Human Kallikrein 4: Quantitative Study in Tissues and Evidence for Its Secretion into Biological Fluids
Open Access
- 1 August 2005
- journal article
- Published by Oxford University Press (OUP) in Clinical Chemistry
- Vol. 51 (8) , 1432-1442
- https://doi.org/10.1373/clinchem.2005.049692
Abstract
Background: Human kallikrein 4 (hK4) is a proteolytic enzyme belonging to the tissue kallikrein family of serine proteases. Previous tissue expression studies have demonstrated highest KLK4 mRNA expression in prostatic tissue, but there has been only limited evidence for the presence of hK4 protein in prostate and other tissues and in corresponding biological secretions. Methods: To investigate the concentrations of hK4 in tissues and biological fluids, we developed a new hK4-specific sandwich-type immunoassay using a monoclonal antibody as the capture reagent. Results: The assay has a detection limit of 0.02 μg/L and <0.1% cross-reactivity toward any of the other 14 human kallikreins. Twelve of 40 tissue extracts prepared from various human tissues contained detectable hK4 concentrations (0.68–7143 ng/g of total protein), with healthy prostate tissue containing the highest amount of hK4. Examination of 16 malignant and 18 benign prostate tissues revealed no significant differences in hK4 protein content, and the tissues contained a wide range of values (benign, <0.02 to 801 ng/g; malignant, <0.02 to 824 ng/g). Among the biological fluids tested, seminal plasma and urine contained widely varying amounts of hK4; concentrations in 54 urine samples were <0.02 to 2.6 μg/L, whereas concentrations in 58 seminal plasma samples were 0.2–202 μg/L. Affinity purification of hK4 from seminal plasma and subsequent mass spectrometry demonstrated the secreted nature of hK4 in seminal plasma. Conclusions: hK4 is found primarily in prostate tissue and is secreted in seminal plasma. Its value as a novel prostatic biomarker needs to be defined further.Keywords
This publication has 42 references indexed in Scilit:
- Kallikrein 4 Is a Secreted ProteinCancer Research, 2004
- Reference distributions for α2‐macroglobulin: A comparison of a large cohort to the world's literatureJournal of Clinical Laboratory Analysis, 2004
- Novel ENAM mutation responsible for autosomal recessive amelogenesis imperfecta and localised enamel defectsJournal of Medical Genetics, 2003
- Expression and Localization of Tissue Kallikrein mRNAs in Human Epidermis and AppendagesJournal of Investigative Dermatology, 2003
- Characterization of KLK4 expression and detection of KLK4-specific antibody in prostate cancer patient seraOncogene, 2002
- Distinctly Different Gene Structure ofKLK4/KLK-L1/Prostase/ARM1 Compared with Other Members of the Kallikrein Family: Intracellular Localization, Alternative cDNA Forms, and Regulation by Multiple HormonesDNA and Cell Biology, 2001
- Kallikrein 4 (KLK4), A New Member of the Human Kallikrein Gene Family Is Up-Regulated By Estrogen and Progesterone in the Human Endometrial Cancer Cell Line, KLEJournal of Clinical Endocrinology & Metabolism, 2001
- Localization of a New Prostate-specific Antigen-related Serine Protease Gene, KLK4 , Is Evidence for an Expanded Human Kallikrein Gene Family Cluster on Chromosome 19q13.3–13.4Journal of Biological Chemistry, 1999
- Human glandular kallikrein, hK2, shows arginine-restricted specificity and forms complexes with plasma protease inhibitorsThe Prostate, 1998
- Enzymatic activity of prostate‐specific antigen and its reactions with extracellular serine proteinase inhibitorsEuropean Journal of Biochemistry, 1990