Related Experiment Video
Updated: Jan 7, 2026

High-Throughput Cellular Profiling of Targeted Protein Degradation Compounds Using HiBiT CRISPR Cell Lines
Published on: November 9, 2020
Utilizing the HiBiT System to Identify CARM1 Degraders for Targeted Cancer Therapy
Megan Bacabac1, Mingshan Hu1, Fabao Liu1
1McArdle Laboratory for Cancer Research, University of Wisconsin-Madison, Madison, Wisconsin 53705, United States.
Abstract:
Preclinical studies validated coactivator-associated arginine methyltransferase 1 (CARM1) as a targetable therapeutic vulnerability, leading to the development of Proteolysis-Targeting Chimeras that specifically degrade CARM1. These compounds face significant translational challenges, including poor oral bioavailability and limited metabolic stability, which require extensive optimization. To identify more drug-like CARM1 degraders, we developed a high-throughput screening platform. We enabled antibody-free monitoring of CARM1 levels by fusing a HiBiT tag to CARM1 in MCF7 breast cancer cells. Complementation with LgBiT produces luciferase activity. Using this platform, we screened 1408 plant-derived natural product fractions to identify compounds that reduce CARM1 protein levels. This screen revealed two promising natural compounds, kusunokinin and exostemin, that specifically target CARM1 for degradation with selectivity over other protein arginine methyltransferases. Both compounds demonstrated functional anticancer activity, significantly inhibiting breast cancer cell colony formation and migration. Kusunokinin and exostemin represent lead compounds for developing next-generation CARM1-targeted therapeutics with enhanced translational potential.
Insights
Researchers identified natural compounds, kusunokinin and exostemin, that degrade coactivator-associated arginine methyltransferase 1 (CARM1). These compounds show promise for developing new cancer therapies with improved drug-like properties.
Area of Science:
- Biochemistry
- Molecular Biology
- Pharmacology
Background:
- Coactivator-associated arginine methyltransferase 1 (CARM1) is a validated therapeutic target.
- Existing CARM1 degraders face translational challenges like poor bioavailability.
Purpose of the Study:
- To discover novel, drug-like CARM1 degraders.
- To identify natural products with CARM1-degrading capabilities.
Main Methods:
- Developed a high-throughput screening platform using HiBiT-tagged CARM1 in MCF7 cells.
- Screened 1408 plant-derived natural product fractions.
- Assessed CARM1 degradation and selectivity via luciferase activity.
Main Results:
- Identified kusunokinin and exostemin as potent CARM1 degraders.
- These compounds showed selectivity for CARM1 over other methyltransferases.
- Demonstrated anticancer activity by inhibiting breast cancer cell colony formation and migration.
Conclusions:
- Kusunokinin and exostemin are promising lead compounds for next-generation CARM1-targeted cancer therapeutics.
- These natural compounds offer enhanced translational potential compared to existing degraders.

![Dynamic Imaging of Chimeric Antigen Receptor T Cells with [18F]Tetrafluoroborate Positron Emission Tomography/Computed Tomography](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F62334.jpg&w=3840&q=50)