Related Experiment Video

Updated: May 22, 2025

Visualizing DNA Damage Repair Proteins in Patient-Derived Ovarian Cancer Organoids via Immunofluorescence Assays
04:07

Visualizing DNA Damage Repair Proteins in Patient-Derived Ovarian Cancer Organoids via Immunofluorescence Assays

Published on: February 24, 2023

1.6K

Targeting Replication Fork Processing Synergizes with PARP Inhibition to Potentiate Lethality in Homologous

Ganesh Pai Bellare1,2, Kshama Kundu1, Papiya Dey1

  • 1Bio-Organic Division, Bhabha Atomic Research Centre, Mumbai, 400085, India.

Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
|March 16, 2025
PubMed

Insights

Trans-4,4'-dihydroxystilbene (DHS) combined with Poly (ADP-ribose) polymerase inhibitors (PARPi) shows promise for treating ovarian cancers by targeting replication stress and homologous recombination repair. This combination effectively reduces tumor growth with minimal toxicity.

Area of Science:

  • Oncology
  • Molecular Biology
  • Genetics

Background:

  • Synthetic lethality in homologous recombination (HR)-deficient cancers treated with Poly (ADP-ribose) polymerase inhibitors (PARPi) is increasingly linked to replication processes rather than solely DNA repair.
  • Targeting replication fork processing alongside HR-downregulation offers a strategy for HR-proficient and PARPi-resistant tumors.
  • Stilbenes, like resveratrol, are known to modulate replication and RAD51 expression.

Purpose of the Study:

  • To identify novel agents that downregulate RAD51 expression and homologous recombination (HR) repair.
  • To evaluate the efficacy of combining a novel stilbene, trans-4,4 -dihydroxystilbene (DHS), with a PARPi in ovarian cancer models.
  • To elucidate the underlying mechanisms of action for the combination therapy.

Main Methods:

  • Screening of a stilbene library to identify compounds affecting RAD51 expression and HR repair using a GFP-reporter assay.
  • Combination treatment of ovarian cancer cells with DHS and talazoparib (PARPi).
  • Assessment of replication stress, single-stranded DNA (ssDNA) gaps, poly-ADP-ribosylation (PARylation), and DNA double-strand breaks.
  • In vivo studies using ovarian tumor xenografts in SCID mice to evaluate therapeutic efficacy and toxicity.

Main Results:

  • Trans-4,4 -dihydroxystilbene (DHS) was identified as a potent natural agent that downregulates RAD51 expression and HR repair.
  • DHS synergistically enhanced cell death in ovarian cancers when combined with talazoparib (PARPi).
  • Mechanistically, DHS induced replication stress by impeding replication fork progression and speed, leading to ssDNA gaps and PARylation, which were potentiated by PARPi to cause lethal double-strand breaks.
  • The combination therapy significantly inhibited ovarian tumor xenograft growth with minimal observed tissue toxicity.

Conclusions:

  • Trans-4,4 -dihydroxystilbene (DHS) is a potent natural agent that induces replication stress and downregulates HR repair.
  • The combination of DHS and talazoparib (PARPi) demonstrates significant synergistic efficacy in ovarian cancer treatment, targeting both HR-proficient and potentially PARPi-resistant tumors.
  • This combination therapy warrants further investigation as a novel therapeutic strategy for ovarian cancer, showing promising efficacy and a favorable toxicity profile.
Keywords:
DNA replicationPARP inhibitorssDNA gapstalazoparibtrans‐4,4′‐dihydroxystilbene (DHS)

More Related Videos

Quantifying Replication Stress in Ovarian Cancer Cells Using Single-Stranded DNA Immunofluorescence06:25

Quantifying Replication Stress in Ovarian Cancer Cells Using Single-Stranded DNA Immunofluorescence

Published on: February 10, 2023

2.0K
Assessment of Global DNA Double-Strand End Resection using BrdU-DNA Labeling coupled with Cell Cycle Discrimination Imaging06:44

Assessment of Global DNA Double-Strand End Resection using BrdU-DNA Labeling coupled with Cell Cycle Discrimination Imaging

Published on: April 28, 2021

3.9K

Related Concept Videos

Restarting Stalled Replication Forks02:37

Restarting Stalled Replication Forks

DNA replication is initiated at sites containing predefined DNA sequences known as origins of replication. DNA is unwound at these sites by the minichromosome maintenance (MCM) helicase and other factors such as Cdc45 and the associated GINS complex.The unwound single strands are protected by replication protein A (RPA) until DNA polymerase starts synthesizing DNA at the 5’ end of the strand in the same direction as the replication fork. To prevent the replication fork from falling apart,...
5.7K
The DNA Replication Fork01:02

The DNA Replication Fork

An organism’s genome needs to be duplicated in an efficient and error-free manner for its growth and survival. The replication fork is a Y-shaped active region where two strands of DNA are separated and replicated continuously. The coupling of DNA unzipping and complementary strand synthesis is a characteristic feature of a replication fork.   Organisms with small circular DNA, such as E. coli, often have a single origin of replication; therefore, they have only two replication...
35.3K
Homologous Recombination02:31

Homologous Recombination

The basic reaction of homologous recombination (HR) involves two chromatids that contain DNA sequences sharing a significant stretch of identity. One of these sequences uses a strand from another as a template to synthesize DNA in an enzyme-catalyzed reaction. The final product is a novel amalgamation of the two substrates. To ensure an accurate recombination of sequences, HR is restricted to the S and G2 phases of the cell cycle. At these stages, the DNA has been replicated already and the...
50.0K
Translesion DNA Polymerases02:10

Translesion DNA Polymerases

Translesion (TLS) polymerases rescue stalled DNA polymerases at sites of damaged bases by replacing the replicative polymerase and installing a nucleotide across the damaged site. Doing so, TLS allows additional time for the cell to repair the damage before resuming regular DNA replication.
TLS polymerases are found in all three domains of life - archaea, bacteria, and eukaryotes. Of the different classes of TLS polymerases, members of the Y family are fitted with specialized structures that...
9.7K
Conservative Site-specific Recombination and Phase Variation02:53

Conservative Site-specific Recombination and Phase Variation

Because the DNA segments are cut and reorganized in a direction-specific manner, site-specific recombination has emerged as an efficient genetic engineering technique. Flippase and Cyclization recombinases or Flp and Cre, respectively, are two members of the tyrosine recombinase family derived from bacteriophages, that are used to mediate site-specific DNA insertions, deletions, and targeted expression of proteins in mammalian cell lines.
The recognition sites for Cre recombinase called LoxP...
5.9K
DNA Damage can Stall the Cell Cycle02:37

DNA Damage can Stall the Cell Cycle

In response to DNA damage, cells can pause the cell cycle to assess and repair the breaks. However, the cell must check the DNA at certain critical stages during the cell cycle. If the cell cycle pauses before DNA replication, the cells will contain twice the amount of DNA. On the other hand, if cells arrest after DNA replication but before mitosis, they will contain four times the normal amount of DNA. With a host of specialized proteins at their disposal,cells must use the right protein at...
9.0K