Expression of interleukin-3 receptor subunits on defined subpopulations of acute myeloid leukemia blasts predicts the cytotoxicity of diphtheria toxin interleukin-3 fusion protein against malignant progenitors that engraft in immunodeficient mice.
The interleukin-3 receptor (IL-3R) subunits are overexpressed on acute myeloid leukemia (AML) blasts compared with normal hematopoietic cells and are thus potential targets for novel therapeutic agents. Both fluorescence-activated cell sorter (FACS) analysis and quantitative real-time reverse transcription-polymerase chain reaction (QRT-PCR) were used to quantify expression of the IL-3Ralpha and beta(c) subunits on AML cells. QRT-PCR for both subunits was most predictive of killing of AML colony-forming cells (AML-CFCs) by diphtheria toxin-IL-3 fusion protein (DT(388)IL3). Among 19 patient samples, the relative level of the IL-3Ralpha was higher than the IL-3Rbeta(c) and highest in CD34(+)CD38(-)CD71(-) cells, enriched for candidate leukemia stem cells, compared with cell fractions depleted of such progenitors. Overall, the amount of IL-3Rbeta(c) subunit did not vary among sorted subpopulations. However, expression of both subunits varied by more than 10-fold among different AML samples for all subpopulations studied. The level of IL-3Rbeta(c) expression versus glyceraldehyde-3-phosphate dehydrogenase (GAPDH) (set at 1000) ranged from 0.14 to 13.56 in CD34(+)CD38(-)CD71(-) cells from different samples; this value was correlated (r = .76, P = .05) with the ability of DT(388)IL3 to kill AML progenitors that engraft in beta(2)-microglobin-deficient nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice (n = 7). Thus, quantification of IL-3R subunit expression on AML blasts predicts the effectiveness IL-3R-targeted therapy in killing primitive leukemic progenitors.
Yalcintepe
Leman
L
Terry Fox Laboratory, BC Cancer Agency, 675 West 10th Ave, Vancouver, BC V5Z 1L3 Canada.
Frankel
Arthur E
AE
Hogge
Donna E
DE
D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage*; D001752:Blast Crisis / Q000473:pathology; D053648:Cytokine Receptor Common beta Subunit / Q000032:analysis; D004167:Diphtheria Toxin / Q000627:therapeutic use*; D016503:Drug Delivery Systems; D005260:Female; D006801:Humans; D016130:Immunophenotyping; D053650:Interleukin-3 Receptor alpha Subunit / Q000032:analysis; D007951:Leukemia, Myeloid / Q000175:diagnosis / Q000188:drug therapy* / Q000473:pathology*; D008297:Male; D051379:Mice; D016513:Mice, SCID; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000032:analysis; D009374:Neoplasms, Experimental; D014411:Neoplastic Stem Cells / Q000637:transplantation; D011237:Predictive Value of Tests; D011379:Prognosis; D016185:Receptors, Interleukin-3 / Q000032:analysis*; D011993:Recombinant Fusion Proteins / Q000627:therapeutic use
D000970:Antineoplastic Agents; D053648:Cytokine Receptor Common beta Subunit; D004167:Diphtheria Toxin; C115022:IL3RA protein, human; D053650:Interleukin-3 Receptor alpha Subunit; D009363:Neoplasm Proteins; D016185:Receptors, Interleukin-3; D011993:Recombinant Fusion Proteins