Keratinocyte migration requires alpha2beta1 integrin-mediated interaction with the laminin 5 gamma2 chain

The basement membrane in epidermal polarity, stemness, and regeneration

The epidermis is a specialized epithelium that constitutes the outermost layer of the skin, and it provides a protective barrier against environmental assaults. Primarily consisting of multilayered keratinocytes, the epidermis is continuously renewed by proliferation of stem cells and the differentiation of their progeny, which undergo terminal differentiation as they leave the basal layer and move upward toward the surface, where they die and slough off. Basal keratinocytes rest on a basement membrane at the dermal-epidermal junction that is composed of specific extracellular matrix proteins organized into interactive and mechanically supportive networks. Firm attachment of basal keratinocytes, and their dynamic regulation via focal adhesions and hemidesmosomes, is essential for maintaining major skin processes, such as self-renewal, barrier function, and resistance to physical and chemical stresses. The adhesive integrin receptors expressed by epidermal cells serve structural, signaling, and mechanosensory roles that are critical for epidermal cell anchorage and tissue homeostasis. More specifically, the basement membrane components play key roles in preserving the stem cell pool, and establishing cell polarity cues enabling asymmetric cell divisions, which result in the transition from a proliferative basal cell layer to suprabasal cells committed to terminal differentiation. Finally, through a well-regulated sequence of synthesis and remodeling, the components of the dermal-epidermal junction play an essential role in regeneration of the epidermis during skin healing. Here too, they provide biological and mechanical signals that are essential to the restoration of barrier function.

Invasion-Associated Reorganization of Laminin 332 in Oral Squamous Cell Carcinomas: The Role of the Laminin γ2 Chain in Tumor Biology, Diagnosis, and Therapy

Simple Summary

The destructive growth of carcinomas is associated with crossing the border between the epithelial and the connective tissue parts of an organ. One component of this borderline, the basement membrane, is the heterotrimeric laminin 332, which mediates the adhesion of basal epithelial cells. This protein, in particular its gamma 2 chain, is fundamentally reorganized during tumor cell invasion. Specific deposition patterns of laminin 332 are also present in oral squamous cell carcinomas and have been shown to be of high diagnostic and predictive value. Furthermore, laminin 332 restructuring is associated with important tumor biological processes, e.g., stromal activation, the development of a motile phenotype, and tumor spreading. In this review, current knowledge in the field is summarized and the recommendation to consider laminin 332 as a promising grading and monitoring parameter and as a potential therapeutic target is discussed.

Abstract

Invasion of the connective tissue by carcinoma cells is accompanied by disintegration and reorganization of the hemidesmosomes, which connect the basement membrane to the basal epithelial cells. In terms of mediating the basement membrane, i.e., basal cell interactions, the heterotrimeric laminin 332 is the most important bridging molecule. Due to this distinct function, laminin 332, especially its gamma 2 chain, came into the focus of cancer research. Specific de novo synthesis and deposition patterns of laminin 332 are evident upon development and progression of oral squamous cell carcinomas (OSCCs). Loss from the basement membrane, cytoplasmic accumulation, and extracellular deposition are associated with crucial processes such as stromal activation and immune response, epithelial to mesenchymal transition, and tumor cell budding. In networks with components of the tumor microenvironment, altered expression of laminin 332 chains, proteolytic processing, and interaction with integrin receptors seem to promote cancer cell migration. Indeed, reorganization patterns are shown to have a high diagnostic and prognostic value. Here, we summarize the current knowledge on laminin 332 reorganization in OSCCs with special focus on its gamma 2 chain and provide, based on the current literature, evidence on its promising role as a grading and monitoring parameter and as a potential therapeutic target.

Cotransplantation of Limbal Epithelial and Stromal Cells for Ocular Surface Reconstruction

Purpose

To propose an improved stem cell-based strategy for limbal stem cell deficiency (LSCD) treatment.

Design

Experimental randomized or parallel-group animal study.

Subjects

Fifty adult male New Zealand white rabbits.

Methods

Human limbal stem/progenitor cells (LSCs) and limbal stromal stem/progenitor cells (LSSCs) were cultured in serum-free conditions and further differentiated into corneal epithelial cells and keratocytes, respectively. All cell types were characterized with lineage-specific markers. Gene expression analysis was performed to identify the potential function of LSSCs in corneal regeneration. Two LSCD models of rabbits for transplantations were used: transplantation performed at the time of limbal and corneal epithelial excision (LSCD model) and transplantation performed after clinical signs were induced in an LSCD model (pLSCD model). The pLSCD model better mimics the pathologic changes and symptoms of human LSCD. Rabbit models received LSC or LSC plus LSSC treatment. Corneal epithelial defects, neovascularization, and opacity were assessed every 3 weeks for 24 weeks. ZsGreen-labeled LSSCs were used for short-term tracking in vivo.

Main Outcome Measures

Rates of corneal epithelial defect area, corneal neovascularization and opacity scores, graft survival rate, and immunofluorescence staining of specific markers.

Results

Both LSC transplantation and LSC plus LSSC cotransplantation effectively repaired the corneal surface in the LSCD model. These 2 strategies showed no significant differences in terms of graft survival rate or epithelial repair. However, corneal opacity was observed in the LSC group (in 3 of 8 rabbits), but not in the LSC plus LSSC group. Notably, when treating LSCD rabbits with distinguishable stromal opacification and neovascularization, cotransplantation of LSCs and LSSCs exhibited significantly better therapeutic effects than transplantation of LSCs alone, with graft survival rates of 87.5% and 37.5%, respectively. The implanted LSSCs could differentiate into keratocytes during the wound-healing process. RNA sequencing analysis showed that the stromal cells produced not only a collagen-rich extracellular matrix to facilitate reconstruction of the lamellar structure, but also niche factors that accelerated epithelial cell growth and inhibited angiogenesis and inflammation.

Conclusions

These findings highlight the support of stromal cells in niche homeostasis and tissue regeneration, providing LSC plus LSSC cotransplantation as a new treatment strategy for corneal blindness.

Ultrasonographic Assessment of the Cutaneous Changes Induced by Topical Use of Novel Peptides Comprising Laminin 5

Background  Laminin 5, which is found in the basement membrane of dermal-epidermal junction (DEJ), is a major adhesive component and associated with proliferating and migrating keratinocytes. In this study, we hypothesized that the topical application of the skin care products containing the novel peptides might restore the DEJ structure by deriving deposition of laminin 5 and promoting the keratinocyte migration. Here, we evaluated the restoration of DEJ by measuring the skin thickness.

Methods  Single-center retrospective analysis was performed on a total of 13 patients who underwent skin care using Baume L.C.E. (France, Laboratories d' Anjou) between January and March 2021. All patients applied the skin care agent for 2 weeks only on their left hand dorsum. Before the initiation of the application and after 2 weeks, both their hands were evaluated on photography and ultrasound. And the patients were asked to rate their satisfaction with the questionnaire after 2 weeks.

Results  There was no obvious improvement in photographic assessment and questionnaire. The post–pre difference of skin thickness in ultrasound images was, in left hand, 0.1 ± 0.37 in distal point and 0.1 ± 0.35 in proximal point; and, in right hand, 0 ± 0.17 in distal point and 0 ± 0.15 in proximal point, respectively. The pre–post difference was statistically significant in proximal point ( p  = 0.035).

Conclusion  Topical application of novel peptide derivative comprising laminin 5 demonstrated cutaneous changes including skin thickness, as assessed by ultrasound. Further studies using other modalities including dermal density measurement, three-dimensional photography, optical coherence tomography, or skin biopsy would be helpful to determine the skin-improving effects.

α2β1 integrins spatially restrict Cdc42 activity to stabilise adherens junctions

Background

Keratinocytes form the main protective barrier in the skin to separate the underlying tissue from the external environment. In order to maintain this barrier, keratinocytes form robust junctions between neighbouring cells as well as with the underlying extracellular matrix. Cell–cell adhesions are mediated primarily through cadherin receptors, whereas the integrin family of transmembrane receptors is predominantly associated with assembly of matrix adhesions. Integrins have been shown to also localise to cell–cell adhesions, but their role at these sites remains unclear.

Results

Here we show that α2β1 integrins are enriched at mature keratinocyte cell–cell adhesions, where they play a crucial role in organising cytoskeletal networks to stabilize adherens junctions. Loss of α2β1 integrin has significant functional phenotypes associated with cell–cell adhesion destabilisation, including increased proliferation, reduced migration and impaired barrier function. Mechanistically, we show that α2β1 integrins suppress activity of Src and Shp2 at cell–cell adhesions leading to enhanced Cdc42–GDI interactions and stabilisation of junctions between neighbouring epithelial cells.

Conclusion

Our data reveals a new role for α2β1 integrins in controlling integrity of epithelial cell–cell adhesions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12915-021-01054-9.

Interaction between laminin-5γ2 and integrin β1 promotes the tumor budding of colorectal cancer via the activation of Yes-associated proteins

Colorectal cancer (CRC) is a common cancer type and a threat to human health. Tumor budding (TB) is the presence of a single cancer cell or clusters of up to five cancer cells prior to the invasive front of an aggressive carcinoma and is an independent prognosis factor for CRC. The molecular mechanism of TB is still unclear, and drugs that inhibit this process are still in the blank stage. This study found that TBs exhibit characteristics of partial EMT with a decreased expression of E-cadherin and no substantial differences in the expression of N-cadherin and vimentin. We also observed the interaction of integrin with extracellular matrix components, laminin-5γ2 (LN-5γ2), play essential roles in the TB of CRC. We then verified that the interaction between LN-5γ2 and integrin β1 promotes the TB of CRC via the activation of FAK and Yes-associated proteins (YAP). A natural drug monomer, cucurbitacin B, was screened using virtual screening methods for the interaction interface of proteins. We found that this monomer could block the interaction interface between LN-5γ2 and integrin β1 and substantially inhibit the TB of CRC cells via inactivation of YAP. This study provides new insights into the mechanism of TB mechanism and the development of drugs targeting the TB of CRC.

The intercellular expression of type-XVII collagen, laminin-332, and integrin-β1 promote contact following during the collective invasion of a cancer cell population

Cancer cells can invade as a population in various cancer tissues. This phenomenon is called collective invasion, which is associated with the metastatic potential and prognosis of cancer patients. The collectiveness of cancer cells is necessary for collective invasion. However, the mechanism underlying the generation of collectiveness by cancer cells is not well known. In this study, the phenomenon of contact following, where neighboring cells move in the same direction via intercellular adhesion, was investigated. An experimental system was created to observe the two-dimensional invasion using a collagen gel overlay to study contact following in collective invasion. The role of integrin-β1, one of the major extracellular matrix (ECM) receptors, in contact following was examined through the experimental system. Integrin-β1 was localized to the intercellular site in squamous carcinoma cells. Moreover, the intercellular adhesion and contact following were suppressed by treatment of an integrin-β1 inhibitory antibody. ECM proteins such as laminin-332 and type-XVII collagen were also localized to the intercellular site and critical for contact following. Collectively, it was demonstrated that the activity of integrin-β1 and expression of ECM proteins in the intercellular site promote contact following in the collective invasion of a cancer cell population.

Laminin 332-Dependent YAP Dysregulation Depletes Epidermal Stem Cells in Junctional Epidermolysis Bullosa

Laminin 332-deficient junctional epidermolysis bullosa (JEB) is a severe genetic skin disease. JEB is marked by epidermal stem cell depletion, the origin of which is unknown. We show that dysregulation of the YAP and TAZ pathway underpins such stem cell depletion. Laminin 332-mediated YAP activity sustains human epidermal stem cells, detected as holoclones. Ablation of YAP selectively depletes holoclones, while enforced YAP blocks conversion of stem cells into progenitors and indefinitely extends the keratinocyte lifespan. YAP is dramatically decreased in JEB keratinocytes, which contain only phosphorylated, inactive YAP. In normal keratinocytes, laminin 332 and α6β4 ablation abolish YAP activity and recapitulate the JEB phenotype. In JEB keratinocytes, laminin 332-gene therapy rescues YAP activity and epidermal stem cells in vitro and in vivo. In JEB cells, enforced YAP recapitulates laminin 332-gene therapy, thus uncoupling adhesion from proliferation in epidermal stem cells. This work has important clinical implication for ex vivo gene therapy of JEB.

Microscale roughness regulates laminin-5 secretion of bone marrow mesenchymal stem cells

Laminin-5 (Ln-5), an important extracellular matrix (ECM) protein, plays a critical role in regulating the growth and differentiation of mesodermal tissues, including bone. Ln-5 can be secreted by the mesenchymal stem cells (MSCs), and Ln-5 promotes MSCs osteogenic differentiation. It has been demonstrated that a substrate's surface topography could regulate MSC secretion and differentiation. A better understanding of the mechanism of how Ln-5 and surface roughness regulate MSC osteogenic differentiation would guide the design of surface topography and coatings of orthopedic implants and cell culture substrates. However, few studies have investigated the relationship between surface roughness and the secretion of Ln-5 in MSC osteogenic differentiation. Whether substrate surface topography regulates MSC differentiation via regulating Ln-5 secretion and how surface topography contributes to the secretion of Ln-5 are still not known. In this study, the influence of microscale roughness at different levels (R0, R1 and R2) on the secretion of Ln-5 of human bone marrow MSCs (hBMSCs) and subsequent osteogenic differentiation were examined. hBMSCs spreading, distribution and morphology were greatly affected by different roughness levels. A significantly higher level of Ln-5 secretion was detected on R2, which correlated to the local cell density regulated by the rough surface. Ln-5 binding integrins (α2 and α3) were strongly activated on R2. In addition, the results from hBMSCs on R0 inserts with different cell densities further confirmed that local cell density regulated Ln-5 secretion and cell surface integrin activation. In addition, the mineralization level of MSCs on R2 was remarkably higher than that on R0 and R1. These results suggest that hBMSC osteogenic differentiation level on R2 roughness was enhanced via increased Ln-5 secretion that was attributed to rough surface regulated local cell density. Thus, the microroughness could serve as effective topographical stimulus in cell culture devices and bone implant materials.

The Interaction between Laminin-332 and α3β1 Integrin Determines Differentiation and Maintenance of CAFs, and Supports Invasion of Pancreatic Duct Adenocarcinoma Cells

Ranking among the most lethal tumour entities, pancreatic duct adenocarcinoma cells invade neighbouring tissue resulting in high incidence of metastasis. They are supported by tumour stroma fibroblasts which have undergone differentiation into cancer-associated fibroblasts (CAFs). Stiffness of cell substratum, cytokines, such as transforming growth factor-β (TGF-β), and stromal matrix proteins, such as laminin-332, are factors which promote CAF differentiation. In a spheroid culture system, differentiation of CAFs was analysed for laminin-332 production, laminin-binding integrin repertoire, adhesion and migration behaviour, and, in heterospheroids, for their interplay with the pancreatic duct adenocarcinoma AsPC-I cells. Our data reveal that CAFs produce laminin-332 thus contributing to its ectopic deposition within the tumour stroma. Moreover, CAF differentiation correlates with an increased expression of α3β1 integrin, the principal laminin-332-receptor. Beyond its role as novel CAF marker protein, integrin α3β1 crucially determines differentiation and maintenance of the CAF phenotype, as knock-out of the integrin α3 subunit reversed the CAF differentiated state. AsPC-I cells co-cultured in heterospheroids with integrin α3-deficient CAFs invaded less than from heterospheroids with wild-type CAFs. This study highlights the role of integrin α3β1 integrin-laminin-332 interaction of CAFs which promotes and sustains differentiation of CAFs and promotes carcinoma invasion.

Epidermolysis bullosa: Molecular pathology of connective tissue components in the cutaneous basement membrane zone

Epidermolysis bullosa (EB), a group of heritable skin fragility disorders, is characterized by blistering, erosions and chronic ulcers in the skin and mucous membranes. In some forms, the blistering phenotype is associated with extensive mutilating scarring and development of aggressive squamous cell carcinomas. The skin findings can be associated with extracutaneous manifestations in the ocular as well as gastrointestinal and vesico-urinary tracts. The phenotypic heterogeneity reflects the presence of mutations in as many as 20 different genes expressed in the cutaneous basement membrane zone, and the types and combinations of the mutations and their consequences at the mRNA and protein levels contribute to the spectrum of severity encountered in different subtypes of EB. This overview highlights the molecular genetics of EB based on mutations in the genes encoding type VII and XVII collagens as well as laminin-332. The mutations identified in these protein components of the extracellular matrix attest to their critical importance in providing stability to the cutaneous basement membrane zone, with implications for heritable and acquired diseases.

Proteome-wide changes in primary skin keratinocytes exposed to diesel particulate extract-A role for antioxidants in skin health

BACKGROUND

Skin acts as a protective barrier against direct contact with pollutants but inhalation and systemic exposure have indirect effect on keratinocytes. Exposure to diesel exhaust has been linked to increased oxidative stress.

OBJECTIVE

To investigate global proteomic alterations in diesel particulate extract (DPE)/its vapor exposed skin keratinocytes.

METHODS

We employed Tandem Mass Tag (TMT)-based proteomics to study effect of DPE/DPE vapor on primary skin keratinocytes.

RESULTS

We observed an increased expression of oxidative stress response protein NRF2, upon chronic exposure of primary keratinocytes to DPE/its vapor which includes volatile components such as polycyclic aromatic hydrocarbons (PAHs). Mass spectrometry-based quantitative proteomics led to identification 4490 proteins of which 201 and 374 proteins were significantly dysregulated (≥1.5 fold, p≤0.05) in each condition, respectively. Proteins involved in cellular processes such as cornification (cornifin A), wound healing (antileukoproteinase) and differentiation (suprabasin) were significantly downregulated in primary keratinocytes exposed to DPE/DPE vapor. These results were corroborated in 3D skin models chronically exposed to DPE/DPE vapor. Bioinformatics analyses indicate that DPE and its vapor affect distinct molecular processes in skin keratinocytes. Components of mitochondrial oxidative phosphorylation machinery were seen to be exclusively overexpressed upon chronic DPE vapor exposure. In addition, treatment with an antioxidant like vitamin E partially restores expression of proteins altered upon exposure to DPE/DPE vapor.

CONCLUSIONS

Our study highlights distinct adverse effects of chronic exposure to DPE/DPE vapor on skin keratinocytes and the potential role of vitamin E in alleviating adverse effects of environmental pollution.

Role of integrins in wound repair and its periodontal implications

Wound healing in human periodontium is a complex process which involves both cell-cell and cell-matrix interactions. Integrins play a major role in regulation of these cell-cell, cell-matrix interaction. Wound healing involves two major events i.e. re-epithelialization and connective tissue repair. In this concise review, we will discuss the role of integrins in these major events as well as their impIications in periodontal wound repair. Integrins are differentially expressed in both of these major events. In re-epithelialization, keratinocytes express novel integrins receptors αvβ1, α5β1and αvβ6 which are not expressed in normal healthy epithelium. Re-epithelialization also involves interaction of integrins with TGF-β and fibronectin. Similarly, in connective tissue repair, the activation of fibroblast as well as the expression of integrins α5β1 and α3β1 is upregulated. In healthy periodontium, integrin αvβ6 is normally expressed in junctional epithelium which is generally expressed only at wound sites in other parts of the body. The epithelialization at implant surface has not been yet fully explored with respect to interactions among integrins and other extra-cellular matrix molecules.

Preserving Basement Membranes during Detachment of Cultivated Oral Mucosal Epithelial Cell Sheets for the Treatment of Total Bilateral Limbal Stem Cell Deficiency

Total bilateral limbal stem cell deficiency leading to loss of corneal clarity, potential vision loss, pain, photophobia, and keratoplasty failure cannot be treated by autologous limbal transplantation, and allogeneic limbal transplantation requires subsequent immunosuppressive treatment. Cultured autologous oral mucosal epithelial cells have been shown to be safe and effective alternatives. These cells can be transplanted on supports or without support after detachment from the culture dishes. Dispase, known for epidermal sheet detachment, is reported as not usable for oral mucosa. The objective was to find an optimized detachment method providing a sufficiently resistant and adhesive cultured oral mucosal epithelium (COME), which can be grafted without sutures. Enzymatic treatments (dispase or collagenase at different concentrations) were compared to enzyme-free mechanical detachment. Histological immunofluorescence (IF) and Western blotting (WB) were used to examine the impact on adhesion markers (laminin-332, β1-integrin, and type VII collagen) and junctional markers (E-cadherin, P-cadherin). Finally, the COME ability to adhere to the cornea and produce a differentiated epithelium 15 d after grafting onto an ex vivo porcine stroma model were investigated by histology, IF, and transmission electron microscopy. Collagenase at 0.5 mg/mL and dispase at 5 mg/mL were selected for comparative study on adhesive expression marker by IF and WB showed that levels of basement membrane proteins and cell-cell and cell-matrix junction proteins were not significantly different between the 3 detachment methods. Collagenase 0.5 mg/mL was selected for the next step validation because of the better reproducibility, 100% success (vs. 33% with dispase 5 mg/mL). Grafted onto porcine de-epithelialized corneal stroma, collagenase 0.5 mg/mL detached COME were found to adhere, stratify, and continue to ensure renewal of the epithelium. For COME, collagenase 0.5 mg/mL enzymatic detachment was selected and validated on its resistance and adhesive marker expression as well as their anchorage onto our new ex vivo de-epithelialized stroma model.

Extracellular matrix contribution to skin wound re-epithelialization

The ability of skin to act as a barrier is primarily determined by cells that maintain the continuity and integrity of skin and restore it after injury. Cutaneous wound healing in adult mammals is a complex multi-step process that involves overlapping stages of blood clot formation, inflammation, re-epithelialization, granulation tissue formation, neovascularization, and remodeling. Under favorable conditions, epidermal regeneration begins within hours after injury and takes several days until the epithelial surface is intact due to reorganization of the basement membrane. Regeneration relies on numerous signaling cues and on multiple cellular processes that take place both within the epidermis and in other participating tissues. A variety of modulators are involved, including growth factors, cytokines, matrix metalloproteinases, cellular receptors, and extracellular matrix components. Here we focus on the involvement of the extracellular matrix proteins that impact epidermal regeneration during wound healing.

Smad2 overexpression enhances adhesion of gingival epithelial cells

OBJECTIVE

Gingival epithelial cells play an important role in preventing the initiation of periodontitis, by their hemidesmosomal adhesion to the tooth root surface. Adhesion requires integrin-extracellular matrix (ECM) interactions that are intricately regulated by transforming growth factor-β (TGF-β) signaling. However, the mechanisms underlying the interplay between adhesion molecules and TGF-β, especially the respective roles of Smad2 and Smad3, remain elusive. In this study, we examined the effects of Smad overexpression on gingival epithelial cell adhesion and expression profiles of integrin and ECM-related genes.

METHODS

Human gingival epithelial cells immortalized by the SV40 T-antigen were transfected with Smad2- and Smad3-overexpression vectors. A cell adhesion assay involving fluorescence detection of attached cells was performed using the ArrayScan imaging system. Real-time PCR was performed to examine the kinetics of integrin and ECM gene expression. In vitro and in vivo localization of adhesion molecules was examined by immunofluorescence analysis.

RESULTS

By using SB431542, a specific inhibitor of the TGF-β type I receptor, Smad2/3 signaling was confirmed to be dominant in TGF-β1-induced cell adhesion. The Smad2-transfectant demonstrated higher potency for cell adhesion and integrin expression (α2, α5, β4, and β6) than the Smad3-transfectant, whereas little or no change in ECM expression was observed in either transfectant. Moreover, the gingival epithelium of transgenic mice that overexpressed Smad2 driven by the keratin 14 promoter showed increased integrin α2 expression.

CONCLUSION

These findings indicate the crucial role of Smad2 in increased adhesion of gingival epithelial cells via upregulation of integrin α2.

FOXO1 differentially regulates both normal and diabetic wound healing

FOXO1 differentially regulates normal and diabetic wound healing through a switch in downstream targets influenced by the effect of glucose and advanced glycation end products.

Healing is delayed in diabetic wounds. We previously demonstrated that lineage-specific Foxo1 deletion in keratinocytes interfered with normal wound healing and keratinocyte migration. Surprisingly, the same deletion of Foxo1 in diabetic wounds had the opposite effect, significantly improving the healing response. In normal glucose media, forkhead box O1 (FOXO1) enhanced keratinocyte migration through up-regulating TGFβ1. In high glucose, FOXO1 nuclear localization was induced but FOXO1 did not bind to the TGFβ1 promoter or stimulate TGFβ1 transcription. Instead, in high glucose, FOXO1 enhanced expression of serpin peptidase inhibitor, clade B (ovalbumin), member 2 (SERPINB2), and chemokine (C-C motif) ligand 20 (CCL20). The impact of high glucose on keratinocyte migration was rescued by silencing FOXO1, by reducing SERPINB2 or CCL20, or by insulin treatment. In addition, an advanced glycation end product and tumor necrosis factor had a similar regulatory effect on FOXO1 and its downstream targets and inhibited keratinocyte migration in a FOXO1-dependent manner. Thus, FOXO1 expression can positively or negatively modulate keratinocyte migration and wound healing by its differential effect on downstream targets modulated by factors present in diabetic healing.

LAMC2 enhances the metastatic potential of lung adenocarcinoma

Lung cancer is the number one cancer killer, and metastasis is the main cause of high mortality in lung cancer patients. However, mechanisms underlying the development of lung cancer metastasis remain unknown. Using genome-wide transcriptional analysis in an experimental metastasis model, we identified laminin γ2 (LAMC2), an epithelial basement membrane protein, to be significantly upregulated in lung adenocarcinoma metastatic cells. Elevated LAMC2 increased traction force, migration, and invasion of lung adenocarcinoma cells accompanied by the induction of epithelial-mesenchymal transition (EMT). LAMC2 knockdown decreased traction force, migration, and invasion accompanied by EMT reduction in vitro, and attenuated metastasis in mice. LAMC2 promoted migration and invasion via EMT that was integrin β1- and ZEB1-dependent. High LAMC2 was significantly correlated with the mesenchymal marker vimentin expression in lung adenocarcinomas, and with higher risk of recurrence or death in patients with lung adenocarcinoma. We suggest that LAMC2 promotes metastasis in lung adenocarcinoma via EMT and may be a potential therapeutic target.

The metastasis-associated molecule C4.4A promotes tissue invasion and anchorage independence by associating with the alpha6beta4 integrin

C4.4A is a metastasis-associated molecule that functions appear to rely on associated alph6beta4 integrin. To corroborate the impact of the C4.4A-alpha6beta4 integrin association on metastasis formation, C4.4A was knocked-down in a highly metastatic rat pancreatic adenocarcinoma (ASML, ASML-C4.4Akd). Metastasis formation by ASML-C4.4Akd cells after intrafootpad application was strongly retarded in draining nodes and lung colonization was rare. Furthermore, cisplatin treatment significantly prolonged the survival time only of ASML-C4.4Akd-bearing rats. ASML-C4.4Akd cells display reduced migratory activity and impaired matrix protein degradation due to inefficient MMP14 activation; loss of drug-resistance is due to mitigated PI3K/Akt pathway activation. These losses of function rely on the laminin receptor C4.4A recruiting activated alpha6beta4 integrin into rafts, where C4.4A cooperates with alpha6beta4 and via alpha6beta4 with MMP14. Within this raft-located complex, MMP14 provokes focalized matrix degradation and mostly alpha6beta4 integrin promotes BAD phosphorylation and upregulated Bcl2 and BclXl expression. Thus, metastasis-promoting activities of C4.4A are not genuine characteristics of C4.4A. Instead, the raft-located laminin receptor C4.4A recruits alpha6beta4 integrin and supports via the alpha6beta4 integrin MMP14 activation. Thereby C4.4A acts as a linker to facilitate several steps in the metastatic cascade. Taking the restricted C4.4A expression in non-transformed tissue, this knowledge should pave the way toward the use of C4.4A as a therapeutic target.

Epidermal deletion of HIF-2α stimulates wound closure

Wound closure requires a complex series of micro-environmentally influenced events. A key aspect of wound closure is the migration of keratinocytes across the open wound. It has been found previously that the response to hypoxia via the HIF-1α transcription factor is a key feature of wound closure. The need for hypoxic response is likely due to interrupted wound vasculature, as well as infection, and in this work we investigated the need for a highly related hypoxic response transcription factor, HIF-2α. This factor was deleted tissue specifically in mice, and the resulting mice were found to have an accelerated rate of wound closure. This is correlated with a reduced bacterial load and inflammatory response in these mice. This indicates that manipulating or reducing the HIF-2α response in keratinocytes could be a useful means to accelerate wound healing and tissue repair.

Transdifferentiation of alveolar epithelial type II to type I cells is controlled by opposing TGF-β and BMP signaling

Alveolar epithelial type II (ATII) cells are essential for maintaining normal lung homeostasis because they produce surfactant, express innate immune proteins, and can function as progenitors for alveolar epithelial type I (ATI) cells. Although autocrine production of transforming growth factor (TGF)-β1 has been shown to promote the transdifferentiation of primary rat ATII to ATI cells in vitro, mechanisms controlling this process still remain poorly defined. Here, evidence is provided that Tgf-β1, -2, -3 mRNA and phosphorylated SMAD2 and SMAD3 significantly increase as primary cultures of mouse ATII cells transdifferentiate to ATI cells. Concomitantly, bone morphogenetic protein (Bmp)-2 and -4 mRNA, and phosphorylated SMAD1/5/8 expression decrease. Exogenously supplied recombinant human TGF-β1 inhibited BMP signaling and enhanced transdifferentiation by promoting the loss of ATII cell-specific gene expression and weakly stimulating ATI cell-specific gene expression. On the other hand, exogenously supplied recombinant human BMP-4 inhibited TGF-β signaling and delayed transdifferentiation by inhibiting the gain in ATI cell-specific gene expression and weakly delaying the loss of ATII cell-specific gene expression. In mouse lung epithelial (MLE15) cells, small-interfering RNA (siRNA) knockdown of TGF-β receptor type-1 enhanced basal expression of ATII genes while siRNA RNA knockdown of BMP receptors type-1a and -1b enhanced basal expression of ATI genes. Together, these results suggest that the rate of ATII cell transdifferentiation is controlled by the opposing actions of BMP and TGF-β signaling that switch during the process of transdifferentiation.

Autologous keratinocyte suspension in platelet concentrate accelerates and enhances wound healing - a prospective randomized clinical trial on skin graft donor sites: platelet concentrate and keratinocytes on donor sites

Background

Wound healing involves complex mechanisms, which, if properly chaperoned, can enhance patient recovery. The abilities of platelets and keratinocytes may be harnessed in order to stimulate wound healing through the formation of platelet clots, the release of several growth factors and cytokines, and cell proliferation. The aim of the study was to test whether autologous keratinocyte suspensions in platelet concentrate would improve wound healing. The study was conducted at the Lausanne University Hospital, Switzerland in 45 patients, randomized to three different topical treatment groups: standard treatment serving as control, autologous platelet concentrate (PC) and keratinocytes suspended in autologous platelet concentrate (PC + K). Split thickness skin graft donor sites were chosen on the anterolateral thighs of patients undergoing plastic surgery for a variety of defects. Wound healing was assessed by the duration and quality of the healing process. Pain intensity was evaluated at day five.

Results

Healing time was reduced from 13.9 ± 0.5 days (mean ± SEM) in the control group to 7.2 ± 0.2 days in the PC group (P < 0.01). An addition of keratinocytes in suspension further reduced the healing time to 5.7 ± 0.2 days. Pain was reduced in both the PC and PC + K groups. Data showed a statistically detectable advantage of using PC + K over PC alone (P < 0.01).

Conclusion

The results demonstrate the positive contribution of autologous platelets combined with keratinocytes in stimulating wound healing and reducing pain. This strikingly simple approach could have a significant impact on patient care, especially critically burned victims for whom time is of the essence.

Clinical trial registry information

Protocol Record Identification Number: 132/03

Registry URL: http://www.clinicaltrials.gov

Laminin 332 processing impacts cellular behavior

Laminin 332, composed of the α3, β3 and γ2 chains, is an epithelial-basement membrane specific laminin variant. Its main role in normal tissues is the maintenance of epithelial-mesenchymal cohesion in tissues exposed to external forces, including skin and stratified squamous mucosa. After being secreted and deposited in the extracellular matrix, laminin 332 undergoes physiological maturation processes consisting in the proteolytic processing of domains located within the α3 and the γ2 chains. These maturation events are essential for laminin 332 integration into the basement membrane where it plays an important function in the nucleation and maintenance of anchoring structures. Studies in normal and pathological situations have revealed that laminin 332 can trigger distinct cellular events depending on the level of its proteolytic cleavages. In this review, the biological and structural characteristics of laminin 332 domains are presented and we discuss whether they trigger specific functions.

Cell surface proteoglycans syndecan-1 and -4 bind overlapping but distinct sites in laminin α3 LG45 protein domain

Keratinocyte migration during epidermal repair depends on interactions between cellular heparan sulfate proteoglycan receptors, syndecan-1 and -4, and the C-terminal globular domains (LG45) of the extracellular matrix protein laminin 332. This study investigates the molecular basis of the binding specificity of the syndecan-1 and -4 receptors expressed by human keratinocytes. We used site-directed mutagenesis to alter a recombinant LG45 protein by substituting the most critical basic residues with glutamine. All proteins were expressed in mammalian cells, purified, and characterized biochemically. We used in vitro binding assays, including surface plasmon resonance, to examine interactions between mutated LG45 and heparan sulfates, syndecan-1 and -4. We identify a major heparin binding domain on the outer edge of a β-strand of LG45 surrounded by a track of converging low affinity residues. This domain harbors distinctive syndecan-1 and -4 binding-specific sequences. This is the first study to demonstrate a binding specificity of two proteoglycans produced by a single cell type. In addition, we found that although syndecan-1 interacts exclusively through its glycosaminoglycan chains, syndecan-4 binding relies on both its core protein and its heparan sulfate chains. These results suggest that LG45 may trigger different signals toward keratinocytes depending on its interaction with syndecan-1 or -4.

Epithelial integrins with special reference to oral epithelia

Adhesion of epithelium to the extracellular matrix is crucial for the maintenance of systemic and oral health. In the oral cavity, teeth or artificial dental implants penetrate the soft tissue of the gingiva. In this interface, gingival soft tissue needs to be well attached via the epithelial seal to the tooth or implant surface to maintain health. After injury or wounding, epithelial tissue rapidly migrates to form the initial epithelial cover to restore the barrier against infection. These events are crucially dependent on deposition of extracellular matrix and proper activation and function of integrin receptors in the epithelial cells. Recent experimental evidence suggests that epithelial integrins also participate in the regulation of periodontal inflammation. In this review, we will discuss the structure and function of epithelial integrins and their extracellular ligands and elaborate on their potential role in disease and repair processes in the oral cavity.

Collagen XXIII, novel ligand for integrin alpha2beta1 in the epidermis

Cellular receptors for collagens belong to the family of β(1) integrins. In the epidermis, integrin α(2)β(1) is the only collagen-binding integrin present. Its expression is restricted to basal keratinocytes with uniform distribution on the cell surface of those cells. Although α(2)β(1) receptors localized at the basal surface interact with basement membrane proteins collagen IV and laminin 111 and 332, no interaction partners have been reported for these integrin molecules at the lateral and apical membranes of basal keratinocytes. Solid phase binding and surface plasmon resonance spectroscopy demonstrate that collagen XXIII, a member of the transmembrane collagens, directly interacts with integrin α(2)β(1) in an ion- and conformation-dependent manner. The two proteins co-localize on the surface of basal keratinocytes. Furthermore, collagen XXIII is sufficient to induce adhesion and spreading of keratinocytes, a process that is significantly reduced in the absence of functional integrin α(2)β(1).

Delayed re-epithelialization in periostin-deficient mice during cutaneous wound healing

Background

Matricellular proteins, including periostin, are important for tissue regeneration.

Methods and Findings

Presently we investigated the function of periostin in cutaneous wound healing by using periostin-deficient (−/−) mice. Periostin mRNA was expressed in both the epidermis and hair follicles, and periostin protein was located at the basement membrane in the hair follicles together with fibronectin and laminin γ2. Periostin was associated with laminin γ2, and this association enhanced the proteolytic cleavage of the laminin γ2 long form to produce its short form. To address the role of periostin in wound healing, we employed a wound healing model using WT and periostin−/− mice and the scratch wound assay in vitro. We found that the wound closure was delayed in the periostin−/− mice coupled with a delay in re-epithelialization and with reduced proliferation of keratinocytes. Furthermore, keratinocyte proliferation was enhanced in periostin-overexpressing HaCaT cells along with up-regulation of phosphorylated NF-κB.

Conclusion

These results indicate that periostin was essential for keratinocyte proliferation for re-epithelialization during cutaneous wound healing.

Collagen IV significantly enhances migration and transplantation of embryonic stem cells: involvement of α2β1 integrin-mediated actin remodeling

Embryonic stem (ES) cell transplantation represents a potential means for the treatment of degenerative diseases and injuries. As appropriate distribution of transplanted ES cells in the host tissue is critical for successful transplantation, the exploration of efficient strategies to enhance ES cell migration is warranted. In this study we investigated ES cell migration under the influence of various extracellular matrix (ECM) proteins, which have been shown to stimulate cell migration in various cell models with unclear effects on ES cells. Using two mouse ES (mES) cell lines, ESC 26GJ9012-8-2 and ES-D3 GL, to generate embryoid bodies (EBs), we examined the migration of differentiating cells from EBs that were delivered onto culture surfaces coated with or without collagen I, collagen IV, Matrigel, fibronectin, and laminin. Among these ECM proteins, collagen IV exhibited maximal migration enhancing effect. mES cells expressed α2 and β1 integrin subunits and the migration enhancing effect of collagen IV was prevented by RGD peptides as well as antibodies against α2 and β1 integrins, indicating that the enhancing effect of collagen IV on cell migration was mediated by α2β1 integrin. Furthermore, staining of actin cytoskeleton that links to integrins revealed well-developed stress fibers and long filopodia in mES cells cultured on collagen IV, and the actin-disrupting cytochalasin D abolished the collagen IV-enhanced cell migration. In addition, pretreatment of undifferentiated or differentiated mES cells with collagen IV resulted in improved engraftment and growth after transplantation into the subcutaneous tissue of nude mice. Finally, collagen IV pretreatment of osteogenically differentiated mES cells increased osteogenic differentiation-like tissue and decreased undifferentiation-like tissue in the grafts grown after transplantation. Our results demonstrated that collagen IV significantly enhanced the migration of differentiating ES cells through α2β1 integrin-mediated actin remodeling and could promote ES cell transplantation efficiency, which may be imperative to stem cell therapy.

Anoikis mediators in oral squamous cell carcinoma

Anoikis - apoptotic cell death triggered by loss of extracellular matrix (ECM) contacts - is dysregulated in many chronic debilitating and fatal diseases. Mechanisms rendering tumor cells resistant to anoikis, although not completely understood, possess significant therapeutic promise. In death receptor-mediated anoikis mechanisms, focal adhesion kinase (FAK) and receptor-interacting protein (RIP) dissociate, leading to association of RIP with Fas, formation of the death-inducing signaling complex (DISC), activation of caspase-3, and propagation of anoikis. In contrast, anoikis resistance is accomplished through constitutive activation of survival pathways that include integrin-dependent activation of FAK and extracellular-signal-regulated kinase (ERK). In addition, FAK and RIP association confers anoikis resistance by inhibiting the association of RIP with Fas and formation of the death signaling complex, which allows cells to escape anoikis. Up-regulation of CD44 also contributes to survival signals and promotes anoikis resistance. This review will focus on the roles of death receptors, prosurvival pathways, and the molecular players involved in anoikis escalation and resistance in oral squamous cell carcinoma.

Expression of laminin gamma2 chain monomer enhances invasive growth of human carcinoma cells in vivo

Laminin gamma2 chain is a subunit of the heterotrimeric basement membrane protein laminin-332 (alpha3beta3gamma2). The gamma2 chain is highly expressed by human cancers at the invasion fronts and this expression correlates with poor prognosis of the cancers. Our previous study showed that the gamma2 chain is expressed as a monomer form in invading carcinoma cells. However, the role of the gamma2 protein in tumor invasion remains unknown. Here, we demonstrate that the monomeric gamma2 chain promotes invasive growth of human cancer cells in vivo. First, we analyzed regulatory factors for the gamma2 chain expression using 2 gastric carcinoma cell lines. It was found that tumor necrosis factor-alpha, by itself or in a combination with transforming growth factor-beta1, strongly induced the secretion of the monomeric gamma2 chain. In addition, epidermal growth factor families appeared to function as the gamma2 chain inducers in human cancers. Next, we established T-24 bladder carcinoma cell lines expressing the full-length or the short arm of the laminin gamma2 chain. When these cell lines were i.p. injected into nude mice, they produced larger tumors in the abdominal cavity and showed much stronger invasive growth onto the diaphragms than the control cell line. The gamma2-expressing T-24 cells often produced ascites fluid, but scarcely the control cells. In culture, the gamma2-expressing cells migrated through Matrigel more efficiently than the control cells. These findings imply that the gamma2 monomer is induced in human cancers by inflammatory and stromal cytokines and promotes their invasive growth in vivo.

Antibodies blocking adhesion and matrix binding domains of laminin-332 inhibit tumor growth and metastasis in vivo

Laminin-332 (LN-332), which is essential for epithelial cell adhesion and migration, is up-regulated in most invasive carcinomas. Association between LN-332 and carcinoma cell integrins and stroma collagen is thought to be important for tumor growth and metastasis. Here, we show that function blocking LN-332 antibodies interfering with cellular adhesion and migration in vitro evoke apoptotic pathways. The antibodies also target epithelial tumors in vivo. Antibodies against the cell binding domain of the alpha3 chain of LN-332 inhibited tumor growth by up to 68%, and antibodies against the matrix binding domains of the beta3 and gamma2 chains significantly decreased lung metastases. The LN-332 antibodies appear to induce tumor cell anoikis and subsequent programmed cell death and reduce migration by interfering with tumor cell matrix interactions.

Defining the role of laminin-332 in carcinoma

The deadly feature of cancer, metastasis, requires invasion of cells through basement membranes (BM), which normally act as barriers between tissue compartments. In the case of many epithelially-derived cancers (carcinomas), laminin-332 (Ln-332) is a key component of the BM barrier. This review provides a historical examination of Ln-332 from its discovery through identification of its functions in BM and possible role in carcinomas. Current understanding points to distinct roles for the three Ln-332 subunits (alpha3, beta3, gamma2) in cell adhesion, extracellular matrix stability, and cell signaling processes in cancer. Given the large number of studies linking Ln-332 gamma2 subunit with cancer prognosis, particular attention is given to the crucial role of this subunit in cancer invasion and to the unanswered questions in this area.

Lamininα3 LG4 Module Induces Keratinocyte Migration: Involvement of Matrix Metalloproteinase-9

Laminin alpha3 chain, a functionally key subunit of laminin-5, contains a large globular module (G module) which consists of a tandem repeat of five homologous LG modules (LG1-5). We previously demonstrated that the LG4 module of laminin alpha3 chain (alpha3 LG4) induces a matrix metalloproteinase-1 (MMP-1) expression through the interaction with syndecans leading to MAPK activation/IL-1beta expression signaling loop (Utani et al., J. Biol. Chem. 278, 34483-34490, 2003). Here, we show that a recombinant alpha3 LG4 and synthetic peptides containing syndecan binding motif induced a cell motility and a MMP-9 expression in ketarinocytes. The synthetic peptide (A3G756)-induced cell migration and MMP-9 upregulation were inhibited by each application of a heparin and an IL-1 receptor antagonist (IL-1RA), suggesting the involvement of syndecans and IL-1beta autocrine. Furthermore, the A3G756-induced cell motility was inhibited by an MMP-9 inhibitor and a neutralizing antibody of MMP-9, indicating induced cell motility was dependent on an MMP-9 activity. Taken these together, laminin-5 alpha3 LG4 module may play an important role in re-epithelialization at tissue remodeling.

Laminin-332 and -511 in skin

The extracellular matrix (ECM) was long thought to be merely a structural tissue support and/or a filter. However, recent studies have suggested that ECM proteins regulate many intracellular and extracellular events, including cell growth, cell adhesion, cell division, cell movement, and apoptosis. They do so through activation of several families of cell surface receptor, including the integrins and syndecans. The focus of this review is on two laminin isoforms expressed in the skin. Laminins are an important molecular component of the basement membranes in a variety of tissue types. They have a cruciform shape, and are composed of three chains-alpha, beta, and gamma. Keratinocytes of the skin secrete numerous laminin isoforms, including laminin-511 and laminin-332. The latter are known to affect the behaviour of keratinocytes through binding to membrane-penetrating receptors (outside-in signal transduction). Conversely, the expression, secretion and assembly of laminin-rich matrices is regulated by cell surface receptors through inside-out signal transduction. We will review how integrins regulate laminin matrix assembly and the signals elicited by laminins that support either migration or stable adhesion of keratinocytes. We will also discuss recent data indicating that laminins plays key regulatory roles in the development of skin appendages and contribute to the pathogenesis of skin cancer.

Laminin-332 promotes the invasion of oesophageal squamous cell carcinoma via PI3K activation

Laminin-332 is major component of epithelial basement membrane, and has an important role in cell migration and tumour invasion. Recently, the phosphatidylinositol 3-kinase (PI3K) activation induced by laminin-332 during carcinogenesis or tumour invasion has been highlighted in skin squamous cell carcinoma. The expression of laminin-332 in 126 resected oesophageal squamous cell carcinoma (ESCC) specimens was immunohistochemically examined to determine its associations with the clinicopathological characteristics, and the effect of laminin-332 on the invasiveness and the PI3K activation was assessed by in vitro experiments using ESCC cell lines (ESCCs). Sections with immunostaining signals in >30% cancer cells, which were observed in 55 of 126 cases, were judged to be positive for laminin-332. The positivity was significantly correlated with pTNM stage and poor prognosis. Inactivation of the PI3K pathway by laminin-332 blocking antibody suppressed the invasiveness of TE8 cell line, which secreted laminin-332 at high level and had high PI3K activity. The addition of the purified laminin-332 activated the PI3K pathway and increased the invasiveness of TE11 cell line, which secreted laminin-332 at lower level and had low PI3K activity. The deactivation of PI3K pathway using the PI3K inhibitor decreased the invasiveness of ESCCs and the secretion of laminin-332 in vitro. The expression of laminin-332 was one of the prognostic factors of ESCC. Laminin-332 could provide the autocrine positive-feedback loop through PI3K activation, contributing the invasive ability. Therefore, the inhibitor of PI3K pathway might be useful as the anticancer therapies for ESCC.

Syndecan-1 interaction with the LG4/5 domain in laminin-332 is essential for keratinocyte migration

Laminin 5/laminin 332 (LN332) is an adhesion substrate for epithelial cells. After secretion of LN332, a regulated cleavage occurs at the carboxy-terminus of its alpha3 subunit, which releases a tandem of two globular modules named LG4/5. We show that the presence of the LG4/5 domain in precursor LN332 decreases its integrin-mediated cell adhesion properties in comparison with mature LN332. Whereas cell adhesion to the recombinant LG4/5 fragment relies solely on the heparan sulfate proteoglycan (HSPG) receptor syndecan-1, we reveal that both syndecan-1 and the alpha3beta1 integrin bind to precursor LN332. We further demonstrate that syndecan-1 mediated cell adhesion to the LG4/5 fragment and pre-LN332 allows the formation of fascin-containing protrusions, depending on the GTPases Rac and Cdc42 activation. Reducing syndecan-1 expression in normal keratinocytes prevents cell protrusions on pre-LN332 with subsequent failure of the peripheral localization of the alpha3beta1 integrin. We finally show that cell migration on pre-LN332 requires syndecan-1. Therefore, the LG4/5 domain in precursor LN332 appears to trigger intracellular signaling events, which participate in keratinocyte motility.

Laminin-332-integrin interaction: a target for cancer therapy?

For many years, extracellular matrix (ECM) was considered to function as a tissue support and filler. However, we now know that ECM proteins control many cellular events through their interaction with cell-surface receptors and cytoplasmic signaling pathways. For example, they regulate cell proliferation, cell division, cell adhesion, cell migration, and apoptosis. We focus in this review on a laminin isoform, laminin-332 (formerly termed laminin-5), a major component of the basement membrane (BM) of skin and other epithelial tissues. It is composed of 3 subunits (alpha3beta3 and gamma3 and interacts with at least two integrin receptors expressed by epithelial cells (alpha3beta1 and alpha6beta4 integrin. Mutations in either laminin-332 or integrin alpha6beta4 result in junctional epidermolysis bullosa, a blistering skin disease, while targeting of laminin-332 by autoantibodies in cicatricial pemphigoid leads to dysadhesion of epithelial cells from their underlying connective tissue. Abnormal expression of laminin-332 and its integrin receptors is also a hallmark of certain tumor types and is believed to promote invasion of colon, breast and skin cancer cells. Moreover, there is emerging evidence that laminin-332 and its protease degradation products are not only found at the leading front of several tumors but also likely induce and/or promote tumor cell migration. Thus, in this review, we focus specifically on the role of laminin-332 and its integrin receptors in adhesion, proliferation, and migration/invasion of cancer cells. Finally, we discuss strategies for the development of laminin-332-based antagonists for the treatment of malignant tumors.

Immunohistochemical profile of integrins in enlarged dental follicles and dentigerous cysts

OBJECTIVE AND STUDY DESIGN

The morphological distinction between incipient dentigerous cyst (IDC) and enlarged pericoronal dental follicle (EDF) remains one of the most controversial questions in the literature. The objective of this study was to analyze the immunohistochemistry expression of alfa(2)beta(1), alfa(3)beta(1), and alfa(5)beta(1) in 23 cases of EDFs and 21 cases of IDCs.

RESULTS

All integrins were immunopositive in the cases studied. A significant difference was detected regarding alfa(2)beta(1) integrin (P < .0001) in which a higher expression was present in IDCs. Moreover, statistical difference was also found between basal and suprabasal cell layer in cystic epithelium (P < .0034). The alfa(3)beta(1) integrin expression showed significant difference (P < .013) between EDF and IDC with a tendency of more pronounced staining in IDC.

CONCLUSIONS

These results corroborate the possibility of histopathological distinction between EDF and IDC in which squamous metaplasia of reduced enamel epithelium to stratified epithelium would be the first event of cystic transformation.

The extracellular matrix in wound healing: a closer look at therapeutics for chronic wounds

Disappointing results with the use of exogenous recombinant growth factors in chronic wounds have redirected the focus to the extracellular matrix (ECM). Newer research has clearly changed our view on the role of the ECM in tissue repair and dismissed the dogma that the sole function of ECM is a passive physical support for cells. It is now clear that intact or fragmented ECM molecules are capable of transducing signals pivotal for cell processes in wound healing primarily via integrin interactions in concert with growth factor activation. In addition, our knowledge about ECM molecules in minute concentrations with biological activity, but devoid of significant structural influence, is increasing. This article reviews the multifaceted molecular roles of ECM in the normal wound-healing process and some molecular abnormalities in chronic wounds, and touches on potential therapies based on the developments of tissue biology.

Cell adhesion molecules, the extracellular matrix and oral squamous carcinoma

Carcinomas are characterized by invasion of malignant cells into the underlying connective tissue and migration of malignant cells to form metastases at distant sites. These processes require alterations in cell-cell and cell-extracellular matrix interactions. As cell adhesion molecules play a role in cell-cell and cell-extracellular matrix adhesion and interactions they are involved in the process of tumour invasion and metastases. In epithelial tissues, receptors of the integrin family mediate adhesion to the adjacent matrix whereas cadherins largely mediate intercellular adhesion. These and other cell adhesion molecules such as intercellular adhesion molecule-1, CD44, dystroglycans and selectins, are involved and undergo changes in carcinomas, which provide possible targets for anti-cancer drug treatments. In the extracellular matrix that is associated with tumours, laminin 5, oncofetal fibronectin and tenascin C appear. The degree of expression of some of these moieties indicates prognosis in oral cancer and offer targets for antibody-directed radiotherapy. Metalloproteases which degrade the extracellular matrix are increased in carcinomas, and their activity is necessary for tumour angiogenesis and consequent invasion and metastases. Metalloprotease inhibitors have begun to produce decreases in mortality in clinical trials. This report provides a brief overview of our current understanding of cell adhesion molecules, the extracellular matrix, tumour invasion and metastasis.

G alpha(q/11)-coupled P2Y2 nucleotide receptor inhibits human keratinocyte spreading and migration

Reepithelialization is a critical step in wound healing. It is initiated by keratinocyte migration at the wound edges. After wounding, extracellular nucleotides are released by keratinocytes and other skin cells. Here, we report that activation of P2Y2 nucleotide receptor by ATP/UTP inhibits keratinocyte cell spreading and induces lamellipodium withdrawal. Kymography analysis demonstrates that these effects correlate with a durable decrease of lamellipodium dynamics. P2Y2 receptor activation also induces a dramatic dismantling of the actin network, the loss of alpha3 integrin expression at the cell periphery, and the dissolution of focal contacts as indicated by the alteration of alpha(v) integrins and focal contact protein distribution. In addition, activation of P2Y2R prevents growth factor-induced phosphorylation of Erk(1,2) and Akt/PkB. The use of a specific pharmacological inhibitor (YM-254890), the depletion of G alpha(q/11) by siRNA, or the expression of a constitutively active G alpha(q/11) mutant (Q209L) show that activation of G alpha(q/11) is responsible for these ATP/UTP-induced effects. Finally, we report that ATP delays growth factor-induced wound healing of keratinocyte monolayers. Collectively, these findings provide evidence for a unique and important role for extracellular nucleotides as efficient autocrine/paracrine regulators of keratinocyte shape and migration during wound healing.

Tumour microenvironment: laminin 332 in squamous-cell carcinoma

Basement membranes can be a barrier to tumour growth, but basement membrane molecules, including laminins, are also important autocrine factors produced by cancers to promote tumorigenesis. Many studies have shown the importance of laminin 332 (previously known as laminin 5) in this process, especially in squamous cell carcinoma. Through interactions with several cell-surface receptors (including alpha6beta4 and alpha3beta1 integrins, epidermal growth factor receptor and syndecan 1) and other basement membrane components (including type VII collagen), laminin 332 drives tumorigenesis through phosphatidylinositol-3 kinase (PI3K) and RAC1 activation, promoting tumour invasion and cell survival. The extracellular interactions of laminin 332 appear amenable to antibody-mediated therapies.

Revertant mosaicism in junctional epidermolysis bullosa due to multiple correcting second-site mutations in LAMB3

Revertant mosaicism due to in vivo reversion of an inherited mutation has been described in the genetic skin disease epidermolysis bullosa (EB) for the genes KRT14 and COL17A1. Here we demonstrate the presence of multiple second-site mutations, all correcting the germline mutation LAMB3:c.628G-->A;p.E210K, in 2 unrelated non-Herlitz junctional EB patients with revertant mosaicism. Both probands had a severe reduction in laminin-332 expression in their affected skin. Remarkably, the skin on the lower leg of patient 078-01 (c.628G-->A/c.1903C-->T) became progressively clinically healthy, with normal expression of laminin-332 on previously affected skin. In the other proband, 029-01 (c.628G-->A/c.628G-->A), the revertant patches were located at his arms, shoulder, and chest. DNA analysis showed different second-site mutations in revertant keratinocytes of distinct biopsy specimens (c.565-3T-->C, c.596G-->C;p.G199A, c.619A-->C;p.K207Q, c.628+42G-->A, and c.629-1G-->A), implying that there is not a single preferred mechanism for the correction of a specific mutation. Our data offer prospects for EB treatment in particular cases, since revertant mosaicism seems to occur at a higher frequency than expected. This opens the possibility of applying revertant cell therapy in mosaic EB of the LAMB3 gene by using autologous naturally corrected keratinocytes, thereby bypassing the recombinant gene correction phase.