Tenascin in normal, reactive, hyperplastic, and neoplastic tissues: biologic and pathologic implications

Immunohistochemical Expression of Tenascin-C in Canine Meningiomas

In humans, tenascin-C (TN-C) expression has been detected in more aggressive neoplasms of the central nervous system, such as gliomas and meningiomas. No study has analyzed the immune expression of TN-C in canine meningioma. The current study aimed to investigate the immunohistochemical distribution of TN-C in different grades of canine meningiomas. Twenty-one cases of canine meningioma (12 grade I, 6 grade II, and 3 grade III) were analyzed. All samples were examined by immunohistochemistry with the following antibodies: TN-C, epithelial membrane antigen (EMA), Ki-67, pan-cytokeratin (Pan CK), and vimentin. The histopathological diagnosis of meningioma was reinforced with the positive labeling of vimentin (moderate to strong) and EMA (mild to moderate) in neoplastic cells in most cases, independently of its grade or subtype. The immunoreactivity of TN-C was irregular: mild in grade I, moderate in grade II, and moderate to severe in grade III neoplasms. Usually, immune positivity was observed in the stroma and perivascular space in all subtypes. In addition, the concentric whorls of neoplastic cells were labeled positive in some psammomatous and transitional meningiomas. The reaction to TN-C was more significant in grade II and III tumors. The immunohistochemical findings of the current study suggest that TN-C can act as a stromal marker, mainly in grade II or III meningiomas.

Tenascin-C: Friend or Foe in Lung Aging?

Lung aging is characterized by lung function impairment, ECM remodeling and airspace enlargement. Tenascin-C (TNC) is a large extracellular matrix (ECM) protein with paracrine and autocrine regulatory functions on cell migration, proliferation and differentiation. This matricellular protein is highly expressed during organogenesis and morphogenetic events like injury repair, inflammation or cancer. We previously showed that TNC deficiency affected lung development and pulmonary function, but little is known about its role during pulmonary aging. In order to answer this question, we characterized lung structure and physiology in 18 months old TNC-deficient and wild-type (WT) mice. Mice were mechanically ventilated with a basal and high tidal volume (HTV) ventilation protocol for functional analyses. Additional animals were used for histological, stereological and molecular biological analyses. We observed that old TNC-deficient mice exhibited larger lung volume, parenchymal volume, total airspace volume and septal surface area than WT, but similar mean linear intercept. This was accompanied by an increase in proliferation, but not apoptosis or autophagy markers expression throughout the lung parenchyma. Senescent cells were observed in epithelial cells of the conducting airways and in alveolar macrophages, but equally in both genotypes. Total collagen content was doubled in TNC KO lungs. However, basal and HTV ventilation revealed similar respiratory physiological parameters in both genotypes. Smooth muscle actin (α-SMA) analysis showed a faint increase in α-SMA positive cells in TNC-deficient lungs, but a marked increase in non-proliferative α-SMA + desmin + cells. Major TNC-related molecular pathways were not up- or down-regulated in TNC-deficient lungs as compared to WT; only minor changes in TLR4 and TGFβR3 mRNA expression were observed. In conclusion, TNC-deficient lungs at 18 months of age showed exaggerated features of the normal structural lung aging described to occur in mice between 12 and 18 months of age. Correlated to the increased pulmonary function parameters previously observed in young adult TNC-deficient lungs and described to occur in normal lung aging between 3 and 6 months of age, TNC might be an advantage in lung aging.

Chemical modification improves the stability of the DNA aptamer GBI-10 and its affinity towards tenascin-C

Aptamers are useful tools in molecular imaging due to their numerous attractive properties, such as excellent affinity and selectivity to diverse types of target molecules and biocompatibility. We carried out structure-activity relationship studies with the tenascin-C (TN-C) binding aptamer GBI-10, which is a promising candidate in tumor imaging. To increase the tumor targeting ability and nuclease resistance under physiological conditions, systematic modifications of GBI-10 with single and multiple 2'-deoxyinosine (2'-dI) or d-/l-isonucleoside (d-/l-isoNA) were performed. Results indicated that sector 3 of the proposed secondary structure is the most important region for specific binding with TN-C. By correlating the affinity of eighty-four GBI-10 derivatives with their predicted secondary structure by Zuker Mfold, we first validated the preferred secondary structure at 37 °C. We found that d-/l-isoNA modified GBI-10 derivatives exhibited improved affinity to the target as well as plasma stability. Affinity measurement and confocal imaging analysis highlighted one potent compound: 4A_L/26T_L/32T_L, which possessed a significantly increased targeting ability to tumor cells. These results revealed the types of modified nucleotides, and the position and number of substituents in GBI-10 that were critical to the TN-C binding ability. Stabilized TN-C-binding DNA aptamers were prepared and they could be further developed for tumor imaging. Our strategy to introduce 2'-dI and d-/l-isoNA modifications after the selection process is likely to be generally applicable to improve the in vivo stability of aptamers without compromising their binding ability.

Tenascin-C Is Associated with Cored Amyloid-β Plaques in Alzheimer Disease and Pathology Burdened Cognitively Normal Elderly

Tenascin-C (TN-C) is an extracellular matrix glycoprotein linked to inflammatory processes in pathological conditions including Alzheimer disease (AD). We examined the distribution of TN-C immunoreactivity (ir) in relation to amyloid-β (Aβ) plaques and vascular Aβ deposits in autopsy brain tissues from 14 patients with clinical and neuropathological AD and 10 aged-matched controls with no cognitive impairment; 5 of the controls had Aβ plaques and 5 did not. TN-C ir was abundant in cortical white matter and subpial cerebral gray matter in all cases, whereas TN-C ir was weak in blood vessels. In all cases with Aβ plaques but not in plaque-free controls, TN-C ir was detected as large (>100 µm in diameter) diffuse extracellular deposits in cortical grey matter. TN-C plaques completely overlapped and surrounded cored Aβ plaques labeled with X-34, a fluorescent derivative of Congo red, and they were associated with reactive astrocytes astrocytes, microglia and phosphorylated tau-containing dystrophic neurites. Diffuse Aβ plaques lacking amyloid cores, reactive glia or dystrophic neurites showed no TN-C ir. In cases with cerebral amyloid angiopathy, TN-C ir in vessel walls did not spread into the surrounding neuropil. These results suggest a role for TN-C in Aβ plaque pathogenesis and its potential as a biomarker and therapy target.

Breast cancer with neoductgenesis: histopathological criteria and its correlation with mammographic and tumour features

Introduction. Breast cancer with mammographic casting type calcifications, high grade DCIS with an abnormal number of ducts, periductal desmoplastic reaction, lymphocyte infiltration, and tenascin-C (TN-C) overexpression has been proposed to represent a more aggressive form of breast cancer and has been denominated as breast cancer with neoductgenesis. We developed histopathological criteria for neoductgenesis in order to study reproducibility and correlation with other tumour markers. Methods. 74 cases of grades 2 and 3 DCIS, with or without an invasive component, were selected. A combined score of the degree(s) of concentration of ducts, lymphocyte infiltration, and periductal fibrosis was used to classify cases as showing neoductgenesis, or not. Diagnostic reproducibility, correlation with tumour markers, and mammographic features were studied. Results. Twenty-three of 74 cases were diagnosed with neoductgenesis. The kappa value between pathologists showed moderate reproducibility (0.50) (95% CI; 0.41–0.60). Neoductgenesis correlated significantly with malignant type microcalcifications and TN-C expression (P = 0.008 and 0.04) and with ER, PR, and HER2 status (P < 0.00001 for all three markers). Conclusions. We developed histological criteria for breast cancer with neoductgenesis. Neoductgenesis, by our applied histopathological definition was related to more aggressive tumour biology and malignant mammographic calcifications.

Molecular recognition force spectroscopy study of the dynamic interaction between aptamer GBI-10 and extracellular matrix protein tenascin-C on human glioblastoma cell

Molecular recognition force spectroscopy (MR-FS) was applied to investigate the dynamic interaction between aptamer GBI-10 and tenascin-C (TN-C) on human glioblastoma cell surface at single-molecule level. The unbinding force between aptamer GBI-10 and TN-C was 39 pN at the loading rate of 0.3 nN sec⁻¹. A series of kinetic parameters concerning interaction process such as the unbinding force f(u) , the association rate constant k(on) , dissociation rate constant at zero force k(off) , and dissociation constant K(D) for aptamer GBI-10/TN-C complexes were acquired. In addition, the interaction of aptamer GBI-10 with TN-C depended on the presence of Mg²⁺. This work demonstrates that MR-FS can be used as an attractive tool for exploring the interaction forces and dynamic process of aptamer and ligand at the single-molecule level. As a future perspective, MR-FS may be used as a potential diagnostic and therapeutic tool by combining with other techniques.

Nucleic acid aptamers: clinical applications and promising new horizons

Aptamers are a special class of nucleic acid molecules that are beginning to be investigated for clinical use. These small RNA/DNA molecules can form secondary and tertiary structures capable of specifically binding proteins or other cellular targets; they are essentially a chemical equivalent of antibodies. Aptamers have the advantage of being highly specific, relatively small in size, and non-immunogenic. Since the discovery of aptamers in the early 1990s, great efforts have been made to make them clinically relevant for diseases like cancer, HIV, and macular degeneration. In the last two decades, many aptamers have been clinically developed as inhibitors for targets such as vascular endothelial growth factor (VEGF) and thrombin. The first aptamer based therapeutic was FDA approved in 2004 for the treatment of age-related macular degeneration and several other aptamers are currently being evaluated in clinical trials. With advances in targeted-therapy, imaging, and nanotechnology, aptamers are readily considered as potential targeting ligands because of their chemical synthesis and ease of modification for conjugation. Preclinical studies using aptamer-siRNA chimeras and aptamer targeted nanoparticle therapeutics have been very successful in mouse models of cancer and HIV. In summary aptamers are in several stages of development, from pre-clinical studies to clinical trials and even as FDA approved therapeutics. In this review, we will discuss the current state of aptamers in clinical trials as well as some promising aptamers in pre-clinical development.

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.

Tenascin-C enhances pancreatic cancer cell growth and motility and affects cell adhesion through activation of the integrin pathway

BACKGROUND

Pancreatic cancer (PDAC) is characterized by an abundant fibrous tissue rich in Tenascin-C (TNC), a large ECM glycoprotein mainly synthesized by pancreatic stellate cells (PSCs). In human pancreatic tissues, TNC expression increases in the progression from low-grade precursor lesions to invasive cancer. Aim of this study was the functional characterization of the effects of TNC on biologic relevant properties of pancreatic cancer cells.

METHODS

Proliferation, migration and adhesion assays were performed on pancreatic cancer cell lines treated with TNC or grown on a TNC-rich matrix. Stable transfectants expressing the large TNC splice variant were generated to test the effects of endogenous TNC. TNC-dependent integrin signaling was investigated by immunoblotting, immunofluorescence and pharmacological inhibition.

RESULTS

Endogenous TNC promoted pancreatic cancer cell growth and migration. A TNC-rich matrix also enhanced migration as well as the adhesion to the uncoated growth surface of poorly differentiated cell lines. In contrast, adhesion to fibronectin was significantly decreased in the presence of TNC. The effects of TNC on cell adhesion were paralleled by changes in the activation state of paxillin and Akt.

CONCLUSION

TNC affects proliferation, migration and adhesion of poorly differentiated pancreatic cancer cell lines and might therefore play a role in PDAC spreading and metastasis in vivo.

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.

Immunohistochemical expression of Tenascin in embryogenesis, tumorigenesis and inflammatory oral mucosa

OBJECTIVE

Tenascin is a large extracellular matrix glycoprotein that plays specific role in cell matrix interaction. This protein is mainly attracted because of its oncofetal predominance expression at epithelial-mesenchymal interaction and also been associated with inflammatory response. Thus the aim was to study the expression of Tenascin within the oral cavity in a developing tooth, normal oral mucosa, squamous cell carcinoma and inflammatory mucosa and further to compare its expression in inflammatory mucosa with that of squamous cell carcinoma.

DESIGN

A total numbers of 92 cases were included, with 22 being all morphological stages of developing tooth, 10 cases of normal oral mucosa, 30 cases each of inflammatory gingival hyperplasia and oral squamous cell carcinoma. The intensity and pattern of expression was assessed immunohistochemically using anti-human mouse monoclonal Tenascin antibody.

RESULTS AND CONCLUSION

Tenascin expression in developing tooth was seen mainly at epithelial-mesenchymal junctions, but temporally reduced at cap stage. In normal mucosa TN expression was restricted only at basement membrane zone. Inflammatory gingival hyperplasia intensity of expression was enhanced at the juxtraepithelial stroma and showed reticular pattern of expression. In oral squamous cell carcinoma, intensity of expression was seen in superficial front of the stroma and also around tumour islands with intraepithelial expression and predominantly showed fibrillar pattern of expression. Furthermore, Tenascin expression was noticed around neovascularization. Hence, there is a regulatory system in Tenascin expression and plays a vital role in embryogenesis, tumerogenesis and inflammation in remodelling the stroma for cell migration and also for healing.

Extracellular matrix composition reveals complex and dynamic stromal-epithelial interactions in the mammary gland

The mammary gland is an excellent model system to study the interplay between stroma and epithelial cells because of the gland's unique postnatal development and its distinct functional states. This review focuses on the contribution of the extracellular matrix (ECM) to stromal-epithelial interactions in the mammary gland. We describe how ECM physical properties, protein composition, and proteolytic state impact mammary gland architecture as well as provide instructive cues that influence the function of mammary epithelial cells during pubertal gland development and throughout adulthood. Further, based on recent proteomic analyses of mammary ECM, we describe known mammary ECM proteins and their potential functions, as well as describe several ECM proteins not previously recognized in this organ. ECM proteins are discussed in the context of the morphologically-distinct stromal subcompartments: the basal lamina, the intra- and interlobular stroma, and the fibrous connective tissue. Future studies aimed at in-depth qualitative and quantitative characterization of mammary ECM within these various subcompartments is required to better elucidate the function of ECM in normal as well as in pathological breast tissue.

Differential expression of tenascin-C in the developing human lung: an immunohistochemical study

Much of the specification for the basic embryonic body plan is the result of a hierarchy of developmental decisions at different developmental times. The extracellular matrix (ECM) appears to be a very dynamic structure during embryogenesis. One of the mesenchymal ECM proteins, tenascin, is reported to be transiently expressed during embryonic tissue development, and is absent or much reduced in most fully developed organs. The respiratory system is an outgrowth of the ventral wall of the foregut, and the epithelium of the larynx, trachea, bronchi and alveoli is of endodermal origin. The cartilaginous and muscular components are of mesodermal origin. The aim of this study was to investigate the role of tenascin-C (TNC) in the developing human lung, during the pseudoglandular, canalicular and saccular stage of lung maturation. Formalin-fixed, paraffin-embedded tissue from the lungs of 30 embryos (10 corresponding to the 10th to the 16th gestational week (pseudoglandular stage), 10 to the 17th to the 23rd gestational week (canalicular stage), and 10 to the 24th to the 27th gestational week (saccular stage), were investigated by conventional histology and immunohistology for the expression levels of TNC. The changes observed in the distribution patterns suggest that during embryogenesis, the rate of tenascin synthesis changes significantly. During the pseudoglandular stage, the density of cells expressing TNC was higher in the condensing mesenchyme surrounding the epithelial glands than in the epithelial cells, whereas the inverse result was observed during the canalicular stage. During the saccular stage the pattern of immunoreactivity with TNC was lower than those of the pseudoglandular and canalicular stage, either in epithelial or mesenchymal cells, but it was highly expressed in the basement membranes. This restricted spatiotemporal distribution suggests that tenascin has a key role (1) in mesenchymal tissue remodeling during the pseudoglandular stage, a period that describes the development of the complete bronchial tree and (2) on the epithelial cell shape and function during the canalicular stage, a period that describes the formation of pneumocytes type I and pneumocytes type II. The later, will produce the surfactant, a phospholipid-rich fluid capable of lowering surface tension at the air-alveolar interface. During the saccular stage, tenascin was present mainly in the basement membranes surrounding the acinar and vascular structures, indicating a supporting and mechanical role.

Histopathological changes and tumour necrosis factor-alpha, transforming growth factor-beta and tenascin expression in patients with primary type I membranoproliferative glomerulonephritis in remission

AIM

Primary type I membranoproliferative glomerulonephritis (MPGN) is a rare cause of glomerular disease with a high relapse rate and poor prognosis. The aim of this study was: (i) to evaluate the histopathological findings associated with remission; and (ii) to document the possible clinical and histopathological factors predicting relapses.

METHODS

Eleven type I MPGN patients (five men, six women; mean age, 38.8+/-13.5 years) who were in remission for at least 1 year after the cessation of immunosuppressive drugs were re-biopsied. The intensity of immunostaining for tumor necrosis factor (TNF)-alpha, transforming growth factor (TGF)-beta1, and tenascin was graded from 0 (no staining) to 3+ (maximum staining).

RESULTS

Mean baseline mesangial cellularity score and tubulointerstitial infiltration score were reduced and mesangial matrix expansion score was increased at protocol re-biopsies compared to baseline. The glomerular and tubulointerstitial staining scores for TGF-beta1 and tenascin were higher than that of baseline. Reduced tubulointerstitial TNF-alpha expression was found in re-biopsy specimens compared to baseline. Patients have been followed for a mean time of 51.5+/-22.2 months after the protocol biopsy. Eight patients had a relapse. Mesangial cellularity score and glomerular tenascin expression at re-biopsy specimens were higher in relapsed patients compared to those without a relapse.

CONCLUSION

Our study shows that mesangial cellularity and tubulointerstitial cell infiltration are reducing whereas mesangial matrix expansion, glomerular and tubulointerstitial TGF-beta1 and tenascin expression are increasing with remission. The higher mesangial cell proliferation and glomerular tenascin scores in remission are associated with the development of relapse.

Integrins as receptors for extracellular matrix proteins in human cornea

Extracellular matrix (ECM) proteins form distinct protein families that play a role during tissue maturation, wound healing and maintenance of tissue architecture. Recent studies show that there are tissue type-specific variations in their expression. ECM proteins function by complexing with each other and also by interacting with their cellular receptors, called integrins. Integrins are heterodimeric membrane glycoproteins that are partly cell type-specifically expressed in human tissues. Like other stratified epithelia, corneal epithelium expresses alpha 2 beta 1, alpha 3 beta 1, alpha 6 beta 1, 4, and alpha v beta 1 integrins that mediate attachment to the basement membrane and cell-cell interactions.

Epithelial tenascin predicts obliterative airway disease

BACKGROUND

Epithelial cell injury, inflammation, fibrosis and airway obliteration result in remodeling of terminal bronchi in post-transplant obliterative bronchiolitis. Tenascin as an extracellular matrix glycoprotein is expressed in several remodeling processes.

METHODS

Heterotopic bronchial allografts of pigs were studied to assess tenascin expression during development of post-transplant obliterative bronchiolitis. A total of 157 allografts or autograft controls were serially obtained 2 to 28 days after transplantation and processed for histology and immunocytochemistry for tenascin, CD4, CD8 and macrophages. Epithelial tenascin index was calculated by multiplying the percentage of positive cells by the grade of tenascin intensity (1 to 3).

RESULTS

Epithelial tenascin expression occurred during the initial ischemic damage to the respiratory epithelium. After partial recovery and before total epithelial loss and subsequent airway obliteration, tenascin expression peaked in allografts (p < 0.001). Epithelial tenascin index on Day 7 was predictive of subsequent epithelial damage, bronchial wall inflammation and the number of (CD4(+) and CD8(+)) cells, fibroproliferation, and obliteration of the bronchial lumen (R > or = 0.47, p < or = 0.01). Tenascin expression in the bronchial wall was more intense in allografts (p < 0.001), paralleling proliferation of fibroblasts and influx of inflammatory cells, and was predictive of inflammatory alterations also in the early obliterative lesions (R > or = 0.45, p < 0.05). Expression decreased during maturation of fibrosis (p < 0.05).

CONCLUSIONS

Epithelial tenascin was predictive of features observed in post-transplant obliterative bronchiolitis, demonstrating a role for tenascin in the development of obliterative bronchiolitis. Tenascin may have relevant properties in serving as a clinical marker for early obliterative bronchiolitis.

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

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

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

BACKGROUND

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Formation of cysts by alveolar type II cells in three-dimensional culture reveals a novel mechanism for epithelial morphogenesis

Many organs consist of a hollow cavity surrounded by a monolayer of epithelial cells. Despite their common structure, such organs form by diverse morphogenetic processes. Three-dimensional culture systems have been useful in analyzing the events. Most processes require a combination of cell proliferation and cell death to produce a hollow cavity. Here, we describe a new three-dimensional culture system in which primary human lung alveolar type II cells formed hollow epithelial cysts by a novel process. Individual cells moved, collided, and formed alveolar-like cysts without appreciable proliferation or apoptosis. The alveolar-like cysts consisted of a polarized monolayer of differentiated alveolar type II cells, which secreted surfactant into the central lumen. Blockage of beta1 integrin did not alter cell movement or collision, but it greatly reduced adhesion of cells after collision and subsequent formation of alveolar-like cysts. Treatment of preformed alveolar-like cysts with forskolin increased their diameter, possibly due to stimulation of fluid secretion into the lumen. We conclude that epithelial differentiation and cyst formation can occur without appreciable proliferation or apoptosis.

Tenascin expression in actinic keratosis

BACKGROUND

Tenascin is an extracellular matrix protein frequently expressed around neoplastic and non-neoplastic lesions of the skin. Actinic keratoses (AKs) are intraepidermal neoplastic lesions of the sun-exposed skin. They are classified according to the extension of dysplasia in four stages; they also present different histological varieties.

METHODS

We performed an immunohistochemical study using tenascin monoclonal antibody diluted 1 : 50 on 150 cases of AKs classified, respectively, in histotypes (38 hypertrophic, 18 atrophic, 21 bowenoid, 19 acantolytic, and 40 mixed) and in stages (27 stage I, 46 stage II, 42 stage III, and 35 stage IV; 14 in tumoral progression).

RESULTS

Tenascin positivity was observed in all cases at the dermal level close to the epithelial lesion. The intensity of reaction increased from stage I to stage IV and, of course, also in tumoral progression. Its expression was not related to the histotypes. In very few cases, the atypical keratinocytes were positive.

CONCLUSIONS

Tenascin expression in AKs is related to the stages of dysplasia. In fact, the immunostaining intensity corresponds to the degree of the dysplasia rather than the thickness of the involved epidermis. Tenascin plays a role in neoplastic progression working as an anti-adhesive factor.

An unexpected inverse correlation between soluble epidermal growth factor receptor and interleukin-6 in metastatic malignant melanoma patients

The exact role of the soluble form of epidermal growth factor receptor (sEGF-R) in melanoma disease remains to be determined. We focused this study on the detection of circulating levels of sEGF-R in metastatic malignant melanoma patients and on the possible relationship between sEGF-R and clinicobiological parameters including circulating interleukin-6 (IL-6) and survival. sEGF-R and IL-6 levels were determined using a highly sensitive enzyme-linked immunosorbent assay in serum from 75 metastatic malignant melanoma patients and 30 healthy controls. In our patients, median sEGF-R level was significantly elevated (P < 0.0001) compared with that of healthy controls (173.4 vs. 91.9 fm/ml). Age or sex was not associated with sEGF-R levels. Regarding tumor burden, in contrary to the detected IL-6 levels, we found that median sEGF-R levels were significantly (P = 0.045) lower in patients with high tumor burden (163 fm/ml) than in those with low tumor burden (193.8 fm/ml). An inverse correlation between IL-6 levels and sEGF-R was observed (r =-0.33; P = 0.040). No relationship between sEGF-R and time to progression or overall survival was observed while circulating IL-6 was found as a predictive factor of survival. Our results showed that sEGF-R level was elevated in metastatic malignant melanoma patients but not related to time to progression or survival and demonstrated an inverse correlation between sEGF-R and IL-6 levels. These findings imply a better understanding of EGF-R and IL-6 cross-talk function in melanoma.

Modulation of response to tumor therapies by the extracellular matrix

The composition of the extracellular matrix in tumors is vastly different from that found in the normal tissue counterparts. As the extracellular matrix can signal to cells via integrin binding and activation, which is known to modulate cell proliferation, survival and migration, it may influence the response of both tumor and endothelial cells to anticancer therapies. Certain tumor-associated extracellular matrix proteins have been shown to confer resistance to chemotherapeutic drugs, radiation and anti-angiogenic factors. The current literature regarding this phenomenon and the potential therapeutic modalities to overcome extracellular matrix-induced resistance will be discussed.

cDNA microarray analysis of cancer associated gene expression profiles in malignant peripheral nerve sheath tumours

BACKGROUND

Malignant peripheral nerve sheath tumour (MPNST) is a highly aggressive malignancy that arises within peripheral nerves, and is associated with poor prognosis. Little is known about the underlying biology of MPNST, especially the mechanisms involved in cell proliferation, invasion, or escape from apoptosis.

AIMS

To identify genes differentially expressed in MPNST compared with benign tumours, such as neurofibromas and schwannomas, by means of cDNA microarray analysis.

METHODS

Six MPNST cases and five benign cases (three schwannomas and two neurofibromas) were analysed.

RESULTS

Six genes (keratin 18, survivin, tenascin C, adenosine deaminase, collagen type VIa3, and collagen type VIIa1) were significantly upregulated in MPNST, whereas one gene, insulin-like growth factor binding protein 6, was downregulated in MPNST. Survivin and tenascin C expression was validated by reverse transcription polymerase chain reaction. Immunohistochemistry confirmed upregulation of survivin in MPNST at the protein level in six of eight cases compared with benign tumours. Tenascin C was also expressed at the invasive front and tumorous stroma in all MPNST cases. MPNST cells expressed tenascin C in four of nine cases.

CONCLUSIONS

Survivin and tenascin C may be associated with the malignant potential of MPNST and could be considered as potential therapeutic targets.

Targeting CK2 for cancer therapy

Protein kinase CK2 is a highly ubiquitous and conserved protein serine/threonine kinase that has been found to be involved not only in cell growth and proliferation, but also in suppression of apoptosis. CK2 is capable of dynamic intracellular shuttling in response to a variety of signals. It is localized in both the nucleus and cytoplasm in normal cells, but is particularly predominant in the nuclear compartment in cancer cells. CK2 has been found to be uniformly dysregulated in all the cancers that have been examined. Downregulation of CK2 by chemical or molecular methods promotes apoptosis in cells. We have shown that antisense CK2alpha is particularly potent in inducing apoptosis in cancer cells in culture as well as in xenograft models of cancer such as prostate cancer and squamous cell carcinoma of head and neck. The antisense CK2alpha oligodeoxynucleotide (ODN) mediates tumor cell death in a dose- and time-dependent manner such that at an appropriate concentration of the antisense, a complete resolution of the xenograft tumor is observed. Interestingly, normal and benign cells (in culture as well as in vivo) demonstrate a relative resistance to the antisense CK2alpha ODN treatment, which raises the possibility of a significant therapeutic window for this therapy. Further, novel approaches such as the delivery of antisense CK2alpha ODN encapsulated in sub-50-nm tenascin nanocapsules have become available for its targeting specifically in cancer cells. Our studies minimize generally held concerns regarding suitability of CK2 as a target for cancer therapy and provide the first encouraging results for potential future application of this approach for cancer therapy.

Mutual paracrine effects of colorectal tumour cells and stromal cells: modulation of tumour and stromal cell differentiation and extracellular matrix component production in culture

Interactions of tumour and stromal cells influence tumour cell proliferation and differentiation, stromal cell phenotypic transdifferentiation and secretion of extracellular matrix (ECM) components. In this study, we established a monolayer and a three-dimensional cell-to-cell interaction model between canine mammary stromal cells and human colonic carcinoma cell lines (Caco-2 and HT-29) to investigate mutual paracrine effects of tumour cells and stromal cells on (i) tumour cell differentiation, (ii) production of ECM components and (iii) phenotypic transdifferentiation of stromal cells. We showed that when Caco-2 or HT-29 cells are cultured in collagen gels, they form a few small solid cell clusters with no lumina, but when cocultured with stromal cells, the tumour cells formed glandular structures with central lumina. This fibroblast-induced organization and differentiation of Caco-2 cells (not HT-29 cells) appeared to be mediated by transforming growth factor-beta (TGF-beta). Culturing of stromal cells, Caco-2 cells or HT-29 cells alone in both monolayers and gels resulted in weak tenascin-C expression in stromal cells and HT-29 cells and no expression in the Caco-2 cells. Coculturing of stromal cells with tumour cells resulted in increased tenascin-C expression in the stromal cells and HT-29 cells and induced expression of tenascin-C in the Caco-2 cells. This induction and increased expression of tenascin-C appeared to be mediated by TGF-beta. Culturing of stromal cells, Caco-2 cells or HT-29 cells alone on monolayers and in gels resulted in a weak expression of chondroitin sulfate (CS), chondroitin-6-sulfate (C-6-S) and versican in stromal cells and no expression in Caco-2 and HT-29 cells. Coculturing of stromal cells with tumour cells on monolayers and in gels resulted in increased CS, C-6-S and versican expression in stromal cells. This tumour cell-induced expression of CS, C-6-S and versican appeared to be mediated by TGF-beta and platelet-derived growth factor (PDGF). Coculturing of Caco-2 and HT-29 and stromal cells promoted the transdifferentiation of stromal cells into myofibroblasts, and this appeared to be mediated by TGF-beta. These results suggest that TGF-beta and PDGF are part of a paracrine system involved in stromal-epithelial cell interaction important in stromal cell differentiation and ECM component production.

Prognostic and predictive markers in canine tumours: rationale and relevance. A review

Cancer is one of the most common causes of death in dogs. The availability of multiple treatment modalities and novel therapeutic targets make the correct diagnosis, prognostic stratification, and the identification of treatment effect predictive factors an issue of major debate in cancer management. Selection of high and low risk patients and the type of systemic or local treatment is important in cancer management. The search for better prognostic markers and predictive factors is now focused on the molecular mechanisms which underlie tumour behaviour, such as altered cell cycle progression, proliferation, apoptosis, and angiogenesis. The ultimate goal is to identify reliable markers that can accurately diagnose and stage a tumour and predict tumour's clinical behaviour, prognosis and response to therapy. In this review, the current state of prognostication in canine tumours and promising new molecular markers are discussed. The markers are allocated to four groups according to their function: (i) proliferation markers, (ii) apoptosis, (iii) extracellular matrix and cell adhesion molecules, (iv) angiogenesis and (v) cell cycle regulators. Clinicopathological factors and histopathological grading remain the most practical parameters in decision-making. Although experimental research has shown that molecular markers have a good potential to be used as diagnostic, prognostic or predictive markers in canine tumours, insufficient evidence exists on their efficacy for routine use in veterinary oncology.

The phosphorylated form of connexin43 is up-regulated in breast hyperplasias and carcinomas and in their neoformed capillaries

We applied an antiserum (SA226P) specifically recognizing the phosphorylated form of connexin43 (P-Cx43) to human breast samples including normal breast samples, with fibrocystic disease (FCD), fibroadenomas (FA), in situ and infiltrating carcinomas of all major types, and miscellaneous extramammary tumors. The findings were compared with those obtained with commercial antisera recognizing all Cx43 forms (pan-Cx43). A subset of samples was stained for Her2-neu and p44/42 to mitogen-activated protein kinase. Paraffin step sections were used. Immunoblots were performed on frozen samples of a representative subset of cases. In the normal breast, FCD, and FA, SA226P stained strongly and extensively most myoepithelial cells (MECs); luminal cells remained unstained. In proliferative FCD and some cellular FA, SA226P stained MEC and the capillary endothelium (CE). In ductal and lobular in situ carcinomas, SA226P reacted strongly and diffusely with the remaining MEC, the CE, and the transformed luminal cells. SA226P stained all infiltrating carcinomas except the tubular variant. In all breast carcinomas, the CE within and adjacent to tumors and some myofibroblasts stained with SA226P. By contrast, pan-Cx43 stained weakly and sporadically the MEC and rare samples of invasive carcinomas. Notably, Mab p44/42 reacted in parallel with the samples stained with SA226P, whereas reactions with Her2 were negative. Immunoblot findings paralleled those obtained immunohistochemically. We conclude that P-Cx43, restricted to MEC in the normal breast, is up-regulated in the same cells in hyperplasias and dysplasias and FA and is strongly up-regulated in invasive carcinomas. Notably, in some proliferative FCD and in most in situ and infiltrating carcinomas, P-Cx43 is strongly expressed in CE within and adjacent to the lesions but not away from them. These findings were paralleled by the strong nuclear reactions noted with Mab p44/42. These phenomena, although not exclusive to malignancy, are particularly conspicuous in breast carcinomas and seemingly reflect active proliferation associated with abnormal gap junctional intercellular communication.

Mammary ECM composition and function are altered by reproductive state

To address whether reproductive state alters mammary gland extracellular matrix (ECM) composition and function, ECM was isolated from nulliparous, pregnant, lactating, involuting, and regressed rat mammary glands. The ECM composition of fibronectin, tenascin, laminin, clusterin, and MMPs was found to vary dramatically with reproductive state. In 3-dimensional (3-D) culture, we identified novel effects of these endogenous mammary matrices on mammary epithelial cells. Specifically we found that (1) matrix isolated from nulliparous animals promoted the formation of epithelial ducts with bifurcation, (2) matrix isolated from mid-involuting mammary glands induced cell death, (3) matrix isolated from late-stage involuting glands restored glandular development, while (4) matrix isolated from parous animals restricted glandular morphogenesis. Our data were consistent with mammary gland ECM facilitating epithelial cell proliferation, differentiation, death, and glandular reorganization that occur during the pregnancy and involution cycle. Further, we show that the parous gland has persistent changes in ECM function. Cumulatively, our data demonstrated that the microenvironment of the normal adult mammary gland is highly plastic, which has important implications for mammary tumor cell progression and dormancy. These data also raised the possibility of targeting mammary matrix production with preventive or therapeutic interventions.

Tenascin C expression is upregulated in pancreatic cancer and correlates with differentiation

BACKGROUND

Tenascin C is a large, hexameric, extracellular matrix protein that is present during embryonic development but essentially absent in adult tissues. It is involved in remodelling processes, such as wound healing and tumour development. Tissue expression of tenascin C correlates with prognosis in colorectal, cervical, and breast cancer and in carcinoma of the papilla of Vater.

AIM

To study the expression of tenascin C in pancreatic cancer and to compare the staining results with the patients' clinicopathological data.

MATERIAL AND METHODS

Formalin fixed, paraffin wax embedded specimens from 146 patients with pancreatic adenocarcinoma were stained with an anti-tenascin C monoclonal antibody.

RESULTS

Tenascin C immunoreactivity was seen in most samples of pancreatic carcinoma: staining was weak in 72 (49%), moderate in 52 (36%), strong in 10 (7%), and negative in 12 (8%) samples. Tenascin C expression correlated with age (< or = 66 v >66 years) and poor differentiation (grades 1-2 v 3). There was no correlation between tenascin C expression and survival, clinical stage, tumour size, nodal status, distant metastasis, tumour location, or sex.

CONCLUSION

Tenascin C expression was increased in most pancreatic carcinomas, but contrary to the results in other cancers, it is not a prognostic factor in pancreatic cancer.

Glomerular Capillary Tenascin Staining in Renal Allografts and Its Correlation with Capillary Loop ‘Double Contours’, Proteinuria and Graft Outcome

BACKGROUND

Glomerular capillary injuries result in proteinuria, previously reported to be a risk factor for renal allograft dysfunction. According to the Banff 97 Working Classification of Renal Allograft Pathology, 'double contours' in glomerular capillary loops (GC-DC) were suggested to be most specific for chronic transplant glomerulopathy. Tenascin-C (TN), a component of extracellular matrix, is known to be overexpressed in various conditions.

METHODS

TN immunostaining was performed by the labeled streptavidin biotin method. The correlations between glomerular capillary TN (GC-TN) and proteinuria, and between GC-DC and GC-TN, were studied in 27 biopsies showing chronic allograft nephropathy (CAN) lesions. In 14 patients (serum creatinine <2.0 mg/dl at biopsy), graft outcome was studied. Graft function 3 years after biopsy was classified as stable or deteriorated; the term 'deteriorated' was used if serum creatinine had increased 20% over baseline, or if the patient required dialysis.

RESULTS

In CAN, GC-TN correlated with GC-DC. Proteinuria in patients with intense GC-TN tended to increase during 1 year after biopsy. In graft outcome analysis, GC-TN was significantly lower in stable grafts than in deteriorated ones. Furthermore, all 3 patients demonstrating weak GC-TN without GC-DC returned to dialysis.

CONCLUSION

TN immunostaining is a sensitive method to detect glomerular capillary injury with a predictive value for renal allograft dysfunction.

Tenascin-C in primary malignant melanoma of the skin

AIMS

To investigate the expression and the prognostic role of glycoprotein Tenascin-C (Tn-C) in primary melanoma of the skin.

METHODS AND RESULTS

The immunohistochemical expression of Tn-C was studied in 98 primary melanomas and related to inflammation, invasion, and patient outcome. Patients were followed up for disease recurrence for 0.04-7.4 years (median 3.9) and for survival for 0.5 to 12.1 years (median 9.3). The expression of Tn-C was evaluated for each tumour invasion border; the stromal and intracytoplasmic Tn-C of the melanoma islets were also recorded. Tn-C is widely expressed in primary melanoma samples, the staining pattern varying from focal to diffuse in different parts of the tumour. No correlation existed between intensity of Tn-C staining and inflammation. No stromal Tn-C was detected at the upper dermal lateral border in 12 patients, nor at the deep, dermal or subcutaneous border in 14 patients. These patients showed better disease-free survival (DFS) than did those cases with focal or diffuse staining (P = 0.06, P = 0.05). Also, absence of intracytoplasmic Tn-C was a beneficial prognostic factor for DFS (P = 0.04). In multivariate analysis, tumour ulceration and intracytoplasmic Tn-C expression of melanoma cells were independent adverse prognostic factors for DFS.

CONCLUSIONS

In primary melanoma of the skin, absence of Tn-C in the stroma of invasion fronts and within tumour cells seems to be related to a more benign disease behaviour with a lower risk of developing metastases.

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

AIMS

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Increased postoperative concentrations of tenascin-C in wound fluid

BACKGROUND

Tenascin-C (Tn-C) is the most studied member of a family comprising large oligomeric glycoproteins in the extracellular matrix. The function of Tn-C still is unclear, and the levels of Tn-C in human wound fluid have not been studied.

METHODS

The participants in this study were 24 patients referred for elective major gastrointestinal surgery. Concentrations of Tn-C and procollagen propeptides type 1 and type 3 in serum and wound fluid were measured after surgery.

RESULTS

In wound fluid, Tn-C was present on postoperative day 1, and the concentration increased from day 5 up to day 7.

CONCLUSIONS

The concentration of Tn-C increases postoperatively in wound fluid. The concentration of Tn-C in wound fluid is markedly higher than that of serum. The differences in expression between Tn-C and the procollagen propeptides may reflect different tasks of these extracellular matrix proteins.

Expression of tenascin-C in various human brain tumors and its relevance for survival in patients with astrocytoma

BACKGROUND

Tenascin-C (TN-C), a large extracellular matrix (ECM) glycoprotein with a molecular weight of 180-250 kilodaltons, is present in several normal adult tissues. TN-C is up-regulated during embryogenesis, in wound healing, and in tumor tissues. Glioblastoma multiforme (GBM) is the most frequent and malignant astrocytic tumor comprised of poorly differentiated, neoplastic astrocytes. Recently, TN-C-based radioimmunotherapy was administered to patients with GBM.

METHODS

In the current study, the authors used immunohistochemistry to conduct a systematic investigation of TN-C distribution patterns in normal human brain tissue and in a large variety of brain tumors (n = 485 tumors). Immunoreactivity for TN-C was assessed with regard to its localization within tumor cells, blood vessels, and ECM using three different monoclonal antibodies (clones BC2, BC4, and TN2).

RESULTS

In control human brains, a significant difference was noted in the expression of TN-C when comparing gray with white matter using either Western blot analysis or immunohistochemistry. TN-C was found in the white matter of the frontal, temporal, parietal, and occipital lobes and in the hippocampus, where the immunoreaction was especially strong in the hippocampal formation. In 181 astrocytomas of different grades (World Health Organization [WHO] Grade 2-4), TN-C immunopositivity was seen to varying degrees in the cellular and stromal components of the tumor and in tumor-associated vessels. Glioblastomas (n = 113 tumors) showed strong immunopositivity in the vessels and moderate immunopositivity of the ECM. A statistically significant reduction of TN-C immunopositivity in tumor-associated vessels or ECM was observed in anaplastic astrocytomas (WHO Grade 3) compared with GBM (WHO Grade 4). A Kaplan-Meier analysis showed that patients who had GBM lesions that lacked TN-C immunopositivity in the ECM had a significantly longer survival (median, 28 months; standard error, 7.8 months) (n = 12 patients) compared with patients who had GBM lesions with TN-C immunopositivity (median, 12 months; standard error, 1.6 months) (n = 87 patients). In meningiomas (n = 24 tumors), the neoplastic cells, the ECM of the tumor, and the vessels were TN-C negative. In schwannomas (n = 31 tumors), the tumor cells were TN-C negative; whereas, in > 50% of tumors, the vessels and the ECM of regressively altered tumor areas were positive. In metastatic carcinomas (n = 53 tumors), the tumor cells were negative; seldom were vessels stained positive for TN-C. Focal areas of the ECM, often accompanied with fibrotic changes, were immunopositive for TN-C.

CONCLUSIONS

The most constant TN-C immunopositivity was noted in the ECM of the fibrotic stroma in highly malignant brain tumors and along the tumor border, especially in high-grade astrocytomas. The current results suggest that TN-C expression may be correlated with the grade of malignancy in astrocytic tumors and that the presence or absence of TN-C expression in the stroma of astrocytic tumors may play a not yet clearly understood role in shortening or prolonging, respectively, the survival of patients.

PAS inclusions, immunoreactive tenascin and proliferative activity in low-grade chondrosarcomas

To distinguish between chondrosarcoma (grade 1--borderline histology) and enchondroma, we examined six chondrosarcomas (grade 1--borderline histology) which looked like benign lesions. Their diagnosis, albeit based on clinical, radiologic and pathologic examinations, was not easily reached. Moreover, we examined six enchondromas and 11 chondrosarcomas, the diagnoses of which were straightforward. All cartilaginous tumors were studied, placing emphasis on PAS-positive intracytoplasmic globules. Anti-Ki67 proliferation-associated nuclear antigen antibody and tenascin antibody were applied. The following features were observed in low-grade chondrosarcomas: (1) masses of hyalin and/or myxoid cartilage invading spaces around the tumor, (2) host lamellar bone trabeculae surrounded by cartilage on all sides, (3) tumoral resorption of bone trabeculae. Intracytopasmic hyalin globules (ICG) were more frequently found in malignant than in benign neoplasm (p = 0.042). Moreover, tenascin matrix immunoreactivity was more likely to be observed in benign than in malignant neoplasm (p = 0.029). Ki67 immunoreactivity was more frequent in characterized than in low-grade chondrosarcomas or in enchondromas, where it was null (p = 0.0044).

Immunohistochemical localization of collagen type III and type IV, laminin, tenascin and alpha-smooth muscle actin (alphaSMA) in the human liver in peliosis

The expression of collagen types III and IV, laminin, tenascin, and hepatic stellate cells (HSCs) activation marker alphaSMA was evaluated immunohistochemically in the liver of three patients with non-bacilar peliosis. Peliosis was attributed to tuberculosis, endometriosis treated with anabolic androgenic steroids, and to pheochromocytoma. Ultrastructural examination of the lesions of the liver revealed cavities that were sometimes lined with sinusoidal endothelial cells or hepatocytic microvilli. In liver sinusoids around cavities, cystic dilatation of the space of Disse and an abundance of amorphous matrix were observed. At this location, HSCs were transformed into transitional cells or myofibroblasts. Extracellular matrix proteins (ECM) were increased in the dilated sinusoids around cavities perisinusoidally and in the wall of cavities themselves. AlphaSMA was also increased. Ultrastructural immunohistochemistry revealed strong intracellular deposits of collagen type IV, laminin, and alphaSMA in HSCs. Laminin immunoreactivity was also noted in the endocytic vesicles in the cytoplasm of a monocyte. These findings suggest that enhanced ECM accumulation and the transformation of HSCs into myofibroblasts constitute a secondary event in peliosis and an attempt of the liver to restrict and remove sinusoidal dilatation.

Tenascin expression in relation to stromal tumour cells in canine gastrointestinal epithelial tumours

The expression of tenascin, alpha-smooth muscle actin (alpha-SMA), desmin and vimentin was investigated immunohistochemically in the stroma of normal canine stomach, small intestine and colon, and in 30 epithelial tumours of the canine stomach, small intestine or colon. In addition, "co-localization" of tenascin and alpha-SMA was investigated by double immunohistochemistry. Tenascin was absent in the normal gastric mucosa but present in the normal intestine, with a gradual increase in immunolabelling intensity from the cryptal glands to the surface epithelium. Tenascin expression was greater in all adenomas and carcinomas than in normal tissues. Two different patterns of tenascin expression were observed in all carcinomas, irrespective of their site. In well-differentiated tumour regions of both gastric and intestinal tumours, a fibrillary sub-glandular expression was observed; in poorly differentiated tumour regions, however, the expression pattern was diffuse. Incomplete invasion of the muscularis mucosae was accompanied by thickening and increased tenascin expression. In normal stomach and intestines, alpha-SMA and desmin were demonstrated in pericryptal myofibroblasts and smooth muscle cells of the muscle layers. In colonic adenomas and gastric and intestinal carcinomas, alpha-SMA was demonstrated in all stromal cells surrounding tumour cells. In contrast to alpha-SMA labelling, desmin labelling was negative in tumour stromal cells (in both gastric and intestinal tumours), except in tumour regions close to the muscularis mucosae. This suggested that myofibroblasts in gastric and intestinal tumours originated from pre-existing fibroblasts, except in tumour regions close to the muscularis mucosae, where the myofibroblasts seemed to originate from smooth muscle cells of the muscularis mucosae. There was a strong co-localization of tenascin and alpha-SMA-expressing myofibroblasts, suggesting that myofibroblasts are responsible for tenascin secretion.

Over-expression of tenascin-C in malignant pleural mesothelioma

AIMS

Tenascin-C is an extracellular matrix glycoprotein known to have anti-adhesive characteristics and to be expressed in various human malignant neoplasms. We hypothesized that the expression of tenascin-C would be increased in human malignant pleural mesothelioma, and its accumulation associated with the prognosis of the patients with this disease.

METHODS AND RESULTS

Thirty-seven cases of mesothelioma were studied by immunohistochemically using a monoclonal antibody against tenascin-C, and with a semiquantitative scoring system for tenascin-C in different areas of the tumours. In 10 selected cases tenascin-C mRNA in-situ hybridization was also analysed. Since transforming growth factor-beta (TGF-beta) is known to induce both the synthesis of tenascin-C and the growth of mesotheliomas, an immunohistochemical analysis of TGF-beta 1, -beta 2 and -beta 3 was also performed. Normal pleura (n = 7) and metastatic pleural adenocarcinomas (n = 7) were used as controls. Tenascin-C protein was expressed in every histological subtype of malignant mesothelioma, being most prominent in the fibrotic stroma of a tumour, around tumour cells and at the invasive border, whereas tenascin-C mRNA was scarce in tumour cells. The patients with less immunohistochemical expression for tenascin-C tended to live longer (P = 0.028 by Fishers' exact probability test). All mesotheliomas showed positivity for at least one isoform of TGF-beta.

CONCLUSIONS

In conclusion, high expression of tenascin-C protein in malignant pleural mesotheliomas may play a role in its invasive growth, and might serve as a prognostic marker of the disease.

Interaction of nitric oxide and cell adhesion molecules after 24 hours of complete ureteric obstruction in the rats on a solitary kidney

We aimed to show whether the administration of exogenous L-Arg would alter the morphological, functional changes and interaction of nitric oxide and cell adhesion molecules such as tenascin and lectin after release of twenty-four hours complete ureteric obstruction in the solitary rat kidney tissue. Forty prepubertal Wistar-Albino rats were separated into 4 groups, each containing 10 rats. In the group 1 (Sham-control, n = 10), right nefrectomy was performed; the left ureter was visualized but not ligated. In the remaining 30 rats, the abdomen was opened and undergone right nephrectomy and the left ureter was completely obstructed. After 24 hours, thirty rats were divided as group 2, 3, and 4, each containing 10 rats. In-group 2, no drug treatments were given. In-group 3 L-Arg (L-arginine methyl ester) was infused immediately after abolishing ureteric obstruction. In-group 4 L-NAME was give separately during L-Arg administration during 30 minutes immediately after abolishing ureteric obstruction. Than, the animals were prepared for functional and histopathological studies. BUN value was decreased significantly in L-Arg group when compared with untreatment and L-NAME groups (p < 0.05, p < 0.001 respectively). Creatinine values were decreased in L-Arg group when compared with untreatment group (p < 0.002). Urine flow and urinary Na value was increased significantly in L-Arg group when compared to other obstruction groups (p < 0.001, p < 0.001). The increase in the number of macrophages in Untreated and L-NAME group were significant (p < 0.001, p < 0.001) when compared to L-Arg group. Immunohistochemical study showed that tenascin and lectin expression was severe in tubulus basal membrane of untreated and L-NAME treated rats. In L-Arg group, tenascin and lectin expression was moderate in tubulus membrane. Our results suggest that the administration of exogenous L-Arg protect the functional and degenerative effects of acute complete obstruction in the solitary kidney tissue of the rats. Nitric oxide cause these positive effects by decreasing preglomerular vascular resistance, regulation of neutrophil function and preventing the expression of cell adhesion molecules such as tenascin and lectin.

Degradation of extracellular matrix protein tenascin-C by cathepsin B: an interaction involved in the progression of gliomas

Degradation of extracellular matrix proteins by proteases such as the cysteine protease cathepsin B is critical to malignant progression. We have established that procathepsin B presents on the surface of tumor cells through its interaction with the annexin II tetramer [Mai et al., J. Biol. Chem. 275 (2000),12806-12812]. Cathepsin B activity can also be detected on the tumor cell surface and in their culture medium. Interestingly, the annexin II tetramer also interacts with extracellular matrix proteins, such as collagen I, fibrin and tenascin-C. Both cathepsin B and tenascin-C are expressed at high levels in malignant tumors, especially at the invasive edges of tumors, and are implicated in tumor angiogenesis. In this study, we report that tenascin-C can be degraded by cathepsin B in vitro. We demonstrate by immunohistochemistry that both cathepsin B and tenascin-C are expressed highly in malignant anaplastic astrocytomas and glioblastomas as compared to normal brain tissues. Interestingly, cathepsin B and tenascin-C were also detected in association with tumor neovessels. We suggest that interactions between cathepsin B and tenascin-C are involved in the progression of gliomas including the angiogenesis that is a hallmark of anaplastic astrocytomas.

Tenascin and proteoglycans: the role of tenascin and proteoglycans in canine tumours

Tenascin is a high molecular weight, extracellular matrix glycoprotein, subject to complex spatial and temporal patterns of expression during embryogenesis, wound healing and neoplastic processes. Proteoglycans are complex macromolecules, containing one or more glycosaminoglycans attached to a core protein, which are involved in cell-cell and cell-matrix interaction. Altered expression of both tenascin and proteoglycans has been found in tumours and expression of these two extracellular matrix proteins seems to be modulated in the same way in human and canine tumours. The quantitative and qualitative changes in tenascin and proteoglycan composition may significantly affect behaviour of tumour cells. While tenascin and proteoglycans have many biological functions likely to influence tumour development and progression, their exact role in regulation of tumour cell-cell interaction, proliferation, invasion and metastasis remains to be established. This review focuses on the role of tenascin and proteoglycans in neoplasia and recent developments in canine tumours.

Tenascin and beta 6 integrin are overexpressed in floor of mouth in situ carcinomas and invasive squamous cell carcinomas

Floor of the mouth squamous cell carcinomas exhibit many characteristics that suggest they represent a distinct biological subset within head and neck tumors. The features of preinvasive lateral intraepithelial spread, high rate of conversion of intraepithelial neoplasia to invasive carcinoma, and high incidence of occult metastases, suggest the importance of motility-associated proteins in the pathogenesis of these lesions. Two such proteins, tenascin and beta 6 integrin, are generally overexpressed in squamous carcinomas, and may play a central role in the invasive process of floor of the mouth lesions. The purpose of this study was to evaluate in situ and invasive squamous cell carcinomas from the floor of the mouth for the expression of tenascin and beta 6 integrin. Twenty lesions each of floor of the mouth in situ carcinomas and squamous cell carcinomas, and 10 normal controls were stained for tenascin and beta 6 using a standard immunohistochemical protocol for formalin-fixed specimens. Sections were assessed for staining intensity, pattern, and co-localization. Tenascin was highly expressed at the keratinocyte-connective tissue interface of both in situ and invasive carcinomas. beta 6 was expressed in basal keratinocytes of all in situ and invasive lesions, but was not evident in any of the control epithelia. There was no significant difference in staining of in situ and invasive carcinomas, but there was a significant difference in staining between these lesions and controls. Staining was colocalized in serial sections, supporting a receptor-ligand relationship. Both tenascin and beta 6 were weakly expressed in dysplastic areas adjacent to carcinomas suggesting that changes in the expression of these proteins occurs prior to the invasive phenotype. We conclude that tenascin and beta 6 are overexpressed in in situ and invasive floor of the mouth carcinomas, but that transgression of the basement membrane by neoplastic epithelial cells requires additional changes to the keratinocyte molecular profile.

Nup88 (karyoporin) in human malignant neoplasms and dysplasias: correlations of immunostaining of tissue sections, cytologic smears, and immunoblot analysis

Nuclear pore complexes (NPCs) are elaborate macromolecular structures that regulate the bidirectional nucleocytoplasmic traffic system. In vertebrate cells, NPCs include a family of 50 to 100 proteins termed nucleoporins (Nups). The 88-kD Nup has been found to be linked in a dynamic subcomplex with the oncogenic CAN/Nup214. Applying a polyclonal antiserum to Nup88 on paraffin sections, we found that it immunoreacts with numerous malignant neoplasms. All carcinomas reacted irrespective of site, type, or degree of differentiation; often, high-grade carcinomas stained more strongly and extensively. Some sarcomas (e.g., fibrosarcomas, leiomyosarcomas, liposarcomas, and rhabdomyosarcomas) reacted intensely; melanomas, gliomas, mesotheliomas, and malignant lymphomas also stained. In situ carcinomas of the colon, stomach, breast, and prostate stained convincingly, as did in situ melanomas; some samples of fetal tissues also reacted. Cytologic smears of some of the aforementioned tumors also stained. In selected samples, enhanced immunostaining of tissue sections and cytologic smears correlated strongly and consistently with immunoblot data. Immunoblots of the same tumors with antibodies to 2 other Nups (Nup214 and Nup153) showed no comparable enhancement. Therefore, it seems that in some malignant tumors, Nup88 overexpression is not parallelled by an overexpression of other Nups. Benign tumors, hyperplasias, and normal tissues showed weak and sporadic staining or absence of staining; immunoblots of the same samples yielded weak signals. Occasional highly proliferative hyperplastic-reactive processes showed focal staining. Thus, our correlative histologic, cytologic, and molecular data indicate that Nup88 may be viewed as a potentially useful, broadly based histodiagnostic and molecular marker of many malignancies and premalignant dysplasias, and further suggest that in some malignant tumors, Nup88 may be selectively overexpressed as compared with other Nups. Thus, we propose that Nup88 be designated as karyoporin.

Tenascin expression in normal, hyperplastic, and neoplastic endometrium

Tenascin (TN) is an extracellular matrix glycoprotein (ECM) that participates in embryogenesis and carcinogenesis. The aim of this study was to investigate immunohistochemically the expression of TN in the normal, hyperplastic, and neoplastic endometrium (endometrial adenocarcinoma). In the adenocarcinomas, the results were correlated with patient age, menopausal status, stage, grade, myometrial invasion, and vascular invasion. TN expression was studied in the following cases: proliferative endometrium (10 cases), early secretory endometrium (10), secretory endometrium (10), simple hyperplasia (15), complex hyperplasia (15), atypical hyperplasia (15), and endometrial adenocarcinomas (25). Staining of basal membranes and the cytoplasm of the stromal and epithelial cells was evaluated semiquantitatively. Positive staining was observed in the vascular and glandular basal membranes, stromal cells, and epithelial cells of proliferative, hyperplastic, and neoplastic endometrium. The difference in percentage of stained stromal cells between the neoplastic and the nonneoplastic (proliferative and hyperplastic) endometrium was significant (p<0.005). However, the percentage of stained epithelial cell area in hyperplasia was significantly higher than that of adenocarcinoma and functional endometrium (p<0.005). We conclude that TN is an extracellular matrix glycoprotein that plays a role in proliferation and possibly endometrial carcinogenesis.

Tenascin-C aptamers are generated using tumor cells and purified protein

Tenascin-C (TN-C) is an extracellular matrix protein that is overexpressed during tissue remodeling processes, including tumor growth. To identify an aptamer for testing as a tumor-selective ligand, SELEX (systematic evolution of ligands by exponential enrichment) procedures were performed using both TN-C and TN-C-expressing U251 glioblastoma cells. The different selection techniques yielded TN-C aptamers that are related in sequence. In addition, a crossover procedure that switched from tumor cell to purified protein selections was effective in isolating two high-affinity TN-C aptamers. When targeting tumor cells in vitro, the observed propensity of naive oligonucleotide pools to evolve TN-C aptamers may be due to the abundance of this protein. In vivo, TN-C abundance may also be well suited for aptamer accumulation in the tumor milieu. A size-minimized and nuclease-stabilized aptamer, TTA1, binds to the fibrinogen-like domain of TN-C with an equilibrium dissociation constant (K(d)) of 5 x 10(-9) m. At 13 kDa, this aptamer is intermediate in size between peptides and single chain antibody fragments, both of which are superior to antibodies for tumor targeting because of their smaller size. TTA1 defines a new class of ligands that are intended for targeted delivery of radioisotopes or chemical agents to diseased tissues.

Vitronectin in the cirrhotic liver: an immunomarker of mature fibrosis

Vitronectin (Vn) is a multifunctional plasma glycoprotein produced by hepatocytes. Vn has been studied extensively as a cell adhesion molecule. However, its localization in the hepatic extracellular matrix has received relatively little attention. Cryosections of 5 normal liver samples and of 20 specimens showing posthepatitic cirrhosis were stained by the avidin-biotin complex method with a well-characterized monoclonal antibody to Vn. The extent and intensity of immunostaining were assessed semiquantitatively (0, no staining; 1+, weak focal staining; 2+, strong focal staining; 3+, strong diffuse staining). Paraffin sections from the same samples were stained with Masson trichrome (MT) and Shikata orcein (Or) methods. Frozen samples from selected cases were analyzed by Western blotting. In the normal liver, 3+ staining was limited to portal vessels. The portal tract connective tissue showed minimal staining (0 to 1+). Cirrhotic septa showed strong staining (2+). Septa lacking significant inflammation and composed of dense connective tissue, as indicated by MT and Or stains, showed the strongest Vn reactions (3+). Immunoblotting data strongly correlated with Vn increase in cirrhotic livers. Vn immunoreactivity is markedly increased in the cirrhotic liver matrix, regardless of the documented decrease in plasma Vn. Binding to collagen, elastin, and proteoglycans is the current favored mechanism of Vn deposition in tissues. Previous studies in cirrhotic patients showed increased affinity of plasma Vn to collagen. Vn is also increased in aged skin, associated with dermal elastic fibers. In other tissues, Vn deposition reflects chronicity of injury. Therefore, Vn immunoreactivity in liver can be considered a marker of fibrosis, especially of chronic/mature fibrosis, paralleling previous observations on enhanced orcein staining of cirrhotic septa. Immunolabeling of biopsy specimens with Vn and tenascin, a marker of ongoing remodeling or recently formed fibrous tissue, could be diagnostically helpful.

Increased expression of tenascin in pheochromocytomas correlates with malignancy

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