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- Steuber, T, et al.
(författare)
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Association of free-prostate specific antigen subfractions and human glandular kallikrein 2 with volume of benign and malignant prostatic tissue
- 2005
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Ingår i: The Prostate. - : Wiley. - 0270-4137 .- 1097-0045. ; 63:1, s. 13-18
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND. We investigated the association of different subfractions of prostate specific antigen (PSA) and human glandular kallikrein 2 (hK2), such as total PSA (tPSA), complexed PSA (cPSA), free PSA (fPSA), "single-chain Intact fPSA" (fPSA-I), "multi-chain nicked fPSA" (fPSA-N), and total hK2 with volumes of total prostate gland, transition zone (tz), and prostate cancer (PCa) tissue in patients with benign and malignant prostatic disease. METHODS. Serum samples were collected from men with negative biopsy (n = 164) and PCa (n = 252). Total and fPSA were measured using a commercially immunoassay. We measured hK2 and fPSA-I by previously reported in-house research assays specific for hK2 and single-chain, non-cleaved fPSA, respectively. Levels of fPSA-N (=fPSA-fPSA-I) and cPSA (=tPSA-fPSA) were calculated. Total prostate and tz volume were measured using transrectal ultrasound (TRUS); PCa volume was calculated using a computer assisted volumetric program. Association with tz and cancer volumes (CaVols) was performed by linear regression analysis. RESULTS. All PSA subfractions and hK2 were associated with tz volume in multivariable linear regression analysis. Only hK2, fPSA, and fPSA-N were significantly associated with CaVol in multivariable analysis, fPSA-I seemed to be cancer related. CONCLUSIONS. The multi-chain fPSA-N subfractions of fPSA may be a valuable predictor of both benign prostate hyperplasia (BPH) and CaVol that is likely to be more useful in predicting tz volumes than CaVols. fPSA-I may provide information on cancer without being influenced by the presence of BPH.
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| 2. |
- Niemela, P, et al.
(författare)
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Sensitive and specific enzymatic assay for the determination of precursor forms of prostate-specific antigen after an activation step
- 2002
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Ingår i: Clinical Chemistry. - 0009-9147. ; 48:8, s. 1257-1264
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Tidskriftsartikel (refereegranskat)abstract
- Background: The proteome of the serine protease prostate-specific antigen (PSA) and its enzymatic properties have been clarified only recently. We have developed a specific and sensitive method for the measurement of active PSA and used it to measure proPSA in blood. Methods: We used the synthetic peptide KGISSQY, which possesses a PSA-specific cleavage site, as substrate. To ascertain the specificity of the assay, we used an anti-PSA monoclonal antibody that captures known forms of PSA. An activation step enabled us to measure proPSA by converting it to mature, active PSA. Results: The detection limit of the optimized assay was 0.5 mug/L. In blood samples from patients, the activation step substantially increased the concentration of active PSA, thus showing the presence of proPSA in the samples. ProPSA was 0-79% (median, 45%) of the amount of free PSA in 15 samples with total PSA concentrations of 5.3-423 mug/L. In samples obtained from three benign prostatic hyperplasia (BPH) patients after transurethal resection of the prostate, no significant increase in activity was detected after the activation step, thus showing that proPSA was not a portion of free PSA in plasma of BPH patients. Conclusions: Proforms of PSA are a considerable fraction of free PSA in the blood of patients with increased total PSA. The approach described can be used to study the diagnostic value of proPSA and active PSA in patients with BPH and prostate cancer.
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