Transcriptional control of cell density dependent regulation of matrix metalloproteinase and TIMP expression in breast cancer cell lines

Our recent studies on breast carcinoma cell lines with differing tumorigenicity / invasiveness (MCF-7< MDA-MB-468< MDAMB-231< MDA-MB-435) had shown significantly decreasing expression levels of MMPs-1,-2,-3,-8,-9,-10,-11 and –13 with increasing cell density while the levels of TIMP-1 and –2 increased. This correlated well with a lower invasiveness of confluent cells. In the present study, we extend our in vitro studies on three-dimensional cultures of breast cancer cell lines MCF-7 and MDAMB-435 and the transcriptional control of MMP and TIMP-expression in two-dimensional cultures of MDA-MB-231 and –435 cells. The tumor spheroid model showed that MMP expression and proteolytic activity were considerably higher in loosely structured tumor groups as compared to densely growing “compact” cell complexes. These data suggested that cell density regulates MMP and TIMP transcription and therefore, we tested whether AP-1, NFκB and CRE are involved in this process. Gene silencing of c-jun in sparse cultures had an inhibitory effect on MMP-3,–9 and –13 expression, on proteolytic activity as well as on the invasive potential of the cells, thus confirming a role for AP-1. TIMP-1, and –2 expression was up-regulated as compared to control cells. Consistent with this, overexpression of c-jun and c-fos in confluent breast cancer cell lines leads to up-regulation of MMP expression, proteolytic activity and invasion as well as down-regulation of TIMP-1. In summary, we provide evidence that cell density influences the invasive potential of tumor cells via regulation of MMPs and TIMPs by AP-1, NFκB and CRE transcription factors. Overexpression of MMPs in sparse cultures could help explain early dissemination of potentially metastatic cells.

Dissecting the impact of Frizzled receptors in Wnt/β-catenin signaling of human mesenchymal stem cells

Wnt/β-catenin signaling is of fundamental importance in the regulation of self-renewal, migration/invasion, and differentiation of human mesenchymal stem cells (hMSCs). Because little information is available about the function of Frizzled receptors (Fzds) as the main receptors of Wnt proteins in hMSCs, we first performed comparative Fzd mRNA expression profiling. Fzd9 and Fzd10 were not expressed in hMSCs. While Fzd3 was expressed at low levels in hMSCs, the other Fzds exhibited high expression rates. Activation and repression of Wnt signaling in hMSCs revealed that the expression levels of Fzd1, Fzd6, and Fzd7 are positively correlated with the Wnt/β-catenin activation status, whereas Fzd8 exhibited an inverse relation. For studying the functional relevance of Fzds in Wnt/β-catenin signaling, RNA interference, ectopic expression studies, and rescue approaches were performed in hMSCs carrying a highly sensitive TCF/LEF reporter gene system (Gaussia luciferase). We found that, Fzd1, Fzd5, Fzd7, and Fzd8 are largely involved in Wnt/β-catenin signaling of hMSCs. Moreover, the knockdown of Fzd5 can be compensated by the ectopic expression of Fzd7. Conversely, the ectopic expression of Fzd5 in Fzd7-knockdown hMSCs resulted in a rescue of Wnt/β-catenin signaling, pointing to a functional redundancy of Fzd5 and Fzd7.

Binding characteristics of [3H]-JSM10292: a new cell membrane-permeant non-peptide bradykinin B2 receptor antagonist

BACKGROUND AND PURPOSE

A (3) H-labelled derivative of the novel small-molecule bradykinin (BK) B(2) receptor antagonist JSM10292 was used to directly study its binding properties to human and animal B(2) receptors in intact cells and to closely define its binding site.

EXPERIMENTAL APPROACH

Equilibrium binding, dissociation and competition studies with various B(2) receptor ligands and [(3) H]-JSM10292 were performed at 4°C and 37°C. The experiments were carried out using HEK293 cells stably (over)expressing wild-type and mutant B(2) receptors of human and animal origin.

KEY RESULTS

[(3) H]-JSM10292 bound to B(2) receptors at 4°C and at 37°C with the same high affinity. Its dissociation strongly depended on the temperature and increased when unlabelled B(2) receptor agonists or antagonists were added. [(3) H]-JSM10292 is cell membrane-permeant and thus also bound to intracellular, active B(2) receptors, as indicated by the different 'nonspecific' binding in the presence of unlabelled JSM10292 or of membrane-impermeant BK. Equilibrium binding curves with [(3) H]-JSM10292 and competition experiments with unlabelled JSM10292 and [(3) H]-BK showed a different affinity profile for the wild-type B(2) receptor in different species (man, cynomolgus, rabbit, mouse, rat, dog, pig, guinea pig). Characterization of B(2) receptor mutants and species orthologues combined with homology modelling, using the CXCR4 as template, suggests that the binding site of JSM10292 is different from that of BK but overlaps with that of MEN16132, another small non-peptide B(2) receptor ligand.

CONCLUSIONS AND IMPLICATIONS

[(3) H]-JSM10292 is a novel, cell membrane-permeant, high-affinity B(2) receptor antagonist that allows direct in detail studies of active, surface and intracellularly located wild-type and mutant B(2) receptors.

Reporter gene HEK 293 cells and WNT/Frizzled fusion proteins as tools to study WNT signaling pathways

WNT/Frizzled receptor (FZD) signaling pathways are pivotal for physiological and pathophysiological processes. In humans, the complexity of WNT/FZD signaling is based on 19 WNTs, 10 FZDs and at least two (co)receptors (LRP5/6) mediating supposably four different signaling cascades. The detailed investigation of the specific function of the different initiating components is primarily hampered by the lack of most WNT proteins in a purified form. Therefore, we constructed and examined a chimeric protein of WNT3a and FZD4 as a suitable approach to overcome this obstacle for future studies of the specificity of other WNT/FZD combinations. Furthermore, we produced four different reporter HEK 293 cell lines to quantify the induced activation of the proposed signaling cascades, the β-catenin-, the NFAT-, the AP-1- and the CRE-regulated pathways. The chimera WNT3aFZD4 efficiently induced β-catenin-mediated luciferase activity. This activity was increased 40-fold compared with basal when LRP6 was stably cotransfected, proving that the chimera WNT3aFZD4 can also interact efficiently with LRP6. Our results demonstrate that the approach of using reporter gene cell lines in combination with WNT/FZD chimeras is efficient to study the β-catenin-mediated pathway and should also allow clarifying the specificity of WNT/FZD combinations in the activation of the other pathways.

The effects of a plant proteinase inhibitor from Enterolobium contortisiliquum on human tumor cell lines

Supplementary to the efficient inhibition of trypsin, chymotrypsin, plasma kallikrein, and plasmin already described by the EcTI inhibitor from Enterolobium contortisiliquum, it also blocks human neutrophil elastase (K(iapp)=4.3 nM) and prevents phorbol ester (PMA)-stimulated activation of matrix metalloproteinase (MMP)-2 probably via interference with membrane-type 1 (MT1)-MMP. Moreover, plasminogen-induced activation of proMMP-9 and processing of active MMP-2 was also inhibited. Furthermore, the effect of EcTI on the human cancer cell lines HCT116 and HT29 (colorectal), SkBr-3 and MCF-7 (breast), K562 and THP-1 (leukemia), as well as on human primary fibroblasts and human mesenchymal stem cells (hMSCs) was studied. EcTI inhibited in a concentration range of 1.0-2.5 μM rather specifically tumor cell viability without targeting primary fibroblasts and hMSCs. Taken together, our data indicate that the polyspecific proteinase inhibitor EcTI prevents proMMP activation and is cytotoxic against tumor cells without affecting normal tissue remodeling fibroblasts or regenerative hMSCs being an important tool in the studies of tumor cell development and dissemination.

Helix 8 plays a crucial role in bradykinin B(2) receptor trafficking and signaling

Upon activation the human bradykinin B(2) receptor (B(2)R) acts as guanine nucleotide exchange factor for the G proteins G(q/11) and G(i). Thereafter, it gets phosphorylated by G protein-coupled receptor kinases (GRKs) and recruits β-arrestins, which block further G protein activation and promote B(2)R internalization via clathrin-coated pits. As for most G protein-coupled receptors of family A, an intracellular helix 8 after transmembrane domain 7 is also predicted for the B(2)R. We show here that disruption of helix 8 in the B(2)R by either C-terminal truncation or just by mutation of a central amino acid (Lys-315) to a helix-breaking proline resulted in strong reduction of surface expression. Interestingly, this malfunction could be overcome by the addition of the membrane-permeable B(2)R antagonist JSM10292, suggesting that helix 8 has a general role for conformational stabilization that can be accounted for by an appropriate antagonist. Intriguingly, an intact helix 8, but not the C terminus with its phosphorylation sites, was indispensable for receptor sequestration and for interaction of the B(2)R with GRK2/3 and β-arrestin2 as shown by co-immunoprecipitation. Recruitment of β-arrestin1, however, required the presence of the C terminus. Taken together, our results demonstrate that helix 8 of the B(2)R plays a crucial role not only in efficient trafficking to the plasma membrane or the activation of G proteins but also for the interaction of the B(2)R with GRK2/3 and β-arrestins. Additional data obtained with chimera of B(2)R with other G protein-coupled receptors of family A suggest that helix 8 might have similar functions in other GPCRs as well.

Fever-like temperature modification differentially affects in vitro signaling of bradykinin B(1) and B(2) receptors

The bradykinin (BK) B(2) and B(1) receptors (B(2)R, B(1)R) belong to the rhodopsin-like G protein-coupled receptors (GPCRs) and are involved in (patho)physiological processes such as blood pressure regulation or inflammation. They mediate the effects of the pro-inflammatory peptides bradykinin/kallidin and desArg(9)-BK/desArg(10)-kallidin, respectively. Whereas the B(2)R is constitutively expressed and gets internalized upon activation, the B(1)R is especially induced by inflammatory mediators and responds to stimulation with increased surface receptor numbers. Stimulation of both receptors activates phospholipase Cβ (PLCβ) and mitogen activated protein kinase (MAPK) signaling. Because inflammatory processes are characterized by heat (fever), we analyzed the effect of increased temperature (41°C vs. 37°C) on B(1)R and B(2)R signaling in HEK 293 and IMR 90 cells. Our results show that signaling of both receptors is temperature-sensitive, however to a different extent and with regard to the investigated pathways. Comparing PLCβ activity and Ca(2+)-regulated signals, a temperature-dependent increase was only observed for B(1)R but not for B(2)R activation, whereas MAPK activities were doubled at 41°C for both receptors. Taken together, our findings suggest that the observed temperature sensitivity of B(1)R-induced PLCβ activation is B(1)R-specific. In contrast, the enhanced stimulation of MAPK activity under hyperthermic conditions appears to be a common phenomenon for GPCRs.

Reporter gene HEK 293 cells and WNT/Frizzled fusion proteins as tools to study WNT signaling pathways

WNT/Frizzled receptor (FZD) signaling pathways are pivotal for physiological and pathophysiological processes. In humans, the complexity of WNT/FZD signaling is based on 19 WNTs, 10 FZDs and at least two (co)receptors (LRP5/6) mediating supposably four different signaling cascades. The detailed investigation of the specific function of the different initiating components is primarily hampered by the lack of most WNT proteins in a purified form. Therefore, we constructed and examined a chimeric protein of WNT3a and FZD4 as a suitable approach to overcome this obstacle for future studies of the specificity of other WNT/FZD combinations. Furthermore, we produced four different reporter HEK 293 cell lines to quantify the induced activation of the proposed signaling cascades, the β-catenin-, the NFAT-, the AP-1- and the CRE-regulated pathways. The chimera WNT3aFZD4 efficiently induced β-catenin-mediated luciferase activity. This activity was increased 40-fold compared with basal when LRP6 was stably cotransfected, proving that the chimera WNT3aFZD4 can also interact efficiently with LRP6. Our results demonstrate that the approach of using reporter gene cell lines in combination with WNT/FZD chimeras is efficient to study the β-catenin-mediated pathway and should also allow clarifying the specificity of WNT/FZD combinations in the activation of the other pathways.

Cellular senescence induced by cathepsin X downregulation

Cellular senescence represents a powerful tumor suppressor mechanism to prevent proliferation and invasion of malignant cells. Since tumor cells as well as primary fibroblasts lacking the lysosomal cysteine-type carboxypeptidase cathepsin X exhibit a reduced invasive capacity, we hypothesized that the underlying reason may be the induction of cellular senescence. To investigate the cellular and molecular mechanisms leading to diminished migration/invasion of cathepsin X-deficient cells, we have analyzed murine embryonic fibroblasts (MEF) derived from cathepsin X-deficient mice and neonatal human dermal fibroblasts (NHDF) transfected with siRNAs targeting cathepsin X. Remarkably, both cell types exhibited a flattened and enlarged cell body, a characteristic phenotype of senescent cells. Additional evidence for accelerated senescence was obtained by detection of the common senescence marker β-galactosidase. Further examination revealed increased expression levels of senescence-associated genes such as p16, p21, p53, and caveolin in these cells along with a reduced proliferation rate. The accelerated cellular senescence induced by cathepsin X deficiency was rescued by simultaneous expression of exogenous cathepsin X. Finally, cell cycle analysis confirmed a marked reduction of the synthesis rate and prolongation of the S-phase, while susceptibility to apoptosis of cathepsin X-deficient cells remained unchanged. In conclusion, cathepsin X deficiency leads to accelerated cellular senescence and consequently to diminished cellular proliferation and migration/invasion implying a potential role of cathepsin X in bypassing cellular senescence.

Sulfur mustard induces differentiation in human primary keratinocytes: opposite roles of p38 and ERK1/2 MAPK

The chemical warfare agent sulfur mustard (SM) severely affects the regeneration capacity of skin. The underlying molecular and cellular mechanisms, however, are far from clear. Here, we demonstrate that normal human epidermal keratinocytes (NHEK) after exposure to SM strongly upregulated expression of keratin-1, involucrin, and loricrin, thus indicating premature epidermal differentiation. Furthermore, proliferation was repressed after treatment with SM. Analysis of intracellular signaling in NHEK revealed that SM enhances phosphorylation, nuclear translocation, and activity of the mitogen-activated protein kinases (MAPK) p38 and ERK1/2. Inhibition of p38 activity downregulated expression of keratin-1 and loricrin, whereas blockage of ERK1/2 significantly stimulated biosynthesis of these markers, pointing to opposite roles of p38 and ERK1/2 in the differentiation process. Simultaneous interruption of p38 and ERK1/2 activity led to a decreased expression of keratin-1 and loricrin. This suggests that NHEK differentiation is essentially controlled by p38 activity which may be negatively influenced by ERK1/2 activity. Functional analysis demonstrated that SM affects NHEK in their ability to migrate through extracellular matrix which can be rescued upon application of an inhibitor of p38 activity. Thus, our findings indicate that SM triggers premature differentiation in keratinocytes via p38 activity which may contribute to impaired regeneration of SM-injured skin.

Predictive relevance of clinical scores and inflammatory parameters in secondary peritonitis

HYPOTHESIS

To measure and evaluate clinical scores and various inflammation parameters for providing a better outcome assessment of patients with secondary peritonitis.

DESIGN

Prospective study.

SETTING

ICU of a university and a university affiliated hospital.

PATIENTS

Fifty-six patients with severe secondary peritonitis were enrolled in this study executed within 4 years.

MEASUREMENTS AND MAIN RESULTS

Blood samples were taken preoperatively and 2, 6, 8, 12, 18, 24, 30, 36, 42 and 48 hours post operation, thereafter every 12th hour until day 5 respectively once daily until day 14. Etiology of peritonitis, clinical score systems (APACHE II, MOF and SOFA), and 27 mainly with activity tests or enzyme-immunoassays measurable inflammation parameters were simultaneously analyzed and stratified into lethal outcome (n = 11) or survival (n = 45), respectively. The etiological distribution of peritonitis was identical among both groups. Proportion of intraperitoneal fungi, E. coli, and bacteroids was substantially higher during the primary operation in the group with lethal outcome. With increasing significance initial and follow-up APACHE II, MOF and SOFA scores provided higher values in this group. Various plasma/serum parameters of hemostasis, leukocyte proteolytic system, acute phase reaction, cytokine system, cell adhesion, opsonization, and main organ functions showed significantly different values between both groups at the preoperative stage and/or during observation period I (day 0-4). Logistic regression analysis revealed the SOFA score and neopterin concentration as the combination with the best sensitivity (63.6%) and specificity (93.2%) for predicting the patients' survival even at the preoperative stage. For the observation period I, the combination of SOFA score and TNF receptor II showed the highest predictive sensitivity (72.7%) and specificity (95.6%).

CONCLUSION

Evaluation of the severity of secondary peritonitis using a scoring system with high prognostic relevance could conceivably result in an earlier and adequate application of intensive care such as hemofiltration, administration of immunoglobulins and serial abdominal lavage to improve successful outcome.

Abstract 3539: Overexpression of the ATP Binding Cassette Gene ABCA1 determines resistance to curcumin in M14 melanoma cells

Background: Curcumin induces apoptosis in many cancer cells and it reduces xenograft growth and the formation of lung metastases in nude mice. Moreover, the plant derived polyphenol has been reported to be able to overcome drug resistance to classical chemotherapy. These features render the drug a promising candidate for tumor therapy especially for cancers known for their high rates concerning therapy resistance like melanoma.

Results: We show here that the melanoma cell line M14 is resistant to Curcumin induced apoptosis, which correlates with the absence of any effect on NFkappaB signaling. We show that CXCL1 a chemokine that is down regulated in breast cancer cells by Curcumin in an NFkappaB dependant manner is expressed at variable levels in human melanomas. Yet in M14 cells, CXCL1 expression did not change upon Curcumin treatment. Following the hypothesis that Curcumin is rapidly removed from the resistant cells, we analyzed expression of known multi drug resistance genes and cellular transporters in M14 melanoma cells and in the Curcumin sensitive breast cancer cell line MDA-MB-231. ATP-binding cassette transporter ABCA1, a gene involved in the cellular lipid removal pathway is over-expressed in resistant M14 melanoma as compared to the sensitive MDA-MB-231 breast cancer cells. Gene silencing of ABCA1 by siRNA sensitizes M14 cells to the apoptotic effect of Curcumin most likely as a result of reduced basal levels of active NFkappaB. Moreover, ABCA1 silencing alone also induces apoptosis and reduces p65 expression. Conclusion: Resistance to Curcumin thus follows classical pathways and ABCA1 expression should be considered as response marker.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3539.

Human osteoblast-derived factors induce early osteogenic markers in human mesenchymal stem cells

The capacity of human mesenchymal stem cells (hMSC) for self-renewal and differentiation is a tightly regulated process within their microenvironment--the stem cell niche. For future therapeutic applications of hMSC within the frame of tissue engineering, it is of major importance to understand the factors involved in triggering differentiation cascades of hMSC. Using either osteoblast-conditioned medium or an indirect coculture system, we investigated whether soluble factors from human osteoblasts (hOB) are sufficient to induce early osteogenic markers in hMSC. Thereby, we detected an induction of several osteogenic markers like alkaline phosphatase, bone sialoprotein 2, leptin receptor, decorin, and cathepsin K in hMSC as indicators of the onset of early osteogenesis. Further, because Wnt signaling has been reported to play an important role in osteogenesis, we performed RNAi against the main Wnt mediator beta-catenin and the low-density lipoprotein receptor-related protein 5 as a major Wnt co-receptor in hMSC. Whereas alkaline phosphatase was significantly downregulated with this approach, the other osteogenic markers showed a markedly upregulation. These observations suggest that hOB-secreted factors could induce early osteogenic markers in hMSC. Thus, with regard to a therapeutic setting, these findings may pave the way for a more in vivo-related differentiation procedure for the generation of osteoblast-like cells.

A cysteine-type carboxypeptidase, cathepsin X, generates peptide receptor agonists

The kallikrein-kinin system and the renin-angiotensin system interact at different levels and are linked by various molecules such as angiotensin-converting enzyme which degrades bradykinin into inactive peptides. Here we report that a cysteine-type carboxypeptidase, cathepsin X, is able to modulate the kallikrein-kinin system through carboxyterminal processing of the small peptide hormones bradykinin and kallidin. Both peptides are thereby converted from bradykinin B(2) receptor ligands to bradykinin B(1) receptor specific ligands. Cathepsin X, which has previously been recognized as an inflammatory marker may therefore act as a type I kininase. In addition, we have identified cathepsin X as an alternative possible link between the kallikrein-kinin system and the renin-angiotensin system in that it not only cleaves kinins C-terminally, but also converts angiotensin I to angiotensin II.

Early down-regulation of the pro-inflammatory potential of monocytes is correlated to organ dysfunction in patients after severe multiple injury: a cohort study

Introduction

Severe tissue trauma results in a general inflammatory immune response (SIRS) representing an overall inflammatory reaction of the immune system. However, there is little known about the functional alterations of monocytes in the early posttraumatic phase, characterized by the battle of the individual with the initial trauma.

Methods

Thirteen patients with severe multiple injury; injury severity score (ISS) >16 points (17 to 57) were included. The cytokine synthesis profiles of monocytes were characterized on admission, and followed up 6, 12, 24, 48, and 72 hours after severe multiple injury using flow cytometry. Whole blood was challenged with lipopolysaccharide (LPS) and subsequently analyzed for intracellular monocyte-related TNF-α, IL-1β, IL-6, and IL-8. The degree of organ dysfunction was assessed using the multiple organ dysfunction syndrome (MODS)-score of Marshall on admission, 24 hours and 72 hours after injury.

Results

Our data clearly show that the capacity of circulating monocytes to produce these mediators de novo was significantly diminished very early reaching a nadir 24 hours after severe injury followed by a rapid and nearly complete recovery another 48 hours later compared with admission and controls, respectively. In contrast to the initial injury severity, there was a significant correlation detectable between the clinical signs of multiple organ dysfunction and the ex vivo cytokine response.

Conclusions

As our data derived from very narrow intervals of measurements, they might contribute to a more detailed understanding of the early immune alterations recognized after severe trauma. It can be concluded that indeed as previously postulated an immediate hyperactivation of circulating monocytes is rapidly followed by a substantial paralysis of cell function. Moreover, our findings clearly demonstrate that the restricted capacity of monocytes to produce proinflammatory cytokines after severe injury is not only an in vitro phenomenon but also undistinguishable associated with the onset of organ dysfunction in the clinical scenario.

Alanine screening of the intracellular loops of the human bradykinin B receptor--effects on receptor maintenance, G protein activation and internalization

The bradykinin B(2) receptor is coupled to G protein G(q/11) and becomes sequestered into intracellular compartments after activation. To more closely define the receptor sequences involved in these processes and their functions, we systematically mutated all three intracellular loops (ICLs), either as point mutations or in groups of three to five amino acids to Ala, obtaining a total of 14 mutants. All constructs were stably expressed in HEK 293 cells and, with the exception of triple mutant DRY --> AAA, retained the ability to specifically bind [(3)H]bradykinin. The binding affinities at 4 or 37 degrees C of several mutants differed considerably from those determined for the wild-type receptor, indicating an allosteric connection between the conformation of the binding site and that of the ICLs. Mutations in ICL-1 strongly reduced surface expression without affecting G protein signaling or [(3)H]bradykinin internalization. Two cluster mutants in the middle of ICL-2 containing basic residues displayed considerably reduced potencies, whereas two mutations in ICL-3 resulted in receptor conformations that were considered to be semi-active, based on the observation that they responded with phosphoinositide hydrolysis to compounds normally considered to be antagonists. This, and the fact that a cluster mutant at the C-terminal end of ICL-3 was signaling incompetent, hint at the involvement of ICL-2 and ICL-3 in G(q/11) activation, albeit with different functions. None of the mutants displayed reduced ligand-induced receptor internalization, indicating that the loops are not essential for this process. No conclusion could be drawn, however, with regard to the role of the DRY sequence, as the corresponding triplet mutation lacked binding capability.

T-SP1: a novel serine protease-like protein predominantly expressed in testis

Here, we describe a novel member in the group of membrane-anchored chymotrypsin (S1)-like serine proteases, namely testis serine protease 1 (T-SP1), as it is principally expressed in testis tissue. The human T-SP1 gene encompasses 28.7 kb on the short arm of chromosome 8 and consists of seven exons. Rapid amplification of cDNA ends (RACE) experiments revealed that due to alternative splicing three different variants (T-SP1/1, -2, -3) are detectable in testis tissue displaying pronounced heterogeneity at their 3'-end. T-SP1/1 consists of an 18 amino acid signal peptide and of a 49 amino acid propeptide. The following domain with the catalytic triad of His(108), Asp(156), and Ser(250) shares sequence identities of 42% and 40% with the blood coagulation factor XI and plasma kallikrein, respectively. Only T-SP1/1 contains a hydrophobic part at the C-terminus, which provides the basis for cell membrane anchoring. Using a newly generated polyclonal anti-T-SP1 antibody, expression of the T-SP1 protein was found in the Leydig and Sertoli cells of the testis and in the epithelial cells of the ductuli efferentes. Notably, T-SP1 protein was also detectable in prostate cancer and in some ovarian cancer tissues, indicating tumor-related synthesis of T-SP1 beyond testis tissue.

Wnt signalling in mouse mesenchymal stem cells: impact on proliferation, invasion and MMP expression

Based on the capacity of mesenchymal stem cells (MSC) to differentiate into multiple cell types in vitro and in vivo, MCS may be a suitable source for cell therapy and regeneration strategies. A prerequisite for effective clinical applications of human MSC (hMSC) is a profound knowledge of signal transduction cascades that mediate processes like proliferation, targeted migration and differentiation. Recently, we identified the canonical Wnt signal transduction pathway as a key player in hMSC proliferation and invasion. To evaluate whether those findings are transferable to the equivalent counterparts in mice, we studied important steps in the wingless/int-1 (Wnt) signal transduction pathway in mouse MSC (mMSC) and mMSC carrying a T cell specific transcription factor (TCF)/lymphoid enhancer binding factor (LEF)-reporter transgene. We found that the induction of the canonical Wnt pathway resulted in the up-regulation of the known Wnt target gene cyclin D1, closely associated with an enhanced proliferation capacity of mMSC. Interestingly, the expression of the Wnt target gene membrane type 1-matrix metalloproteinase (MT1-MMP) was diminished in mMSC upon Wnt3a stimulation, which came along with an impaired invasion. In line with these findings, MMP-2 and MMP-9 expression levels in mMSC were also decreased after Wnt3a treatment. In contrast, inhibition of Wnt signalling by the knockdown of the transcriptional activator beta-catenin resulted in an up-regulation of MT1-MMP and mMSC invasion. By comparing these findings with the settings in hMSC, major differences in Wnt-regulated MMP expression were observed in mMSC. Thus, our data advice caution when mouse model systems represent the pre-clinical validation of MSC-mediated therapeutical approaches.

Lineage infidelity and expression of melanocytic markers in human breast cancer

In previous analyses, dual expression of melanocytic and epithelial molecular markers have been described as indicators of lineage infidelity for breast cancer cells that lose their epithelial identity. Here we demonstrated that this is a much more frequent phenomenon in human breast carcinomas, usually affecting only a part of the tumor. Accordingly we detected, in 18 out of 100 breast carcinomas, immunohistochemically focally positive cells for the melanocytic marker Melan A. The presence and extent of Melan A expression was statistically significantly associated with a reduction in tumor cell differentiation, but not tumor type, size, lymph node metastasis, hormone receptor status or Her-2-neu expression. Microarrays of a further 159 breast cancers showed, in several samples, variably low expression levels of Melan A (and other melanocytic markers) that are consistent with focal expression in many tumors. One case strongly overexpressed Melan A. The transition from an epithelial to a melanocytic phenotype (lineage infidelity) appears to occur much more frequently than previously assumed and occurs in restricted areas of breast cancer during tumor progression, a possible association with a reduction in tumor cell differentiation.

Matrix metalloproteinase-9 expression and release from skin fibroblasts interacting with keratinocytes: Upregulation in response to sulphur mustard

Matrix metalloproteinases (MMPs), especially MMP-9 and MMP-2, degrade various proteins of the extracellular matrix, including collagen type IV the major component of basement membranes which also separate the epidermis from the dermis. Although previous work indicates the contribution of MMPs and their inhibitors (TIMPs) to the pathophysiology of skin lesions induced by the toxic chemical warefare agent sulphur mustard (SM), little is known about the underlying molecular and cellular mechanisms. In this study we demonstrate in a 3D-skin model that topical application of SM significantly upregulated basal MMP-9 mRNA expression and release from the cells as shown by qRT-PCR and zymography, whereas that of MMP-2, membrane-type 1 (MT1)-MMP, TIMP-1 and TIMP-2 remained almost unaffected by SM. Further studies in neonatal human dermal fibroblasts (NHDF) and HaCaT keratinocytes revealed that MMP-9 was not secreted from these cells, neither with or without exposure to SM. However, when NHDF and HaCaT were cocultivated, MMP-9 was expressed and released from the cell mixture, suggesting that interaction between both cell types is essential for MMP-9 production. Moreover, SM-treatment of NHDF/HaCaT cocultures further upregulated MMP-9 biosynthesis and secretion, which was consistent with our findings obtained in the 3D-skin model. Addition of conditioned medium derived from SM-exposed HaCaT cells to NHDF was able to stimulate MMP-9 secretion and also increased the migratory potential of NHDF as shown in a scratch-wound healing assay and a fluorescent cell invasion assay. In contrast, culture supernatants of SM-treated NHDF had not such an effect on HaCaT cells. Taken together, our findings provide first evidence that SM exposure of skin stimulates keratinocytes to release soluble factors which in turn induce enhanced MMP-9 secretion and invasiveness of fibroblasts in vitro. This provides a potential mechanism probably contributing to SM-evoked tissue injury in vivo.

Sulfur mustard research--strategies for the development of improved medical therapy

OBJECTIVE

Sulfur mustard (SM) is a bifunctional alkylating substance being used as chemical warfare agent (vesicant). It is still regarded as a significant threat in chemical warfare and terrorism. Exposure to SM produces cutaneous blisters, respiratory and gastrointestinal tract injury, eye lesions, and bone marrow depression. Victims of World War I as well as those of the Iran-Iraq war have suffered from devastating chronic health impairment. Even decades after exposure, severe long-term effects like chronic obstructive lung disease, lung fibrosis, recurrent corneal ulcer disease, chronic conjunctivitis, abnormal pigmentation of the skin, and different forms of cancer have been diagnosed.

METHODS

This review briefly summarizes the scientific literature and own results concerning detection, organ toxicity of SM, its proposed toxicodynamic actions, and strategies for the development of improved medical therapy.

RESULTS

Despite extensive research efforts during the last century, efficient antidotes against SM have not yet been generated because its mechanism of action is not fully understood. However, deeper insights into these mechanisms gained in the last decade and promising developments of new drugs now offer new chances to minimize SM-induced organ damage and late effects.

CONCLUSION

Polymerase inhibitors, anti-inflammatory drugs, antioxidants, matrix metalloproteinase inhibitors, and probably regulators of DNA damage repair are identified as promising approaches to improve treatment.

Curcumin downregulates the inflammatory cytokines CXCL1 and -2 in breast cancer cells via NFkappaB

The dietary antioxidant Curcumin has been proposed for cancer chemoprevention since it induces apoptosis and inhibits the formation of breast cancer metastases. Curcumin acts through the inhibition of phosphorylation of the inhibitor of kappa B (IkappaB), which in turn reduces the nuclear translocation of nuclear factor kappa B (NFkappaB), an inflammation- and cell survival-related transcription factor. However, it is not clear whether the strong antimetastatic effect can exclusively be explained by inhibition of NFkappaB. Here, we addressed the effects of Curcumin (IC(50) = 17 muM) in MDA-MB-231 breast cancer cells using microarray gene expression analyses. Among the 62 genes whose expression was significantly altered, we found the two inflammatory cytokines CXCL1 and -2 (Groalpha and -beta) that were downregulated. Further validation of the microarray results by quantitative real-time reverse transcription-polymerase chain reaction, western blots and enzyme-linked immunosorbent assay revealed that Curcumin impairs transcription of CXCL1 and -2 >24 h and reduces the corresponding proteins. Using small interfering RNA techniques, we elucidated the underlying molecular mechanism revealing that reduction of CXCL1 and -2 messenger RNA levels is NFkappaB dependent and requires intact IkappaBalpha expression. Moreover, CXCL1 and -2 silencing leads to downregulation of several metastasis-promoting genes among which we found the cytokine receptor CXCR4. We therefore suggest that the decrease of CXCL1 and -2 mediated by Curcumin is involved in the inhibition of metastasis.

The Wnt signal transduction pathway in stem cells and cancer cells: influence on cellular invasion

The regulative network conducting adult stem cells in endogenous tissue repair is of prime interest for understanding organ regeneration as well as preventing degenerative and malignant diseases. One major signal transduction pathway which is involved in the control of these (patho)physiological processes is the Wnt pathway. Recent results obtained in our laboratories showed for the first time that canonical Wnt signaling is critically involved in the control of the migration/invasion behaviour of human mesenchymal stem cells (hMSC). In the first part of this review, we describe that the regenerative state is closely linked to the activation of the Wnt pathway. Central hallmarks of activated stem cells are recapitulated in a similar way also in cancer metastasis, where the acquisition of an invasive cancer stem cell phenotype is associated with the induction of Wnt-mediated epithelial to mesenchymal transition (EMT). In the second part, the influence of proinflammatory cytokines such as transforming growth factor (TGF-)beta1, interleukin (Il-)1beta, and tumor necrosis factor (TNF-)alpha is discussed with regard to the invasive characteristics of hMSC. In this context, special attention has been paid on the role of matrix metalloproteinases (MMPs), such as MMP-2, MMP-9 and membrane type 1 (MT1)-MMP, as well as on the tissue inhibitors of metalloproteinases TIMP-1 and TIMP-2. Putative cross-talks between different signal transduction pathways that may amplify the invasive capacity of this stem cell population are also discussed. Finally, the consequences towards future drug-mediated therapeutical modifications of Wnt signaling in stem cells and tumor cells are highlighted.

Identification of a novel 82 kDa proMMP-9 species associated with the surface of leukaemic cells: (auto-)catalytic activation and resistance to inhibition by TIMP-1

MMP-9 (matrix metalloproteinase 9) plays a critical role in tumour progression. Although the biochemical properties of the secreted form of proMMP-9 are well characterized, little is known about the function and activity of cell surface-associated proMMP-9. We purified a novel 82 kDa species of proMMP-9 from the plasma membrane of THP-1 leukaemic cells, which has substantial differences from the secreted 94 kDa proMMP-9. The 82 kDa form was not detected in the medium even upon stimulation with a phorbol ester. It is truncated by nine amino acid residues at its N-terminus, lacks O-linked oligosaccharides present in the 94 kDa proMMP-9, but retains N-linked carbohydrates. Incubation of 94 kDa proMMP-9 with MMP-3 generated the well-known 82 kDa active form, but the 82 kDa proMMP-9 was converted into an active species of 35 kDa, which was also produced by autocatalytic processing in the absence of activating enzymes. The activated 35 kDa MMP-9 efficiently degraded gelatins, native collagen type IV and fibronectin. The enzyme was less sensitive to TIMP-1 (tissue inhibitor of metalloproteinase 1) inhibition with IC50 values of 82 nM compared with 1 nM for the 82 kDa active MMP-9. The synthetic MMP inhibitor GM6001 blocked the activity of both enzymes, with similar IC50 values below 1 nM. The 82 kDa proMMP-9 is also produced in HL-60 and NB4 leukaemic cell lines as well as ex vivo leukaemic blast cells. It is, however, absent from neutrophils and mononuclear cells isolated from peripheral blood of healthy individuals. Thus, the 82 kDa proMMP-9 expressed on the surface of malignant cells may escape inhibition by natural TIMP-1, thereby facilitating cellular invasion in vivo.

Human mesenchymal stem cells at the single-cell level: simultaneous seven-colour immunofluorescence

Extracellular, intracellular or surface proteins can be used as putative markers to characterize human mesenchymal stem cells (hMSC). However, these markers are also expressed by other cell types and primary cell pools reveal considerable heterogeneity. Therefore, the simultaneous detection of several markers on a single cell appears to be an attractive approach to identify hMSC. Here we demonstrate the specific distinction of human MSC from human osteoblasts via seven-colour fluorescence on the single cell level with simultaneous marker detection of CD44, CD105/endoglin, CD106/VCAM-1, collagen-IV, fibronectin, actin and DAPI nuclear staining. We performed spectral image acquisition using a Sagnac-type interferometer. Subsequent linear unmixing allowed for decomposition of each pixel in its spectral components. Our approach reveals a typical expression profile of the adherent singular cells, allowing the specific distinction between hMSC and osteoblasts on the single cell level.

The chemopreventive polyphenol Curcumin prevents hematogenous breast cancer metastases in immunodeficient mice

Dissemination of metastatic cells probably occurs long before diagnosis of the primary tumor. Metastasis during early phases of carcinogenesis in high risk patients is therefore a potential prevention target. The plant polyphenol Curcumin has been proposed for dietary prevention of cancer. We therefore examined its effects on the human breast cancer cell line MDA-MB-231 in vitroand in a mouse metastasis model. Curcumin strongly induces apoptosis in MDA-MB-231 cells in correlation with reduced activation of the survival pathway NFkappaB, as a consequence of diminished IotakappaB and p65 phosphorylation. Curcumin also reduces the expression of major matrix metalloproteinases (MMPs) due to reduced NFkappa B activity and transcriptional downregulation of AP-1. NFkappa B/p65 silencing is sufficient to downregulate c-jun and MMP expression. Reduced NFkappa B/AP-1 activity and MMP expression lead to diminished invasion through a reconstituted basement membrane and to a significantly lower number of lung metastases in immunodeficient mice after intercardiac injection of 231 cells (p=0.0035). 68% of Curcumin treated but only 17% of untreated animals showed no or very few lung metastases, most likely as a consequence of down-regulation of NFkappa B/AP-1 dependent MMP expression and direct apoptotic effects on circulating tumor cells but not on established metastases. Dietary chemoprevention of metastases appears therefore feasible.

Analysis of Tissue Distribution of TNF- , TNF- -Receptors, and the Activating TNF- -Converting Enzyme Suggests Activation of the TNF- System in the Aging Intervertebral Disc

We immunohistochemically analyzed the expression and localization of TNF-alpha, its receptors TNF-RI and -RII, and the TNF-alpha-activating enzyme TACE in human autopsy (n=63) and surgical (n=35) lumbar intervertebral disc samples. In parallel, the TNF-alpha-mRNA was quantified by reverse transcriptase-polymerase chain reaction (RT-PCR). All samples were morphometrically evaluated for the proportion of positively labeled cells in the different anatomical regions of the disc. We detected a significant and comparable expression of all four parameters beginning in young adult age (c. 18 years) and being most extensive in the nucleus pulposus. This level was slightly reduced in older age discs. The annulus fibrosus contained significantly less labeled cells. In accord, the number of TNF-alpha-transcripts was elevated in most cases with immunohistochemical TNF-alpha expression. We provide clear evidence that TNF-alpha is expressed in discs of increasing age, which correlates with histomorphological signs of disc degeneration. In consequence, TNF-alpha seems to be activated (by the converting enzyme TACE) and biologically active through its receptors in human lumbar disc tissue.

Kinin receptors in stimulated and characterized decidua tissue-derived cells

Bradykinin and its kinin B(2) receptor are autocrine and paracrine mediators in foetal membranes and decidua. As a first step we characterized the intracellular morphology of decidual cells. Cultured decidua tissue-derived cells immunolabel for vimentin fibrils, and are considered to be of mesenchymal origin. They show characteristics of macrophages and can be distinguished from endothelial cells and cells of the trophoblast lineage. These cellular features were determined by means of immunocytochemistry. Furthermore cultured decidua tissue-derived cells express kinin B(2) receptors and in this context we demonstrated its expression at mRNA level by in situ reverse transcriptase polymerase chain reaction. Following stimulation with bacterial lipopolysaccharide, we have observed a marginal upregulation of the expression of kinin B(1) receptors and carboxypeptidase M by quantitative RT-PCR. Equilibrium binding experiments with [(3)H]des-Arg(10)-kallidin, the kinin B(1) receptor agonist, did not result in detectable binding sites.

MMP-2, MT1-MMP, and TIMP-2 are essential for the invasive capacity of human mesenchymal stem cells: differential regulation by inflammatory cytokines

Human mesenchymal stem cells (hMSCs) represent promising tools in various clinical applications, including the regeneration of injured tissues by endogenous or transplanted hMSCs. The molecular mechanisms, however, that control hMSC mobilization and homing which require invasion through extracellular matrix (ECM) barriers are almost unknown. We have analyzed bone marrow-derivedhMSCs and detected strong expression and synthesis of matrix metalloproteinase 2 (MMP-2), membrane type 1 MMP (MT1-MMP), tissue inhibitor of metalloproteinase 1 (TIMP-1), and TIMP-2. The ability of hMSCs to traverse reconstituted human basement membranes was effectively blocked in the presence of synthetic MMP inhibitors. Detailed studies by RNA interference revealed that gene knock-down of MMP-2, MT1-MMP, or TIMP-2 substantially impaired hMSC invasion, whereas silencing of TIMP-1 enhanced cell migration, indicating opposing roles of both TIMPs in this process. Moreover, the inflammatory cytokines TGF-beta1, IL-1beta, and TNF-alpha up-regulated MMP-2, MT1-MMP, and/or MMP-9 production in these cells, resulting in a strong stimulation of chemotactic migration through ECM, whereas the chemokine SDF-1alpha exhibited minor effects on MMP/TIMP expression and cell invasion. Thus, induction of specific MMP activity in hMSCs by inflammatory cytokines promotes directed cell migration across reconstituted basement membranes in vitro providing a potential mechanism in hMSC recruitment and extravasation into injured tissues in vivo.

Significance of Elecsys S100 immunoassay for real-time assessment of traumatic brain damage in multiple trauma patients

BACKGROUND

The neuroprotein S100 released into the circulation has been suggested as a reliable marker for primary brain damage. However, safe identification of relevant traumatic brain injury (TBI) may possibly be hampered by S100 release from peripheral tissue. The objective of this study was to measure early S100 levels using the Elecsys S100 immunoassay for real-time assessment of severe TBI in multiple trauma.

METHODS

Consecutively admitted multiple trauma patients (injury severity score >or=16 points) were stratified according to the results of the initial cerebral computed tomography (CCT) examination. S100 serum levels were determined at admission and at 6, 12, 24, 48 and 72 h after trauma. Data were correlated to creatine phosphokinase (CK) and lactate dehydrogenase (LDH) serum levels. Using receiver operating characteristic (ROC) analysis, the discriminating power of S100 measurement was calculated for the detection of CCT+ findings.

RESULTS

Median S100 levels of CCT+ patients (n=9; 37 years) decreased from 3.30 microg/L at admission to 0.41 microg/L 72 h after trauma. They revealed no significant differences to CCT- patients (n=18; 44 years), but remained elevated compared to controls. Median CK and LDH levels correlated with the corresponding S100 levels during the first 24 h after trauma. ROC analysis displayed a maximum area under the curve of only 0.653 at 12 h after trauma. No significant difference was calculated for the differentiation between CCT+ and CCT- patients.

CONCLUSIONS

Measurements of S100 serum levels using the Elecsys S100 immunoassay are not reliable for the real-time detection of severe TBI in multiple trauma patients. Due to soft tissue trauma or bone fractures, S100 is mainly released from peripheral sources such as adipocytes or skeletal muscle cells.

RGD-dependent binding of procathepsin X to integrin alphavbeta3 mediates cell-adhesive properties

Secreted lysosomal cysteine proteases (cathepsins) are involved in degradation and remodeling of the extracellular matrix, thus contributing to cell adhesion and migration. Among the eleven human lysosomal cysteine proteases, only procathepsin X contains an RGD motif located in a highly exposed region of the propeptide, which may allow binding of the proenzyme to RGD-recognizing integrins. Here, we have tested procathepsin X for cell-adhesive properties and found that it supports integrin alpha(v)beta(3)-dependent attachment and spreading of human umbilical vein endothelial cells. Using site-directed mutants of procathepsin X, we proved that this effect is mediated by the RGD sequence within the proregion of the protease. Endogenous procathepsin X is transported to the plasma membrane, accumulates in vesicles at lamellipodia of the human umbilical vein endothelial cell, and is partly associated with the cell surface, as shown by immunofluorescence. In addition, procathepsin X is partly co-localized with integrin beta(3), as detected by immunogold electron microscopy. A direct interaction between endogenous procathepsin X and alpha(v)beta(3) was demonstrated by co-immunoprecipitation. Moreover, surface plasmon resonance analysis revealed significant and RGD-dependent binding of procathepsin X to integrin alpha(v)beta(3). Our results provide for the first time evidence that the extracellular function of cathepsin X may include binding to integrins thereby modulating the attachment of migrating cells to ECM components.

C-terminal fusion of eGFP to the bradykinin B2 receptor strongly affects down-regulation but not receptor internalization or signaling

A functional comparison was made between the wild-type bradykinin B2 receptor (B2wt) and the chimera B2eGFP (enhanced green-fluorescent protein fused to the C-terminus of B2wt), both stably expressed in HEK 293 cells. There was almost no difference in terms of ligand-inducible receptor phosphorylation and internalization, signal transduction (accumulation of inositol phosphates) or expression and affinity. However, stimulation for up to 8 h with 10 microM bradykinin (BK) resulted in a strong decrease in surface receptors (by 60% within 5 h) in B2wt, but not in B2eGFP. When the expression levels of both constructs where comparably reduced using a weaker promoter, long-term stimulation resulted in a reduction in surface receptors for B2wt(low) to less than 20% within 1 h, whereas the chimera B2eGFP(low) still displayed 50% binding activity after 2 h. A 1-h incubation in the absence of BK resulted in a recovery of 60% of the binding in B2wt(low) after 1-h stimulation with BK, but of only 20% after 7-h stimulation. In contrast, B2eGFP(low) levels were restored to more than 70%, even after 7-h stimulation. These data indicate that although the fusion of eGFP to B2wt does not affect its ligand-induced internalization, it strongly reduces the down-regulation, most likely by promoting receptor recycling over degradation.

Identification of calpain cleavage sites in the G1 cyclin-dependent kinase inhibitor p19(INK4d)

Calpains are a large family of Ca2+-dependent cysteine proteases that are ubiquitously distributed across most cell types and vertebrate species. Calpains play a role in cell differentiation, apoptosis, cytoskeletal remodeling, signal transduction and the cell cycle. The cell cycle proteins cyclin D1 and p21(KIP1), for example, have been shown to be affected by calpains. However, the rules that govern calpain cleavage specificity are poorly understood. We report here studies on the pattern of mu-calpain proteolysis of the p19(INK4d) protein, a cyclin-dependent kinase 4/6 inhibitor that negatively regulates the mammalian cell cycle. Our data show new characteristics of calpain action: mu-calpain cleaves p19(INK4d) immediately after the first and second ankyrin repeats that are structurally less stable compared to the other repeats. This is in contrast to features observed so far in the specificity of calpains for their substrates. These results imply that calpain may be involved in the cell cycle by regulating the cell cycle regulatory protein turnover through CDK inhibitors and cyclins.

Serum S-100B protein levels during and after successful carotid artery stenting or carotid endarterectomy

PURPOSE

To characterize the course of S-100B serum levels, a reliable marker for cellular brain damage, in patients undergoing carotid artery stenting (CAS) or endarterectomy (CEA) for carotid artery stenosis compared to control groups undergoing hemithyroidectomy (HT) or coronary angiography (CA).

METHODS

Forty-six consecutive patients scheduled for revascularization of internal carotid artery (ICA) stenosis were included in the study. Fourteen patients (11 men; median age 70 years, interquartile range [IQR] 63-74) were selected for treatment with CAS, while CEA was performed in 31 patients (24 men; median age 68 years, IQR 54-78) during the same time period. Fourteen consecutive patients (8 men; median age 60 years, IQR 48-70) undergoing CA for suspected coronary heart disease and 14 patients (10 women; median age 36 years, IQR 26-54) undergoing HT for a single thyroid nodule served as controls.

RESULTS

All procedures were completed successfully. During ICA clamping in CEA patients without postoperative neurological deficits, median S-100B serum levels transiently increased from 0.04 to 0.26 ng/mL (p<0.01) and returned to baseline levels after declamping. Median S-100B serum levels of CAS patients without neurological impairment remained at baseline values. No increase in S-100B levels occurred in either control group. Three CEA patients who suffered from neurological deficits (1 transient ischemic attack and 1 major stroke) showed sustained elevation of S-100B serum levels 6 hours after extubation.

CONCLUSION

In patients without neurological complications, CEA but not CAS was associated with a transient increase in the S-100B serum levels. Results indicate that the increase in S-100B does not originate from extracerebral sources, but rather appears to represent an impairment of the blood-brain barrier integrity or subtle brain cell damage probably due to hypoperfusion during clamping. Sustained elevation of S-100B serum levels corresponded to the development of postoperative neurological deficits.

Wnt signaling regulates the invasion capacity of human mesenchymal stem cells

Human mesenchymal stem cells (hMSCs) exhibit the potential to contribute to a wide variety of endogenous organ tissue repair. However, the signals governing hMSC mobilization out of the bone marrow, release into the bloodstream, and migration/invasion into the target tissue are largely unknown. Since canonical Wnt signaling regulates not only tumor but also various stem cell attributes, we hypothesized that this signal transduction pathway might also be involved in governing the transmigration of hMSCs through human extracellular matrix (ECM). Stimulation of hMSCs with recombinant Wnt3a or LiCl resulted in the accumulation of the transcriptional activator beta-catenin, its translocation into the nucleus, and the upregulation of typical Wnt target genes such as cyclin D1 and membrane-type matrix metalloproteinase-1 (MT1-MMP). Moreover, both stimuli significantly enhanced hMSC proliferation up to 40%. In addition, an increase of more than twofold in the ability of hMSCs to transmigrate through Transwell filters coated with human ECM was observed. In a reverse approach, Wnt signaling in hMSCs was inhibited by knocking down the expression of either beta-catenin or low-density lipoprotein receptor-related protein 5 using RNA interference technology. These inhibition strategies resulted in downregulation of the Wnt target genes cyclin D1 and MT1-MMP, in a reduced proliferation rate, and in a strikingly diminished invasion capacity (64% and 52%). Taken together, this study provides for the first time decisive evidence that canonical Wnt signaling is critically involved in the regulation of the proliferation, as well as of the migration/invasion capacity of hMSCs, representing essential stem cell features indispensable during tissue regeneration processes.

SERUM S-100B CONCENTRATION PROVIDES ADDITIONAL INFORMATION FOT THE INDICATION OF COMPUTED TOMOGRAPHY IN PATIENTS AFTER MINOR HEAD INJURY

Ninety percent of patients with minor head injury (MHI) who have cranial computed tomography (CCT) under the present clinical decision rules have normal scans. Serum concentrations of the astroglial protein S-100B were recently found to provide useful information, but these studies were too small to provide a statistically safe basis for changing the present rule. We have investigated whether S-100B concentrations in patients with MHI can provide additional information to improve indication of the need for an initial CCT scan. One thousand three hundred nine patients with MHI were enrolled in this prospective, multicenter study. All had a CCT scan to confirm diagnosis in accordance with the present clinical decision rules. S-100B was measured in serum samples obtained upon admission. Data were analyzed using contingency table and receiver operating characteristic curve and compared with those for healthy donors (n = 540) and with those for patients with moderate to severe head injury (n = 55). Of the 1309 patients studied, 93 exhibited trauma-relevant intracerebral lesions on the CCT scan (CCT+). With a cutoff limit of 0.10-microg/L S-100B (95th percentile of values in healthy volunteers), CCT+ patients were identified with a sensitivity level of 99% (95% confidence interval, 96% - 100%) and a specificity level of 30% (95% confidence interval, 29% - 31%). Adding the measurement of S-100B concentration to the clinical decision rules for a CCT scan in patients with MHI could allow a 30% reduction in scans. A prospective study of the clinical value of S-100B measurement in such patients is now under way.

Modulation of autocrine TNF-alpha-stimulated matrix metalloproteinase 9 (MMP-9) expression by mitogen-activated protein kinases in THP-1 monocytic cells

Matrix metalloproteinase 9 (MMP-9) is implicated in various physiological processes by its ability to degrade the extracellular matrix (ECM) and process multiple regulatory proteins. Normally, MMP-9 expression is tightly controlled in cells. Sustained or enhanced MMP-9 secretion, however, has been demonstrated to contribute to the pathophysiology of numerous diseases, including arthritis and tumor progression, rendering this enzyme a major target for clinical interventions. Here we show that constitutive MMP-9 secretion was abrogated in THP-1 monocytic leukemia cells by addition of neutralizing antibodies against tumor necrosis factor alpha (TNF-alpha) or TNF receptor type 1 (TNF-R1), as well as by inhibition of TNF-alpha converting enzyme (TACE). This indicates that MMP-9 production in these cells is maintained by autocrine stimulation, with TNF-alpha acting via TNF-R1. To investigate the intracellular signaling routes involved in MMP-9 gene transcription, cells were treated with different inhibitors of major mitogen-activated protein kinase (MAPK) pathways. Interruption of the extracellular signal-regulated kinase pathway 1/2 (ERK1/2) using PD98059 significantly downregulated constitutive MMP-9 release. In contrast, blockage of p38 kinase activity by addition of SB203580 or SB202190, as well as inhibition of c-Jun N-terminal kinase (JNK) using L-JNK-I1, clearly augmented MMP-9 expression and secretion by an upregulation of ERK1/2 phosphorylation. Moreover, exogenously added TNF-alpha augmented MMP-9 synthesis and secretion in THP-1 cells via enhancement of ERK1/2 activity. Taken together, our results indicate that ERK1/2 activity plays a pivotal role in TNF-alpha-induced MMP-9 production and demonstrate its negative modulation by p38 and JNK activity. These findings suggest ERK1/2 rather than p38 and JNK as a reasonable target to specifically block MMP-9 expression using MAPK inhibitors in therapeutic applications.

Rapid measurement of S-100B serum protein levels by Elecsys S100 immunoassay in patients undergoing carotid artery stenting or endarterectomy

OBJECTIVES

This study was designed to apply the rapid Elecsys S100 immunoassay for real-time measurement of S100 protein serum levels indicating acute brain damage in patients undergoing carotid artery stenting (CAS) or endarterectomy (CEA).

DESIGN AND METHODS

Data of 14 CAS patients were compared to those of 43 CEA and 14 control patients undergoing coronary angiography (CA). S100 serum levels were measured by the full-automatic Elecsys S100 immunoassay and compared to those obtained by the well-established LIA-mat S100 system.

RESULTS

In contrast to CAS and CA patients, median S100 serum levels of CEA patients significantly increased to 0.24 ng/mL before declamping, but subsequently returned to baseline. Three CEA patients with neurological deficits showed sustained elevated S100 levels 6 h after extubation. Absolute S100 values were not significantly different between the two methods. Bland-Altman plot analyses displayed a good agreement, mostly indicating slightly smaller values applying the Elecsys S100 system.

CONCLUSIONS

The Elecsys S100 system appears to be suitable for rapid real-time detection of neurological deficits in patients undergoing CAS and CEA. Persistent elevations of Elecsys S100 levels during CEA were associated with prolonged neurological disorders, whereas transient increases seem to represent impaired blood-brain barrier integrity without neurological deficits.

Matrix metalloproteinases in cancer: comparison of known and novel aspects of their inhibition as a therapeutic approach

Matrix dissolution is a crucial step during tumor progression that converts a premalignant cell to an overtly malignant one. Main players in this step are the various matrix metalloproteinases (MMPs), which differ in substrate specificity and tissue distribution, and thereby also differ in presence and function during various stages of initial and systemic tumor spread. Accordingly, the inhibition of MMP synthesis and/or activity represents novel potential therapeutic strategies for the treatment of cancer patients. Considerable work has already been carried out on synthetic inhibitors of MMP activity, but with little or even adverse effects in recent clinical studies. The reasons may be inappropriate patient populations in too advanced tumor stages, or inappropriate enzymes as targets for inhibition. Upregulation of endogenous tissue inhibitors of MMP (TIMPs) also provided ambiguous results, since TIMPs possess biologic functions in addition to MMP inhibition, for example, TIMP-2 is a main player in the MMP-2 activation cascade. This may explain, at least in part, the adverse effects of TIMP application/upregulation. Other strategies have been sought in order to overcome these problems. These include the downregulation of MMP transcription by cytokines. However, the effects of cytokines (other than MMP inhibition) may also limit the use of this approach. Finally, empiric evidence for control and modulation of MMP transcription and/or activation by several naturally occurring substances, such as flavonoids, green tea polyphenols and curcumin, represent novel options for the control of MMP activity even in early tumor stages. Additionally, these substances have little or no toxic side effects and good bioavailability, and therefore their continuing analysis provides intriguing insight into tumor pathophysiology and possibly new therapeutic options.

Measurement of S-100B for risk classification of victims sustaining minor head injury--first pilot study in Brazil

BACKGROUND

Release of the neuronal protein S-100B into the circulation has been suggested as a specific indication of neuronal damage. The hypothesis that S-100B is a useful and cost-effective screening tool for the management of minor head injuries was tested.

METHODS

Fifty consecutive patients sustaining isolated minor head injury were prospectively evaluated in the emergency room of a Brazilian hospital by routine cranial computed tomography scan. Venous blood samples (processed to serum) were assayed for S-100B using a newly developed immunoassay test kit. Twenty-one normal healthy individuals served as negative controls. Data are presented as median and 25 to 75 percentiles.

RESULTS

Patients reached the emergency room an average of 45 minutes (range: 30-62 minutes) after minor head injury. Six of 50 patients (12%) showed relevant posttraumatic lesions in the initial cranial computed tomography scan and were counted as positive. The median systemic concentration of S-100B in those patients was 0.75 microg/L (range: 0.66-6.5 microg/L), which was significantly different (U-test, P < .05) from the median concentration of 0.26 microg/L (range: 0.12-0.65 microg/L), of patients without posttraumatic lesions as counted by the cranial computed tomography. A sensitivity of 100%, a specificity of 20%, a positive predictive value of 15%, and a negative predictive value of 100% was calculated for the detection of patients suffering from intracranial lesions.

CONCLUSIONS

Protein S-100B had a very high sensitivity and negative predictive value and could have an important role in ruling out the need for cranial computed tomography scan after minor head injury. This appears to be of substantial clinical relevance, particularly in countries where trauma incidence is high and medical resources are limited, such as in Brazil.

An enzyme-linked immunosorbent assay for human cathepsin X, a potential new inflammatory marker

The human lysosomal cysteine-type carboxypeptidase cathepsin X is mainly present in monocytes and macrophages and may be released into the circulation due to constitutive and/or regulated secretion by (activated) immune cells. To define its potential diagnostic value as an inflammatory marker, we have developed a highly sensitive and specific sandwich-type immunoassay (ELISA) for cathepsin X permitting both intra- and extracellular detection and quantification. The dynamic range of the cathepsin X ELISA was determined to be 100 (detection limit) to 8000 pg/ml. Reproducibility of both within and between runs yielded coefficients of variation (CVs) of 2.7-3.5% and 6.3-7.3%, respectively. Cross-reactivity with other members (cathepsin B, L) of the thiol-dependent cathepsin family was not observed. The ELISA was used to quantify cathepsin X in leukocytes as well as in plasma of healthy volunteers and patients with multiple trauma. During the first 72 h after trauma, plasma levels of cathepsin X increased significantly, particularly in patients who died during the posttraumatic period. In comparison to the well-known inflammation marker neutrophil elastase, cathepsin X levels predicted survival with a higher significance in the later posttraumatic phase. In conclusion, this report provides the first evidence of cathepsin X immunoreactivity not only in cell lysates but also in plasma samples. We suggest that the newly developed highly reproducible ELISA will be of great value for further evaluation of this protease as a diagnostic and/or prognostic marker in inflammatory diseases.

Genome-wide monocytic mRNA expression in polytrauma patients for identification of clinical outcome

Immune activation in multiple trauma is closely linked to the development of multiple organ dysfunction and failure, and consequently, has a profound influence on patient outcome. Although peripheral blood monocytes play a critical role in this immune response, the biological significance of changes in genome-wide expression immediately after traumatic injury have not been explored previously. Thirteen patients presenting with multiple blunt trauma were studied. Peripheral blood monocytes were obtained within 90 min and at 6, 12, 24, 48, and 72 h after trauma. Apparent genome-wide expression was determined with Affymetrix U133A microarrays. Supervised analysis identified 698 probe sets that were differentially expressed in the 13 trauma subjects (P < 0.001) over the 72-h study period. An additional 763 probe sets were differentially expressed in patients who died (n = 3) compared with those who survived (n = 10). The ability of these probe sets to function as a classifier of survival was significantly demonstrated with six prediction models. Using pathway analysis, a network of proinflammatory genes and intracellular signaling pathways leading to c-JUN activation were consistently overexpressed in patients who died. Genome-wide mRNA expression patterns in circulating peripheral blood monocytes from multiple-injured patients can discriminate clinical outcome. The pattern of gene expression in patients who died suggests that in these individuals, there is a reprioritization of gene expression consistent with an early activation of selected genes involved in the initiation and propagation of a proinflammatory response.

μ-Calpain binds to lipid bilayers via the exposed hydrophobic surface of its Ca2+-activated conformation

Mu- and m-calpain are cysteine proteases requiring micro- and millimolar Ca2+ concentrations for their activation in vitro. Among other mechanisms, interaction of calpains with membrane phospholipids has been proposed to facilitate their activation by nanomolar [Ca2+] in living cells. Here the interaction of non-autolysing, C115A active-site mutated heterodimeric human mu-calpain with phospholipid bilayers was studied in vitro using protein-to-lipid fluorescence resonance energy transfer and surface plasmon resonance. Binding to liposomes was Ca2+-dependent, but not selective for specific phospholipid head groups. [Ca2+]0.5 for association with lipid bilayers was not lower than that required for the exposure of hydrophobic surface (detected by TNS fluorescence) or for enzyme activity in the absence of lipids. Deletion of domain V reduced the lipid affinity of the isolated small subunit (600-fold) and of the heterodimer (10- to 15-fold), thus confirming the proposed role of domain V for membrane binding. Unexpectedly, mutations in the acidic loop of the 'C2-like' domain III, a putative Ca2+ and phospholipid-binding site, did not affect lipid affinity. Taken together, these results support the hypothesis that in vitro membrane binding of mu-calpain is due to the exposed hydrophobic surface of the active conformation and does not reduce the Ca2+ requirement for activation.

Bilateral lavage with diluted surfactant improves lung function after unilateral lung contusion in pigs*

OBJECTIVE

This study evaluates the effects of bronchoalveolar lavage with diluted surfactant on unilateral lung contusion-induced lung dysfunction.

DESIGN

Randomized prospective animal study.

SETTING

An animal laboratory.

SUBJECTS

Twenty adult pigs, weighing 25-35 kg.

INTERVENTIONS

Animals were randomly assigned to controls and surfactant treatment. Bilateral lavage with surfactant treatment began 30 mins after unilateral lung contusion. Then 25 mg/kg of body weight diluted Curosurf (5 mg/mL) was applied in a volume of 5 mL/kg of body weight. Observation time was 8 hrs postinjury.

MEASUREMENTS AND MAIN RESULTS

The Pao2/Fio2 ratio fell from 500 to 250 and then recovered gradually in controls and surfactant-treated pigs. After another 4 hrs, the Pao2/Fio2 ratio deteriorated again in controls, but not in surfactant-treated animals. Total compliance fell by 50% after injury but was completely restored by surfactant treatment. Lung contusion increased the median number of neutrophils in bronchoalveolar lavage fluid from 2% to 30% of total cells and peaked >60% at 480 mins in the contused lungs of control pigs. Surfactant-treated pigs had 40% neutrophils at 480 mins without reaching significant difference to controls. The leukocyte neutral proteinase inhibitor increased to 500 ng/mL at 30 mins postinjury in the contused lungs and increased to 2000 ng/mL after surfactant treatment.

CONCLUSIONS

Bilateral bronchoalveolar lavage with diluted surfactant can effectively improve lung function after experimental unilateral lung contusion in pigs.