A tetranectin-related protein is produced and deposited in extracellular matrix by human embryonal fibroblasts

Insight into the function of tetranectin in human diseases: A review and prospects for tetranectin-targeted disease treatment

Tetranectin (TN), a serum protein, is closely associated with different types of cancers. TN binds plasminogen and promotes the proteolytic activation of plasminogen into plasmin, which suggests that TN is involved in remodeling the extracellular matrix and cancer tissues during cancer development. TN is also associated with other diseases, such as developmental disorders, cardiovascular diseases, neurological diseases, inflammation, and diabetes. Although the functional mechanism of TN in diseases is not fully elucidated, TN binds different proteins, such as structural protein, a growth factor, and a transcription regulator. Moreover, TN changes and regulates protein functions, indicating that TN-binding proteins mediate the association between TN and diseases. This review summarizes the current knowledge of TN-associated diseases and TN functions with TN-binding proteins in different diseases. In addition, potential TN-targeted disease treatment by inhibiting the interaction between TN and its binding proteins is discussed.

Comparative analysis of serum proteomes: Identification of proteins associated with sciatica due to lumbar intervertebral disc herniation

Lumbar intervertebral disc herniation (LDH) is one of the most common orthopedic conditions that can cause lower back pain and sciatica. However, the pathogenesis of LDH is poorly understood. The aim of the present study was to use proteomic analysis of blood samples to establish whether there are serum proteins associated with LDH, which may be useful in elucidating LDH pathogenesis. The ultimate aim was to develop a simple technique for the diagnosis of LDH based on the blood samples of patients with sciatica. The study used comparative analysis of serum proteomes associated with sciatica due to LDH. A total of 30 LDH patients with sciatica, receiving treatment between August and December 2007, were selected as the experimental group (or LDH group). A total of 2 ml of blood was obtained from each of the 30 patients in the LDH group and from 30 healthy volunteers, who constituted the control group. Two-dimensional electrophoresis of the blood samples was conducted, distinct protein spots were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and proteins associated with LDH were detected. An enzyme-linked immunosorbent assay (ELISA) was developed to screen for the LDH proteins and was tested on the sera of a second test and control group that included 10 patients with LDH and 10 healthy subjects, respectively. Based on signal intensity, the expression levels of 6 proteins on the dielectrophoretogram were found to be significantly associated with LDH. The identities of the LDH proteins were upregulated apolipoprotein-L1 (APO-L1) and two types of serum albumin precursors, and downregulated apolipoprotein M (APO-M), tetranectin (TN) and immunoglobulin light chain (IGL). Further ELISA experiments confirmed that there were increased serum levels of 4 out of the 6 proteins in patients with sciatica due to LDH, which was statistically different compared to the healthy subjects. In conclusion, these results suggest that serum APO-L1, TN, APO-M and IGL may serve as LDH biomarkers.

Serum tetranectin as a preoperative indicator for postoperative complications in Danish ovarian cancer patients

OBJECTIVE

The association between tetranectin (TN) and selected lifestyle factors (smoking and alcohol) and the postoperative complication rate for ovarian cancer (OC) patients undergoing primary cytoreductive surgery has not yet been characterized. The aim of the study was to examine the value of TN, smoking and alcohol as indicators of postoperative complications in OC patients.

METHODS

Serum TN was measured for 374 OC patients undergoing primary cytoreductive surgery. In addition, they reported their smoking and alcohol status. The prognostic value of variables was found with univariate and multivariate analyses using logistic regression analysis.

RESULTS

In univariate analysis TN was the only one out of 8 variables that significantly predicted postoperative complications (OR=0.55 (95% CI: 0.34-0.87), P=0.01). High preoperative serum TN was associated with a low risk of postoperative complications. Stepwise reduction of the multivariate model demonstrated that TN and histology were the only significant co-variables (TN, OR=0.51 (95% CI: 0.32-0.83), P=0.006; histology, OR=1.70 (95% CI: 1.02-2.82), P=0.041). TN was the only indicator, which was statistical significant in both univariate and multivariate analyses.

CONCLUSION

Preoperative serum TN is a significant indicator of postoperative complications in Danish OC patients and deserves to be validated in larger future studies.

Serum tetranectin is a significant prognostic marker in ovarian cancer patients

OBJECTIVE

To evaluate the prognostic value of preoperative serum tetranectin (TN) in Danish ovarian cancer (OvCa) patients. Design. Population-based, multidisciplinary Danish case-control study of OvCa.

PARTICIPANTS

A total of 445 primary OvCa patients diagnosed at one of the gynecological departments in 18 regional hospitals around Denmark during the period 1994-1999.

METHODS

Serum levels of TN were evaluated preoperatively and tested for possible association with prognosis.

MAIN OUTCOME MEASURES

Disease specific survival.

RESULTS

During the observation period (median 45.9 months, range 0.2-121) 278 OvCa-related deaths were seen. Univariate analysis of TN and CA125 demonstrated a significant association with survival using the Cox proportional hazards model, when stratified for adjuvant treatment (TN: p < 0.0001, hazard ratio = 0.44; 95% confidence interval 0.33-0.60 and CA125: p < 0.0001, hazard ratio = 1.19; 95% confidence interval 1.11-1.27). Disease specific survival curves for patients with tumors in the early stages showed no significant association with survival, neither for TN (p = 0.68) nor for CA125 (p = 0.07). For the stage III group, a significant association with survival was found for TN (p = 0.027), but not for CA125 (p = 0.37). Multivariate Cox analysis identified TN, age, residual tumor, International Federation of Gynecology and Obstetrics stage and grade but not serum CA125 as independent prognostic variables.

CONCLUSION

Preoperative serum TN is a useful prognostic indicator of advanced stage for patients with OvCa.

Tetranectin in cerebrospinal fluid of patients with multiple sclerosis

OBJECTIVE

Tetranectin (TN) is a glycoprotein and C-type lectin thought to play a prominent role in tissue remodelling. The aim of this study was to determine the TN serum and cerebrospinal fluid (CSF) concentration in patients with multiple sclerosis (MS) and controls.

MATERIAL AND METHODS

Two-hundred-and-four patients, divided into four diagnostic groups, i.e. definite MS (n = 76), possible onset symptoms of MS (n = 48), other non-inflammatory neurological diseases (n = 61) and other inflammatory neurological diseases (n = 19) and 47 controls with no history of neurological disease were analysed for TN in serum and CSF using a polyclonal sandwich ELISA.

RESULTS

All tested groups, e.g. definite MS, possible onset symptoms of MS, other neurological disease, both inflammatory and non-inflammatory, had decreased concentrations of TN in the CSF compared to the concentrations in controls. The quotient of TN in CSF divided by the concentration in serum (QTN) correlated significantly with the same quotient of albumin (QALB), was significantly correlated with the same quotient of albumin QALB. To account for differences in blood brain barrier permeability, we calculated a TN-index defined as: TN-index = QTN/QALB. QTN was significantly decreased in all groups compared to that in controls. However, in definite MS and patients with first attack of MS, the TN-index was not significantly different from that of controls. In contrast, other neurological diseases, both inflammatory and non-inflammatory, were associated with a decreased TN-index.

CONCLUSION

These results indicate that TN may play a role in neurological diseases and may serve as a diagnostic aid in MS.

Preoperative serum tetranectin, CA125 and menopausal status used as single markers in screening and in a risk assessment index (RAI) in discriminating between benign and malignant ovarian tumors

OBJECTIVES

To improve the poor survival in ovarian cancer (OC) patients, the research has been focused on new OC markers. One aim is to find markers to identify the cancers in early preclinical stages by screening. Another aim is to find new diagnostic markers, which may select patients at high risk for OC for quick referral to highly specialized centers in gynecologic oncology. These aims were addressed in the present study by evaluating serum tetranectin (TN) and serum CA125 on a large number of pre- and postmenopausal women with ovarian tumors and controls.

METHODS

The potential ability of the markers to discriminate between the four groups (208 benign ovarian tumor, 153 borderline ovarian tumor (BOT), 445 OC and 1333 age matched controls) in OC screening was examined. We also constructed a risk assessment index (RAI) for discrimination between tumor groups based on these variables and menopausal status.

RESULTS

Highly significant differences in both TN and CA125 levels were found between all the four groups as well as between the different FIGO stages of OC patients. A very high probability of having OC or a benign tumor, respectively, was predicted by the RAI.

CONCLUSIONS

In the case-control part of the study, we found that TN and CA125 deserve to be validated on pre-clinical samples by inclusion in future marker panels. The RAI is also a potential new candidate for a diagnostic tool for selecting patients at high risk for having OC; hence it deserves further evaluation in a prospective clinical study.

Expression and prognostic significance of Tetranectin in invasive and non-invasive bladder cancer

Tetranectin (TN) is a plasminogen kringle-4 binding protein that can be detected in the plasma and the extracellular matrix. In malignancies, TN is thought to enhance proteolytic processes enabling tumor cells to invade and metastasize. So far, TN expression has not been described in transitional cell bladder cancer (TCC), and there is no information on the prognostic significance of its in situ expression. TN expression was studied in 99 TCC patients diagnosed between 1994 and 1997. Immunohistochemistry was performed on a tissue microarray using a monoclonal antibody against TN (clone 11F1). Within the mean follow-up period of 60 months, pTa and pT2-4 TCC patients with stainable TN in the tumor stroma had a significant shorter recurrence-free survival and higher risk of recurrence compared to those without stainable TN (p = 0.0002 for both). TN expression in the tumor cells did not influence recurrence-free survival. In conclusion, TN is expressed in a subgroup of bladder cancer patients with a higher risk of recurrence who may take benefit from a closer follow-up.

Oxidative stress and adhesion molecules in children with type 1 diabetes mellitus: a possible link

OBJECTIVE

To examine whether oxidative stress parameters were correlated with adhesion molecules derived from endothelial/platelet activation in a group of juveniles with type 1 diabetes mellitus (T1DM).

SUBJECTS AND METHODS

Indicative parameters of patient oxidant/antioxidant capacity were measured and associated with P-selectin and tetranectin (TN), markers of endothelial/platelet activation, in the plasma of 45 diabetic children and adolescents and 20 healthy age-matched subjects (HS).

RESULTS

Significantly, higher nitrate/nitrite (NOx) and lipid hydroperoxide (LPO) levels (p=0.049 and p=0.0011, respectively), lower glutathione peroxidase activity (GPx; p=0.038), and elevated TN and P-selectin plasma levels (p=0.0046 and p=0.042, respectively) were found in T1DM children compared with HS. Well-controlled T1DM children (HbA1c <or= 7%) showed significantly lower GPx (p=0.0259), higher NOx and LPO (p=0.01093 and p=0.0092, respectively) compared with HS, while poorly controlled patients (HbA1c >7%) showed significantly higher TN, sP-selectin and LPO (p=0.0064, p=0.0234 and p=0.0121, respectively), a tendency to higher NOx (p=0.063) compared with HS and only TN higher (p=0.0123) compared with well-controlled patients. Patients with shorter diabetes duration (<or=3 yr) showed significantly higher LPO and TN (p=0.034 and 0.017, respectively), a tendency to higher NOx and lower GPx and higher P-selectin, while those with longer duration (>3 yr) differed significantly in all the examined parameters (TN, p=0.0015; GPx, p=0.0420; NOx, p=0.0196; LPO, p=0.0054; sP-selectin, p=0.0187) compared with HS.

CONCLUSIONS

Decreased antioxidative protection from simultaneous LPO and NOx overproduction is evident in T1DM juveniles with a parallel endothelial/platelet activation even in the first years of the disease, being more pronounced later in diabetes progression, contributing to the vascular complications of the disease.

Tetranectin in cerebrospinal fluid: Biochemical characterisation and evidence of intrathecal synthesis or selective uptake into CSF

BACKGROUND

Tetranectin (TN) is a 67 kDa glycoprotein thought to play a prominent role in the regulation of proteolytic processes via its binding to plasminogen and indirect activation of plasminogen. The TN concentration in serum is approximately 10 mg/l and is reduced in patients with several cancers. The TN concentration in the normal CSF has not been examined.

METHODS

The TN concentration in the serum and CSF of 47 normal subjects without neurological disorders was established using a polyclonal sandwich ELISA.

RESULTS

The median TN concentration (quartile range) was 10.8 mg/l (9.0-12.1) in serum and 0.43 mg/l (0.3-0.53) in CSF. The TN index median (quartile range), defined as (TN CSF concentration/TN serum concentration)/(Albumin CSF concentration/Albumin serum concentration), was found to be 5.5 (4.7-7.6), suggesting intrathecal synthesis or selective uptake of TN in CNS. Immunohistochemistry showed TN immunoreactivity in neurons and dendrites, but no staining in glial cells in the cerebrum and cerebellum. In plexus choroideus, the ependymal cells exhibited strong immunoreactivity. TN in serum and CSF were immunochemically identical and of similar size.

CONCLUSION

TN is present in normal brain and CSF, and the TN index is very high, but further studies are necessary to decide whether TN is synthesised in the CNS or selectively transported over the blood-brain barrier.

Aberrant tetranectin expression in human breast carcinomas as a predictor of survival

AIMS

Tetranectin (TN), a plasminogen kringle 4 binding protein, is thought to play a prominent role in the regulation of proteolytic processes via binding to plasminogen. The aim of this study was to evaluate the expression of TN in human breast cancer and adjacent normal breast tissue and to determine the impact of this expression on survival.

METHODS

A retrospective analysis was performed on 189 patients with breast cancer, with a median follow up time of 10.6 years. The expression of TN was assessed in tumour tissue and adjacent normal breast tissue by immunohistochemistry, and the prognostic relevance of its expression in tumour cells was evaluated.

RESULTS

TN was highly expressed in connective tissue fibres surrounding normal breast epithelium, but not in normal epithelial cells. High expression of TN in tumour cells was found in 131 (69%) of the tumour samples. By western blot analysis, no significant difference in the amount and molecular weight of TN was seen between tumour tissue and normal tissue. Strong TN immunoreactivity in tumour tissue was predictive of poor disease free and tumour specific overall survival. By multivariate analysis, high TN expression in cancer cells was an independent prognostic factor for disease free and tumour specific overall survival.

CONCLUSIONS

Our results demonstrate differential TN expression in normal and malignant breast tissue and a prognostic impact of TN protein expression in breast carcinoma tissue. These data suggest a possible role of TN in invasiveness and the metastatic spread of human breast cancer.

Tetranectin Binds to the Kringle 1-4 Form of Angiostatin and Modifies Its Functional Activity

Tetranectin is a plasminogen kringle 4 domain-binding protein present in plasma and various tissue locations. Decreased plasma tetranectin or increased tetranectin in stroma of cancers correlates with cancer progression and adverse prognosis. A possible mechanism through which tetranectin could influence cancer progression is by altering activities of plasminogen or the plasminogen fragment, angiostatin. Tetranectin was found to bind to the kringle 1-4 form of angiostatin (AST $;{\text{K1-4}}$ ). In addition, tetranectin inhibited binding of plasminogen or AST $;{\text{K1-4}}$ to extracellular matrix (ECM) deposited by endothelial cells. Finally, tetranectin partially counteracted the ability of AST $;{\text{K1-4}}$ to inhibit proliferation of endothelial cells. This latter effect of tetranectin was specific for AST $;{\text{K1-4}}$ since it did not counteract the antiproliferative activities of the kringle 1-3 form of angiostatin (AST $;{\text{K1-3}}$ ) or endostatin. These findings suggest that tetranectin may modulate angiogenesis through interactions with AST.

The plasminogen binding site of the C-type lectin tetranectin is located in the carbohydrate recognition domain, and binding is sensitive to both calcium and lysine

Tetranectin, a homotrimeric protein belonging to the family of C-type lectins and structurally highly related to corresponding regions of the mannose-binding proteins, is known specifically to bind the plasminogen kringle 4 protein domain, an interaction sensitive to lysine. Surface plasmon resonance and isothermal calorimetry binding analyses using single-residue and deletion mutant tetranectin derivatives produced in Escherichia coli showed that the kringle 4 binding site resides in the carbohydrate recognition domain and includes residues of the putative carbohydrate binding site. Furthermore, the binding analysis revealed that the interaction is sensitive to calcium in addition to lysine.

Crystal structure of tetranectin, a trimeric plasminogen-binding protein with an alpha-helical coiled coil

Tetranectin is a plasminogen kringle 4-binding protein. The crystal structure has been determined at 2.8 A resolution using molecular replacement. Human tetranectin is a homotrimer forming a triple alpha-helical coiled coil. Each monomer consists of a carbohydrate recognition domain (CRD) connected to a long alpha-helix. Tetranectin has been classified in a distinct group of the C-type lectin superfamily but has structural similarity to the proteins in the group of collectins. Tetranectin has three intramolecular disulfide bridges. Two of these are conserved in the C-type lectin superfamily, whereas the third is present only in long-form CRDs. Tetranectin represents the first structure of a long-form CRD with intact calcium-binding sites. In tetranectin, the third disulfide bridge tethers the CRD to the long helix in the coiled coil. The trimerization of tetranectin as well as the fixation of the CRDs relative to the helices in the coiled coil indicate a demand for high specificity in the recognition and binding of ligands.

The urokinase-type plasminogen activator system in cancer metastasis: a review

The urokinase-type plasminogen activator (u-PA) system consists of the serine proteinases plasmin and u-PA; the serpin inhibitors alpha2-anti-plasmin, PAI-1 and PAI-2; and the u-PA receptor (u-PAR). Two lines of evidence have strongly suggested an important and apparently causal role for the u-PA system in cancer metastasis: results from experimental model systems with animal tumor metastasis and the finding that high levels of u-PA, PAI-1 and u-PAR in many tumor types predict poor patient prognosis. We discuss here recent observations related to the molecular and cellular mechanisms underlying this role of the u-PA system. Many findings suggest that the system does not support tumor metastasis by the unrestricted enzyme activity of u-PA and plasmin. Rather, pericellular molecular and functional interactions between u-PA, u-PAR, PAI-1, extracellular matrix proteins, integrins, endocytosis receptors and growth factors appear to allow temporal and spatial re-organizations of the system during cell migration and a selective degradation of extracellular matrix proteins during invasion. Differential expression of components of the system by cancer and non-cancer cells, regulated by paracrine mechanisms, appear to determine the involvement of the system in cancer cell-directed tissue remodeling. A detailed knowledge of these processes is necessary for utilization of the therapeutic potential of interfering with the action of the system in cancers.

The plasminogen activation system in tumour invasion and metastasis

The involvement of proteases in the metastatic spread of tumour cells and in tumour related processes, such as angiogenesis and ulceration, has been known for many decades. This chapter reviews the involvement of one proteolytic system--the plasminogen activation system--in tumour progression. In recent years, many biochemical properties of the various components of the plasminogen activation system have become known. These properties and the functional relationship between the components are discussed in the first section. Since interfering with proteolysis by tumour cells and by newly formed endothelial cells can be an objective for future therapy, experimental tumour models have been used to study the effects of inhibitors of plasminogen activation. The second section deals with this issue. Finally, the presence of the various components of the plasminogen activation system in human tumours is reviewed. Following the availability of specific ELISAs, antibodies and molecular probes, the content and the cellular distribution of the components of the plasminogen activation system have recently been mapped in various human tumours.

Tetranectin and plasmin/plasminogen are similarly distributed at the invasive front of cutaneous melanoma lesions

The induction of expression of the components of the proteolytic plasminogen activation system in cutaneous melanocytic tumour progression has previously been reported. Plasminogen activators, their inhibitors, and the receptor for urokinase were present only in advanced primary melanomas and melanoma metastases. The present study reports on the presence of tetranectin and plasmin/ plasminogen, two proteins connected with plasminogen activation, in cutaneous melanocytic lesions. The distribution of tetranectin and plasminogen was studied by immunohistochemistry in 105 freshly frozen melanocytic lesions of common naevocellular naevi (n = 24), atypical naevi (n = 14), early (n = 12) and advanced (n = 20) primary melanomas, and melanoma metastases (n = 35). Both tetranectin and plasminogen were detected in a variety of tissue components. In all stages of melanocytic tumour progression, tetranectin was found in endothelium, perivascular dendritic cells, and leukocytes. Plasminogen was present in endothelium and in the basal layer of the normal skin. Tetranectin and plasminogen staining of fibroblastic cells at the invasive front and of extracellular matrix was, however, restricted to malignant lesions. Co-localization of tetranectin and plasminogen was found in 50 per cent of the early primary melanomas and in more than 75 per cent of the advanced melanomas and melanoma metastases. These results suggest a coordinated role for tetranectin and plasminogen at the invasive front of melanomas. Tetranectin-bound plasminogen may facilitate the migration of tumour cells.

Plasma tetranectin and colorectal cancer

The prognostic significance of plasma tetranectin (PL-TN) in colorectal cancer was retrospectively examined in 504 patients (80 Dukes' A, 174 Dukes' B, 98 Dukes' C and 152 Dukes' D). Follow-up time was 7-12 years. No significant prognostic variable was found for Dukes' A patients by Cox multivariate analysis. In stage B, PL-TN was the second strongest prognostic variable [relative hazard (RH) = 3.3 for patients with PL-TN < or = 7.5 mg/l]. The other prognostic variables were perineural invasion (RH = 3.7), tumour distance < or = 10 cm from the anal verge (RH = 3.0), postoperative radiotherapy (RH = 2.9) and a high carcinoembryonic antigen (CEA) score (RH = 1.8). In Dukes' C, only CEA score and gender were of prognostic significance. For Dukes' D, PL-TN was the only prognostic variable (RH = 1.7). Testing all patients in one multivariate analysis, Dukes' staging was the strongest and PL-TN the second strongest prognostic variable. The shortened survival for patients with low PL-TN levels is illustrated with lifetables.

Cloning of a cDNA encoding murine tetranectin

A full-length cDNA encoding murine tetranectin (TN) was isolated and cloned from a murine lung lambda ZAPII cDNA library. The complete nucleotide sequence was determined revealing an open reading frame encoding 202 amino acids (aa) including a signal peptide of 21 aa. An overall aa identity of 79% exists between the deduced aa sequences of human and murine TN, revealing a high evolutionary conservation of the protein. The highest expression of mouse TN was found in lung and skeletal muscle.

A potential role for tetranectin in mineralization during osteogenesis

Tetranectin is a protein shared by the blood and the extracellular matrix. Tetranectin is composed of four identical, noncovalently bound polypeptides each with a molecular mass of approximately 21 kD. There is some evidence that tetranectin may be involved in fibrinolysis and proteolysis during tissue remodeling, but its precise biological function is not known. Tetranectin is enriched in the cartilage of the shark, but the gene expression pattern in the mammalian skeletal system has not been determined. In the present study we have examined the expression pattern and putative function of tetranectin during osteogenesis. In the newborn mouse, strong tetranectin immunoreactivity was found in the newly formed woven bone around the cartilage anlage in the future bone marrow and along the periosteum forming the cortex. No tetranectin immunoreactivity was found in the proliferating and hypertrophic cartilage or in the surrounding skeletal muscle. Using an in vitro mineralizing system, we examined osteoblastic cells at different times during their growth and differentiation. Tetranectin mRNA appeared in the cultured osteoblastic cells in parallel with mineralization, in a pattern similar to that of bone sialoprotein, which is regarded as one of the late bone differentiation markers. To explore the putative biological role of tetranectin in osteogenesis we established stably transfected cell lines (PC12-tet) overexpressing recombinant tetranectin as evidenced by Northern and Western blot analysis and immunoprecipitation. Both control PC12 cells and PC12-tet cells injected into nude mice produced tumors containing bone material, as evidenced by von Kossa staining for calcium and immunostaining with bone sialoprotein and alkaline phosphatase antiserum. Nude mice tumors established from PC12-tet cells contained approximately fivefold more bone material than those produced by the untransfected PC12 cell line or by the PC12 cells transfected with the expression vector with no insert (Mann Whitney rank sum test, p < 0.01), supporting the notion that tetranectin may play an important direct and/or indirect role during osteogenesis. In conclusion, we have established a potential role for tetranectin as a bone matrix protein expressed in time and space coincident with mineralization in vivo and in vitro.

Tetranectin expression in human colonic neoplasia

The expression of tetranectin in colonic neoplasia was evaluated by determining the tissue distribution by immunohistological analysis of tissue sections and the antigen levels in tissue homogenates and plasma. In normal colonic mucosa tetranectin staining was predominantly found in the goblet cells whereas in adenocarcinomas this staining was confined to the tumour stroma. Colonic adenomas, benign precursors of adenocarcinomas, showed fewer tetranectin positive goblet cells and in some cases showed tetranectin expression in the stroma. Within the tissue homogenates no differences were found in the tetranectin levels between normal mucosa, adenomas and carcinomas. Patients with colonic cancer were found to have significantly decreased plasma tetranectin levels compared to healthy controls. Thus, colonic neoplasia is associated with a change in the tissue distribution of tetranectin, without an obvious change in the tissue level, and a low plasma tetranectin level.

The prognostic value of tetranectin immunoreactivity and plasma tetranectin in patients with ovarian cancer

BACKGROUND

Tetranectin (TN), a tetrameric, plasminogen-binding protein, was reduced in the plasma of patients with cancer and appears extracellularly in "stimulated" connective tissues, such as the proliferative, connective tissue response to carcinomas known as desmoplasia.

METHODS

Tissue samples from 37 patients with ovarian cancer were examined immunohistochemically for stromal and cellular TN. Plasma samples obtained before the primary surgery were quantitated for TN. The univariate log-rank test and the multivariate Cox proportional hazards regression model were used to analyze the prognostic function of the variables.

RESULTS

A significantly higher survival rate was found for patients with a low-stromal TN score and a high-plasma TN concentration, whereas the cellular TN score did not have any significance. A significant negative correlation was found between plasma TN and stromal TN (RS = -0.36; P = 0.03). Independent significant correlations were found between stromal immunoreactivity for TN and tumor grade (R = 0.67; P = 0.03) and between plasma TN and tumor stage (R = -0.29; P = 0.01).

CONCLUSIONS

This study gives great expectations to TN as a useful parameter for prognostic evaluation of patients with ovarian cancer. According to the correlations, stromal TN may partly originate from plasma and enhance proteolytic degradation in the interstitial tissue, a process necessary for the spread and growth of cancer. Because plasma TN measurements are only valid when taken preoperatively, it is of great value that stromal TN immunoreactivity of stored tumor tissue can be used as a prognostic factor for ovarian cancer.

Tetranectin: a novel secretory protein from human monocytes

Tetranectin is a recently described human plasma protein, which is found in most secretory cells throughout the body, including neutrophils. We present evidence for the presence of tetranectin in human monocytes and macrophages as well, and that these cells upon adherence or weak stimulation release a 20 kDa protein identified as tetranectin by immunoblotting. The amount of tetranectin released is 3-18 ng/h/10(6) monocytes. The possible influence of tetranectin on cellular functions was tested in migration and oxidative metabolism assays. Monocyte spontaneous migration was significantly stimulated by preincubation with purified tetranectin, whereas chemotactic and chemiluminescence responses to fMLP and C5a were unchanged. Neutrophil functions were not affected. It is concluded that tetranectin is secreted from human mononuclear phagocytes upon weak stimulation, and that the secreted tetranectin facilities spontaneous migration of these cells.

Prognostic value of serum tetranectin in patients with metastatic breast cancer

To evaluate serum tetranectin as a prognostic marker before first-line chemotherapy, serum levels were studied in 67 patients with metastatic breast cancer. In the Cox analyses, the relative risk (RR) for death of cancer varied with the cut-off level of serum tetranectin. A maximal RR of 5.0 was found for patients with serum tetranectin < or = 5.4 mg/l. The maximal RR of death for the other prognostic variables were multiple metastases 2.8, and for a poor performance status 2.0. Testing for the outcome, progressive disease, a maximal RR of 3.8 was found for patients with serum tetranectin < or = 5.3 mg/l, a maximal RR of 3.7 for multiple metastases and a maximal RR of 1.8 for a poor performance status. Significantly lower serum tetranectin values were found in patients with a poor treatment response compared to well responding patients. Serum tetranectrin seems to be useful as an additional prognostic factor in metastatic breast cancer.

The serine proteinase inhibitory proteins of the human intervertebral disc: their isolation, characterization and variation with ageing and degeneration

Serine proteinase inhibitory proteins (SPIs) were extracted from human disc tissues using 2 M GuHCl and subjected to CsCl density gradient ultracentrifugation. The SPIs recovered in the low buoyant density fractions (rho < or = 1.35 g/ml) were purified by a combination of gel-permeation, ion-exchange, trypsin affinity, and reverse-phase high performance chromatographies. Characterisation of the major disc SPI by polyacrylamide gel electrophoresis, isoelectric focussing, enzyme inhibition and pH stability studies indicated that this small molecular weight (12-14 kDa), highly basic (pI > 9.5), acid-stable but alkaline-labile protein possessed potent inhibitory activity against bovine pancreatic trypsin and chymotrypsin, and human leukocyte elastase and cathepsin G. Two-major and two-minor low molecular weight cationic SPI species were identified by reverse-phase HPLC. The predominant species was identical to a human articular cartilage SPI sharing amino terminal sequence homology with the mucus proteinase inhibitors (MPIs). It also cross-reacted with an antiserum to the MPIs and behaved identically to secretory leucocyte proteinase inhibitor (SLPI) when examined by reverse phase HPLC, and SDS PAGE. A higher molecular weight (54 kDa), anionic (pI approximately 4.6) SPI was also purified and identified as alpha 1-proteinase inhibitor (alpha 1-PI). Quantification of alpha 1-PI and the small molecular weight cationic disc inhibitors indicated that the latter were depleted in morphologically degenerate disc tissues while levels of alpha 1-PI were somewhat higher although a large proportion of the alpha 1-PI was inactive. A depletion of total SPI levels was evident overall in degenerate discs suggesting a functional role for these inhibitory proteins in the maintenance of IVD matrix homeostasis.

Primary structure of a protein isolated from reef shark (Carcharhinus springeri) cartilage that is similar to the mammalian C-type lectin homolog, tetranectin

During the course of characterization of low molecular weight proteins in cartilage, we have isolated a protein from reef shark (Carcharhinus springeri) cartilage that bears a striking resemblance to the tetranectin monomer originally described by Clemmensen et al. (1986, Eur. J. Biochem. 156, 327-333). The protein was isolated by extraction of neural arch cartilage with 4 M guanidine hydrochloride, dialysis of the extract to bring the guanidine to 0.4 M (reassociating proteoglycan aggregates), followed by cesium chloride density gradient removal of the proteoglycans. The amino acid sequence had 166 amino acids and a calculated molecular weight of 18,430. The shark protein was 45% identical to human tetranectin, indicating that it was in the family of mammalian C-type lectins and that it was likely to be a shark analog of human tetranectin. The function of tetranectin is unknown; it was originally isolated by virtue of its affinity for the kringle-4 domain of plasminogen. Sequence comparison of human tetranectin and the shark-derived protein gives clues to potentially important regions of the molecule.