Proteomic analysis of patient tissue reveals PSA protein in the stroma of benign prostatic hyperplasia

The Emerging Role of Cell Adhesion Molecules on Benign Prostatic Hyperplasia

Benign prostatic hyperplasia (BPH) is a common disease in elderly men. It is characterized by prostatic enlargement and urethral compression and often causes lower urinary tract symptoms (LUTs) such as urinary frequency, urgency, and nocturia. Existing studies have shown that the pathological process of prostate hyperplasia is mainly related to the imbalance of cell proliferation and apoptosis, inflammation, epithelial-mesenchymal transition (EMT), and growth factors. However, the exact molecular mechanisms remain incompletely elucidated. Cell adhesion molecules (CAMs) are a group of cell surface proteins that mediate cell-cell adhesion and cell migration. Modulating adhesion molecule expression can regulate cell proliferation, apoptosis, EMT, and fibrotic processes, engaged in the development of prostatic hyperplasia. In this review, we went over the important roles and molecular mechanisms of cell adhesion molecules (mainly integrins and cadherins) in both physiological and pathological processes. We also analyzed the mechanisms of CAMs in prostate hyperplasia and explored the potential value of targeting CAMs as a therapeutic strategy for BPH.

Applications of Vertebrate Models in Studying Prostatitis and Inflammation-Associated Prostatic Diseases

It has long been postulated that the inflammatory environment favors cell proliferation, and is conducive to diseases such as cancer. In the prostate gland, clinical data implicate important roles of prostatitis in the progression of both benign prostatic hyperplasia (BPH) and prostate cancer (PCa). However, their causal relationships have not been firmly established yet due to unresolved molecular and cellular mechanisms. By accurately mimicking human disease, vertebrate animals provide essential in vivo models to address this question. Here, we review the vertebrate prostatitis models that have been developed and discuss how they may reveal possible mechanisms by which prostate inflammation promotes BPH and PCa. Recent studies, particularly those involving genetically engineered mouse models (GEMMs), suggest that such mechanisms are multifaceted, which include epithelium barrier disruption, DNA damage and cell proliferation induced by paracrine signals, and expansion of potential cells of origin for cancer. Future research using rodent prostatitis models should aim to distinguish the etiologies of BPH and PCa, and facilitate the development of novel clinical approaches for prostatic disease prevention.

Male Lower Urinary Tract Dysfunction: An Underrepresented Endpoint in Toxicology Research

Lower urinary tract dysfunction (LUTD) is nearly ubiquitous in men of advancing age and exerts substantial physical, mental, social, and financial costs to society. While a large body of research is focused on the molecular, genetic, and epigenetic underpinnings of the disease, little research has been dedicated to the influence of environmental chemicals on disease initiation, progression, or severity. Despite a few recent studies indicating a potential developmental origin of male LUTD linked to chemical exposures in the womb, it remains a grossly understudied endpoint in toxicology research. Therefore, we direct this review to toxicologists who are considering male LUTD as a new aspect of chemical toxicity studies. We focus on the LUTD disease process in men, as well as in the male mouse as a leading research model. To introduce the disease process, we describe the physiology of the male lower urinary tract and the cellular composition of lower urinary tract tissues. We discuss known and suspected mechanisms of male LUTD and examples of environmental chemicals acting through these mechanisms to contribute to LUTD. We also describe mouse models of LUTD and endpoints to diagnose, characterize, and quantify LUTD in men and mice.

Psoralea corylifolia L. extract ameliorates benign prostatic hyperplasia by regulating prostate cell proliferation and apoptosis

ETHNOPHARMACOLOGICAL RELEVANCE

Psoralea corylifolia L. seed (PCL), commonly known as "Poguzhi" or "BuguZhi", has been widely used to treat kidney yang deficiency in traditional Chinese medicine (TCM) where tonifying the yang deficiency is a representative understanding for treatment of hormonal deficiency disorders such as enuresis, oliguria, and prostatic diseases. Although PCL has been commonly used to treat problems of the urinary system, its efficacy against benign prostatic hyperplasia (BPH) has not yet been reported.

AIM OF THE STUDY

In the present study, we aimed to assess the in vitro and in vivo efficacy of PCL against BPH, a condition which negatively impacts quality of life in men.

MATERIALS AND METHODS

Normal human prostate cell lines, RWPE-1 and WPMY-1 cells, were stimulated with 10 nM dihydrotestosterone (DHT) to establish an in vitro BPH model. Subsequently, cells were treated with 100 or 200 μg/ml PCL, which inhibited cell proliferation without cytotoxicity, to evaluate the anti-BPH effect of PCL. Eight-week-old male Wistar rats were castrated, except for those in the control group (Con), and BPH was induced by subcutaneous injection of 10 mg/kg testosterone propionate (TP). Concurrent with daily TP injections, 5 mg/kg of finasteride (Fina) and 50 or 100 mg/kg PCL were orally administrated daily for four weeks, excluding the weekends.

RESULTS

In DHT-stimulated RWPE-1 and WPMY-1 cells, expression of androgen receptor (AR) androgen signaling-related markers such as 5α-reductase 2 (5AR2), AR, and prostate-specific antigen (PSA) was upregulated, whereas 100 or 200 μg/ml of PCL treatment downregulated these markers. Furthermore, PCL significantly reduced the mRNA expression of anti-apoptotic genes and increased the mRNA expression of pro-apoptotic gene. In vivo, administration of PCL reduced prostate size and weight in TP-induced BPH rats. Moreover, histological alterations in epithelium thickness were significantly restored by the administration of PCL. Immunohistochemical analysis revealed increased expression of AR and proliferating cell nuclear antigen (PCNA) in TP-induced BPH prostates; these changes were suppressed by administration of 50 or 100 mg/kg PCL.

CONCLUSIONS

We demonstrated the effect of PCL against BPH, mediated by the regulation of prostate cell proliferation and apoptosis, in DHT-stimulated normal human prostate cell lines and TP-induced BPH rats. These findings suggest that PCL could be a potential therapeutic agent against BPH.

E-cadherin expression is inversely correlated with aging and inflammation in the prostate

INTRODUCTION AND OBJECTIVE

Benign prostatic hyperplasia (BPH) is a prostatic disease that is significantly associated with aging. However, it is not well understood how aging contributes to BPH pathogenesis. Several factors associated with an increased risk of BPH are also associated with increasing age, including chronic inflammation and declining epithelial barrier function. Thus, this study explored the potential associations between aging, loss of adherens junction protein E-cadherin and the presence of inflammatory mediators in prostate tissue specimens from healthy young donor and BPH patients.

METHODS

Serial prostate sections from a cohort of five donors aged 15-26 years and 13 BPH patients aged 50-77 years were immunostained with E-cadherin, COX-2, CD4, CD8, CD20 and CD68. E-cadherin and COX-2 H-Scores and the number of inflammatory cells were calculated for the same area in donor, normal adjacent prostate to BPH (NAP) and BPH specimens. Quantification and statistical correlation analyses were performed for comparisons between groups.

RESULTS

E-cadherin was decreased in aged NAP tissues and in BPH compared to young donor tissue. E-cadherin was inversely correlated with age and infiltration of inflammatory cells in NAP compared to young healthy donor prostate. Stromal COX-2 was positively correlated with age and inflammation. E-cadherin was further down-regulated in BPH, while COX-2 H-Scores were not significantly altered in BPH compared to NAP.

CONCLUSIONS

These findings suggest that aging is associated with down-regulation of E-cadherin and up-regulation of stromal COX-2 immunostaining in the prostate. E-cadherin immunostaining was inversely associated with age and inflammation, while stromal COX-2 immunostaining was positively associated with age and inflammation in the prostate. These findings suggest that the prostate epithelial barrier is altered and inflammation is increased with age in the prostate. These changes are further exacerbated in BPH, and may be involved in BPH pathogenesis.

Claudin-1 down-regulation in the prostate is associated with aging and increased infiltration of inflammatory cells in BPH

INTRODUCTION AND OBJECTIVE

Benign prostatic hyperplasia (BPH) is an age-related disease that is frequently associated with chronic prostatic inflammation. In previous studies, we detected the presence of PSA protein in the stroma of BPH nodules and down-regulation of junction proteins E-cadherin and claudin-1. Transmission electron microscopy (TEM) imaging showed a decrease in tight junctions suggesting the luminal epithelial barrier in BPH tissues may be compromised. Recent in vitro studies showed that stimulation of benign prostate epithelial cell lines with TGF-β1 induced a decrease in claudin-1 expression suggesting that inflammation might be associated with alterations in the prostate epithelial barrier. This study explored the potential associations between aging and loss of junction proteins and the presence of inflammatory cells in prostate tissue specimens from young healthy donors and aged BPH patients.

METHODS

Immunostaining of serial prostate sections from 13 BPH patients and five healthy young donors was performed for claudin-1, CD4, CD8, CD20 and CD68. H-Scores and the number of inflammatory cells were calculated for the same area in donor, normal adjacent prostate (NAP) to and BPH specimens. Quantification and statistical correlation analyses were performed.

RESULTS

Claudin-1 immunostaining was inversely associated with increasing age, and inflammation in prostate specimens. B-cell infiltration increased with age and BPH was associated with an increased infiltration of T-cells and macrophages compared to NAP.

CONCLUSIONS

These findings suggest that aging is associated with down-regulation of claudin-1 and claudin-1 is further decreased in BPH. Claudin-1 down-regulation was associated with increased infiltration of inflammatory cells in both NAP and BPH tissues. Claudin-1 down-regulation in the aging prostate could contribute to increased prostatic inflammation, subsequently contributing to BPH pathogenesis.

Discovering pathways in benign prostate hyperplasia: A functional genomics pilot study

Benign prostate hyperplasia (BPH) is one of the well-known urological neoplasms common in males with an increasing number of associated deaths in aging males. It causes uncomfortable urinary symptoms, including urine flow blockage, and may cause bladder, urinary tract or kidney problems. The histopathological and clinical knowledge regarding BPH is limited. In the present study, an in silico approach was applied that uses genome-scale microarray expression data to discover a wide range of protein-protein interactions in addition to focusing on specific genes responsible for BPH to develop prognostic biomarkers. Various genes that were differentially expressed in BPH were identified. Gene and functional annotation clusters were determined and an interaction analysis with disease phenotypes of BPH was performed, as well as an RNA tissue specificity analysis. Furthermore, a molecular docking study of certain short-listed gene biomarkers, namely anterior gradient 2 (AGR2; PDB ID: 2LNT), steroid 5α-reductase 2 (PDB ID: 6OQX), zinc finger protein 3 (PDB ID: 5T00) and collagen type XII α1 chain (PDB ID: 1U5M), was performed in order to identify alternative Chinese herbal agents for the treatment of BPH. Data from the present study revealed that AGR2 receptor (PDB ID: 2LNT) and berberine (Huang Bo) form the most stable complex and therefore may be assessed in further pharmacological studies for the treatment of BPH.

Prostate-Specific Deletion of Cdh1 Induces Murine Prostatic Inflammation and Bladder Overactivity

Benign prostatic hyperplasia (BPH) is an age-related debilitating prostatic disease that is frequently associated with prostatic inflammation and bothersome lower urinary tract symptoms (LUTS). Animal models have shown that formalin- and bacterial-induced prostatic inflammation can induce bladder dysfunction; however, the underlying mechanisms contributing to prostatic inflammation in BPH and bladder dysfunction are not clear. We previously reported that E-cadherin expression in BPH is downregulated in hyperplastic nodules compared with expression in adjacent normal tissues. Here, we explored the potential consequences of prostatic E-cadherin downregulation on the prostate and bladder in vivo using an inducible murine model of prostate luminal epithelial-specific deletion of Cdh1. The prostate-specific antigen (PSA)-CreERT2 transgenic mouse strain expressing tamoxifen-inducible CreERT2 recombinase driven by a 6-kb human PSA promoter/enhancer was crossed with the B6.129-Cdh1tm2Kem/J mouse to generate bigenic PSA-CreERT2/Cdh1-/- mice. Deletion of E-cadherin was induced by transient administration of tamoxifen when mice reached sexual maturity (7 weeks of age). At 21 to 23 weeks of age, the prostate, bladder, and prostatic urethra were examined histologically, and bladder function was assessed using void spot assays and cystometry. Mice with Cdh1 deletion had increased prostatic inflammation, prostatic epithelial hyperplasia, and stromal changes at 21 to 23 weeks of age, as well as changes in bladder voiding function compared with age-matched controls. Thus, loss of E-cadherin in the murine prostate could result in prostatic defects that are characteristic of BPH and LUTS, suggesting that E-cadherin downregulation could be a driving force in human BPH development and progression.

Abnormal expression of Rab27B in prostatic epithelial cells of benign prostatic hyperplasia alters intercellular communication

Abnormal intraglandular stromal-epithelial interactions have been known as a main key contributing factor for development of Benign Prostatic Hyperplasia (BPH). However, the underlying mechanism for the dysregulated intercellular communication remains unclear. In this study we compared the proteomic profiles of hyperplastic tissue with adjacent normal tissue of BPH and identified Rab27B small GTPase, a key regulator of exocytosis, as a protein that was overexpressed in the epithelium of BPH tissue. Overexpression of Rab27B in prostatic epithelial cells strongly increased the signaling activities of the PI3K/AKT and ERK1/2 pathways, whereas, downregulation of Rab27B expression in the epithelial cells of BPH reduced the signaling activities and decreased cell proliferation. The elevated Rab27B expression caused an overall increase in cell surface presentation of growth factor receptors without affecting their expression. However, the small GTPase also possesses an inhibitory activity against mTORC1 independent of its role in cell surface presentation of growth factor receptors. Our findings demonstrate a pivotal role of the small GTPase in autocrine and paracrine signaling and suggest that its abnormal expression underlies the dysregulated stromal-epithelial interactions in BPH.

Tight junction protein claudin-1 is downregulated by TGF-β1 via MEK signaling in benign prostatic epithelial cells

BACKGROUND

Benign prostatic hyperplasia (BPH) is arguably the most common disease in aging men. Although the etiology is not well understood, chronic prostatic inflammation is thought to play an important role in BPH initiation and progression. Our recent studies suggest that the prostatic epithelial barrier is compromised in glandular BPH tissues. The proinflammatory cytokine transforming growth factor beta 1 (TGF-β1) impacts tight junction formation, enhances epithelial barrier permeability, and suppresses claudin-1 messenger RNA expression in prostatic epithelial cells. However, the role of claudin-1 in the prostatic epithelial barrier and its regulation by TGF-β1 in prostatic epithelial cells are not clear.

METHODS

The expression of claudin-1 was analyzed in 22 clinical BPH specimens by immunohistochemistry. Human benign prostate epithelial cell lines BPH-1 and BHPrE1 were treated with TGF-β1 and transfected with small interfering RNAs specific to claudin-1. Epithelial monolayer permeability changes in the treated cells were measured using trans-epithelial electrical resistance (TEER). The expression of claudin-1, E-cadherin, N-cadherin, snail, slug, and activation of mitogen-activated proteins kinases (MAPKs) and AKT was assessed following TGF-β1 treatment using Western blot analysis.

RESULTS

Claudin-1 expression was decreased in glandular BPH tissue compared with adjacent normal prostatic tissue in patient specimens. TGF-β1 treatment or claudin-1 knockdown in prostatic epithelial cell lines increased monolayer permeability. TGF-β1 decreased levels of claudin-1 and increased levels of snail and slug as well as increased phosphorylation of the MAPK extracellular signal-regulated kinase-1/2 (ERK-1/2) in both BPH-1 and BHPrE1 cells. Overexpression of snail or slug had no effect on claudin-1 expression. In contrast, PD98059 and U0126, inhibitors of the upstream activator of ERK-1/2 (ie, MEK-1/2) restored claudin-1 expression level as well as the epithelial barrier.

CONCLUSION

Our findings suggest that downregulation of claudin-1 by TGF-β1 acting through the noncanonical MEK-1/2/ERK-1/2 pathway triggers increased prostatic epithelial monolayer permeability in vitro. These findings also suggest that elevated TGF-β1 may contribute to claudin-1 downregulation and compromised epithelial barrier in clinical BPH specimens.

Transforming growth factor beta 1 impairs benign prostatic luminal epithelial cell monolayer barrier function

Our recent studies identifying the presence of luminal secretory protein PSA in the stroma, decreased E-cadherin expression, and reduced number of tight junction kiss points in benign prostatic hyperplasia (BPH) tissues suggest that epithelial barrier permeability is increased in BPH. However, the cause of increased epithelial permeability in BPH is unclear. Transforming growth factor beta 1 (TGF-β1) has been reported to be up-regulated in clinical BPH specimens and TGF-β1 overexpression induced fibrosis and inflammation in a murine model. TGF-β1 was reported to repress the expression of E-cadherin in benign prostatic cells. However, whether and how TGF-β1 up-regulation affects epithelial barrier permeability is unknown. Here, in vitro benign prostatic epithelial cell lines BHPrE1 and BPH-1 were utilized to determine the impact of TGF-β1 treatment on epithelial barrier, tight junctions, and expression of E-cadherin and claudin 1 by transepithelial electrical resistance (TEER) measurement, FITC-dextran trans-well diffusion assays, qPCR, as well as transmission electron microscopy (TEM) observation. Laser capture micro-dissection (LCM) combined with reverse transcription-polymerase chain reaction (qPCR) were utilized to determine the expression of E-cadherin and claudin 1 in BPH patient specimens. TGF-β1 treatment decreased TEER, increased FITC-dextran diffusion, and reduced the mRNA expression of junction protein claudin 1 in cultured cell monolayers. Claudin 1 mRNA but not E-cadherin mRNA was down-regulated in the luminal epithelial cells in BPH nodules compared to normal prostate tissues. Our studies suggest that TGF-β1 could increase the permeability through decreasing the expression of claudin 1 and inhibiting the formation of tight junctions in BHPrE1 and BPH-1 monolayers. These results suggest that TGF-β1 might play an important role in BPH pathogenesis through increasing the permeability of luminal epithelial barrier in the prostate.

Comparison of CD34 expression in fibrous reactive hyperplasia and healthy oral mucosa

OBJECTIVES

Fibrous reactive hyperplasia (FRH) is a common fibrous lesion in the oral cavity. The disease characteristics of FRH, including the expression patterns of CD34, which is a well-known fibroblast marker, have not been investigated in detail. Therefore, in this study, we aimed to investigate the characteristics of FRH compared to those of the healthy mucosa, based on CD34 expression profiles.

METHODS

CD34 expression was analyzed at the protein and mRNA levels using immunohistochemistry, quantitative polymerase chain reaction, and in situ hybridization (ISH).

RESULTS

CD34 was not expressed in the lamina propria of the oral mucosa, but was commonly observed in submucosal fibroblasts. CD34-positive fibroblasts were commonly observed in FRH. A total of 17 out of 19 cases (89.5%) were CD34-positive. Furthermore, we identified a significant difference in the ratio of CD34-positive cells between the healthy and FRH tissues. Quantitative polymerase chain reaction showed that CD34 mRNA was expressed in all cases of FRH, and CD34 mRNA expression in FRH samples was found to be localized to spindle-shaped fibroblasts, as determined by ISH. A positive correlation was also found between the CD34 mRNA levels and the proportion of the CD34-positive cells.

CONCLUSIONS

These findings suggest that the increase in collagen synthesis in CD34-positive fibroblasts in the submucosa leads to the development of FRH. To our knowledge, this is the first report confirming the mRNA expression patterns of CD34 in FRH.

Mesenchymal stem cells and the embryonic reawakening theory of BPH

The prostate is the only organ in a man that continues to grow with age. John McNeal proposed, 40 years ago, that this BPH is characterized by an age-related reinitiation of benign neoplastic growth selectively in developmentally abortive distal ducts within the prostate transition-periurethral zone (TPZ), owing to a reawakening of inductive stroma selectively within these zones. An innovative variant of this hypothesis is that, owing to its location, the TPZ is continuously exposed to urinary components and/or autoantigens, which produces an inflammatory TPZ microenvironment that promotes recruitment of bone marrow-derived mesenchymal stem cells (MSCs) and generates a paracrine-inductive stroma that reinitiates benign neoplastic nodular growth. In support of this hypothesis, MSCs infiltrate human BPH tissue and have the ability to stimulate epithelial stem cell growth. These results provide a framework for defining both the aetiology of BPH in ageing men and insights into new therapeutic approaches.

E-cadherin is downregulated in benign prostatic hyperplasia and required for tight junction formation and permeability barrier in the prostatic epithelial cell monolayer

BACKGROUND

We previously reported the presence of prostate-specific antigen (PSA) in the stromal compartment of benign prostatic hyperplasia (BPH). Since PSA is expressed exclusively by prostatic luminal epithelial cells, PSA in the BPH stroma suggests increased tissue permeability and the compromise of epithelial barrier integrity. E-cadherin, an important adherens junction component and tight junction regulator, is known to exhibit downregulation in BPH. These observations suggest that the prostate epithelial barrier is disrupted in BPH and E-cadherin downregulation may increase epithelial barrier permeability.

METHODS

The ultra-structure of cellular junctions in BPH specimens was observed using transmission electron microscopy (TEM) and E-cadherin immunostaining analysis was performed on BPH and normal adjacent specimens from BPH patients. In vitro cell line studies using benign prostatic epithelial cell lines were performed to determine the impact of small interfering RNA knockdown of E-cadherin on transepithelial electrical resistance and diffusion of fluorescein isothiocyanate (FITC)-dextran in transwell assays.

RESULTS

The number of kiss points in tight junctions was reduced in BPH epithelial cells as compared with the normal adjacent prostate. Immunostaining confirmed E-cadherin downregulation and revealed a discontinuous E-cadherin staining pattern in BPH specimens. E-cadherin knockdown increased monolayer permeability and disrupted tight junction formation without affecting cell density.

CONCLUSIONS

Our results indicate that tight junctions are compromised in BPH and loss of E-cadherin is potentially an important underlying mechanism, suggesting targeting E-cadherin loss could be a potential approach to prevent or treat BPH.

In-Depth Characterization and Validation of Human Urine Metabolomes Reveal Novel Metabolic Signatures of Lower Urinary Tract Symptoms

Lower urinary tract symptoms (LUTS) are a range of irritative or obstructive symptoms that commonly afflict aging population. The diagnosis is mostly based on patient-reported symptoms, and current medication often fails to completely eliminate these symptoms. There is a pressing need for objective non-invasive approaches to measure symptoms and understand disease mechanisms. We developed an in-depth workflow combining urine metabolomics analysis and machine learning bioinformatics to characterize metabolic alterations and support objective diagnosis of LUTS. Machine learning feature selection and statistical tests were combined to identify candidate biomarkers, which were statistically validated with leave-one-patient-out cross-validation and absolutely quantified by selected reaction monitoring assay. Receiver operating characteristic analysis showed highly-accurate prediction power of candidate biomarkers to stratify patients into disease or non-diseased categories. The key metabolites and pathways may be possibly correlated with smooth muscle tone changes, increased collagen content, and inflammation, which have been identified as potential contributors to urinary dysfunction in humans and rodents. Periurethral tissue staining revealed a significant increase in collagen content and tissue stiffness in men with LUTS. Together, our study provides the first characterization and validation of LUTS urinary metabolites and pathways to support the future development of a urine-based diagnostic test for LUTS.

Diagnostic, prognostic and predictive value of cell-free miRNAs in prostate cancer: a systematic review

Prostate cancer, the second most frequently diagnosed cancer in males worldwide, is estimated to be diagnosed in 1.1 million men per year. Introduction of PSA testing substantially improved early detection of prostate cancer, however it also led to overdiagnosis and subsequent overtreatment of patients with an indolent disease. Treatment outcome and management of prostate cancer could be improved by the development of non-invasive biomarker assays that aid in increasing the sensitivity and specificity of prostate cancer screening, help to distinguish aggressive from indolent disease and guide therapeutic decisions. Prostate cancer cells release miRNAs into the bloodstream, where they exist incorporated into ribonucleoprotein complexes or extracellular vesicles. Later, cell-free miRNAs have been found in various other biofluids. The initial RNA sequencing studies suggested that most of the circulating cell-free miRNAs in healthy individuals are derived from blood cells, while specific disease-associated miRNA signatures may appear in the circulation of patients affected with various diseases, including cancer. This raised a hope that cell-free miRNAs may serve as non-invasive biomarkers for prostate cancer. Indeed, a number of cell-free miRNAs that potentially may serve as diagnostic, prognostic or predictive biomarkers have been discovered in blood or other biofluids of prostate cancer patients and need to be validated in appropriately designed longitudinal studies and clinical trials. In this review, we systematically summarise studies investigating cell-free miRNAs in biofluids of prostate cancer patients and discuss the utility of the identified biomarkers in various clinical scenarios. Furthermore, we discuss the possible mechanisms of miRNA release into biofluids and outline the biological questions and technical challenges that have arisen from these studies.

Involvement of Kallikrein-Related Peptidases in Normal and Pathologic Processes

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 on their involvement in different processes related to health and disease, in particular those directly or indirectly linked to the neoplastic process.