Loss of basement membranes in the invading front of O-1N, hamster squamous cell carcinoma with high potential of lymph node metastasis: an immunohistochemical study for laminin and type IV collagen

Revisiting laminin and extracellular matrix remodeling in metastatic squamous cell carcinoma: What have we learned after more than four decades of research?

Patients with squamous cell carcinoma (SCC) have significantly lower survival upon the development of distant metastases. The extracellular matrix (ECM) is a consistent yet dynamic influence on the metastatic capacity of SCCs. The ECM encompasses a milieu of structural proteins, signaling molecules, and enzymes. Just over 40 years ago, the fibrous ECM glycoprotein laminin was identified. Roughly four decades of research have revealed a pivotal role of laminins in metastasis. However, trends in ECM alterations in some cancers have been applied broadly to all metastatic diseases, despite evidence that these characteristics vary by tumor type. We will summarize how laminins influence the SCC metastatic process exclusively. Enhanced laminin protein deposition occurs at the invasive edge of SCC tumors, which correlates with elevated levels of laminin-binding β1 integrins on SCC cells, increased MMP-3 presence, worse prognosis, and lymphatic dissemination. Although these findings are significant, gaps in knowledge of the formation of a premetastatic niche, the processes of intra- and extravasation, and the contributions of the ECM to SCC metastatic cell dormancy persist. Bridging these gaps requires novel in vitro systems and animal models that reproduce tumor-stromal interactions and spontaneous metastasis seen in the clinic. These advances will allow accurate assessment of laminins to predict responders to transforming growth factor-β inhibitors and immunotherapy, as well as potential combinatorial therapies with the standard of care. Such clinical interventions may drastically improve quality of life and patient survival by explicitly targeting SCC metastasis.

Laminins and cancer stem cells: Partners in crime?

As one of the predominant protein families within the extracellular matrix both structurally and functionally, laminins have been shown to be heavily involved in tumor progression and drug resistance. Laminins participate in key cellular events for tumor angiogenesis, cell invasion and metastasis development, including the regulation of epithelial-mesenchymal transition and basement membrane remodeling, which are tightly associated with the phenotypic characteristics of stem-like cells, particularly in the context of cancer. In addition, a great deal of studies and reports has highlighted the critical roles of laminins in modulating stem cell phenotype and differentiation, as part of the stem cell niche. Stemming from these discoveries a growing body of literature suggests that laminins may act as regulators of cancer stem cells, a tumor cell subpopulation that plays an instrumental role in long-term cancer maintenance, metastasis development and therapeutic resistance. The accumulating evidence in this emerging research area suggests that laminins represent potential therapeutic targets for anti-cancer treatments against cancer stem cells, and that they may be used as predictive and prognostic markers to inform clinical management and improve patient survival.

Parenchymal-stromal switching for extracellular matrix production on invasion of oral squamous cell carcinoma

It is poorly understood which cell type, tumor cells, or stromal cells are responsible for the production of extracellular matrix molecules in the neoplastic stroma. We studied the expression of 4 extracellular matrix molecules at the protein and messenger RNA levels in monocellular and 2 kinds of coculture systems between human squamous cell carcinoma (ZK-1) and fibroblast (OF-1) cell lines, which may correspond to carcinoma in situ and squamous cell carcinoma, respectively. Squamous cell carcinoma and carcinoma in situ tissue sections were also investigated by immunohistochemistry and in situ hybridization for extracellular matrix. Immunohistochemically, perlecan and tenascin C were localized in carcinoma cells in carcinoma in situ, whereas they were in the stromal space in squamous cell carcinoma. In monocellular culture conditions, expression levels for perlecan, tenascin C, and laminin were more predominant in ZK-1 than in OF-1, although those for fibronectin were more enhanced in OF-1. However, these extracellular matrix expression levels of OF-1 were elevated, whereas those of ZK-1 dropped when they were in coculture conditions. The differences between ZK-1 and OF-1 were significantly more evident in direct contact (ZK-1/OF-1, 56%-22%) than in indirect contact (63%-39%). These results indicate that oral squamous cell carcinoma cells produce extracellular matrix in the absence of stromal fibroblasts (or in carcinoma in situ) and that they stop producing extracellular matrix in the presence of fibroblasts (or in squamous cell carcinoma). It is hence suggested that stromal fibroblasts after direct contact with invading squamous cell carcinoma cells are more responsible than squamous cell carcinoma cells for the formation of neoplastic stroma, whereas carcinoma in situ cells have to produce and deposit extracellular matrix by themselves to form intraepithelial microstromal spaces.

Differential expression profiles between α-dystroglycan and integrin β1 in ameloblastoma: two possible perlecan signalling pathways for cellular growth and differentiation

AIMS

Intercellular deposition of perlecan, an extracellular matrix molecule, results in characteristic stellate reticulum-like structures in ameloblastomas. The aims of this study were to elucidate which types of perlecan receptors function within any particular type of tissue architecture of ameloblastoma.

METHODS AND RESULTS

Protein and gene expression profiles for α-dystroglycan and integrin β1 were examined comparatively with those of their ligands in ameloblastoma using surgical specimens and cells in primary culture. In the follicular-type tumour cell foci, α-dystroglycan was localized uniformly over the stellate reticulum-like cells, while integrin β1 was restricted mainly to peripheral cells facing the stroma with the interface of the basement membrane, which was also rich in perlecan. In the plexiform-type, mRNA and protein signals for α-dystroglycan were enhanced in the periphery of tumour cell foci, especially in their invading fronts. Integrin β1 was also immunolocalized in the basal cell zone, which was considered to be the proliferation centre of ameloblastoma cells. Furthermore, biosynthesis of α-dystroglycan and integrin β1 by ameloblastoma cells was confirmed in vitro using immunofluorescence and reverse transcriptase-polymerase chain reaction.

CONCLUSIONS

Ameloblastoma cells proliferate and are differentiated by capturing perlecan differentially with α-dystroglycan and integrin β1, respectively.

Metastasis-associated genes in oral squamous cell carcinoma and salivary adenoid cystic carcinoma: a differential DNA chip analysis between metastatic and nonmetastatic cell systems

Overall modes of differential gene expressions were analyzed between human oral/salivary carcinoma cell systems with (MK-1 and ACCM) and without (ZK-1/ZK-2 and ACC2/ACC3) metastatic potential by using micro-array analysis with cancer-associated DNA chips to determine the kinds of genes associated with metastatic behaviors. MK-1 and/or ACCM showed lower levels of gene expression in extracellular matrix-related molecules, such as collagen type IV, laminin, and adhesion molecules such as cadherin 2, but higher levels of genes which control extracellular matrix degradation, such as MMP 9, as well as cell growth and cycle, such as FGF7 and cyclin D1. Among the differentially expressed genes, similar protein expression tendencies for FGF7, laminin, cyclin D1, and collagen type IV were confirmed by immunofluorescence. Metastatic potentials of oral/salivary carcinoma cells seem to have resulted from certain combinations of over-/underexpression of the genes, which were responsible for extracellular matrix metabolism and cell growth in particular.

Cancer progression is associated with increased expression of basement membrane proteins in three-dimensional in vitro models of human oral cancer

BACKGROUND

Although basement membrane was traditionally considered an inert barrier that tumour cells had to cross before invasion into the surrounding stroma, recent studies suggest that basement membrane components are not only degraded during tumour progression, but also newly synthesised at the invasive front.

OBJECTIVE

This study aimed at evaluating (1) the expression of basement membrane proteins in human oral carcinogenesis and (2) the role that epithelial-mesenchymal interactions play on it, by using an in vitro oral cancer progression model.

MATERIAL AND METHODS

In vitro three-dimensional (3D) organotypic cultures of normal, early neoplastic and neoplastic human oral mucosa were developed by growing primary normal human oral keratinocytes, dysplastic human oral keratinocytes (DOK cell line), and neoplastic human oral keratinocytes (PE/CA-PJ15 cell line) on type I collagen biomatrices, with or without primary fibroblasts isolated from normal human oral mucosa. The cultured tissues were immunohistochemically assessed for the expression of the major basement membrane proteins laminin-332, type IV collagen, and fibronectin.

RESULTS

Expression of laminin-332, type IV collagen, and fibronectin was gradually more pronounced in neoplastic models when compared to normal mucosa models, and, with the exception of laminin-332, it was further enhanced by presence of fibroblasts. Deposition of type IV collagen at the epithelium-biomatrix interface occurred only in presence of fibroblasts, as well as the extracellular matrix deposition of fibronectin.

CONCLUSIONS

These findings, obtained in a 3D in vitro model that closely mirrors the in vivo human oral cancer progression, show an enhanced basement membrane protein expression during human oral cancer progression that is dependent on the epithelial-mesenchymal environment, respectively the existence of fibroblasts.

Lymphatic involvement in the histopathogenesis of mucous retention cyst

Mucous retention cyst results from extravasation of saliva. Our intent was to study the role of lymphatics in its pathogenesis. Twenty-three surgical specimens of mucous retention cyst of the lip were examined for involvement of lymphatic vessels by a comparative immunohistochemical demonstration of lymphatic and blood vascular endothelial cells, as well as lymphatic and salivary contents. Mucous retention cysts were histopathologically classified into three stages: early, intermediate, and advanced. In the early stage, there was diffuse extravasation of mucous material in the interstitium of the lamina propria or the submucosal layer of the oral mucosa. In the intermediate stage, lymphatics, which were clearly revealed and immunohistochemically distinguished from blood vessels by monoclonal antibody D2-40, were dilated and finally ruptured, leaving fragments of lymphatic walls in the periphery of mucous pools. In the advanced stage, thick cyst walls of granulation tissue were formed around mucous retention. Lymphatics were no longer involved in the granulation tissue wall, which was actively driven by blood vessel formation. The results suggest that the lymphatic rupture seems to contribute to the enlargement in the pathogenesis of mucous retention cyst.

Extracellular matrix remodeling in oral submucous fibrosis: its stage-specific modes revealed by immunohistochemistry and in situ hybridization

BACKGROUND

Oral submucous fibrosis (OSF) is a chewing habit-related pre-cancerous condition of the oral mucosa affecting predominantly south Asians. It is histopathologically characterized by epithelial atrophy and fibrosis of the subepithelial connective tissue. Fibrosis extends all the way into the muscle layer, leading to difficulty in mouth opening. However, the dynamics of extracellular matrix (ECM) remodeling with OSF progression is largely unknown.

METHODS

Forty biopsy specimens of OSF and 10 of normal buccal mucosa were examined for expression/deposition modes of eight ECM molecules by histochemistry, immunohistochemistry, and in situ hybridization.

RESULTS

In the early stage of OSF, tenascin, perlecan, fibronectin, collagen type III were characteristically enhanced in the lamina propria and the submucosal layer. In the intermediate stage, the ECM molecules mentioned above and elastin were extensively and irregularly deposited around muscle fibers. In the advanced stage, such ECM depositions decreased and were entirely replaced with collagen type I only. Their gene expression levels varied with progression of fibrosis, but the mRNA signals were confirmed in fibroblasts in the submucosal fibrotic areas.

CONCLUSIONS

The results indicate that the ECM remodeling steps in OSF are similar to each phase of usual granulation tissue formation. Restricted mouth opening may be a result of loss of variety of ECM molecules including elastin into the homogeneity of collagen type I replacing muscle fibers.

Rationale for Sentinel Node Biopsy to Stage N0 Head and Neck Squamous-Cell Carcinoma

Sentinel node biopsy is an evolving staging tool in the management of patients with squamous-cell carcinoma of the head and neck. This tool provides a more detailed understanding of the lymphatic pathways within the head and neck and the role of these pathways regarding tumor spreading. By targeting nodes that are most likely to harbor disease, a more detailed pathological evaluation of sentinel nodes is possible-thus improving staging by the identification of micrometastases. The rationale behind the use of sentinel node biopsy to stage the N0 neck are discussed within this paper.

Vascular invasion in squamous cell carcinomas of human oral mucosa

The process of vascular invasion of human oral squamous cell carcinomas was histologically and immunohistochemically studied in surgical and autopsy specimens. Hematoxylin-eosin, Masson's trichrome, and immunohistochemical stainings for Ulex europaeus I lectin binding, CD31, and type IV collagen were done to differentiate lymphatic and blood vessels and to demonstrate basement membranes in vascular walls and around carcinoma cell nests was observed. With growth of tumor, there was mechanical disruption of vascular walls and endothelial cells by carcinoma cell nests. After disrupting vascular walls, they invaded into the lumen as clusters, not as single cells. At the blood vessel invasion sites, inflammatory reactions were seen around carcinoma cell nests inside as well as outside lumina with microthrombotic reactions due to endothelial injury. At the lymphatic invasion sites, carcinoma cell nests maintained their volume inside the lumen and the cells adhered tightly to each other, and inflammatory reaction was scarcely seen. These findings showed that mechanical pressure has an important role in the vascular invasion of human oral squamous cell carcinoma.

Distribution of laminin and fibronectin isoforms in oral mucosa and oral squamous cell carcinoma

The expression of laminin and fibronectin isoforms varies with cellular maturation and differentiation and these differences may well influence cellular processes such as adhesion and motility. The basement membrane (BM) of fetal oral squamous epithelium contains the laminin chains, alpha2, alpha3, alpha5, beta1, beta2, beta3, gamma1 and gamma2. The BM of adult normal oral squamous epithelium comprises the laminin chains, alpha3, alpha5, beta1, beta3, gamma1 and gamma2. A re-expression of the laminin alpha2 and beta2 chains could be shown in adult hyperproliferative, dysplastic and carcinomatous lesions. In dysplasia and oral squamous cell carcinoma (OSCC), multifocal breaks of the BM are present as indicated by laminin chain antibodies. These breaks correlate to malignancy grade in their extent. Moreover, in the invasion front the alpha3 and gamma2 chain of laminin-5 can immunohistochemically be found outside the BM within the cytoplasm of budding carcinoma cells and in the adjacent stroma. The correlation between the morphological pattern of invasive tumour clusters and a laminin-5 immunostaining in the adjacent stroma may suggest, first, that a laminin-5 deposition outside the BM is an immunohistochemical marker for invasion and second, that OSCC invasion is guided by the laminin-5 matrix. Expression of oncofetal fibronectins (IIICS de novo glycosylated fibronectin and ED-B fibronectin) could be demonstrated throughout the stromal compartment. However, the ED-B fibronectin synthesizing cells (RNA/RNA in situ hybridization) are confined to small stroma areas and to single stroma and inflammatory cells in the invasion front. A correlation of the number of ED-B fibronectin synthesizing cells to malignancy grade could not be seen. ED-B fibronectin mRNA-positive cells seem to be concentrated in areas of fibrous stroma recruitment with a linear alignment of stromal fibro-/myofibroblasts (desmoplasia). Double staining experiments (ED-B fibronectin in situ hybridization and alpha-smooth muscle actin immunohistochemistry) indicated that the stroma myofibroblasts are a preferential source of ED-B fibronectin. In conclusion, in OSCC, a fetal extracellular matrix conversion is demonstrable. Tumour cells (laminin alpha2 and beta2 chain) and recruited stromal myofibroblasts (oncofetal ED-B fibronectin) contribute to the fetal extracellular matrix milieu.

Pericoronal hamartomatous lesions in the opercula of teeth delayed in eruption: an immunohistochemical study of the extracellular matrix

Opercula of teeth delayed in eruption were examined histopathologically and immunohistochemically to determine the possible causes for tooth eruption failure. Specimens were obtained from 58 patients with non-erupted teeth by surgical removal of their gingival opercula. Among the 61 specimens, 31 (50.8%) were diagnosed as pericoronal myxofibrous hyperplasia (PMH), 8 (13.1%) as infantile ameloblastic fibromatosis (IAF), and 19 (31.2%) as odontomas. Histopathologically, PMH is characterized by hyperplasia of odontogenic mesenchymal tissues with a myxoid appearance in which odontogenic epithelial islands and mesenchymal multinucleated giant cells are scattered randomly. Between the mucosal epithelium and the PMH, there is a layer of fibrosis, whose matrix is strongly immunopositive for tenascin. The PMH seems to induce its overlying gingival mucosa to remodel the connective tissue, which obstructs tooth eruption. IAF is usually located adjacent to the PMH and shows an ameloblastic fibroma-like histology with atrophic ameloblastic components and poor encapsulation. The findings suggest that IAF associated with PMH is not a true neoplasm and should be distinguished from ameloblastic fibromas by the name of IAF, and that both lesions are included in the range of hamartomas formed only in the pericoronal tissue of teeth in eruption. We propose to categorize these lesions into a new disease entity of pericoronal hamartomas of odontogenic origin.