MDM2 Antagonist Idasanutlin Reduces HDAC1/2 Abundance and Corepressor Partners but Not HDAC3

Area of Science:

• Biochemistry
• Molecular Biology
• Drug Discovery

Background:

• Histone deacetylases 1-3 (HDAC1-3) regulate chromatin structure and gene transcription.
• HDACs are drug targets for oncology, neurodegenerative, and cardiovascular diseases.
• Proteolysis targeting chimeras (PROTACs) are emerging therapeutics.

Purpose of the Study:

• To synthesize novel heterobifunctional molecules (PROTACs) to degrade HDAC1-3.
• To investigate the potential of recruiting the MDM2 E3 ligase for HDAC degradation.
• To explore dual-targeting therapeutic strategies.

Main Methods:

• Synthesis of four novel heterobifunctional molecules (PROTACs).
• Utilizing idasanutlin, an MDM2 inhibitor, to recruit the MDM2 E3 ligase.
• Assessing the degradation of HDAC1-3 and corepressor components (LSD1, SIN3A).

Main Results:

• Two PROTACs reduced HDAC1 and HDAC2 abundance selectively over HDAC3.
• These PROTACs also reduced HDAC1/2 corepressor components LSD1 and SIN3A.
• Idasanutlin alone, without the PROTAC linker, reduced HDAC1 and HDAC2 levels.

Conclusions:

• A potential association exists between the MDM2 E3 ligase and HDAC1/2 corepressor complexes.
• Idasanutlin's ability to affect HDAC1/2 suggests a novel mechanism.
• This finding could inform the design of future dual-targeting therapeutics, including PROTACs.