Acute‐phase serum amyloid A stimulation of angiogenesis,leukocyte recruitment,and matrix degradation in rheumatoid arthritis through an NF‐κB–dependent signal transduction pathway

Objective

To examine the role of the acute‐phase protein serum amyloid A (A‐SAA) in regulating cell adhesion molecule expression, leukocyte recruitment, and angiogenesis in rheumatoid arthritis (RA).

Methods

Intercellular adhesion molecule 1 (ICAM‐1), vascular cell adhesion molecule 1 (VCAM‐1), and matrix metalloproteinase 1 (MMP‐1) expression was examined in RA fibroblast‐like synoviocytes (FLS) and human microvascular endothelial cells (HMVECs) using flow cytometry and enzyme‐linked immunosorbent assay techniques. Peripheral blood mononuclear cell (PBMC) adhesion to FLS/HMVECs was determined by flow cytometry. Angiogenesis was examined using a Boyden chemotaxis chamber and Matrigel tubule formation. NF‐κB/IκBα mediation of the effects of A‐SAA was investigated using a specific NF‐κB inhibitor and Western blotting.

Results

A‐SAA significantly enhanced the time‐ and dose‐dependent expression of ICAM‐1 and VCAM‐1 as effectively as interleukin‐1β/tumor necrosis factor α. A‐SAA promoted the adhesion of PBMCs to FLS and HMVECs. In addition, A‐SAA at 10 μg/ml and 50 μg/ml significantly increased endothelial cell tube formation by 69% and 207%, respectively. At 50 μg/ml and 100 μg/ml, A‐SAA increased HMVEC migration by 188 ± 54% and 296 ± 71%, respectively (mean ± SEM). A‐SAA–induced expression of VCAM‐1, ICAM‐1, and MMP‐1 was down‐regulated by NF‐κB inhibition. Furthermore, A‐SAA induced IκBα degradation and NF‐κB translocation, suggesting that its proinflammatory effects are mediated in part by NF‐κB signaling.

Conclusion

Our findings demonstrate the ability of A‐SAA to induce adhesion molecule expression, angiogenesis, and matrix degradation, mechanisms that are mediated by NF‐κB. Targeting A‐SAA and its signaling pathways may represent a new therapeutic approach in the treatment of RA.

     

RhoA‐mediated,tumor necrosis factor α–induced activation of NF‐κB in rheumatoid synoviocytes: Inhibitory effect of simvastatin

Objective

Increasing evidence indicates that RhoA may play a central role in the inflammatory response. This study was conducted to examine the role of RhoA in mediating the activation of NF‐κB in tumor necrosis factor α (TNFα)–stimulated rheumatoid synoviocytes, and to evaluate the modulatory effects of statins on the TNFα‐induced activation of RhoA and NF‐κB and the secretion of proinflammatory cytokines by rheumatoid synoviocytes.

Methods

Rheumatoid synoviocytes obtained from patients with active rheumatoid arthritis were stimulated with TNFα and incubated with simvastatin (SMV) (1 μM). RhoA activity was assessed by a pull‐down assay. NF‐κB DNA binding activity and nuclear translocation of NF‐κB were measured by a sensitive multiwell colorimetric assay and confocal fluorescence microscopy, respectively.

Results

TNFα stimulation elicited a robust increase in RhoA activity in a dose‐dependent manner, and SMV mitigated this increase. TNFα also hastened NF‐κB nuclear translocation of subunit p65 and increased DNA binding activity, luciferase reporter gene expression, degradation of IκB, and secretion of interleukin‐1β (IL‐1β) and IL‐6. SMV prevented the increase in NF‐κB activation and rise in IL‐1β and IL‐6 levels induced by TNFα, whereas mevalonate and geranylgeranyl pyrophosphate reversed the inhibitory effects of SMV on activation of NF‐κB and RhoA. Furthermore, cotransfection with a dominant‐negative mutant of RhoA demonstrated that the TNFα‐induced signaling pathway involved sequential activation of RhoA, leading to NF‐κB activation and, ultimately, to secretion of cytokines.

Conclusion

This study identifies RhoA as the key regulator of TNFα‐induced NF‐κB activation, which ultimately results in the secretion of proinflammatory cytokines in rheumatoid synoviocytes. The findings provide a new rationale for the antiinflammatory effects of statins in inflammatory arthritis.

     

PTX3 in small‐vessel vasculitides: An independent indicator of disease activity produced at sites of inflammation

Objective

To verify whether the prototypical long pentraxin PTX3 represents an indicator of the activity of small‐vessel vasculitis.

Methods

Concentrations of PTX3, a pentraxin induced in endothelium by cytokines, were measured by enzyme‐linked immunosorbent assay in the sera of 43 patients with Churg‐Strauss syndrome, Wegener's granulomatosis, and microscopic polyangiitis. PTX3 was also measured in the sera of 28 patients with systemic lupus erythematosus (SLE), 22 with rheumatoid arthritis, and 16 with CREST syndrome (calcinosis, Raynaud's phenomenon, esophageal dysmotility, sclerodactyly, telangiectasias). Serum concentrations of C‐reactive protein (CRP) were measured by immunoturbidimetry. The cells involved in PTX3 production in vivo were identified in skin biopsy samples.

Results

Patients with active vasculitis had significantly higher concentrations of PTX3 than did those with quiescent disease (P < 0.001). PTX3 levels in the latter group were similar to those in healthy controls. PTX3 levels were higher in patients with untreated vasculitis and lower in patients who underwent immunosuppressive treatments (P < 0.005). In contrast, patients with active SLE had negligible levels of the pentraxin. PTX3 levels did not correlate with CRP levels in vasculitis patients. Endothelial cells produced PTX3 in active skin lesions.

Conclusion

PTX3 represents a novel acute‐phase reactant produced at sites of active vasculitis.

     

The proinflammatory activity of recombinant serum amyloid A is not shared by the endogenous protein in the circulation

Objective

Elevated serum levels of the acute‐phase protein serum amyloid A (SAA) are a marker for active rheumatoid arthritis (RA), and SAA can also be found in the tissues of patients with active RA. Based on a number of studies with recombinant SAA (rSAA), the protein has been suggested to be a potent proinflammatory mediator that activates human neutrophils, but whether endogenous SAA shares these proinflammatory activities has not been directly addressed. The present study was undertaken to investigate whether SAA in the plasma of patients with RA possesses proinflammatory properties and activates neutrophils in a manner similar to that of the recombinant protein.

Methods

Neutrophil activation was monitored by flow cytometry, based on L‐selectin shedding from cell surfaces. Whole blood samples from healthy subjects and from RA patients with highly elevated SAA levels were studied before and after stimulation with rSAA as well as purified endogenous SAA.

Results

Recombinant SAA potently induced cleavage of L‐selectin from neutrophils and in whole blood samples. Despite highly elevated SAA levels, L‐selectin was not down‐regulated on RA patient neutrophils as compared with neutrophils from healthy controls. Spiking SAA‐rich whole blood samples from RA patients with rSAA, however, resulted in L‐selectin shedding. In addition, SAA purified from human plasma was completely devoid of neutrophil‐ or macrophage‐activating capacity.

Conclusion

The present findings show that rSAA is proinflammatory but that this activity is not shared by endogenous SAA, either when present in the circulation of RA patients or when purified from plasma during an acute‐phase response.

     

Layilin, a talin-binding hyaluronan receptor, is expressed in human articular chondrocytes and synoviocytes and is down-regulated by interleukin-1β

Objective

Layilin (LAYN), a 55-kDa transmembrane protein with homology to C-type lectins, has been identified as a receptor of hyaluronan (HA). Interestingly, LAYN does not share any sequence homology with CD44, a primary HA receptor. The primary aim of our study was to examine the expression and potential function of LAYN in human articular chondrocytes and synoviocytes.

Methods

Samples were obtained from patients undergoing joint arthroplasty. Cells were grown in vitro, then stimulated with interleukin (IL)-1β or tumor necrosis factor alpha (TNFα) for 24 h and the expression of LAYN was analyzed. To assess the function of LAYN, we transfected chondrocytes with siRNA against LAYN, treated them with HA and IL-1β, and then analyzed the production of matrix metalloproteinase (MMP)-1 and MMP-13 in the treated chrondrocytes.

Results

The results showed that LAYN was constitutively expressed in human articular chondrocytes and synoviocytes and that IL-1β significantly suppressed the expression of LAYN in these cells. HA repressed IL-1β-induced MMP-1 and MMP-13 production in chondrocytes, but this was significantly abrogated in chondrocytes transfected with siRNA against LAYN.

Conclusions

Our results show that human chondrocytes express LAYN, a novel HA receptor, and that LAYN may contribute to the regulation of HA functions in the arthritic condition. Further investigation of the HA receptor may lead to the development of novel therapeutics to regulate HA signaling in inflammatory arthritis.     

Modulation of interleukin‐6 and matrix metalloproteinase 2 expression in human fibroblast‐like synoviocytes by functional ionotropic glutamate receptors

Objective

Patients with rheumatoid arthritis (RA) have increased concentrations of the amino acid glutamate in synovial fluid. This study was undertaken to determine whether glutamate receptors are expressed in the synovial joint, and to determine whether activation of glutamate receptors on human synoviocytes contributes to RA disease pathology.

Methods

Glutamate receptor expression was examined in tissue samples from rat knee joints and in human fibroblast‐like synoviocytes (FLS). FLS from 5 RA patients and 1 normal control were used to determine whether a range of glutamate receptor antagonists influenced expression of the proinflammatory cytokine interleukin‐6 (IL‐6), enzymes involved in matrix degradation and cytokine processing (matrix metalloproteinase 2 [MMP‐2] and MMP‐9), and the inhibitors of these enzymes (tissue inhibitor of metalloproteinases 1 [TIMP‐1] and TIMP‐2). IL‐6 concentrations were determined by enzyme‐linked immunosorbent assay, MMP activity was measured by gelatin zymography, and TIMP activity was determined by reverse zymography. Fluorescence imaging of intracellular calcium concentrations in live RA FLS stimulated with specific antagonists was used to reveal functional activation of glutamate receptors that modulated IL‐6 or MMP‐2.

Results

Ionotropic and metabotropic glutamate receptor subunit mRNA were expressed in the patella, fat pad, and meniscus of the rat knee and in human articular cartilage. Inhibition of N‐methyl‐D ‐aspartate (NMDA) receptors in RA FLS increased proMMP‐2 release, whereas non‐NMDA ionotropic glutamate receptor antagonists reduced IL‐6 production by these cells. Stimulation with glutamate, NMDA, or kainate (KA) increased intracellular calcium concentrations in RA FLS, demonstrating functional activation of specific ionotropic glutamate receptors.

Conclusion

Our findings indicate that activation of NMDA and KA glutamate receptors on human synoviocytes may contribute to joint destruction by increasing IL‐6 expression.

     

Cadherin 11 promotes invasive behavior of fibroblast‐like synoviocytes

Objective

To define the expression pattern of cadherin 11 in the destructive pannus tissue of patients with rheumatoid arthritis, and to determine whether cadherin 11 expression in fibroblast‐like synoviocytes controls their invasive capacity.

Methods

Cadherin 11 expression in rheumatoid synovial tissue was evaluated using immunohistochemistry. To examine the role of cadherin 11 in regulating the invasive behavior of fibroblast‐like synoviocytes, we generated L cell clones expressing wild‐type cadherin 11, mutant cadherin 11, and empty vector–transfected controls. The invasive capacity of L cell transfectants and cultured fibroblast‐like synoviocytes treated with a blocking cadherin 11–Fc fusion protein or control immunoglobulin was determined in Matrigel invasion assays.

Results

Immunohistochemical analysis revealed that cadherin 11 is abundantly expressed in cells at the cartilage–pannus junction in rheumatoid synovitis. Assays to determine invasion demonstrated a 2‐fold increased invasive capacity of cadherin 11–transfected L cells compared with L cells transfected with E‐cadherin or control vector. The invasive behavior of L cells stably transfected with a cadherin 11 construct that lacked the juxtamembrane cytoplasmic domain was diminished to the level of vector control L cells. Furthermore, treatment with the cadherin 11–Fc fusion protein diminished the invasive capacity of fibroblast‐like synoviocytes.

Conclusion

The results of these in vitro studies implicate a role for cadherin 11 in promoting cell invasion and contribute insight into the invasive nature of fibroblast‐like synoviocytes in chronic synovitis and rheumatoid arthritis.

     

T cell costimulation by fractalkine‐expressing synoviocytes in rheumatoid arthritis

Objective

Patients with rheumatoid arthritis (RA) accumulate prematurely aged T cells that have acquired a new profile of regulatory receptors. Many of the de novo–expressed receptors are typically found on natural killer cells, including CX₃CR1, the receptor for the chemokine fractalkine (FKN). This study explored whether interactions between CX₃CR1 and FKN are relevant for T cell functions in rheumatoid synovitis.

Methods

FKN expression was examined by real‐time polymerase chain reaction and immunohistochemistry. CX₃CR1 expression on peripheral blood T cells was analyzed by flow cytometry. T cell activation was quantified by determining proliferative responses, interferon‐γ (IFNγ) secretion, and granule release. Fibroblast‐like synoviocyte (FLS)/T cell adhesion was measured by the retention of 5‐carboxyfluorescein diacetate succinimidyl ester–labeled T cells on FLS monolayers.

Results

FKN was expressed on cultured synovial fibroblasts and hyperplastic synoviocytes in the rheumatoid tissue. Among CD4+ T cells, only senescent CD28− T cells were positive for CX₃CR1 (P < 0.001). Such CD4+,CD28−,CX₃CR1+ T cells strongly adhered to FLS, with soluble FKN blocking the interaction. FKN expressed on FLS costimulated T cell–activating signals and amplified proliferation, IFNγ production, and expulsion of cytoplasmic granules.

Conclusion

Senescent CD4+ T cells that accumulate in rheumatoid arthritis aberrantly express CX₃CR1. FKN, which is membrane‐anchored on synoviocytes, enhances CD4+ T cell adhesion, provides survival signals, and costimulates the production of proinflammatory cytokines as well as the release of granules. By virtue of their altered receptor profile, senescent CD4+ T cells receive strong stimulatory signals from nonprofessional antigen‐presenting cells in the synovial microenvironment.

     

Antiviral gene expression in rheumatoid arthritis: Role of IKKϵ and interferon regulatory factor 3

Objective

The rheumatoid synovium displays characteristics of Toll‐like receptor (TLR) activation and antiviral gene expression, including production of RANTES and interferon‐β (IFNβ). The mechanism of this activation in rheumatoid synovial tissue is unknown. This study was designed to investigate the role of the IKK‐related kinase IKKϵ and IFN regulatory factor 3 (IRF‐3) in the activation of antiviral genes in rheumatoid arthritis (RA).

Methods

Kinase assay and immunostaining were performed on synovial tissue. Dominant‐negative (DN) IKKϵ adenoviral infection of human fibroblast‐like synoviocytes (FLS) was followed by poly(I‐C) stimulation and Western blotting. Quantitative polymerase chain reaction was performed on DN IKKϵ–infected FLS and IKKϵ^−/− and IKKϵ^+/+ mouse FLS.

Results

Western blotting showed that IKKϵ phosphorylation was significantly greater in RA synovium compared with osteoarthritis synovium. Kinase assay confirmed that IKKϵ was activated in RA synovium, and immunostaining showed localization of pIKKϵ to the intimal lining. Western blot analysis demonstrated that activation of IRF‐3 was also increased in RA synovium. Poly(I‐C), lipopolysaccharide, and tumor necrosis factor α (TNFα) activated phosphorylation of IKKϵ and IRF‐3 in FLS. DN IKKϵ inhibited IRF‐3 phosphorylation as well as RANTES and IFNβ protein production in synoviocytes. Antiviral gene expression was also reduced in FLS from IKKϵ^−/− mice compared with IKKϵ^+/+ mice.

Conclusion

Antiviral gene expression in RA, especially due to TLR ligands and TNFα, is dependent on IKKϵ and IRF‐3, and this pathway plays a key role in the production of type I IFNs and chemokines such as RANTES. These findings indicate that the IKKϵ pathway may have potential as a therapeutic target in RA.

     

Role of FK506 binding protein 5 (FKBP5) in osteoclast differentiation

Objectives

We previously disclosed the enhanced expression of FK506 binding protein 5 (FKBP5) messenger RNA (mRNA) in bone marrow (BM) CD34⁺ cells in rheumatoid arthritis (RA), in which systemic osteoporosis takes place. Since BM CD34⁺ cells are precursors of osteoclasts, it is possible that FKBP5 overexpression might lead to osteoporosis by affecting osteoclastogenesis. We therefore explore the influences of FKBP5 in osteoclast differentiation.

Methods

Stable transfectants of RAW264.7 overexpressing murine FKBP5 gene were established. Osteoclast differentiation was induced by receptor activator of nuclear factor kappa B (NF-κB) ligand and was evaluated by tartrate-resistant acid phosphatase (TRAP) staining and pit formation assay.

Results

FKBP5 transfectants of RAW264.7 generated higher numbers of TRAP-positive multinucleated cells with increased activity of pit formation on calcium phosphate-coated culture slides than mock transfectants. The enhancement of osteoclast differentiation of FKBP5 transfectants was only partially inhibited by N-acetyl l-cysteine. Finally, glucocorticoid enhanced FKBP5 mRNA expression as well as osteoclast differentiation of RAW264.7 cells in a dose-dependent manner.

Conclusions

These results indicate that FKBP5 promotes osteoclast differentiation by a mechanism distinct from NF-κB activation. Moreover, the data suggest that FKBP5 might play a role in bone destruction and development of osteoporosis in RA as well as in glucocorticoid-induced osteoporosis.     

Tie2 receptor tyrosine kinase,a major mediator of tumor necrosis factor α–induced angiogenesis in rheumatoid arthritis

Objective

Rheumatoid arthritis (RA) is an inflammatory disease and an angiogenic disease. However, the molecular mechanisms promoting angiogenesis in RA are not clearly identified. Our objective was to study the role of an endothelium‐specific receptor tyrosine kinase, Tie2, in angiogenesis of inflammatory arthritis.

Methods

Expression of Tie2 and its ligand, angiopoietin 1 (Ang1), in human synovium was examined by immunohistochemistry and Western blot. A novel synovium vascular window model was established to study the role of Tie2 in angiogenesis in vivo. Primary cultured endothelial cells and synoviocytes were used to study tumor necrosis factor α (TNFα)–induced Tie2 and Ang1 expression.

Results

Tie2 was implicated in pathologic angiogenesis. We observed that Tie2 and Ang1 were elevated in human RA synovium. Using a novel collagen‐induced arthritis synovial window model, we demonstrated that Tie2 signaling regulated arthritis angiogenesis in vivo. We also showed that Tie2 mediated TNFα‐induced angiogenesis in a mouse cornea assay. In addition, we observed that TNFα can regulate Tie2 activation in multiple ways that may involve interactions between endothelial cells and synoviocytes. TNFα up‐regulates Tie2 in endothelial cells through nuclear factor κB, and it up‐regulates Ang1 in synoviocytes. These findings suggest paracrine regulation of angiogenesis between endothelial cells and synoviocytes.

Conclusion

This study demonstrates that Tie2 regulates angiogenesis in inflammatory synovium. Tie2 signaling is an important angiogenic mediator that links the proinflammatory cytokine TNFα to pathologic angiogenesis.

     

Regenerating gene (REG) 1 alpha promotes pannus progression in patients with rheumatoid arthritis

Introduction

A protein analysis using mass spectrometry revealed the existence of serum proteins with significant quantitative changes after the administration of infliximab. Among these proteins, regenerating gene (REG) 1?? appears to be related to the pathogenesis of rheumatoid arthritis (RA). Therefore, the present study was conducted to examine the mechanism of REG1?? in RA disease progression.

Methods

Serum samples were collected from RA patients and normal healthy controls. REG1?? expression was evaluated by ELISA, RT-PCR, and indirect immunofluorescence microscopy. The functions of REG1?? on synovial fibroblasts with regard to apoptosis, receptor activator of NF-??B ligand (RANKL) expression, and cellar proliferation were evaluated using siRNA to inhibit the intrinsic REG1?? mRNA expression.

Results

The serum concentrations of REG1?? in RA patients were higher than in normal healthy controls. The high expression of REG1?? was also observed in the synovial tissue of RA patients compared to those of osteoarthropathy patients. In addition, tumor necrosis factor-?? (TNF-??) upregulated REG1?? expression in the synovial fibroblasts cell line (MH7A). Inhibition of REG1?? expression suppressed the induction of RANKL expression by TNF-??. Furthermore, exogenous recombinant REG1?? protein inhibited apoptosis and promoted cell proliferation in MH7A cells. These effects were abolished in the REG1??-siRNA MH7A cells.

Conclusion

The present data suggest that TNF-?? induces aberrant REG1?? expression and that REG1?? plays an important role in aberrant cell proliferation and RANKL expression of synovial fibroblasts, ultimately resulting in pannus formation. Restoration of normal physiological REG1?? expression may contribute to disease amelioration.     

Role of placenta growth factor and its receptor flt‐1 in rheumatoid inflammation: A link between angiogenesis and inflammation

Objective

To investigate the direct effects of placenta growth factor (PlGF) and its specific receptor, flt‐1, which are known to mediate angiogenesis, on the inflammatory process of rheumatoid arthritis (RA).

Methods

Expression of PlGF and flt‐1 in the synovial tissue of RA patients was examined using immunohistochemistry. Enzyme‐linked immunosorbent assay was used to determine the concentrations of PlGF, tumor necrosis factor α (TNFα), and interleukin‐6 (IL‐6) in culture supernatants of either mononuclear cells or synoviocytes. The flt‐1 expression level in mononuclear cells was analyzed by flow cytometry. Experimental arthritis was induced in mice either by immunization with type II collagen (CII) or by injection of anti‐CII antibody.

Results

PlGF was highly expressed in the synovium of RA patients, and its primary source was fibroblast‐like synoviocytes (FLS). When stimulated with IL‐1β, FLS from RA patients produced higher amounts of PlGF than did FLS from patients with osteoarthritis. Exogenous PlGF specifically increased the production of TNFα and IL‐6 in mononuclear cells from RA patients (but not those from healthy controls) via a calcineurin‐dependent pathway. The response to PlGF was associated with increased expression of flt‐1 on RA monocytes, which could be induced by IL‐1β and TNFα. A novel anti–flt‐1 hexapeptide, GNQWFI, abrogated the PlGF‐induced increase in TNFα and IL‐6 production, and also suppressed CII‐induced arthritis and serum IL‐6 concentrations in mice. Moreover, genetic ablation of PlGF prevented the development of anti‐CII antibody–induced arthritis in mice.

Conclusion

Our data suggest that enhanced expression of PlGF and flt‐1 may contribute to rheumatoid inflammation by triggering production of proinflammatory cytokines. The use of the novel anti–flt‐1 peptide, GNQWFI, may be an effective strategy for the treatment of RA.

     

CXCL12 secreted from adipose tissue recruits macrophages and induces insulin resistance in mice

Aims/hypothesis

Obesity-induced inflammation is initiated by the recruitment of macrophages into adipose tissue. The recruited macrophages, called adipose tissue macrophages, secrete several proinflammatory cytokines that cause low-grade systemic inflammation and insulin resistance. The aim of this study was to find macrophage-recruiting factors that are thought to provide a crucial connection between obesity and insulin resistance.

Methods

We used chemotaxis assay, reverse phase HPLC and tandem MS analysis to find chemotactic factors from adipocytes. The expression of chemokines and macrophage markers was evaluated by quantitative RT-PCR, immunohistochemistry and FACS analysis.

Results

We report our finding that the chemokine (C-X-C motif) ligand 12 (CXCL12, also known as stromal cell-derived factor 1), identified from 3T3-L1 adipocyte conditioned medium, induces monocyte migration via its receptor chemokine (C-X-C motif) receptor 4 (CXCR4). Diet-induced obese mice demonstrated a robust increase of CXCL12 expression in white adipose tissue (WAT). Treatment of obese mice with a CXCR4 antagonist reduced macrophage accumulation and production of proinflammatory cytokines in WAT, and improved systemic insulin sensitivity.

Conclusions/interpretation

In this study we found that CXCL12 is an adipocyte-derived chemotactic factor that recruits macrophages, and that it is a required factor for the establishment of obesity-induced adipose tissue inflammation and systemic insulin resistance.     

Prognostic relevance of ubiquitin C-terminal hydrolase L1 (UCH-L1) mRNA and protein expression in breast cancer patients

Purpose

The ubiquitin C-terminal hydrolase L1 (UCH-L1) belongs to the family of deubiquitinating enzymes. It is overexpressed in various tumour entities and associated with metastases formation in some solid tumours. However, only limited information about its role in breast cancer is available. The aim of this study was to examine the UCH-L1 expression in primary breast cancer and to determine its relevance as a potential prognostic marker.

Methods

We investigated both UCH-L1 mRNA expression in microarray data from 182 primary mammary carcinomas and UCH-L1 protein expression using a tissue microarray containing samples from 1,622 breast cancer patients.

Results

With both methods, high UCH-L1 expression correlated significantly with negative oestrogen receptor and progesterone receptor status and advanced tumour stage. Moreover by Kaplan–Meier analysis, high UCH-L1 mRNA and protein expression correlated with a significantly shorter overall survival.

Conclusion

The data of our study suggest that high levels of UCH-L1 expression indicate a more aggressive tumour behaviour and might represent a potential target in breast cancer treatment.