The ubiquitin-activating enzyme E1 as a therapeutic target for the treatment of leukemia and multiple myeloma.
The proteasomal pathway of protein degradation involves 2 discrete steps: ubiquitination and degradation. Here, we evaluated the effects of inhibiting the ubiquitination pathway at the level of the ubiquitin-activating enzyme UBA1 (E1). By immunoblotting, leukemia cell lines and primary patient samples had increased protein ubiquitination. Therefore, we examined the effects of genetic and chemical inhibition of the E1 enzyme. Knockdown of E1 decreased the abundance of ubiquitinated proteins in leukemia and myeloma cells and induced cell death. To further investigate effects of E1 inhibition in malignancy, we discovered a novel small molecule inhibitor, 3,5-dioxopyrazolidine compound, 1-(3-chloro-4-fluorophenyl)-4-[(5-nitro-2-furyl)methylene]-3,5-pyrazolidinedione (PYZD-4409). PYZD-4409 induced cell death in malignant cells and preferentially inhibited the clonogenic growth of primary acute myeloid leukemia cells compared with normal hematopoietic cells. Mechanistically, genetic or chemical inhibition of E1 increased expression of E1 stress markers. Moreover, BI-1 overexpression blocked cell death after E1 inhibition, suggesting ER stress is functionally important for cell death after E1 inhibition. Finally, in a mouse model of leukemia, intraperitoneal administration of PYZD-4409 decreased tumor weight and volume compared with control without untoward toxicity. Thus, our work highlights the E1 enzyme as a novel target for the treatment of hematologic malignancies.
Xu
G Wei
GW
The Princess Margaret Hospital, The Ontario Cancer Institute, Toronto, ON, Canada.
Ali
Mohsin
M
Wood
Tabitha E
TE
Wong
Derek
D
Maclean
Neil
N
Wang
Xiaoming
X
Gronda
Marcela
M
Skrtic
Marko
M
Li
Xiaoming
X
Hurren
Rose
R
Mao
Xinliang
X
Venkatesan
Meenakshi
M
Beheshti Zavareh
Reza
R
Ketela
Troy
T
Reed
John C
JC
Rose
David
D
Moffat
Jason
J
Batey
Robert A
RA
Dhe-Paganon
Sirano
S
Schimmer
Aaron D
AD
D000818:Animals; D016923:Cell Death / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D056743:Cyclin D3 / Q000378:metabolism; D004195:Disease Models, Animal; D004354:Drug Screening Assays, Antitumor; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000473:pathology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D055785:Gene Knockdown Techniques; D006413:Hematopoietic System / Q000166:cytology / Q000187:drug effects; D006801:Humans; D007938:Leukemia / Q000201:enzymology* / Q000628:therapy*; D051379:Mice; D009101:Multiple Myeloma / Q000201:enzymology* / Q000628:therapy*; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D054852:Small Molecule Libraries / Q000494:pharmacology; D013312:Stress, Physiological / Q000187:drug effects; D013997:Time Factors; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D044764:Ubiquitin-Activating Enzymes / Q000037:antagonists & inhibitors / Q000378:metabolism*; D054875:Ubiquitination / Q000187:drug effects
D056743:Cyclin D3; D004791:Enzyme Inhibitors; D054852:Small Molecule Libraries; D016159:Tumor Suppressor Protein p53; D044764:Ubiquitin-Activating Enzymes