Focal adhesion integrity is downregulated by the alternatively spliced domain of human tenascin

Thrombospondin-1 Signaling Through the Calreticulin/LDL Receptor Related Protein 1 Axis: Functions and Possible Roles in Glaucoma

Thrombospondin-1 (TSP-1) is a matricellular extracellular matrix protein. Matricellular proteins are components of the extracellular matrix (ECM) that regulate key cellular functions and impact ECM organization, but which lack direct primary structural roles in the ECM. TSP-1 expression is upregulated in response to injury, hypoxia, growth factor stimulation, inflammation, glucose, and by reactive oxygen species. Relevant to glaucoma, TSP-1 is also a mechanosensitive molecule upregulated by mechanical stretch. TSP-1 expression is increased in ocular remodeling in glaucoma in both the trabecular meshwork and in the optic nerve head. The exact roles of TSP-1 in glaucoma remain to be defined, however. It plays important roles in cell behavior and in ECM remodeling during wound healing, fibrosis, angiogenesis, and in tumorigenesis and metastasis. At the cellular level, TSP-1 can modulate cell adhesion and migration, protease activity, growth factor activity, anoikis resistance, apoptosis, and collagen secretion and matrix assembly and cross-linking. These multiple functions and macromolecular and receptor interactions have been ascribed to specific domains of the TSP-1 molecule. In this review, we will focus on the cell regulatory activities of the TSP-1 N-terminal domain (NTD) sequence that binds to cell surface calreticulin (Calr) and which regulates cell functions via signaling through Calr complexed with LDL receptor related protein 1 (LRP1). We will describe TSP-1 actions mediated through the Calr/LRP1 complex in regulating focal adhesion disassembly and cytoskeletal reorganization, cell motility, anoikis resistance, and induction of collagen secretion and matrix deposition. Finally, we will consider the relevance of these TSP-1 functions to the pathologic remodeling of the ECM in glaucoma.

Tenascin-C promotes bladder cancer progression and its action depends on syndecan-4 and involves NF-κB signaling activation

Background

Bladder Cancer (BCa) is a severe genitourinary tract disease with an uncertain pathology. Increasing evidence indicates that the tumor microenvironment plays a decisive role with respect to cancer progression, and that this is driven by tumor cell interactions with stromal components. Tenascin-C (TN-C) is an important extracellular matrix (ECM) component, which has been reported to be involved in other types of cancer, such as breast cancer. The expression of TN-C in BCa tissue has been reported to be positively associated with the BCa pathological grade, yet the presence of urine TN-C is considered as an independent risk factor for BCa. However, the role of TN-C in BCa progression is still unknow. Thus, the object of the present investigation is to determine the role of TN-C in BCa progression and the involved mechanism.

Methods

In this study, expression of TN-C in BCa tissue of Chinese local people was determined by IHC. Patients corresponding to tumor specimens were flowed up by telephone call to get their prognostic data and analyzed by using SPSS 19.0 statistic package. In vitro mechanistic investigation was demonstrated by QT-qPCR, Western Blot, Plasmid transfection to establishment of high/low TN-C-expression stable cell line, Boyden Chamber Assay, BrdU incorporation, Wound Healing, laser scanning confocal microscopy (LSCM) and ELISA.

Results

TN-C expression in BCa tissue increases with tumor grade and is an independent risk factor for BCa patient. The in vitro investigation suggested that TN-C enhances BCa cell migration, invasion, proliferation and contributes to the elevated expression of EMT-related markers by activating NF-κB signaling, the mechanism of which involving in syndecan-4.

Conclusions

Expression of TN-C in BCa tissues of Chinese local people is increased according to tumor grade and is an independent risk factor. TN-C mediates BCa cell malignant behavior via syndecan-4 and NF-κB signaling. Although the mechanisms through which syndecan-4 is associated with the activation of NF-κB signaling are unclear, the data presented herein provide a foundation for future investigations into the role of TN-C in BCa progression.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09285-x.

Elevated glucose alters global gene expression and tenascin-C alternative splicing in mesangial cells

Mesangial cells are the major extracellular matrix (ECM)-producing cells in the kidney glomerulus and, when exposed to elevated glucose levels, they up-regulate assembly of fibronectin (FN) and other ECM proteins. Increases in glucose concentration are known to alter gene expression; here we investigated the connection between increased ECM production and changes in gene expression in mesangial cells. Comparison of mesangial cells grown in normal or high glucose conditions by RNA-sequencing showed significant expression changes in over 6000 genes and, when grouped by KEGG pathway analysis, identified the ECM-receptor interaction and focal adhesion pathways among the top 5 upregulated pathways. Of note was the significant increase in expression of tenascin-C (TN-C), a known regulator of FN matrix assembly. Mouse TN-C has multiple isoforms due to alternative splicing of 6 FNIII repeat exons. In addition to the transcriptional increase with high glucose, exon inclusion via alternative splicing was also changed resulting in production of higher molecular weight isoforms of TN-C. Mesangial cells grown in normal glucose secreted small isoforms with 1–2 variable repeats included whereas in high glucose large isoforms estimated to include 5 repeats were secreted. Unlike the smaller isoforms, the larger TN-C was not detected in the FN matrix. This change in TN-C isoforms may affect the regulation of FN matrix assembly and in this way may contribute to increased ECM accumulation under high glucose conditions.

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Elevated glucose alters gene expression in cultured mesangial cells.

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RNA-sequencing identifies increased expression of ECM proteins and receptors.

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High glucose changes tenascin-C isoform expression by alternative splicing.

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Differential ECM localization is detected for large vs small tenascin-C isoforms.

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Switch in tenascin-C may contribute to ECM accumulation in the diabetic glomerulus.

Prostate cancer extracellular vesicles mediate intercellular communication with bone marrow cells and promote metastasis in a cholesterol-dependent manner

Primary tumours can establish long-range communication with distant organs to transform them into fertile soil for circulating tumour cells to implant and proliferate, a process called pre-metastatic niche (PMN) formation. Tumour-derived extracellular vesicles (EV) are potent mediators of PMN formation due to their diverse complement of pro-malignant molecular cargo and their propensity to target specific cell types (Costa-Silva et al., 2015; Hoshino et al., 2015; Peinado et al., 2012; Peinado et al., 2017). While significant progress has been made to understand the mechanisms by which pro-metastatic EVs create tumour-favouring microenvironments at pre-metastatic organ sites, comparatively little attention has been paid to the factors intrinsic to recipient cells that may modify the extent to which pro-metastatic EV signalling is received and transduced. Here, we investigated the role of recipient cell cholesterol homeostasis in prostate cancer (PCa) EV-mediated signalling and metastasis. Using a bone metastatic model of enzalutamide-resistant PCa, we first characterized an axis of EV-mediated communication between PCa cells and bone marrow that is marked by in vitro and in vivo PCa EV uptake by bone marrow myeloid cells, activation of NF-κB signalling, enhanced osteoclast differentiation, and reduced myeloid thrombospondin-1 expression. We then employed a targeted, biomimetic approach to reduce myeloid cell cholesterol in vitro and in vivo prior to conditioning with PCa EVs. Reducing myeloid cell cholesterol prevented the uptake of PCa EVs by recipient myeloid cells, abolished NF-κB activity and osteoclast differentiation, stabilized thrombospondin-1 expression, and reduced metastatic burden by 77%. These results demonstrate that cholesterol homeostasis in bone marrow myeloid cells regulates pro-metastatic EV signalling and metastasis by acting as a gatekeeper for EV signal transduction.

Pleiotropic Role of Tenascin-C in Central Nervous System Diseases: From Basic to Clinical Applications

The extracellular matrix is composed of a variety of macromolecular substances secreted by cells, which form a complex network that supports and connects tissue structures, regulates the morphogenesis of tissues, and maintains the physiological activities of cells. Tenascin-C, a secreted extracellular matrix glycoprotein, is abundantly expressed after exposure to pathological stimuli. It plays an important regulatory role in brain tumors, vascular diseases, and neurodegenerative diseases by mediating inflammatory responses, inducing brain damage, and promoting cell proliferation, migration, and angiogenesis through multiple signaling pathways. Therefore, tenascin-C may become a potential therapeutic target for intracranial diseases. Here, we review and discuss the latest literature regarding tenascin-C, and we comprehensively explain the role and clinical significance of tenascin-C in intracranial diseases.

Down-regulation of tenascin-C inhibits breast cancer cells development by cell growth, migration, and adhesion impairment

Tenascin-C (TNC) is an extracellular matrix (ECM) glycoprotein that plays an important role in cell proliferation, migration, and tumour invasion in various cancers. TNC is one of the main protein overexpressed in breast cancer, indicating a role for this ECM molecule in cancer pathology. In this study we have evaluated the TNC loss-off-function in breast cancer cells. In our approach, we used dsRNA sharing sequence homology with TNC mRNA, called ATN-RNA. We present the data showing the effects of ATN-RNA in MDA-MB-231 cells both in monolayer and three-dimensional culture. Cells treated with ATN-RNA were analyzed for phenotypic alterations in proliferation, migration, adhesion, cell cycle, multi-caspase activation and the involvement in epithelial to mesenchymal transition (EMT) processes. As complementary analysis the oncogenomic portals were used to assess the clinical implication of TNC expression on breast cancer patient's survival, showing the TNC overexpression associated with a poor survival outcome. Our approach applied first in brain tumors and then in breast cancer cell lines reveals that ATN-RNA significantly diminishes the cell proliferation, migration and additionally, reverses the mesenchymal cells phenotype to the epithelial one. Thus, TNC could be considered as the universal target in different types of tumors, where TNC overexpression is associated with poor prognosis.

Tenascin-C Induces Phenotypic Changes in Fibroblasts to Myofibroblasts with High Contractility through the Integrin αvβ1/Transforming Growth Factor β/SMAD Signaling Axis in Human Breast Cancer

Tenascin-C (TNC) is strongly expressed by fibroblasts and cancer cells in breast cancer. To assess the effects of TNC on stromal formation, we examined phenotypic changes in human mammary fibroblasts treated with TNC. The addition of TNC significantly up-regulated α-smooth muscle actin (α-SMA) and calponin. TNC increased the number of α-SMA- and/or calponin-positive cells with well-developed stress fibers in immunofluorescence, which enhanced contractile ability in collagen gel contraction. The treatment with TNC also significantly up-regulated its own synthesis. Double immunofluorescence of human breast cancer tissues showed α-SMA- and/or calponin-positive myofibroblasts in the TNC-deposited stroma. Among several receptors for TNC, the protein levels of the αv and β1 integrin subunits were significantly increased after the treatment. Immunofluorescence showed the augmented colocalization of αv and β1 at focal adhesions. Immunoprecipitation using an anti-αv antibody revealed a significant increase in coprecipitated β1 with TNC in lysates. The knockdown of αv and β1 suppressed the up-regulation of α-SMA and calponin. The addition of TNC induced the phosphorylation of SMAD2/3, whereas SB-505124 and SIS3 blocked myofibroblast differentiation. Therefore, TNC enhances its own synthesis by forming a positive feedback loop and increases integrin αvβ1 heterodimer levels to activate transforming growth factor-β signaling, which is followed by a change to highly contractile myofibroblasts. TNC may essentially contribute to the stiffer stromal formation characteristic of breast cancer tissues.

Alternative splicing controls cell lineage-specific responses to endogenous innate immune triggers within the extracellular matrix

The identification of barely more than 20,000 human genes was amongst the most surprising outcomes of the human genome project. Alternative splicing provides an essential means of expanding the proteome, enabling a single gene to encode multiple, distinct isoforms by selective inclusion or exclusion of exons from mature mRNA. However, mis-regulation of this process is associated with most human diseases. Here, we examine the impact of post-transcriptional processing on extracellular matrix function, focusing on the complex alternative splicing patterns of tenascin-C, a molecule that can exist in as many as 500 different isoforms. We demonstrate that the pro-inflammatory activity of this endogenous innate immune trigger is controlled by inclusion or exclusion of a novel immunomodulatory site located within domains AD2AD1, identifying this as a mechanism that prevents unnecessary inflammation in healthy tissues but enables rapid immune cell mobilization and activation upon tissue damage, and defining how this goes awry in autoimmune disease.

The Tumor Microenvironment: Focus on Extracellular Matrix

The extracellular matrix (ECM) regulates the development and maintains tissue homeostasis. The ECM is composed of a complex network of molecules presenting distinct biochemical properties to regulate cell growth, survival, motility, and differentiation. Among their components, proteoglycans (PGs) are considered one of the main components of ECM. Its composition, biomechanics, and anisotropy are exquisitely tuned to reflect the physiological state of the tissue. The loss of ECM's homeostasis is seen as one of the hallmarks of cancer and, typically, defines transitional events in tumor progression and metastasis. In this chapter, we discuss the types of proteoglycans and their roles in cancer. It has been observed that the amount of some ECM components is increased, while others are decreased, depending on the type of tumor. However, both conditions corroborate with tumor progression and malignancy. Therefore, ECM components have an increasingly important role in carcinogenesis and this leads us to believe that their understanding may be a key in the discovery of new anti-tumor therapies. In this book, the main ECM components will be discussed in more detail in each chapter.

Matricellular Proteins: Functional Insights From Non-mammalian Animal Models

The extracellular matrix (ECM) has central roles in tissue integrity and remodeling throughout the life span of animals. While collagens are the most abundant structural components of ECM in most tissues, tissue-specific molecular complexity is contributed by ECM glycoproteins. The matricellular glycoproteins are categorized primarily according to functional criteria and represented predominantly by the thrombospondin, tenascin, SPARC/osteonectin, and CCN families. These proteins do not self-assemble into ECM fibrils; nevertheless, they shape ECM properties through interactions with structural ECM proteins, growth factors, and cells. Matricellular proteins also promote cell migration or morphological changes through adhesion-modulating or counter-adhesive actions on cell-ECM adhesions, intracellular signaling, and the actin cytoskeleton. Typically, matricellular proteins are most highly expressed during embryonic development. In adult tissues, expression is more limited unless activated by cues for dynamic tissue remodeling and cell motility, such as occur during inflammatory response and wound repair. Many insights in the complex roles of matricellular proteins have been obtained from studies of gene knockout mice. However, with the exception of chordate-specific tenascins, these are highly conserved proteins that are encoded in many animal phyla. This review will consider the increasing body of research on matricellular proteins in nonmammalian animal models. These models provide better access to the very earliest stages of embryonic development and opportunities to study biological processes such as limb and organ regeneration. In aggregate, this research is expanding concepts of the functions and mechanisms of action of matricellular proteins.

Hedgehog signaling stimulates Tenascin C to promote invasion of pancreatic ductal adenocarcinoma cells through Annexin A2

Pancreatic adenocarcinoma (PDA) is characterized by a dense desmoplastic reaction that comprises 60-90% of the tumor, while only 10-40% of the tumor is composed of malignant epithelial cells. This desmoplastic reaction is composed of stromal fibroblast cells, extracellular matrix proteins, and immune cells. Accumulating evidence has suggested that the stromal and epithelial cell compartments interact during the pathogenesis of this disease. Therefore, it is important to identify the signaling pathways responsible for this interaction to better understand the mechanisms by which PDA invades and metastasizes. Here, we show that secreted stromal factors induce invasion of PDA cells. Specifically, hedgehog signaling from the tumor cells induces tenascin C (TnC) secretion from the stromal cells that acts back upon the tumor cells in a paracrine fashion to induce the invasion of PDA cells through its' receptor annexin A2 (AnxA2). Therefore, blocking the interaction between TnC and AnxA2 has the potential to prevent liver metastasis in PDA.

Role of tenascin-C in articular cartilage

Tenascin-C (TN-C) is a glycoprotein component of the extracellular matrix (ECM). TN-C consists of four distinct domains, including the tenascin assembly domain, epidermal growth factor-like repeats, fibronectin type III-like repeats, and the fibrinogen-like globe (FBG) domain. This review summarizes the role of TN-C in articular cartilage. Expression of TN-C is associated with the development of articular cartilage but markedly decreases during maturation of chondrocytes and disappears almost completely in adult articular cartilage. Increased expression of TN-C has been found at diseased cartilage and synovial sites in osteoarthritis (OA) and rheumatoid arthritis (RA). TN-C is increased in the synovial fluid in patients with OA and RA. In addition, serum TN-C is elevated in RA patients. TN-C could be a useful biochemical marker for joint disease. The addition of TN-C results in different effects among TN-C domains. TN-C fragments might be endogenous inducers of cartilage matrix degradation; however, full-length TN-C could promote cartilage repair and prevent cartilage degeneration. The deficiency of TN-C enhanced cartilage degeneration in the spontaneous OA in aged joints and surgical OA model. The clinical significance of TN-C effects on cartilage is not straightforward.

Extracellular matrix-mediated cellular communication in the heart

The extracellular matrix (ECM) is a complex and dynamic scaffold that maintains tissue structure and dynamics. However, the view of the ECM as an inert architectural support has been increasingly challenged. The ECM is a vibrant meshwork, a crucial organizer of cellular microenvironments. It plays a direct role in cellular interactions regulating cell growth, survival, spreading, proliferation, differentiation and migration through the intricate relationship among cellular and acellular tissue components. This complex interrelationship preserves cardiac function during homeostasis; however it is also responsible for pathologic remodeling following myocardial injury. Therefore, enhancing our understanding of this cross-talk may provide mechanistic insights into the pathogenesis of heart failure and suggest new approaches to novel, targeted pharmacologic therapies. This review explores the implications of ECM-cell interactions in myocardial cell behavior and cardiac function at baseline and following myocardial injury.

Tenascin-C: Form versus function

Tenascin-C is a large, multimodular, extracellular matrix glycoprotein that exhibits a very restricted pattern of expression but an enormously diverse range of functions. Here, we discuss the importance of deciphering the expression pattern of, and effects mediated by, different forms of this molecule in order to fully understand tenascin-C biology. We focus on both post transcriptional and post translational events such as splicing, glycosylation, assembly into a 3D matrix and proteolytic cleavage, highlighting how these modifications are key to defining tenascin-C function.

Role of tenascins in the ECM of gliomas

Tenascins are a family of extracellular matrix molecules that are mainly expressed in embryonic development and down-regulated in adulthood. A re-expression in the adult occurs under pathological conditions such as inflammation, regeneration or neoplasia. As the most prominent member of the tenascin family, TN-C, is highly expressed in glioma tissue and rising evidence suggests that TN-C plays a crucial role in cell migration or invasion - the most fatal characteristics of glioma - also the other members of this protein family have been investigated with regard to their impact on glioma biology. For all tenascins correlations between the expression levels of the different family members and the degree of malignancy and invasiveness of glial tumors could be detected. Overall, the former and recent results in the research on glioma and tenascins point at distinct roles of each of the molecules in glioma biology and the devastating properties of these tumors.

The tumor-targeting immunocytokine F16-IL2 in combination with doxorubicin: dose escalation in patients with advanced solid tumors and expansion into patients with metastatic breast cancer

A phase Ib/II trial was performed to evaluate safety, tolerability, recommended dose (RD) and efficacy of F16-IL2, a recombinant antibody-cytokine fusion protein, in combination with doxorubicin in patients with solid tumors (phase Ib) and metastatic breast cancer (phase II). Six patient cohorts with progressive solid tumors (n = 19) received escalating doses of F16-IL2 [5-25 Million International Units (MIU) of IL2 equivalent dose] in combination with escalating doses of doxorubicin (0-25 mg/m(2)) on day 1, 8 and 15 every 4 weeks. Subsequently, patients with metastatic breast cancer (n = 10) received the drug combination at the RD. Clinical data and laboratory findings were analyzed for safety, tolerability, and activity. F16-IL2 could be administered up to 25 MIU, in combination with the RD of doxorubicin (25 mg/m(2)). No human anti-fusion protein antibodies (HAFA) response was detected. Pharmacokinetics of F16-IL2 was dose-dependent over the tested range, with half-lives of ca. 13 and ca. 8 hours for cohorts dosed at lower and higher levels, respectively. Toxicities were controllable and reversible, with no combination treatment-related death. After 8 weeks, 57% and 67% disease control rates were observed for Phase I and II, respectively (decreasing to 43% and 33% after 12 weeks), considering 14 and 9 patients evaluable for efficacy. One patient experienced a long lasting partial response (45 weeks), still on-going at exit of study. F16-IL2 can be safely and repeatedly administered at the RD of 25 MIU in combination with 25 mg/m(2) doxorubicin; its safety and activity are currently being investigated in combination with other chemotherapeutics, in order to establish optimal therapy settings.

Host Protein Biomarkers Identify Active Tuberculosis in HIV Uninfected and Co-infected Individuals

Biomarkers for active tuberculosis (TB) are urgently needed to improve rapid TB diagnosis. The objective of this study was to identify serum protein expression changes associated with TB but not latent Mycobacterium tuberculosis infection (LTBI), uninfected states, or respiratory diseases other than TB (ORD). Serum samples from 209 HIV uninfected (HIV⁻) and co-infected (HIV⁺) individuals were studied. In the discovery phase samples were analyzed via liquid chromatography and mass spectrometry, and in the verification phase biologically independent samples were analyzed via a multiplex multiple reaction monitoring mass spectrometry (MRM-MS) assay. Compared to LTBI and ORD, host proteins were significantly differentially expressed in TB, and involved in the immune response, tissue repair, and lipid metabolism. Biomarker panels whose composition differed according to HIV status, and consisted of 8 host proteins in HIV⁻ individuals (CD14, SEPP1, SELL, TNXB, LUM, PEPD, QSOX1, COMP, APOC1), or 10 host proteins in HIV⁺ individuals (CD14, SEPP1, PGLYRP2, PFN1, VASN, CPN2, TAGLN2, IGFBP6), respectively, distinguished TB from ORD with excellent accuracy (AUC = 0.96 for HIV⁻ TB, 0.95 for HIV⁺ TB). These results warrant validation in larger studies but provide promise that host protein biomarkers could be the basis for a rapid, blood-based test for TB.

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Active tuberculosis leads to the differential expression of serum proteins involved in associated host processes.

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Serum protein expression changes in tuberculosis involve the immune response, tissue repair, and lipid metabolism.

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Panels of 8–10 host proteins can distinguish active tuberculosis from latent infection, and other respiratory diseases.

Accurate biomarkers for active tuberculosis (TB) are urgently needed to improve rapid diagnosis. Current diagnostics for TB rely on microbiologic or molecular confirmation of M. tuberculosis, and are therefore dependent on a specimen from the site of disease which is not always accessible. This study demonstrates that human host proteins are differentially expressed in TB compared to latent M. tuberculosis infection, or respiratory diseases other than TB. Our data thus provide promise that host proteins have the potential to become the basis of rapid blood tests that do not require a sample from the site of disease.

Identification of recurrent regulated alternative splicing events across human solid tumors

Cancer is a complex disease that involves aberrant gene expression regulation. Discriminating the modified expression patterns driving tumor biology from the many that have no or little contribution is important for understanding cancer molecular basis. Recurrent deregulation patterns observed in multiple cancer types are enriched for such driver events. Here, we studied splicing alterations in hundreds of matched tumor and normal RNA-seq samples of eight solid cancer types. We found hundreds of cassette exons for which splicing was altered in multiple cancer types and identified a set of highly frequent altered splicing events. Specific splicing regulators, including RBFOX2, MBNL1/2 and QKI, appear to account for many splicing alteration events in multiple cancer types. Together, our results provide a first global analysis of regulated splicing alterations in cancer and identify common events with a potential causative role in solid tumor development.

Immunobiology and immunotherapeutic targeting of glioma stem cells

For decades human brain tumors have confounded our efforts to effectively manage and treat patients. In adults, glioblastoma multiforme is the most common malignant brain tumor with a patient survival of just over 14 months. In children, brain tumors are the leading cause of solid tumor cancer death and gliomas account for one-fifth of all childhood cancers. Despite advances in conventional treatments such as surgical resection, radiotherapy, and systemic chemotherapy, the incidence and mortality rates for gliomas have essentially stayed the same. Furthermore, research efforts into novel therapeutics that initially appeared promising have yet to show a marked benefit. A shocking and somewhat disturbing view is that investigators and clinicians may have been targeting the wrong cells, resulting in the appearance of the removal or eradication of patient gliomas only to have brain cancer recurrence. Here we review research progress in immunotherapy as it pertains to glioma treatment and how it can and is being adapted to target glioma stem cells (GSCs) as a means of dealing with this potential paradigm.

Altered gene expression patterns during the initiation and promotion stages of neonatally diethylstilbestrol-induced hyperplasia/dysplasia/neoplasia in the hamster uterus

Neonatal treatment of hamsters with diethylstilbestrol (DES) induces uterine hyperplasia/dysplasia/neoplasia (endometrial adenocarcinoma) in adult animals. We subsequently determined that the neonatal DES exposure event directly and permanently disrupts the developing hamster uterus (initiation stage) so that it responds abnormally when it is stimulated with estrogen in adulthood (promotion stage). To identify candidate molecular elements involved in progression of the disruption/neoplastic process, we performed: (1) immunoblot analyses and (2) microarray profiling (Affymetrix Gene Chip System) on sets of uterine protein and RNA extracts, respectively, and (3) immunohistochemical analysis on uterine sections; all from both initiation stage and promotion stage groups of animals. Here we report that: (1) progression of the neonatal DES-induced hyperplasia/dysplasia/neoplasia phenomenon in the hamster uterus involves a wide spectrum of specific gene expression alterations and (2) the gene products involved and their manner of altered expression differ dramatically during the initiation vs. promotion stages of the phenomenon.

Revisiting the matricellular concept

The concept of a matricellular protein was first proposed by Paul Bornstein in the mid-1990s to account for the non-lethal phenotypes of mice with inactivated genes encoding thrombospondin-1, tenascin-C, or SPARC. It was also recognized that these extracellular matrix proteins were primarily counter or de-adhesive. This review reappraises the matricellular concept after nearly two decades of continuous investigation. The expanded matricellular family as well as the diverse and often unexpected functions, cellular location, and interacting partners/receptors of matricellular proteins are considered. Development of therapeutic strategies that target matricellular proteins are discussed in the context of pathology and regenerative medicine.

Tenascin-C is an innate broad-spectrum, HIV-1-neutralizing protein in breast milk

Achieving an AIDS-free generation will require elimination of postnatal transmission of HIV-1 while maintaining the nutritional and immunologic benefits of breastfeeding for infants in developing regions. Maternal/infant antiretroviral prophylaxis can reduce postnatal HIV-1 transmission, yet toxicities and the development of drug-resistant viral strains may limit the effectiveness of this strategy. Interestingly, in the absence of antiretroviral prophylaxis, greater than 90% of infants exposed to HIV-1 via breastfeeding remain uninfected, despite daily mucosal exposure to the virus for up to 2 y. Moreover, milk of uninfected women inherently neutralizes HIV-1 and prevents virus transmission in animal models, yet the factor(s) responsible for this anti-HIV activity is not well-defined. In this report, we identify a primary HIV-1-neutralizing protein in breast milk, Tenascin-C (TNC). TNC is an extracellular matrix protein important in fetal development and wound healing, yet its antimicrobial properties have not previously been established. Purified TNC captured and neutralized multiclade chronic and transmitted/founder HIV-1 variants, and depletion of TNC abolished the HIV-1-neutralizing activity of milk. TNC bound the HIV-1 Envelope protein at a site that is induced upon engagement of its primary receptor, CD4, and is blocked by V3 loop- (19B and F39F) and chemokine coreceptor binding site-directed (17B) monoclonal antibodies. Our results demonstrate the ability of an innate mucosal host protein found in milk to neutralize HIV-1 via binding to the chemokine coreceptor site, potentially explaining why the majority of HIV-1-exposed breastfed infants are protected against mucosal HIV-1 transmission.

Tenascin-C downregulates wnt inhibitor dickkopf-1, promoting tumorigenesis in a neuroendocrine tumor model

The extracellular matrix molecule tenascin-C (TNC) is a major component of the cancer-specific matrix, and high TNC expression is linked to poor prognosis in several cancers. To provide a comprehensive understanding of TNC's functions in cancer, we established an immune-competent transgenic mouse model of pancreatic β-cell carcinogenesis with varying levels of TNC expression and compared stochastic neuroendocrine tumor formation in abundance or absence of TNC. We show that TNC promotes tumor cell survival, the angiogenic switch, more and leaky vessels, carcinoma progression, and lung micrometastasis. TNC downregulates Dickkopf-1 (DKK1) promoter activity through the blocking of actin stress fiber formation, activates Wnt signaling, and induces Wnt target genes in tumor and endothelial cells. Our results implicate DKK1 downregulation as an important mechanism underlying TNC-enhanced tumor progression through the provision of a proangiogenic tumor microenvironment.

Glioma stem cells and immunotherapy for the treatment of malignant gliomas

Stem cell research has led to the discovery of glioma stem cells (GSCs), and because these cells are resistant to chemotherapy and radiotherapy, analysis of their properties has been rapidly pursued for targeted treatment of malignant glioma. Recent studies have also revealed complex crosstalk between GSCs and their specialized environment (niche). Therefore, targeting not only GSCs but also their niche may be a principle for novel therapies of malignant glioma. One possible novel strategy for targeting GSCs and their niches is immunotherapy with different antitumor mechanism(s) from those of conventional therapy. Recent clinical studies of immunotherapy using peptide vaccines and antibodies have shown promising results. This review describes the recent findings related to GSCs and their niches, as well as immunotherapies for glioma, followed by discussion of immunotherapies that target GSCs for the treatment of malignant glioma.

The matrikine tenascin-C protects multipotential stromal cells/mesenchymal stem cells from death cytokines such as FasL

Multipotential stromal cells/mesenchymal stem cells (MSCs) are attractive candidates for regenerative therapy due to the ability of these cells to differentiate and positively influence neighboring cells. However, on implantation for wound reconstruction, these cells are lost as they are challenged by nonspecific inflammation signals generated in the wound environment and in response to any implanted foreign body. We have previously shown that sustained and surface-restricted epidermal growth factor receptor (EGFR) signaling by a tethered form of its prototypal ligand EGF enhances survival of MSC in the presence of death cytokines such as FasL, serum deprivation, and low oxygen in vitro. This was proposed to be due to the plasma membrane restriction of EGFR signaling. Interestingly, during wound repair, an extracellular matrix (ECM) component Tenascin-C (TNC) containing EGF-like repeats (EGFL) and fibronectin-like repeats (FNL) is upregulated. A few of the 14 EGFL on each of the 6 arms, especially the 14th, bind as low-affinity/high-avidity ligands to EGFR causing sustained surface-restricted EGFR signaling. We queried whether signaling by this physiologically relevant EGFR matrikine also protects MSCs from FasL-induced death. MSCs grown on TNC and Collagen I (as TNC by itself is antiadhesive) displayed a survival advantage in the presence of FasL. TNC neither sequestered nor neutralized FasL; rather, the effects of survival were via cell signaling. This survival was dependent on TNC activating EGFR and downstream pathways of Erk and Akt through EGFL; to a much lesser extent, the FNL of TNC also contributed to survival. Taken together, these results suggest that providing MSCs with a nonimmunogenic naturally occurring ECM moiety such as TNC enhances their survival in the presence of death factors, and this advantage occurs via signaling through EGFR primarily and integrins only to a minor extent. This matrix component is proposed to supplement MSC delivery on the scaffolds to provide a survival advantage against death upon in vivo implantation.

Matricellular proteins in cardiac adaptation and disease

The term matricellular proteins describes a family of structurally unrelated extracellular macromolecules that, unlike structural matrix proteins, do not play a primary role in tissue architecture, but are induced following injury and modulate cell-cell and cell-matrix interactions. When released to the matrix, matricellular proteins associate with growth factors, cytokines, and other bioactive effectors and bind to cell surface receptors transducing signaling cascades. Matricellular proteins are upregulated in the injured and remodeling heart and play an important role in regulation of inflammatory, reparative, fibrotic and angiogenic pathways. Thrombospondin (TSP)-1, -2, and -4 as well as tenascin-C and -X secreted protein acidic and rich in cysteine (SPARC), osteopontin, periostin, and members of the CCN family (including CCN1 and CCN2/connective tissue growth factor) are involved in a variety of cardiac pathophysiological conditions, including myocardial infarction, cardiac hypertrophy and fibrosis, aging-associated myocardial remodeling, myocarditis, diabetic cardiomyopathy, and valvular disease. This review discusses the properties and characteristics of the matricellular proteins and presents our current knowledge on their role in cardiac adaptation and disease. Understanding the role of matricellular proteins in myocardial pathophysiology and identification of the functional domains responsible for their actions may lead to design of peptides with therapeutic potential for patients with heart disease.

How do tenascins influence the birth and life of a malignant cell?

Tenascins are large glycoproteins found in embryonic and adult extracellular matrices. Of the four family members, two have been shown to be overexpressed in the microenvironment of solid tumours: tenascin-C and tenascin-W. The regular presence of these proteins in tumours suggests a role in tumourigenesis, which has been investigated intensively for tenascin-C and recently for tenascin-W as well. In this review, we follow a malignant cell starting from its birth through its potential metastatic journey and describe how tenascin-C and tenascin-W contribute to these successive steps of tumourigenesis. We consider the importance of the mechanical aspect in tenascin signalling. Furthermore, we discuss studies describing tenascin-C as an important component of stem cell niches and present examples reporting its role in cancer therapy resistance.

Matrikines and the lungs

The extracellular matrix is a complex network of fibrous and nonfibrous molecules that not only provide structure to the lung but also interact with and regulate the behaviour of the cells which it surrounds. Recently it has been recognised that components of the extracellular matrix proteins are released, often through the action of endogenous proteases, and these fragments are termed matrikines. Matrikines have biological activities, independent of their role within the extracellular matrix structure, which may play important roles in the lung in health and disease pathology. Integrins are the primary cell surface receptors, characterised to date, which are used by the matrikines to exert their effects on cells. However, evidence is emerging for the need for co-factors and other receptors for the matrikines to exert their effects on cells. The potential for matrikines, and peptides derived from these extracellular matrix protein fragments, as therapeutic agents has recently been recognised. The natural role of these matrikines (including inhibitors of angiogenesis and possibly inflammation) make them ideal targets to mimic as therapies. A number of these peptides have been taken forward into clinical trials. The focus of this review will be to summarise our current understanding of the role, and potential for highly relevant actions, of matrikines in lung health and disease.

The adhesion modulating properties of tenascin-W

Tenascins are extracellular matrix glycoproteins associated with cell motility, proliferation and differentiation. Tenascin-C inhibits cell spreading by binding to fibronectin; tenascin-R and tenascin-X also have anti-adhesive properties in vitro. Here we have studied the adhesion modulating properties of the most recently characterized tenascin, tenascin-W. C2C12 cells, a murine myoblast cell line, will form broad lamellipodia with stress fibers and focal adhesion complexes after culture on fibronectin. In contrast, C2C12 cells cultured on tenascin-W fail to spread and form stress fibers or focal adhesion complexes, and instead acquire a multipolar shape with short, actin-tipped pseudopodia. The same stellate morphology is observed when C2C12 cells are cultured on a mixture of fibronectin and tenascin-W, or on fibronectin in the presence of soluble tenascin-W. Tenascin-W combined with fibronectin also inhibits the spreading of mouse embryo fibroblasts when compared with cells cultured on fibronectin alone. The similarity between the adhesion modulating effects of tenascin-W and tenascin-C in vitro led us to study the possibility of tenascin-W compensating for tenascin-C in tenascin-C knockout mice, especially during epidermal wound healing. Dermal fibroblasts harvested from a tenascin-C knockout mouse express tenascin-W, but dermal fibroblasts taken from a wild type mouse do not. However, there is no upregulation of tenascin-W in the dermis of tenascin-C knockout mice, or in the granulation tissue of skin wounds in tenascin-C knockout animals. Similarly, tenascin-X is not upregulated in early wound granulation tissue in the tenascin-C knockout mice. Thus, tenascin-W is able to inhibit cell spreading in vitro and it is upregulated in dermal fibroblasts taken from the tenascin-C knockout mouse, but neither it nor tenascin-X are likely to compensate for missing tenascin-C during wound healing.

Toward in vivo imaging of heart disease using a radiolabeled single-chain Fv fragment targeting tenascin-C

Antibodies specific to a particular target molecule can be used as analytical reagents, not only for in vitro immunoassays but also for noninvasive in vivo imaging, e.g., immunoscintigraphies. In the latter case, it is important to reduce the size of antibody molecules in order to achieve suitable in vivo "diagnostic kinetics" and generate higher-resolution images. For these purposes, single-chain Fv fragments (scFvs; M(r) < 30 kDa) have greater potential than intact immunoglobulins (~150 kDa) or Fab (or Fab') fragments (~50 kDa). Our recent observation of enhanced tenascin-C (Tnc) expression at sites of cardiac repair after myocardial infarction prompted us to develop a radiolabeled scFv against Tnc for in vivo imaging of heart disease. We cloned the genes encoding the heavy and light chain variable domains of the mouse anti-Tnc monoclonal antibody 4F10, and combined them to create a single gene. The resulting scFv-4F10 gene was expressed in E. coli cells to produce soluble scFv proteins. scFv-4F10 has an affinity for Tnc (K(a) = 3.5 × 10(7) M(-1)), similar to the Fab fragment of antibody 4F10 (K(a) = 1.3 × 10(7) M(-1)) and high enough to be of practical use. A cysteine residue was then added to the C-terminus to achieve site-specific (111)In labeling via a chelating group. The resulting (111)In-labeled scFv was administered to a rat model of acute myocardial infarction. Biodistribution and quantitative autoradiographic studies indicated higher uptake of the radioactivity at the infarcted myocardium than the noninfarcted one. Single photon emission computed tomography (SPECT) provided in vivo cardiac images that coincided with the ex vivo observations. Our results will promote advances in diagnostic strategies for heart disease.

Influence of Collagen and Chondroitin Sulfate (CS) Coatings on Poly-(Lactide-co-Glycolide) (PLGA) on MG 63 Osteoblast-Like Cells

Poly-(lactide-co-glycolide) (PLGA) is an FDA-approved biodegradable polymer which has been widely used as a scaffold for tissue engineering applications. Collagen has been used as a coating material for bone contact materials, but relatively little interest has focused on biomimetic coating of PLGA with extracellular matrix components such as collagen and the glycosaminoglycan chondroitin sulfate (CS). In this study, PLGA films were coated with collagen type I or collagen I with CS (collagen I/CS) to investigate the effect of CS on the behaviour of the osteoblastic cell line MG 63. Collagen I/CS coatings promoted a significant increase in cell number after 3 days (in comparison to PLGA) and after 7 days (in comparison to PLGA and collagen-coated PLGA). No influence of collagen I or collagen I/CS coatings on the spreading area after 1 day of culture was observed. However, the cells on collagen I/CS formed numerous filopodia and displayed well developed vinculin-containing focal adhesion plaques. Moreover, these cells contained a significantly higher concentration of osteocalcin, measured per mg of protein, than the cells on the pure collagen coating. Thus, it can be concluded that collagen I/CS coatings promote MG 63 cell proliferation, improve cell adhesion and enhance osteogenic cell differentiation.

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.

SPARC mediates Src-induced disruption of actin cytoskeleton via inactivation of small GTPases Rho-Rac-Cdc42

The matricellular glycoprotein Secreted Protein Acidic and Rich in Cysteine (SPARC) plays an important role in the regulation of cell adhesion and proliferation as well as in tumorigenesis and metastasis. Earlier, we reported that, in addition to its potent anti-angiogenic functions, SPARC also induces apoptosis in medulloblastoma cells, mediated by autophagy. We therefore sought to investigate the underlying molecular mechanism through which SPARC inhibits migration and invasion of Daoy medulloblastoma cells, both in vitro and in vivo. For this study, we used SPARC-overexpressing stable Daoy medulloblastoma cells. SPARC overexpression in Daoy medulloblastoma cells inhibited migration and invasion in vitro. Additionally, SPARC overexpression significantly suppressed the activity of Rho, Rac and Cdc42, which all regulate the actin cytoskeleton. This suppression was accompanied by an increase in the phosphorylation of Src at Tyr-416, which led to a loss of actin stress fibers and focal contacts and a decrease in the phosphorylation level of cofilin. The reduced phosphorylation level of cofilin, which is indicative of receding Rho function, in turn led to inhibition of active Rho A. To confirm the role of SPARC in inhibition of migration and invasion of Daoy medulloblastoma cells, we transfected parental and SPARC-overexpressing Daoy cells with a plasmid vector carrying siRNA against SPARC. Transfection with SPARC siRNA reversed Src-mediated disruption of the cytoskeleton organization as well as dephosphorylation of cofilin and activation of Rho A. Taken together, these results establish SPARC as an effector of Src-induced cytoskeleton disruption in Daoy medulloblastoma cells, which subsequently led to decreased migration and invasion.

The role of tenascin C in cardiovascular disease

The extracellular matrix protein tenascin C (TnC) is expressed in a variety of embryonic tissues, but its expression in adult arteries is co-incident with sites of vascular disease. TnC expression has been linked to the development and complications of intimal hyperplasia, pulmonary artery hypertension, atherosclerosis, myocardial infarction, and heart failure. This review identifies the growing collection of evidence linking TnC with cardiovascular disease development. The transient upregulation of this extracellular matrix protein at sites of vascular disease could provide a means to target TnC in the development of diagnostics and new therapies. Studies in TnC-deficient mice have implicated this protein in the development of intimal hyperplasia. Further animal and human studies are required to thoroughly assess the role of TnC in some of the other pathologies it has been linked with, such as atherosclerosis and pulmonary hypertension. Large population studies are also warranted to clarify the diagnostic value of this extracellular matrix protein in cardiovascular disease, for example by targeting its expression using radiolabelled antibodies or measuring circulating concentrations of TnC.

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.

Transcriptome analysis of the desert locust central nervous system: production and annotation of a Schistocerca gregaria EST database

BACKGROUND

The desert locust (Schistocerca gregaria) displays a fascinating type of phenotypic plasticity, designated as 'phase polyphenism'. Depending on environmental conditions, one genome can be translated into two highly divergent phenotypes, termed the solitarious and gregarious (swarming) phase. Although many of the underlying molecular events remain elusive, the central nervous system (CNS) is expected to play a crucial role in the phase transition process. Locusts have also proven to be interesting model organisms in a physiological and neurobiological research context. However, molecular studies in locusts are hampered by the fact that genome/transcriptome sequence information available for this branch of insects is still limited.

METHODOLOGY

We have generated 34,672 raw expressed sequence tags (EST) from the CNS of desert locusts in both phases. These ESTs were assembled in 12,709 unique transcript sequences and nearly 4,000 sequences were functionally annotated. Moreover, the obtained S. gregaria EST information is highly complementary to the existing orthopteran transcriptomic data. Since many novel transcripts encode neuronal signaling and signal transduction components, this paper includes an overview of these sequences. Furthermore, several transcripts being differentially represented in solitarious and gregarious locusts were retrieved from this EST database. The findings highlight the involvement of the CNS in the phase transition process and indicate that this novel annotated database may also add to the emerging knowledge of concomitant neuronal signaling and neuroplasticity events.

CONCLUSIONS

In summary, we met the need for novel sequence data from desert locust CNS. To our knowledge, we hereby also present the first insect EST database that is derived from the complete CNS. The obtained S. gregaria EST data constitute an important new source of information that will be instrumental in further unraveling the molecular principles of phase polyphenism, in further establishing locusts as valuable research model organisms and in molecular evolutionary and comparative entomology.

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.

The calreticulin-binding sequence of thrombospondin 1 regulates collagen expression and organization during tissue remodeling

Amino acids 17-35 of the thrombospondin1 (TSP1) N-terminal domain (NTD) bind cell surface calreticulin to signal focal adhesion disassembly, cell migration, and anoikis resistance in vitro. However, the in vivo relevance of this signaling pathway has not been previously determined. We engineered local in vivo expression of the TSP1 calreticulin-binding sequence to determine the role of TSP1 in tissue remodeling. Surgical sponges impregnated with a plasmid encoding the secreted calreticulin-binding sequence [NTD (1-35)-EGFP] or a control sequence [mod NTD (1-35)-EGFP] tagged with enhanced green fluorescent protein were implanted subcutaneously in mice. Sponges expressing NTD (1-35)-EFGP formed a highly organized capsule despite no differences in cellular composition, suggesting stimulation of collagen deposition by the calreticulin-binding sequence of TSP1. TSP1, recombinant NTD, or a peptide of the TSP1 calreticulin-binding sequence (hep I) increased both collagen expression and matrix deposition by fibroblasts in vitro. TSP1 stimulation of collagen was inhibited by a peptide that blocks TSP1 binding to calreticulin, demonstrating the requirement for cell surface calreticulin. Collagen stimulation was independent of TGF-β activity and Smad phosphorylation but was blocked by an Akt inhibitor, suggesting that signaling through the Akt pathway is important for regulation of collagen through TSP1 binding to calreticulin. These studies identify a novel function for the NTD of TSP1 as a mediator of collagen expression and deposition during tissue remodeling.

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.

The effect of high-energy extracorporeal shock waves on hyaline cartilage of adult rats in vivo

The aim of this study was to determine if extracorporeal shock wave therapy (ESWT) in vivo affects the structural integrity of articular cartilage. A single bout of ESWT (1500 shock waves of 0.5 mJ/mm(2)) was applied to femoral heads of 18 adult Sprague-Dawley rats. Two sham-treated animals served as controls. Cartilage of each femoral head was harvested at 1, 4, or 10 weeks after ESWT (n = 6 per treatment group) and scored on safranin-O-stained sections. Expression of tenascin-C and chitinase 3-like protein 1 (Chi3L1) was analyzed by immunohistochemistry. Quantitative real-time polymerase chain reaction (PCR) was used to examine collagen (II)alpha(1) (COL2A1) expression and chondrocyte morphology was investigated by transmission electron microscopy no changes in Mankin scores were observed after ESWT. Positive immunostaining for tenascin-C and Chi3L1 was found up to 10 weeks after ESWT in experimental but not in control cartilage. COL2A1 mRNA was increased in samples 1 and 4 weeks after ESWT. Alterations found on the ultrastructural level showed expansion of the rough-surfaced endoplasmatic reticulum, detachment of the cell membrane and necrotic chondrocytes. Extracorporeal shock waves caused alterations of hyaline cartilage on a molecular and ultrastructural level that were distinctly different from control. Similar changes were described before in the very early phase of osteoarthritis (OA). High-energy ESWT might therefore cause degenerative changes in hyaline cartilage as they are found in initial OA.

Role of matricellular proteins in cardiac tissue remodeling after myocardial infarction

After onset of myocardial infarction (MI), the left ventricle (LV) undergoes a continuum of molecular, cellular, and extracellular responses that result in LV wall thinning, dilatation, and dysfunction. These dynamic changes in LV shape, size, and function are termed cardiac remodeling. If the cardiac healing after MI does not proceed properly, it could lead to cardiac rupture or maladaptive cardiac remodeling, such as further LV dilatation and dysfunction, and ultimately death. Although the precise molecular mechanisms in this cardiac healing process have not been fully elucidated, this process is strictly coordinated by the interaction of cells with their surrounding extracellular matrix (ECM) proteins. The components of ECM include basic structural proteins such as collagen, elastin and specialized proteins such as fibronectin, proteoglycans and matricellular proteins. Matricellular proteins are a class of non-structural and secreted proteins that probably exert regulatory functions through direct binding to cell surface receptors, other matrix proteins, and soluble extracellular factors such as growth factors and cytokines. This small group of proteins, which includes osteopontin, thrombospondin-1/2, tenascin, periostin, and secreted protein, acidic and rich in cysteine, shows a low level of expression in normal adult tissue, but is markedly upregulated during wound healing and tissue remodeling, including MI. In this review, we focus on the regulatory functions of matricellular proteins during cardiac tissue healing and remodeling after MI.

Quantitative analysis of three-dimensional human mammary epithelial tissue architecture reveals a role for tenascin-C in regulating c-met function

Remodeling of the stromal extracellular matrix and elevated expression of specific proto-oncogenes within the adjacent epithelium represent cardinal features of breast cancer, yet how these events become integrated is not fully understood. To address this question, we focused on tenascin-C (TN-C), a stromal extracellular matrix glycoprotein whose expression increases with disease severity. Initially, nonmalignant human mammary epithelial cells (MCF-10A) were cultured within a reconstituted basement membrane (BM) where they formed three-dimensional (3-D) polarized, growth-attenuated, multicellular acini, enveloped by a continuous endogenous BM. In the presence of TN-C, however, acini failed to generate a normal BM, and net epithelial cell proliferation increased. To quantify how TN-C alters 3-D tissue architecture and function, we developed a computational image analysis algorithm, which showed that although TN-C disrupted acinar surface structure, it had no effect on their volume. Thus, TN-C promoted epithelial cell proliferation leading to luminal filling, a process that we hypothesized involved c-met, a proto-oncogene amplified in breast tumors that promotes intraluminal filling. Indeed, TN-C increased epithelial c-met expression and promoted luminal filling, whereas blockade of c-met function reversed this phenotype, resulting in normal BM deposition, proper lumen formation, and decreased cell proliferation. Collectively, these studies, combining a novel quantitative image analysis tool with 3-D organotypic cultures, demonstrate that stromal changes associated with breast cancer can control proto-oncogene function.

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.

Tumour-associated tenascin-C isoforms promote breast cancer cell invasion and growth by matrix metalloproteinase-dependent and independent mechanisms

INTRODUCTION

The stromal microenvironment has a profound influence on tumour cell behaviour. In tumours, the extracellular matrix (ECM) composition differs from normal tissue and allows novel interactions to influence tumour cell function. The ECM protein tenascin-C (TNC) is frequently up-regulated in breast cancer and we have previously identified two novel isoforms - one containing exon 16 (TNC-16) and one containing exons 14 plus 16 (TNC-14/16).

METHODS

The present study has analysed the functional significance of this altered TNC isoform profile in breast cancer. TNC-16 and TNC-14/16 splice variants were generated using PCR-ligation and over-expressed in breast cancer cells (MCF-7, T47D, MDA-MD-231, MDA-MB-468, GI101) and human fibroblasts. The effects of these variants on tumour cell invasion and proliferation were measured and compared with the effects of the large (TNC-L) and fully spliced small (TNC-S) isoforms.

RESULTS

TNC-16 and TNC-14/16 significantly enhanced tumour cell proliferation (P < 0.05) and invasion, both directly (P < 0.01) and as a response to transfected fibroblast expression (P < 0.05) with this effect being dependent on tumour cell interaction with TNC, because TNC-blocking antibodies abrogated these responses. An analysis of 19 matrix metalloproteinases (MMPs) and tissue inhibitor of matrix metalloproteinases 1 to 4 (TIMP 1 to 4) revealed that TNC up-regulated expression of MMP-13 and TIMP-3 two to four fold relative to vector, and invasion was reduced in the presence of MMP inhibitor GM6001. However, this effect was not isoform-specific but was elicited equally by all TNC isoforms.

CONCLUSIONS

These results demonstrate a dual requirement for TNC and MMP in enhancing breast cancer cell invasion, and identify a significant role for the tumour-associated TNC-16 and TNC-14/16 in promoting tumour invasion, although these isoform-specific effects appear to be mediated through MMP-independent mechanisms.