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Prostate cancer is the leading type of cancer diagnosed in men. Serum prostate-specific antigen levels and digital rectal exam are far from perfect when it comes to differentiation of patients with prostate cancer and benign prostatic hyperplasia. In this study, we attempt to determine whether amino acids can be used as prostate cancer biomarkers. Concentrations of derivatized amino acids and amines were quantified by liquid chromatography tandem mass spectrometry. A total of 100 urine samples from the two groups including samples provided before and after prostate massage were examined quantitatively for amino acid and amine concentrations with 50 urine samples collected from cancer patients and 50 samples from patients diagnosed with benign prostatic hyperplasia. Arginine, homoserine, and proline were more abundant in urine samples of cancer patients compared with arginine, homoserine, and proline levels determined in urine collected from patients with benign growth. We also show that sarcosine is not a definitive indicator of prostate cancer when analyzed in urine samples collected either before or after prostate massage.

dom urine samples (without prostate massage) were collected from 163 men who were stratified into 4 groups: TRUS prostate biopsy negative (Bx Neg, n 39), TRUS biopsy positive (Bx Pos, n 47), post-radical prostatectomy (RP, n 37) and controls (males 35 yrs, n 40). Additionally, whole-mount paraffin embedded prostate sections were obtained from 11 patients who underwent RP and had pre-RP urine specimens available (7 T:E positive, 4 T:E negative in pre-RP urine). Urine samples were stored at 4°C and 0.8 m filtration was used to remove whole cells and debris. Urinary exosomal RNA and tissue RNA were isolated using an in-house technique (Exosome Diagnostics, NY) and analyzed using RP-qPCR. RESULTS: Mean serum PSA levels were similar in the Bx Neg and Bx Pos groups. All groups except the control (males 35 yrs) were age matched. T:E fusion events were found to occur in 68% of Bx Pos and 44% of Bx Neg patients. Only 5% of controls expressed T:E and no patient in the post RP group had positive T:E detection. Furthermore, T:E expression was lost in the 4 Bx Pos patients that underwent prostatectomy and were retested following surgery. Tissue analysis revealed positive T:E in 8 of 11 prostates. T:E expression concordance between urine and tissue occurred in 10 of 11 (91%) patients with a sensitivity and specificity of 89% and 100%, respectively. CONCLUSIONS: The detection rate of the T:E fusion in the Bx Pos group using urinary exosomal RNA was consistent with previous reports using tissue analyses. Our study exhibited near perfect concordance between urinary exosomal mRNA with matched prostate tissue analysis. The detection of T:E expression in the urine of patients with a negative TRUS biopsy may be due to false negative biopsy results or assay detection of T:E expression in premalignant lesions. The unique stability and yield of urinary exosomal RNA will broaden the role of exosomes in future diagnostic testing and simplify sample handing without the variability and patient discomfort inherent to prostate massage.

Measurement of serum prostate specific antigen (PSA) is commonly used to evaluate the prostate gland in a variety of clinical settings. We examined the effects of prostatic manipulations, including digital rectal examination, prostate massage, transrectal ultrasonography and transrectal needle biopsy, on serum PSA levels in 199 men. We detected no clinically significant difference between serum PSA levels obtained immediately before and at 5 or 90 minutes after rectal examination in 43 men. We observed falsely increased PSA levels (to greater than 4 ng./ml., Tandem-R) in 1 of 17 men (6%) following prostatic massage and in 3 of 27 men (11%) following ultrasonography. Transrectal needle biopsy caused an immediate increase in serum PSA in 92 of 100 men. In 29 of these 92 men (32%) when followed weekly serum PSA levels did not return to baseline as expected according to the published serum PSA half-life of 2 to 3 days. Biopsies taking 3 or fewer cores (7 patients) resulted in a smaller increase in serum PSA (mean 1.63 +/- 1.12 times the baseline level versus 6.24 +/- 1.10 times baseline, p less than 0.03) and a proportionally shorter duration of PSA elevation (mean 1.43 +/- 0.48 weeks versus 2.13 +/- 0.14 weeks, p = 0.20) than those taking 4 or more cores (93 patients). Prostate size and the presence of cancer had no influence on the duration of PSA elevation following biopsy. We conclude that digital rectal examination, prostatic massage and ultrasonography have minimal effects on serum PSA levels in most patients. However, prostatic needle biopsy usually causes marked elevations of serum PSA levels with a persistent PSA leak into the blood stream lasting longer than expected from the serum half-life of PSA in approximately 25% of the patients.