Urokinase and urokinase receptor: a paracrine/autocrine system regulating cell migration and invasiveness

Decreased fertility in female mice lacking urokinase plasminogen activator

It is well established that mouse ovarian granulosa cells secrete urokinase plasminogen activator (uPA) under gonadotropin stimulation. The synthesis and secretion of the enzyme correlate well with the time of follicular rupture in vivo. Moreover, uPA is secreted by the trophoblast at the time of implantation. In the present study, we have analyzed whether the absence of uPA could influence follicular growth, ovulation, and embryo implantation. Our data show fewer preantral follicles in uPA-/- ovaries but no decrease in hormonally induced ovulation. However, we observed a significant decrease in the number of implanted embryos in uPA-/- animals and, therefore, a lower number of pups per family. Adding uPA to the epithelial and stromal uterine cell culture medium strongly upregulates the expression of prostaglandin-endoperoxide synthase 2 (Ptgs2), the enzyme required for prostaglandin production and embryo implantation. The uPA inhibitor amiloride abrogated this increase.

Good or bad: Paradox of plasminogen activator inhibitor 1 (PAI-1) in digestive system tumors

The fibrinolytic system is involved in many physiological functions, among which the important members can interact with each other, either synergistically or antagonistically to participate in the pathogenesis of many diseases. Plasminogen activator inhibitor 1 (PAI-1) acts as a crucial element of the fibrinolytic system and functions in an anti-fibrinolytic manner in the normal coagulation process. It inhibits plasminogen activator, and affects the relationship between cells and extracellular matrix. PAI-1 not only involved in blood diseases, inflammation, obesity and metabolic syndrome but also in tumor pathology. Especially PAI-1 plays a different role in different digestive tumors as an oncogene or cancer suppressor, even a dual role for the same cancer. We term this phenomenon "PAI-1 paradox". PAI-1 is acknowledged to have both uPA-dependent and -independent effects, and its different actions can result in both beneficial and adverse consequences. Therefore, this review will elaborate on PAI-1 structure, the dual value of PAI-1 in different digestive system tumors, gene polymorphisms, the uPA-dependent and -independent mechanisms of regulatory networks, and the drugs targeted by PAI-1 to deepen the comprehensive understanding of PAI-1 in digestive system tumors.

The Perspective of Vitamin D on suPAR-Related AKI in COVID-19

The coronavirus disease 2019 (COVID-19) pandemic has claimed the lives of millions of people around the world. Severe vitamin D deficiency can increase the risk of death in people with COVID-19. There is growing evidence that acute kidney injury (AKI) is common in COVID-19 patients and is associated with poorer clinical outcomes. The kidney effects of SARS-CoV-2 are directly mediated by angiotensin 2-converting enzyme (ACE2) receptors. AKI is also caused by indirect causes such as the hypercoagulable state and microvascular thrombosis. The increased release of soluble urokinase-type plasminogen activator receptor (suPAR) from immature myeloid cells reduces plasminogen activation by the competitive inhibition of urokinase-type plasminogen activator, which results in low plasmin levels and a fibrinolytic state in COVID-19. Frequent hypercoagulability in critically ill patients with COVID-19 may exacerbate the severity of thrombosis. Versican expression in proximal tubular cells leads to the proliferation of interstitial fibroblasts through the C3a and suPAR pathways. Vitamin D attenuates the local expression of podocyte uPAR and decreases elevated circulating suPAR levels caused by systemic inflammation. This decrease preserves the function and structure of the glomerular barrier, thereby maintaining renal function. The attenuated hyperinflammatory state reduces complement activation, resulting in lower serum C3a levels. Vitamin D can also protect against COVID-19 by modulating innate and adaptive immunity, increasing ACE2 expression, and inhibiting the renin–angiotensin–aldosterone system. We hypothesized that by reducing suPAR levels, appropriate vitamin D supplementation could prevent the progression and reduce the severity of AKI in COVID-19 patients, although the data available require further elucidation.

HGF and MET: From Brain Development to Neurological Disorders

Hepatocyte growth factor (HGF) and its tyrosine kinase receptor, encoded by the MET cellular proto-oncogene, are expressed in the nervous system from pre-natal development to adult life, where they are involved in neuronal growth and survival. In this review, we highlight, beyond the neurotrophic action, novel roles of HGF-MET in synaptogenesis during post-natal brain development and the connection between deregulation of MET expression and developmental disorders such as autism spectrum disorder (ASD). On the pharmacology side, HGF-induced MET activation exerts beneficial neuroprotective effects also in adulthood, specifically in neurodegenerative disease, and in preclinical models of cerebral ischemia, spinal cord injuries, and neurological pathologies, such as Alzheimer’s disease (AD), amyotrophic lateral sclerosis (ALS), and multiple sclerosis (MS). HGF is a key factor preventing neuronal death and promoting survival through pro-angiogenic, anti-inflammatory, and immune-modulatory mechanisms. Recent evidence suggests that HGF acts on neural stem cells to enhance neuroregeneration. The possible therapeutic application of HGF and HGF mimetics for the treatment of neurological disorders is discussed.

Fibrinolytic System and Cancer: Diagnostic and Therapeutic Applications

Fibrinolysis is a crucial physiological process that helps to maintain a hemostatic balance by counteracting excessive thrombosis. The components of the fibrinolytic system are well established and are associated with a wide array of physiological and pathophysiological processes. The aberrant expression of several components, especially urokinase-type plasminogen activator (uPA), its cognate receptor uPAR, and plasminogen activator inhibitor-1 (PAI-1), has shown a direct correlation with increased tumor growth, invasiveness, and metastasis. As a result, targeting the fibrinolytic system has been of great interest in the field of cancer biology. Even though there is a plethora of encouraging preclinical evidence on the potential therapeutic benefits of targeting the key oncogenic components of the fibrinolytic system, none of them made it from “bench to bedside” due to a limited number of clinical trials on them. This review summarizes our existing understanding of the various diagnostic and therapeutic strategies targeting the fibrinolytic system during cancer.

Dissection of the Ovulatory Process Using ex vivo Approaches

Ovulation is a unique physiological phenomenon that is essential for sexual reproduction. It refers to the entire process of ovarian follicle responses to hormonal stimulation resulting in the release of mature fertilization-competent oocytes from the follicles and ovaries. Remarkably, ovulation in different species can be reproduced out-of-body with high fidelity. Moreover, most of the molecular mechanisms and signaling pathways engaged in this process have been delineated using in vitro ovulation models. Here, we provide an overview of the major molecular and cytological events of ovulation observed in frogs, primarily in the African clawed frog Xenopus laevis, using mainly ex vivo approaches, with the focus on meiotic oocyte maturation and follicle rupture. For the purpose of comparison and generalization, we also refer extensively to ovulation in other biological species, most notoriously, in mammals.

Thrombospondin-1 as a Potential Therapeutic Target: Multiple Roles in Cancers

Thrombospondin-1, an extracellular matrix protein, is the first identified natural angiogenesis inhibitor. Thrombospondin-1 participates in a great number of physiological and pathological processes, including cell-cell and cell-matrix interactions via a number of cell receptors, including CD36 and CD47, which plays a vital role in mediating inflammation and performs a promoting effect in pulmonary arterial vasculopathy and diabetes. Thrombospondin-1 consists of six domains, which combine with different molecules and participate in various functions in cancers, serving as a critical member in diverse pathways in cancers. Thrombospondin-1 works as a cancer promotor in some pathways but as a cancer suppressor in others, which makes it highly possible that its erroneous functioning might lead to opposite effects. Therefore, subdividing the roles of thrombospondin-1 and distinguishing them in cancers are necessary. Complex structure and multiple roles take disadvantage of the research and application of thrombospondin-1. Compared with the whole thrombospondin-1 protein, each thrombospondin- 1 active peptide performs an uncomplicated structure and, nevertheless, a specific role. In other words, various thrombospondin-1 active peptides may function differently. For instance, thrombospondin-1 could both promote and inhibit glioblastoma, which is significantly inhibited by the three type I repeats, a thrombospondin-1 active peptide but promoted by the fragment 167-569, a thrombospondin-1 active peptide consisting of the procollagen homology domain and the three type I repeats. Further studies of the functions of thrombospondin-1 active peptides and applying them reasonably are necessary. In addition to mediating cancerogenesis, thrombospondin-1 is also affected by cancer development, as reflected by its expression in plasma and the cancer tissue. Therefore, thrombospondin-1 may be a potential biomarker for pre-clinical and clinical application. This review summarizes findings on the multiple roles of thrombospondin-1 in cancer processes, with a focus on its use as a potential therapeutic target.

The urokinase-type plasminogen activator and inhibitors in resectable lung adenocarcinoma

BACKGROUND

The urokinase-type plasminogen activator (uPA) system is closely related to the occurrence and progression of cancer in many aspects. Previous studies demonstrated that the conclusions about the prognosis value of uPA, plasminogen activator inhibitor 1 (PAI-1) and plasminogen activator inhibitor 2 (PAI-2) in lung cancer are controversial, so this study was performed for the exploration of the predictive effect of uPA, PAI-1 and PAI-2 on the overall survival (OS) of resectable pulmonary adenocarcinoma patients.

METHODS

UPA, PAI-1 and PAI-2 expression levels were assayed by immunohistochemical staining based on tissue microarray (TMA) that is composed of formalin-fixed paraffin-embedded specimens from 84 resectable lung adenocarcinoma patients from July 2004 to June 2009. The relationship of IHC, mRNA expression levels of three molecules were investigated respectively. The three molecules' relationship with clinicopathologic parameters and OS was explored by Chi-square, Kaplan-Meier, and Cox regression analyses. The Cancer Genome Atlas (TCGA) database was used to analyze differential gene expressions of RNA-sequencing data of pulmonary adenocarcinoma and normal tissues, and Kaplan-Meier methods were adopted to confirm the prognostic value of uPA, PAI-1 and PAI-2 in resectable lung adenocarcinoma in TCGA database and the R package MethylMix was used to conduct an analysis integrating methylation data and gene expression of RNA-sequencing data based on TCGA.

RESULTS

UPA, PAI-1 and PAI-2 had much higher IHC expression levels in tumor than those in the normal tissues (uPA, Z = -10.511; PAI-1, Z = -4.836; PAI-2, Z = -6.794; all P < 0.0001). High DNA methylation level of gene uPA resulted in the decrease of its expression. In addition, expression level of PAI-2 was positively associated with tumor size (χ² = 8.372, P =  0.004). Multivariate analyses showed TNM stage III was an independent adverse prognostic factor (hazard ratio = 3.736, 95 % confidence interval = 1.097-12.72, P =  0.035). Kaplan-Meier method revealed that uPA, PAI-1 and PAI-2 expression levels were not related to the OS for 84 resectable lung adenocarcinoma patients. According to TCGA data, PAI-1 expression level was identified as a potential adverse predictor for prognosis of resectable lung adenocarcinoma (Gehan-Breslow-Wilcoxon test, P = 0.025).

CONCLUSIONS

Our data show that, the expression levels of uPA, PAI-1 and PAI-2 are significantly up-regulated in resectable lung adenocarcinoma. Besides, this study highlights PAI-1 as a latent adverse prognostic factor in resectable adenocarcinoma of lung.

Effects of transforming growth factor-β1 on plasminogen activation in stem cells from the apical papilla: role of activating receptor-like kinase 5/Smad2 and mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) signalling

AIM

To study the effects of TGF-β1 on the plasminogen activation (PA) system of stem cells from the apical papilla (SCAP) and its signalling.

METHODOLOGY

SCAP cells were isolated from the apical papilla of immature permanent teeth extracted for orthodontic reasons. They were exposed to various concentration of TGF-β1 with/without pretreatment and coincubation by SB431542 (ALK/Smad2/3 inhibitor), or U0126 (MEK/ERK inhibitor). MTT assay, Western blotting and enzyme-linked immunosorbent assay (ELISA) were used to detect their effects on cell viability, and the protein expression of plasminogen activator inhibitor-1 (PAI-1), urokinase-type plasminogen activator (uPA), uPA receptor (uPAR) and their secretion. The paired Student's t-test was used for statistical analysis.

RESULTS

TGF-β1 significantly stimulated PAI-1 and soluble uPAR (suPAR) secretion of SCAP cells (P < 0.05), whereas uPA secretion was inhibited. Accordingly, TGF-β1 induced both PAI-1 and uPAR protein expression of SCAP cells. SB431542 (an ALK5/Smad2/3 inhibitor) pretreatment and coincubation prevented the TGF-β1-induced PAI-1 and uPAR of SCAP. U0126 attenuated the TGF-β1-induced expression/secretion of uPAR, but not PAI-1 in SCAP. SB431542 reversed the TGF-β1-induced decline of uPA.

CONCLUSIONS

TGF-β1 may affect the repair/regeneration activities of SCAP via differential increase or decrease of PAI-1, uPA and uPAR. These effects induced by TGF-β1 are associated with ALK5/Smad2/3 and MEK/ERK activation. Elucidation the signalling pathways and effects of TGF-β1 is useful for treatment of immature teeth with open apex by revascularization/revitalization procedures and tissue repair/regeneration.

Ovulation: Parallels With Inflammatory Processes

The midcycle surge of LH sets in motion interconnected networks of signaling cascades to bring about rupture of the follicle and release of the oocyte during ovulation. Many mediators of these LH-induced signaling cascades are associated with inflammation, leading to the postulate that ovulation is similar to an inflammatory response. First responders to the LH surge are granulosa and theca cells, which produce steroids, prostaglandins, chemokines, and cytokines, which are also mediators of inflammatory processes. These mediators, in turn, activate both nonimmune ovarian cells as well as resident immune cells within the ovary; additional immune cells are also attracted to the ovary. Collectively, these cells regulate proteolytic pathways to reorganize the follicular stroma, disrupt the granulosa cell basal lamina, and facilitate invasion of vascular endothelial cells. LH-induced mediators initiate cumulus expansion and cumulus oocyte complex detachment, whereas the follicular apex undergoes extensive extracellular matrix remodeling and a loss of the surface epithelium. The remainder of the follicle undergoes rapid angiogenesis and functional differentiation of granulosa and theca cells. Ultimately, these functional and structural changes culminate in follicular rupture and oocyte release. Throughout the ovulatory process, the importance of inflammatory responses is highlighted by the commonalities and similarities between many of these events associated with ovulation and inflammation. However, ovulation includes processes that are distinct from inflammation, such as regulation of steroid action, oocyte maturation, and the eventual release of the oocyte. This review focuses on the commonalities between inflammatory responses and the process of ovulation.

uPA affects the CRSsNP nasal mucosa epithelium apoptosis by regulating WIF1

Chronic rhinosinusitis without nasal polyps (CRSsNP) is the main type of Chronic rhinosinusitis (CRS) and is a common otorhinolaryngologic disease worldwide. However, the mechanisms of CRSsNP remain poorly understood. In this study, C57BL/6J wild-type and urokinase-type plasminogen activator (uPA) gene knockout (uPA^-/-) mice were used to construct the CRSsNP model. Primary human nasal epithelial cells (HNEC) were isolated from CRSsNP patient and treated with uPA knockdown/overexpression lentivirus. CCK-8 and Annexin-V/PI staining were used to detected cell proliferation and apoptosis. In vivo, we found that uPA depletion alleviated mucosal inflammation in the CRSsNP mice model. Wnt inhibitory factor 1 (WIF1) was upregulated in the uPA^-/- CRSsNP mice model. In vitro, inhibition of uPA increased cell proliferation and decreased cell apoptosis. Mechanistically, uPA depletion upregulated WIF1 and BCL2 expression, and reduced the expression level of BAX in CRSsNP HNEC. In contrast, decreased cell proliferation and increased cell apoptosis were observed after uPA overexpression. Consistently, a reduction in WIF1 and BCL2 expression levels and an increase in the BAX expression level were observed upon uPA ectopic expression. Furthermore, WIF1 overexpression rescued the effects caused by uPA overexpression in vitro. In conclusion, uPA affects the CRSsNP nasal mucosal epithelium cell apoptosis by upregulating WIF1. To our knowledge, this is the first study to explore the role of uPA in CRSsNP to date.

Inherited genetic predispositions in F13A1 and F13B genes predict abdominal adhesion formation: identification of gender prognostic indicators

Abdominal adhesions (AA) account for the most common complication of peritoneal surgery with bowel obstruction being the severest problem in the absence of effective predicting biomarkers. Anti-AA-barriers or adhesiolysis did not completely prevent bowel obstruction, although there is evidence they might reduce related complications requiring reoperation. In addition, gender-related predispositions have not been adequately investigated. We explored the role of coagulation Factor XIII (F13A1 and F13B subunit-genes) in patients following laparotomy, mostly median/lower median incision line. Globally, 426 patients (54%,♀), were PCR-SNP-genotyped for FXIIIA V34L (rs5985), FXIIIA P564L (rs5982), FXIIIA Y204F (rs3024477) and FXIIIB H95R (rs6003). Patients' clinical phenotypes were: Group-A (n = 212), those who developed AA, and 55.2% of them developed bowel obstruction (subgroup-A1), the remaining were subgroup-A2; Group B (n = 214) were those who did not develop AA (subgroup-B1; 53.3%) or symptoms/complications (subgroup-B2). Among different laparotomy, colon surgery associated with AA at a major extent (OR = 5.1; 3.24-7.8; P < 0.0001) with different gender scores (♀OR = 5.33; 2.32-12.23; P < 0.0001 and ♂OR = 3.44; 1.58-7.49; P < 0.0001). Among SNPs, P564L (OR = 4.42; 1.45-13.4; P = 0.008) and Y204F (OR = 7.78; 1.62-37.3; P = 0.01) significantly predicted bowel obstruction and survival-analyses yielded interesting gender distinctions (♀HR = 5.28; 2.36-11.8; P = 0.00005; ♂HR = 2.22; 1.31-3.85; P = 0.0034). Active compounds preventing AA belong to the anticoagulant/fibrinolysis areas, suggesting them candidate investigation targets. We identified novel prognostic markers to predict AA/bowel obstruction giving insights to design novel therapeutic and gender prevention programs.

The role of Pdcd4 in tumour suppression and protein translation

Programmed cell death 4 (Pdcd4), a tumour suppressor, is frequently down-regulated in various types of cancer. Pdcd4 has been demonstrated to efficiently suppress tumour promotion, progression and proliferation. The biochemical function of Pdcd4 is a protein translation inhibitor. Although the fact that Pdcd4 inhibits protein translation has been known for more than a decade, the mechanism by which Pdcd4 controls tumorigenesis through translational regulation of its target genes is still not fully understood. Recent studies show that Pdcd4 inhibits translation of stress-activated-protein kinase interacting protein 1 to suppress tumour invasion, depicting a picture of how Pdcd4 inhibits tumorigenesis through translational inhibition. Thus, understanding the mechanism of how Pdcd4 attenuates tumorigenesis by translational control should provide a new strategy for combating cancer.

Multifaceted Role of the Urokinase-Type Plasminogen Activator (uPA) and Its Receptor (uPAR): Diagnostic, Prognostic, and Therapeutic Applications

The plasminogen activator (PA) system is an extracellular proteolytic enzyme system associated with various physiological and pathophysiological processes. A large body of evidence support that among the various components of the PA system, urokinase-type plasminogen activator (uPA), its receptor (uPAR), and plasminogen activator inhibitor-1 and -2 (PAI-1 and PAI-2) play a major role in tumor progression and metastasis. The binding of uPA with uPAR is instrumental for the activation of plasminogen to plasmin, which in turn initiates a series of proteolytic cascade to degrade the components of the extracellular matrix, and thereby, cause tumor cell migration from the primary site of origin to a distant secondary organ. The components of the PA system show altered expression patterns in several common malignancies, which have identified them as ideal diagnostic, prognostic, and therapeutic targets to reduce cancer-associated morbidity and mortality. This review summarizes the various components of the PA system and focuses on the role of uPA-uPAR in different biological processes especially in the context of malignancy. We also discuss the current state of knowledge of uPA-uPAR-targeted diagnostic and therapeutic strategies for various malignancies.

Potential microRNA-related Targets for Therapeutic Intervention with Ovarian Cancer Metastasis

Treatment of disseminated epithelial ovarian cancer (EOC) is an unmet medical need. Therefore, the identification along with preclinical and clinical validation of new targets is an issue of high importance. In this review we focus on microRNAs that mediate metastasis of EOC. We summarize up-regulated metastasis-promoting and down-regulated metastasis-suppressing microRNAs. We focus on preclinical in vitro and in vivo functions as well as their metastasis-related clinical correlations. Finally, we outline modalities for therapeutic intervention and critical issues of microRNA-based therapeutics in the context of metastatic EOC.

The urokinase-type plasminogen activator system and its role in tumor progression

In the multistage process of carcinogenesis, the key link in the growth and progression of the tumor is the invasion of malignant cells into normal tissue and their distribution and the degree of destruction of tissues. The most important role in the development of these processes is played by the system of urokinase-type plasminogen activator (uPA system), which consists of several components: serine proteinase – uPA, its receptor – uPAR and its two endogenous inhibitors – PAI-1 and PAI-2. The components of the uPA system are expressed by cancer cells to a greater extent than normal tissue cells. uPA converts plasminogen into broad spectrum, polyfunctional protease plasmin, which, in addition to the regulation of fibrinolysis, can hydrolyze a number of components of the connective tissue matrix (СTM), as well as activate the zymogens of secreted matrix metalloproteinases (MMР) – pro-MMР. MMРs together can hydrolyze all the main components of the СTM, and thus play a key role in the development of invasive processes, as well as to perform regulatory functions by activating and releasing from STM a number of biologically active molecules that are involved in the regulation of the main processes of carcinogenesis. The uPA system promotes tumor progression not only through the proteolytic cascade, but also through uPAR, PAI-1 and PAI-2, which are involved in both the regulation of uPA/uPAR activity and are involved in proliferation, apoptosis, chemotaxis, adhesion, migration and activation of epithelial-mesenchymal transition pathways. All of the above processes are aimed at regulating invasion, metastasis and angiogenesis. The components of the uPA system are used as prognostic and diagnostic markers of many cancers, as well as serve as targets for anticancer therapy.

Effects of TGF-β1 on plasminogen activation in human dental pulp cells: Role of ALK5/Smad2, TAK1 and MEK/ERK signalling

Transforming growth factor-β1 (TGF-β1) plays an important role in the pulpal repair and dentinogenesis. Plasminogen activation (PA) system regulates extracellular matrix turnover. In this study, we investigated the effects of TGF-β1 on PA system of dental pulp cells and its signalling pathways. Dental pulp cells were treated with different concentrations of TGF-β1. MTT assay, reverse transcription-polymerase chain reaction, Western blotting and enzyme-linked immunosorbant assay (ELISA) were used to detect the effect of TGF-β1 on cell viability, mRNA and protein expression of urokinase-type plasminogen activator (uPA), uPA receptor (uPAR), plasminogen activator inhibitor-1 (PAI-1) as well as their secretion. The phosphorylation of Smad2 and TAK1 was analysed by Pathscan ELISA or Western blotting. Cells were pretreated with SB431542 (ALK5/Smad2/3 inhibitor), 5z-7-oxozeaenol (TAK1 inhibitor) and U0126 (MEK/ERK inhibitor) for examining the related signalling. TGF-β1 slightly inhibited cell growth that was reversed by SB431542. TGF-β1 upregulated both RNA and protein expression of PAI-1 and uPAR, whereas it downregulated uPA expression. Accordingly, TGF-β1 stimulated PAI-1 and soluble uPAR (suPAR) secretion of pulp cells, whereas uPA secretion was inhibited. TGF-β1 induced the phosphorylation of Smad2 and TAK1. In addition, SB431542, 5z-7-oxozeaenol and U0126 attenuated the TGF-β1-induced secretion of PAI-1 and suPAR. These results indicate that TGF-β1 is possibly involved in the repair/regeneration and inflammatory processes of dental pulp via regulation of PAI-1, uPA and uPAR. These effects of TGF-β1 are related to activation of ALK5/Smad2, TAK1 and MEK/ERK signalling pathways. Clarifying the signal transduction for the effects of TGF-β1 is helpful for pulpo-dentin regeneration and tissue engineering. Copyright © 2016 John Wiley & Sons, Ltd.

Low-density lipoprotein receptor-related protein-1: role in the regulation of vascular integrity

Low-density lipoprotein receptor-related protein-1 (LRP1) is a large endocytic and signaling receptor that is widely expressed. In the liver, LRP1 plays an important role in regulating the plasma levels of blood coagulation factor VIII (fVIII) by mediating its uptake and subsequent degradation. fVIII is a key plasma protein that is deficient in hemophilia A and circulates in complex with von Willebrand factor. Because von Willebrand factor blocks binding of fVIII to LRP1, questions remain on the molecular mechanisms by which LRP1 removes fVIII from the circulation. LRP1 also regulates cell surface levels of tissue factor, a component of the extrinsic blood coagulation pathway. This occurs when tissue factor pathway inhibitor bridges the fVII/tissue factor complex to LRP1, resulting in rapid LRP1-mediated internalization and downregulation of coagulant activity. In the vasculature LRP1 also plays protective role from the development of aneurysms. Mice in which the lrp1 gene is selectively deleted in vascular smooth muscle cells develop a phenotype similar to the progression of aneurysm formation in human patient, revealing that these mice are ideal for investigating molecular mechanisms associated with aneurysm formation. Studies suggest that LRP1 protects against elastin fiber fragmentation by reducing excess protease activity in the vessel wall. These proteases include high-temperature requirement factor A1, matrix metalloproteinase 2, matrix metalloproteinase-9, and membrane associated type 1-matrix metalloproteinase. In addition, LRP1 regulates matrix deposition, in part, by modulating levels of connective tissue growth factor. Defining pathways modulated by LRP1 that lead to aneurysm formation and defining its role in thrombosis may allow for more effective intervention in patients.

Antiplasmin, but not amiloride, prevents synovitis and cartilage damage following hemarthrosis in hemophilic mice

BACKGROUND

Blood-induced joint damage is characterized by synovitis and cartilage damage. Recently, we demonstrated that joint bleeding in hemophilic mice results in elevated synovial levels of urokinase plasminogen activator (u-PA) and plasmin, and in plasmin-mediated cartilage damage.

OBJECTIVE

To evaluate whether treatment with amiloride (an inhibitor of u-PA) or antiplasmin attenuates synovitis and cartilage damage following joint bleeding in hemophilic mice.

METHODS

Following the induction of joint bleeding, hemophilic mice were randomized between daily oral treatment with amiloride (1 mg kg⁻¹) or control, or weekly intra-articular treatment with amiloride (2.5 mg mL⁻¹), antiplasmin (2.5 mg mL⁻¹), or control. After 5 weeks of treatment, synovitis and cartilage damage were determined on hematoxylin and eosin-stained (Valentino score) and Safranin O-stained sections, respectively.

RESULTS

No effects of oral and intra-articular treatment with amiloride were found. In contrast, intra-articular treatment with antiplasmin resulted in significant (P < 0.01) reductions in both synovitis (score 1, 11.1% vs. 0%; score 2, 11.1% vs. 4.2%; score 3, 61.1% vs. 16.7%; score 4, 5.6% vs. 29.2%; score 5, 11.1% vs. 20.8%; score 6, 7.7% vs. 8.3%; score 7, 0% vs. 8.3%; and score 8, 0% vs. 12.5%) and cartilage damage (score 2, 10% vs. 8.3%; score 3, 50% vs. 12.5%; score 4, 30% vs. 33.3%; score 5, 10% vs. 33.3%; and score 6, 0% vs. 16.7%) as compared with controls.

CONCLUSIONS

Intra-articular treatment with antiplasmin (but not amiloride) following joint bleeding prevented synovitis and cartilage damage in hemophilic mice. These data offer promise for the use of antiplasmin as a new therapeutic intervention for patients who suffer from joint bleeds despite administration of clotting factor.

Glomerular mRNA expression of prothrombotic and antithrombotic factors in renal transplants with thrombotic microangiopathy

BACKGROUND

Thrombotic microangiopathy (TMA) in renal transplants (rTx-TMA) is a serious complication and is usually either recurrent TMA (RecTMA) due to humoral rejection (HR-TMA) or due to calcineurin inhibitor toxicity (CNI-TMA). Although the triggers are known, our knowledge about the thrombogenic transcriptome changes in the microvessels is rudimentary.

METHODS

We examined the expression of several prothrombotic and antithrombotic genes in 25 biopsies with rTx-TMA (6 RecTMA, 9 HR-TMA, and 10 CNI-TMA) and 8 controls. RNA from microdissected glomeruli of paraffin-embedded tissue was isolated and mRNA transcripts were quantified with real-time polymerase chain reaction after preamplification. Results were correlated with clinicopathologic parameters.

RESULTS

Glomerular mRNA expression of KLF2, KLF4, and tPA was lower and that of PAI-1 was higher in rTx-TMA than in the controls. Glomerular mRNA expression of KLF2 and KLF4 correlated with that of tPA and inversely with that of PAI-1 in rTx-TMA. The mRNA expression of complement regulators CD46 and CD59 were higher in rTx-TMA than in the controls. Only in HR-TMA were glomerular ADAMTS13 and CD55 down-regulated.

CONCLUSIONS

The glomerular capillary bed seems to contribute to all subtypes of rTx-TMA by down-regulation of the endothelial transcription factors KLF2 and KLF4, indicating dedifferentiation with subsequent up-regulation of PAI-1 and down-regulation of tPA, resulting in inhibition of local fibrinolysis. Decreased glomerular expression of ADAMTS13 and CD55 could be an additional pathway toward microthrombosis exclusively in HR-TMA.

Plasma tissue-type plasminogen activator increases fibrinolytic activity of exogenous urokinase-type plasminogen activator

The relationship between tissue-type plasminogen activator (tPA) and urokinase-type plasminogen activator (uPA) function is not fully understood. The aim of this study was to compare in vitro the fibrinolytic activity of tPA and uPA and evaluate their possible interaction. Blood coagulation and fibrinolysis were conducted by rotation thromboelastometry, whereas blood clotting was induced by CaCl2 and tissue factor and fibrinolysis additively by tPA and uPA. Effective concentration 50% of tPA and uPA fibrinolytic activity in blood was found to be 90 and 33 IU/ml relating to the units of activity established by manufacturers in the absence of blood. uPA-induced fibrinolysis in blood was faster compared with tPA used at the same units of activity. In contrast, in a blood-free system containing fibrinogen, plasminogen, and thrombin, fibrinolysis induced by uPA was weaker than by tPA. Treating of blood with tranexamic acid (60 mmol/l) was followed by decreased fibrinolytic potential of both exogenous tPA and uPA, despite uPA by itself is known to be not sensitive to aminocaproic acids. Thus, uPA exerted stronger activity in blood but weaker activity in blood-free system, compared with tPA. Taking into account the intermolecular binding of uPA to tPA, it could be suggested that interaction of exogenous uPA with plasma-containing tPA provided amplification of fibrinolysis due to formation of uPA/tPA complex possessing high affinity to fibrin.

Serine-proteases as plasminogen activators in terms of fibrinolysis

OBJECTIVES

This review should give an overview about the natural human plasminogen activators and their various modified variants as well as similar substances isolated from animals, microorganisms and plants. When a blood clot is formed in a blood vessel, it avoids the oxygen supply of the surrounding tissue. A fast fibrinolytic therapy should redissolve the blood vessel and reduce the degradation of the tissue. All proteases that are part of the human blood coagulation and fibrinolytic system belong to the serine protease family. t-PA (tissue plasminogen activator) and u-PA (urokinase plasminogen activator) are the naturally occurring fibrinolytic agents that are also used in therapy.

KEY FINDINGS

Despite many years of research, t-PA is still the gold standard in fibrinolytic therapy. But it has to be given as an infusion, which needs time. Modified fibrinolytic substances are, were, or perhaps will be in the market. They have different advantages over t-PA, but often the disadvantages predominate.

CONCLUSION

Many substances have been developed but an optimal fibrinolytic agent combined with a simple administration is not in therapeutic use to date.

Natural and engineered plasmin inhibitors: applications and design strategies

The serine protease plasmin is ubiquitously expressed throughout the human body in the form of the zymogen plasminogen. Conversion to active plasmin occurs through enzymatic cleavage by plasminogen activators. The plasminogen activator/plasmin system has a well-established function in the removal of intravascular fibrin deposition through fibrinolysis and the inhibition of plasmin activity; this has found widespread clinical use in reducing perioperative bleeding. Increasing evidence also suggests diverse, although currently less defined, roles for plasmin in a number of physiological and pathological processes relating to extracellular matrix degradation, cell migration and tissue remodelling. In particular, dysregulation of plasmin has been linked to cancer invasion/metastasis and various chronic inflammatory conditions; this has prompted efforts to develop inhibitors of this protease. Although a number of plasmin inhibitors exist, they commonly suffer from poor potency and/or specificity of inhibition that either results in reduced efficacy or prevents clinical use. Consequently, there is a need for further development of high-affinity plasmin inhibitors that maintain selectivity over other serine proteases. This review summarises clearly defined and potential applications for plasmin inhibition. The properties of naturally occurring and engineered plasmin inhibitors are discussed in the context of current knowledge regarding plasmin structure, specificity and function. This includes design strategies to obtain the potency and specificity of inhibition in addition to controlled temporal and spatial distribution tailored for the intended use.

Soya protein hydrolysates modify the expression of various pro-inflammatory genes induced by fatty acids in ovine phagocytes

The objective of the present study was to test the hypothesis that fatty acids are the circulating mediators acting in a pro-inflammatory manner towards activated circulating ovine monocyte/macrophages and neutrophils. Furthermore, whether soya protein hydrolysates (SPH) inhibit the fatty acid-induced increase in the production of pro-inflammatory responses by ovine phagocytes was tested in vitro. All the fatty acids tested (myristic, palmitic, palmitoleic, stearic and oleic) increased (P < 0·01; C18>C16>C14) membrane-bound urokinase plasminogen activator (u-PA) and u-PA free binding sites in cell membranes of activated ovine blood monocytes/macrophages, but only the C18 fatty acids (stearic, oleic) were effective towards blood neutrophils. The C18 fatty acids up-regulated (P < 0·05) the gene expression of u-PA, u-PA receptor, intercellular adhesion molecule 1 and inducible NO synthase (in monocytes) but not that of cyclo-oxygenase-2, integrin α X and plasminogen activator inhibitor types 1 and 2 by ovine phagocytes. SPH blocked completely or partially all C18 fatty acid-induced changes in the expression of various pro-inflammatory genes. In conclusion, fatty acids selectively ‘activate’ ovine phagocytes, suggesting that these cells ‘sense’ metabolic signals derived from adipocytes. Soya protein peptides inhibit all changes in gene expression induced by fatty acids in ovine phagocytes in vitro. This constitutes a novel mechanism of action.

Pathogenesis of postoperative adhesion formation

Background

Current views on the pathogenesis of adhesion formation are based on the ‘classical concept of adhesion formation’, namely that a reduction in peritoneal fibrinolytic activity following peritoneal trauma is of key importance in adhesion development.

Methods

A non-systematic literature search (1960–2010) was performed in PubMed to identify all original articles on the pathogenesis of adhesion formation. Information was sought on the role of the fibrinolytic, coagulatory and inflammatory systems in the disease process.

Results

One unifying concept emerged when assessing 50 years of studies in animals and humans on the pathogenesis of adhesion formation. Peritoneal damage inflicted by surgical trauma or other insults evokes an inflammatory response, thereby promoting procoagulatory and antifibrinolytic reactions, and a subsequent significant increase in fibrin formation. Importantly, peritoneal inflammatory status seems a crucial factor in determining the duration and extent of the imbalance between fibrin formation and fibrin dissolution, and therefore in the persistence of fibrin deposits, determining whether or not adhesions develop.

Conclusion

Suppression of inflammation, manipulation of coagulation as well as direct augmentation of fibrinolytic activity may be promising antiadhesion treatment strategies.

Clinical significance of molecular detection of matrix metalloproteinase-1 in bone marrow and peripheral blood in patients with gastric cancer

PURPOSE

Matrix metalloproteinases are responsible for proteolytic degradation of basement membrane and extracellular matrix. In tumor tissues, elevated expression of matrix metalloproteinase-1 (MMP-1) has been associated with tumor invasion and metastasis. However, little is known about the expression of MMP-1 in peripheral blood (PB) and bone marrow (BM) in gastric cancer patients. Thus, the aim of the present study is to determine MMP-1 messenger RNA (mRNA) expression levels in BM and PB of patients with gastric cancer.

METHODS

The study group consisted of 857 patients with gastric cancer (577 males and 280 females) ranging in age from 27 to 87 years (average 61.6 years). MMP-1 mRNA expression levels in BM and PB were evaluated quantitatively by real-time reverse-transcription polymerase chain reaction (RT-PCR).

RESULTS

Expression of MMP-1 mRNA in BM and PB of patients with gastric cancer was significantly higher than in noncancer patients. High levels of MMP-1 mRNA expression were significantly associated with differentiated histology, tumor size, tumor invasiveness, lymph node metastasis, liver metastasis, and clinical stage. Particularly importantly, MMP-1 mRNA expression in PB was an independent factor of distant metastasis.

CONCLUSIONS

We disclosed that MMP-1 mRNA expression in peripheral blood and bone marrow of gastric cancer patients was very high, precisely reflecting staging of gastric cancer. MMP-1 mRNA expression in peripheral blood may be a useful marker for distant metastasis in gastric cancer.

Liver regeneration and the atrophy-hypertrophy complex

The atrophy-hypertrophy complex (AHC) refers to the controlled restoration of liver parenchyma following hepatocyte loss. Different types of injury (e.g., toxins, ischemia/reperfusion, biliary obstruction, and resection) elicit the same hypertrophic response in the remnant liver. The AHC involves complex anatomical, histological, cellular, and molecular processes. The signals responsible for these processes are both intrinsic and extrinsic to the liver and involve both physical and molecular events. In patients in whom resection of large liver malignancies would result in an inadequate functional liver remnant, preoperative portal vein embolization may increase the remnant liver sufficiently to permit aggressive resections. Through continued basic science research, the cellular mechanisms of the AHC may be maximized to permit curative resections in patients with potentially prohibitive liver function.

MicroRNAs in colorectal cancer metastasis

Metastatic disease is the major cause of death in colorectal cancer (CRC) patients. The metastatic process is highly inefficient and comprises multiple sequential steps. While many genetic factors relevant in this process have already been identified, the epigenetic factors underlying each step still remain obscure. MicroRNAs (miRNAs) are key regulators in tumourigenesis, but their role in the development of cancer metastasis is poorly investigated. The majority of miRNAs involved in the metastatic process have been identified in breast cancer cell lines, and in CRC less data are available. We review the role of miRNAs in the metastatic pathway of CRC, including escape of apoptosis, epithelial-mesenchymal transition (EMT), angiogenesis, and invasion. Better understanding of the complex role of miRNAs in the development of CRC metastases may provide new insights that could be of therapeutic consequence.

Urokinase plasminogen activator receptor in adipose tissue macrophages of morbidly obese subjects

OBJECTIVE

At present, circulating markers characterizing the inflammatory infiltration of white adipose tissue (WAT) in human obesity are not well known. We previously identified, by a pangenomic approach (microarrays), the urokinase plasminogen activator receptor (PLAUR or CD87) as a potential marker of subcutaneous adipose tissue macrophage infiltration (ATM).

METHOD

We studied i) the presence of PLAUR protein in WAT; ii) the PLAUR amount in plasma of obese patients; iii) the circulating variations during surgery-induced weight loss, and iv) the correlations between PLAUR circulating levels and bioclinical parameters.

RESULTS

We observed that PLAUR is preferentially expressed by infiltrating ATMs, with a typical localization on macrophage membrane. Circulating soluble PLAUR levels were significantly elevated in obese patients compared to lean controls. However, despite a trend towards a decrease 3 months after weight loss, PLAUR plasma levels were not modulated during a 1-year weight loss follow-up, suggesting the contribution of secretion sites other than subcutaneous WAT in obese patients.

CONCLUSIONS

These findings indicate that PLAUR mRNA expression could be used for the estimation of local subcutaneous ATMs infiltration in obese patients, but it cannot be used as a systemic marker of this inflammatory infiltration in dynamic phases of weight loss.

The autism risk genes MET and PLAUR differentially impact cortical development

Candidate risk genes for autism spectrum disorder (ASD) have been identified, but the challenge of determining their contribution to pathogenesis remains. We previously identified two ASD risk genes encoding the receptor tyrosine kinase MET and the urokinase plasminogen activator receptor (PLAUR), which is thought to modulate availability of the MET ligand. We also reported a role for Met signaling in cortical interneuron development in vitro and a reduction of these neurons in uPAR (mouse ortholog of PLAUR) null mice, suggesting that disruption of either gene impacts cortical development similarly. Here, we modify this conclusion, reporting that interneuron numbers are unchanged in the neocortex of Met(fx/fx) / Dlx5/6(cre) mice, in which Met is ablated from cells arising from the ventral telencephalon (VTel). Consistent with this, Met transcript is not detected in the VTel during interneuron genesis and migration; furthermore, during the postnatal period of interneuron maturation, Met is co-expressed in glutamatergic projection neurons, but not interneurons. Low levels of Met protein are expressed in the VTel at E12.5 and E14.5, likely reflecting the arrival of Met containing corticofugal axons. Met expression, however, is induced in E12.5 VTel cells after 2 days in vitro, perhaps underlying discrepancies between observations in vitro and in Met(fx/fx) / Dlx5/6(cre) mice. We suggest that, in vivo, Met impacts the development of cortical projection neurons, whereas uPAR influences interneuron maturation. An altered balance between excitation and inhibition has been postulated as a biological mechanism for ASD; this imbalance could arise from different risk genes differentially affecting either or both elements.

Acute mastitis induces upregulation of expression of plasminogen activator-related genes by blood monocytes and neutrophils in dairy ewes

The main objective of the present study was to examine whether genes implicated in the plasminogen activating cascade: urokinase-type plasminogen activator (u-PA), u-PA receptor (u-PAR) and plasminogen activator inhibitors type 1 (PAI-1) and type 2 (PAI-2) are expressed in a differential manner in ovine blood monocytes and neutrophils obtained from healthy and mastitic dairy ewes. A total of 48 blood samples were collected from 8 healthy and 8 mastitic dairy ewes over a period of 3 weeks. Streptococcus agalactiae was detected in milk samples isolated from mastitic animals. Results indicated that expression of all four genes was very low in monocytes and neutrophils isolated from healthy animals. In contrast, there was a 2- to 5-fold increase (P<0.05) in expression of all four genes in monocytes and an 18- to 38-fold increase (P<0.01) in neutrophils isolated from mastitic animals. In conclusion, upregulation of expression of u-PA and u-PAR by monocytes and neutrophils is probably related to the rapidity of migration of these cells towards the mammary gland, while the upregulation of PAI-1 and PAI-2 is a rather enigmatic observation and it is probably related to the successful localization of the infection.

Small-molecule modulators of zymogen activation in the fibrinolytic and coagulation systems

The coagulation and fibrinolytic systems are central to the hemostatic mechanism, which works promptly on vascular injury and tissue damage. The rapid response is generated by specific molecular interactions between components in these systems. Thus, the regulation mechanism of the systems is programmed in each component, as exemplified by the elegant processes in zymogen activation. This review describes recently identified small molecules that modulate the activation of zymogens in the fibrinolytic and coagulation systems.

Pdcd4, a colon cancer prognostic that is regulated by a microRNA

The novel tumor suppressor Pdcd4 inhibits neoplastic transformation, tumor progression and translation. Furthermore, we and others have recently shown that Pdcd4 suppresses invasion and intravasation, at least in part by suppressing expression of the invasion-related urokinase receptor (u-PAR) gene via the transcription factors Sp1/Sp3. Nevertheless, relatively little is known about mechanisms that regulate Pdcd4 expression in cancer. MicroRNAs (miRNAs) have been recently discovered and shown to be naturally occurring non-coding RNAs that control gene expression via specific sites within the 3'UTR of target miRNAs. This short review will focus on our recent finding that the microRNA miR-21 posttranscriptionally regulates Pdcd4, as well as invasion, intravasation, and metastasis. Furthermore, we will review the first translational and clinical results concerning the prognostic value of Pdcd4, in particular our own data that show Pdcd4 to be a novel and independent prognostic factor in colorectal cancer, and a potential supportive diagnostic tool for discriminating normal colonic tissues from benign adenomas and colorectal carcinomas.

Urokinase receptor, MMP-1 and MMP-9 are markers to differentiate prognosis, adenoma and carcinoma in thyroid malignancies

The identification of high-risk patients with thyroid cancer and the preoperative differentiation between follicular adenoma and carcinoma remain clinically challenging. Our study was conducted to analyze whether the quantification of matrix metalloproteinases (MMPs) and urokinase-type plasminogen activator receptor (u-PAR) and transcription factor binding to the u-PAR promoter improve prognostic predictability and differential diagnosis of thyroid tumors. Tumor/normal tissue was collected from 69 prospectively followed patients with thyroid carcinomas (papillary, medullary, follicular and anaplastic, PTC, MTC, FTC and ATC) or follicular adenomas. U-PAR, MMP-1, MMP-7 and MMP-9 amounts were determined by ELISA, and transcription factor binding was determined by electrophoretic mobility shift assay. Binding of transcription factors to the u-PAR promoter was observed, but not associated with u-PAR expression. Carcinomas except MTC expressed significantly more u-PAR/MMPs than adenomas/normal tissues, this being associated with advanced pT- or M-stages. MMP-1 and MMP-9 were significantly higher in follicular carcinomas than in adenomas. In carcinomas, high u-PAR-gene expression correlated significantly with high MMP-9, the latter being associated with MMP-7 in normal tissues. Poor survival in differentiated tumors was associated in trend (p = 0.07); poor survival of all patients (p = 0.043) and especially of patients with carcinomas of follicular origin (including ATC), but not medullary carcinomas, were significantly associated with high u-PAR-protein (p = 0.015). Quantification of u-PAR is of prognostic relevance in thyroid carcinomas of non-c-cell origin, and u-PAR in part may be regulated nontranscriptionally in thyroid cancers. This is the first study to suggest MMP-1/-9 as significant differentiation markers between follicular adenoma and follicular carcinoma.

Role of Urokinase Inhibitors in Choroidal Neovascularization

Cell migration is a critical step in the angiogenesis cascade that involves proteolysis of the basement membrane and extracellular matrix around existing blood vessels. The urokinase plasminogen activator (uPA) system has been involved in cellular invasion, angiogenesis and tumor growth. Similar expression of urokinase and its receptor (uPAR) is seen in both retinal and choroidal neovascularization. Significant inhibition of choroidal neovascularization (CNV) has been observed when cell surface associated uPA-uPAR activity is prevented with a specific inhibitor of this proteinase system. As the current treatments of CNV are not optimal, the urokinase-uPAR system appears to be an attractive target for alternative pharamacological therapy for CNV.

The urokinase plasminogen activator receptor promotes efferocytosis of apoptotic cells

The urokinase receptor (uPAR), expressed on the surface of many cell types, coordinates plasmin-mediated cell surface proteolysis for matrix remodeling and promotes cell adhesion by acting as a binding protein for vitronectin. There is great clinical interest in uPAR in the cancer field as numerous reports have demonstrated that up-regulation of the uPA system is correlated with malignancy of various carcinomas. Using both stable cell lines overexpressing uPAR and transient gene transfer, here we provide evidence for a non-reported role of uPAR in the phagocytosis of apoptotic cells, a process that has recently been termed efferocytosis. When uPAR was expressed in human embryonic kidney cells, hamster melanoma cells, or breast cancer cells (BCCs), there was a robust enhancement in the efferocytosis of apoptotic cells. uPAR-expressing cells failed to stimulate engulfment of viable cells, suggesting that uPAR enhances recognition of one or more determinant on the surface of the apoptotic cell. uPAR-mediated engulfment was not inhibited by expression of mutant beta5 integrin, nor was alphavbeta5 integrin-mediated engulfment modulated by cleavage of uPAR by phosphatidylinositol-specific phospholipase C. Further, we found that the more aggressive BCCs had a higher phagocytic capacity that correlated with uPAR expression and cleavage of membrane-associated uPAR in MDA-MB231 BCCs significantly impaired phagocytic activity. Because efferocytosis is critical for the resolution of inflammation and production of anti-inflammatory cytokines, overexpression of uPAR in tumor cells may promote a tolerogenic microenvironment that favors tumor progression.

Inhibitory effect of anti-hepatitis drug bicyclol on invasion of human hepatocellular carcinoma MHCC97-H cells with high metastasis potential and its relative mechanisms

To assess the anti-invasion effect of bicyclol (1) and its mechanism in human hepatocellular carcinoma (HCC) MHCC97-H cells with high metastatic potential. MTT assay was performed to evaluate the cytotoxicity of 1 to MHCC97-H cells and its inhibitory effect on the adhesion of these cells to laminin (LN) and fibronectin (FN). The anti-invasion effect of 1 was detected in an experiment using a transwell chamber. Transcription of vascular endothelial growth factor (VEGF), nm23-H1, and urokinase-type plasminogen activator receptor (uPAR) mRNAs was determined by an RT-PCR assay. The secretion and expression of alpha-fetoprotein (AFP) were analyzed by ELISA and flow cytometry, respectively. At concentrations of 10, 50, and 100 mumol/l, 1 obviously inhibited the adhesion of the MHCC97-H cells to LN and FN. The rates of inhibition of MHCC97-H cell invasion by 50 and 100 mumol/l for 1 were 37.3 and 50.2%, respectively. Drug 1 also decreased the expressions of VEGF, nm23-H1, and uPAR mRNA and the secretion of AFP in MHCC97-H cells. At low cytotoxic concentrations, the anti-hepatitis drug 1 demonstrated a significant anti-invasive effect in human HCC MHCC97-H cells with high metastatic potential. The inhibition of the expressions of VEGF, nm23-H1, and uPAR should contribute, at least in part, to the anti-invasion property of 1.

New insights into the molecular mechanisms of the fibrinolytic system

Fibrinolysis is regulated by specific molecular interactions between its main components. Activation of plasminogen by tissue-type plasminogen activator (t-PA) is enhanced in the presence of fibrin or at the endothelial cell surface. Urokinase-type plasminogen activator (u-PA) binds to a specific cellular u-PA receptor (u-PAR), resulting in enhanced activation of cell-bound plasminogen. Inhibition of fibrinolysis occurs at the level of plasminogen activation or at the level of plasmin. Assembly of fibrinolytic components at the surface of fibrin results in fibrin degradation. Assembly at the surface of cells provides a mechanism for generation of localized cell-associated proteolytic activity. This review includes novel proteins such a thrombin-activatable fibrinolysis inhibitor (TAFI) and discusses new insights into molecular mechanisms obtained from the rapidly growing knowledge of crystal structures of proteins.

The urokinase receptor (u-PAR)--a link between tumor cell dormancy and minimal residual disease in bone marrow?

Minimal residual disease (MRD) is hypothesized to be the major cause of tumor recurrence and metastasis even years and decades after primary cancer diagnosis and curative solid tumor resection. In these patients disseminated tumor cells reflecting MRD can be detected in the bone marrow years after treatment. It is to be assumed that genetic determinants and a complex interplay between the disseminated tumor cells and their microenvironment in the bone marrow are responsible for tumor cell dormancy and the final reactivation towards metastasis. The urokinase receptor (u-PAR), a critical regulator of invasion, intravasation, and metastasis, is found to be a key player in regulating the shift between single cell tumor dormancy and proliferation. This has mainly been attributed to a regulation by u-PAR of integrins, and the ability of the latter to propagate signals from fibronectin through the EGF-receptor, ERK, and p38 signaling. Interestingly, u-PAR is found in disseminated tumor cells in the bone marrow of solid cancer patients, and is associated with the expansion of these cells and clinical prognosis. Here we summarize and discuss findings on disseminated tumor cells in the bone marrow, MRD and the role of u-PAR in tumor biology, especially focusing on its specific role in providing a switch between tumor cell proliferation and dormancy. Finally, we discuss the hypothesis that u-PAR might be an essential molecule in bone marrow disseminated tumor cells for long-term survival during dormancy, and/or reactivation of their proliferation years after primary treatment.

Fatty acids differentially modify the expression of urokinase type plasminogen activator receptor in monocytes

The urokinase plasminogen activator system with its receptor uPAR contributes to the migratory potential of macrophages, a key event in atherosclerosis. We here investigated whether free fatty acids (FFA) modify the expression for uPAR in the PMA-differentiated human monocyte/macrophage-like cell line U937. Two hundred micromolar palmitate induced a threefold increase of the uPAR mRNA expression. Although the mono- and polyunsaturated fatty acids oleate and linoleate also stimulated uPAR expression, oleate had a significantly lower effect than palmitate. The observed effects were time and dose dependent. Inhibition of PKC-and ERK-pathways resulted in a strong down-regulation of basal uPAR expression whereas the FFA induced up-regulation remained unchanged. In contrast, FFA induced uPAR up-regulation was abolished by the specific inhibition of p38 MAPK. In conclusion we demonstrate that uPAR expression in human monocytes/macrophages is differentially stimulated by FFA. These effects are partially mediated by the p38 MAP-kinase signaling pathway.

LDL receptor-related protein 1: unique tissue-specific functions revealed by selective gene knockout studies

The LDL receptor-related protein (originally called LRP, but now referred to as LRP1) is a large endocytic receptor that is widely expressed in several tissues. LRP1 is a member of the LDL receptor family that plays diverse roles in various biological processes including lipoprotein metabolism, degradation of proteases, activation of lysosomal enzymes, and cellular entry of bacterial toxins and viruses. Deletion of the LRP1 gene leads to lethality in mice, revealing a critical, but as of yet, undefined role in development. Tissue-specific gene deletion studies reveal an important contribution of LRP1 in the vasculature, central nervous system, macrophages, and adipocytes. Three important properties of LRP1 dictate its diverse role in physiology: 1) its ability to recognize more than 30 distinct ligands, 2) its ability to bind a large number of cytoplasmic adaptor proteins via determinants located on its cytoplasmic domain in a phosphorylation-specific manner, and 3) its ability to associate with and modulate the activity of other transmembrane receptors such as integrins and receptor tyrosine kinases.

Disruption of cerebral cortex MET signaling in autism spectrum disorder

OBJECTIVE

Multiple genes contribute to autism spectrum disorder (ASD) susceptibility. One particularly promising candidate is the MET gene, which encodes a receptor tyrosine kinase that mediates hepatocyte growth factor (HGF) signaling in brain circuit formation, immune function, and gastrointestinal repair. The MET promoter variant rs1858830 allele "C" is strongly associated with ASD and results in reduced gene transcription. Here we examined expression levels of MET and members of the MET signaling pathway in postmortem cerebral cortex from ASD cases and healthy control subjects.

METHODS

Protein, total RNA, and DNA were extracted from postmortem temporal cortex gray matter samples (BA 41/42, 52, or 22) belonging to eight pairs of ASD cases and matched control subjects. MET protein expression was determined by Western blotting; messenger RNA expression of MET and other related transcripts was assayed by microarray and quantitative reverse transcriptase polymerase chain reaction.

RESULTS

MET protein levels were significantly decreased in ASD cases compared with control subjects. This was accompanied in ASD brains by increased messenger RNA expression for proteins involved in regulating MET signaling activity. Analyses of coexpression of MET and HGF demonstrated a positive correlation in control subjects that was disrupted in ASD cases.

INTERPRETATION

Altered expression of MET and related molecules suggests dysregulation of signaling that may contribute to altered circuit formation and function in ASD. The complement of genes that encode proteins involved in MET activation appears to undergo long-term compensatory changes in expression that may be a hallmark contribution to the pathophysiology of ASD.

Effect of ecdysone receptor gene switch ligands on endogenous gene expression in 293 cells

Regulated gene expression may substantially enhance gene therapy. Correlated with structural differences between insect ecdysteroids and mammalian steroids, the ecdysteroids appear to have a benign pharmacology without adversely interfering with mammalian signaling systems. Consequently, the ecdysone receptor-based gene switches are attractive for application in medicine. In the present study, the effect of inducers of ecdysone receptor switches on the expression of endogenous genes in HEK 293 cells was determined. Four ligand chemotypes, represented by a tetrahydroquinoline (RG-120499), one amidoketone (RG-121150), two ecdysteroids [20-hydroxyecdysone (20E) and ponasterone A (Pon A)], and four diacylhydrazines (RG-102240, RG-102277, RG-102398 and RG-100864), were tested in HEK 293 cells. The cells were exposed to ligands at concentrations of 1 microm (RG-120499) or 10 microm (all others) for 72 h and the total RNA was isolated and analyzed using microarrays. Microarray data showed that the tetrahydroquinoline ligand, RG-120499 caused cell death at concentrations > or = 10 microm. At 1 microm, this ligand caused changes in the expression of genes such as TNF, MAF, Rab and Reprimo. At 10 microm, the amidoketone, RG-121150, induced changes in the expression of genes such as v-jun, FBJ and EGR, but was otherwise noninterfering. Of the two steroids tested, 20E did not affect gene expression, but Pon A caused some changes in the expression of endogenous genes. At lower concentrations pharmacologically relevant for gene therapy, intrinsic gene expression effects of ecdysteroids and amidoketones may actually be insignificant. A fortiori, even at 10 microm, the four diacylhydrazine ligands did not cause significant changes in expression of endogenous genes in 293 cells and therefore should have minimum pleiotropic effects when used as ligands for the ecdysone receptor gene switch.

Analysis of specific transcriptional regulators as early predictors of independent prognostic relevance in resected colorectal cancer

PURPOSE

Prognostic studies on transcription factors acting at specific promoter elements have never been done so far. However, in tumors with long necessary follow-up, such as colorectal cancer, early-risk predictors would be needed. The invasion-related gene u-PAR is regulated via an activator protein 2 (AP-2)/Sp1 (-152/-135) and an AP-1 binding promoter motif (-190/-171), mediating u-PAR induction by K-Ras and Src. The present study was done to give first evidence for early prognostic relevance of transcription factors differentially bound to the u-PAR promoter, and their molecular inducers, in colorectal cancer.

EXPERIMENTAL DESIGN

Tumor/normal tissues of 92 prospectively followed (median = 26.3 months) patients were analyzed for Src activity/protein, K-ras mutations, and transcription factor binding to both u-PAR promoter motifs (in vivo gel shift, kinase assay, and PCR).

RESULTS

Kaplan-Meier/Mantel-Cox analysis showed a significant correlation among elevated Sp1/Sp3 binding to region -152/-135 (P = 0.002 and P = 0.006), the combinations of Sp1/AP-2 and Sp1/AP-1 binding to both motifs (P = 0.010 and P = 0.005), and Sp1 binding/high Src protein in tumors (P < 0.001), with poor survival. Survival decreased with the number of bound transcription factors to both motifs, with binding of three factors defining a high-risk group (P = 0.021). In multivariate analysis, elevated Sp1 binding, combinations of Sp1/AP-2 binding and Sp1/AP-1 binding, or Sp1 binding/high Src were independent prognostic variables; u-PAR expression itself being not yet prognostic. A first molecular staging model (CART) was defined, providing novel early high-risk groups (mean survival time as low as for non-curatively resected patients) from these variables.

CONCLUSIONS

This study defines transcription factors acting at specific promoter elements of an invasion-related gene, mediating specific signaling, as novel, independent, early predictors of prognosis in colorectal cancer.