In vitro activity: Decitabine inhibits cell growth in a dose and time-dependent manner with IC50 of approximately 438 nM and 43.8 nM for 72 hours and 96 hours exposure in HL-60 and KG1a leukemic cells, respectively. A recent study shows that Decitabine exhibits high anti-proliferative and pro-apoptotic activity against anaplastic large cell lymphoma (ALCL), and inhibits [3H]–thymidine uptake in KARPAS-299 cells with EC50 of 0.49 μM.

Kinase Assay: The rate of DNA synthesis is measured by the incorporation of radioactive thymidine into DNA. HL-60 and KG1a cells are suspended in 2 mL RPMI medium containing 10% fetal serum in 6-well (35 mm diameter) dishes and incubated with different concentrations of corresponding drugs for 48 hours (drugs are added simultaneously). At 48 hours, 0.5 μCi [3H] thymidine (6.7 Ci/mmol) is added to each well and incubated for an additional 24 hours. The cells are placed on GF/C glass fiber filters (2.4 cm diameter), washed with cold 0.9% NaCl, 5% cold trichloroacetic acid and ethanol. The filters containing the DNA are then dried, placed in EcoLite scintillation liquid (ICN) and the radioactivity measured using Beckman LS 6000IC scintillation counter. The IC50 is defined as the concentration of drug that inhibits 50% of the DNA synthesis of the leukemic cell lines from the dose–response curve.

Cell Assay: For the growth inhibition assay, cells in log phase are placed in 5 mL of medium. Different concentrations of Decitabine are added to the medium simultaneously. Cell counts are performed at the indicated times using a model ZM Coulter Counter. The concentration that produces 50% inhibition of growth (IC50) is determined from the growth curves of the drug treated leukemic cell line (HL-60 and KG1a).

Leuk Res. 2003 May;27(5):437-44; Biochimie. 2012 Nov;94(11):2297-307.