Related Experiment Video
Updated: May 22, 2025
High-Throughput Cellular Profiling of Targeted Protein Degradation Compounds Using HiBiT CRISPR Cell Lines
Published on: November 9, 2020
Development of p300-targeting degraders with enhanced selectivity and onset of degradation
Graham P Marsh1, Mark S Cooper1, Sean Goggins1
1Bio-Techne (Tocris) The Watkins Building, Atlantic Road, Avonmouth Bristol BS11 9QD UK hannah.maple@bio-techne.com.
Abstract:
p300 and CBP are paralogous epigenetic regulators that are considered promising therapeutic targets for cancer treatment. Small molecule p300/CBP inhibitors have so far been unable to differentiate between these closely related proteins, yet selectivity is desirable in order to probe their distinct cellular functions. Additionally, in multiple cancers, loss-of-function CREBBP mutations set up a paralog dependent synthetic lethality with p300, that could be exploited with a selective therapeutic agent. To address this, we developed p300-targeting heterobifunctional degraders that recruit p300 through its HAT domain using the potent spiro-hydantoin-based inhibitor, iP300w. Lead degrader, BT-O2C, demonstrates improved selectivity and a faster onset of action compared to a recently disclosed A 485-based degrader in HAP1 cells and is cytotoxic in CIC::DUX4 sarcoma (CDS) cell lines (IC50 = 152-221 nM), significantly reducing expression of CDS target genes (ETV1, ETV4, ETV5). Taken together, our results demonstrate that BT-O2C represents a useful tool degrader for further exploration of p300 degradation as a therapeutic strategy.
Insights
Researchers developed a novel p300-targeting degrader, BT-O2C, to selectively inhibit p300 epigenetic regulation in cancer. This new tool shows promise for cancer therapy by effectively reducing cancer gene expression and demonstrating cytotoxicity.
Area of Science:
- Epigenetics and Molecular Biology
- Cancer Therapeutics
- Drug Discovery
Background:
- p300 and CBP are closely related epigenetic regulators and potential cancer drug targets.
- Current inhibitors lack selectivity between p300 and CBP, hindering exploration of their distinct functions.
- Loss-of-function mutations in CREBBP create synthetic lethality exploitable by selective p300 agents.
Purpose of the Study:
- To develop selective p300-targeting heterobifunctional degraders.
- To assess the efficacy and selectivity of the lead degrader, BT-O2C.
- To evaluate BT-O2C as a tool for studying p300 degradation in cancer therapy.
Main Methods:
- Design and synthesis of p300-targeting heterobifunctional degraders using a spiro-hydantoin-based inhibitor (iP300w).
- Evaluation of degrader selectivity and onset of action in HAP1 cells.
- Assessment of cytotoxicity and target gene expression reduction in CIC::DUX4 sarcoma (CDS) cell lines.
Main Results:
- The lead degrader, BT-O2C, exhibited improved selectivity and faster action than a comparator.
- BT-O2C demonstrated significant cytotoxicity in CDS cell lines (IC50 = 152-221 nM).
- BT-O2C effectively reduced the expression of key CDS target genes (ETV1, ETV4, ETV5).
Conclusions:
- BT-O2C is a selective p300 degrader with potential therapeutic applications.
- This degrader serves as a valuable tool for investigating p300 degradation as a cancer treatment strategy.
- The findings support further development of p300-targeted therapies for cancers with CREBBP mutations.
