Opposite regulation of tenascin-C and tenascin-X in MeLiM swine heritable cutaneous malignant melanoma

A virological view of tenascin-C in infection

Tenascin-C is a large extracellular matrix glycoprotein with complex, not yet fully unveiled roles. Its context- and structure-dependent modus operandi renders tenascin-C a puzzling protein. Since its discovery ∼40 years ago, research into tenascin-C biology continues to reveal novel functions, the most recent of all being its immunomodulatory activity, especially its role in infection, which is just now beginning to emerge. Here, we explore the role of tenascin-C in the immune response to viruses, including SARS-CoV-2 and HIV-1. Recently, tenascin-C has emerged as a biomarker of disease severity during COVID-19 and other viral infections, and we highlight relevant RNA sequencing and proteomic analyses that suggest a correlation between tenascin-C levels and disease severity. Finally, we ask what the function of this protein during viral replication is and propose tenascin-C as an intercellular signal of inflammation shuttled to distal sites via exosomes, a player in the repair and remodeling of infected and damaged tissues during severe infectious disease, as well as a ligand for specific pathogens with distinct implications for the host.

Revisiting the Tenascins: Exploitable as Cancer Targets?

For their full manifestation, tumors require support from the surrounding tumor microenvironment (TME), which includes a specific extracellular matrix (ECM), vasculature, and a variety of non-malignant host cells. Together, these components form a tumor-permissive niche that significantly differs from physiological conditions. While the TME helps to promote tumor progression, its special composition also provides potential targets for anti-cancer therapy. Targeting tumor-specific ECM molecules and stromal cells or disrupting aberrant mesenchyme-cancer communications might normalize the TME and improve cancer treatment outcome. The tenascins are a family of large, multifunctional extracellular glycoproteins consisting of four members. Although each have been described to be expressed in the ECM surrounding cancer cells, tenascin-C and tenascin-W are currently the most promising candidates for exploitability and clinical use as they are highly expressed in various tumor stroma with relatively low abundance in healthy tissues. Here, we review what is known about expression of all four tenascin family members in tumors, followed by a more thorough discussion on tenascin-C and tenascin-W focusing on their oncogenic functions and their potential as diagnostic and/or targetable molecules for anti-cancer treatment purposes.

miRNA-149 targets PARP-2 in endometrial epithelial and stromal cells to regulate the trophoblast attachment process

Embryo implantation is a highly complex process involving many regulatory factors, including several micro RNAs (miRNAs/miRs). One miRNA present in the stromal cells of normal endometrium is miR-149, which targets poly (ADP-ribose) polymerase 2 (PARP-2), a gene involved in endometrial receptivity for trophoblast implantation. However, the precise role of miR-149 in the endometrial receptivity during blastocyst implantation is still unknown. We studied miR-149-dependent PARP-2 regulation during trophoblast attachment to endometrial epithelial cells. Using FISH, we found that miR-149 is expressed in mouse endometrial epithelial and stromal cells at implantation and inter-implantation sites. Endometrial receptivity for embryo implantation and attachment is inhibited by the upregulation of miR-149 in the endometrium. Our RT-PCR analysis revealed downregulation of miR-149 in the implantation region of the uterus during the receptive stage (Day 5, 0500 h, p.c.) in the mouse. Under in-vitro conditions, miR-149 overexpression in human endometrial epithelial cells (hEECs) abrogated the human trophoblastic cells spheroid and mouse blastocyst attachment. Subsequently, miR-149 also regulates transformed human endometrial stromal cell (T-hESCs) decidualization by downregulating PARP-2 and upregulating caspase-8 proteins. Overexpression of miR-149 in hEECs and downregulated PARP-2 protein expression, reconfirming that PARP-2 is a downstream target of miR-149 in endometrial cells as well. miR-149 is also able to alter the expression of caspase-8, another PARP-2 regulator. In conclusion, our data indicate that miR-149 is one of the regulators of endometrial receptivity and decidualization for trophoblast implantation, and it exerts the effects by acting on the downstream targets PARP-2 and caspase-8.

The Roles of Tenascins in Cardiovascular, Inflammatory, and Heritable Connective Tissue Diseases

Tenascins are a family of multifunctional extracellular matrix (ECM) glycoproteins with time- and tissue specific expression patterns during development, tissue homeostasis, and diseases. There are four family members (tenascin-C, -R, -X, -W) in vertebrates. Among them, tenascin-X (TNX) and tenascin-C (TNC) play important roles in human pathologies. TNX is expressed widely in loose connective tissues. TNX contributes to the stability and maintenance of the collagen network, and its absence causes classical-like Ehlers-Danlos syndrome (clEDS), a heritable connective tissue disorder. In contrast, TNC is specifically and transiently expressed upon pathological conditions such as inflammation, fibrosis, and cancer. There is growing evidence that TNC is involved in inflammatory processes with proinflammatory or anti-inflammatory activity in a context-dependent manner. In this review, we summarize the roles of these two tenascins, TNX and TNC, in cardiovascular and inflammatory diseases and in clEDS, and we discuss the functional consequences of the expression of these tenascins for tissue homeostasis.

Loss of Tenascin-X expression during tumor progression: A new pan-cancer marker

Cancer is a systemic disease involving multiple components produced from both tumor cells themselves and surrounding stromal cells. The pro- or anti-tumoral role of the stroma is still under debate. Indeed, it has long been considered the main physical barrier to the diffusion of chemotherapy by its dense and fibrous nature and its poor vascularization. However, in murine models, the depletion of fibroblasts, the main ExtraCellular Matrix (ECM)-producing cells, led to more aggressive tumors even though they were more susceptible to anti-angiogenic and immuno-modulators. Tenascin-C (TNC) is a multifunctional matricellular glycoprotein (i.e. an ECM protein also able to induce signaling pathway) and is considered as a marker of tumor expansion and metastasis. However, the status of other tenascin (TN) family members and particularly Tenascin-X (TNX) has been far less studied during this pathological process and is still controversial. Herein, through (1) in silico analyses of the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) databases and (2) immunohistochemistry staining of Tissue MicroArrays (TMA), we performed a large and extensive study of TNX expression at both mRNA and protein levels (1) in the 6 cancers with the highest incidence and mortality in the world (i.e. lung, breast, colorectal, prostate, stomach and liver) and (2) in the cancers for which sparse data regarding TNX expression already exist in the literature. We thus demonstrated that, in most cancers, TNX expression is significantly downregulated during cancer progression and we also highlighted, when data were available, that high TNXB mRNA expression in cancer is correlated with a good survival prognosis.

Melanoma-Bearing Libechov Minipig (MeLiM): The Unique Swine Model of Hereditary Metastatic Melanoma

National cancer databases document that melanoma is the most aggressive and deadly cutaneous malignancy with worldwide increasing incidence in the Caucasian population. Around 10% of melanomas occur in families. Several germline mutations were identified that might help to indicate individuals at risk for preventive interventions and early disease detection. More than 50% of sporadic melanomas carry mutations in Ras/Raf/mitogen-activated protein kinase (MAPK/MEK) pathway, which may represent aims of novel targeted therapies. Despite advances in targeted therapies and immunotherapies, the outcomes in metastatic tumor are still unsatisfactory. Here, we review animal models that help our understanding of melanoma development and treatment, including non-vertebrate, mouse, swine, and other mammal models, with an emphasis on those with spontaneously developing melanoma. Special attention is paid to the melanoma-bearing Libechov minipig (MeLiM). This original swine model of hereditary metastatic melanoma enables studying biological processes underlying melanoma progression, as well as spontaneous regression. Current histological, immunohistochemical, biochemical, genetic, hematological, immunological, and skin microbiome findings in the MeLiM model are summarized, together with development of new therapeutic approaches based on tumor devitalization. The ongoing study of molecular and immunological base of spontaneous regression in MeLiM model has potential to bring new knowledge of clinical importance.

Multiple Roles of Tenascins in Homeostasis and Pathophysiology of Aorta

Tenascins are a family of large extracellular matrix (ECM) glycoproteins. Four family members (tenascin-C, -R, -X, and -W) have been identified to date. Each member consists of the same types of structural domains and exhibits time- and tissue-specific expression patterns, suggesting their specific roles in embryonic development and tissue remodeling. Among them, the significant involvement of tenascin-C (TNC) and tenascin-X (TNX) in the progression of vascular diseases has been examined in detail. TNC is strongly up-regulated under pathological conditions, induced by a number of inflammatory mediators and mechanical stress. TNC has diverse functions, particularly in the regulation of inflammatory responses. Recent studies suggest that TNC is involved in the pathophysiology of aneurysmal and dissecting lesions, in part by protecting the vascular wall from destructive mechanical stress. TNX is strongly expressed in vascular walls, and its distribution is often reciprocal to that of TNC. TNX is involved in the stability and maintenance of the collagen network and elastin fibers. A deficiency in TNX results in a form of Ehlers–Danlos syndrome (EDS). Although their exact roles in vascular diseases have not yet been elucidated, TNC and TNX are now being recognized as promising biomarkers for diagnosis and risk stratification of vascular diseases.

MALDI MSI of MeLiM melanoma: Searching for differences in protein profiles

Background

Treatment of advanced cutaneous melanoma remains challenging, and new data on melanoma biology are required. The most widely accepted criteria for the prognostic evaluation of melanoma are histopathological and clinical parameters, and the identification of additional tumor markers is thus of paramount importance. Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI), an important tool in cancer research, is useful for unraveling the molecular profile of melanoma.

Methodology/Principal findings

In this report, we used the melanoma-bearing Libechov minipig (MeLiM), a unique animal model that allows observation of the complete spontaneous regression of invasive cutaneous melanoma, to investigate i) the differences between melanoma and healthy skin protein profiles and ii) the proteins potentially involved in spontaneous regression. The MeLiM tissues were cryosected, histologically characterized, analyzed by MALDI MSI, and immunohistologically stained. Multivariate statistical analyses of the MALDI MSI data revealed ten relevant m/z ions, of which the expression levels varied significantly among the studied MeLiM tissues. These ion peaks were used to create mass ion images/maps and visualize the differences between tumor and healthy skin specimens, as well as among histologically characterized tissue regions.

Conclusions/Significance

Protein profiles comprising ten statistically significant mass ion peaks useful for differentiating cutaneous melanoma and healthy skin tissues were determined. Peaks at m/z 3044, 6011, 6140 and 10180 were overexpressed in melanoma compared with healthy skin tissue. More specifically, m/z 6140 was expressed at significantly (p < 0.05) higher levels in normally growing melanoma regions than in regions with early and late spontaneous regression. This study demonstrates the clinical utility of MALDI MSI for the analysis of tissue cryosections at a molecular level.

The MeLiM Minipig: An Original Spontaneous Model to Explore Cutaneous Melanoma Genetic Basis

Melanoma is the deadliest skin cancer and is a major public health concern with a growing incidence worldwide. As for other complex diseases, animal models are needed in order to better understand the mechanisms leading to pathology, identify potential biomarkers to be used in the clinics, and eventually molecular targets for therapeutic solutions. Cutaneous melanoma, arising from skin melanocytes, is mainly caused by environmental factors such as UV radiation; however a significant genetic component participates in the etiology of the disease. The pig is a recognized model for spontaneous development of melanoma with features similar to the human ones, followed by a complete regression and a vitiligo-like depigmentation. Three different pig models (MeLiM, Sinclair, and MMS-Troll) have been maintained through the last decades, and different genetic studies have evidenced a complex inheritance of the disease. As in humans, pigmentation seems to play a prominent role, notably through MC1R and MITF signaling. Conversely, cell cycle genes as CDKN2A and CDK4 have been excluded as predisposing for melanoma in MeLiM. So far, only sparse studies have focused on somatic changes occurring during oncogenesis, and have revealed major cytological changes and a potential dysfunction of the telomere maintenance system. Finally, the spontaneous tumor progression and regression occurring in these models could shed light on the interplay between endogenous retroviruses, melanomagenesis, and adaptive immune response.

Suppression of hepatic dysfunction in tenascin‑X‑deficient mice fed a high‑fat diet

Extracellular matrix glycoprotein tenascin‑X (TNX) is the largest member of the tenascin family. In the present study, the contribution of TNX to liver dysfunction was investigated by administration of high‑fat and high‑cholesterol diet with high levels of phosphorus and calcium (HFCD) to wild‑type (WT) and TNX‑knockout (KO) mice. After 16 weeks of HFCD administration, the ratio of liver weight to body weight was approximately 22% higher in the HFCD‑fed WT mice compared with the HFCD‑fed TNX‑KO mice, indicating hepatomegaly in HFCD‑fed WT mice. Histological analyses with hematoxylin and eosin staining at 21 weeks revealed that hepatocyte hypertrophy in HFCD‑fed TNX‑KO mice was suppressed to 85% of that in HFCD‑fed WT mice. By contrast, there was a 1.2‑fold increase in lipid deposition in hepatocytes from HFCD‑fed TNX‑KO mice compared with HFCD‑fed WT mice at 18 weeks, as demonstrated by Oil Red O staining. In addition, TNX‑KO mice at 21 weeks and 27 weeks post‑HFCD administration exhibited significant suppression of inflammatory cell infiltrate to 51 and 24% of that in WT mice, respectively. Immunofluorescence analysis for type I collagen and Elastica van Gieson staining demonstrated a clear hepatic fibrosis progression in HFCD‑fed WT mice at 27 weeks, whereas hepatic fibrosis was undetected in HFCD‑fed TNX‑KO mice. The present findings indicated that TNX deficiency suppressed hepatic dysfunction induced by HFCD administration.

Spatial mapping of metals in tissue-sections using combination of mass-spectrometry and histology through image registration

We describe a new procedure for the parallel mapping of selected metals in histologically characterized tissue samples. Mapping is achieved via image registration of digital data obtained from two neighbouring cryosections by scanning the first as a histological sample and subjecting the second to laser ablation inductively coupled plasma mass spectrometry. This computer supported procedure enables determination of the distribution and content of metals of interest directly in the chosen histological zones and represents a substantial improvement over the standard approach, which determines these values in tissue homogenates or whole tissue sections. The potential of the described procedure was demonstrated in a pilot study that analysed Zn and Cu levels in successive development stages of pig melanoma tissue using MeLiM (Melanoma-bearing-Libechov-Minipig) model. We anticipate that the procedure could be useful for a complex understanding of the role that the spatial distribution of metals plays within tissues affected by pathological states including cancer.

Transcriptional regulation of tenascin genes

Extracellular matrix proteins of the tenascin family resemble each other in their domain structure, and also share functions in modulating cell adhesion and cellular responses to growth factors. Despite these common features, the 4 vertebrate tenascins exhibit vastly different expression patterns. Tenascin-R is specific to the central nervous system. Tenascin-C is an “oncofetal” protein controlled by many stimuli (growth factors, cytokines, mechanical stress), but with restricted occurrence in space and time. In contrast, tenascin-X is a constituitive component of connective tissues, and its level is barely affected by external factors. Finally, the expression of tenascin-W is similar to that of tenascin-C but even more limited. In accordance with their highly regulated expression, the promoters of the tenascin-C and -W genes contain TATA boxes, whereas those of the other 2 tenascins do not. This article summarizes what is currently known about the complex transcriptional regulation of the 4 tenascin genes in development and disease.

Tenascin-X: beyond the architectural function

Tenascin-X is the largest member of the tenascin (TN) family of evolutionary conserved extracellular matrix glycoproteins, which also comprises TN-C, TN-R and TN-W. Among this family, TN-X is the only member described so far to exert a crucial architectural function as evidenced by a connective tissue disorder (a recessive form of Ehlers-Danlos syndrome) resulting from a loss-of-function of this glycoprotein in humans and mice. However, TN-X is more than an architectural protein, as it displays features of a matricellular protein by modulating cell adhesion. However, the cellular functions associated with the anti-adhesive properties of TN-X have not yet been revealed. Recent findings indicate that TN-X is also an extracellular regulator of signaling pathways. Indeed, TN-X has been shown to regulate the bioavailability of the Transforming Growth Factor (TGF)-β and to modulate epithelial cell plasticity. The next challenges will be to unravel whether the signaling functions of TN-X are functionally linked to its matricellular properties.

Immunohistochemical Analysis of Collagen IV and Laminin Expression in Spontaneous Melanoma Regression in the Melanoma-Bearing Libechov Minipig

Spontaneous regression (SR) of human melanoma is a rare, well-documented phenomenon that is not still fully understood. Its detailed study cannot be performed in patients due to ethical reasons. Using the Melanoma-bearing Libechov Minipig (MeLiM) animals of various ages (from 3 weeks to 8 months) we implemented a long-term monitoring of melanoma growth and SR. We focused on immunohistochemical detection of two important extracellular matrix proteins, collagen IV and laminin, which are associated with cancer. We showed that SR of melanoma is a highly dynamic process. The expression of collagen IV and laminin correlated with changes in population of melanoma cells. Tumours of 3-week-old animals consisted primarily of melanoma cells with a granular expression of collagen IV and laminin around them. Thereafter, melanoma cells were gradually destroyed and tumour tissue was rebuilt into the connective tissue. Collagen IV expression slightly increased in tumours of 10-week-old pigs showing extracellular fibrous appearance. In tumours of older animals, areas lacking melanoma cells demonstrated a low expression and areas still containing melanoma cells a high expression of both proteins. We considered the age of 10 weeks as a turning point in the transition between tumour growth and SR of the MeLiM melanoma.

Rat mammary extracellular matrix composition and response to ibuprofen treatment during postpartum involution by differential GeLC-MS/MS analysis

Breast cancer patients diagnosed within five years following pregnancy have increased metastasis and decreased survival. A hallmark of postpartum biology that may contribute to this poor prognosis is mammary gland involution, involving massive epithelial cell death and dramatic stromal remodeling. Previous studies show pro-tumorigenic properties of extracellular matrix (ECM) isolated from rodent mammary glands undergoing postpartum involution. More recent work demonstrates systemic ibuprofen treatment during involution decreases its tumor-promotional nature. Utilizing a proteomics approach, we identified relative differences in the composition of mammary ECM isolated from nulliparous rats and those undergoing postpartum involution, with and without ibuprofen treatment. GeLC-MS/MS experiments resulted in 20327 peptide identifications that mapped to 884 proteins with a <0.02% false discovery rate. Label-free quantification yielded several ECM differences between nulliparous and involuting glands related to collagen-fiber organization, cell motility and attachment, and cytokine regulation. Increases in known pro-tumorigenic ECM proteins osteopontin, tenascin-C, and laminin-α1 and pro-inflammatory proteins STAT3 and CD68 further identify candidate mediators of breast cancer progression specific to the involution window. With postpartum ibuprofen treatment, decreases in tenascin-C and three laminin chains were revealed. Our data suggest novel ECM mediators of breast cancer progression and demonstrate a protective influence of ibuprofen on mammary ECM composition.

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.

Utilizing of Adsorptive Transfer Stripping Technique Brdicka Reaction for Determination of Metallothioneins Level in Melanoma Cells, Blood Serum and Tissues

In the paper we utilized the adsorptive transfer stripping differential pulse voltammetry Brdicka reaction for the determination of metallothioneins (MT) in melanoma cells, animal melanoma tissues (MeLiM miniature pig) and blood serum of patients with malignant melanoma. Primarily we attempted to investigate the influence of dilution of real sample on MT electrochemical response. Dilution of samples of 1 000 times was chosen the most suitable for determination of MT level in biological samples. Then we quantified the MT level in the melanoma cells, the animal melanoma tissues and the blood serum samples. The MT content in the cells varied within the range from 4.2 to 11.2 μM. At animal melanoma tissues (melanomas localized on abdomen, back limb and dorsum) the highest content of MT was determined in the tumour sampled on the back of the animal and was nearly 500 μg of MTs per gram of a tissue. We also quantified content of MT in metastases, which was found in liver, spleen and lymph nodes. Moreover the average MT level in the blood serum samples from patients with melanoma was 3.0 ± 0.8 μM. MT levels determined at melanoma samples were significantly (p < 0.05) higher compared to control ones at cells, tissues and blood serum.

Microarray-Based Identification of Tenascin C and Tenascin XB, Genes Possibly Involved in Tumorigenesis Associated with Neurofibromatosis Type 1

PURPOSE

Neurofibromatosis type 1 (NF1) is an autosomal dominant disorder with a complex variety of clinical manifestations. The hallmark of NF1 is the onset of heterogeneous (dermal or plexiform) benign neurofibromas. Plexiform neurofibromas can give rise to malignant peripheral nerve sheath tumors, which are resistant to conventional therapies.

EXPERIMENTAL DESIGN

To identify new signaling pathways involved in the malignant transformation of plexiform neurofibromas, we applied a 22,000-oligonucleotide microarray approach to a series of plexiform neurofibromas and malignant peripheral nerve sheath tumors. Changes in the expression of selected genes were then confirmed by real-time quantitative reverse transcription-PCR.

RESULTS

We identified two tenascin gene family members that were significantly deregulated in both human NF1-associated tumors and NF1-deficient primary cells: Tenascin C (TNC) was up-regulated whereas tenascin XB (TNXB) was down-regulated during tumor progression. TNC activation is mainly due to the up-regulation of large TNC splice variants. Immunohistochemical studies showed that TNC transcripts are translated into TNC protein in TNC-overexpressing tumors. Aberrant transcriptional activation of TNC seems to be principally mediated by activator protein transcription factor complexes.

CONCLUSION

TNXB and TNC may be involved in the malignant transformation of plexiform neurofibromas. Anti-TNC antibodies, already used successfully in clinical trials to treat malignant human gliomas, may be an appropriate new therapeutic strategy for NF1.

Immunohistochemical Expression of Tenascin in Melanocytic Tumours of Dogs

The aim of this study was to investigate tenascin-C (TN) immunolabelling and labelling for endothelium by von Willebrand Factor (vWF) in melanocytic tumours of dogs as compared with normal tissues, to evaluate the TN distribution in these types of tumours and to investigate whether a relation could be established between TN and angiogenesis in different types of tumour. Samples of normal dog skin (n=8), benign skin melanocytomas (n=10), malignant oral melanomas (n=9) and malignant toe melanomas (n=5) were studied. The percentages of TN and vWF immunolabelling per total microscopical area were analysed by morphometric methods. In normal skin, TN was found at dermo-epidermal junctions, around hair follicles, in the smooth muscles of hair follicles, and in the walls of blood vessels. TN immunolabelling (distribution and intensity) in melanocytomas was comparable with that found in normal skin. In melanomas, TN expression was considerably increased, its intensity in toe melanomas being twice that observed in oral melanomas. The degree of TN immunolabelling was not related to the histological malignancy of the melanomas. In melanomas, TN was found in the connective tissue surrounding the tumour cell nests and in narrow stromal strands inside the tumour. Regions infiltrated with lymphocytes were devoid of TN. The presence of TN around capillaries in melanocytomas and melanomas was investigated by double-immunolabelling (for TN and vWF). The intensity of vWF and TN immunolabelling was higher in melanomas than in melanocytomas, and higher in toe melanomas than in oral melanomas; however, no clear relation between TN expression and immunolabelling for vWF was found.

Dermal connective tissue development in mice: an essential role for tenascin-X

Deficiency of the extracellular matrix protein tenascin-X (TNX) causes a recessive form of Ehlers-Danlos syndrome (EDS) characterized by hyperextensible skin and hypermobile joints. It is not known whether the observed alterations of dermal collagen fibrils and elastic fibers in these patients are caused by disturbed assembly and deposition or by altered stability and turnover. We used biophysical measurements and immunofluorescence to study connective tissue properties in TNX knockout and wild-type mice. We found that TNX knockout mice, even at a young age, have greatly disturbed biomechanical properties of the skin. No joint abnormalities were noted at any age. The spatio-temporal expression of TNX during normal mouse skin development, during embryonic days 13-19 (E13-E19), was distinct from tropoelastin and the dermal fibrillar collagens type I, III, and V. Our data show that TNX is not involved in the earliest phase (E10-E14) of the deposition of collagen fibrils and elastic fibers during fetal development. From E15 to E19, TNX starts partially to colocalize with the dermal collagens and elastin, and in adult mice, TNX is present in the entire dermis. In adult TNX knockout mice, we observed an apparent increase of elastin. We conclude that TNX knockout mice only partially recapitulate the phenotype of TNX-deficient EDS patients, and that TNX could potentially be involved in maturation and/or maintenance of the dermal collagen and elastin network.

Tenascin-X deficiency in autosomal recessive Ehlers-Danlos syndrome

We present two unrelated individuals with complete deficiency of tenascin-X, resulting in an autosomal recessive form of Ehlers-Danlos syndrome (EDS). Consistent with the original description of tenascin-X deficiency, these individuals had marked skin hyperextensibility, easy bruising, and joint laxity. Unlike classical EDS they did not have atrophic scarring or poor wound healing. Significant medical problems occurring in these individuals included severe diverticular intestinal disease, mitral valve prolapse requiring valve replacement, and obstructive airway disease.

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

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

The Mechanism of In-Stent Restenosis in Radius Stent-An Experimental Porcine Study-

BACKGROUND

We investigated the mechanism of in-stent restenosis in radius stents in comparison to balloon-expandable stent (NIR stent) in pigs, with a focus on extracellular matrix (ECM).

METHODS AND RESULTS

Radius (n = 4) or NIR (n = 4) stents were implanted in the left coronary arteries of miniature pigs. Quantitative coronary ultrasound (QCU) was performed before, immediately after, and at 1 and 4 weeks after the implantation. The stented-coronary arteries were harvested at 4 weeks after the implantation followed by immunohistochemical, histological, reverse transcription-polymerase chain reaction (RT-PCR) and real-time PCR studies. In QCU, mean luminal areas at 4 weeks did not differ between both groups, whereas the mean stent area and neointimal area were significantly greater in the radius (p < 0.01). The immunohistochemical study revealed a significantly decreased number of neointimal macrophages and neovascularizations (p < 0.05, p < 0.01, respectively), and a stronger expression of tenascin-C in the radius. The histological study showed a larger ECM area and less neointimal cell density in the radius than in the NIR. The RT-PCR and real-time PCR analysis revealed an enhanced expression of tanascin-C mRNA in the radius than in the NIR.

CONCLUSIONS

Increased production of ECM, especially tenascin-C, played a greater role in the neointimal formation in the radius stent than inflammation.

Tenascin-C, over expressed in lung cancer down regulates effector functions of tumor infiltrating lymphocytes

PURPOSE

Extracellular matrix (ECM) proteins play a significant role in the survival and metastasis of cancer cells. Tenascin-C (TN-C) is an extracellular matrix protein and its large isoform has been implicated in tumor progression. Goal of this study was to analyze the expression of the small and large isoforms of TN-C in non-small cell lung cancer (NSCLC) and determine its functional significance.

EXPERIMENTAL DESIGN

TN-C expression was studied in tumor and non-tumor tissue of patients with NSCLC at the mRNA and protein level. Immunomodulatory properties of the large isoform of TN-C were analyzed by determining its effect on lymphocyte proliferation and cytokine secretion by tumor-infiltrating lymphocytes (TIL).

RESULTS

Quantitative real-time PCR analysis showed an eight-fold increase in the amount of large isoform in cancer cells compared to adjacent normal tissue. Expression at the protein level by Western blot analysis using a murine monoclonal anti-TN-C antibody detected increased expression of the large isoform in the tumor tissue that was correlated with the development of recurrent disease. A 18-fold increase in the expression of the large TN-C isoform was observed in patients with recurrent NSCLC compared to non-recurrent NSCLC. Large isoform of TN-C significantly inhibited anti-CD3 and mitogen-induced proliferation of human peripheral blood lymphocytes and interferon-gamma production by TIL isolated from the lung cancer specimens.

CONCLUSIONS

Increased expression of TN-C observed at the site of tumor in NSCLC correlates with recurrence. TN-C inhibits TIL proliferation and cytokine thereby may promote tumor immune evasion and recurrence.

Transplantation of reconstructed human skin on nude mice: a model system to study expression of human tenascin-X and elastic fiber components

Tenascin-X is a large extracellular matrix protein that is widely expressed in connective tissues during development and in the adult. Genetically determined deficiency of tenascin-X causes the connective tissue disease Ehlers-Danlos syndrome. These patients show reduced collagen density and fragmentation of elastic fibers in their skin. In vitro studies on the role of tenascin-X in elastic fiber biology are hampered because monolayers of fibroblasts do not deposit tenascin-X and elastic fibers into the extracellular matrix. Here, we applied an organotypic culture model of fibroblasts and keratinocytes to address this issue. We investigated the deposition of tenascin-X and elastin into skin-equivalent in vitro and also in vivo after transplantation onto immunodeficient mice. Whereas tenascin-C and fibrillin-1 were readily expressed in the skin-equivalents before transplantation, tenascin-X and elastin were not present. Three weeks post-grafting, a network of elastin was observed that coincided with the appearance of tenascin-X. At the ultrastructural level, microfibrils were observed, some of which were associated with elastin. Transplanted skin-equivalents containing tenascin-X-deficient fibroblasts showed deposition of immunoreactive elastin in similar quantities and distribution as those containing control fibroblasts. This suggests that tenascin-X is important for the stability and maintenance of established elastin fibers, rather than for the initial phase of elastogenesis. Thus, the transplantation of reconstructed skin on nude mice allows the study of tenascin-X and elastin expression and could be used as a model system to study the potential role of tenascin-X in matrix assembly and stability.

Clinical and histopathological characterization of cutaneous melanomas in the melanoblastoma-bearing Libechov minipig model

Spontaneous animal tumors appear to be highly suitable models to study human oncology and cancer therapy. The aim of this study was to characterize the clinical and histological features of hereditary melanocytic lesions found in the French herd of melanoblastoma-bearing Libechov minipigs (MeLiM) and their Duroc crossbreeds. Clinically, we discriminated between three types of melanocytic skin lesions, which offer a lesion continuum from lentigo to metastatic melanomas. More than 70% of these lesions appear on piglets before they are 3 months old and preferentially on homogeneous black coat piglets. The incidence of melanoma reaches 50% in MeLiM. Most of the highly invasive melanomas regressed spontaneously in the first year of the piglet's life and the regression was followed by hair, skin and iris depigmentation. A histopathological study was conducted according to the human melanoma classification. Except for lentigo maligna, we observed the three main types of human melanoma in swine [superficial spreading melanoma (SSM), nodular or unclassified melanoma] with an excess of SSM (59-67%). The histological events leading to total spontaneous regression are chronologically described. The genetic predisposition, the high incidence of melanoma, the clinical and histopathological features similar to the human disease and the high rate of spontaneous regression offer an opportunity to use this model for studying genetic events controlling melanoma development and regression and the biological mechanisms involved in oncogenesis and anti-cancerous self-defense.

Identification of five chromosomal regions involved in predisposition to melanoma by genome-wide scan in the MeLiM swine model

In human familial melanoma, 3 risk susceptibility genes are already known, CDKN2A, CDK4 and MC1R. However, various observations suggest that other melanoma susceptibility genes have not yet been identified. To search for new susceptibility loci, we used the MeLiM swine as an animal model of hereditary melanoma to perform a genome scan for linkage to melanoma. Founders of the affected MeLiM stock were crossed with each other and with healthy Duroc pigs, generating MeLiM, F1 and backcross families. As we had previously excluded the MeLiM CDKN2A gene, we paid special attention to CDK4 and MC1R, as well as to other candidates such as BRAF and the SLA complex, mapping them on the swine radiation hybrid map and/or isolating close microsatellite markers to introduce them into the genome scan. The results revealed, first, that swine melanoma was inherited as an autosomal dominant trait with incomplete penetrance, preferably in black animals. Second, 4 chromosomal regions potentially involved in melanoma susceptibility were identified on Sus Scrofa chromosomes (SSC) 1, 2, 7 and 8, respectively, in intervals 44-103, 1.9-18, 59-73 and 47-62 cM. A fifth region close to MC1R was revealed on SSC 6 by analyzing an individual marker located at position 7.5 cM. Lastly, CDK4 and BRAF were unlikely to be melanoma susceptibility genes in the MeLiM swine model. The 3 regions on SSC 1, 6 and 7, respectively, have counterparts on human chromosomes (HSA) 9p, 16q and 6p, harboring melanoma candidate loci. The 2 others, on SSC 2 and 8, have counterparts on HSA 11 and 4, which might therefore be of interest for human studies.

A mouse model of uterine leiomyosarcoma

We are using an approach that is based on the cre/loxP recombination process and involves a binary system of Cre-producing and Cre-responding transgenic mice to achieve ubiquitous or tissue-specific expression of oncoproteins. To develop mouse models of tumorigenesis, Cre-producers are mated with responder animals carrying a dormant oncogene targeted into the 3' untranslated region of the locus encoding cytoplasmic beta-actin (actin cassette). Production of oncoprotein from a bicistronic message is accomplished in bitransgenic progeny by Cre-mediated excision of a segment flanked by loxP sites that is located upstream from the oncogenic sequence. Widespread Cre-dependent activation and expression of an actin-cassette transgene encoding the T antigens of the SV40 early region (SVER) commencing in embryos was compatible with normal development and did not impair viability. However, at approximately 3 months of age, all female animals developed massive uterine leiomyosarcomas, whereas practically all males exhibited enormously enlarged seminal vesicles because of pronounced hyperplasia of the smooth muscle layers. In addition, because of smooth muscle hyperproliferation, marked dilation of the gallbladder was observed in mice of both sexes. To begin exploring aberrant signaling events in the SVER-triggered tumorigenic pathways, we analyzed the expression profile of leiomyosarcomas by DNA microarray analysis.

CDKN2A region polymorphism and genetic susceptibility to melanoma in the melim swine model of familial melanoma

Some herds of miniature swine are genetically predisposed to cutaneous melanoma. To test if swine melanoma susceptibility could be linked to the CDKN2A gene, which is involved in a proportion of 9p21-linked human familial melanoma, we performed a genetic analysis of miniature pigs of the MeLiM strain. F(1) and backcross animals were generated by crossing 1 MeLiM boar with healthy Duroc sows. We isolated the swine CDKN2A gene and characterized a linked informative microsatellite marker, the S0644 marker. Using this marker and 2 flanking markers, we analyzed the segregation of the CDKN2A gene in a 3-generation pedigree. Allelic association, linkage analysis and haplotype analysis of these data led to exclusion of the CDKN2A gene as a candidate for melanoma susceptibility. Nonetheless, this analysis suggests an association with the swine 1q25 chromosomal region, which is homologous to the human 9p21 region.

Invasion of melanoma in double knockout mice lacking tenascin-X and tenascin-C

The roles of extracellular matrix glycoproteins belonging to the tenascin family in the regulation of tumor cell proliferation, invasion, and metastasis are not known. To address this issue, we generated tenascin-X (TNX) and tenascin-C (TNC) double knockout mice and compared findings in these mice with those in single knockout (TNX + / + TNC - / - and TNX - / - TNC + / +) mice. We investigated the proliferation and invasion of B16-BL6 melanoma cells after these cells had been injected into the footpads of mice in each group. The primary tumor size and invasion to the ankle adjacent to the primary tumor site were examined at 35 days after injection of the melanoma cells. The primary tumor size in TNX - / - TNC + / + mice was significantly larger than that in wild-type mice, but those of TNX + / + TNC - / - and double knockout mice were comparable to that in the wild-type mice. On the other hand, invasion to the ankle was obviously promoted in TNX - / - TNC + / + and double knockout mice compared with that in the wild-type mice, but invasion to the ankle in TNX + / + TNC - / - mice was only slightly promoted. Gelatin zymography confirmed increased matrix metalloproteinase (MMP)-9 activity in the dorsal skin of TNX - / - TNC + / +, TNX + / + TNC - / - and double knockout mice. However, the amounts of MMP-9 mRNA in the dorsal skins of all mice were almost the same, indicating that the increased activity of MMP-9 in the single and double knockout mice is regulated at the MMP-9 processing level. These results indicate that MMP-9 is activated in all TN-deficient mice, but that TNX exerts a greater effect on tumor invasion than does TNC.

Tumour invasion and metastasis are promoted in mice deficient in tenascin-X

BACKGROUND

Tenascin-X (TNX) is a member of the tenascin family of large oligomeric glycoproteins of the extracellular matrix (ECM). To determine whether TNX plays a part in tumour invasion and metastasis and to disclose its normal physiological role, we disrupted its gene in mouse embryonic stem cells by homologous recombination and created mice deficient in TNX.

RESULTS

TNX-null mutant (TNX-/-) mice arose at normal frequency and showed no obvious defects during their adult life. However, when TNX-/- mice were subcutaneously inoculated in foot-pads with a highly invasive and metastatic cell line, B16-BL6 melanoma cells, the primary tumour size at 30 days after inoculation in the TNX-/- mice had increased by 1.2-fold compared with that in wild-type mice, and the invasion to the ankle and pulmonary metastasis in TNX-/- mice were also augmented by 2.2-fold and 6.8-fold, respectively, compared to those in wild-type mice. To disclose the molecular mechanism(s) of the promotion of tumour invasion and metastasis in TNX-/- mice, we measured the protein levels of matrix metalloproteinases (MMPs), which are recognized as playing a key role in these events, in the foot-pad homogenates of TNX-/- mice prior to the inoculation of melanoma cells. Gelatin zymography showed that the activities of proMMP-2, active MMP-2 and proMMP-9 were significantly higher in TNX-/- mice than in wild-type mice. Furthermore, a Northern blot analysis demonstrated that this increased activity of MMP-2 in TNX-/- mice was due to the induced expression of MMP-2 at the transcriptional level. The elevated expression of MMP-2 and MMP-9 resulted in decreased laminin levels, to less than half that of wild-type mice in the homogenates of TNX-/- mice.

CONCLUSIONS

TNX deficiency led to an increase in the production of MMPs, and the increased activity of MMPs may result in the degradation of laminin. Consequently, the melanoma cells inoculated in TNX-/- mice might facilitate invasion and metastasis. These results imply that TNX is required for impeding the invasion and metastasis of tumour cells.

The alternatively spliced domain TnFnIII A1A2 of the extracellular matrix protein tenascin-C suppresses activation-induced T lymphocyte proliferation and cytokine production

Several lines of evidences have suggested that T cell activation could be impaired in the tumor environment, a condition referred to as tumor-induced immunosuppression. We have previously shown that tenascin-C, an extracellular matrix protein highly expressed in the tumor stroma, inhibits T lymphocyte activation in vitro, raising the possibility that this molecule might contribute to tumor-induced immunosuppression in vivo. However, the region of the protein mediating this effect has remained elusive. Here we report the identification of the minimal region of tenascin-C that can inhibit T cell activation. Recombinant fragments corresponding to defined regions of the molecule were tested for their ability to inhibit in vitro activation of human peripheral blood T cells induced by anti-CD3 mAbs in combination with fibronectin or IL-2. A recombinant protein encompassing the alternatively spliced fibronectin type III domains of tenascin-C (TnFnIII A-D) vigorously inhibited both early and late lymphocyte activation events including activation-induced TCR/CD8 down-modulation, cytokine production, and DNA synthesis. In agreement with this, full length recombinant tenascin-C containing the alternatively spliced region suppressed T cell activation, whereas tenascin-C lacking this region did not. Using a series of smaller fragments and deletion mutants issued from this region, we have identified the TnFnIII A1A2 domain as the minimal region suppressing T cell activation. Single TnFnIII A1 or A2 domains were no longer inhibitory, while maximal inhibition required the presence of the TnFnIII A3 domain. Altogether, these data demonstrate that the TnFnIII A1A2 domain mediate the ability of tenascin-C to inhibit in vitro T cell activation and provide insights into the immunosuppressive activity of tenascin-C in vivo.