Colorimetric detection of PCA3 in urine for prostate cancer diagnosis using thiol-labeled PCR primer and unmodified gold nanoparticles

Abstract

Background: PCA3, a non-coding RNA, has been approved as a potential urinary biomarker for prostate cancer. However, PCA3 urine tests have some limitations. Therefore, we developed a colorimetric method for PCA3 detection in urine.

Methods: The assay was based on interactions between unmodified gold nanoparticles (AuNPs) and thiolated PCR products. Thiolated PCR products were amplified by RT-PCR using a thiol-labeled primer at the 5' end. Thiolated products of PCA3 bound to the surface of AuNPs and led to the prevention of salt-induced aggregation (red color). In the absence of the PCR products, AuNPs changed their color from red to blue due to the salt-induced aggregation. These changes were detected by the naked eye and spectrophotometer.

Results: Our assay was specific for PCA3 in prostate cancer cell lines with a visual detection limit of 31.25 ng/reaction. The absorption ratio 520/640 nm was linear against PCR product concentration (R² = 0.9798) in the reaction. This method is promising for discrimination of prostate cancer patients from both healthy controls and benign prostatic hyperplasia patients according to their urinary PCA3 expression levels.

Conclusions: This study established a simple, rapid, sensitive and specific assay for PCA3 detection which may be applicable for prostate cancer diagnosis.

Keywords: Colorimetric assay; Gold nanoparticle; PCA3; Prostate cancer; Urine.