Improved sensitivity and specificity for prostate cancer diagnosis based on the urine PCA3/PSA ratio acquired by sequence-specific RNA capture

摘要

Prostate cancer antigen 3 (PCA3) is a non-coding RNA fragment that is overexpressed in prostate cancer cells. However, the clinical applications of PCA3 are highly limited due to the instability of RNA and the lack of reliable and efficient RNA extraction and purification methods. Thus, in the present study, we compared three different methods of RNA extraction to further confirm the higher yield of commercial magnetic beads with poly-T functionalization and a capturer strand. The current protocols for RNA extraction of i) the phenol-chloroform method, ii) the affinity column method and iii) magnetic beads with poly-T functionalization and a capturer strand were applied separately for RNA extraction in urine samples. Reverse transcription-quantitative polymerase chain reaction was performed to evaluate the yield of the three methods of RNA extraction. Furthermore, 52 urine samples after prostate massage from patients suspected of a diagnosis of prostate cancer were collected. The Mag-Cap method and RT-PCR were applied to obtain the PCA3 score. The clinical value of the PCA3 score was investigated by comparison with the pathology of the prostate biopsy. The yield of the Mag-Cap method was higher than that of the phenol-chloroform method and commercial kits. Thirty-four patients were pathologically diagnosed with prostate cancer and 18 with benign prostatic hyperplasia (BPH). It was confirmed that the median PCA3 score was higher among the prostate cancer patients than those with benign disease (53.5 vs. 17, p=0.000). A sensitivity of 82.4% and a specificity of 77.8% were obtained when the cut-off value for the PCA3 score was 28.5. The Mag-Cap method was found to be more efficient for RNA extraction. The urinary PCA3 score is a promising method for prostate cancer screening, detection and diagnosis, and has the potential to reduce unnecessary prostate biopsies.