Oral cancer stem cells drive tumourigenesis through activation of stromal fibroblasts.

Background: Cancer stem cells are responsible for tumour progression and chemoresistance. Fibroblasts surrounding a tumour also promote progression and fibroblast "activation" is an independent prognostic marker in oral cancer. Cancer stem cells may therefore promote tumourigenesis through communication with stromal fibroblasts.

The chemokine lymphotactin and its recombinant variants in oral cancer cell regulation.

Background: The expression of XCR1 receptor and its metamorphic ligand lymphotactin (hLtn) has been shown in cancers but their precise role in tumorigenesis is poorly understood including the significance of the physiologically existing hLtn monomeric (CC3) and dimeric (W55D) confirmations where the latter thought to function as the receptor antagonist. The aim of this study was to explore the functional role of bioengineered hLtn variants and the role of fibroblasts in XCR1/hLtn expression regulation in oral cancer cells (OCCL).

Material And Methods: qRT-PCR and flow cytometry were performed to evaluate mRNA and protein expression of XCR1 and hLtn.

Identification of key determinants in Porphyromonas gingivalis host-cell invasion assays.

The periodontal pathogen Porphyromonas gingivalis can invade host cells, a virulence trait which may contribute to the persistence of infection at subgingival sites. Whilst the antibiotic protection assay has been commonly employed to investigate and quantify P. gingivalis invasion, data obtained have varied widely and a thorough investigation of the factors influencing this is lacking.

Development and Characterization of In Vitro Human Oral Mucosal Equivalents Derived from Immortalized Oral Keratinocytes.

Tissue-engineered oral mucosal equivalents (OME) are being increasingly used to measure toxicity, drug delivery, and to model oral diseases. Current OME mainly comprise normal oral keratinocytes (NOK) cultured on top of a normal oral fibroblasts-containing matrix. However, the commercial supply of NOK is limited, restricting widespread use of these mucosal models.

Physiological Fluid Flow Moderates Fibroblast Responses to TGF-β1.

Fibroblasts are the major cellular component of connective tissue and experience mechanical perturbations due to matrix remodelling and interstitial fluid movement. Transforming growth factor β1 (TGF-β1) can promote differentiation of fibroblasts in vitro to a contractile myofibroblastic phenotype characterised by the presence of α-smooth muscle actin (α-SMA) rich stress fibres. To study the role of mechanical stimulation in this process, we examined the response of primary human fibroblasts to physiological levels of fluid movement and its influence on fibroblast differentiation and responses to TGF-β1.

The Periodontal Pathogen Porphyromonas gingivalis Preferentially Interacts with Oral Epithelial Cells in S Phase of the Cell Cycle.

Porphyromonas gingivalis, a key periodontal pathogen, is capable of invading a variety of cells, including oral keratinocytes, by exploiting host cell receptors, including alpha-5 beta-1 (α5β1) integrin. Previous studies have shown that P. gingivalis accelerates the cell cycle and prevents apoptosis of host cells, but it is not known whether the cell cycle phases influence bacterium-cell interactions.

The chemokine receptors CXCR1 and CXCR2 regulate oral cancer cell behaviour.

Background: Chemokines regulate physiological and pathological leucocyte trafficking, and chemokine receptors play a role in tumorigenesis. Expression of interleukin-8 (IL-8) receptors CXCR1 and CXCR2 has been shown in oral squamous cell carcinoma (OSCC) but remains poorly characterised. This aim of this study was to investigate CXCR1 and CXCR2 expression on normal oral keratinocytes (NOKs) and oral cancer cell lines (OCCL) and their relative response when exposed to IL-8 and growth-related oncogene-α (which selectively binds CXCR2).

Characterisation and optimisation of organotypic oral mucosal models to study Porphyromonas gingivalis invasion.

Porphyromonas gingivalis is a Gram-negative, keystone pathogen in periodontitis that leads to tissue destruction and ultimately tooth loss. The organism is able to infect oral epithelial cells and two-dimensional (monolayer) cultures have been used to investigate this process. However, recently there has been interest in the use of three-dimensional, organotypic mucosal models to analyse infection.

Temporal mismatch between pain behaviour, skin Nerve Growth factor and intra-epidermal nerve fibre density in trigeminal neuropathic pain.

Background: The neurotrophin Nerve Growth factor (NGF) is known to influence the phenotype of mature nociceptors, for example by altering synthesis of neuropeptides, and changes in NGF levels have been implicated in the pathophysiology of chronic pain conditions such as neuropathic pain. We have tested the hypothesis that after partial nerve injury, NGF accumulates within the skin and causes 'pro-nociceptive' phenotypic changes in the remaining population of sensory nerve fibres, which could underpin the development of neuropathic pain.

Results: Eleven days after chronic constriction injury of the rat mental nerve the intra-epidermal nerve fibre density of the chin skin from had reduced from 11.

ADAM 10 is over expressed in oral squamous cell carcinoma and contributes to invasive behaviour through a functional association with αvβ6 integrin.

A disintegrin and metalloprotease (ADAM) proteins are upregulated in cancer and can interact with integrin receptors. We investigated whether such interactions may have functional significance in oral squamous cell carcinoma (OSCC). ADAM 10 expression was increased in OSCC tissue and cell lines compared to normal oral mucosa.

Differential adhesion and invasion by Staphylococcus aureus of epithelial cells derived from different anatomical sites.

Staphylococcus aureus can invade epithelial cells, and the host-cell receptor α(5)β(1) integrin is thought to mediate this process. The aim of this study was to investigate S. aureus invasion of epithelial cell lines derived from oral (H357), skin (UP) and nasopharyngeal (Detroit 562) sites and to determine whether any differences were due to the levels of α(5)β(1) integrin expressed.

The role of α9β1 integrin in modulating epithelial cell behaviour.

Background: Integrins initiate signalling in response to the extracellular matrix (ECM), which is important in wound healing and cancer. Previous studies have shown that over-expression of the αvβ6 integrin in oral squamous cell carcinoma (OSCC) cells results in enhanced motility and expression of matrix-degrading proteases, and the aim of this study was to investigate whether this is also the case for the α9β1 integrin.

Methods: H357 OSCCcells were transfected with the α9 integrin subunit and proliferation, adhesion and migration assays were performed on these along with null vector control and wild-type cells.

Endothelin-1 stimulates motility of head and neck squamous carcinoma cells by promoting stromal-epithelial interactions.

The invasion and migration of cancer cells is increasingly recognised to be influenced by factors derived from adjacent tumour-associated stroma. The contextual signals regulating stromal-tumour interactions, however, remain poorly understood. Here, we identify a role for endothelin-1 (ET-1), a mitogenic peptide elevated in a number of malignancies, in promoting pro-metastatic cross-talk between head and neck cancer cells and adjacent fibroblasts.

MicroRNA-124 suppresses oral squamous cell carcinoma motility by targeting ITGB1.

Alterations in the levels of molecules which interact with the extracellular matrix, such as integrins, are associated with invasion of oral squamous cell carcinomas (OSCC). The molecular mechanisms underlying dysregulation of integrin expression in OSCC, however, remain unclear. Here, we show that microRNA-124, a small non-coding RNA down-regulated in OSCC, is able to downregulate expression of integrin beta-1 (ITGB1) by interacting with its 3' untranslated region.

The αE(CD103)β7 integrin interacts with oral and skin keratinocytes in an E-cadherin-independent manner*.

The integrin αE(CD103)β7 (αEβ7) is expressed by intraepithelial lymphocytes, dendritic cells and regulatory T cells. It plays an important role in the mucosal immune system by retaining lymphocytes within the epithelium and is involved in graft rejection, immunity against tumours and the generation of gut-homing effector cells. In gut and breast, the ligand for αEβ7 is E-cadherin but in human oral mucosa and skin, there is evidence that lymphocytes use an alternative, unknown, ligand.

Functional expression of the chemokine receptor XCR1 on oral epithelial cells.

Chemokines are chemoattractant cytokines which act on specific receptors and play an important role in leukocyte migration as well as physiological and pathological processes. We investigated the role of the chemokine receptor XCR1 and its ligand lymphotactin (Lptn/XCL1) in the regulation of oral epithelial cell behaviour. In vitro XCR1 mRNA and cell surface protein expression was detected in normal oral keratinocytes and oral squamous cell carcinoma cell lines.

Force generation and protease gene expression in organotypic co-cultures of fibroblasts and keratinocytes.

Fibroblast-epithelium interactions are crucial for successful tissue engineering of skin and oral mucosal equivalents. In this study, we assessed early force generation in organotypic fibroblast-epithelium co-cultures, using normal human keratinocytes (NHK) and HPV16-transformed (UP) cells. During the initial 2 h period, organotypic co-cultures containing both epithelial cell types produced significantly more force than fibroblasts alone (p < 0.

The 120 kDa cell-binding fragment of fibronectin up-regulates migration of alphavbeta6-expressing cells by increasing matrix metalloproteinase-2 and -9 secretion.

Changes in the extracellular matrix, integrin expression, and protease secretion occur in wound healing and cancer and these systems are thought to play a crucial role in such processes. In this study, experiments were performed to examine the interaction of epithelial cells with the 120 kDa cell-binding fibronectin fragment. Cell migration was significantly increased in response to the 120 kDa fragment when compared with the full-length molecule, but only in cells overexpressing the beta-6 integrin (VB6).

A recombinant fragment of the fibronectin-binding protein of Staphylococcus aureus inhibits keratinocyte migration.

Staphylococcus aureus is a common wound-infecting organism which can interact with cells via the extracellular matrix protein fibronectin (FN). The aim of this study was to determine the effect of the FN-binding protein (FnBP) of S. aureus on the behaviour of a human skin keratinocytes cell line (UP).

Internalization of Staphylococcus aureus by human keratinocytes.

Staphylococcus aureus is among the most important human pathogens and causes various superficial and systemic infections. The ability of S. aureus to be internalized by, and survive within, host cells, such as keratinocytes, may contribute to the development of persistent or chronic infections and may finally lead to deeper tissue infections or dissemination.

Modulation of the urokinase-type plasminogen activator receptor by the beta6 integrin subunit.

Over-expression of components of the urokinase system is well documented in cancer and is thought to enable tumour cells to migrate and invade. Changes in integrin expression are also a common feature of tumours and have been linked to changes in protease activity. It has been shown that the alphavbeta6 integrin is neo-expressed in a number of epithelial carcinomas and in wound healing situations.

Functional regulation of tissue plasminogen activator on the surface of vascular smooth muscle cells by the type-II transmembrane protein p63 (CKAP4).

We have demonstrated that tissue plasminogen activator (tPA) binds specifically to human vascular smooth muscle cells (VSMC) in a functionally relevant manner, both increasing plasminogen activation and decreasing tPA inhibition (Ellis, V., and Whawell, S. A.

Scatter factor regulation of integrin expression and function on oral epithelial cells.

Integrin receptors and the growth factor, scatter factor (SF; also known as hepatocyte growth factor) have been shown to modulate similar cellular processes including embryogenesis, wound healing and tumour invasion. The purpose of this study was to examine the role of SF in the regulation of integrin expression, migration and adhesion in normal human oral keratinocytes (NHK). Integrin expression was examined using flow cytometry, SF did not alter levels of expression but had a dramatic effect on cell morphology, inducing migratory filopodia and lamellipodia.