Induction of apoptotic cell death in chronic lymphocytic leukemia by 2-chloro-2'-deoxyadenosine and 9-beta-D-arabinosyl-2-fluoroadenine.
2-Chloro-2'-deoxyadenosine (CldAdo) and 9-beta-D-arabinosyl-2-fluoroadenine (F-ara-A) have shown marked activity in the treatment of indolent lymphoid malignancies. Based on the susceptibility of various lymphocyte populations to apoptosis, we investigated whether CldAdo or F-ara-A would induce this process in lymphocytes from patients with chronic lymphocytic leukemia (CLL). In vitro exposure of leukemic lymphocytes to CldAdo or F-ara-A for 24 to 72 hours elicited features of apoptosis visible by light and electron microscopy. Analysis of DNA integrity showed DNA cleavage into nucleosomal-sized multimers. Using a quantitative assay, drug-induced DNA fragmentation was both time and dose dependent. Inhibition of active macromolecular synthesis did not prevent drug-induced fragmentation; however, both drug-induced and spontaneous DNA fragmentation were prevented by intracellular calcium chelation. In vitro culture with phorbol ester generally decreased drug-induced DNA cleavage. After prolonged incubation, CLL cells exhibited spontaneous cleavage; albeit, at significantly lower rates than drug-treated cells. Heterogeneity was observed for spontaneous and drug-induced DNA fragmentation and was significantly lower in B-leukemic cells obtained from patients with high-risk and refractory disease. We conclude that CldAdo and F-ara-A are potent inducers of apoptotic death in CLL and that this feature correlates with the disease status.
Robertson
L E
LE
Department of Hematology, University of Texas, M.D. Anderson Cancer Center, Houston 77030.
Chubb
S
S
Meyn
R E
RE
Story
M
M
Ford
R
R
Hittelman
W N
WN
Plunkett
W
W
D000255:Adenosine Triphosphate / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects*; D017338:Cladribine / Q000494:pharmacology*; D003513:Cycloheximide / Q000494:pharmacology; D004273:DNA, Neoplasm / Q000378:metabolism; D003609:Dactinomycin / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D006160:Guanosine Triphosphate / Q000378:metabolism; D006801:Humans; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000473:pathology*; D008214:Lymphocytes / Q000473:pathology; D008854:Microscopy, Electron; D011691:Puromycin / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D014544:Uridine Triphosphate / Q000378:metabolism; D014740:Vidarabine / Q000031:analogs & derivatives* / Q000494:pharmacology
D004273:DNA, Neoplasm; D003609:Dactinomycin; D017338:Cladribine; D011691:Puromycin; D004533:Egtazic Acid; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate; D003513:Cycloheximide; D014740:Vidarabine; D013755:Tetradecanoylphorbol Acetate; C024352:fludarabine; D014544:Uridine Triphosphate