Cytarabine (U-19920A) Cytarabine (U-19920A， Cytarabin, Ara-C, Arabinofuranosyl Cytidine, Cytosine β-D-arabinofuranoside, Cytosine arabinoside, NSC 63878, NSC 287459) is an antimetabolic agent and DNA synthesis inhibitor with IC50 of 16 nM in wild-type C In vitro
Cytarabine (AraC) is phosphorylated into a triphosphate form (Ara-CTP) involving deoxycytidine kinase (dCK), which competes with dCTP for incorporation into DNA, and then blocks DNA synthesis by inhibiting the function of DNA and RNA polymerases. Cytarabine displays a higher growth inhibitory activity towards wild-type CCRF-CEM cells compared to other acute myelogenous leukemia (AML) cells with IC50 of 16 nM. Increasing concentrations of Cytarabine (IC50 of 0.69 μM) results in decreased metabolic activity of sensitive rat leukemic cell line RO/1, and the cell toxity can be highly enhanced by transfection with human wt dCK (IC50 of 0.037 μM) but not the inactive, alternatively spliced dCK forms. Cytarabine apparently induces apoptosis of rat sympathetic neurons at 10 μM, of which 100 μM shows the highest toxicity and kills over 80% of the neurons by 84 hours, involving the release of mitochondrial cytochrome-c and the activation of caspase-3, and the toxicity can be attenuated by p53 knockdown and delayed by bax deletion.
In vivo
Cytarabine is highly effective against acute leukaemias, which causes the characteristic G1/S blockage and synchronization, and increases the survival time for leukaemic Brown Norway rats in a weak dose-related fashion indicating that the use of higher dosages of Cytarabine does not contribute to its antileukaemic effectiveness in man. Cytarabine (250 mg/kg) also causes placental growth retardation and increases placental trophoblastic cells apoptosis in the placental labyrinth zone of the pregnant Slc:Wistar rats, which increases from 3 hour after the treatment and peaks at 6 hour before returning to control levels at 48 hour, with remarkably enhanced p53 protein, p53 trancriptional target genes such as p21, cyclinG1 and fas and caspase-3 activity. Cell Data
