Targeting a G-quadruplex from let-7e pre-miRNA with small molecules and nucleolin

Area of Science:

• Biochemistry
• Molecular Biology
• Oncology

Background:

• Let-7e precursor microRNA (pre-miRNA) is frequently dysregulated in cancers.
• Let-7e pre-miRNA can form a G-quadruplex (rG4) structure, a target of interest in oncology.
• Proteins like nucleolin and small molecules can influence rG4 structure stability and function.

Purpose of the Study:

• To characterize the rG4 structure formed by let-7e pre-miRNA.
• To assess the ability of small molecules to bind and stabilize this rG4 structure.
• To investigate the interaction between the rG4 structure, nucleolin, and small molecule ligands.

Main Methods:

• Circular dichroism (CD)
• Nuclear magnetic resonance (NMR)
• UV spectroscopy (TDS and IDS)
• Polyacrylamide gel electrophoresis (PAGE)
• Surface plasmon resonance (SPR)
• Confocal microscopy

Main Results:

• Demonstrated the formation of the rG4 structure in let-7e pre-miRNA sequence.
• Identified eight small molecules that bind to and stabilize the rG4 structure with high affinity (10⁻⁶ to 10⁻⁹ M dissociation constants).
• Showed that certain small molecules (360 A, PDS) can target the rG4, and TMPyP4 can block nucleolin binding.

Conclusions:

• The let-7e pre-miRNA rG4 structure can be formed and targeted by small molecules.
• Small molecules like 360 A and PDS show potential for controlling let-7e pre-miRNA biology.
• Targeting the let-7e pre-miRNA rG4 offers a novel approach for modulating microRNA biogenesis in cancer therapy.