Potential oncogenic action of tenascin-C in tumorigenesis

Extracellular matrix of glioblastoma inhibits polarization and transmigration of T cells: the role of tenascin-C in immune suppression

Dense accumulations of T cells are often found in peritumoral areas, which reduce the efficiency of contact-dependent lysis of tumor cells. We demonstrate in this study that the extracellular matrix (ECM) produced by tumors can directly regulate T cell migration. The transmigration rate of several T cells including peripheral blood primary T cell, Jurkat, and Molt-4 measured for glioma cells or glioma ECM was consistently low. Jurkat cells showed reduced amoeba-like shape formation and delayed ERK activation when they were in contact with monolayers or ECM of glioma cells as compared with those in contact with HepG2 and MCF-7 cells. Phospho-ERK was located at the leading edge of migrating Jurkat cells. Glioma cells, but not MCF-7 and HepG2 cells, expressed tenascin-C. Knocking down the tenascin-C gene using the short hairpin RNA strategy converted glioma cells to a transmigration-permissive phenotype for Jurkat cells regarding ERK activation, transmigration, and amoeba-like shape formation. In addition, exogenous tenascin-C protein reduced the amoeba-like shape formation and transmigration of Jurkat cells through MCF-7 and HepG2 cell monolayers. A high level of tenascin-C was visualized immunohistochemically in glioma tumor tissues. CD3(+) T cells were detected in the boundary tumor area and stained strongly positive for tenascin-C. In summary, glioma cells can actively paralyze T cell migration by the expression of tenascin-C, representing a novel immune suppressive mechanism achieved through tumor ECM.

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.

Tenascin-W is a specific marker of glioma-associated blood vessels and stimulates angiogenesis in vitro

The microenvironment hosting a tumor actively participates in regulating tumor cell proliferation, migration, and invasion. Among the extracellular matrix proteins enriched in the stroma of carcinomas are the tenascin family members tenascin-C and tenascin-W. Whereas tenascin-C overexpression in gliomas is known to correlate with poor prognosis, the status of tenascin-W in brain tumors has not been investigated so far. In the present study, we analyzed protein levels of tenascin-W in 38 human gliomas and found expression of tenascin-W in 80% of the tumor samples, whereas no tenascin-W could be detected in control, nontumoral brain tissues. Double immunohistochemical staining of tenascin-W and von Willebrand factor revealed that tenascin-W is localized around blood vessels, exclusively in tumor samples. In vitro, the presence of tenascin-W increased the proportion of elongated human umbilical vein endothelial cells (HUVECs) and augmented the mean speed of cell migration. Furthermore, tenascin-W triggered sprouting of HUVEC spheroids to a similar extent as the proangiogenic factor tenascin-C. In conclusion, our study identifies tenascin-W as a candidate biomarker for brain tumor angiogenesis that could be used as a molecular target for therapy irrespective of the glioma subtype.—Martina, E., Degen, M., Rüegg, C., Merlo, A., Lino, M. M., Chiquet-Ehrismann, R., Brellier, F. Tenascin-W is a specific marker of glioma-associated blood vessels and stimulates angiogenesis in vitro.

The role of tenascin-C in tissue injury and tumorigenesis

The extracellular matrix molecule tenascin-C is highly expressed during embryonic development, tissue repair and in pathological situations such as chronic inflammation and cancer. Tenascin-C interacts with several other extracellular matrix molecules and cell-surface receptors, thus affecting tissue architecture, tissue resilience and cell responses. Tenascin-C modulates cell migration, proliferation and cellular signaling through induction of pro-inflammatory cytokines and oncogenic signaling molecules amongst other mechanisms. Given the causal role of inflammation in cancer progression, common mechanisms might be controlled by tenascin-C during both events. Drugs targeting the expression or function of tenascin-C or the tenascin-C protein itself are currently being developed and some drugs have already reached advanced clinical trials. This generates hope that increased knowledge about tenascin-C will further improve management of diseases with high tenascin-C expression such as chronic inflammation, heart failure, artheriosclerosis and cancer.

The role of tenascin-C in tissue injury and tumorigenesis

The extracellular matrix molecule tenascin-C is highly expressed during embryonic development, tissue repair and in pathological situations such as chronic inflammation and cancer. Tenascin-C interacts with several other extracellular matrix molecules and cell-surface receptors, thus affecting tissue architecture, tissue resilience and cell responses. Tenascin-C modulates cell migration, proliferation and cellular signaling through induction of pro-inflammatory cytokines and oncogenic signaling molecules amongst other mechanisms. Given the causal role of inflammation in cancer progression, common mechanisms might be controlled by tenascin-C during both events. Drugs targeting the expression or function of tenascin-C or the tenascin-C protein itself are currently being developed and some drugs have already reached advanced clinical trials. This generates hope that increased knowledge about tenascin-C will further improve management of diseases with high tenascin-C expression such as chronic inflammation, heart failure, artheriosclerosis and cancer.

Systems-level modeling of cancer-fibroblast interaction

Cancer cells interact with surrounding stromal fibroblasts during tumorigenesis, but the complex molecular rules that govern these interactions remain poorly understood thus hindering the development of therapeutic strategies to target cancer stroma. We have taken a mathematical approach to begin defining these rules by performing the first large-scale quantitative analysis of fibroblast effects on cancer cell proliferation across more than four hundred heterotypic cell line pairings. Systems-level modeling of this complex dataset using singular value decomposition revealed that normal tissue fibroblasts variably express at least two functionally distinct activities, one which reflects transcriptional programs associated with activated mesenchymal cells, that act either coordinately or at cross-purposes to modulate cancer cell proliferation. These findings suggest that quantitative approaches may prove useful for identifying organizational principles that govern complex heterotypic cell-cell interactions in cancer and other contexts.

Tenascin-C is an endogenous activator of Toll-like receptor 4 that is essential for maintaining inflammation in arthritic joint disease

Although there have been major advances in the treatment of rheumatoid arthritis with the advent of biological agents, the mechanisms that drive cytokine production and sustain disease chronicity remain unknown. Tenascin-C (encoded by Tnc) is an extracellular matrix glycoprotein specifically expressed at areas of inflammation and tissue damage in inflamed rheumatoid joints. Here we show that mice that do not express tenascin-C show rapid resolution of acute joint inflammation and are protected from erosive arthritis. Intra-articular injection of tenascin-C promotes joint inflammation in vivo in mice, and addition of exogenous tenascin-C induces cytokine synthesis in explant cultures from inflamed synovia of individuals with rheumatoid arthritis. Moreover, in human macrophages and fibroblasts from synovia of individuals with rheumatoid arthritis, tenascin-C induces synthesis of proinflammatory cytokines via activation of Toll-like receptor 4 (TLR4). Thus, we have identified tenascin-C as a novel endogenous activator of TLR4-mediated immunity that mediates persistent synovial inflammation and tissue destruction in arthritic joint disease.

Tenascins and their implications in diseases and tissue mechanics

Tenascins are glycoproteins found in the extracellular matrix (ECM) of many tissues. Their role is not only to support the tissue structurally but also to regulate the fate of the different cell types populating the ECM. For instance, tenascins are required when active tissue modeling during embryogenesis or re-modeling after injury occurs. Interestingly, the four members of the tenascin family, tenascin-C, -X, -R and -W, show different and often mutually exclusive expression patterns. As a consequence, these structurally related proteins display distinct functions and are associated with distinct pathologies. The present review aims at presenting the four members of the tenascin family with respect to their structure, expression patterns and implications in diseases and tissue mechanics.

Immunohistochemical distribution of basement membrane proteins in the human inner ear from older subjects

The immunolocalization of several basement membrane (BM) proteins was investigated in vestibular endorgans microdissected from temporal bones obtained from subjects with a documented normal auditory and vestibular function (n=5, average age=88 years old). Fluorescent immunostaining using antibodies directed at collagen IV alpha 2, nidogen-1, laminin-beta2, alpha-dystroglycan, and tenascin-C was applied to cryosections from human cochlea, cristae ampullares, utricular and saccular maculae. Collagen IV alpha 2, nidogen-1, and laminin-beta2 localized to all subepithelial cochlear BMs, Reissner's membrane, strial and spiral ligamental perineural and perivascular BMs, and the spiral limbus. Tenascin-C localized to the basilar membrane and the osseous spiral lamina. alpha-Dystroglycan localized to most cochlear BMs except those in the spiral ligament, basilar membrane and spiral limbus. Collagen IV, nidogen-1, and laminin-beta2 localized to the subepithelial BMs of the maculae and cristae ampullares, and the perineural and perivascular BMs within the underlying stroma. The BM underlying the transitional and dark cell region of the cristae ampullares also expressed collagen IV, nidogen-1, and laminin-beta2. Tenascin-C localized to the subepithelial BMs of the utricular maculae and cristae ampullares, and to calyx-like profiles throughout the vestibular epithelium, but not to the perineural and perivascular BMs. alpha-Dystroglycan colocalized with aquaporin-4 in the basal vestibular supporting cell, and was also expressed in the subepithelial BMs, as well as perivascular and perineural BMs. This study provides the first comprehensive immunolocalization of these ECM proteins in the human inner ear. The validity of the rodent models for inner ear disorders secondary to BM pathologies was confirmed as there is a high degree of conservation of expression of these proteins in the human inner ear. This information is critical to begin to unravel the role that BMs may play in human inner ear physiology and audiovestibular pathologies.

Prognostic molecular markers in cholangiocarcinoma: a systematic review

The worldwide incidence of cholangiocarcinoma (CC) is steadily rising, with the incidence in United Kingdom (UK) now exceeding 1000 cases per year. It is an aggressive malignancy typified by unresponsiveness to the existing chemotherapy and radiotherapy regimes in the vast majority of cases. Surgery offers the only hope of a cure, though post-operative disease recurrence is common, with 5-year survival rates of less than 25% following resection. Developments in molecular techniques and improved understanding of the basis of carcinogenesis in CC has led to examination of the role of biomarkers in predicting poor outcome. This systematic review examines published evidence relating to the prognostic significance of these molecular markers in CC. Of the molecular markers which have been investigated to date, p53 mutation, cyclins, proliferation indices, mucins, CA19-9, CRP and aneuploidy appear to hold significant potential as predictors of outcome in CC. These and other biomarkers may themselves represent novel therapeutic targets for CC.

Combined lysophosphatidic acid/platelet-derived growth factor signaling triggers glioma cell migration in a tenascin-C microenvironment

The antiadhesive extracellular matrix molecule tenascin-C abrogates cell spreading on fibronectin through competitive inhibition of syndecan-4, thereby preventing focal adhesion kinase (FAK) activation and triggering enhanced proteolytic degradation of both RhoA and tropomyosin 1 (TM1). Here, we show that simultaneous signaling by lysophosphatidic acid (LPA) and platelet-derived growth factor (PDGF) initiates glioma cell spreading and migration through syndecan-4-independent activation of paxillin and FAK and by stabilizing expression of RhoA, TM1, TM2, and TM3. By using gene silencing methods, we show that paxillin, TM1, TM2, and TM3 are essential for LPA/PDGF-induced cell spreading on a fibronectin/tenascin-C (FN/TN) substratum. LPA/PDGF-induced cell spreading and migration on FN/TN depends on phosphatidylinositol 3-kinase, RhoKinase, and mitogen-activated protein kinase/extracellular signal-regulated kinase kinase 1/2 but is independent of phospholipase C and Jun kinase. RNA microarray data reveal expression of tenascin-C, PDGFs, LPA, and the respective receptors in several types of cancer, suggesting that the TN/LPA/PDGF axis exists in malignant tumors. These findings may in turn be relevant for diagnostic or therapeutic applications targeting cancer.

Identification of glycoproteins from mouse skin tumors and plasma

Plasma has been the focus of testing different proteomic technologies for the identification of biomarkers due to its ready accessibility. However, it is not clear if direct proteomic analysis of plasma can be used to discover new marker proteins from tumor that are associated with tumor progression. Here, we reported that such proteins can be detected in plasma in a chemical induced skin cancer mouse model. We analyzed glycoproteins from both benign papillomas and malignant carcinomas from mice using our recently developed platform, solid-phase extraction of glycopeptides (SPEG) and mass spectrometry, and identified 463 unique N-linked glycosites from 318 unique glycoproteins. These include most known extracellular proteins that have been reported to play roles in skin cancer development such as thrombospondin, cathepsins, epidermal growth factor receptor, cell adhesion molecules, cadherins, integrins, tuberin, fibulin, TGFβ receptor, etc. We further investigated whether these tumor proteins could be detected in plasma from tumor bearing mice using isotope labeling and 2D-LC-MALDI-MS/MS. Two tumor glycoproteins, Tenascin-C and Arylsulfatase B, were identified and quantified successfully in plasma from tumor bearing mice. This result indicates that analysis of tumor associated proteins in tumors and plasma by method using glycopeptide capture, isotopic labeling, and mass spectrometry can be used as a discovery tool to identify candidate tumor proteins that may be detected in plasma.

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.

Secretion of collagen I and tenascin is modulated by laminin-111 in 3D culture of human adenoid cystic carcinoma cells

Adenoid cystic carcinoma is a frequent malignant salivary gland neoplasm with high levels of recurrence and metastasis. This neoplasm expresses prominent extracellular matrix (ECM). We are studying regulatory mechanisms underlying secretion of ECM molecules in adenoid cystic carcinoma. We have previously demonstrated that laminin modulates the phenotype of a human adenoid cystic carcinoma (CAC2) cell line. Thus, this molecule would be a good candidate to regulate secretion of ECM molecules in these cells. Here we analysed the role played by laminin-111 [formerly laminin-1; Aumailley et al. (2005). Matrix Biol. 24, 326] stimulating secretory activity of CAC2 cells. Three-dimensional cultures of cells in laminin-111 (treated) or agarose (controls) were studied by light and electron microscopy. Ultrastructural analysis of CAC2 cells grown within laminin-111 showed pseudocysts filled with secretory-like material. Cells exhibited prominent and dilated endoplasmic reticulum and coated and uncoated vesicles. Ultrastructural findings suggested that laminin-111 induced secretory activity in CAC2 cells. We further investigated this point by light microscopy, immunofluorescence and confocal microscopy. Histochemistry showed periodic acid-Schiff (PAS)-positive diastase-resistant material in CAC2 cells treated by laminin-111. This material could represent laminin-induced secretion of ECM molecules. We searched for collagen I and tenascin in CAC2 cells treated by laminin-111. Confocal microscopy and immunoblot showed that laminin-111 enhanced secretion of collagen I and tenascin in CAC2 cells. We suggest that laminin-111 modulates secretion of collagen I and tenascin in cells derived from human adenoid cystic carcinoma.

Tenascin and fibronectin expression in carcinoma ex pleomorphic adenoma

This study was conducted to analyze the participation of tenascin and fibronectin, components of the extracellular matrix, in different types of carcinoma ex pleomorphic adenoma (CXPA). Seventeen cases of CXPA, classified according to the presence of epithelial and myoepithelial cells and the degree of invasion-intracapsular, minimally, and frankly invasive carcinoma-were immunohistochemically labeled for tenascin and fibronectin. Normal salivary gland included in the specimens showed tenascin only around the excretory duct, and fibronectin slightly expressed all over the stroma of the gland. In reminiscent pleomorphic adenoma, tenascin and fibronectin were observed around tubular structures and in the stroma. Both tenascin and fibronectin were expressed in all the CXPA studied. In areas of in situ carcinoma of the intracapsular type, the expression of these extracellular matrix proteins was enhanced compared with areas of residual pleomorphic adenoma. In intracapsular and minimally invasive types of CXPA, some areas of the tumor border presented tenascin and no fibronectin, pattern that may represent the real invasive front. In frankly invasive CXPA type with only epithelial component, fibronectin was strongly observed in a fibrillar network pattern, and tenascin was only focal. In frankly invasive type with myoepithelial component, tenascin staining was very strong and diffuse. This study showed different patterns of expression of tenascin and fibronectin along the process of tumorigenesis and tumor progression in CXPA, a fact that might play a role in invasion properties of these tumors.

Breast tumor microenvironment: proteomics highlights the treatments targeting secretome

Tumor secreted substances (secretome), including extracellular matrix (ECM) components, act as mediators of tumor-host communication in the breast tumor microenvironment. Proteomic analysis has emphasized the value of the secretome as a source of prospective markers and drug targets for the treatment of breast cancers. Utilizing bioinformatics, our recent studies revealed global changes in protein expression after the activation of ECM-mediated signaling in breast cancer cells. A newly designed technique integrating a capillary ultrafiltration (CUF) probe with mass spectrometry was demonstrated to dynamically sample and identify in vivo and pure secretome from the tumor microenvironment. Such in vivo profiling of breast cancer secretomes may facilitate the development of novel drugs specifically targeting secretome.

Tenascin-C expression and its prognostic significance in colorectal cancer

OBJECTIVE

The extracellular matrix glycoprotein tenascin-C has been proposed as a tumor marker with prognostic significance in many cancer forms, but in colorectal cancer, reported results have been controversial. The aim of this study was to evaluate the prognostic value of immunohistochemical tenascin-C expression in a series of 231 patients with colorectal cancer.

METHODS

Paraffin-embedded formalin-fixed specimens were stained with a tenascin-C-specific monoclonal antibody, and the stromal staining intensity and pattern were analyzed.

RESULTS

Tenascin-C immunoreactivity was observed in all 231 specimens, with a pattern of staining that was diffuse and interstitial. The staining was occasional in 39 (17%), moderate in 106 (46%) and strong in 86 specimens (37%). There was no statistically significant association between tenascin-C immunoreactivity and any of the other clinicopathological variables. The cumulative 5-year survival rates of patients with occasional and weak staining were similar (56.8 and 54.9%, respectively), while the patients with strong tenascin-C staining had a lower survival rate (46.1%). This difference in survival was not significant (p = 0.23). The staining pattern and distribution can be viewed from digitized representative microscope slides (virtual slides) at http://www.webmicroscope.net/supplements/tenascin.

CONCLUSIONS

Our results indicate that immunohistochemical expression of tenascin-C is not of prognostic significance in colorectal cancer.

Downregulation of several fibulin genes in prostate cancer

BACKGROUND

Fibulins, encoded by FBLN genes, are extracellular matrix proteins influencing cell adhesion and migration. Altered expression of fibulins is associated with progression of several cancer types, but has not been studied in prostate cancer.

METHODS

Expression of FBLN1 (major splice forms C and D), FBLN4, FBLN5, SPOCK1, and TENC was compared between 47 prostate cancer samples and 13 benign prostatic tissues by quantitative RT-PCR. Fibulin-1 and fibulin-5 expression was studied by immunohistochemistry. Effects of androgens and the DNA methylation inhibitor 5-aza-2'-deoxycytidine on fibulin expression were investigated in different prostate cancer cell lines.

RESULTS

Our recent microarray analysis suggested downregulation of three fibulins, FBLN1, FBLN4, and FBLN5, in prostate cancer, while two further ECM genes, SPOCK1 (testican) and TENC (tenascin C), appeared upregulated or unchanged. These observations were corroborated by quantitative RT-PCR. Accordingly, FBLN1 and FBLN4 were weakly expressed in carcinoma lines compared to normal prostate epithelial cells (PrECs). Only FBLN4 was induced by 5-aza-2'-deoxycytidine, but its promoter was unmethylated. Androgen did not affect expression of FBLN genes. The FBLN1C and FBLN1D splice forms were coordinately expressed. Fibulin-1 protein was weakly detectable in benign PrECs, but tended to accumulate in cancer cells. Fibulin-5 was predominantly located in the stroma with a strong gradient from the periurethral to the peripheral zone, and lost in cancers.

CONCLUSIONS

Three FBLN genes are significantly downregulated in prostate cancer, whereas SPOCK1 is often upregulated. FBLN5 downregulation fits its postulated anticancerous function, whereas FBLN1 and FBLN4 behave different than in certain other cancers.

Avian tenascin-W: expression in smooth muscle and bone, and effects on calvarial cell spreading and adhesion in vitro

Tenascins are glycoproteins found primarily in the embryonic extracellular matrix. Here we have characterized the fourth and final member of the tenascin family in birds: tenascin-W. Avian tenascin-W has 3.5 epidermal growth factor-like repeats, 6 fibronectin type III domains, and a C-terminal fibrinogen-related domain. Immunohistochemistry reveals that avian tenascin-W is expressed transiently in developing smooth muscle, tendons, and ligaments, but the primary site of tenascin-W expression during development is in the extracellular matrix of bone and the cellular periosteum. In bony matrix, tenascin-W-coated fibrils partly overlap with fibrils that contain tenascin-C. The anti-tenascin-W also labels fibrils in cultures of osteogenic embryonic chicken calvarial cells. Primary calvarial cells cultured on purified tenascin-W become rounded, and fewer of these cells spread on fibronectin when tenascin-W is added to the medium when compared with calvarial cells cultured on fibronectin alone. Moreover, tenascin-W reduces the adhesion of calvarial cells to collagen type I in a shear force assay. We conclude that tenascin-W is likely to play a phylogenetically conserved role in developing bone and that it shares some of the basic anti-adhesive and matrix modulatory properties as tenascin-C.

Tenascin-W is a novel marker for activated tumor stroma in low-grade human breast cancer and influences cell behavior

This is the first report about human tenascin-W, the fourth and final member of the extracellular matrix protein family of tenascins. Sixty-three human breast tumor extracts were analyzed by Western blotting for the presence of tenascin-W and compared with tenascin-C, an established marker of tumor stroma. Interestingly, we found tenascin-W expression in the majority of the tumor tissues, but no detectable expression in the normal mammary parenchyma. Eighty-one percent of the breast tumor samples were tenascin-W positive and 86% showed expression of tenascin-C. However, tenascin-W and tenascin-C amounts varied greatly between tumors and some contained either tenascin-W or tenascin-C exclusively, indicating independent mechanisms regulating their expression. Although there was no difference between high- or low-grade tumors with respect to the presence of tenascin-C, tenascin-W was more prominent in low-grade tumors. For 42 of the breast cancer tissues, a frozen tumor microarray was available to confirm the Western blot data by immunohistochemistry. Similar to tenascin-C, tenascin-W was detected in the tumor stroma. Fibroblasts adhered to tenascin-W in a beta(1) integrin-dependent manner and spread with a distinctive morphology under conditions where they remained round on tenascin-C. CHOB2 cells expressing alpha(v)beta(1) or alpha4beta(1) integrins were able to spread on tenascin-W. Furthermore, addition of tenascin-W to the culture medium increased migration of breast cancer cells toward a fibronectin substratum in vitro. These data imply that tenascin-W expression in the activated tumor stroma facilitates tumorigenesis by supporting the migratory behavior of breast cancer cells.

Endothelin receptor type B counteracts tenascin-C-induced endothelin receptor type A-dependent focal adhesion and actin stress fiber disorganization

Tenascin-C, an extracellular matrix molecule of the tumor-specific microenvironment, counteracts the tumor cell proliferation-suppressing effect of fibronectin by blocking the integrin alpha(5)beta(1)/syndecan-4 complex. This causes cell rounding and stimulates tumor cell proliferation. Tenascin-C also stimulates endothelin receptor type A (EDNRA) expression. Here, we investigated whether signaling through endothelin receptors affects tenascin-C-induced cell rounding. We observed that endothelin receptor type B (EDNRB) activation inhibited cell rounding by tenascin-C and induced spreading by restoring expression and function of focal adhesion kinase (FAK), paxillin, RhoA, and tropomyosin-1 (TM1) via activation of epidermal growth factor receptor, phospholipase C, c-Jun NH(2)-terminal kinase, and the phosphatidylinositol 3-kinase pathway. In contrast to EDNRB, signaling through EDNRA induced cell rounding, which correlated with FAK inhibition and TM1 and RhoA protein destabilization in the presence of tenascin-C. This occurred in a mitogen-activated protein kinase/extracellular signal-regulated kinase kinase-dependent manner. Thus, tumorigenesis might be enhanced by tenascin-C involving EDNRA signaling. Inhibition of tenascin-C in combination with blocking both endothelin receptors could present a strategy for sensitization of cancer and endothelial cells toward anoikis.

Constitutively activated Stat3 induces tumorigenesis and enhances cell motility of prostate epithelial cells through integrin beta 6

The persistent activation of signal transducer and activator of transcription 3 (Stat3) is a common feature of prostate cancer. However, little is known about the Stat3 targets that may mediate prostate tumorigenesis. The introduction of an activating mutant form of Stat3 (Stat3-C) into immortalized prostate epithelial cells resulted in tumorigenesis. Stat3-C-expressing cells had decreased E-cadherin levels, increased numbers of lamellipodia and stress fibers, and enhanced migratory capacities compared to vector control-expressing cells, with a concomitant increase in the expression of integrin beta6 and its ligand, fibronectin (FN). Exogenously added FN increased cellular migration, with a concomitant loss of E-cadherin expression. The blockade of integrin alphavbeta6 in Stat3-C-expressing cells inhibited migration, increased E-cadherin levels, and reduced colony formation in soft agar. These results demonstrate the sufficiency of constitutively activated Stat3 in mediating prostate tumorigenesis and identify novel Stat3 targets that are involved in promoting cell migration and transformation.

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.

Identification of tumor-specific molecular signatures in intracranial ependymoma and association with clinical characteristics

PURPOSE

To delineate clinically relevant molecular signatures of intracranial ependymoma.

MATERIALS AND METHODS

We analyzed 24 primary intracranial ependymomas. For genomic profiling, microarray-based comparative genomic hybridization (CGH) was used and results were validated by fluorescent in situ hybridization and loss of heterozygosity mapping. We performed gene expression profiling using microarrays, real-time quantitative reverse transcriptase polymerase chain reaction, and methylation analysis of selected genes. We applied class comparison analyses to compare both genomic and expression profiling data with clinical characteristics.

RESULTS

A variable number of genomic imbalances were detected by array CGH, revealing multiple regions of recurrent gain (including 2q23, 7p21, 12p, 13q21.1, and 20p12) and loss (including 5q31, 6q26, 7q36, 15q21.1, 16q24, 17p13.3, 19p13.2, and 22q13.3). An ependymoma-specific gene expression signature was characterized by the concurrent abnormal expression of developmental and differentiation pathways, including NOTCH and sonic hedgehog signaling. We identified specific differentially imbalanced genomic clones and gene expression signatures significantly associated with tumor location, patient age at disease onset, and retrospective risk for relapse. Integrated genomic and expression profiling allowed us to identify genes of which the expression is deregulated in intracranial ependymoma, such as overexpression of the putative proto-oncogene YAP1 (located at 11q22) and downregulation of the SULT4A1 gene (at 22q13.3).

CONCLUSION

The present exploratory molecular profiling study allowed us to refine previously reported intervals of genomic imbalance, to identify novel restricted regions of gain and loss, and to identify molecular signatures correlating with various clinical variables. Validation of these results on independent data sets represents the next step before translation into the clinical setting.

Myofibroblastic stromal reaction and expression of tenascin-C and laminin in prostate adenocarcinoma

The aim of this study was to analyse relationship between changes of the stroma and expression of tenascin-C (TN-C) and laminin in prostate carcinoma. Tenascin-C immunostaining was increased, and laminin decreased in carcinomas compared with peritumoral tissue and benign prostate hyperplasia (P<0.05). Statistical analysis confirmed connection between stromal changes and TN-C expression in prostate carcinoma (P<0.05). Gleason pattern 3 carcinomas showed more pronounced stromal reaction and TN-C expression compared with Gleason pattern 4 carcinomas (P<0.05). The main cells in prostate cancer stroma are myofibroblasts that are also responsible for tenascin production. Degradation of laminin was not connected with myofibroblastic stromal changes.

Capturing complex 3D tissue physiology in vitro

The emergence of tissue engineering raises new possibilities for the study of complex physiological and pathophysiological processes in vitro. Many tools are now available to create 3D tissue models in vitro, but the blueprints for what to make have been slower to arrive. We discuss here some of the 'design principles' for recreating the interwoven set of biochemical and mechanical cues in the cellular microenvironment, and the methods for implementing them. We emphasize applications that involve epithelial tissues for which 3D models could explain mechanisms of disease or aid in drug development.

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.