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Mutation Research May 19796 platinum (Pt) compounds were compared in suspension cultured Chinese hamster ovary (CHO-S) cells with respect to their inhibition of growth, their reduction of cloning...
6 platinum (Pt) compounds were compared in suspension cultured Chinese hamster ovary (CHO-S) cells with respect to their inhibition of growth, their reduction of cloning efficiency, and their induction of mutants resistant to 200 microM (30 micrograms/ml) 8-azaguanine (8-AG) and 3 mM ouabain (OUA), respectively. The toxicity of these compounds can be ranked by the medium concentrations which decrease suspension growth/or cloning efficiency by 50%: cis-Pt(NH3)2-Cl2 (0.9/1.5 microM) greater than Pt(SO4)2 + methylcobalamin (MeB-12) methylation product (20/10 microM) greater than K2PtCl4 (32/50 microM) = K2PtCl6 (34/50 microM) = MePtCl2-3 (60/50 microM) greater than Pt(SO4)2 (66/105 microM). Following 20 h exposures to concentrations which resulted in relative survivals of 80-2%, none of the foregoing compounds increased consistently the frequency of OUA(R) mutants above the spontaneous frequency (6.0 x 10(-6)). Parallel treatments with 800 microM (100 micrograms/ml) ethyl methanesulfonate (EMS) increased the OUA(R) mutant frequency 10--12-fold. Using 8-AG for mutant selection, dose-dependent increases of 5--7-fold above the spontaneous frequency (3--8 x 10(-5) were obtained with cis-Pt(NH3)2Cl2, Pt(S04)2, and the product from Pt(SO4)2 + MeB-12. Identical 20 h exposures to varying amounts of K2PtCl4, K2PtCl6, and MePtCl2-3 did not induce 8-AG(R) mutants. Optimal detection of Pt-induced 8-AG(R) mutants required 7 post-treatments, expression doublings in suspension culture. Under our selection conditions 8/8 spontaneous and 24/24 Pt-induced 8-AG(R) variants contained reduced hypoxanthine-guanine phosphoribosyl transferase (HGPRT) specific activities (means ranging from 3 to 11% of the parental CHO-S cells). When compared from linear plots of the 8-Ag(r) frequency against the initial medium concentration, cis-Pt(NH3)2Cl2 is 134 times and Pt(SO4)2 si 3.5 times more mutagenic than EMS. However, on a cell-survival basis EMS is 8--10-fold more mutagenic than these two Pt-compounds. 6-Thioguanine (10 microM) can be substituted for 8-AG to assay mutant induction by cis-Pt(NH3)2Cl2 and Pt(SO4)2 in CHO-S cells. The sensitivity of the CHO-S HGPRT locus for detecting mutagenesis by Pt complexes can be increased several fold by continuous subculture in the presence of these agents for 10--25 population doublings. By this procedure K2PtCl6 is seen to be weakly mutagenic and 20 microM Pt(SO4)2 produces 8-AG(R) mutants at frequencies requiring 7--8-fold higher concentrations when a fixed 20 h exposure is used.
Topics: Animals; Azaguanine; Cell Line; Cricetinae; Drug Resistance; Mutagens; Mutation; Platinum
PubMed: 460295
DOI: 10.1016/0165-1218(79)90100-9 -
Journal of Cellular Physiology Oct 1976In this study the resistance of a number of lines of Chinese hamster ovary cells to azaguanine is examined. Those which are drug resistant by virtue of a deficiency of...
In this study the resistance of a number of lines of Chinese hamster ovary cells to azaguanine is examined. Those which are drug resistant by virtue of a deficiency of hypoxanthine-guanine phosphoribosyltransferase (HPRT) fail to take up any exogenous hypoxanthine or azaguanine. A second class of drug resistant cells which grow in the reverse selective HAT medium and have levels of HPRT in the range of the wild type parent line take up these purines at lower rates than the nonresistant cells and incorporate smaller amounts of them into trichloracetic acidinsoluble constituents. The results suggest that their basis for resistance resides in lowered incorporation of azaguanine into DNA and RNA, possibly due to a mofified HPRT molecule which accepts hypoxanthine, but not azaguanine as a substrate.
Topics: Amino Acids; Aminopterin; Azaguanine; Cell Line; Drug Resistance; Guanine; Hypoxanthine Phosphoribosyltransferase; Hypoxanthines; Inosine Nucleotides; Protein Biosynthesis; Uridine
PubMed: 972164
DOI: 10.1002/jcp.1040890204 -
Cancer Chemotherapy Reports Jul 1966
Topics: Animals; Azaguanine; Brain Neoplasms; Cats; Dogs; Glioma; Humans; Injections, Spinal; Perfusion
PubMed: 5952508
DOI: No ID Found -
Proceedings of the Society For... Jul 1974
Topics: Animals; Azaguanine; Enzyme Induction; Estradiol; Female; Glucosephosphate Dehydrogenase; Male; NADP; Rats; Time Factors; Uterus
PubMed: 4152244
DOI: 10.3181/00379727-146-38184 -
Genetics Jun 1969
Topics: Animals; Azaguanine; Cell Line; Clone Cells; Cricetinae; Culture Techniques; Genetics; Glutamine; Hybridization, Genetic; Hypoxanthines; Karyotyping; Male; Mutation; Selection, Genetic; Transferases
PubMed: 5392645
DOI: 10.1093/genetics/62.2.359 -
Mutation Research May 1975The ability of the carcinogen, N-acetoxy-2-acetylaminofluorene (N-AcO-AAF), to induce mutations to azaguanine resistance in diploid human cells was quantitatively...
The ability of the carcinogen, N-acetoxy-2-acetylaminofluorene (N-AcO-AAF), to induce mutations to azaguanine resistance in diploid human cells was quantitatively investigated and shown to be dose-dependent. The 8-azaguanine (AG) resistance was shown to be heritable in the absence of mutagen or selective agent and the cells of the mutant clones were shown to retain normal sensitivity to N-AcO-AFF.
Topics: Acetoxyacetylaminofluorene; Azaguanine; Cell Survival; Cells, Cultured; Clone Cells; Culture Media; Diploidy; Dose-Response Relationship, Drug; Drug Resistance; Fibroblasts; Fluorenes; Humans; In Vitro Techniques; Mutation
PubMed: 1134509
DOI: 10.1016/0027-5107(75)90105-0 -
The Journal of Biological Chemistry Jul 1954
Topics: Azaguanine; Glycosides; Guanine
PubMed: 13192085
DOI: No ID Found -
Gan Sep 1955
Topics: Animals; Azaguanine; Biomedical Research; Guanine; Neoplasms
PubMed: 13262474
DOI: No ID Found -
Acta Crystallographica. Section D,... Jul 2005Purine nucleoside phosphorylase (PNP) is a key enzyme in the purine-salvage pathway, which allows cells to utilize preformed bases and nucleosides in order to synthesize...
Purine nucleoside phosphorylase (PNP) is a key enzyme in the purine-salvage pathway, which allows cells to utilize preformed bases and nucleosides in order to synthesize nucleotides. PNP is specific for purine nucleosides in the beta-configuration and exhibits a strong preference for purines containing a 6-keto group and ribosyl-containing nucleosides relative to the corresponding analogues. PNP was crystallized in complex with ligands and data collection was performed using synchrotron radiation. This work reports the structure of human PNP in complex with guanosine (at 2.80 A resolution), 3'-deoxyguanosine (at 2.86 A resolution) and 8-azaguanine (at 2.85 A resolution). These structures were compared with the PNP-guanine, PNP-inosine and PNP-immucillin-H complexes solved previously.
Topics: Azaguanine; Binding Sites; Crystallography, X-Ray; Guanine; Guanosine; Humans; Inosine; Ligands; Purine Nucleosides; Purine-Nucleoside Phosphorylase; Pyrimidinones; Pyrroles
PubMed: 15983407
DOI: 10.1107/S0907444905005421 -
Nature Aug 1959
Topics: Animals; Azaguanine; Biochemical Phenomena; Blastoderm; Chickens; Hemoglobins; Purines
PubMed: 14428007
DOI: 10.1038/184376a0