title: [Synergistic cytotoxic effects of chemotherapy in colon tumor cells by simultaneous inhibition of de novo and salvage energy metabolism pathways].
abstract: The success of chemotherapy of colon tumours is currently limited. We have therefore used the human colon tumour cell line HT-29 to evaluate the cytotoxic effects of various drug combinations. Trimidox (3,4,5-trihydroxybenzamidoxime), a recently patented inhibitor of ribonucleotide reductase was combined with cytosinearabinoside (Ara-C) or 2',2'-difluorodeoxycytidine (DFDC) in order to inhibit both pyrimidine de novo and salvage pathways. Synergistic cytotoxic effects were observed. When HT-29 cells were sequentially treated with trimidox (20 microM for 24 h) and Ara-C (2 microM for 2 h), colony numbers decreased to 71% of the value calculated for additive cytotoxicity. When cells were simultaneously treated with trimidox (10 microM and 15 microM) and DFDC (0.2 nM), synergistic inhibition of colony formation was likewise noted (colony numbers decreased to values as low as 73% or 71% of the values calculated for additive cytotoxicity). On the other hand, we combined tiazofurin, an inhibitor of the guanylate de novo pathway, with allopurinol, which inhibits the guanylate salvage pathway by increasing intracellular hypoxanthine concentrations, leading to inhibition of the enzyme hypoxanthine-guanine phosphoribosyltransferase (HGPRT). Synergistic cytotoxic effects were observed under these conditions too. When cells were treated with 10 microM tiazofurin and 400 microM or 800 microM allopurinol the number of colonies decreased to 69% and 27%, respectively, of the values calculated for additive effects. Our data suggest these drug combinations to be promising options in the treatment of human colon cancer.
authors.affiliation: Institut für Medizinische Chemie der Universität Wien.
authors.forename: T
authors.initials: T
authors.lastname: Szekeres
authors.forename: M
authors.initials: M
authors.lastname: Fritzer
authors.forename: H J
authors.initials: HJ
authors.lastname: Schön
authors.forename: G
authors.initials: G
authors.lastname: Findenig
authors.forename: C
authors.initials: C
authors.lastname: Lhotka
mesh_terms: D000493:Allopurinol / Q000494:pharmacology; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D001550:Benzamidines / Q000494:pharmacology*; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects*; D003110:Colonic Neoplasms / Q000473:pathology*; D003561:Cytarabine / Q000494:pharmacology*; D003841:Deoxycytidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D006801:Humans; D019271:Hypoxanthine; D007042:Hypoxanthines / Q000494:pharmacology; D012254:Ribavirin / Q000031:analogs & derivatives / Q000494:pharmacology; D012264:Ribonucleotide Reductases / Q000037:antagonists & inhibitors*; D014407:Tumor Cells, Cultured / Q000187:drug effects* / Q000473:pathology; D014410:Tumor Stem Cell Assay; D000093542:Gemcitabine
chemical_list: C074761:3,4,5-trihydroxybenzamidoxime; D000964:Antimetabolites, Antineoplastic; D001550:Benzamidines; D007042:Hypoxanthines; D003561:Cytarabine; D003841:Deoxycytidine; D019271:Hypoxanthine; D012254:Ribavirin; D000493:Allopurinol; D012264:Ribonucleotide Reductases; C033706:tiazofurin; D000093542:Gemcitabine
vernacular_title: Synergistische zytotoxische Effekte einer Chemotherapie an Kolontumorzellen durch gleichzeitige Hemmung von de novo und salvage Stoffwechselwegen.