G-Quadruplex Conformational Switching for miR-155-3p Detection Using a Ligand-Based Fluorescence Approach

Area of Science:

• Biochemistry
• Molecular Biology
• Analytical Chemistry

Background:

• MicroRNA-155-3p (miR-155-3p) is a significant biomarker in diseases like cancer.
• Sensitive and specific detection methods for miR-155-3p are essential for clinical applications.

Purpose of the Study:

• To develop a novel molecular beacon (MB-G4) for sensitive and specific detection of miR-155-3p.
• To characterize the conformational changes and optimize detection conditions for MB-G4.

Main Methods:

• Utilized a molecular beacon (MB-G4) that forms a G-quadruplex (G4) structure upon binding to miR-155-3p.
• Employed circular dichroism (CD) spectroscopy and native polyacrylamide gel electrophoresis (PAGE) for structural analysis.
• Optimized experimental conditions (KCl and NMM concentrations) and evaluated detection limit (LOD) and specificity.

Main Results:

• MB-G4 demonstrated a conformational switch from hairpin to G4 structure upon hybridization with miR-155-3p.
• The G4 structure was recognized by N-methyl mesoporphyrin IX (NMM), yielding a concentration-dependent fluorescence signal.
• Achieved a low detection limit (LOD) of 10.85 nM with high specificity against miR-155-5p.
• Successfully detected miR-155-3p in total RNA from A549 lung cancer cells.

Conclusions:

• MB-G4 provides a sensitive and specific platform for miR-155-3p detection.
• The G4 formation mechanism enables a reliable fluorescence-based assay.
• Validated potential for analyzing biological samples, including those from cancer cell lines.