Opportunity
The regulation of gene expression by RNA G-quadruplex (rG4) structures and their binding proteins (G4BPs) is a critical cellular process implicated in various diseases, including cancers and Alzheimer's disease (AD). Existing problems include the lack of specific therapeutic agents that can effectively target and disrupt the rG4-G4BP complexes, which are often overexpressed or dysregulated in pathological states. For instance, G4BPs like DHX36 and nucleolin are overexpressed in multiple cancers, promoting tumor progression, and rG4 motifs in transcripts such as amyloid precursor protein (APP) are involved in AD pathogenesis. Current approaches, such as small molecule inhibitors or siRNA, may lack specificity, efficiency, or rapid action, leading to off-target effects or delayed therapeutic outcomes. This creates a significant opportunity to develop novel agents that precisely degrade G4BPs to modulate rG4-mediated gene expression, offering a targeted strategy for treating these diseases.
Technology
This patent discloses novel conjugates, termed rG4-PROTACs (proteolytic targeting chimeras), designed to degrade G4BPs via the ubiquitin-proteasome system. The conjugate comprises a targeting moiety with a specific nucleic acid sequence (e.g., SEQ ID NO: 1, derived from human telomerase RNA component) that binds to G4BPs like DHX36, linked via click chemistry to a proteolytic moiety containing a ligand for E3 ubiquitin ligase (e.g., AHPC or pomalidomide). Upon cellular entry, the targeting moiety binds to the G4BP, while the proteolytic moiety recruits E3 ligase, inducing ubiquitination and degradation of the G4BP. This disrupts rG4-mediated gene regulation, such as reducing APP translation in AD or inhibiting oncogenic pathways in cancer. The innovation lies in using rG4 motifs as warheads for targeted protein degradation, offering high specificity and rapid action compared to traditional methods like siRNA.
Advantages
- High specificity: The rG4 motif selectively binds to G4BPs like DHX36, minimizing off-target effects.
- Efficient degradation: Conjugates like rG4_A achieve over 90% degradation of DHX36 at low nanomolar concentrations.
- Rapid action: Significant protein reduction occurs within hours, faster than siRNA-based approaches.
- Modular design: Click chemistry allows flexible linkage of targeting and proteolytic moieties for optimization.
- Broad applicability: Targets multiple G4BPs involved in various diseases, including cancers and AD.
- Proteasome-dependent mechanism: Degradation is blocked by proteasome inhibitors, ensuring controlled action.
Applications
- Treatment of Alzheimer's disease by degrading G4BPs to reduce APP protein expression.
- Therapy for cancers (e.g., lung, cervical, colon cancer) by targeting overexpressed G4BPs like DHX36.
- Regulation of gene expression in conditions involving rG4-mediated translation, such as muscle regeneration via Gnai2 modulation.
- Development of lipid nanoparticle (LNP) formulations for enhanced cellular delivery of conjugates.
- Use in research tools to study rG4-G4BP interactions and their roles in cellular processes.
