Induction of A:T to G:C transition mutations by 5-(2-chloroethyl)-2'-deoxyuridine (CEDU), an antiviral pyrimidine nucleoside analogue, in the bone marrow of Muta Mouse.
5-(2-chloroethyl)-2'-deoxyuridine (CEDU) is a pyrimidine nucleoside analogue formerly in development for the treatment of herpes simplex virus infections. The compound proved clearly mutagenic in the mouse spot test and exhibited weak activity in the Salmonella reverse mutation test, which led to the termination of the compound's development. In another study, CEDU, administered orally to beta-galactosidase (lacZ) transgenic mice (Muta Mouse) for five days, induced a clear increase in lacZ mutant frequencies in spleen, lung, and bone marrow. In the present follow-up study, we analyzed 32 of those lacZ mutants isolated from the bone marrow of the Muta Mouse animals of the experiments mentioned above, in order to obtain further information on the type of mutations induced by CEDU. CEDU induced a pronounced increase in A:T to G:C transitions. The distribution of A:T to G:C transitions was clearly non-random, showing a bias towards T to C substitutions in the coding DNA strand and a preference to occur in the sequence motif 5'-(G or C)-T-G-3'. Our data support the hypothesis that CEDU, after being phosphorylated, is incorporated into cellular DNA in place of thymidine, which leads to mispairing with guanosine during subsequent DNA replication. As a result, the compound is thought to exert its mutagenicity by inducing mismatches leading to T to C transitions. Our findings point towards a mode of mutagenic action of CEDU that differs fundamentally from that of other antiviral antinucleosides whose clastogenic and recombinogenic activities prevail.
Staedtler
Frank
F
Biomarker Development, Novartis Pharma AG, Klybeckstrasse 41, CH-4002 Basel, Switzerland. frank.staedtler@pharma.novartis.com
Suter
Willi
W
Martus
Hans-Joerg
HJ
D000818:Animals; D000998:Antiviral Agents / Q000737:chemistry / Q000633:toxicity*; D001482:Base Composition; D001483:Base Sequence; D001854:Bone Marrow Cells; D004252:DNA Mutational Analysis; D017931:DNA Primers; D004260:DNA Repair / Q000187:drug effects*; D003857:Deoxyuridine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000633:toxicity*; D007763:Lac Operon / Q000235:genetics*; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics*; D017422:Sequence Analysis, DNA
D000998:Antiviral Agents; D017931:DNA Primers; C047370:5-(2-chloroethyl)-2'-deoxyuridine; D003857:Deoxyuridine