Human kallikrein 2 (hK2), but not prostate‐specific antigen (PSA), rapidly complexes with protease inhibitor 6 (PI‐6) released from prostate carcinoma cells

Saedi, Mohammad S.; Zhu, Zhu; Marker, Kathy M.; Liu, Ru-Shya; Carpenter, Philip M.; Rittenhouse, Harry G.; Mikolajczyk, Stephen D.

doi:10.1002/ijc.1501

Cited by 25 publications

(16 citation statements)

References 25 publications

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“…The formation of these heterocomplexes [25] could effectively mask KLK9 epitopes. This has been observed with many other kallikreins, including PSA [24, 26, 27]. …”

Section: Discussionsupporting

confidence: 59%

A new enzyme-linked immunosorbent assay (ELISA) for human free and bound kallikrein 9

et al. 2017

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BackgroundKallikrein 9 (KLK9) is a member of the human kallikrein-related peptidases family, whose physiological role and implications in disease processes remain unclear. The active form of the enzyme is predicted to have chymotryptic activity. In the present study, we produced for the first time the active recombinant protein and monoclonal antibodies, and developed novel immunoassays for the quantification of free and bound KLK9 in biological samples.MethodsThe coding sequence of mature KLK9 isoform (mat-KLK9) was expressed in an Expi293F mammalian system and the synthesized polypeptide was purified through a two-step protocol. The purified protein was used as an immunogen for production of monoclonal antibodies in mice. Hybridomas were further expanded and antibodies were purified. Newly-produced monoclonal antibodies were screened for reaction with the KLK9 recombinant protein by a state-of-the-art immunocapture/parallel reaction monitoring mass spectrometry-based methodology.ResultsAnti-KLK9 antibodies were combined in pairs, resulting in the development of a highly sensitive (limit of detection: 15 pg/mL) and specific (no cross-reactivity with other KLKs) sandwich-type ELISA. Highest KLK9 protein levels were found in tonsil and sweat and lower levels in the heart, kidney and liver. Hybrid immunoassays using an anti-KLK9 antibody for antigen capture and various anti-serine protease inhibitor polyclonal antibodies, revealed the presence of an a1-antichymotrypsin-bound KLK9 isoform in biological samples.ConclusionsThe ELISAs for free and bound forms of KLK9 may be highly useful for the detection of KLK9 in a broad range of biological samples, thus enabling the clarification of KLK9 function and use as a potential disease biomarker.Electronic supplementary materialThe online version of this article (doi:10.1186/s12014-017-9140-6) contains supplementary material, which is available to authorized users.

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“…The formation of these heterocomplexes [25] could effectively mask KLK9 epitopes. This has been observed with many other kallikreins, including PSA [24, 26, 27]. …”

Section: Discussionsupporting

confidence: 59%

A new enzyme-linked immunosorbent assay (ELISA) for human free and bound kallikrein 9

et al. 2017

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“…SERPINB6 also is detected in a complex with kallikrein 2 in extracts from prostate cancer cells and, to a lesser extent, normal prostate tissue [114]. This complex appears to occur in the extracellular space after cell lysis and is not found in the seminal plasma [115]. This complex may serve as a marker for the tissue damage associated with prostate cancer.…”

Section: Serpinb6 (Placental Thrombin Inhibitor Cytoplasmic Antiprotmentioning

confidence: 99%

Human clade B serpins (ov-serpins) belong to a cohort of evolutionarily dispersed intracellular proteinase inhibitor clades that protect cells from promiscuous proteolysis

Silverman

Whisstock

Askew

et al. 2004

Cellular and Molecular Life Sciences (CMLS)

161

164

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Serpins are unique among the various types of active site proteinase inhibitors because they covalently trap their targets by undergoing an irreversible conformational rearrangement. Members of the serpin superfamily are present in the three major domains of life (Bacteria, Archaea and Eukarya) as well as several eukaryotic viruses. The human genome encodes for at least 35 members that segregate evolutionarily into nine (A-I) distinct clades. Most of the human serpins are secreted and circulate in the bloodstream where they reside at critical checkpoints intersecting self-perpetuating proteolytic cascades such as those of the clotting, thrombolytic and complement systems. Unlike these circulating serpins, the clade B serpins (ov-serpins) lack signal peptides and reside primarily within cells. Most of the human clade B serpins inhibit serine and/or papain-like cysteine proteinases and protect cells from exogenous and endogenous proteinase-mediated injury. Moreover, as sequencing projects expand to the genomes of other species, it has become apparent that intracellular serpins belonging to distinct phylogenic clades are also present in the three major domains of life. As some of these serpins also guard cells against the deleterious effects of promiscuous proteolytic activity, we propose that this cytoprotective function, along with similarities in structure are common features of a cohort of intracellular serpin clades from a wide variety of species.

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“…Human kallikrein 2 (KLK2), a possible serum marker for PCa may play a role in cancer progression and metastasis [140]. KLK2 is a secreted trypsin like protease, localized to prostatic epithelium that shares the exact 80% amino acid sequence with PSA and possibly activates and regulates PSA [141].…”

Section: Current and Emerging Biomarkersmentioning

confidence: 99%

Current Status of Biomarkers for Prostate Cancer

Velonas

Woo

Remedios

et al. 2013

IJMS

197

152

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Prostate cancer (PCa) is a leading cause of cancer-related death of men globally. Since its introduction, there has been intense debate as to the effectiveness of the prostate specific antigen (PSA) test as a screening tool for PCa. It is now evident that the PSA test produces unacceptably high rates of false positive results and is not prognostic. Here we review the current status of molecular biomarkers that promise to be prognostic and that might inform individual patient management. It highlights current efforts to identify biomarkers obtained by minimally invasive methods and discusses current knowledge with regard to gene fusions, mRNA and microRNAs, immunology, and cancer-associated microparticles.

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Human kallikrein 2 (hK2), but not prostate‐specific antigen (PSA), rapidly complexes with protease inhibitor 6 (PI‐6) released from prostate carcinoma cells

Cited by 25 publications

References 25 publications

A new enzyme-linked immunosorbent assay (ELISA) for human free and bound kallikrein 9

A new enzyme-linked immunosorbent assay (ELISA) for human free and bound kallikrein 9

Human clade B serpins (ov-serpins) belong to a cohort of evolutionarily dispersed intracellular proteinase inhibitor clades that protect cells from promiscuous proteolysis

Current Status of Biomarkers for Prostate Cancer

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