title: Correlation of apoptotic potential of simple oxiranes with cytotoxicity.
abstract: The measurement of primary DNA damage caused by oxirane chemicals can be confounded by apoptotic-generated DNA autolysis. The apoptogenic potential of oxiranes requires knowledge of the relationship between the apoptotic threshold dose and cytotoxic dose for interpretation of DNA damage assays. This research determined the relationship between cytotoxic and apoptotic doses for seven simple oxiranes of varying structure. This relationship between cytotoxic and apoptotic thresholds was determined simultaneously in in vitro cell culture. L929 cells in log-phase growth were exposed to the oxiranes for 24 h in 25 cm(2) and then assayed fluorometrically in 96-well plates for Caspase 3. Viability was assessed using Trypan Blue exclusion and loss of Caspase 3 activity. Ranked apoptotic potency was: diepoxybutane (DEB)>styrene oxide (SO)>phenyl glycidyl ether (PGE)>epichlorhydrin (EPI)>glycidol (GLY)>epoxybutane (EB)>epoxycyclohexane (ECH). Relative cytotoxicity was significantly correlated (r(s)=0.86, p=0.02) with potencies: DEB>EPI>PGE>SO>GLY>EB>ECH. These structurally-diverse, simple oxiranes were all capable of inducing apoptosis at doses several-fold below their cytotoxic concentrations. Difunctionality and aromaticity were key predictors of potency for both. Caspase 3 activity was an accurate indicator of necrosis which correlated with Trypan Blue results.
authors.affiliation: School of Dentistry, Department of Oral Biology, University of Missouri-Kansas City, 650 E. 25th Kansas City, MO 64108, USA. brockmannw@umkc.edu
authors.forename: W G
authors.initials: WG
authors.lastname: Brockmann
authors.forename: E L
authors.initials: EL
authors.lastname: Kostoryz
authors.forename: J D
authors.initials: JD
authors.lastname: Eick
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002452:Cell Count; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D004249:DNA Damage / Q000187:drug effects*; D003609:Dactinomycin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005027:Ethylene Oxide / Q000633:toxicity*; D005047:Etoposide / Q000494:pharmacology; D005347:Fibroblasts / Q000187:drug effects; D051379:Mice; D009842:Oligopeptides / Q000494:pharmacology
chemical_list: D009842:Oligopeptides; C110772:benzoylcarbonyl-aspartyl-glutamyl-valyl-aspartyl-fluoromethyl ketone; D003609:Dactinomycin; D005047:Etoposide; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases; D005027:Ethylene Oxide