Development of decoy oligonucleotide-warheaded chimeric molecules targeting STAT3.

Area of Science:

• Biochemistry
• Molecular Biology
• Drug Discovery

Background:

• Proteolysis-targeting chimera (PROTAC) technology is revolutionizing drug development, with over 20 PROTACs in clinical trials.
• Oligonucleotide-warheaded PROTACs offer a novel approach for degrading DNA-binding proteins like transcription factors.
• Signal transducer and activator of transcription 3 (STAT3) is a challenging target protein implicated in various cancers.

Purpose of the Study:

• To develop and evaluate an oligonucleotide-warheaded PROTAC for targeted degradation of STAT3.
• To investigate the mechanism of STAT3 degradation mediated by the novel PROTAC.
• To assess the therapeutic potential of STAT3 degradation in cancer cells.

Main Methods:

• Conjugation of a double-stranded decoy oligonucleotide specific to STAT3 with E3 binders (pomalidomide, VH032, LCL161) to create PROTACs.
• Treatment of NCI-H2087 cells with the PROTAC POM-STAT3 (recruiting CRBN) and assessment of STAT3 degradation.
• Validation of STAT3 degradation mechanism using scrambled oligonucleotides, competitive binding assays, and inhibitors of the ubiquitin-proteasome system.

Main Results:

• The PROTAC POM-STAT3 potently induced STAT3 degradation by recruiting the E3 ligase CRBN.
• STAT3 degradation was sequence-dependent and mediated by the ubiquitin-proteasome system.
• POM-STAT3 treatment significantly reduced NCI-H2087 cell viability, indicating cytocidal activity.

Conclusions:

• Decoy oligonucleotide-warheaded PROTACs are effective tools for degrading challenging protein targets like STAT3.
• POM-STAT3 demonstrates potent STAT3 degradation and significant anticancer activity, highlighting its therapeutic potential.
• This approach offers a promising strategy for targeting oncogenic transcription factors in cancer therapy.