Related Experiment Video
Updated: Mar 29, 2026
High-Throughput Cellular Profiling of Targeted Protein Degradation Compounds Using HiBiT CRISPR Cell Lines
Published on: November 9, 2020
Systematic Optimization of Proteolysis-Targeting Chimeras for PIN1 Enables Selective Degradation and Antitumor
Yuying Ma1, Yang Teng1, Jinjin Liu1,2
1College of Pharmacy, Chongqing Medical University, Chongqing 400016, China.
Abstract:
Background: The peptidyl-prolyl cis-trans isomerase PIN1 regulates multiple oncogenic and tumor-suppressive pathways and is frequently overexpressed in human cancers. Although pharmacological inhibition of PIN1 has shown antitumor potential, existing PIN1-targeting degraders lack systematic structure-activity relationship (SAR) analyses and display inconsistent cellular efficacy, leaving the therapeutic relevance of PIN1 degradation unclear. Methods: Two series of PIN1-targeting PROTACs were designed using the covalent inhibitor sulfopin as the PIN1 binder and ligands for either cereblon (CRBN) or von Hippel-Lindau (VHL). Systematic SAR studies focused on linker structure and jointing atom composition. PIN1 degradation was assessed by Western blotting in multiple cancer cell lines, and further investigated through a series of computational and mechanistic experiments. Antitumor efficacy and safety were evaluated in an MCF-7 xenograft mouse model with preliminary pharmacokinetic analysis. Results: SAR analysis revealed that short, linear linkers and reduced hydrogen bond donor content markedly enhanced PIN1 degradation, whereas VHL-recruiting PROTACs showed inferior cellular activity. These studies identified PC2, a CRBN-recruiting PROTAC, as a lead compound. PC2 selectively induced ubiquitin-proteasome-dependent PIN1 degradation with minimal global proteomic or transcriptomic perturbation. Despite modest antiproliferative effects in vitro, PC2 significantly suppressed tumor growth in vivo without observable toxicity and achieved effective intratumoral PIN1 degradation. Conclusions: This study defines SAR-guided design principles for PIN1-targeting PROTACs and demonstrates that selective PIN1 degradation can produce robust antitumor activity in vivo. PC2 represents the first PIN1 degrader validated in animal models and supports targeted PIN1 degradation as a viable anticancer strategy.
Insights
Researchers developed novel PROTACs targeting PIN1 (peptidyl-prolyl cis-trans isomerase) for cancer therapy. The lead compound, PC2, effectively degraded PIN1 in vivo, showing significant tumor suppression with no observed toxicity, validating targeted PIN1 degradation as a cancer strategy.
Area of Science:
- Oncology
- Molecular Biology
- Drug Discovery
Background:
- Peptidyl-prolyl cis-trans isomerase PIN1 is crucial in cancer pathways and often overexpressed.
- Existing PIN1 inhibitors show promise, but PIN1 degraders lack detailed SAR and consistent efficacy.
- The therapeutic value of PIN1 degradation remains uncertain due to these limitations.
Purpose of the Study:
- To systematically analyze structure-activity relationships (SAR) of PIN1-targeting PROTACs.
- To identify potent and selective PIN1 degraders with enhanced cellular efficacy.
- To evaluate the in vivo antitumor activity and safety of lead PIN1 degraders.
Main Methods:
- Designed two series of PIN1-targeting PROTACs using sulfopin and CRBN/VHL ligands.
- Conducted systematic SAR studies focusing on linker characteristics.
- Assessed PIN1 degradation via Western blotting and mechanistic studies.
- Evaluated in vivo efficacy and safety in an MCF-7 xenograft mouse model.
Main Results:
- Short, linear linkers and reduced hydrogen bond donors improved PIN1 degradation.
- VHL-recruiting PROTACs exhibited lower cellular activity compared to CRBN-recruiting ones.
- PC2, a CRBN-recruiting PROTAC, selectively induced PIN1 degradation via the ubiquitin-proteasome system.
- PC2 demonstrated significant in vivo tumor suppression without toxicity and achieved intratumoral PIN1 degradation.
Conclusions:
- Established SAR-guided design principles for PIN1-targeting PROTACs.
- Demonstrated that selective PIN1 degradation can yield substantial in vivo antitumor effects.
- PC2 is the first PIN1 degrader validated in animal models, supporting PIN1 degradation as a viable anticancer strategy.
