Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.5.4.17 (adenosine deaminase)
 5,206 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

2'-Deoxycoformycin (2'-dCF), a potent inhibitor of adenosine deaminase, was tested in combination with 9-beta-D-arabinofuranosyladenine (ara-A) and 9-beta-D-arabinofuranosyladenine 5'-formate for cytotoxic activity against mouse leukemia L1210 in culture. 2'-dCF, which alone had no activity, significantly enhanced cytostatic and cytotoxic activities of ara-A and its more soluble derivative, 9-beta-D-arabinofuranosyladenine 5'-formate; the latter 2 agents, when tested at equimolar concentrations, were equivalent in their effects on proliferation and viability. The therapeutic response of mice bearing the in vitro line of L1210 cells (L1210/C2) to combination therapy with 2'-dCF and 9-beta-D-arabinofuranosyladenine 5'-phosphate was comparable to that reported elsewhere for therapy of mice bearing the parent in vivo line. Continuous exposure of cultured L1210 cells to ara-A and 2'-dCF induced a prolonged period of unbalanced growth, characterized by inhibition of proliferation and DNA synthesis while RNA and protein synthesis continued; exposure periods in excess of a single population doubling were required to achieve significant cell kill. Potentiation of ara-A activity against the relatively insensitive mouse leukemia L1210 was attributed to increased stability of ara-A resulting from 2'-dCF inhibition of adenosine deaminase.
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PMID:Enhancement of 9-beta-d-arabinofuranosyladenine cytotoxicity to mouse leukemia L1210 in vitro by 2'-deoxycoformycin. 94 95

Cultured mouse leukemia L1210 cells express the nucleoside-specific membrane transport processes designated es, ei, and cif. The es and ei processes are equilibrative, but may be distinguished by the high sensitivity of the former to 6-[(4-nitrobenzyl)thio]-9-beta-D-ribofuranosylpurine (NBMPR); the cif process is mediated by a Na+/nucleoside cotransporter of low sensitivity to NBMPR. Cells of an ei-deficient clonal line, L1210/MC5-1, were mutagenized, and clones were selected in soft agar medium that contained (i) NBMPR (an inhibitor of es processes), (ii) erythro-9-(2-hydorxy-3-nonyl)adenine (an inhibitor of adenosine deaminase), and (iii) arabinofuranosyladenine (a cytotoxic substrate for the three nucleotide transporters). The selection medium did not allow es activity and selected against cells that expressed the Na(+)-linked cif process. Cells of the L1210/B23.1 clonal isolate were deficient in cif transport activity, and inward fluxes of formycin B, a poorly metabolized analog of inosine, were virtually abolished by NBMPR in these cells. In the mutant cells, nonisotopic formycin B behaved as a countertransport substrate during influx of [3H]formycin B, and inward fluxes of the latter were competitively inhibited by purine and pyrimidine nucleosides. The transport behavior of L1210/B23.1 cells indicates that (i) the mutation/selection procedure impaired or deleted the Na(+)-linked cif process and (ii) es nucleoside transport activity is expressed in the mutant cells.
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PMID:L1210/B23.1 cells express equilibrative, inhibitor-sensitive nucleoside transport activity and lack two parental nucleoside transport activities. 151 37

2'-Chloropentostatin is a new inhibitor of adenosine deaminase isolated from the fermentation broth of an unidentified actinomycete, ATCC 39365. It contains the aglycone of coformycin, i.e. 3,6,7,8-tetrahydroimidazo[4,5-d][1,3]diazepin-8-o1, coupled to the unusual carbohydrate, 2'-chloro-2'-deoxyribose. 2'-Chloropentostatin is a slightly weaker inhibitor of rat and human adenosine deaminases than coformycin, and considerably weaker than pentostatin. Unlike pentostatin, which appears to undergo a two-stage interaction with adenosine deaminase, 2'-chloropentostatin forms a single enzyme-inhibitor complex. The enzyme-inhibitor complex between adenosine deaminase and 2'-chloropentostatin was much more rapidly dissociable than the complex with pentostatin. The complex between adenosine deaminase and 2'-chloropentostatin dissociated with a half-life of approximately 3 hr, compared with 68 hr for the complex between adenosine deaminase and pentostatin. 2'-Chloropentostatin, at concentrations up to 10 micromolar, did not cause significant inhibition of growth of WI-L2 human B-cell lymphoblasts, or of CCRF-CEM human T-cell lymphoblasts in culture. However, it greatly potentiated the inhibitory potency of adenosine, 2'-deoxyadenosine, or arabinosyladenine towards these cell lines. This potentiating effect was equipotent for 2'-chloropentostatin and pentostatin. T-cells (CCRF-CEM) were much more sensitive to the inhibitory effect of combinations of adenosine or 2'-deoxyadenosine with 2'-chloropentostatin or pentostatin than were B-cells (WI-L2). Pentostatin and 2'-chloropentostatin had no significant antitumor activity against mouse leukemia L1210 in vivo. However, these adenosine deaminase inhibitors, at nontoxic doses, greatly potentiated the antitumor activity of ara-A 5'-phosphate. 2'-Chloropentostatin was somewhat more active in this regard than was pentostatin.
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PMID:The biochemical pharmacology of (2'-R)-chloropentostatin, a novel inhibitor of adenosine deaminase. 243 5

9-beta-D-Arabinofuranosyl-2-fluoroadenine (2-F-ara-A), a derivative of 9-beta-D-arabinofuranosyladenine (ara-A) that is resistant to deamination, selectively inhibits DNA synthesis and has activity against mouse leukemia L1210 comparable to that of ara-A plus the adenosine deaminase inhibitor, 2'-deoxycoformycin. To determine if these two nucleosides have similar modes of action, comparisons were made of their effects and those of their triphosphates on enzymes known to be inhibited by ara-A or 9-beta-D-arabinofuranosyladenine 5'-triphosphate. 9-beta-D-Arabinofuranosyl-2-fluoroadenine 5'-triphosphate was more effective than 9-beta-D-arabinofuranosyladenine 5'-triphosphate in inhibiting the reduction of adenosine 5'-diphosphate and cytidine 5'-diphosphate by ribonucleotide reductase from HEp-2 cells or L1210 cells. DNA polymerase alpha from L1210 cells was equally sensitive to 9-beta-D-arabinofuranosyl-2-fluoroadenine 5'-triphosphate and 9-beta-D-arabinofuranosyladenine 5'-triphosphate, and DNA polymerase beta from L1210 cells was much less sensitive to both triphosphates. S-Adenosylhomocysteine hydrolase from L1210 cells was inactivated by 2-F-ara-A and ara-A, but higher concentrations of the fluoro derivative were required. These results are consistent with 2-F-ara-A and ara-A inhibition of DNA synthesis by inhibition of ribonucleotide reductase and DNA polymerase alpha.
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PMID:Comparison of the actions of 9-beta-D-arabinofuranosyl-2-fluoroadenine and 9-beta-D-arabinofuranosyladenine on target enzymes from mouse tumor cells. 704 80