Tetranectin Research Articles

Human plasminogen binding protein tetranectin: crystallization and preliminary X-ray analysis of the C-type lectin CRD and the full-length protein.

The recombinant human plasminogen binding protein tetranectin (TN) and the C-type lectin CRD of this protein (TN3) have been crystallized. TN3 crystallizes in the tetragonal space group P4(2)2(1)2 with cell dimensions a = b = 64.0, c = 75.7 A and with one molecule per asymmetric unit. The crystals diffract X-rays to at least 2.0 A resolution. A complete diffraction data set has been collected to 2.7 A resolution. The crystals of TN, obtained by the vapour-diffusion reverse salting-in method at 280 K, are rhombohedral, space group R3, with the hexagonal axes a = b = 89.1, c = 75.8 A, and diffract to at least 2.5 A. A full data set has been collected to 3.0 A. The asymmetric unit contains one monomer of TN. Molecular replacement solutions for TN3 and TN have been obtained using the structure of the C-type lectin CRD of rat mannose-binding protein as search model. The rhombohedral space group indicates that trimers of TN are formed in accordance with the observation of trimerization in solution.

Use of Tetranectin, CA-125 and Casa to Predict Residual Tumor and Survival at Second- and Third-Look Operations for Ovarian Cancer

Tetranectin (TN), CA-125 and CASA were measured in serum prior to 63 second-look and 5 third-look operations for ovarian cancer. Patients with residual tumor had significantly lower levels of TN and higher levels of CASA and CA-125 compared with tumor-free patients. The predictive values PVPos = 100% and PVNeg = 50.9% were found for TN at 9.3 mg/l. For CASA, a predictive value PVPos = 100% was found at 10 U/ml with a corresponding PVNeg = 52.7%. At the cut-off 35 U/ml for CA-125, the PVPos was 100% and the PVNeg = 53.6%. By combining the markers, PVNeg increased to 61.7% with a PVPos on 100%. Significantly differences in survival were found by lifetable analysis between patients tested as positive and negative respectively for any of the markers. Using multivariate Cox analyses, it was found that every marker had an independent prognostic function for survival.

Transforming growth factor- β1 downregulates dexamethasone-indunced tetranectin gene expression during the in vitro mineralization of the human osteoblastic cell line SV-HFO

In the present study, we examined the regulation of tetranectin gene expression using a human osteoblastic cell line, SV-HFO, that undergoes mineralization upon treatment with dexamethasone. We found that the expression of tetranectin and alkaline phosphatase mRNA was induced by dexamethasone treatment as evidenced by Northern blotting. When transforming growth factor- β 1 (TGF- β 1) was added together wwith dexamethasone to the SV-HFO cell cultures, the mineralization process was markedly suppressed and the expression of tetra nectin and alkaline phosphatase was downregulated in a dosedependent manner. These results demonstrate that the expression of tetranectin in these osteoblastic cells is regulated by dexamethasone and TGF- β 1 and that tetranectin expression is tightly linked to the process of mineralization.

Ovarian carcinoma serum markers and ovarian steroid activity — is there a link in ovarian cancer? A correlation of inhibin, tetranectin and CA-125 to ovarian activity and the gonadotropin levels

In a previous study, we have demonstrated that inhibin-production may be associated with improved survival and, also that tetranectin (TN) is a valuable prognostic marker in ovarian epithelial cancer. We investigated the possible correlation between inhibin, tetranectin, CA-125, ovarian steroid activity and the gonadotropin levels. Preoperative serum levels of the tumor markers inhibin, tetranectin (TN) and CA-125 were measured and related to ovarian steroid function and the pituitary-gonadal axis (gonadotropin) levels) in 28 postmenopausal ovarian cancer patients. The following median levels and 95% confidence limits were demonstrated for the tumor markers: Inhibin 0.4 U/1 (0.2-0.9), TN 8.9 mg/l (6.8–9.2), CA-125 160 kU/l (75–687). A significant inverse correlation was demonstrated between inhibin and the gonadotropins. The Spearman correlation coefficients showed a highly significant correlation of inhibin with the examined ovarian steroid hormones except DHEAS which also has a suprarenal component. This indicates a synthesis of inhibin and the steroid hormones from the same cell compartment as known from the normal ovary and an apparently intact negative feed back mechanism. Inhibin may be produced in the normal ovary as a defense mechanism against an elevated gonadotropin level and inhibin acts by lowering the gonadotropins or by altering their biological activity. Elevated values of the tumor markers TN and CA-125 due to gonadotropin stimulation could not be demonstrated but a signficant inverse correlation between TN and CA-125 was confirmed.

Cloning of a cDNA encoding murine tetranectin

A full-length cDNA encoding murine tetranectin (TN) was isolated and cloned from a murine lung λZAPII 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.

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

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. 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. 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). 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.

Pre-operative plasma tetranectin as a prognostic marker in ovarian cancer patients.

Plasma tetranectin (TN) was tested as a biochemical prognostic marker in ovarian cancer on 39 patients. In stage I + II the 5-year survival was 33% (2/6) if plasma TN was < or = 6.7 mg l-1 and 100% (15/15) with plasma TN > 6.7 mg l-1. For stage III + IV the survival was 0% (0/11) at 26 months for patients with plasma TN < or = 6.7 mg l-1 and 29% (2/7) after 5 years with plasma TN > 6.7 mg l-1. By multivariate testing the relative hazard (RH) of death was found to be 73 times higher in patients with plasma TN < or = 6.7 mg l-1 compared to patients with values above 6.7 mg l-1 (p < 0.001). For comparison, the maximal RH for the other tested variables were: 15 for advanced stage, 2.5 for grade, four for residual tumour and 2.5 for younger age.

Changes in plasma tetranectin following hip surgery with or without thrombotic complications

The fibrinolytic system seems to play a role in the development of postoperative thromboembolic complications (DVT). The newly described tetrameric protein tetranectin (TN), which has been found to enhance the activation of plasminogen to plasmin, therefore was studied in 55 patients who had total hip replacement and solely elastic stockings as physical thromboprophylaxis. No significant difference in plasma TN was found between the 5 patients with DVT and those without DVT, neither preoperatively or postoperatively at day 0, 1, 3, 7 or 10. A significant decrease in plasma TN was found from preoperative to postoperative values, indicating that TN may be a possible marker for other postoperative events. Because of the observed postoperative decrease it is important to consider the sampling time in the future research with TN.

Differences in tetranectin immunoreactivity between benign and malignant breast tissue

Tetranectin (TN) is a human, plasminogen kringle 4 binding plasma protein with ubiquitous cellular distribution and lectin-like characteristics. By means of the peroxidase-antiperoxidase staining technique a polyclonal and a monoclonal antibody were used to demonstrate TN within the intracellular as well as the extracellular compartment of invasive breast carcinoma. Whereas cell associated TN was universal showing only quantitative differences depending of the growth pattern of the tumor, 78 of 133 tumors displayed TN extracellularly as well. The occurrence of this stromal TN immunoreactivity was closely associated with desmoplasia, recognized morphologically by an increase in fibroblastic cells and immunohistochemically by an intense staining for the connective tissue glycoprotein fibronectin (FN). Benign breast tissue displayed a universal, intense cytoplasmic but no extracellular reaction for TN, with the exception of rare foci of granulation tissue and around dilated cysts. Functional studies have shown that human embryonal lung fibroblasts increase their release of TN to the growth medium upon stimulation. The presence of TN extracellularly within fibroblast-rich foci of desmoplasia (and granulation tissue) suggests that a similar increased release of the protein takes place in vivo during active states. Desmoplasia has been found to have a protective effect on tumor cell propagation and metastasis in a murine model. The molecular interactions, which are responsible for this effect, are undoubtedly complex. However, TN may, by its specific binding to kringle 4 of plasminogen and its high affinity for sulphated polysaccharides, add to the understanding of how plasminogen activation is modulated at the local extracellular level.

Tetranectin immunoreactivity in normal human tissues. An immunohistochemical study of exocrine epithelia and mesenchyme.

A recently discovered human plasma protein, tetranectin (TN), which has previously been demonstrated immunohistochemically within various endocrine tissues, was in this study identified in an additional number of epithelial and mesenchymal cells by two polyclonal antibodies and one monoclonal using the conventional immunoperoxidase staining technique and a modification of the CLONO-GLAD procedure. TN was found in endothelial and epithelial tissues, particularly in cells with a high turn-over or storage function such as gastric parietal and zymogenic cells, absorptive surface epithelium of the small intestine, ducts of exocrine glands and pseudostratified respiratory epithelium. Also mesenchymal cells produced a TN positive staining reaction, which was most conspicuous in mast cells, but also present in some lymphocytes, plasma cells, macrophages, granulocytes, striated and smooth muscle cells and fibroblasts. SDS-PAGE and Western blotting analysis of cultured human embryonal fibroblasts (WI-38) showed that the cells besides TN contain another protein with a molecular weight of 82,000. As this protein, however, reacted with our affinity purified antibodies it probably represents a precursor of TN or a protein with a molecular weight of approximately 60,000, which is covalently linked to TN. This and the fact that TN shows amino acid sequence homologies to the carboxyterminal part of the asialo-glycoprotein receptor and a cartilage proteoglycan core protein as well a binding affinity to plasminogen points to TN as being part of a larger molecule, which possibly has been cleaved by proteolysis at the cellular site and then passed into the blood, where it polymerizes into a tetramer.