Introduction

Novel strategies for candidate biomarker discovery in prostate cancer (PC) are needed to address the lack of specificity of prostate specific antigen (PSA) in PC screening and diagnosis. Urine is a very attractive biological fluid for prostate cancer biomarker discovery and measurement, since it is easy to obtain, non-invasive and may reflect biochemical processes within the prostate. Our aim is to search for proteins in the urine of patients with diagnosis of PC using isobaric labeling combined with high sensitive mass spectrometry-based proteomics.

Methods

In this study we performed isobaric labeling combined with high sensitive and accurate mass spectrometry-based proteomics to identify proteins that are differentially expressed in the urine of men with PC comparing with those with benign prostate hyperplasia (BPH).

Results

In total, 725 proteins were identified; amongst them 51 and 73 proteins were up and down regulated respectively in patients with PC. Two peptides from MMP-9 and Ly-6/neurotoxin-like were identified significantly up-regulated in PC and were further validated using a complementary targeted proteomic approach. Furthermore, we also quantified the expression of MMP9 in a set of 10 control and 17 prostate cancer urines, using ELISA, demonstrating that the expression of MMP9 is statistically higher in the urines from prostate cancer patients compared to controls (T-test, p<0.05). The activity of metalloproteinase was measured using zymography but no correlation between expression and activity in the urine samples from BPH and PC was observed.

Conclusions

Mass spectrometry based proteomics is a powerful method to discover and validate novel noninvasive candidate biomarkers in urine and our results open the potential of novel avenues for PC diagnosis.

Funding

CNPq