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

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 PCA. detection in urine. Methods: The assay was based on interactions between unmodified gold nanopartides (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 (R-2 = 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.