Effect of clofarabine on apoptosis and DNA synthesis in human epithelial colon cancer cells.

Clofarabine, a new-generation purine nucleoside analogue, was thought to work via three mechanisms: incorporation into DNA; induction of apoptosis; and inhibition of ribonucleotide reductase, and showed significant efficacy in pediatric relapsed/refractory acute lymphoblastic leukemia (ALL) and hematologic malignancies in adults. By way of its unique metabolic properties, clofarabine is being explored in lymphoproliferative disorders and solid tumors. In this study, the effect of clofarabine on the DNA synthesis of human colon carcinoma cells (HCT116) was investigated by LigandTracer White which provides a simple and accurate method for investigating the uptake, phosphorylation, retention and DNA incorporation of nucleosides in cells. Clofarabine enters into HCT116 cells in a clearly detectable manner. At 100 nM, the interaction is visible and at 10 microM a high signal is achieved and approaches equilibrium after 1 approximately 2 hours. The thymidine incorporation into the DNA synthesis was rapidly stopped by incubation with 10 microM clofarabine and a 3-fold increase in apoptosis induction in HCT116 cells by clofarabine was detected.