Aptamer-based approaches to detect nucleolin in prostate cancer

Area of Science:

• Biochemistry
• Molecular Biology
• Oncology

Background:

• Nucleolin (NCL) is implicated in various cellular processes, and its dysregulation is observed in cancers.
• Liquid biopsies offer a minimally invasive approach for cancer detection and monitoring.
• Assessing NCL expression in prostate cancer (PCa) could provide valuable diagnostic and prognostic information.

Purpose of the Study:

• To investigate the expression levels of nucleolin (NCL) in liquid biopsies of prostate cancer (PCa) patients.
• To evaluate the potential of NCL as a biomarker for PCa prognosis.
• To characterize a novel aptamer, AS1411-N5, for NCL detection.

Main Methods:

• Utilized a modified AS1411 aptamer (AS1411-N5) that exhibits increased fluorescence upon binding to NCL by forming a G-quadruplex (G4) structure.
• Performed biophysical studies to characterize the AS1411-N5 aptamer's G4 conformation and NCL binding affinity (K_D = 138.1 ± 5.5 nM).
• Employed an NCL-based ELISA assay to quantify NCL levels in peripheral blood mononuclear cells (PBMCs) from 158 individuals (PCa patients and healthy controls).

Main Results:

• AS1411-N5 demonstrated high affinity for NCL and formed a parallel G4 conformation in the presence of K+.
• Significantly higher NCL levels were observed in the PBMC lysate of PCa patients (mean 626.1 pg/mL) compared to healthy individuals (mean 198.5 pg/mL).
• NCL levels showed potential utility in identifying advanced stages of PCa and were detectable in spiked human plasma samples via a microfluidic assay.

Conclusions:

• Elevated NCL expression in PBMCs of PCa patients suggests its potential as a diagnostic biomarker.
• The AS1411-N5 aptamer is a promising tool for sensitive and specific NCL detection in liquid biopsies.
• NCL quantification in liquid biopsies could aid in prostate cancer diagnosis and prognosis assessment.