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- Nurmikko, P., et al.
(författare)
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Production and characterization of novel anti-prostate-specific antigen (PSA) monoclonal antibodies that do not detect internally cleaved Lys145-Lys146 inactive PSA
- 2000
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Ingår i: Clinical Chemistry. - : Oxford University Press (OUP). - 0009-9147 .- 1530-8561. ; 46:10, s. 1610-1618
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Tidskriftsartikel (refereegranskat)abstract
- Background: The nature of free, uncomplexed prostate-specific antigen (s) in the circulation is still unknown. In this study, we developed novel anti-PSA antibodies using PSA produced by a metastasized cancer cell line, LNCaP, as an immunogen. Methods: Hybridoma cell lines were screened with different methods that aimed at finding antibodies specific for the forms of free PSA produced by LNCaP cell line. Obtained antibodies were further studied for their characteristics related to previously characterized monoclonal antibodies. Results: Numerous anti-PSA antibodies were obtained, of which four represented unique epitopes previously unrecognized by us. One free-PSA-specific antibody was bound to PSA on two distinct epitopes, and one antibody was bound to the carboxyl-terminal peptide of PSA. Two antibodies were found to bind to the peptide sequence adjacent to the internal cleavage site Lys145-Lys146. These antibodies failed to recognize internally cleaved PSA at Lys145-Lys146. We could not find anti-proPSA antibodies despite the fact that LNCaP PSA contained more than one-half of the zymogen form of PSA. Conclusions: We report, for the first time, novel anti-PSA antibodies that do not recognize internally cleaved PSA at Lys145-Lys146 and thus are specific for intact, unclipped PSA. (C) 2000 American Association for Clinical Chemistry.
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- Steuber, T, et al.
(författare)
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Discrimination of benign from malignant prostatic disease by selective measurements of single chain, intact free prostate specific antigen
- 2002
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Ingår i: Journal of Urology. - 1527-3792. ; 168:5, s. 1917-1922
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Free prostate specific antigen (PSA) in serum consists of heterogeneous molecular subforms. Recently we developed an immunoassay for selective measurement of a subfraction of free PSA called intact PSA, which has been shown to be closely associated with prostate cancer. We assessed the ability of serum intact PSA to discriminate between benign and malignant prostatic disease. Materials and Methods: In serum of 178 men with benign disease and 255 men with prostate cancer we measured total PSA and free PSA using a commercially available immunoassay. Intact PSA levels were analyzed by a newly developed assay specific for noncleaved, that is single chain forms of free PSA. Internally cleaved "nicked" PSA was calculated by subtracting intact from free PSA. We also calculated ratios of intact PSA-to-free PSA (intact-to-free PSA) and nicked PSA-to-total PSA (nicked-to-total PSA). We compared means, medians and ranges of all analytes and ratios in patients with and without cancer for the entire total PSA range and in a subset with total PSA ranging from 2 to 10 ng/ml. Furthermore, various combinations of PSA forms were tested for their predictive ability. For statistical comparison we used the Mann-Whitney U test and ROC analysis. Results: The ratio intact-to-free PSA was significantly higher in cancer (median 48.5%) compared to noncancer cases (median 41.8%, p <0.0001). Conversely, the ratio nicked-to-total PSA was significantly higher in men without compared to those with prostate cancer (median 11.0% and 6.0%, respectively, p <0.0001). Highest discriminative ability was observed for a combination of intact, total and free PSA (log [intact, free, total], AUC = 0.773) followed by nicked-to-total PSA (AUC 0.755). In the subgroup of patients with total PSA levels from 2 to 10 ng/ml. only the AUC of log intact, free, total (AUC 0.706, p = 0.0017) and nicked-to-total PSA (AUC 0.704, p = 0.0019) were significantly larger compared to the AUC of total PSA (AUC 0.602). Conclusions: By contrast to measuring crude free PSA concentration, selective determination of specific free PSA subforms, intact PSA and nicked PSA proved to be useful to discriminate men with benign from malignant prostatic disease. These markers may serve to generate specific serum profiles of PSA for improved specificity and early detection of prostate cancer. To translate the encouraging statistical advantage shown in this study into a clinically applicable tool warrants further investigation.
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