Down-regulation of kallikrein-related peptidase 5 (KLK5) expression in breast cancer patients: a biomarker for the differential diagnosis of breast lesions (original) (raw)
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Tissue kallikrein-related peptidase 4 (KLK4), a novel biomarker in triple-negative breast cancer
Biological chemistry, 2017
Triple-negative breast cancer (TNBC), lacking the steroid hormone receptors ER and PR and the oncoprotein HER2, is characterized by its aggressive pattern and insensitivity to endocrine and HER2-directed therapy. Human kallikrein-related peptidases KLK1-15 provide a rich source of serine protease-type biomarkers associated with tumor growth and cancer progression for a variety of malignant diseases. In this study, recombinant KLK4 protein was generated and affinity-purified KLK4-directed polyclonal antibody pAb587 established to allow localization of KLK4 protein expression in tumor cell lines and archived formalin-fixed, paraffin-embedded TNBC tumor tissue specimens. For this, KLK4 protein expression was assessed by immunohistochemistry in primary tumor tissue sections (tissue microarrays) of 188 TNBC patients, mainly treated with anthracycline- or CMF-based polychemotherapy. KLK4 protein is localized in the cytoplasm of tumor and stroma cells. In this patient cohort, elevated stro...
Utility of Kallikrein-Related Peptidases (KLKs) as Cancer Biomarkers
Clinical Chemistry, 2008
Background: The human kallikrein-related peptidase (KLK) family consists of 15 highly conserved serine proteases, which are encoded by the largest uninterrupted cluster of protease genes in the human genome. To date, several members of the family have been reported as potential cancer biomarkers. Although primarily known for their biomarker value in prostate, ovarian, and breast cancers, more recent data suggest analogous roles of KLKs in several other cancers, including gastrointestinal, head and neck, lung, and brain malignancies. Among the proposed KLK cancer biomarkers, prostate-specific antigen (also known as KLK3) is the most widely recognized member in urologic oncology. Content: Despite substantial progress in the understanding of the biomarker utility of individual KLKs, the current challenge lies in devising biomarker panels to increase the accuracy of prognosis, prediction of therapy, and diagnosis. To date, multiparametric KLK panels have been proposed for prostate, ovar...
Clinical and Experimental Medicine, 2018
Novel molecular markers that address the heterogeneity of breast cancer (BC) and provide meaningful prognostic information for BC patients are needed. Kallikrein-related peptidase 6 (KLK6) is aberrantly expressed and functionally implicated in BC and, like other members of the KLK family, may prove a useful molecular tool for clinical management. Our objective was to assess, for the first time, the clinical relevance of KLK6 mRNA expression in BC. Total RNA was isolated from 165 breast tumors, as well as 100 adjacent non-cancerous tumor specimens. After cDNA synthesis, and following quality control, quantitative real-time PCR for KLK6 expression analysis took place. Receiver operating characteristic curves were constructed in order to assess the ability of KLK6 mRNA expression levels to differentiate between molecular BC subtypes. Survival analyses, using DFS as endpoint, were performed at the univariate and multivariate levels. Publicly available BC databases and online survival analysis tools were used to validate our findings. A significant downregulation of KLK6 mRNA expression was observed in BC tissue sections compared to the non-cancerous component (P < 0.001). The expression of KLK6 is positively associated with tumor grade (P = 0.038) and is overexpressed in TNBC and HER2-positive tumors (P < 0.001). Aberrant KLK6 expression predicts the clinical outcome of BC patients in terms of DFS, independently of currently used prognostic markers (HR = 7.11, 95% CI = 1.19-42.45). The differential expression of KLK6 and its association with unfavorable outcome in BC patients was validated via in silico analyses. Although an independent external cohort is necessary to confirm our findings, we proved for the first time that KLK6 can provide independent prognostic information for BC patients.
Biological Chemistry, 2010
KLK4 is a member of the human kallikrein-related peptidase family of (chymo)trypsin-like serine proteases. The aim of the present study was to generate polyclonal antibodies (pAb) directed against KLK4 for the analysis of KLK4 by immunohistochemistry in human tissues. Recombinantly expressed human mature KLK4 was used for immunization of chickens. pAb 617A is an affinity-purified monospecific pAb fraction reacting with a linear epitope within a flexible surface-exposed loop of KLK4. pAb 617C is the KLK-directed pAb fraction completely depleted from pAb 617A. In healthy adult tissues, KLK4 was immunodetected by both antibody fractions in kidney, liver, and prostate, but not in other organs such as colon and lung. To evaluate protein expression of KLK4 in prostate cancer, samples of tumor tissue plus corresponding tumor-free areas of 44 prostate cancer patients, represented on a tissue microarray, were investigated. Distinct KLK4 immunostaining was observed with both antibodies in can...
Upregulation and secretion of kallikrein-related peptidase 6 (KLK6) in gastric cancer
Tumor Biology, 2012
KLK6 encoding kallikrein-related peptidase 6, a trypsin-like serine protease, has been shown to be upregulated in several cancers, although the tumorigenic role of KLK6 has not been elucidated. In this study, KLK6 was identified as a highly upregulated gene in gastric cancer; therefore, the possibility that KLK6 might be a suitable candidate tumor marker was examined. RT-PCR and immunohistochemical analysis showed overexpression of KLK6 in gastric cancer tissues compared to nontumor regions. Sera from gastric cancer patients had a 1.7-fold increase in KLK6 (373.1 μg/L, P=0.048) compared to healthy individuals (214.2 μg/L), although there was no significant difference among patients with various tumor stages. Cellular invasiveness decreased by 45% in cells transfected with KLK6-specific small interfering RNA. Exogenous overexpression of KLK6 led to decreased activity of the E-cadherin promoter. This study shows that KLK6 is significantly upregulated and secreted in gastric cancer tissues and sera, suggesting that KLK6 might be used as a potential biomarker and therapeutic target for gastric cancer.
Enzymatic properties of human kallikrein-related peptidase 12 (KLK12)
Biological Chemistry, 2000
Human kallikrein-related peptidase 12 (KLK12) is a new member of the human tissue kallikrein family. Preliminary studies suggest that KLK12 is differentially expressed in breast cancer and may have potential use as a cancer biomarker. It has been predicted that KLK12 is a secreted serine protease. However, the enzymatic properties of this protein have not been reported so far. Here, we report the production of recombinant KLK12 and analyses of its enzymatic characteristics, including zymogen activation, substrate specificity, and regulation of its activity. KLK12 is secreted as an inactive pro-enzyme, which is able to autoactivate to gain enzymatic activity. Through screening of a panel of fluorogenic and chromogenic peptide substrates, we establish that active KLK12 possesses trypsin-like activity, cleaving peptide bonds after both arginine and lysine. Active KLK12 quickly loses its activity due to autodegradation, and its activity can also be rapidly inhibited by zinc ions and by a 2-antiplasmin through covalent complex formation. Furthermore, we demonstrate that KLK12 is able to activate KLK11 zymogen in vitro. Our results indicate that KLK12 may participate in enzymatic cascades involving other kallikreins.
Anticancer research, 2014
The sera of patients with breast cancer have higher levels of des[Arg(9)]bradykinin, a kinin B1 receptor (B1R) agonist, than that from healthy individuals. Stimulation of breast cancer cells with the analog Lys-des[Arg(9)]bradykinin causes release of metalloproteinases-2 and -9 and increases cell proliferation. We examined the possibility that breast cancer cells, in addition to B1R, express the kinin-forming protease true tissue kallikrein (KLK1) and the endogenous proteins termed kininogens from which kinins are enzymatically released. Furthermore, we investigated whether stimulation of breast cancer cells with a B1R agonist would modify the cellular levels of KLK6, KLK10 and KLK11, three kallikrein-related peptidases with a still poorly-understood biological role in breast cancer. We found that breast cancer cells expressed KLK1 and kininogens, and that stimulation of estrogen-sensitive breast cancer cells with the B1R agonist produced down-regulation of KLK10 (a protease associa...
Cancer Research, 2009
Human kallikrein-related peptidase 6 (KLK6) was cloned as a putative class II tumor suppressor based on its inactivated expression in metastatic breast cancer. Here, we investigated the mechanism(s) underlying the silencing of KLK6 gene in metastatic breast cancer and its putative implications for tumor progression. We present evidence that tumor-specific loss of KLK6 expression is due to hypermethylation of specific CpGs located in the KLK6 proximal promoter. Methylationdependent binding of methyl CpG-binding protein 2 and the formation of repressive chromatin mediated by localized histone deacetylation are critical components of KLK6 silencing in breast tumors. Re-expression of KLK6 in nonexpressing MDA-MB-231 breast tumor cells by stable cDNA transfection resulted in marked reversal of their malignant phenotype, manifested by lower proliferation rates and saturation density, marked inhibition of anchorage-independent growth, reduced cell motility, and their dramatically reduced ability to form tumors when implanted in severe combined immunodeficiency mice. Interestingly, inhibition of tumor growth was observed at physiologic concentrations of KLK6, but not when KLK6 was highly overexpressed, as observed in a subset of breast tumors. Differential proteomic profiling revealed that KLK6 re-expression results in significant down-regulation of vimentin which represents an established marker of epithelial-to-mesenchymal transition of tumor cells and in concomitant up-regulation of calreticulin and epithelial markers cytokeratin 8 and 19, indicating that KLK6 may play a protective role against tumor progression that is likely mediated by inhibition of epithelial-to-mesenchymal transition. We suggest that KLK6 is an epigenetically regulated tumor suppressor in human breast cancer and provide ways of pharmacologic modulation. [Cancer Res 2009;69(9):3779-87]
Involvement of Kallikrein-Related Peptidases in Normal and Pathologic Processes
Disease Markers, 2015
Human kallikrein-related peptidases (KLKs) are a subgroup of serine proteases that participate in proteolytic pathways and control protein levels in normal physiology as well as in several pathological conditions. Their complex network of stimulatory and inhibitory interactions may induce inflammatory and immune responses and contribute to the neoplastic phenotype through the regulation of several cellular processes, such as proliferation, survival, migration, and invasion. This family of proteases, which includes one of the most useful cancer biomarkers, kallikrein-related peptidase 3 or PSA, also has a protective effect against cancer promoting apoptosis or counteracting angiogenesis and cell proliferation. Therefore, they represent attractive therapeutic targets and may have important applications in clinical oncology. Despite being intensively studied, many gaps in our knowledge on several molecular aspects of KLK functions still exist. This review aims to summarize recent data ...
Radiology and oncology, 2013
Tumor tissue-associated KLKs (kallikrein-related peptidases) are clinically important biomarkers that may allow prognosis of the cancer disease and/or prediction of response/failure of cancer patients to cancer-directed drugs. Regarding the female/male reproductive tract, remarkably, all of the fifteen KLKs are expressed in the normal prostate, breast, cervix uteri, and the testis, whereas the uterus/endometrium and the ovary are expressing a limited number of KLKs only. Most of the information regarding elevated expression of KLKs in tumor-affected organs is available for ovarian cancer; depicting them as valuable biomarkers in the cancerous phenotype. In contrast, for breast cancer, a series of KLKs was found to be downregulated. However, in breast cancer, KLK4 is elevated which is also true for ovarian and prostate cancer. In such cases, selective synthetic KLK inhibitors that aim at blocking the proteolytic activities of certain KLKs may serve as future candidate therapeutic dru...