Distribution of tenascin in oral premalignant lesions and squamous cell carcinoma

Differences in Extracellular Vesicle Protein Cargo Are Dependent on Head and Neck Squamous Cell Carcinoma Cell of Origin and Human Papillomavirus Status

To identify potential extracellular vesicle (EV) biomarkers in head and neck squamous cell carcinoma (HNSCC), we evaluated EV protein cargo and whole cell lysates (WCL) from HPV-positive and -negative HNSCC cell lines, as well as normal oral keratinocytes and HPV16-transformed cells. EVs were isolated from serum-depleted, conditioned cell culture media by polyethylene glycol (PEG) precipitation/ultracentrifugation. EV and WCL preparations were analyzed by LC-MS/MS. Candidate proteins detected at significantly higher levels in EV compared with WCL, or compared with EV from normal oral keratinocytes, were identified and confirmed by Wes Simple Western protein analysis. Our findings suggest that these proteins may be potential HNSCC EV markers as proteins that may be (1) selectively included in EV cargo for export from the cell as a strategy for metastasis, tumor cell survival, or modification of tumor microenvironment, or (2) representative of originating cell composition, which may be developed for diagnostic or prognostic use in clinical liquid biopsy applications. This work demonstrates that our method can be used to reliably detect EV proteins from HNSCC, normal keratinocyte, and transformed cell lines. Furthermore, this work has identified HNSCC EV protein candidates for continued evaluation, specifically tenascin-C, HLA-A, E-cadherin, EGFR, EPHA2, and cytokeratin 19.

Functions of Matricellular Proteins in Dental Tissues and Their Emerging Roles in Orofacial Tissue Development, Maintenance, and Disease

Matricellular proteins (MCPs) are defined as extracellular matrix (ECM) associated proteins that are important regulators and integrators of microenvironmental signals, contributing to the dynamic nature of ECM signalling. There is a growing understanding of the role of matricellular proteins in cellular processes governing tissue development as well as in disease pathogenesis. In this review, the expression and functions of different MP family members (periostin, CCNs, TSPs, SIBLINGs and others) are presented, specifically in relation to craniofacial development and the maintenance of orofacial tissues, including bone, gingiva, oral mucosa, palate and the dental pulp. As will be discussed, each MP family member has been shown to have non-redundant roles in development, tissue homeostasis, wound healing, pathology and tumorigenesis of orofacial and dental tissues.

Morphological Analysis of Elastic Fibers in Various Grades of Oral Squamous Cell Carcinoma and Epithelial Dysplasia Using Verhoeff-Van Gieson Stain

BACKGROUND

Oral squamous cell carcinoma (OSCC) is the sixth most common malignancy in India. The aggressiveness of OSCC is analyzed not only based on the dysplastic features and tumor infiltration pattern, but also by means of the stromal changes that pave the way for an invasion into the connective tissue. The role of elastic fibers in the progression of OSCC is still unknown because of sparse literature and the masking effect of overlying inflammatory cells and the lower number of elastic fibers in the lamina propria. The present study provides further insight into the qualitative assessment of elastic fibers in various grades of dysplasia and OSCC.

OBJECTIVES

To analyze the morphological changes exhibited by the elastic fibers in epithelial dysplasia and OSCC.

MATERIALS AND METHODS

Two sections were cut from each of 60 samples of varying grades of OSCC and 60 samples of varying grades of epithelial dysplasia followed by staining with hematoxylin and eosin and Verhoeff-Van Gieson stain.

RESULTS

Statistically significant results were obtained for qualitative analysis of elastic fibers. A change in density and orientation to overlying epithelium and tumor islands was seen on progressing from well-differentiated to poorly differentiated OSCC and in progressing grades of dysplasia.

CONCLUSION

The uniqueness of this study lies in the exploration of elastic fibers in dysplasia and well-differentiated OSCC, a less explored field. The study of the connective tissue stromal changes can be used as an adjunct to histological grading.

Tenascin-C and fibronectin expression divide early stage tongue cancer into low- and high-risk groups

Background:

Oral tongue squamous cell carcinoma (OTSCC) metastasises early, especially to regional lymph nodes. There is an ongoing debate on which early stage (T1-T2N0) patients should be treated with elective neck dissection. We need prognosticators for early stage tongue cancer.

Methods:

Mice immunisation with human mesenchymal stromal cells resulted in production of antibodies against tenascin-C (TNC) and fibronectin (FN), which were used to stain 178 (98 early stage), oral tongue squamous cell carcinoma samples. Tenascin-C and FN expression in the stroma (negative, moderate or abundant) and tumour cells (negative or positive) were assessed. Similar staining was obtained using corresponding commercial antibodies.

Results:

Expression of TNC and FN in the stroma, but not in the tumour cells, proved to be excellent prognosticators both in all stages and in early stage cases. Among early stages, when stromal TNC was negative, the 5-year survival rate was 88%. Correspondingly, when FN was negative, no cancer deaths were observed. Five-year survival rates for abundant expression of TNC and FN were 43% and 25%, respectively.

Conclusions:

Stromal TNC and, especially, FN expressions differentiate patients into low- and high-risk groups. Surgery alone of early stage primary tumours might be adequate when stromal FN is negative. Aggressive treatments should be considered when both TNC and FN are abundant.

Immunohistochemical analysis of tenascin expression in different grades of oral submucous fibrosis

Aim:

Tenascin, a glycoprotein, is one of the major constituents of extracellular matrix, which may function in organizing the stroma in normal and pathological conditions. The study aimed to correlate the structural organization of tenascin with the pathological progression of disease from early, moderate and advanced changes in oral submucous fibrosis (OSMF).

Study Design:

A retrospective cross-sectional immunohistochemical (IHC) analysis of OSMF cases was performed. Total 70 slide samples were prepared for the study from 35 formalin-fixed paraffin-embedded tissue blocks with 10 each from histologically proven and graded as early, moderate and advanced OSMF and 5 of normal oral mucosa. The IHC sections were analyzed for the intensity and pattern of tenascin expression at the junction of epithelium and connective tissue (ECJ) and deeper connective tissue (CT), as well as presence or absence of staining around inflammatory cells, fibroblast and endothelial cells using anti-human tenascin.

Result:

Most of the OSMF cases showed retention of antigen at ECJ and in deeper CT. Its expression varied in different grades as well as around inflammatory cells, fibroblast and endothelial cells in same tissue section. Highly significant P values of 0.001 and 0.003 were obtained for tenascin intensity and pattern, respectively, at ECJ in different OSMF grades. In addition, for the expression of tenascin pattern in deeper CT among different OSMF grades, a significant P value of 0.018 was obtained.

Conclusion:

A differential expression of tenascin was observed with the progression of disease. The expression of tenascin as bright and continuous deposition at ECJ in early and moderate stages of OSMF signifies either proliferative organization within the overlying epithelium or an epithelial-mesenchymal interaction. However, a weak immunoreactivity of tenascin at ECJ was observed in advanced stage of OSMF.

Immunoexpression of tenascin as a predictor of the malignancy potential of oral leukoplakia associated with a tobacco habit

Oral leukoplakia is a morphological alteration of tissue that is an early indicator for malignancy. Tenascin (TN) is a large hexameric extracellular matrix (ECM) protein with anti-adhesive properties that fosters cell migration during development, wound healing and tissue remodeling; it is present in small amounts in adult tissues. Overexpression of TN in a pathological condition may be either a cause or a consequence of the disease. We evaluated the efficacy of TN for early prediction of tobacco-associated oral cancers. We studied retrospectively 95 cases of oral leukoplakia, including mild, moderate and severe cases, using immunohistochemistry for TN. We evaluated the intensity, area and pattern of TN expression. Greater intensity and area of TN expression was observed in mild and severe dysplasia than in moderate dysplasia. Most cases showed a reticular pattern of expression, especially in mild and moderate dysplasia; a fibrillar pattern was more evident in severe dysplasia. We also observed homogeneous expression pattern in some cases. TN is a marker for dysplastic changes in epithelium and its expression may be helpful for predicting the malignancy potential of tobacco-associated oral leukoplakia.

Tenascin-C and carcinoma cell invasion in oral and urinary bladder cancer

Carcinoma invasion is a complex process regulated by genetic and epigenetic factors as well. A relevant supportive condition for cancer cell migration is the reorganization of the extracellular matrix (ECM), which is realized in an orchestrated multicellular manner including carcinoma cells and stromal fibroblasts. An important key player in the process of ECM reorganization is Tenascin-C (Tn-C). The molecule occurs as different isoforms generated by alternative splicing and de novo glycosylation. Large variants of Tn-C are abundantly re-expressed in the invasive front of many carcinoma types. A special role for initiating migration and accompanied epithelial to mesenchymal transition has been suggested. Here, we review the current knowledge concerning the tumor biological importance of Tn-C, the synthesis and alternative splicing during the invasive process in general, and give an overview on the impact of Tn-C in urothelial carcinoma of the urinary bladder (UBC) and oral squamous cell carcinoma (OSCC).

Molecular changes in invasive front of oral cancer

Treatment planning for oral squamous cell carcinoma (OSCC) is based on the clinical TNM (Tumor, Node and Metastasis) classification. This system operates on the assumption that small tumours without clinical spread have a better prognosis than larger tumours with metastases. However, it is a well-known fact that some tumours with the same clinical staging show different growth patterns and clinical behaviour. This makes the prognosis for patients with OSCC difficult to predict on the basis of clinical staging alone. Although many histopathological characteristics of OSCC have been identified as prognostic factors, none is believed to be completely infallible. Therefore, a great need exists for more reliable prognostic markers, which will assist in treatment decisions. It is now well documented that several molecular events of significance for tumour spread, such as gain and loss of adhesion molecules, secretion of proteolytic enzymes, increased cell proliferation and initiation of angiogenesis occur at the tumour–host interface or invasive front, where the deepest and presumably most aggressive cells reside. This review describes the various molecular events and interactions, which take place in the invasive front of the OSCC, and elucidates their role as prognostic markers.

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.

Central giant cell granuloma of the jaws and giant cell tumor of long bones: an immunohistochemical comparative study

OBJECTIVE

This study investigated whether some components of the extracellular matrix and CD68 expression may drive the differences between the central giant cell granuloma (CGCG) of the jaws and giant cell tumor (GCT) of long bones, which present distinct evolution and clinical behavior.

MATERIAL AND METHODS

Eight cases of CGCG and 7 cases of GCT were selected and immunohistochemically analyzed to verify the pattern of expression of CD68, tenascin (Tn) and fibronectin (Fn).

RESULTS

A large number of the mononuclear cells and multinucleated giant cells CD68+ was observed in both of the studied lesions, indicating histiocyte/ macrophage origin. Seven cases of CGCG of the jaws showed intense staining of Fn, with uniform distribution predominantly. In all 7 cases of GCT of long bones the Fn displayed intense expression, with distribution pattern varying from uniform to reticulate/fibrillar. Six cases of CGCG were intensively stained by Tn, presenting focal expression in half of specimens, and reticulate/ fibrillar pattern of expression in 4 cases. All cases of GCT of the long bones presented intense expression of Tn, uniform distribution, and reticulate/fibrillar pattern of expression in four cases.

CONCLUSIONS

The immunoexpression of CD68 in mononuclear cells and multinucleated giant cells and staining patterns of Fn and Tn were similar in both entities. These findings indicate that these proteins could not be used to explain the differences between the CGCG of the jaws and GCT of the long bones.

A quantitative co-localization analysis of large unspliced tenascin-C(L) and laminin-5/gamma2-chain in basement membranes of oral squamous cell carcinoma by confocal laser scanning microscopy

BACKGROUND

A structural interaction of the oncofetal large tenascin-C splice variants (Tn-C(L)) and the gamma2-chain of laminin-5 (Ln-5/gamma2) was recently demonstrated in oral squamous cell carcinoma (OSCC). In situ different patterns of co-localization and co-deposition of both proteins could be detected. Especially the co-localization in re-established basement membrane (BM) structures seemed to be biologically meaningful within the process of tumour progression.

METHODS

The amount of Tn-C(L) incorporated in reorganized OSCC BM structures at the tumour margins was investigated by a laser scanning microscopy-based quantitative co-localization analysis.

RESULTS

In the BM of normal oral mucosa no Tn-C(L) could be detected. In dysplastic and neoplastic oral mucosa a distinct co-localization of Tn-C(L) and Ln-5/gamma2 in the BM region could be observed. The extent of Tn-C(L) arrangement into reorganized BM structures correlated with malignancy grade.

CONCLUSIONS

The results suggest at first, a modulation of carcinomatous BM structures by the inclusion of oncofetal matrix proteins during tumour progression and secondly, the BM incorporation of the adhesion-modulating molecule Tn-C(L) as a pre-invasive structural phenomenon in OSCC.

[Oral cytology: historical development, current status, and perspectives]

Oral cytology has aroused new interest caused by introduction of the cytobrush as a sampling device and the use of additional analytical methods. By brushing it is possible to reach deeper layers of the oral mucosa where squamous intraepithelial neoplasia (SIN) begins. The biological potential of the oral epithelial cells obtained can be evaluated by the following additional methods: computer-assisted image analysis (OralCDx), DNA cytometry, immunohistochemistry, monolayer cytology, and molecular biological analysis. All of those methods can increase sensitivity (up to 100%) and specificity (up to 100%) of oral brush biopsy. Nevertheless, there are reports that oral epithelial carcinomas were not identified. No comparative study exists allowing conclusions to be drawn about the value of the single methods. Immunocytochemistry with commercial antibodies against laminin-5 is generally available and methodologically easy. Oral brush biopsy as a non invasive diagnostic method can be useful for the early detection of oral mucosal lesions. Positive findings or progression of the lesion despite negative findings are indications to refer the patient to a specialized clinic where a surgical biopsy should be performed, followed by histopathological analysis. Histopathology remains the gold standard for the definitive diagnosis of oral malignant lesions.

High-molecular tenascin-C as an indicator of atypical cells in oral brush biopsies

Tumour-invasion like wound healing is characterised by the formation of an extracellular matrix with a high tenascin-C content. The tenascin-C molecule undergoes alternative splicing. Analysis using antibody BC2 indicates that especially the high-molecular tenascin-C (hm tn-C) variants are typically tumour-associated, while distribution in normal tissue is restrictive. This study investigated whether hm tn-C is a suitable indicator of atypical cells with invasive potential in oral brush biopsies. One hundred fifty nine consecutive oral brush biopsies with histopathological diagnoses were analysed for the identification of atypical cells. A standardised haematoxylin and eosin staining plus standardised immunocytochemistry using the monoclonal anti-hm tn-C antibody was performed. The bound hm tn-C antibodies were detected with the streptavidine/alkaline phosphatase technique in the autostainer. Conventional cytology produced four false-positives when identifying atypical cells in brush biopsies of inflammatory/benign hyperproliferative mucosa (specificity 96%), while 10 in 52 carcinomas and three of eight recurrences were not identified (sensitivity 78%). Ten of these 13 non-identified tumours could be marked when adding the hm tn-C assay (increasing specificity to 99%). Combining the two assays also reduced the false-positive outcomes from four to one (increasing sensitivity to 95%). The positive and negative predictive values were 92 and 88% for conventional cytology vs 98 and 97% for the dual assay. (1) A 95%-sensitivity proves hm tn-C assisted conventional cytology to be a suitable means of identifying atypical cells in oral brush biopsies. (2) The positive (98%) and negative (97%) predictive values obtained approximate hm tn-C assisted conventional cytology to laminin-5 (100/97%).

Complex formation of the laminin-5 γ2 chain and large unspliced tenascin-C in oral squamous cell carcinoma in vitro and in situ: implications for sequential modulation of extracellular matrix in the invasive tumor front

Invasion and metastasis in oral squamous cell carcinoma (OSCC) are associated with changes in the extracellular matrix (ECM). We have previously shown an extracellular co-deposition of laminin-5 (Ln-5) and large unspliced tenascin-C (Tn-C(L)) in OSCC. Using a co-culture model of hTERT-BJ1 fibroblasts and the OSCC cell line PE/CA-PJ15, we demonstrate in the present study that Ln-5 and Tn-C(L) are not only co-deposited, but also form a physical complex which can be recovered by co-immunoprecipitation. In agreement with these results, examination of OSCC tissue specimens of different malignancy grade by means of confocal laser scanning microscopy revealed different patterns of Ln-5 and Tn-C(L) co-localization implicating complex formation also in vivo. A ribbon like co-localization was detected in subepithelial basement membranes around well differentiated OSCC parts and tumor clusters. Furthermore, a fibrillar Ln-5 gamma2 chain/Tn-C(L) co-localization occurred in the carcinoma stroma beneath tumor clusters. Additionally, at the site of ruptured basement membranes there were dot or strand like co-deposits of both molecules, but co-localizations were only rarely detectable. These different patterns may reflect a sequential modulation and reorganization of the ECM in the tumor/stroma interface as it occurs in different stages of OSCC invasion.

Proliferation and invasion factors in HIV-associated dysplastic and nondysplastic oral warts and in oral squamous cell carcinoma: an immunohistochemical and RT-PCR evaluation

OBJECTIVE

Oral warts arising in human immunodeficiency virus (HIV) infection occasionally show marked epithelial dysplasia. However, anecdotal evidence suggests that they do not progress to oral squamous cell carcinoma (SCC). Therefore, we evaluated lesions for expression of proteins (tenascin-C, beta6 integrin, and matrix metalloproteinase-1[MMP1]) that have been identified as important in the invasive phase of oral SCC.

STUDY DESIGN

Twenty-two oral dysplastic warts from 22 patients and 5 oral SCCs were stained for human papillomavirus (HPV) antigen, proliferation protein Ki-67, tenascin-C, beta6, and MMP1 by immunohistochemical methods. For comparison, 5 nondysplastic warts each from HIV-positive and HIV-negative patients and 5 normal mucosa specimens were included. Sections were semiquantitatively assessed, and results were compared. Because MMP1 was the lowest or least expressed interface protein, MMP1 mRNA was quantitatively assessed from formalin-fixed paraffin-embedded tissue in selected cases with quantitative reverse transcription-polymerase chain reaction.

RESULTS

Twenty of 22 dysplastic warts stained positive for human papillomavirus common antigen, and all warts showed high proliferative fractions similar to SCCs. Tenascin-C and beta6 were variably expressed by the dysplastic warts but were consistently expressed at high levels in the SCCs. MMP1 protein levels were negative or low in 20 of 22 in dysplastic warts, but were elevated in 4 of 5 SCCs. MMP1 mRNA analysis indicated that message was low in 4 dysplastic warts and also suggested that protein translation was incomplete in 3 of the warts.

CONCLUSION

We conclude that invasion-associated proteins are underexpressed in oral dysplastic warts in HIV-positive men. However, until these patients are followed for extended periods, the risk of development of SCC from oral dysplastic warts remains unknown.

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.

Immunohistochemical study of chondroitin-6-sulphate and tenascin in the larynx: a loss of chondroitin-6-sulphate expression accompanies squamous cell carcinoma invasion

Chondroitin 6-sulphate is a glycosaminoglycan component of both cell membrane and basement membrane proteoglycans. In vitro it can inhibit tenascin, a molecule critical for epithelial cell migration during development and in wound healing. The immunohistochemical expression of chondroitin-6-sulphate and tenascin has been examined in 143 laryngeal biopsies from 38 patients, with particular attention to changes occurring with squamous cell carcinoma invasion. All tissues were formalin-fixed and paraffin-embedded. An avidin-biotin complex immunoperoxidase technique was used. Immunostaining for chondroitin-6-sulphate was seen in the basement membrane and/or cell membranes of basal and suprabasal cells of the laryngeal epithelium. Immunostaining of cell or basement membrane was seen at least focally in 67 of 71 (94 per cent) biopsies with no atypia, in 39 of 45 (87 per cent) biopsies with mild/moderate atypia, and in 16 of 16 (100 per cent) biopsies with severe dysplasia or carcinoma in situ (CIS); but in only 2 of 18 biopsies with invasion, although in neither of these was chondroitin-6-sulphate immunostaining seen at the actual site of invasion. Tenascin immunostaining was seen along the basement membrane in all biopsies. Those with CIS or invasion showed, in addition, strong tenascin staining of the adjacent stroma. The loss of chondroitin-6-sulphate immunostaining concurrent with squamous cell carcinoma invasion in the larynx suggests that loss of a chondroitin-6-sulphate-containing proteoglycan, or a change in proteoglycan side-chain composition, is a critical step in laryngeal epithelial tumour invasion.

Synthesis and protein distribution of the unspliced large tenascin-C isoform in oral squamous cell carcinoma

The inclusion or omission of the alternatively spliced region in the tenascin-C (Tn-C) mRNA gives rise to the large (Tn-C(L)) or small (Tn-C(S)) variant, respectively. Tn-C(L) is thought to be a typical component of provisional extracellular matrices (ECMs) and is expressed during tumour stroma remodelling. Tn-C(L) synthesis has been studied using RNA/RNA in situ hybridization, and Tn-C(L) protein distribution, using immunohistochemistry (clone BC-2), in 18 oral squamous cell carcinomas (OSCCs) of different grades of malignancy. While the Tn-C(L) protein was demonstrated within the whole stromal compartment regardless of grade of malignancy, the majority of the Tn-C(L) mRNA signal-bearing cells were carcinoma cells. Only a few stromal myofibroblasts were able to synthesize Tn-C(L), as revealed by alpha-smooth muscle actin double staining. In well-differentiated carcinomas (G1), the Tn-C(L) synthesizing carcinoma cells were localized as a single positive cell layer in the tumour stroma interface, particularly in invasive areas. A higher grade of malignancy (G2/G3) is associated with a significantly increased number of Tn-C(L) synthesizing carcinoma cells randomly distributed within the invading tumour areas. Double-staining experiments (Tn-C(L) mRNA ISH/BC-2 immunohistochemistry) indicate that these cells are capable of organizing and depositing a three-dimensional Tn-C(L) matrix. Even though an instructive and/or inductive role of the carcinoma cells in tumour stroma formation cannot be excluded, these results demonstrate that carcinoma cells can directly produce the ECM components of tumour stroma.

Expression of integrin alpha9 subunit and tenascin in oral leukoplakia, lichen planus, and squamous cell carcinoma

OBJECTIVES

Integrin alpha9 subunit is a member of beta1 integrin family and binds tenascin (TN). It is expressed by stratified squamous epithelium and may be associated with cell differentiation and growth. We studied if the expression of alpha9 integrin and TN is altered in leukoplakia, lichen planus, and squamous cell carcinoma (SCC).

METHODS

Frozen sections of tissue samples obtained from normal human keratinized (16 subjects) and non-keratinized (three subjects) oral mucosa, oral leukopakias with dysplasia (19 subjects), reticular type lichen planus (nine subjects), or oral mucosal SCC (23 subjects) were stained immunohistochemically with antibodies against alpha9 integrin and TN.

RESULTS

In contrast to its most prominent localization at the cell membranes of the basal epithelial cells in the normal mucosa, alpha9 integrin was localized in a more diffuse pattern with focal loss of expression at the epithelial cell membranes in leukoplakic dysplasia, lichen planus, and SCC. In some areas of SCC, alpha9 integrin localized throughout all cell layers of the tumor epithelium. In most areas, alpha9 integrin colocalized with TN but in heavily inflamed areas there was focal loss of TN and alpha9 integrin at the basement membrane zone.

CONCLUSIONS

The findings show that alpha9 integrin expression is altered in leukoplakic dysplasia, lichen planus, and SCC.

Expression of tenascin-C in intraductal carcinoma of human breast: relationship to invasion

Tenascin-C (Tn-C) is an extracellular matrix glycoprotein that appears in areas of epithelial-mesenchymal interaction during fetal development and in neoplasia. The immunohistochemical expression of Tn-C and its relationship to histology, nuclear grade, microinvasion, oestrogen (ER) and progesterone receptors (PR), and to cell proliferation measured by Ki-67 expression were studied in 89 intraductal breast carcinomas (DCIS). Periductal Tn-C was noted in 87% and stromal Tn-C in 25% of the tumours. Stromal expression was associated with moderate to strong periductal expression and microinvasion. Periductal expression was associated with comedo-type, nuclear grade, microinvasion, Ki-67 expression, and lack of PR. The distribution of Tn-C was compared in DCIS and in the intraductal component from another series of small axillary node-negative invasive breast carcinomas (n = 44). Tn-C was present in the stroma of pure DCIS in 25% and in the intraductal component of the other series in 82%. Thus, stromal or moderate to strong periductal Tn-C expression in DCIS may relate to early invasion. DCIS with weak periductal or missing Tn-C expression may be a subgroup with benign behaviour.

Effect of snuff and smoking on tenascin expression in oral mucosa

We have shown, by using two monoclonal antibodies (143DB7 and 100EB2), that the expression of the extracellular matrix protein tenascin (Tn) is increased in the connective tissue of biopsies taken from snuff users' and tobacco smokers' oral mucosa. In normal oral mucosa Tn was seen to underlie the epithelium as a thin delicate band. The most increase in Tn reaction was observed in snuff users' mucosa while the immunoreaction in smokers' mucosa was less conspicuous. Often the most prominent Tn reaction took place in association with round cell inflammatory infiltration, indicating epithelial irritation. Tn has been shown to take part in epithelial-mesenchymal interactions during embryogenesis, wound healing and tumorigenesis. Here, a superficial epithelial irritant has been shown to cause conspicuous alterations not only in the epithelial cell layers but also in the underlying connective tissue by increasing its Tn content. As a result of our findings we suggest a further link for Tn in a dynamic epithelial-mesenchymal interplay by virtue of this marked connective tissue reaction in snuff users' and smokers' oral mucosa.

Stromal fibroblasts influence oral squamous-cell carcinoma cell interactions with tenascin-C

In this study we identified tenascin-C (TN-C) and one of its integrin receptors, alpha(v)beta6, in oral squamous-cell carcinoma (SCC) specimens. Neither TN-C nor alpha(v)beta6 are expressed in normal oral mucosa. We also studied 2 human oral squamous-cell carcinoma cell lines: the highly invasive HSC-3 cells, and the poorly invasive SCC-25 cells. We determined that adhesion of these cells to TN-C involves both alpha2 and alpha(v) integrins. Migration on TN-C by oral SCC cells required fibroblast-conditioned medium and did not occur in its absence. This migration was blocked by anti-alpha2 and anti-alpha(v) antibodies and was partially inhibited by antibodies to hepatocyte growth factor, epidermal growth factor and transforming growth factor-beta1. When seeded on TN-C, the poorly invasive SCC-25 cells formed alpha(v)beta6-positive focal contacts; the HSC-3 cells did not. HSC-3, SCC-25 and PTF cells secrete TN-C into the culture medium, as determined by Western blot. However, when HSC-3 cells were inoculated into the floor of the mouth of nude mice, only murine TN-C could be identified in the reactive stroma adjacent to the resulting tumor nests, demonstrating that in vivo, HSC-3 cells do not secrete TN-C. Our results demonstrate that alpha(v)beta6 and tenascin-C are neo-expressed in oral squamous-cell carcinoma, and that the tumor stromal environment is influential in oral SCC behavior.

Tenascin expression in mucocutaneous diseases and related lesions of human oral mucosa

The expression of tenascin was assessed immunohistochemically. In normal oral mucosa, immunoreactivity for tenascin was seen either as a delicate line underlining the epithelium or in the stromal papillae. In oral lichen planus, a marked enhancement of tenascin immunoreactivity in the lamina propria was associated with focal infiltrates of inflammatory cells and seemed to reflect the intensity of inflammation. In lichenoid reactions in which only a sparse inflammatory infiltrate was present a band-like tenascin reactivity was seen. Oral psoriform reactions and chronic hyperplastic candidosis showed a prominent tenascin reaction in the connective tissue papillae among infiltrates of inflammatory cells. The results show that tenascin content is increased in oral mucocutaneous diseases and related lesions and that the abundance of tenascin reflects the intensity of the inflammatory reaction.