Development of Parallel Reaction Monitoring Assays for the Detection of Aggressive Prostate Cancer Using Urinary Glycoproteins

Recently,
we have found that two urinary glycoproteins, prostatic
acid phosphatase (ACPP) and clusterin (CLU), combined with serum prostate-specific
antigen (PSA) can serve as a three-signature panel for detecting aggressive
prostate cancer (PCa) based on a quantitative glycoproteomic study.
To facilitate the translation of candidates into clinically applicable
tests, robust and accurate targeted parallel reaction monitoring (PRM)
assays that can be widely adopted in multiple labs were developed
in this study. The developed PRM assays for the urinary glycopeptides,
FLN*ESYK from ACPP and EDALN*ETR from CLU, demonstrated good repeatability
and a sufficient working range covering three to four orders of magnitude,
and their performance in differentiating aggressive PCa was assessed
by the quantitative analysis of urine specimens collected from 69
nonaggressive (Gleason score = 6) and 73 aggressive (Gleason ≥
8) PCa patients. When ACPP combined with CLU, the discrimination power
was improved from an area under a curve (AUC) of 0.66 to 0.78. By
combining ACPP, CLU, and serum PSA to form a three-signature panel,
the AUC was further improved to 0.83 (sensitivity: 84.9%, specificity:
66.7%). Since the serum PSA test alone had an AUC of 0.68, our results
demonstrated that the new urinary glycopeptide PRM assays can serve
as an adjunct to the serum PSA test to achieve better predictive power
toward aggressive PCa. In summary, our developed PRM assays for urinary
glycopeptides were successfully applied to clinical PCa urine samples
with a promising performance in aggressive PCa detection.