WRN inhibition leads to its chromatin-associated degradation via the PIAS4-RNF4-p97/VCP axis

Area of Science:

• Oncology
• Molecular Biology
• Biochemistry

Background:

• Synthetic lethality is a promising cancer therapy strategy.
• Microsatellite instability-high (MSI-H) cancers rely on Werner (WRN) helicase for survival.
• Mechanisms regulating WRN spatiotemporal dynamics are not well understood.

Purpose of the Study:

• To investigate WRN dynamics in living cancer cells using single-molecule tracking (SMT).
• To identify regulatory pathways of WRN degradation.
• To explore therapeutic strategies targeting WRN in MSI-H cancers.

Main Methods:

• Single-molecule tracking (SMT) in living cancer cells.
• Utilized a WRN inhibitor and phenotypic screening.
• Investigated WRN degradation pathways, including p97/VCP and the PIAS4-RNF4 axis.
• Co-inhibition of WRN and SUMOylation.
• In vivo studies using an MSI-H mouse xenograft model.

Main Results:

• WRN inhibition traps WRN on chromatin, necessitating p97/VCP for extraction and proteasomal degradation in an MSI-H dependent manner.
• The PIAS4-RNF4 axis was identified as the pathway responsible for WRN degradation.
• Co-inhibition of WRN and SUMOylation demonstrated an additive toxic effect in MSI-H cells.
• Confirmed in vivo efficacy of WRN inhibition in an MSI-H mouse xenograft model.

Conclusions:

• Elucidated a regulatory mechanism for WRN spatiotemporal dynamics.
• Identified the PIAS4-RNF4 axis as crucial for WRN degradation.
• Demonstrated the therapeutic potential of combined WRN and SUMOylation inhibition in MSI-H cancers.
• Highlighted SMT as a valuable tool for drug discovery and mechanism-of-action studies.