) gene fragments. Recombination between regions of homology in the 2 fragments can restore a functional neo gene and make the cell resistant to the antibiotic G418, a neomycin analogue. Unequal SCE would be one of several possible mechanisms for this event. The observed spontaneous rate of formation of G418-resistant subclones was approximately 6.4 x 10(-6) per cell per generation, as compared to the estimated spontaneous frequency of 3 SCE per cell per generation. Given this SCE frequency, the probability of an SCE occurring in a target site of about 1600 bp (the distance separating the homologous regions in the neo fragments) would be about 8 x 10(-7) per cell per generation, or approximately one tenth of the estimated rate of recombination. Treatment of the cells with methyl methanesulfonate (MMS, 50 x 10(-6) M) induced about 80-90 SCE per cell, corresponding to a probability of 2 x 10(-5) SCE per 1600-bp target per cell. In the same cell culture, MMS treatment induced 4-8 x 10(-4) recombination events per cell giving rise to G418 resistance. Cells treated with HN2 (up to 4 x 10(-6) M) showed a significant increase in SCEs, but no change in the frequency of G418-resistant revertants. These results suggest that the 2 pathways leading to SCE and recombination respectively are uncoupled, and only a small fraction of the recombination events, if any, are due to unequal SCE in this system.
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PMID:Unequal SCE is a rare event in homologous recombination between duplicated neo gene fragments in CHO cells. 230 86

Homologous recombination between 2 truncated neo genes stably integrated in the genome of Chinese hamster ovary (CHO) cells was studied. A vector containing a functional gpt gene and 2 tandemly arranged G418 resistance (neo) gene fragments with about 400 bp of sequence homology was transfected into CHO cells. Clonal cell lines were established from transfected cultures and the spontaneous frequency of G418-resistant revertants was found to range between 1 x 10(-4) and 5 x 10(-4). The ability of the alkylating agents MMS and HN2 to induce recombination of the transfected neo genes was studied in 2 of the cell lines. After treatment with MMS at doses that reduced survival to 10% of the control these cell lines showed a dose-dependent increase in the frequency of G418-resistant revertants. No effect was observed after treatment with HN2. All G418-resistant subclones contained a new restriction fragment indicating that a whole neo gene had been formed by rearrangement in pairs of truncated neo genes. Hence, this system can be used to study molecular mechanisms and chemical inducibility of homologous recombination in mammalian cells.
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PMID:Induced recombination between duplicated neo genes stably integrated in the genome of CHO cells. 253 88

Poly(ADP-ribose)polymerase (PARP) is a DNA-binding protein that is activated upon induction of DNA breaks and supposed to play a role in DNA repair. To elucidate the effect of overexpression of PARP on the resistance of cells to mutagens, Chinese hamster ovary cells (both the line CHO-9 and the mutagen-hypersensitive derivative 27-1) were transfected with the human PARP cDNA along with pSV2neo. Treatment of the transfected cell population with a high dose of MNNG and selection with G418 gave rise to a significant increase of neo+ clones, as compared to the control transfection with pSV2neo + salmon sperm DNA. The frequency of survivors in these mass culture experiments was lower, however, than after transfection with the bacterial ada gene encoding the DNA repair protein O6-alkylguanine-DNA alkyltransferase. Thus transfection of PARP cDNA in CHO cells is only weakly effective in inducing alkylation resistance. This was confirmed by analyzing the mutagen resistance of individual PARP transfectant clones derived from CHO-9 and 27-1 cells that expressed increased levels of PARP mRNA, protein and PARP activity. These strains were slightly more resistant to the toxic effect of MMS and showed a reduced frequency of MMS-induced chromosomal aberrations. CHO-9-PARP transfectants also gained resistance to UV. From these data we conclude that, in CHO cells, PARP is limiting in handling critical lesions during the repair process and that increase of the amount of PARP protein can elicit some protection against genotoxic effects of mutagens.
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PMID:Effect of transfection of human poly(ADP-ribose)polymerase in Chinese hamster cells on mutagen resistance. 751 39