Gelatinase activity in synovial fluid and synovium obtained from healthy and osteoarthritic joints of dogs

Genetic dissection of canine hip dysplasia phenotypes and osteoarthritis reveals three novel loci

Background

Hip dysplasia and osteoarthritis continue to be prevalent problems in veterinary and human medicine. Canine hip dysplasia is particularly problematic as it massively affects several large-sized breeds and can cause a severe impairment of the quality of life. In Finland, the complex condition is categorized to five classes from normal to severe dysplasia, but the categorization includes several sub-traits: congruity of the joint, Norberg angle, subluxation degree of the joint, shape and depth of the acetabulum, and osteoarthritis. Hip dysplasia and osteoarthritis have been proposed to have separate genetic etiologies.

Results

Using Fédération Cynologique Internationale -standardized ventrodorsal radiographs, German shepherds were rigorously phenotyped for osteoarthritis, and for joint incongruity by Norberg angle and femoral head center position in relation to dorsal acetabular edge. The affected dogs were categorized into mild, moderate and severe dysplastic phenotypes using official hip scores. Three different genome-wide significant loci were uncovered. The strongest candidate genes for hip joint incongruity were noggin (NOG), a bone and joint developmental gene on chromosome 9, and nanos C2HC-type zinc finger 1 (NANOS1), a regulator of matrix metalloproteinase 14 (MMP14) on chromosome 28. Osteoarthritis mapped to a long intergenic region on chromosome 1, between genes encoding for NADPH oxidase 3 (NOX3), an intriguing candidate for articular cartilage degradation, and AT-rich interactive domain 1B (ARID1B) that has been previously linked to joint laxity.

Conclusions

Our findings highlight the complexity of canine hip dysplasia phenotypes. In particular, the results of this study point to the potential involvement of specific and partially distinct loci and genes or pathways in the development of incongruity, mild dysplasia, moderate-to-severe dysplasia and osteoarthritis of canine hip joints. Further studies should unravel the unique and common mechanisms for the various sub-traits.

MMP-2 as an early synovial biomarker for cranial cruciate ligament disease in dogs

Objectives: To measure the activity of matrix metalloproteinases (MMP)-2 and -9 in synovial fluid from the stifle joints of dogs with cranial cruciate ligament (CrCL) rupture and to compare that to values from contralateral stifle joints and dogs with clinically normal stifle joints. Additionally, the C-reactive protein (CRP) levels were also measured.

Methods: Fourteen large breed dogs with unilateral CrCL rupture and 11 large breed normal dogs were included in this prospective clinical study. Synovial fluid was collected from CrCL-ruptured stifle joints, contralateral clinically normal stifle joints of the same dogs, and stifle joints of normal dogs. Serum was also collected. Synovial fluid activities of MMP-2 and MMP-9 and serum CRP level were measured.

Results: The MMP-2 activity in synovial fluid was significantly higher in CrCL-ruptured joints compared to contralateral joints and to stifles from normal dogs. There was no significant difference in activity of MMP-2 in contralateral joints of CrCL-ruptured dogs compared to normal dogs. Both serum CRP level and MMP-9 activity did not differ significantly between the studied conditions.

Clinical significance: It was confirmed that MMP-2 activity is significantly related to CrCL rupture, but there was a failure to demonstrate any significant increase in the contralateral joints compared to the stifle joints of normal dogs. The MMP-2 involvement in progressing CrCL disease still has to be defined.

Significance of epigenetic landscape in cartilage regeneration from the cartilage development and pathology perspective

Regenerative therapies for cartilage defects have been greatly advanced by progress in both the stem cell biology and tissue engineering fields. Despite notable successes, significant barriers remain including shortage of autologous cell sources and generation of a stable chondrocyte phenotype using progenitor cells. Increasing demands for the treatment of degenerative diseases, such as osteoarthritis and rheumatoid arthritis, highlight the importance of epigenetic remodeling in cartilage regeneration. Epigenetic regulatory mechanisms, such as microRNAs, DNA methylation, and histone modifications, have been intensively studied due to their direct regulatory role on gene expression. However, a thorough understanding of the environmental factors that initiate these epigenetic events may provide greater insight into the prevention of degenerative diseases and improve the efficacy of treatments. In other words, if we could identify a specific factor from the environment and its downstream signaling events, then we could stop or retard degradation and enhance cartilage regeneration. A more operational definition of epigenetic remodeling has recently been proposed by categorizing the signals during the epigenetic process into epigenators, initiators, and maintainers. This review seeks to compile and reorganize the existing literature pertaining to epigenetic remodeling events placing emphasis on perceiving the landscape of epigenetic mechanisms during cartilage regeneration with the new operational definition, especially from the environmental factors' point of view. Progress in understanding epigenetic regulatory mechanisms could benefit cartilage regeneration and engineering on a larger scale and provide more promising therapeutic applications.

Matrix metalloproteinase activity in stifle synovial fluid of cranial cruciate ligament deficient dogs and effect of postoperative doxycycline treatment

This prospective clinical study investigated the activity of matrix metalloproteinases (MMPs) in stifle synovial fluid (SF) of 13 dogs with acute cranial cruciate ligament (CCL) rupture, and the effect of a postoperative doxycycline treatment. MMP-2, 3, 9 and 13 activities were compared with respect to the time of sampling (preoperatively or 1 month after surgical stabilisation) and the type of postoperative adjuvant treatment (doxycycline or not). No significant activity was detected for both MMP-3 and MMP-13. MMP-2 and MMP-9 activities were found to be significantly highly increased in SF of CCL ruptured stifles compared to control stifles of unaffected dogs. No significant effect from surgical stabilisation and postoperative doxycycline treatment on MMP-2 and MMP-9 activities was found, indicating that doxycycline may not be an appropriate postoperative medical treatment after CCL rupture.

Detection and evaluation of matrix metalloproteinases involved in cruciate ligament disease in dogs using multiplex bead technology

OBJECTIVE

To measure matrix metalloproteinases (MMPs) suspected to be involved in the initiation or progression of osteoarthritis (OA) in cranial cruciate ligament (CCL) explant culture media using multiplex bead technology.

STUDY DESIGN

In vitro experimental study.

ANIMALS

Adult dogs with (n=10) and without (n=10) CCL deficiency.

METHODS

Based on clinical, radiographic, and gross evidence of CCL deficiency, excised CCL were classified as normal and intact (n=10) or partially torn (n=10). The ligament was excised and immediately placed in tissue culture. Culture media were sampled and replaced on days 3 and 6. MMP-1, 2, 3, 9, and 13 were quantified in explant media using a multiplexing machine that uses flow cytometry, microspheres, spectral dyes, lasers, digital signal processing, and traditional chemistry. MMP concentrations were determined using a standard curve constructed from the serial dilution of positive controls. Media MMP concentrations comparing the type of ligament and the time frame were analyzed using a Mann-Whitney rank sum test.

RESULTS

Media exposed to intact ligaments had >3 times the amount of MMP-2 than for partially torn ligaments on day 6 (P=.006). Media exposed to intact ligaments also had significantly higher levels of MMP-3 than for partially torn ligaments on day 3 (P=.035) and on day 6 (P=.05).

CONCLUSIONS

MMP multiplexing is a reliable, cost-effective, efficient, and sample-sparing method of MMP quantification. MMP-2, 3, 9, and 13 are released from CCL explants exposed to culture media and can be detected using multiplex bead technology.

CLINICAL RELEVANCE

CCL remnants exposed to the intra-articular environment may release degradative enzymes in vivo similar to that demonstrated in this in vitro study. Because MMPs are known to be involved in the initiation and progression of OA, debridement of these remnants as a component of treatment for cruciate disease in dogs deserves consideration.

Treatment with ephrin B2 positively impacts the abnormal metabolism of human osteoarthritic chondrocytes

Introduction

Members of the ephrin system, the ephrin receptor erythropoietin-producing hepatocellular B4 (EphB4) and its specific ligand, ephrin B2, appear to be involved in the bone remodelling process. We recently showed that their interaction inhibits the resorptive activity of human osteoarthritic (OA) subchondral bone osteoblasts. Hence, we further investigated the possible implication of these ephrin members on the catabolic/anabolic activities of human OA chondrocytes.

Methods

EphB4 receptor and ephrin B2 levels were determined by quantitative PCR and immunohistochemistry, and the effects of ephrin B2 on the expression/production of factors involved in the OA process.

Results

EphB4 receptors and ephrin B2 ligands are expressed and produced by human normal and OA chondrocytes. Ephrin B2 protein was found at similar levels in both cartilage types, whereas EphB4 receptor expression (P < 0.0001) and production (P < 0.01) levels were significantly increased in OA chondrocytes/cartilage. Ephrin B2 treatment significantly inhibited the interleukin (IL)-1beta, IL-6, matrix metalloproteinase-1 (MMP-1), MMP-9, MMP-13, and proteinase-activated receptor-2 (PAR-2) gene expression levels, whereas MMP-2 was unaffected, and significantly increased collagen type II, a cartilage specific macromolecule. It also inhibited the IL-1beta stimulated protein production of IL-6, MMP-1 and MMP-13.

Conclusions

Our study is the first to provide data on the presence and role of ephrin B2/EphB4 receptors in human chondrocytes/cartilage. Data showed that ephrin B2 treatment positively impacts the abnormal metabolism of OA cartilage by inhibiting important catabolic factors involved in this disease at the same time as increasing anabolic activity.

Determination of MMP-2 and -9 activities in synovial fluid of horses with osteoarthritic and arthritic joint diseases using gelatin zymography and immunocapture activity assays

REASON FOR PERFORMING STUDY

Matrix metalloproteinases (MMPs)-2 and -9 activities have been found elevated in synovial fluid from various joint diseases in man. However, in the horse few data are available.

OBJECTIVES

To explore the clinical significance of MMP-2 and -9 activities in synovial fluid of horses with different forms of joint diseases.

METHODS

Gelatin zymography and MMP-2 and -9 immunocapture activity assays were applied on synovial fluids from control joints and joints with aseptic joint disease (AJD) and septic arthritis (SA). Additionally, MMP-2 and -9 activities were measured in samples from SA to monitor the disease process.

RESULTS

Zymographic analysis revealed that samples from AJD and SA contained significantly increased latent MMP-2 activity compared to controls. Samples from SA showed significantly increased monomeric latent MMP-9 activity compared with all other affected joints and controls. Trace amounts of MMP-9 activity, due to the active and dimer form, were detected in samples from SA; however, these bands were absent in samples from AJD and controls. Using immunocapture activity assays, MMP-2 and -9 activities were found to be significantly elevated in joints from SA compared to controls and AJD samples. MMP-2 activity in samples from AJD was significantly increased compared to controls. Both MMP activities decreased in the joints from SA in the course of successful therapy.

CONCLUSIONS

Data from zymographic analysis confirmed that MMP-2 and -9 were elevated in equine joint diseases. Immunocapture activity assays have been shown to be suitable for the quantitative determination of MMP-2 and -9 activities in synovial fluid of horses. Both MMP-2 and -9 activities seem to be useful to indicate SA, and MMP-2 activity might be a suitable marker for AJD.

POTENTIAL RELEVANCE

These findings encourage the potential use of MMP-2 and -9 as additional aids to clinical investigation. Further work is required to validate the clinical significance of MMP activities in the progress of different joint diseases in horses.

Fish oil decreases matrix metalloproteinases in knee synovia of dogs with inflammatory joint disease

This study was designed to determine whether dietary fish oil affects the expression and activity of matrix metalloproteinases (MMP), tissue inhibitors of MMP-2 (TIMP-2) and urokinase plasminogen activator (uPA) in synovial fluid from dogs with spontaneously occurring stifle (knee) instability in a single hind limb resulting from acute cranial cruciate ligament (CCL) injury. Two groups of 12 dogs were fed diets from 1 week prior to surgery on the affected knee to 56 days post-surgery. The fish oil and control diets provided 90 and 4.5 mg, respectively, of combined eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)/kg body weight per day. Plasma and synovial fluid, from both surgical and nonsurgical knee joints, were obtained at start of the diet (-7), surgery day (0) and 7, 14, 28 and 56 days post-surgery. Plasma total EPA and DHA were significantly increased, and plasma total arachidonic acid (AA) was significantly decreased by the fish oil diet. In synovial fluid from the nonsurgical knee, fish oil treatment significantly decreased proMMP-2 expression at Days 7 and 14, and proMMP-9 expression at Day 56, and uPA activity at 28 days and significantly increased TIMP-2 expression at Days 7 and 28. There were no differences in MMP expression or activity, TIMP-2 expression and uPA activity in the surgical joint synovial fluid at any time throughout the study. These results suggest that dietary fish oil may exert beneficial effects on synovial fluid MMP and TIMP-2 equilibrium in the uninjured stifle of dogs with unilateral CCL injury.

Expression of immune response genes in the stifle joint of dogs with oligoarthritis and degenerative cranial cruciate ligament rupture

Dysregulation of immune responses within joints plays an important role in development of inflammatory arthritis. We determined expression of a panel of immune response and matrix turnover genes in synovial fluid collected from a group of dogs with stifle oligoarthritis and associated degenerative cranial cruciate ligament (CCL) rupture (n=27). We also studied synovial fluid gene expression in dogs affected with other forms of degenerative arthritis (n=9) and in the stifle joint of healthy dogs with intact CCL (n=14). After collection, synovial cells were pelleted and RNA was isolated. Relative expression of cathepsin K, cathepsin S, tartrate-resistant acid phosphatase (TRAP), matrix metalloproteinase-9 (MMP-9), invariant chain (li), toll-like receptor-2 (TLR-2), and TLR-9 was determined using real-time quantitative RT-PCR. Data were normalized to peripheral blood mononuclear cells (PBMC) as an internal control. Relative expression of cathepsin K, MMP-9, TRAP, and li was increased in the stifle synovial fluid of dogs with oligoarthritis, when compared with the stifles of healthy dogs (P<0.05). In contrast, relative expression of all of the genes-of-interest in synovial fluid from joints affected with other forms of arthritis was not significantly different from the stifles of healthy dogs. TRAP expression was also significantly increased in the stifle joints of dogs with oligoarthritis, when compared to joint expression of TRAP in dogs with other forms of degenerative arthritis (P<0.05). In the dogs with stifle oligoarthritis, expression of both matrix turnover and immune response genes was increased in stifle synovial fluid, when compared with the internal PBMC control, whereas in healthy dogs and dogs with other forms of arthritis, only expression of matrix turnover genes was increased in synovial fluid, when compared with the internal PBMC control (P<0.05). Taken together, these findings suggest that antigen-specific immune responses within the stifle joint may be involved in the pathogenesis of persistent synovitis and associated joint degradation in dogs with oligoarthritis and degenerative CCL rupture.

Effects of treatment with polysulfated glycosaminoglycan on serum cartilage oligomeric matrix protein and C-reactive protein concentrations, serum matrix metalloproteinase-2 and -9 activities, and lameness in dogs with osteoarthritis

OBJECTIVE

To investigate the effects of polysulfated glycosaminoglycan (PSGAG) treatment on serum cartilage oligomeric matrix protein (COMP) concentration, matrix metal-loproteinase-2 (MMP-2) and -9 (MMP-9) activities, C-reactive protein (CRP) concentration, and lameness scores in dogs with osteoarthritis.

ANIMALS

16 dogs with osteoarthritis and 5 clinically normal dogs.

PROCEDURES

Dogs with osteoarthritis had a history of chronic lameness, and osteophytes were observed on radiographic evaluation of the affected joint. Polysulfated glycosaminoglycan was administered IM twice a week for a total of 8 treatments to all dogs with osteoarthritis and to clinically normal control dogs.

RESULTS

Lameness scores after PSGAG treatment in osteoarthritic dogs improved in 12 of the 16 dogs. Serum COMP concentrations in osteoarthritic dogs were significantly higher than in control dogs before treatment. Lameness scores in osteoarthritic dogs decreased significantly after treatment, compared with before treatment. Lameness scores of 9 dogs with hind limb lameness improved significantly after treatment; these dogs had corresponding decreases in serum COMP concentrations. After treatment, serum COMP concentrations and lameness scores of 7 dogs with forelimb lameness remained high and were significantly higher than those of dogs with hind limb lameness. Serum MMP-9 activities of dogs with forelimb lameness were significantly higher than in dogs with hind limb lameness after treatment.

CONCLUSIONS AND CLINICAL RELEVANCE

IM administration of PSGAG inhibited COMP degradation in dogs with osteoarthritis. Results indicate that decreases in serum COMP concentrations might be related to improvement in lameness after PSGAG treatment.

Expression profiling of metalloproteinases and their inhibitors in synovium and cartilage

Cartilage destruction in osteoarthritis (OA) is thought to be mediated by two main enzyme families; the matrix metalloproteinases (MMPs) are responsible for cartilage collagen breakdown, whereas enzymes from the 'a disintegrin and metalloproteinase domain with thrombospondin motifs' (ADAMTS) family mediate cartilage aggrecan loss. Tissue inhibitors of metalloproteinases (TIMPs) regulate the activity of these enzymes. Although cartilage destruction in OA might be driven by the chondrocyte, low-grade synovitis is reported in patients with all grades of this disease.

Our earlier work profiling these gene families in cartilage identified a number of genes that are regulated in OA, which are hence implicated in the disease process. Because the synovium might contribute to cartilage-matrix destruction in OA, we have extended the screening in the current study. We have profiled MMP, ADAMTS and TIMP genes in both cartilage and synovium from patients with either OA of the hip or a fracture to the neck of femur (NOF), giving a more complete picture of proteolysis in this disease.

The four most significantly upregulated genes (P < 0.0001) in OA synovium compared to the fractured NOF are MMP28, ADAMTS16, ADAMTS17 and TIMP2. For MMP9, MMP10, MMP12, MMP17, MMP23, MMP28, ADAMTS4, and ADAMTS9, there is a significant correlation between expression levels in the synovium and cartilage, suggesting similar mechanisms of regulation. Additionally, we have shown that in cartilage the median level of steady-state mRNA for MMP13 is approximately 20-fold higher than MMP28 and approximately 1,500-fold higher than ADAMTS16, with expression of this latter gene approximately 150-fold higher in synovium than cartilage.

This study is the most comprehensive analysis of the metzincin family of proteinases in the joint to date and has identified several proteinase genes not previously reported to be expressed or regulated in synovium.

Recruited leukocytes and local synthesis account for increased matrix metalloproteinase-9 activity in cerebrospinal fluid of dogs with central nervous system neoplasm

Matrix metalloproteinases (MMP) 2 and 9 are enzymes known to degrade several protein components of the extracellular matrix. In humans, increased concentrations of these enzymes have been demonstrated in the cerebrospinal fluid (CSF) of subjects affected by many neurological conditions including brain tumours; nevertheless comparative data in dogs are completely lacking. Aim of this study was to investigate these molecules in CSF of dogs diagnosed with CNS neurological diseases. Higher activity of MMP 2 and 9 was revealed in dogs with space occupying lesions of likely neoplastic origin in comparison to dogs with idiopathic epilepsy. Statistical modelling reveals that increased MMP 9 activity is mainly due to leukocytes recruitment and local synthesis.

Collagen fragmentation in ruptured canine cranial cruciate ligament explants

Collagen fragmentation in cranial cruciate ligament (CCL) explants and stifle synovial fluid was investigated in dogs with ruptured and intact CCL. Cathepsin K and tartrate-resistant acid phosphatase (TRAP) activities were determined in CCL explant supernatants. Formation of collagen fragments was determined in explant supernatants and stifle synovial fluid. Cathepsin K(+) and TRAP(+) cells were stained specifically in histological sections of CCL. Formation of telopeptide collagen fragments was increased in ruptured CCL explants and stifle synovial fluid from dogs with ruptured CCL. In ruptured CCL explants, release of collagen fragments was associated with extracellular release of TRAP and the presence of cathepsin K(+) cells within CCL tissue. Cathepsin K(+) and TRAP(+) cells were only seen in ruptured CCL. It was concluded that infiltration of the CCL with TRAP(+) cells in dogs with CCL rupture is associated with increased collagenolysis. It is hypothesized that recruitment and activation of TRAP(+) mononuclear cells within the synovium and CCL precipitates CCL rupture through upregulation of collagenolytic enzymes and collagen degradation.

Intra-articular enzyme administration for joint disease in feline mucopolysaccharidosis VI: enzyme dose and interval

Degenerative joint changes have been reported in human mucopolysaccharidosis VI (MPS VI) and are a prominent feature of feline MPS VI. Joint disease has proven refractory to intravenous enzyme replacement therapy (ERT) in the MPS VI cat because enzyme is unable to reach cells in cartilage. In this study, enzyme was infused directly into the intraarticular space to determine whether joint tissues are able to respond to replacement enzyme. Clearance of glycosaminoglycans from chondrocytes was observed at a dose of 10 microg recombinant human N-acetylgalactosamine-4-sulfatase (rh4S), but greater clearance was observed with higher doses. The chondrocytes at the articular surface were cleared preferentially. Lysosomal vacuolation in cruciate ligament and synovial cells also decreased upon addition of rh4S. One month after injection of rh4S, a slight reaccumulation of storage was observed at the surface of the joint, but extensive reaccumulation was observed 2 mo after injection. These results indicate that by bypassing the synovium using intraarticular ERT, significant reduction in storage material in joint tissues can be achieved. Localized ERT in the joint space provides a mechanism for delivering enzyme directly to the articular cartilage and a potential therapy for joint pathology in MPS VI.

Collagenolytic protease expression in cranial cruciate ligament and stifle synovial fluid in dogs with cranial cruciate ligament rupture

OBJECTIVE

To determine expression of collagenolytic genes and collagen degradation in stifle tissues of dogs with ruptured cranial cruciate ligament (CCL).

ANIMALS

Six dogs with CCL rupture and 11 dogs with intact CCL.

PROCEDURES

Gene expression in CCL tissue and synovial fluid cells was studied using reverse transcriptase-polymerase chain reaction (RT-PCR). Collagen degradation was studied using CCL explant cultures and a synovial fluid bioassay.

RESULTS

Expression of matrix metalloproteases (MMP) was not found in young Beagles with intact CCL; however, increased expression of MMP-3 was found in CCL tissue from older hounds with intact CCL, when compared with young Beagles. In dogs with ruptured CCL, expression of MMP-2 and -9 was increased in stifle tissues, when compared with dogs with intact CCL. Similar to MMP-9, expression of tartrate-resistant acid phosphatase (TRAP) and cathepsin S was only found in stifle tissues from dogs with ruptured CCL; in contrast, expression of cathepsin K was found in all ruptured and intact CCL. Collagen degradation was increased in ruptured CCL, when compared with intact CCL.

CONCLUSION

Rupture of the CCL is associated with up-regulation of expression of MMP-2 and -9 (gelatinase A and B), TRAP, and cathepsin S, and increased degradation of collagen.

CLINICAL RELEVANCE

These findings suggest that MMP-2, -9, cathepsin S, and TRAP may be important mediators of progressive joint destruction in dogs with CCL rupture. These genes are markers for macrophages and dendritic cells. MMP and cathepsin S pathways may offer novel targets for anti-inflammatory medical therapy aimed at ameliorating joint degradation associated with inflammatory arthritis.

Interpreting Gelatinase Activity in Tumor Tissue and Serum as a Prognostic Marker of Naturally Developing Canine Tumors

To evaluate the clinical usefulness of tissue and serum gelatinase activity as a prognostic marker of canine tumors, tissue samples from 60 tumors and corresponding serum samples from the same animals were collected at the time of biopsy and surgery. On the basis of histopathology and clinical aggressiveness of metastasis and recurrence (MR), the cases were divided into 6 categories: non-inflammatory (Inf(-)) and inflammatory (Inf(+)) benign, and the Inf(-) MR(-), Inf(-) MR(+), Inf(+) MR(-), and Inf(+) MR(+) malignant. Gelatinase activity was determined semi-quantitatively using gelatin zymogram with a gelatinase standard from cultured canine peripheral blood mononuclear cells stimulated with lipopolysaccharide. No significant difference in gelatinase activities in tissue extracts was evident between the benign and malignant tumors. Inf(+) benign tumors, as well as Inf(-) MR(+), Inf(+) MR(-) and Inf(+) MR(+) malignant tumors, showed significantly higher tissue gelatinase activity than Inf(-) benign. The tissue activity in Inf(-) MR(-) malignant was significantly lower than in Inf(+) MR(-) and Inf(+) MR(+) malignant. The serum activity was significantly higher in the malignant cases than in the control and the benign. Inf(-) MR(+), Inf(+) MR(-) and Inf(+) MR(+) malignant tumors induced significantly higher gelatinase activity in serum than Inf(-) benign tumors. Gelatinase activity in serum was positively correlated with that in tumor extracts. Increased gelatinase in tumor tissue and serum may be correlated with inflammation as well as tumor aggressiveness, and thus should be used in combination with histopathology for predicting tumor metastasis or recurrence.