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.jpg): Failed to open stream: No such file or directory in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 117 Cancer+Res
2015 ; 75
(18
): 3865-3878
Nephropedia Template TP
gab.com Text
Twit Text FOAVip
Twit Text #
English Wikipedia
The SMARCA2/4 ATPase Domain Surpasses the Bromodomain as a Drug Target in
SWI/SNF-Mutant Cancers: Insights from cDNA Rescue and PFI-3 Inhibitor Studies
#MMPMID26139243
Vangamudi B
; Paul TA
; Shah PK
; Kost-Alimova M
; Nottebaum L
; Shi X
; Zhan Y
; Leo E
; Mahadeshwar HS
; Protopopov A
; Futreal A
; Tieu TN
; Peoples M
; Heffernan TP
; Marszalek JR
; Toniatti C
; Petrocchi A
; Verhelle D
; Owen DR
; Draetta G
; Jones P
; Palmer WS
; Sharma S
; Andersen JN
Cancer Res
2015[Sep]; 75
(18
): 3865-3878
PMID26139243
show ga
The SWI/SNF multisubunit complex modulates chromatin structure through the
activity of two mutually exclusive catalytic subunits, SMARCA2 and SMARCA4, which
both contain a bromodomain and an ATPase domain. Using RNAi, cancer-specific
vulnerabilities have been identified in SWI/SNF-mutant tumors, including
SMARCA4-deficient lung cancer; however, the contribution of conserved, druggable
protein domains to this anticancer phenotype is unknown. Here, we functionally
deconstruct the SMARCA2/4 paralog dependence of cancer cells using
bioinformatics, genetic, and pharmacologic tools. We evaluate a selective
SMARCA2/4 bromodomain inhibitor (PFI-3) and characterize its activity in
chromatin-binding and cell-functional assays focusing on cells with altered
SWI/SNF complex (e.g., lung, synovial sarcoma, leukemia, and rhabdoid tumors). We
demonstrate that PFI-3 is a potent, cell-permeable probe capable of displacing
ectopically expressed, GFP-tagged SMARCA2-bromodomain from chromatin, yet
contrary to target knockdown, the inhibitor fails to display an antiproliferative
phenotype. Mechanistically, the lack of pharmacologic efficacy is reconciled by
the failure of bromodomain inhibition to displace endogenous, full-length SMARCA2
from chromatin as determined by in situ cell extraction, chromatin
immunoprecipitation, and target gene expression studies. Furthermore, using
inducible RNAi and cDNA complementation (bromodomain- and ATPase-dead
constructs), we unequivocally identify the ATPase domain, and not the bromodomain
of SMARCA2, as the relevant therapeutic target with the catalytic activity
suppressing defined transcriptional programs. Taken together, our complementary
genetic and pharmacologic studies exemplify a general strategy for multidomain
protein drug-target validation and in case of SMARCA2/4 highlight the potential
for drugging the more challenging helicase/ATPase domain to deliver on the
promise of synthetic-lethality therapy.
|*Molecular Targeted Therapy
[MESH]
|Azabicyclo Compounds/*pharmacology
[MESH]
|Binding, Competitive
[MESH]
|Catalysis
[MESH]
|Cell Line, Tumor
[MESH]
|Chromatin Assembly and Disassembly/*drug effects
[MESH]