You are here:
CELL DEATH AND CELL CYCLE PERTURBATION IN THE DEVELOPMENTAL TOXICITY OF THE DEMETHYLATING AGENT 5-AZA-2'-DEOXYCYTIDINE
Citation:
Rogers, J., B. Francis, K. Sulik, A. Alles, E. Massaro, R. Zucker, K. Elstein, M. Rosen, AND N. Chernoff. CELL DEATH AND CELL CYCLE PERTURBATION IN THE DEVELOPMENTAL TOXICITY OF THE DEMETHYLATING AGENT 5-AZA-2'-DEOXYCYTIDINE. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-95/154.
Description:
DNA methylation is a probable mechanism for regulating gene expression, and alterations in methylation may significantly affect embryonic development. e administered the cytidine analog 5-aza-2'-deoxycytidine (DAZA) to pregnant mice to determine its teratogenicity and effects on embryonic cell death and cell cycle. roups of females were dosed i.p. on gestation day 10 with doses of 0.05 to 3 mg/kg DAZA and killed at 4, 8 or 28 hours later. mbryos were stained with Nile blue sulfate (NBS) to identify areas of cell death, and the remaining embryos were frozen for subsequent flow cytometric (FCM) analysis. bservation of litters at term revealed that at dosages > 0.3 mg/kg, cleft palate and hindlimb defects were significantly elevated, and above 0.3 mg/kg fetal weight was significantly decreased. mbryonic mortality did not increase significantly at dosages below 2 mg/kg, but reached 100% at 3 mg/kg. ose-related accumulation of cells in the S and G2/M phases was observed at 4 and 8 hours after maternal dosing. -phase accumulation was the most sensitive indicator of effect, with a dose-related increase in the percentage of hindlimb bud cells in S-phase evident at all dosages at 4 hr after maternal dosing. ecovery was seen by 28 hrs post-dosing at doses lower than 0.3 mg/kg, but cell cycle perturbations persisted at higher dosages. BS staining demonstrated increased cell death in areas of rapid cell division, indicative of replication-associated cytotoxicity, at doses > 0. 1 mg/kg. hese results indicate that the demethylating agent DAZA perturbs embryonal DNA synthesis and results in cell death of rapidly proliferating cells. he observation of cell cycle perturbations and cell death at dosages below those producing frank terata indicate some ability of the embryo to compensate for and/or repair this type of cellular damage.