Targeting Replication Fork Processing Synergizes with PARP Inhibition to Potentiate Lethality in Homologous Recombination Proficient Ovarian Cancers

Abstract Synthetic lethality in homologous recombination (HR)‐deficient cancers caused by Poly (ADP‐ribose) polymerase inhibitors (PARPi) has been classically attributed to its role in DNA repair. The mode of action of PARPi and resistance thereof are now believed to be predominantly replication ass...

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Main Authors: Ganesh Pai Bellare, Kshama Kundu, Papiya Dey, Krupa Thankam Philip, Nitish Chauhan, Muskan Sharma, Sankarsingh Kesharsingh Rajput, Birija Sankar Patro
Format: Article
Language:English
Published: Wiley 2025-05-01
Series:Advanced Science
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Online Access:https://doi.org/10.1002/advs.202410718
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author Ganesh Pai Bellare
Kshama Kundu
Papiya Dey
Krupa Thankam Philip
Nitish Chauhan
Muskan Sharma
Sankarsingh Kesharsingh Rajput
Birija Sankar Patro
author_facet Ganesh Pai Bellare
Kshama Kundu
Papiya Dey
Krupa Thankam Philip
Nitish Chauhan
Muskan Sharma
Sankarsingh Kesharsingh Rajput
Birija Sankar Patro
author_sort Ganesh Pai Bellare
collection DOAJ
description Abstract Synthetic lethality in homologous recombination (HR)‐deficient cancers caused by Poly (ADP‐ribose) polymerase inhibitors (PARPi) has been classically attributed to its role in DNA repair. The mode of action of PARPi and resistance thereof are now believed to be predominantly replication associated. Therefore, effective combinatorial approaches of targeting replication fork processing along with HR‐downregulation to target HR‐proficient and possibly PARPi‐resistant tumors are warranted. Stilbenes are a privileged class of molecules, which include resveratrol, pterostilbene, piceatannol, etc, that modulate both replication processes and RAD51‐expression. In this investigation, by screening a small library of stilbenes, including in‐house synthesized molecules, trans‐4,4′‐dihydroxystilbene (DHS) was discovered as a potent natural agent, which downregulates RAD51 expression and HR repair (GFP‐reporter assay). DHS induces extensive synergistic cell death in ovarian cancers when combined with talazoparib (PARPi). Mechanistically, DHS elicits replication‐stress through severely impeding replication fork progress, speed, and inducing fork‐asymmetry. This leads to robust induction of single stranded DNA (ssDNA) gaps and poly‐ADP‐ribosylation (PARylation) in S‐phase cells, signifying issues related to lagging (Okazaki) strand synthesis. PARPi, which abrogates PARylation, potentiates DHS induced ssDNA gaps, and their conversion into lethal double strand breaks through MRE11 action. Furthermore, the combination is highly effective in mitigating ovarian tumor xenograft growth in SCID mice and exhibited a good therapeutic‐index with no/minimal tissue‐toxicity.
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institution Kabale University
issn 2198-3844
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spelling doaj-art-0f21decab44b42e0af9fb355aa90ae292025-08-20T03:25:17ZengWileyAdvanced Science2198-38442025-05-011218n/an/a10.1002/advs.202410718Targeting Replication Fork Processing Synergizes with PARP Inhibition to Potentiate Lethality in Homologous Recombination Proficient Ovarian CancersGanesh Pai Bellare0Kshama Kundu1Papiya Dey2Krupa Thankam Philip3Nitish Chauhan4Muskan Sharma5Sankarsingh Kesharsingh Rajput6Birija Sankar Patro7Bio‐Organic Division Bhabha Atomic Research Centre Mumbai 400085 IndiaBio‐Organic Division Bhabha Atomic Research Centre Mumbai 400085 IndiaBio‐Organic Division Bhabha Atomic Research Centre Mumbai 400085 IndiaBio‐Organic Division Bhabha Atomic Research Centre Mumbai 400085 IndiaBio‐Organic Division Bhabha Atomic Research Centre Mumbai 400085 IndiaBio‐Organic Division Bhabha Atomic Research Centre Mumbai 400085 IndiaBio‐Organic Division Bhabha Atomic Research Centre Mumbai 400085 IndiaBio‐Organic Division Bhabha Atomic Research Centre Mumbai 400085 IndiaAbstract Synthetic lethality in homologous recombination (HR)‐deficient cancers caused by Poly (ADP‐ribose) polymerase inhibitors (PARPi) has been classically attributed to its role in DNA repair. The mode of action of PARPi and resistance thereof are now believed to be predominantly replication associated. Therefore, effective combinatorial approaches of targeting replication fork processing along with HR‐downregulation to target HR‐proficient and possibly PARPi‐resistant tumors are warranted. Stilbenes are a privileged class of molecules, which include resveratrol, pterostilbene, piceatannol, etc, that modulate both replication processes and RAD51‐expression. In this investigation, by screening a small library of stilbenes, including in‐house synthesized molecules, trans‐4,4′‐dihydroxystilbene (DHS) was discovered as a potent natural agent, which downregulates RAD51 expression and HR repair (GFP‐reporter assay). DHS induces extensive synergistic cell death in ovarian cancers when combined with talazoparib (PARPi). Mechanistically, DHS elicits replication‐stress through severely impeding replication fork progress, speed, and inducing fork‐asymmetry. This leads to robust induction of single stranded DNA (ssDNA) gaps and poly‐ADP‐ribosylation (PARylation) in S‐phase cells, signifying issues related to lagging (Okazaki) strand synthesis. PARPi, which abrogates PARylation, potentiates DHS induced ssDNA gaps, and their conversion into lethal double strand breaks through MRE11 action. Furthermore, the combination is highly effective in mitigating ovarian tumor xenograft growth in SCID mice and exhibited a good therapeutic‐index with no/minimal tissue‐toxicity.https://doi.org/10.1002/advs.202410718trans‐4,4′‐dihydroxystilbene (DHS)DNA replicationPARP inhibitorssDNA gapstalazoparib
spellingShingle Ganesh Pai Bellare
Kshama Kundu
Papiya Dey
Krupa Thankam Philip
Nitish Chauhan
Muskan Sharma
Sankarsingh Kesharsingh Rajput
Birija Sankar Patro
Targeting Replication Fork Processing Synergizes with PARP Inhibition to Potentiate Lethality in Homologous Recombination Proficient Ovarian Cancers
Advanced Science
trans‐4,4′‐dihydroxystilbene (DHS)
DNA replication
PARP inhibitor
ssDNA gaps
talazoparib
title Targeting Replication Fork Processing Synergizes with PARP Inhibition to Potentiate Lethality in Homologous Recombination Proficient Ovarian Cancers
title_full Targeting Replication Fork Processing Synergizes with PARP Inhibition to Potentiate Lethality in Homologous Recombination Proficient Ovarian Cancers
title_fullStr Targeting Replication Fork Processing Synergizes with PARP Inhibition to Potentiate Lethality in Homologous Recombination Proficient Ovarian Cancers
title_full_unstemmed Targeting Replication Fork Processing Synergizes with PARP Inhibition to Potentiate Lethality in Homologous Recombination Proficient Ovarian Cancers
title_short Targeting Replication Fork Processing Synergizes with PARP Inhibition to Potentiate Lethality in Homologous Recombination Proficient Ovarian Cancers
title_sort targeting replication fork processing synergizes with parp inhibition to potentiate lethality in homologous recombination proficient ovarian cancers
topic trans‐4,4′‐dihydroxystilbene (DHS)
DNA replication
PARP inhibitor
ssDNA gaps
talazoparib
url https://doi.org/10.1002/advs.202410718
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