title: Factors modifying 3-aminobenzamide cytotoxicity in normal and repair-deficient human fibroblasts.
abstract: 3-Aminobenzamide (3-AB), an inhibitor of poly(ADP-ribosylation), is lethal to human fibroblasts with damaged DNA. Its cytotoxicity was determined relative to a number of factors including the types of lesions, the kinetics of repair, and the availability of alternative repair systems. A variety of alkylating agents, UV or gamma irradiation, or antimetabolites were used to create DNA lesions. 3-AB enhanced lethality with monofunctional alkylating agents only. Within this class of compounds, methylmethanesulfonate (MMS) treatments made cells more sensitive to 3-AB than did treatment with methylnitrosourea (MNU) or methylnitronitrosoguanidine (MNNG). 3-AB interfered with a dynamic repair process lasting several days, since human fibroblasts remained sensitive to 3-AB for 36-48 hours following MMS treatment. During this same interval, 3-AB caused these cells to arrest in G2 phase. Alkaline elution analysis also revealed that this slow repair was delayed further by 3-AB. Human mutant cells defective in DNA repair differed in their responses to 3-AB. Among mutants sensitive to monofunctional alkylating agents, ataxia telangiectasia cells were slightly more sensitive to 3-AB than control cells, while Huntington's disease cells had a near-normal response. Among UV-sensitive strains, xeroderma pigmentosum variant (XPV) cells were more sensitive to 3-AB after MMS than were XP complementation group A (A) cells, which responded normally. Greater lethality with 3-AB could be dependent on inability of the mutant cells to repair damage by other processes.
mesh_terms: D001549:Benzamides / Q000633:toxicity*; D002110:Caffeine / Q000494:pharmacology; D002453:Cell Cycle / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004260:DNA Repair; D005347:Fibroblasts / Q000187:drug effects*; D006801:Humans; D008297:Male; D008741:Methyl Methanesulfonate / Q000494:pharmacology; D008769:Methylnitronitrosoguanidine / Q000494:pharmacology; D008770:Methylnitrosourea / Q000494:pharmacology; D011064:Poly Adenosine Diphosphate Ribose / Q000378:metabolism; D013997:Time Factors
chemical_list: D001549:Benzamides; D008769:Methylnitronitrosoguanidine; D011064:Poly Adenosine Diphosphate Ribose; D002110:Caffeine; D008770:Methylnitrosourea; C025160:3-aminobenzamide; D008741:Methyl Methanesulfonate