Diphtheria toxin fused to human interleukin-3 is toxic to blasts from patients with myeloid leukemias.
Leukemic blasts from patients with acute phase chronic myeloid leukemic and refractory acute myeloid leukemia are highly resistant to a number of cytotoxic drugs. To overcome multi-drug resistance, we engineered a diphtheria fusion protein by fusing human interleukin-3 (IL3) to a truncated form of diphtheria toxin (DT) with a (G4S)2 linker (L), expressed and purified the recombinant protein, and tested the cytotoxicity of the DTLIL3 molecule on human leukemias and normal progenitors. The DTLIL3 construct was more cytotoxic to interleukin-3 receptor (IL3R) bearing human myeloid leukemia cell lines than receptor-negative cell lines based on assays of cytotoxicity using thymidine incorporation, growth in semi-solid medium and induction of apoptosis. Exposure of mononuclear cells to 680 pM DTLIL3 for 48 h in culture reduced the number of cells capable of forming colonies in semi-solid medium (colony-forming units leukemia) > or =10-fold in 4/11 (36%) patients with myeloid acute phase chronic myeloid leukemia (CML) and 3/9 (33%) patients with acute myeloid leukemia (AML). Normal myeloid progenitors (colony-forming unit granulocyte-macrophage) from five different donors treated and assayed under identical conditions showed intermediate sensitivity with three- to five-fold reductions in colonies. The sensitivity to DTLIL3 of leukemic progenitors from a number of acute phase CML patients suggests that this agent could have therapeutic potential for some patients with this disease.
Frankel
A E
AE
Department of Cancer Biology, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA.
McCubrey
J A
JA
Miller
M S
MS
Delatte
S
S
Ramage
J
J
Kiser
M
M
Kucera
G L
GL
Alexander
R L
RL
Beran
M
M
Tagge
E P
EP
Kreitman
R J
RJ
Hogge
D E
DE
D004261:DNA Replication / Q000187:drug effects; D004167:Diphtheria Toxin / Q000235:genetics / Q000302:isolation & purification / Q000494:pharmacology*; D019008:Drug Resistance, Neoplasm; D004354:Drug Screening Assays, Antitumor; D006801:Humans; D007377:Interleukin-3 / Q000235:genetics / Q000302:isolation & purification / Q000494:pharmacology*; D007951:Leukemia, Myeloid / Q000473:pathology*; D009363:Neoplasm Proteins / Q000187:drug effects; D014411:Neoplastic Stem Cells / Q000187:drug effects*; D016133:Polymerase Chain Reaction; D016185:Receptors, Interleukin-3 / Q000187:drug effects; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000302:isolation & purification / Q000494:pharmacology; D014407:Tumor Cells, Cultured / Q000187:drug effects; D014410:Tumor Stem Cell Assay
D004167:Diphtheria Toxin; D007377:Interleukin-3; D009363:Neoplasm Proteins; D016185:Receptors, Interleukin-3; D011993:Recombinant Fusion Proteins; C407154:diphtheria toxin-interleukin-3 fusion protein, recombinant