TY - JOUR
T1 - Discovery of a small-molecule inhibitor that traps Polθ on DNA and synergizes with PARP inhibitors
AU - Fried, William
AU - Tyagi, Mrityunjay
AU - Minakhin, Leonid
AU - Chandramouly, Gurushankar
AU - Tredinnick, Taylor
AU - Ramanjulu, Mercy
AU - Auerbacher, William
AU - Calbert, Marissa
AU - Rusanov, Timur
AU - Hoang, Trung
AU - Borisonnik, Nikita
AU - Betsch, Robert
AU - Krais, John J.
AU - Wang, Yifan
AU - Vekariya, Umeshkumar M.
AU - Gordon, John
AU - Morton, George
AU - Kent, Tatiana
AU - Skorski, Tomasz
AU - Johnson, Neil
AU - Childers, Wayne
AU - Chen, Xiaojiang S.
AU - Pomerantz, Richard T.
N1 - Publisher Copyright:
© The Author(s) 2024.
PY - 2024/3/5
Y1 - 2024/3/5
N2 - The DNA damage response (DDR) protein DNA Polymerase θ (Polθ) is synthetic lethal with homologous recombination (HR) factors and is therefore a promising drug target in BRCA1/2 mutant cancers. We discover an allosteric Polθ inhibitor (Polθi) class with 4–6 nM IC50 that selectively kills HR-deficient cells and acts synergistically with PARP inhibitors (PARPi) in multiple genetic backgrounds. X-ray crystallography and biochemistry reveal that Polθi selectively inhibits Polθ polymerase (Polθ-pol) in the closed conformation on B-form DNA/DNA via an induced fit mechanism. In contrast, Polθi fails to inhibit Polθ-pol catalytic activity on A-form DNA/RNA in which the enzyme binds in the open configuration. Remarkably, Polθi binding to the Polθ-pol:DNA/DNA closed complex traps the polymerase on DNA for more than forty minutes which elucidates the inhibitory mechanism of action. These data reveal a unique small-molecule DNA polymerase:DNA trapping mechanism that induces synthetic lethality in HR-deficient cells and potentiates the activity of PARPi.
AB - The DNA damage response (DDR) protein DNA Polymerase θ (Polθ) is synthetic lethal with homologous recombination (HR) factors and is therefore a promising drug target in BRCA1/2 mutant cancers. We discover an allosteric Polθ inhibitor (Polθi) class with 4–6 nM IC50 that selectively kills HR-deficient cells and acts synergistically with PARP inhibitors (PARPi) in multiple genetic backgrounds. X-ray crystallography and biochemistry reveal that Polθi selectively inhibits Polθ polymerase (Polθ-pol) in the closed conformation on B-form DNA/DNA via an induced fit mechanism. In contrast, Polθi fails to inhibit Polθ-pol catalytic activity on A-form DNA/RNA in which the enzyme binds in the open configuration. Remarkably, Polθi binding to the Polθ-pol:DNA/DNA closed complex traps the polymerase on DNA for more than forty minutes which elucidates the inhibitory mechanism of action. These data reveal a unique small-molecule DNA polymerase:DNA trapping mechanism that induces synthetic lethality in HR-deficient cells and potentiates the activity of PARPi.
KW - DNA/metabolism
KW - BRCA2 Protein/genetics
KW - DNA-Directed DNA Polymerase/metabolism
KW - Poly(ADP-ribose) Polymerase Inhibitors/pharmacology
KW - DNA Repair
KW - Humans
KW - Homologous Recombination
KW - BRCA1 Protein/genetics
UR - http://www.scopus.com/inward/record.url?scp=85189610702&partnerID=8YFLogxK
U2 - 10.1038/s41467-024-46593-1
DO - 10.1038/s41467-024-46593-1
M3 - Article
C2 - 38580648
AN - SCOPUS:85189610702
SN - 2041-1723
VL - 15
SP - 2862
JO - Nature Communications
JF - Nature Communications
IS - 1
M1 - 2862
ER -
