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

Advances in tenascin-C biology

Tenascin-C is an extracellular matrix glycoprotein that is specifically and transiently expressed upon tissue injury. Upon tissue damage, tenascin-C plays a multitude of different roles that mediate both inflammatory and fibrotic processes to enable effective tissue repair. In the last decade, emerging evidence has demonstrated a vital role for tenascin-C in cardiac and arterial injury, tumor angiogenesis and metastasis, as well as in modulating stem cell behavior. Here we highlight the molecular mechanisms by which tenascin-C mediates these effects and discuss the implications of mis-regulated tenascin-C expression in driving disease pathology.

Tenascin-C induces inflammatory mediators and matrix degradation in osteoarthritic cartilage

Background

Tenascin-C (TN-C) is an extracellular matrix glycoprotein that is involved in tissue injury and repair processes. We analyzed TN-C expression in normal and osteoarthritic (OA) human cartilage, and evaluated its capacity to induce inflammatory and catabolic mediators in chondrocytes in vitro. The effect of TN-C on proteoglycan loss from articular cartilage in culture was also assessed.

Methods

TN-C in culture media, cartilage extracts, and synovial fluid of human and animal joints was quantified using a sandwich ELISA and/or analyzed by Western immunoblotting. mRNA expression of TN-C and aggrecanases were analyzed by Taqman assays. Human and bovine primary chondrocytes and/or explant culture systems were utilized to study TN-C induced inflammatory or catabolic mediators and proteoglycan loss. Total proteoglycan and aggrecanase -generated ARG-aggrecan fragments were quantified in human and rat synovial fluids by ELISA.

Results

TN-C protein and mRNA expression were significantly upregulated in OA cartilage with a concomitant elevation of TN-C levels in the synovial fluid of OA patients. IL-1 enhanced TN-C expression in articular cartilage. Addition of TN-C induced IL-6, PGE₂, and nitrate release and upregulated ADAMTS4 mRNA in cultured primary human and bovine chondrocytes. TN-C treatment resulted in an increased loss of proteoglycan from cartilage explants in culture. A correlation was observed between TN-C and aggrecanase generated ARG-aggrecan fragment levels in the synovial fluid of human OA joints and in the lavage of rat joints that underwent surgical induction of OA.

Conclusions

TN-C expression in the knee cartilage and TN-C levels measured in the synovial fluid are significantly enhanced in OA patients. Our findings suggest that the elevated levels of TN-C could induce inflammatory mediators and promote matrix degradation in OA joints.

B domain containing Tenascin-C: a new urine marker for surveillance of patients with urothelial carcinoma of the urinary bladder?

BACKGROUND

ECM remodelling during tumorigenesis entails the re-occurrence of different Tn-C(L) splicing variants. In patients with urothelial carcinoma of the urinary bladder (UBC), B and C domain containing Tenascin-C (B(+) and C(+) Tn-C) urine levels were shown to be increased in case of muscle invasiveness. Thus, the present study was aimed at examining the ability of B(+) and C(+) Tn-C as potential urinary surveillance markers of UBC patients.

METHODS

Urine levels of B(+) and C(+) Tn-C were determined by ELISA in 35 UBC patients during a 2 year follow-up period after therapy and related to clinical diagnosis and histological stage in 4 defined groups representing typical courses of disease.

RESULTS

B(+) Tn-C levels showed significant differences between cases of tumour progression or regression. The urine levels of B(+) Tn-C could be used to discriminate between cases without tumour recurrence and such with tumour existence (cut-off value: 0.8 ng/ml) or between non-muscle invasive and muscle invasive tumour growth (cut-off value: 3.5 ng/ml).

CONCLUSIONS

Progression of UBC with time is accompanied by significant changes in urinary levels of B(+) Tn-C. Urinary B(+) Tn-C can therefore be suggested as a valuable urine surveillance marker in UBC follow-up care.

Tenascin C induces epithelial-mesenchymal transition-like change accompanied by SRC activation and focal adhesion kinase phosphorylation in human breast cancer cells

Tenascin C (TNC) is an extracellular matrix glycoprotein up-regulated in solid tumors. Higher TNC expression is shown in invading fronts of breast cancer, which correlates with poorer patient outcome. We examined whether TNC induces epithelial-mesenchymal transition (EMT) in breast cancer. Immunohistochemical analysis of invasive ductal carcinomas showed that TNC deposition was frequent in stroma with scattered cancer cells in peripheral margins of tumors. The addition of TNC to the medium of the MCF-7 breast cancer cells caused EMT-like change and delocalization of E-cadherin and β-catenin from cell-cell contact. Although amounts of E-cadherin and β-catenin were not changed after EMT in total lysates, they were increased in the Triton X-100-soluble fractions, indicating movement from the membrane into the cytosol. In wound healing assay, cells were scattered from wound edges and showed faster migration after TNC treatment. The EMT phenotype was correlated with SRC activation through phosphorylation at Y418 and phosphorylation of focal adhesion kinase (FAK) at Y861 and Y925 of SRC substrate sites. These phosphorylated proteins colocalized with αv integrin-positive adhesion plaques. A neutralizing antibody against αv or a SRC kinase inhibitor blocked EMT. TNC could induce EMT-like change showing loss of intercellular adhesion and enhanced migration in breast cancer cells, associated with FAK phosphorylation by SRC; this may be responsible for the observed promotion of TNC in breast cancer invasion.

Cellular and molecular mechanisms of pomegranate juice-induced anti-metastatic effect on prostate cancer cells

Prostate cancer is the second leading cause of cancer-related deaths among US males. Pomegranate juice (PJ), a natural product, was shown in a clinical trial to inhibit progression of this disease. However, the underlying mechanisms involved in the anti-progression effects of PJ on prostate cancer remain unclear. Here we show that, in addition to causing cell death of hormone-refractory prostate cancer cells, PJ also increases cell adhesion and decreases cell migration of the cells that do not die. We hypothesized that PJ does so by stimulating the expression and/or activation of molecules that alter the cytoskeleton and the adhesion machinery of prostate cancer cells, resulting in enhanced cell adhesion and reduced cell migration. We took an integrative approach to these studies by using Affimetrix gene arrays to study gene expression, microRNA arrays to study the non-coding RNAs, molecules known to be disregulated in cancer cells, and Luminex Multiplex array assays to study the level of secreted pro-inflammatory cytokines/chemokines. PJ up-regulates genes involved in cell adhesion such as E-cadherin, intercellular adhesion molecule 1 (ICAM-1) and down-regulates genes involved in cell migration such as hyaluranan-mediated motility receptor (HMMR) and type I collagen. In addition, anti-invasive microRNAs such as miR-335, miR-205, miR-200, and miR-126, were up-regulated, whereas pro-invasive microRNA such as miR-21 and miR-373, were down-regulated. Moreover, PJ significantly reduced the level of secreted pro-inflammatory cytokines/chemokines such as IL-6, IL-12p40, IL-1β and RANTES, thereby having the potential to decrease inflammation and its impact on cancer progression. PJ also inhibits the ability of the chemokine SDF1α to chemoattract these cancer cells. SDF1α and its receptor CXCR4 are important in metastasis of cancer cells to the bone. Discovery of the mechanisms by which this enhanced adhesion and reduced migration are accomplished can lead to sophisticated and effective prevention of metastasis in prostate and potentially other cancers.

Tenascins and the importance of adhesion modulation

Tenascins are a family of extracellular matrix proteins that evolved in early chordates. There are four family members: tenascin-X, tenascin-R, tenascin-W, and tenascin-C. Tenascin-X associates with type I collagen, and its absence can cause Ehlers-Danlos Syndrome. In contrast, tenascin-R is concentrated in perineuronal nets. The expression of tenascin-C and tenascin-W is developmentally regulated, and both are expressed during disease (e.g., both are associated with cancer stroma and tumor blood vessels). In addition, tenascin-C is highly induced by infections and inflammation. Accordingly, the tenascin-C knockout mouse has a reduced inflammatory response. All tenascins have the potential to modify cell adhesion either directly or through interaction with fibronectin, and cell-tenascin interactions typically lead to increased cell motility. In the case of tenascin-C, there is a correlation between elevated expression and increased metastasis in several types of tumors.

Expression of tenascin-C and its isoforms in the breast

Tenascin-C (TNC) is an extracellular matrix glycoprotein which is frequently up-regulated in a variety of pathological conditions including chronic inflammation and cancer. TNC has been implicated in the modulation of cell migration, proliferation, invasion and angiogenesis. Multiple isoforms of TNC can be generated through the alternative splicing of nine exons located in the fibronectin type III region of the molecule. The profile of isoforms expressed differs between cancers and normal breast, with the fully truncated TNC isoform being predominant in normal and benign tissues and higher molecular weight isoforms induced predominantly in cancer. The addition of extra domains within the fibronectin type III repeat domain greatly affects TNC function with multiple exon combinations available for splicing. Exons 14 and 16 are considered to be tumour-associated and have been shown to affect breast cell line invasion and growth in vitro to a greater extent than the full-length TNC isoform. This mini review will provide a summary of the literature to date regarding the expression of TNC isoforms in the breast and also discuss more recent developments in the field regarding exon AD1.

Association of invasion-promoting tenascin-C additional domains with breast cancers in young women

INTRODUCTION

Tenascin-C (TNC) is a large extracellular matrix glycoprotein that shows prominent stromal expression in many solid tumours. The profile of isoforms expressed differs between cancers and normal breast, with the two additional domains AD1 and AD2 considered to be tumour associated. The aim of the present study was to investigate expression of AD1 and AD2 in normal, benign and malignant breast tissue to determine their relationship with tumour characteristics and to perform in vitro functional assays to investigate the role of AD1 in tumour cell invasion and growth.

METHODS

Expression of AD1 and AD2 was related to hypoxanthine phosphoribosyltransferase 1 as a housekeeping gene in breast tissue using quantitative RT-PCR, and the results were related to clinicopathological features of the tumours. Constructs overexpressing an AD1-containing isoform (TNC-14/AD1/16) were transiently transfected into breast carcinoma cell lines (MCF-7, T-47 D, ZR-75-1, MDA-MB-231 and GI-101) to assess the effect in vitro on invasion and growth. Statistical analysis was performed using a nonparametric Mann-Whitney test for comparison of clinicopathological features with levels of TNC expression and using Jonckheere-Terpstra trend analysis for association of expression with tumour grade.

RESULTS

Quantitative RT-PCR detected AD1 and AD2 mRNA expression in 34.9% and 23.1% of 134 invasive breast carcinomas, respectively. AD1 mRNA was localised by in situ hybridisation to tumour epithelial cells, and more predominantly to myoepithelium around associated normal breast ducts. Although not tumour specific, AD1 and AD2 expression was significantly more frequent in carcinomas in younger women (age ≤40 years; P < 0.001) and AD1 expression was also associated with oestrogen receptor-negative and grade 3 tumours (P < 0.05). AD1 was found to be incorporated into a tumour-specific isoform, not detected in normal tissues. Overexpression of the TNC-14/AD1/16 isoform significantly enhanced tumour cell invasion (P < 0.01) and growth (P < 0.01) over base levels.

CONCLUSIONS

Together these data suggest a highly significant association between AD-containing TNC isoforms and breast cancers in younger women (age ≤40 years), which may have important functional significance in vivo.

Increased presence of stromal myofibroblasts and tenascin-C with malignant progression in canine mammary tumors

The aims of this study were to determine whether the appearance of stromal myofibroblasts and the expression of tenascin-C (Tn-C) correlate with the grade of malignancy in canine mammary tumors and to determine the main cellular source of Tn-C in these tumors. Single or double immunostaining using antibodies against α-smooth muscle actin (α-SMA) and Tn-C was performed on serial sections of normal canine mammary glands as well as those with lobular hyperplasia, simple adenoma, and simple carcinoma. Thirty-nine of 42 simple carcinomas (93%) exhibited stromal α-SMA-positive myofibroblasts and Tn-C expression. Only 6 of 11 cases of simple adenoma (55%) showed these changes, whereas no changes were observed in normal mammary gland tissue or cases of lobular hyperplasia. The distribution of stromal Tn-C correlated with the presence of myofibroblasts. However, Tn-C immunoreactivity was also occasionally observed in the basement membrane zone surrounding the myoepithelial layer in normal tissue, benign lesions, and tubulopapillary carcinomas. This pattern of staining was not related to the presence of myofibroblasts. The appearance of stromal myofibroblasts and expression of Tn-C were significantly correlated with higher histological grades of malignancy and vascular/lymphatic invasion in simple carcinomas. Stromal myofibroblasts appear to be a major cellular source of Tn-C and play an important role in the development of canine mammary tumors. The Tn-C expressed in the basement membrane zone of normal, hyperplastic, and neoplastic mammary tissue, which is likely produced by neighboring myoepithelial cells, may differ functionally from the Tn-C produced by myofibroblasts.

Apoptotic death of hematopoietic tumor cells through potentiated and sustained adhesion to fibronectin via VLA-4

It has been postulated that inactivated beta1-integrins are involved in the disordered growth of hematopoietic tumor cells. We recently found that TNIIIA2, a peptide derived from tenascin-C, strongly activates beta1-integrins through binding with syndecan-4. We show here that Ramos Burkitt's lymphoma cells can survive and grow in suspension but undergo apoptosis when kept adhering to fibronectin by stimulation with TNIIIA2. Other integrin activators, Mg(2+) and TS2/16 (an integrin-activating antibody), were also capable of inducing apoptosis. The inactivation of ERK1/2 and Akt and the subsequent activation of Bad were involved in the apoptosis. The results using other hematopoietic tumor cell lines expressing different levels of fibronectin receptors (VLA-4 and VLA-5) showed that potentiated and sustained adhesion to fibronectin via VLA-4 causally induces apoptosis also in various types of hematopoietic tumor cells in addition to Ramos cells. Because TNIIIA2 requires syndecan-4 as a membrane receptor for activation of beta1-integrins, it induced apoptosis preferentially in hematopoietic tumor cells, which expressed both VLA-4 and syndecan-4 as membrane receptors mediating the effects of fibronectin and TNIIIA2, respectively. Therefore, normal peripheral blood cells, such as neutrophils, monocytes, and lymphocytes, which poorly expressed syndecan-4, were almost insusceptible to TNIIIA2-induced apoptosis. The TNIIIA2-related matricryptic site of TN-C could contribute, once exposed, to preventing prolonged survival of hematopoietic malignant progenitors through potentiated and sustained activation of VLA-4.

Tenascin‐C levels in pseudosynovial fluid of loose hip prostheses

OBJECTIVE

Aseptic loosening is one of the most important problems that can occur after total hip arthroplasty (THA). In this study, we analysed levels of large tenascin-C (TN-C) variants and compared them in pseudosynovial fluid from patients with aseptic loosening after THA with those in synovial fluid from patients undergoing primary THA (control).

METHODS

Pseudosynovial fluid samples (n = 24) were obtained by aspiration at the time of revision THA performed due to aseptic loosening. Synovial fluid samples (n = 12) were obtained by aspiration at the time of primary THA. Expression of TN-C splice variants was examined using immunoblotting. TN-C levels were measured using an enzyme-linked immunosorbent assay (ELISA) system that we developed previously.

RESULTS

Western blotting showed the presence of large TN-C variants in pseudosynovial fluid of artificial joints with loosening. TN-C levels were approximately three times higher in pseudosynovial fluid of loose artificial joints (median 151.9 ng/mL) than in synovial fluid controls (median 50.1 ng/mL) (p = 0.035).

CONCLUSION

Levels of TN-C including large variant subunits are elevated in pseudosynovial fluid of loose artificial joints, indicating that TN-C is a useful novel biochemical marker of loose hip prostheses.

B and C domain containing tenascin-C: urinary markers for invasiveness of urothelial carcinoma of the urinary bladder?

PURPOSE

Surveillance of urothelial carcinoma of the urinary bladder (UBC) patients with respect to tumour recurrence and invasiveness is crucial for therapy and prognosis. Therefore, evaluation of non-invasive methods to monitor tumour progression is of high clinical interest. The study was aimed at investigating urinary concentrations of tenascin-C splicing domains for their value as tumour surveillance markers.

METHODS

Urinary concentration of B and C domain containing tenascin-C (Tn-C) was analysed by ELISA technology in 104 UBC patients, 11 patients with cystitis and 15 healthy donors as control. The investigation was supplemented by Tn-C immunohistochemistry and Western blotting.

RESULTS

A statistically significant increase in urinary concentrations of both Tn-C B and C domain with tumour progression could be evidenced. A concordant tumour-associated enhanced protein deposition in the carcinoma stroma could be demonstrated by immunohistochemistry in invasive UBC. Western blotting reveals proteolytic fragmentation of urinary Tn-C.

CONCLUSIONS

In summary, detection of Tn-C splicing domains in urine is suggested as a marker for the surveillance of UBC recurrence and invasiveness.

The regulation of tenascin expression by tissue microenvironments

Tenascins are a family of four extracellular matrix proteins: tenascin-C, X, R and W. The four members of the family have strikingly diverse patterns of expression during development and in the adult organism indicating independent mechanisms of regulation. In this review we illustrate that there are two types of tenascins, those that are significantly regulated by the tissue microenvironment (tenascin-C and tenascin-W), and those that have stabile, restricted expression patterns (tenascin-R and tenascin-X). We summarize what is known about the regulation of tenascin expression by transforming growth factor betas, fibroblast growth factors, platelet derived growth factors, as well as pro- and anti-inflammatory cytokines or hormones that either induce or inhibit expression of tenascins.

Human matrix metalloproteinases: characteristics and pathologic role in altering mesangial homeostasis

Matrix metalloproteinases are zinc dependent endopeptidases belonging to the M10 family of the metalloproteinase superfamily. They are ubiquitous enzymes, structurally and functionally related, with a high degree of sequence homology. They are primarily involved in extracellular matrix (ECM) turn-over and cell migration through their expanding repertoire of substrate affinities. Twenty three different forms of human MMPs have been described to be arranged in eight distinct structural classes. Their interactions with tissue inhibitors of metalloproteinases (TIMPs), and other indigenous inhibitors have been well documented. This manuscript reviews pertinent information available on matrix metalloproteinases and TIMPs in the literature. Light chain-mediated glomerular injury represents an excellent example of how metalloproteinases participate in altering mesangial homeostasis. Investigations regarding these conditions have shown that the physico-chemical characteristics of the light chains govern the pattern of renal damage that will ensue with the mesangium representing the critical site where pathological alterations are centered. The mesangium is either replaced or expanded depending on the light chains involved in the pathologic process.

Identification of VEGF-regulated genes associated with increased lung metastatic potential: functional involvement of tenascin-C in tumor growth and lung metastasis

Metastasis is the primary cause of death in patients with breast cancer. Overexpression of c-myc in humans correlates with metastases, but transgenic mice only show low rates of micrometastases. We have generated transgenic mice that overexpress both c-myc and vascular endothelial growth factor (VEGF) (Myc/VEGF) in the mammary gland, which develop high rates of pulmonary macrometastases. Gene expression profiling revealed a set of deregulated genes in Myc/VEGF tumors compared to Myc tumors associated with the increased metastatic phenotype. Cross-comparisons between this set of genes with a human breast cancer lung metastasis gene signature identified five common targets: tenascin-C(TNC), matrix metalloprotease-2, collagen-6-A1, mannosidase-alpha-1A and HLA-DPA1. Signaling blockade or knockdown of TNC in MDA-MB-435 cells resulted in a significant impairment of cell migration and anchorage-independent cell proliferation. Mice injected with clonal MDA-MB-435 cells with reduced expression of TNC demonstrated a significant decrease (P<0.05) in (1) primary tumor growth; (2) tumor relapse after surgical removal of the primary tumor and (3) incidence of lung metastasis. Our results demonstrate that VEGF induces complex alterations in tissue architecture and gene expression. The TNC signaling pathway plays an important role in mammary tumor growth and metastases, suggesting that TNC may be a relevant target for therapy against metastatic breast cancer.

Tenascin-W, a new marker of cancer stroma, is elevated in sera of colon and breast cancer patients

Tenascins are extracellular matrix proteins present during the development of organisms as well as in pathological conditions. Tenascin-W, the fourth and last member of the tenascin family remains the least well-characterized one. Our study aimed to evaluate the potential significance of tenascin-W as cancer biomarker by monitoring its presence in the serum of colorectal and breast cancer patients and its expression in colorectal tumor tissues. To measure serum tenascin-W levels, a sensitive sandwich-ELISA was established. Mean tenascin-W concentration in sera of patients with nonmetastatic colorectal cancer at time of diagnosis was highly increased compared to that of healthy volunteers. A similar tendency was observed for tenascin-C in the same patient cohort. However, the increase was much more striking for tenascin-W. We also detected elevated tenascin-W levels in sera of breast cancer patients. Furthermore, we could show a prominent expression of tenascin-W in extracts from colorectal tumor tissues by immunoblot analysis, whereas tenascin-W was not detectable in the corresponding normal colon mucosa. To confirm the western blot results, we performed immunohistochemistry of frozen sections of the same patients as well as of an additional, independently chosen collection of colorectal cancer tissues. In all cases, similarly to tenascin-C, tenascin-W was detected in the tumor stroma. Our results reveal a clear association between elevated levels of tenascin-W and the presence of cancer. These results warrant further studies to evaluate the potential value of serum and tissue tenascin-W levels as diagnostic, prognostic or monitoring biomarker in colorectal, breast and possibly other solid cancers.

Switch to an invasive growth phase in melanoma is associated with tenascin-C, fibronectin, and procollagen-I forming specific channel structures for invasion

Malignant melanomas are characterized by their high propensity to invade and metastasize, but the molecular mechanisms of these traits have remained elusive. Our DNA microarray analyses of benign nevi and melanoma tissue specimens revealed that the genes encoding extracellular matrix proteins tenascin-C (TN-C), fibronectin (FN), and procollagen-I (PCOL-I) are highly upregulated in invasive and metastatic melanomas. The expression and distribution of these proteins were further studied by immunohistochemistry in benign nevi, radially and vertically growing melanomas, sentinel node micrometastases, and macrometastases. TN-C was increased in all invasive tumours and metastases, especially at invasion fronts, but not in benign nevi or non-invasive melanomas. Significantly, the intensity of TN-C staining correlated with metastasis to sentinel lymph nodes, better than tumour thickness (Breslow). Moreover, TN-C, FN, and PCOL-I appeared to co-localize in the tumours and form tubular meshworks and channels ensheathing the melanoma cells. Our data suggest that melanoma invasion is associated with the formation of special channel-like structures, providing a new concept, structured tumour cell spreading. Altogether, these data provide potential new prognostic markers and therapeutic targets/strategies for preventing melanoma dissemination.

A peptide derived from tenascin-C induces beta1 integrin activation through syndecan-4

Tenascin-C (TN-C) is unique for its cell adhesion modulatory function. We have shown that TNIIIA2, a synthetic 22-mer peptide derived from TN-C, stimulated beta1 integrin-mediated cell adhesion of nonadherent and adherent cell types, by inducing activation of beta1 integrin. The active site of TNIIIA2 appeared cryptic in the TN-C molecule but was exposed by MMP-2 processing of TN-C. The following results suggest that cell surface heparan sulfate (HS) proteoglycan (HSPG), including syndecan-4, participated in TNIIIA2-induced beta1 integrin activation: 1) TNIIIA2 bound to cell surface HSPG via its HS chains, as examined by photoaffinity labeling; 2) heparitinase I treatment of cells abrogated beta1 integrin activation induced by TNIIIA2; 3) syndecan-4 was isolated by affinity chromatography using TNIIIA2-immobilized beads; 4) small interfering RNA-based down-regulation of syndecan-4 expression reduced TNIIIA2-induced beta1 integrin activation, and consequent cell adhesion to fibronectin; 5) overexpression of syndecan-4 core protein enhanced TNIIIA2-induced activation of beta1 integrin. However, treatments that targeted the cytoplasmic region of syndecan-4, including ectopic expression of its mutant truncated with the cytoplasmic domains and treatment with protein kinase Calpha inhibitor Gö6976, did not influence the TNIIIA2 activity. These results suggest that a TNIIIA2-related matricryptic site of the TN-C molecule, exposed by MMP-2 processing, may have bound to syndecan-4 via its HS chains and then induced conformational change in beta1 integrin necessary for its functional activation. A lateral interaction of beta1 integrin with the extracellular region of the syndecan-4 molecule may be involved in this conformation change.

Tenascin cytotactin epidermal growth factor-like repeat binds epidermal growth factor receptor with low affinity

Select epidermal growth factor (EGF)-like (EGFL) repeats of human tenascin cytotactin (tenascin C) can stimulate EGF receptor (EGFR) signaling, but activation requires micromolar concentrations of soluble EGFL repeats in contrast to subnanomolar concentrations of classical growth factors such as EGF. Using in silico homology modeling techniques, we generated a structure for one such repeat, the 14th EGFL repeat (Ten14). Ten14 assumes a tight EGF-like fold with truncated loops, consistent with circular dichroism studies. We generated bound structures for Ten14 with EGFR using two different approaches, resulting in two distinctly different conformations. Normal mode analysis of both structures indicated that the binding pocket of EGFR exhibits a significantly higher mobility in Ten14-EGFR complex compared to that of the EGF-EGFR complex; we hypothesized this may be attributed to loss of key high-affinity interactions within the Ten14-EGFR complex. We proved the efficacy of our in silico models by in vitro experiments. Surface plasmon resonance measurements yielded equilibrium constant K(D) of 74 microM for Ten14, approximately three orders of magnitude weaker than that of EGF. In accordance with our predicted bound models, Ten14 in monomeric form does not bind EGFR with sufficient stability so as to induce degradation of receptor, or undergo EGFR-mediated internalization over either the short (20 min) or long (48 h) term. This transient interaction with the receptor on the cell surface is in marked contrast to other EGFR ligands which cause EGFR transit through, and signaling from intracellular locales in addition to cell surface signaling.

Clinical significance of large tenascin-C spliced variant as a potential biomarker for colorectal cancer

BACKGROUND

Tenascin-C is an extracellular matrix protein forming various types of spliced variants. Low molecule variants are transiently present, but large spliced variants are predominantly overexpressed in proliferative processes or tumorigenesis in some varieties of cancer. However, the detection of the plasma level of large tenascin-C spliced variant (L-Tn-CSV) in colorectal cancer (CRC) has not been clarified. This study was performed to validate elevated plasma L-Tn-CSV levels as a possible biomarker for CRC.

MATERIALS AND METHODS

Plasma samples were obtained before resection and from time to time postoperatively and stored at -80 degrees C until assay. Plasma L-Tn-CSV levels were evaluated in patients with primary (n = 162) and with recurrent (n = 20) CRC, including 48 healthy volunteers, measured by ELISA.

RESULTS

The average plasma L-Tn-CSV concentrations of patients with primary CRC were 5,260 +/- 3,243.3 pg/ml and of patients with recurrent CRC 4,106 +/- 2,261.1 pg/ml, which were significantly elevated in comparison with those of healthy volunteers (2,364.3 +/- 7,49.6). The sensitivity for detecting CRC using plasma L-Tn-CSV was 56.6%, based on the mean +/- 2 SD of the concentrations of healthy controls (3,863.5), which was significantly higher than CEA (40.1%) and CA19-9 (23.6%). No obvious associations were evident between plasma L-Tn-CSV status and values of CEA and CA19-9 respectively. Statistically significant differences in plasma L-Tn-CSV were observed depending on tumor depth, lymph node metastasis, and TNM stage. Negative conversions of plasma L-Tn-CSV levels 6 months after resection were significantly higher in the completely curative resection group than in the non-curative groups (P < 0.001).

CONCLUSION

The plasma L-Tn-CSV may serve very well as a useful biomarker for tumor staging and postoperative monitoring of preoperatively positive CRC that is independent and exceeds conventional tumor markers.

Expression of large tenascin-C splice variants in synovial fluid of patients with rheumatoid arthritis

Tenascin-C (TN-C) is a hexameric glycoprotein component of extracellular matrix, and alternative RNA splicing creates two major TN-C size variants (the small and large variants). The large TN-C variants play key roles in many pathologic conditions in adults, including tumorigenesis, regeneration, and inflammation. This cross-sectional study compared levels of large TN-C variants in synovial fluid of patients with rheumatoid arthritis (RA) and osteoarthritis (OA). Synovial fluid samples were obtained from knees of 26 patients with advanced RA and 79 with advanced OA. Expression of TN-C splice variants was examined using Western blotting. The levels of large TN-C variants in synovial fluid were determined by an enzyme-linked immunosorbent assay. Synovium were analyzed for TN-C by immunohistochemistry. Immunoblotting showed the presence of large TN-C variants in synovial fluid from patients with RA and OA. However, levels of large TN-C variants were fourfold higher in RA samples compared with OA samples (p < 0.01). Synovial fluid levels of TN-C in RA did not correlate with C-reactive protein levels. Immunohistochemistry of the synovium showed stronger reactivity in RA samples than in OA samples. These results indicate that local synthesis of TN-C is increased during rheumatic disease.

Expression of large tenascin-C splice variants by hepatic stellate cells/myofibroblasts in chronic hepatitis C

BACKGROUND/AIMS

Earlier studies have suggested involvement of tenascin-C (TN-C) in liver fibrosis. Here, we examined expression of TN-C variants and types of alternatively spliced fibronectin-type III (FNIII) repeats in chronic hepatitis.

METHODS

Using three monoclonal antibodies against TN-C variants, immunohistochemical staining was performed and the correlation with histological parameters of chronic hepatitis C was examined. The cellular source was also determined and variant expression and their types were tested using isolated rat hepatic stellate cells (HSCs), liver myofibroblasts, and/or LI90 cells.

RESULTS

Large variants were not expressed in normal liver, but were up-regulated in chronic hepatitis, especially at sites of interface hepatitis and confluent necrosis, showing stronger correlations between staining intensity and these than with other parameters or fibrosis. TN-C deposition was closely correlated with increase in the number of alpha-smooth muscle actin-positive cells, i.e. activated HSCs/myofibroblasts, and in situ hybridization showed TN-C mRNA signals in the cells. Activated HSCs and myofibroblasts in culture highly expressed large variants of TN-C. In LI90 cells, sequencing of large variants revealed that the FNIII repeats D and A1/A4, followed by B, were preferentially included.

CONCLUSIONS

TN-C and its variants are produced by HSCs/myofibroblasts, suggesting important roles in liver fibrogenesis.

Tenascin-C patterns and splice variants in actinic keratosis and cutaneous squamous cell carcinoma

BACKGROUND

Tenascin-C (Tn-C) is an extracellular matrix protein with multiple functions that is present at low levels in normal tissues, but which is highly present in various tumours. The mRNA expression and protein level of Tn-C including its various isoforms have not been investigated comprehensively so far in cutaneous squamous cell carcinoma (SCC) and the precursor lesion actinic keratosis (AK).

OBJECTIVES

To assess the dysregulated expression and splice variants of Tn-C in cutaneous squamous cell dysplasia and carcinoma.

METHODS

Biopsies from 66 patients (or representative subsets) that comprised 25 specimens from normal skin, 19 AK and 22 cutaneous SCC were analysed for Tn-C splice variants using splice-specific primers. The amount of Tn-C mRNA was investigated by quantitative real-time reverse transcription-polymerase chain reaction. In addition, the presence of Tn-C protein was analysed in sections of paraffin-embedded tissues using immunohistochemistry.

RESULTS

The large Tn-C splice variant was present in only 5% of normal skin samples, in comparison with 63% of AK (P < 0.001) and 88% of SCC (P < 0.001). Tn-C mRNA expression was significantly increased in AK and SCC compared with normal skin (P < 0.001). The corresponding proteins were rarely detected in cells of the vascular epithelial layers and perifollicular layers of some normal skin specimens, and their spatial localization expanded into the papillary dermis of AK. The largest amount and the widest distribution were found in samples of SCC, in which Tn-C was located in the basal cells at the tumour invasion front and additionally in the papillary dermis and reticular dermis.

CONCLUSIONS

Tn-C is present in the dermis, its expression is increased during skin cancer development, and the large splice variant is characteristic for AK and SCC, which may prove useful for diagnostic approaches in cutaneous SCC.

A quantitative observation and imaging of single tumor cell migration and deformation using a multi-gap microfluidic device representing the blood vessel

A microfluidic device was developed for quantifying the migratory and deformability capabilities of a single tumor cell using direct imaging. It was fabricated using photolithography and is made of polydimethysiloxane. Chemotaxis approach was used for directing cell movement, using 10 microm microgaps to restrict the migration to a single cell. Each cell's migration rate is quantified as a measure of its distance traveled over time taken. Real-time recording of cell deformation under physiological flow was performed, and the elongation index and surface area change of the cells were compared. Three human tumor cell lines viz. HepG2, HeLa and MDA-MB-435S were used to verify the operation and methodology of the device. Their migration rates ranged from 5 to 15 microm/h, consistent with other scientific reports. By reducing the microgap width to 3 microm, it was found that the cells moved along the row of microgaps but were unable to migrate across the microgaps. Subsequent deformation of the cells through the gaps further showed that their migratory capability might be governed by their deformation ability and the deformation stress on their membranes. The strategy of targeting cancer cell membrane for rupture may provide a therapy for metastasis. Being a valuable tool for rapid quantification of a single cell's migratory capability, this device should be helpful for pharmacologic and drug screening, investigation of factors that regulate cell migration and deformation.

Timely DNA vaccine combined with systemic IL-12 prevents parotid carcinomas before a dominant-negative p53 makes their growth independent of HER-2/neu expression

Double transgenic mice overexpressing the transforming rat HER-2/neu oncogene and the mutated p53, with both dominant-negative and a gain-of-function properties, display early aggressive and metastasizing parotid tumors. Multiple acinar and ductal hyperplasia foci overexpressing the HER-2/neu gene product are evident at wk 5 and progress to poorly differentiated carcinoma by wk 7. Mice die before wk 18 with invasive carcinomas and multiple metastases that no longer express HER-2/neu. A combination of repeated electroporations of plasmids coding for the extracellular and transmembrane domains of the rat HER-2/neu receptor with systemic IL-12 administrations started when the parotids that present diffuse hyperplasia protected all female and 50% of the male mice until the close of the experiment at wk 40. This combined treatment began when multifocal in situ carcinomas that were already present cured 33% of the females and 25% of the males. The most prominent immunologic features associated with the antitumor protection were the production of high titers of anti-HER-2/neu Abs and the nonappearance of cell-mediated cytotoxic reactivity. In conclusion, anti-HER-2/neu vaccination combined with systemic IL-12 control parotid carcinomas as far as p53 mutation makes their growth independent of HER-2/neu expression.

Serum tenascin-C might be a novel predictor of left ventricular remodeling and prognosis after acute myocardial infarction

OBJECTIVES

We investigated clinical implications of serum tenascin-C (TN-C) levels in patients with acute myocardial infarction (AMI).

BACKGROUND

Tenascin-C, an extracellular matrix glycoprotein, is not normally expressed in the adult heart, but transiently appears during pathological conditions and plays important roles in tissue remodeling.

METHODS

Serum TN-C levels were measured by ELISA in 105 AMI patients at various time points, in 10 old myocardial infarction (OMI) patients, and 20 normal controls.

RESULTS

The mean serum TN-C level of AMI patients on admission (63.3 +/- 30.1 ng/ml) was significantly higher than that of controls and OMI (30.9 +/- 8.8 ng/ml and 27.4 +/- 11.7 ng/ml, respectively, p < 0.01), and peaked at 5 days (83.2 +/- 43.0 ng/ml). Follow-up examination (mean: 43.9 +/- 19.6 months) revealed that 25 of 105 AMI (23.8%) patients showed left ventricular (LV) remodeling (> or =20% end-diastolic volume increase), and in 15 (14.3%), major adverse cardiac events (MACE) were detected. The peak TN-C level was significantly higher in the remodeling group than the nonremodeling group (112 +/- 37 ng/ml vs. 66 +/- 29 ng/ml; p < 0.0001). By receiver-operating characteristic (ROC) analysis, TN-C levels clearly discriminated prediction of LV remodeling and MACE compared with other variables including plasma B-type natriuretic peptide, creatine kinase-MB, and LV function. Best predictive values of TN-C for remodeling and MACE were 84.8 and 92.8 ng/ml, respectively. Cox proportional hazards model analysis showed that TN-C was an important independent predictor of MACE.

CONCLUSIONS

The findings suggest that serum TN-C levels might be useful in predicting LV remodeling and prognosis after AMI.

Tenascin C and annexin II expression in the process of pancreatic carcinogenesis

Tenascin C (TNC) is a component of the provisional extracellular matrix (ECM) that characterizes solid tumours. Cell surface annexin II is a high-affinity receptor for large TNC splice variants. The aim of this study was to analyse whether TNC and annexin II play a role in the development of pancreatic ductal adenocarcinoma (PDAC). PDAC is characterized by a rich ECM populated by pancreatic stellate cells, which play a crucial role in pancreatic desmoplasia. The mRNA and protein levels of TNC and of annexin II were analysed in pancreatic tissues by DNA array, quantitative reverse transcriptase-polymerase chain reaction (QRT-PCR) and immunohistochemistry. TNC large splice variants were detected by RT-PCR. Enzyme linked immunosorbent assay (ELISA) was used to measure TNC levels in serum and culture supernatants. TNC and annexin II mRNA levels were significantly higher in pancreatic cancer tissues than in the normal pancreas. TNC expression was detected with increased frequency in the progression from PanIN-1 lesions to PDAC, and a parallel switch from cytoplasmic to cell surface expression of annexin II was observed. Large TNC transcripts were found in pancreatic cancer and in chronic pancreatitis, but not in the normal pancreas. TNC expression was demonstrated in pancreatic stellate cells, where it could be induced by tumour necrosis factor alpha (TNFalpha), transforming growth factor beta1 (TGF-beta1) and by cancer cell supernatants supplemented with TGF-beta1. In conclusion, the expression of TNC and cell surface annexin II increases in the progression from low-grade PanIN lesions to pancreatic cancer. Pancreatic stellate cells are identified as a source of TNC in pancreatic tissues, possibly under the influence of soluble factors released by the tumour cells.

Tenascin-C induced signaling in cancer

Tenascin-C is an adhesion modulatory extracellular matrix molecule that is highly expressed in the microenvironment of most solid tumors. High tenascin-C expression reduces the prognosis of disease-free survival in patients with some cancers. The possible role of tenascin-C in tumor initiation and progression is addressed with emphasis on underlying signaling mechanisms. How tenascin-C affects malignant transformation, uncontrolled proliferation, angiogenesis, metastasis and escape from tumor immunosurveillance is summarized. Finally, we discuss how the phenotypes of tenascin-C knock-out mice may help define the roles of tenascin-C in tumorigenesis and how this knowledge could be applied to cancer therapy.

Circulating level of large splice variants of tenascin-C is a marker of piecemeal necrosis activity in patients with chronic hepatitis C

BACKGROUND

It has been reported that histological activity index and piecemeal necrosis are good factors to evaluate the prognosis in patients with chronic hepatitis C (CHC). Thus, there is a need for simple and noninvasive means to assess disease activity and piecemeal necrosis in patients with CHC. In this study, we measured the serum concentrations of large splice variants of tenascin-C (cTN-C) in patients with CHC, and examined their correlation with the degree of inflammatory activity and fibrosis as evaluated in liver biopsy specimens.

METHODS

The serum levels of cTN-C in 150 patients with CHC and 50 healthy volunteers were measured by enzyme-linked immunosorbent. The histology of liver biopsy specimens was also evaluated following the Desmet's grading/staging system and the Ishak's classification. Liver specimens obtained by biopsy were also immunohistochemically evaluated with anti-human tenascin-C antibodies.

RESULTS

Serum cTN-C concentrations were significantly higher in CHC patients than in healthy volunteers (P < 0.0001). The levels of cTN-C showed no significant difference among the fibrosis stages as assessed by the Desmet's grading/staging system and Ishak's classification scores. However, the concentration of cTN-C was significantly correlated with the grade of activity. According to the Ishak's classification, the concentration of cTN-C was increased in proportion to the degree of piecemeal necrosis. Specific immunostaining of cTN-C was observed in limited areas of piecemeal necrosis but not in fibrotic areas.

CONCLUSION

The measurement of serum levels of cTN-C is a useful marker of the activity of CHC, in particular of the degree of piecemeal necrosis.

Tenascin-C protein expression and mRNA splice variants in thyroid carcinoma

Tenascin-C (Tn-C) is a matricellular protein involved in the initial and intermediate stages of cell adhesion. The present study is the first undertaken to comparatively investigate Tn-C in neoplastic, non-neoplastic thyroid lesions and normal thyroid tissues. Forty-eight thyroid specimens were studied immunohistochemically using a monoclonal antibody against Tn-C. Immunohistochemistry was supplemented by RT-PCR analysis of the two Tn-C mRNA splice variants in 13 thyroid cancer cell lines. Normal and non-neoplastic tissues were devoid of Tn-C, as well as follicular neoplasms, Huerthle-cell and anaplastic carcinomas. Most papillary carcinomas showed a focally intensive extracellular staining, localized in the connective tissue stroma, whereas most medullary carcinomas showed a staining in the connective tissue but also in intracellular location mainly. RT-PCR analysis detected Tn-C mRNA in all thyroid cancer cell lines with prevalence of the large splice variant in all but the medullary line, characterized by a higher Tn-Csmall:Tn-Clarge ratio. In conclusion, Tn-C re-expression has been observed in papillary and medullary thyroid carcinomas with different staining patterns accompanied by the prevalence of different mRNA splice variants in cell cultures. It seems possible that Tn-C is rather synthesized by tumor cells than by activated stromal cells.

Tenascin-C—coated platinum coils for acceleration of organization of cavities and reduction of lumen size in a rat aneurysm model

Object. Detachable platinum coils are widely used in the endovascular treatment of intracranial aneurysms. The use of coil placement produces a higher incidence of aneurysm recurrence compared with surgical clipping. To reduce the incidence of recurrence by promoting clot organization, the authors designed a platinum coil coated with tenascin-C (TNC), an extracellular matrix glycoprotein, and then histologically examined tissue responses.

Methods. Platinum coils were prepared by successive coatings with cationic polyethyleneimine and anionic heparin and then TNC or basic fibroblast growth factor (bFGF) was immobilized by affinity binding to the heparin. Six unmodified, six heparin-coated, six bFGF-coated, or eight TNC-coated platinum coils were inserted into ligated common carotid arteries (CCAs) of adult male rats, and CCA segments were harvested after 14 or 28 days.

The percentages of organized areas occupying the luminal cavity in unmodified, heparin-coated, bFGF-coated, and TNC-coated groups were 4.8 ± 4.6, 1.6 ± 1.1, 17.9 ± 10.7, and 93.4 ± 6.9%, respectively. In addition, the mean lumen size in the TNC-coated group (0.35 ± 0.23 mm2) was reduced to less than half that of the unmodified group (0.72 ± 0.21 mm2). Immunohistochemical analysis revealed that α—smooth muscle actin—positive cells were a major cellular component of the organized tissue within the TNC-coated coils but not in the bFGF group. Collagen fibrils in the organized areas were also much thicker and denser with TNC-coated coils than with bFGF-coated coils.

Conclusions. Placement of TNC-coated coils can remarkably accelerate organization of luminal cavities and reduce their volume, providing improved efficacy of these coils for endovascular embolization.

Matrix metalloproteinases and mesangial remodeling in light chain-related glomerular damage

BACKGROUND

Matrix metalloproteinases (MMPs) belong to the zinc endopeptidase subgroup of the metalloproteinase superfamily and are primarily involved in extracellular matrix (ECM) remodeling. Alterations of the mesangial ECM in AL-amyloidosis (AL-Am) and light chain deposition disease (LCDD) are crucial in their pathogeneses as two divergent entities.

METHODS

Protein expression patterns of five MMPs (MMP-1, 2, 3, 7, and 9) in renal tissues obtained from autopsies and kidney biopsies, and cultured human mesangial cells (HMCs) treated with light chains obtained from the urines of patients with AL-Am and LCDD were analyzed. MMP mRNA expressions were determined in glomeruli following laser capture microdissection and selective MMP microarray. Zymography was used to assess MMP activity.

RESULTS

The average glomerular MMP expression was 6 times greater in AL-Am than LCDD and negative control renal tissues with different expression profiles: MMP-1, 7 > 9 > 3 > 2, MMP-1 > 2, 9 > 3 > 7, and MMP-2, 3, 7 > 9 > 1, respectively. Microdissected glomeruli and HMCs treated with light chains expressed higher levels of MMP mRNA and proteins in AL-Am than LCDD. Zymography was used to assess activity demonstrating increased MMP-2 in AL-Am.

CONCLUSION

Altered expressions of MMPs play a key role in the pathogenesis of AL-Am and LCDD. MMPs were more highly expressed in AL-Am compared to LCDD.

Similarities and dissimilarities of branching and septation during lung development

The lungs of small premature babies are at a developmental stage of finalizing their airway tree by a process called branching morphogenesis, and of creating terminal gas exchange units by a mechanism called septation. If the branching process is disturbed, the lung has a propensity to be hypoplastic. If septation is impaired, the terminal gas exchange units, the alveoli, tend to be enlarged and reduced in number, an entity known as bronchopulmonary dysplasia. Here, we review current knowledge of key molecules influencing branching and septation. In particular, we discuss the molecular similarities and dissimilarities between the two processes of airspace enlargement. Understanding of the molecular mechanisms regulating branching and septation may provide perinatologists with targets for improving lung growth and maturation.

Tenascin-C regulates recruitment of myofibroblasts during tissue repair after myocardial injury

Tenascin-C (TN-C) is an extracellular matrix molecule that is expressed during wound healing in various tissues. Although not detectable in the normal adult heart, it is expressed under pathological conditions. Previously, using a rat model, we found that TN-C was expressed during the acute stage after myocardial infarction and that alpha-smooth muscle actin (alpha-SMA)-positive myofibroblasts appeared in TN-C-positive areas. In the present study, we examined whether TN-C controls the dynamics of myofibroblast recruitment and wound healing after electrical injury to the myocardium of TN-C knockout (TNKO) mice compared with wild-type (WT) mice. In TNKO mice, myocardial repair seemed to proceed normally, but the appearance of myofibroblasts was delayed. With cultured cardiac fibroblasts, TN-C significantly accelerated cell migration, alpha-SMA expression, and collagen gel contraction but did not affect proliferation. Using recombinant fragments of murine TN-C, the functional domain responsible for promoting migration of cardiac fibroblasts was mapped to the conserved fibronectin type III (FNIII)-like repeats and the fibrinogen (Fbg)-like domain. Furthermore, alternatively spliced FNIII and Fbg-like domains proved responsible for the up-regulation of alpha-SMA expression. These results indicate that TN-C promotes recruitment of myofibroblasts in the early stages of myocardial repair by stimulating cell migration and differentiation.

Diagnostic utility of tenascin-C for evaluation of the activity of human acute myocarditis

Tenascin-C (TN-C) is an extracellular matrix protein that is expressed transiently in close association with tissue remodelling in various body sites. In the heart, TN-C is only present during early stages of development, is not expressed in the normal adult, but reappears in pathological states. The purpose of this study was to analyse the expression of TN-C in myocardial tissue from myocarditis patients, and to evaluate the diagnostic value of immunostaining for TN-C in the assessment of inflammatory activity in biopsy specimens. A total of 113 biopsy specimens obtained from 32 patients with a clinical diagnosis of acute myocarditis were examined by immunohistochemistry and in situ hybridization for TN-C. The immunostaining was semi-quantified and compared with histological diagnosis according to the Dallas criteria. Furthermore, serial biopsies from 22 patients were taken during convalescence, and sequential changes in TN-C levels were analysed. Expression of TN-C was specifically detected in endomyocardial biopsy specimens from patients with active-stage inflammation, and disappeared in healed stages. The degree of expression of TN-C correlated with the severity of histological lesions. These data suggest that TN-C reflects disease activity in cases of human myocarditis. Immunostaining for TN-C could enhance the sensitivity and accuracy of diagnosis using biopsy specimens.

Tenascin-W is found in malignant mammary tumors, promotes alpha8 integrin-dependent motility and requires p38MAPK activity for BMP-2 and TNF-alpha induced expression in vitro

Tenascins represent a family of extracellular matrix glycoproteins with distinctive expression patterns. Here we have analyzed the most recently described member, tenascin-W, in breast cancer. Mammary tumors isolated from transgenic mice expressing hormone-induced oncogenes reveal tenascin-W in the stroma around lesions with a high likelihood of metastasis. The presence of tenascin-W was correlated with the expression of its putative receptor, alpha8 integrin. HC11 cells derived from normal mammary epithelium do not express alpha8 integrin and fail to cross tenascin-W-coated filters. However, 4T1 mammary carcinoma cells do express alpha8 integrin and their migration is stimulated by tenascin-W. The expression of tenascin-W is induced by BMP-2 but not by TGF-beta1, though the latter is a potent inducer of tenascin-C. The expression of tenascin-W is dependent on p38MAPK and JNK signaling pathways. Since preinflammatory cytokines also act through p38MAPK and JNK signaling pathways, the possible role of TNF-alpha in tenascin-W expression was also examined. TNF-alpha induced the expression of both tenascin-W and tenascin-C, and this induction was p38MAPK- and cyclooxygenase-dependent. Our results show that tenascin-W may be a useful diagnostic marker for breast malignancies, and that the induction of tenascin-W in the tumor stroma may contribute to the invasive behavior of tumor cells.

Co-stimulation of human breast cancer cells with transforming growth factor-beta and tenascin-C enhances matrix metalloproteinase-9 expression and cancer cell invasion

Transforming growth factor-beta (TGF-beta), tenascin-C (TN-C) and matrix metalloproteinases (MMPs) have been demonstrated independently to be associated with disease progression and poor prognosis in patients with breast cancer. The present study explored effects of TGF-beta and TN-C on MMP-9 expression and cancer invasion. An experimental study was designed to analyse MDA-MB-231 breast cancer cells, known for their high invasiveness, after stimulation with TGF-beta1 and/or TN-C. TGF-beta1 stimulated TN-C expression in the cells. Co-stimulation of MDA-MB-231 cells with TN-C and TGF-beta increased MMP-9 expression at both the gene (28-fold) and the protein levels. The in vitro invasion also increased (4-fold). GM6001 inhibited the invasion induced by the co-stimulation. The combined effect of TN-C and TGF-beta resulted in enhanced MMP-9 expression and cancer invasion in vitro.

Fetal oxygen tension promotes tenascin-C-dependent lung branching morphogenesis

Tenascin-C (TN-C) is a mesenchyme-derived extracellular matrix (ECM) glycoprotein required for fetal lung branching morphogenesis. Given that the low oxygen (O(2)) environment of the fetus is also essential for normal lung branching morphogenesis, we determined whether fetal O(2) tension supports this process by promoting TN-C expression. Initial studies showed that 15-day fetal rat lung explants cultured for 2 days at 3% O(2) not only branched well, but they also expressed higher levels of TN-C when compared to lungs maintained at 21% O(2), which branched poorly. Antisense oligonucleotide studies demonstrated that TN-C produced in response to 3% O(2) was essential for lung branching morphogenesis. As well, exogenous TN-C protein was shown to promote branching of lung epithelial rudiments cultured at 21% O(2). Because ECM-degrading proteinases are capable of catabolizing TN-C protein, we reasoned that 3% O(2) might promote TN-C deposition by limiting the activity of these enzymes within the fetal lung. Consistent with this idea, gelatin zymography showed that the activity of a 72-kDa gelatinase, identified as matrix metalloproteinase-2 (MMP-2), was lower at 3% O(2) vs. 21% O(2). Furthermore, pharmacologic inhibition of MMP-2 activity in fetal lung explants cultured at 21% O(2) resulted in increased TN-C deposition within the mesenchyme, as well as enhanced branching morphogenesis. Collectively, these studies indicate that fetal O(2) tension promotes TN-C-dependent lung epithelial branching morphogenesis by limiting the proteolytic turnover of this ECM component within the adjacent mesenchyme.

Functional regulation of T lymphocytes by modulatory extracellular matrix proteins

In addition to the major structural molecules, which are constitutively present in extracellular matrices, several proteins appear in the extracellular matrix only at specific stages in development or in association with specific pathological conditions. These proteins include thrombospondin-1 and -2, tenascin C, osteopontin, members of the cysteine-rich 61/connective tissue growth factor/nephroblastoma overexpressed family, and secreted protein acidic and rich in cysteine (osteonectin). These proteins play important roles in regulating cell fate during development and in the pathogenesis of several diseases in adult animals. We will review the interactions of T cells with this class of molecules and their resulting effects on T cell behavior. Receptors and signal transduction pathways that mediate the actions of matricellular proteins on T cells are beginning to be defined. Transgenic mice are providing new insights into the functions of these proteins in vivo and are yielding insights into the significance of their reported dysregulation in several human diseases.

A visual-quantitative analysis of fibroblastic stromagenesis in breast cancer progression

One fundamental difference between normal and transformed cells is the way they interact with their immediate environment. Exploring this difference is crucial for understanding the pathobiology of cancer progression. Benign epithelial tumors are constrained by a surrounding stroma consisting, among other cells, of fibroblasts embedded within fibrillar three-dimensional matrices. However, at a critical point in tumor progression, tumor cells become altered and overcome the barrier, inducing changes in the stroma, which promote, rather than impede, tumor progression. Inherited or acquired genetic aberrations affecting mammary gland epithelia are usually blamed for promoting neoplasia in individuals at "high risk" for breast cancer. However, in addition to these epithelial aberrations certain individuals possess permissive breast stroma. The occurrence of this permissive stroma results in a predisposition for cancer initiation or progression. Here we review stromagenic stages, experimental 3D systems, and discuss digital imaging analyses suitable for uncovering the mechanisms behind fibroblastic breast stromagenesis.

Prognostic significance of tenascin-C expression in superficial and invasive bladder cancer

AIMS

Tenascin-C (Tn-C) is an extracellular matrix glycoprotein that is upregulated in malignant tumours. Tn-C promotes cell growth, cell migration, and angiogenesis. It has been suggested to be a prognostic factor in various types of malignant tumours, but there is little information on its significance in bladder cancer with regard to overall survival (OS) and recurrence free survival (RFS).

METHODS

Tn-C expression was studied in 106 patients with bladder cancer diagnosed between 1994 and 1997. Immunohistochemistry was performed using a monoclonal antibody against Tn-C. RFS and OS were estimated by the Kaplan-Meier method and compared by the log rank test in univariate analysis and by the Cox multistep regression method in multivariate analysis.

RESULTS

Within the mean follow up period of 126 months, patients with diffuse Tn-C staining in the tumour stroma had a significantly worse OS than those with negative staining or only moderate Tn-C expression (p = 0.025). Patients with cytoplasmic expression of Tn-C had a significantly better OS than those without (p = 0.001). Multivariate analysis, taking into consideration age, grade, stage, tumour associated carcinoma in situ, progression, and Tn-C staining in tumour stroma, showed that only expression of Tn-C in invasive tumour cells was an independent positive prognostic factor for OS (p = 0.049).

CONCLUSIONS

Tn-C may provide important prognostic information in bladder cancer depending on the expression pattern in the tumour stroma or cytoplasm of the tumour cells.

Enhanced tenascin-C expression and matrix deposition during Ras/TGF-beta-induced progression of mammary tumor cells

Overexpression of tenascin-C (TN-C) in breast carcinomas has been associated with a migratory or even invasive tumor cell phenotype. The mechanisms regulating expression and matrix deposition of TN-C in normal and cancerous breast tissues are, however, little understood. Here, we demonstrate that mouse mammary epithelial cells (EpH4) transformed by oncogenic Ha-Ras (EpRas) overexpress TN-C, which accumulates in the cytoplasm. When EpRas cells undergo epithelial-mesenchymal transition (EMT) in response to TGFbeta1, they secrete TN-C into the culture medium. In EpRas cells undergoing TGFbeta1-induced EMT in three-dimensional (3D)-collagen gel cultures, TN-C was deposited into an extracellular matrix (ECM) already containing fibronectin and perlecan. Under less physiological 2D plastic cultures, EpRas cells undergoing EMT failed to deposit TN-C into an (apparently incomplete) ECM. Ras-downstream signaling was dissected by pharmacological inhibitors and effector-specific Ras mutants (V12S35, V12C40), specifically inhibiting or activating ERK/MAPK or PI3K signaling, respectively. We showed that TN-C overexpression required a hyperactive ERK/MAPK-signaling pathway, while elevated PI3K signaling did not enhance TN-C expression. Similarly, tumors induced by cells exhibiting hyperactive ERK/MAPK signaling showed expression of TN-C in the tumor cells themselves, while only endothelial cells expressed TN-C in tumors caused by the V12C40 mutant (incapable of EMT in vivo). Taken together, our data indicate that hyperactive ERK/MAPK signaling causes enhanced expression of TN-C, while its secretion is induced by TGFbeta1 and both signals cooperate in TN-C matrix deposition. Importantly, both signals also cooperate to induce EMT in vitro and tumor progression/metastasis in vivo.