Involvement of tenascin-C in proliferation and migration of laryngeal carcinoma cells

Distribution of tenascin-c and -X in rat TMJ development

In the neonatal and postnatal development of rat TMJ, tenascin-C and -X were detected in the muscle, bone matrix, connective tissue around the bone, and blood vessel of rats at E18 (18-days old embryo), 0-, and 5-days postnatal. The reaction of tenascin-X was also found in the connective tissue around the mandibular condyle. The mRNA of tenascin-C (600 bp) and -X (588 bp) was also detected in the developmental muscle with the level of tenascin-C mRNA moderately decreased during development. Therefore, tenascin-C and -X may have different effects on the connective tissue during development of TMJ.

Involvement of large tenascin-C splice variants in breast cancer progression

Alternative splicing of fibronectin-like type III (FNIII) repeats of tenascin-C (Tn-C) generates a number of splice variants. The distribution of large variants, typical components of provisional extracellular matrices that are up-regulated during tumor stroma remodeling, was here studied by immunoblotting and immunohistochemistry using a monoclonal antibody against the FNIII B domain (named 4C8MS) in a series of human breast cancers. Large Tn-C variants were found at only low levels in normal breast tissues, but were highly expressed at invading sites of intraductal cancers and in the stroma of invasive ductal cancers, especially at invasion fronts. There was a positive correlation between the expression of large Tn-C variants and the cell proliferation rate determined by immunolabeling of the Ki-67 antigen. Of the Tn-C recombinant fragments (all FNIII repeats or mFNIII FL, the conserved FNIII domain only, the epidermal growth factor-like domain, and the fibrinogen-like domain) which were expressed by CHO-K1 cells transfected with mouse Tn-C cDNAs, only the mFNIII FL enhanced in vitro migration and mitotic activity of mammary cancer cells derived from a Tn-C-null mouse. Addition of 4C8MS blocked the function of mFNIII FL. These findings provide strong evidence that the FNIII alternatively spliced region has important roles in tumor progression of breast cancer.

Markers for the development of early prostate cancer

Biochemical and genetic changes precede histologically identifiable changes accompanying cell transformation often by months or years. De-expression of the extracellular matrix adhesive glycoprotein tenascin and the cell-to-cell adherent protein E-cadherin have been suggested as markers of early neoplastic change in prostate epithelial cells. Previous studies have been inconclusive, probably due to epitope masking. This study examined 2,378 biopsy cores from 289 prostates using a heat antigen retrieval protocol at low pH to improve the accuracy of detection. Tenascin and E-cadherin de-expression was correlated with purinergic receptor and telomerase-associated protein labelling, as well as prostate-specific antigen (PSA) levels and Gleason scores. E-cadherin was a poor marker, as it was expressed in all lesions except carcinomas of the highest Gleason score. Tenascin was maximally expressed in the extracellular matrix and acinar basement membrane in normal and prostatic intraepithelial neoplasia tissue. In prostate cancer tissue, tenascin expression did not correlate with Gleason score but was significantly de-expressed as purinergic receptor and telomerase-associated protein expression increased. Marked changes in tenascin, telomerase-associated protein, and purinergic receptor expression were apparent before any histological abnormalities were visible by haematoxylin and eosin (H&E) stain, making these potential markers for early and developing prostate cancer. Moreover, the potential increased accuracy of diagnosis of underlying prostate cancer using purinergic receptor translocation (PRT) assessment suggests that PSA levels may be more accurate than has generally been supposed when apparent false negatives arising from H&E-based diagnoses are correctly categorized.

Tenascin-C expression and distribution in cultured human chondrocytes and chondrosarcoma cells

Tenascin-C (TNC) is an oligomeric glycoprotein of the extracellular matrix with several distinct isoforms variably expressed during embryogenesis, tumorogenesis, angiogenesis and wound healing. In the normal human adult, TNC is found in large concentrations in articular cartilage, suggesting tissue-specific function. The purpose of this study was to determine the specific in vitro TNC splicing patterns of articular chondrocytes and a human chondrosarcoma cell line. Cells were cultured in a three-dimensional bead system and TNC splice variant expression and distribution were examined with the use of Western blotting techniques, semi-quantitative reverse-transcription polymerase chain reaction and immunohistochemistry. At both the transcriptional and post-translational levels, the chondrocytes were found to express significantly higher levels of the smaller 220 kDa isoform (P < 0.01), which was predominantly incorporated into the matrix. The splicing pattern of the malignant cells was characterized by a higher proportion of the larger 320 kDa isoform which was extruded into the media. In vivo studies are necessary to verify the expression of the large TNC isoform in chondrosarcoma and the production and integration of the smaller isoform in normal chondroid matrix. In addition, elucidation of the biologic functions of the two major TNC isoforms may lead to the development of novel diagnostic and therapeutic approaches to chondrosarcoma.

The CXC chemokine cCAF stimulates precocious deposition of ECM molecules by wound fibroblasts, accelerating development of granulation tissue

BACKGROUND

During wound repair, fibroblasts orchestrate replacement of the provisional matrix formed during clotting with tenascin, cellular fibronectin and collagen III. These, in turn, are critical for migration of endothelial cells, keratinocytes and additional fibroblasts into the wound site. Fibroblasts are also important in the deposition of collagen I during scar formation. The CXC chemokine chicken Chemotactic and Angiogenic Factor (cCAF), is highly expressed by fibroblasts after wounding and during development of the granulation tissue, especially in areas where extracellular matrix (ECM) is abundant. We hypothesized that cCAF stimulates fibroblasts to produce these matrix molecules.

RESULTS

Here we show that this chemokine can stimulate precocious deposition of tenascin, fibronectin and collagen I, but not collagen III. Studies in culture and in vivo show that tenascin stimulation can also be achieved by the N-terminal 15 aas of the protein and occurs at the level of gene expression. In contrast, stimulation of fibronectin and collagen I both require the entire molecule and do not involve changes in gene expression. Fibronectin accumulation appears to be linked to tenascin production, and collagen I to decreased MMP-1 levels. In addition, cCAF is chemotactic for fibroblasts and accelerates their migration.

CONCLUSIONS

These previously unknown functions for chemokines suggest that cCAF, the chicken orthologue of human IL-8, enhances healing by rapidly chemoattracting fibroblasts into the wound site and stimulating them to produce ECM molecules, leading to precocious development of granulation tissue. This acceleration of the repair process may have important application to healing of impaired wounds.

Clinical impact and functional aspects of tenascin-C expression during glioma progression

The extracellular matrix protein tenascin-C is expressed in processes like embryogenesis and wound healing and in neoplasia. Tenascin-C expression in gliomas has been described previously; however, the relation to clinical data remains inconsistent. Generally, analysis of tenascin-C function is difficult due to different alternatively spliced isoforms. Our studies focus on changes in tenascin-C expression in human gliomas, correlating these changes with tumor progression and elucidating the functional role of the glioma cell-specific tenascin-C isoform pool. Eighty-six glioma tissues of different World Health Organization (WHO) grades were analyzed immunohistochemically for tenascin-C expression. The influence of the specific tenascin-C isoforms produced by glioblastoma cells on proliferation and migration was examined in vitro using blocking antibodies recognizing all isoforms. In general, tenascin-C expression increased with tumor malignancy. Perivascular staining of tenascin-C around tumor-supplying blood vessels was observed in all glioblastoma tissues, whereas in WHO II and III gliomas, perivascular tenascin-C staining appeared less frequently. The appearance of perivascular tenascin-C correlated significantly with a shorter disease-free time. Analysis of proliferation and migration in the presence of blocking antibodies revealed an inhibition of proliferation by around 30% in all 3 glioblastoma cell cultures, as well as a decrease in migration of 30.6-46.7%. Thus we conclude that the endogenous pool of tenascin-C isoforms in gliomas supports both tumor cell proliferation and tumor cell migration. In addition, our data on the perivascular staining of tenascin-C in WHO II and III gliomas and its correlation with a shorter disease-free time suggest that tenascin-C may be a new and potent prognostic marker for an earlier tumor recurrence.

Increased expression of tenascin in pheochromocytomas correlates with malignancy

Tenascin is a significant extracellular matrix glycoprotein, which is upregulated in various neoplasias and pathologic processes. Pheochromocytomas are rare tumors of the sympathoadrenal system, whose malignancy is almost impossible to predict. There are no histologic or chemical markers available that would define the malignant behavior of these tumors, except the discovery of metastases. In our search for new markers, we investigated the immunohistochemical expression of tenascin in a large number of pheochromocytomas and paragangliomas. Seven tumors were metastasized and were thus considered malignant. Normal adrenal medulla was tenascin negative. A striking difference was seen between malignant and benign pheochromocytomas. All malignant pheochromocytomas expressed stromal tenascin strongly or moderately, whereas most benign pheochromocytomas (28 of 37, 70%) showed no or only weak immunopositivity. The staining was strong or moderate also in 13 of 28 (46%) of the tumors that showed histologically suspicious features, here called borderline tumors. Paragangliomas showed a more heterogeneous staining pattern, and no significant difference was found between benign and malignant paragangliomas. To our knowledge, this is the first study to demonstrate the expression of tenascin in pheochromocytomas and particularly the enhanced expression in malignant pheochromocytomas. We therefore suggest that tenascin may be associated with the malignant transformation and metastasis of pheochromocytomas. It is also a potential marker predicting more aggressive behavior in pheochromocytomas.

Spatial and molecular organization of lymph node T cell cortex: a labyrinthine cavity bounded by an epithelium-like monolayer of fibroblastic reticular cells anchored to basement membrane-like extracellular matrix

Naive T cells encounter antigen-presenting cells within the cortex of lymph nodes to initiate primary immune responses. Within this T cell cortex is the reticular network (RN)--a system of collagen fibers and extracellular matrix (ECM) wrapped by fibroblastic reticular cells (FRC). We have investigated the distribution of various molecules, including ECM proteins and proteoglycans, in the T cell cortex of both human and rodent lymph node. We confirm and extend reports of matrix elements in the RN. In addition, we find that staining for the laminin-alpha3 chain and for tenascin reveals a 'hollow' reticular pattern, consistent with localization to the basement membrane-like covering of reticular fibers. In contrast, keratan sulfate is observed in a fine linear pattern within the RN, suggesting it is localized to the core of the fibers. Staining with the marker ER-TR7 indicates that FRC cover all identifiable ECM surfaces of the T cell cortex. Based on these findings and previous reports, we conclude that cortical lymphocytes migrate within a 'labyrinthine cavity' free of fibrillar ECM, distinguishing the T cell cortex from other loose connective tissues, and that the FRC lining of the cavity constitutes an epithelium-like boundary. We propose that this spatial organization facilitates ameboid leukocyte crawling along preformed paths of least resistance and that the basement membrane-like ECM of the FRC may facilitate fluid transport within the RN by limiting leakage from the fiber.

Tenascin-C modulates adhesion of cardiomyocytes to extracellular matrix during tissue remodeling after myocardial infarction

Tenascin-C (TNC), an extracellular matrix glycoprotein, plays important roles in tissue remodeling. TNC is not normally expressed in adults but reappears under pathologic conditions. The present study was designed to clarify the contribution of TNC to ventricular remodeling after myocardial infarction. We examined the expression of TNC after experimental myocardial infarction in the rat by immunohistochemistry and in situ hybridization. Within 24 hours of permanent coronary ligation, interstitial fibroblasts in the border zone started to express TNC mRNA. The expression of TNC was down-regulated on Day 7 and was no longer apparent by Day 14 after infarction. During the healing process, TNC protein and TNC-producing cells were found at the edges of the residual myocardium. Some of the TNC-producing cells were immunoreactive for alpha-smooth muscle actin. In culture, TNC increased the number of cardiomyocytes attached to laminin but inhibited the formation of focal contacts at costameres. The results indicate that during the acute phase after myocardial infarction, interstitial cells in the border zone synthesize TNC, which may loosen the strong adhesion of surviving cardiomyocytes to connective tissue and thereby facilitate tissue reorganization.

Tenascin-C splice variant adhesive/anti-adhesive effects on chondrosarcoma cell attachment to fibronectin

Tenascin-C is an oligomeric glycoprotein of the extracellular matrix that has been found to have both adhesive and anti-adhesive properties for cells. Recent elucidation of the two major TNC splice variants (320 kDa and 220 kDa) has shed light on the possibility of varying functions of the molecule based on its splicing pattern. Tenascin-C is prominently expressed in embryogenesis and in pathologic conditions such as tumorogenesis and wound healing. Fibronectin is a prominent adhesive molecule of the extracellular matrix that is often co-localized with tenascin-C in these processes. We studied the chondrosarcoma cell line JJ012 with enzyme-linked immunoabsorbance assays, cell attachment assays and antibody-blocking assays to determine the adhesive/anti-adhesive properties of the two major tenascin-C splice variants with respect to fibronectin and their effect on chondrosarcoma cell attachment. We found that the small tenascin-C splice variant (220 kDa) binds to fibronectin, whereas the large tenascin-C splice variant (320 kDa) does not. In addition, the small tenascin-C splice variant was found to decrease adhesion for cells when bound to fibronectin, but contributed to adhesion when bound to plastic in fibronectin-coated wells. Antibody blocking experiments confirmed that both the small tenascin-C splice variant and fibronectin contribute to cell adhesion when bound to plastic. The large tenascin-C splice variant did not promote specific cell attachment. We hypothesize that the biologic activity of tenascin-C is dependent on the tissue-specific splicing pattern. The smaller tenascin-C isoform likely plays a structural and adhesive role, whereas the larger isoform, preferentially expressed in malignant tissue, likely plays a role in cell egress and metastasis.