CD44 ligation with A3D8 antibody induces apoptosis in acute myeloid leukemia cells through binding to CD44s and clustering lipid rafts.
CD44 is a cell surface antigen expressed on acute myeloid leukemia cells and is used as a marker to isolate leukemia stem cells. CD44 ligation with the antibody A3D8 has been found to induce apoptosis in human acute promyelocytic leukemia (APL) cells via activation of caspase-8. The mechanism of A3D8-induced caspase-8 activation was studied in APL NB4 cells. A3D8 induces lipid raft clustering which causes Fas aggregation as determined with a confocal microscope. A3D8-induced apoptosis is abrogated by the lipid raft disrupting agent methyl-β-cyclodextrin and the caspase-8 inhibitor Z-IETD-fmk. Western blot analysis reveals that A3D8 binds to the standard form of CD44 (CD44s). HL-60 cells without detectable CD44s protein are not responsive to A3D8-induced apoptosis. SKNO-1 cells containing higher level of CD44s protein are more sensitive to A3D8-induced apoptosis than NB4 cells. These results indicate that A3D8 induces apoptosis in leukemia cells through caspase-8 activation by binding to CD44s protein and inducing lipid raft clustering.
The Division of Hematology/Oncology, Department of Medicine, The Tisch Cancer Institute, Mount Sinai School of Medicine, New York, NY, USA.
Hao
H
Qian
Lijuan
L
Xia
Peixue
P
Ling
Samuel
S
Waxman
Yongkui
Y
Jing
D000911:Antibodies, Monoclonal / Q000276:immunology* / Q000378:metabolism* / Q000494:pharmacology; D017209:Apoptosis / Q000276:immunology*; D053181:Caspase 8 / Q000276:immunology / Q000378:metabolism; D045744:Cell Line, Tumor; D018922:HL-60 Cells; D006801:Humans; D018960:Hyaluronan Receptors / Q000276:immunology* / Q000378:metabolism*; D006820:Hyaluronic Acid / Q000494:pharmacology; D015470:Leukemia, Myeloid, Acute / Q000276:immunology / Q000378:metabolism*; D050356:Lipid Metabolism / Q000276:immunology*; D009842:Oligopeptides / Q000494:pharmacology; D047392:beta-Cyclodextrins / Q000494:pharmacology; D019014:fas Receptor / Q000276:immunology / Q000378:metabolism
D000911:Antibodies, Monoclonal; C497483:CD44 protein, human; D018960:Hyaluronan Receptors; D009842:Oligopeptides; C403753:benzyloxycarbonyl-isoleucyl-glutamyl-threonyl-aspartic acid fluoromethyl ketone; D047392:beta-Cyclodextrins; D019014:fas Receptor; C108732:methyl-beta-cyclodextrin; D006820:Hyaluronic Acid; D053181:Caspase 8