The synthetic heat shock protein 90 (Hsp90) inhibitor EC141 induces degradation of Bcr-Abl p190 protein and apoptosis of Ph-positive acute lymphoblastic leukemia cells.
The prognosis of patients with Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL) is poor. Chemotherapy is rarely curative and tyrosine kinase inhibitors (TKIs) induce only transient responses. Heat shock protein 90 (Hsp90) is a chaperone protein that is important in signal transduction, cell cycle control, and transcription regulation in both normal and leukemia cells. In the current study, we tested the growth inhibitory and apoptotic effects of a novel Hsp90 inhibitor, EC141 on the Ph+ ALL lines Z-119, Z-181, and Z-33, as well as primary bone marrow-derived blasts from patients with newly diagnosed Ph+ ALL. We found that EC141 inhibited the growth of Ph+ ALL cells in a concentration-dependent manner with IC(50) ranged from 1 to 10 nM. EC141 also inhibited the proliferation of primary bone marrow-derived blasts using the ALL blast colony assay. EC141 down-regulated Hsp90 and up-regulated Hsp70 protein levels, inhibited CrkL phosphorylation, and induced degradation of Bcr-Abl p190 protein through ubiquitin-dependent proteasomal pathway. Furthermore, exposure of Ph+ ALL cells to EC141 resulted in activation of caspase-3, cleavage of poly (ADP-ribose) polymerase (PARP), and induction of apoptosis. In conclusion, our data suggest that EC141 is a potent Hsp90 inhibitor with activity against Ph+ ALL. Further studies to investigate the anticancer effect of EC141 either as a single agent, or in combination in Ph+ ALL and other hematological malignancies are warranted.
Tong
Wei-Gang
WG
Department of Leukemia, Unit 428, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA.
Estrov
Zeev
Z
Wang
Yongtao
Y
O'Brien
Susan
S
Faderl
Stefan
S
Harris
David M
DM
Van Pham
Quin
Q
Hazan-Halevy
Inbal
I
Liu
Zhiming
Z
Koch
Patricia
P
Kantarjian
Hagop
H
Keating
Michael J
MJ
Ferrajoli
Alessandra
A
D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3 / Q000187:drug effects / Q000378:metabolism; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects; D016044:Fusion Proteins, bcr-abl / Q000187:drug effects* / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000187:drug effects / Q000378:metabolism; D018841:HSP90 Heat-Shock Proteins / Q000037:antagonists & inhibitors*; D006801:Humans; D020128:Inhibitory Concentration 50; D011064:Poly Adenosine Diphosphate Ribose / Q000378:metabolism; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000188:drug therapy* / Q000473:pathology; D015854:Up-Regulation / Q000187:drug effects
D018840:HSP70 Heat-Shock Proteins; D018841:HSP90 Heat-Shock Proteins; D011064:Poly Adenosine Diphosphate Ribose; D016044:Fusion Proteins, bcr-abl; D053148:Caspase 3