The basement membrane protein laminin-5 acts as a soluble cell motility factor

Polymeric immunoglobulin receptor suppresses colorectal cancer through the AKT-FOXO3/4 axis by downregulating LAMB3 expression

Colorectal cancer (CRC) remains one of the most common malignancies worldwide and its mechanism is unclear. Polymeric immunoglobulin receptor (PIGR) which plays an important role in mucosal immunity is widely expressed in the mucosal epithelium and is dysregulated in different tumors. However, the role and underlying mechanisms of PIGR in CRC remain unclear. Here, we demonstrated that PIGR was hypermethylated and downregulated in our cohort (N = 272), and these features were associated with reduced overall survival in patients (HRmethylation 1.61, 95% CI [1.11-2.33]). These findings were validated by external TCGA and GEO data. Moreover, PIGR overexpression inhibits CRC cell malignant phenotypes in vitro and impedes CRC cells growth in male BALB/c nude mice. Mechanistically, PIGR physically associates with RE1 silencing transcription factor (REST) and blocks the transcription of laminin subunit beta 3 (LAMB3). Subsequently, the AKT-FOXO3/4 axis was suppressed by downregulated LAMB3. In the drug sensitive assay, PIGR-overexpressing cells were more sensitive to cisplatin and gemcitabine. Together, PIGR may serve as a powerful prognostic biomarker and putative tumor suppressor by suppressing the AKT-FOXO3/4 axis by downregulating LAMB3 in CRC. Our study may offer a novel therapeutic strategy for treating CRC patients who highly express PIGR with cisplatin and gemcitabine.

Epithelial-Mesenchymal Plasticity in Tumor Immune Evasion

Epithelial-mesenchymal transition (EMT) is a fundamental process that occurs during embryogenesis and tissue repair. However, EMT can be hijacked by malignant cells, where it may promote immune evasion and metastasis. Classically considered a dichotomous transition, EMT in cancer has recently been considered a plastic process whereby malignant cells display and interconvert among hybrid epithelial/mesenchymal (E/M) states. Epithelial-mesenchymal plasticity (EMP) and associated hybrid E/M states are divergent from classical EMT, with unique immunomodulatory effects. Here, we review recent insights into the EMP-immune cross-talk, highlighting possible mechanisms of immune evasion conferred by hybrid E/M states and roles of immune cells in EMP.

Assessment of White Spot Lesion and Enamel Demineralization in Orthodontic Patients With Fixed Brackets—A Clinical Appraisal Using Fluoride Mouth Rinse, Fluoride Varnish Containing CPP-ACP, and CPP-ACFP

Purpose:

Efficacy evaluation of casein phosphopeptide amorphous calcium phosphate complex (CPP-ACP), casein phosphopeptide amorphous calcium fluoride phosphate complex (CPP-ACFP), fluoride mouthrinse, and fluoride containing toothpaste as compared to control group for the remineralization of white spot lesions (WSLs) in orthodontic patients with fixed brackets in an in vivo study.

Methods:

Seventy-five subjects with WSL determined by DIAGNOdent were randomly divided into 5 groups. The WSLs DIAGNOdent values for 0, 3, 6, 9, and 12 months were tabulated and subjected to statistical analysis.

Results:

Among the groups, the remineralizing potential of fluoride mouth rinse, fluoride containing toothpaste, and CPP-ACP were similar; however, CPP-ACFP value was superior in comparison to all other groups.

Conclusion:

The CPP-ACFP technique is highly beneficial for the remineralization of WSL in an orthodontic patient when compared to fluoride mouth rinse, fluoride-containing toothpaste, and CPP-ACP paste.

Gene Expression in Amnion-Derived Cells Cultured on Recombinant Laminin 332-A Preliminary Study

Human amniotic cells (hAC) exhibit characteristics of undifferentiated cells and immunomodulatory properties. Recognition of the relationship between amniotic cells and components of the extracellular matrix is an important condition for their ex vivo preparation and further successful clinical application in regenerative medicine and transplantology. Laminin 332 (LN-332), as a natural component of the basement membrane of amniotic epithelial cells and a ligand for integrin receptors, may strongly influence the phenotype and fate of amniotic cells. We investigated the impact of recombinant LN-332 on hAC viability and expression of markers for pluripotency, early differentiation, adhesion, and immunomodulatory properties. During 14 days of culture, hAC were quantified and qualified by light microscopy, immunohistochemistry, immunocytochemistry, and flow cytometry. Gene expression was assessed with real-time polymerase chain reaction (RT-PCR) arrays and compared with differentiated cells originated from the three germ layers. LN-332 caused an over 2-fold increase in the total number of hAC, accompanied by a 75% reduction of SSEA-4-positive cells and an increase in HLA-ABC-positive cells. In particular, we observed that the presence of laminin 332 in the medium of a short-time culture modifies the effect of culture duration on hAC, enhancing time-dependent inhibition of expression of certain genes, including pluripotency and differentiation markers, laminin 332 subunits (which may be part of self-regulation of LN-332 synthesis by amniotic cells), and integrins. The changes observed in hAC were more distinct with respect to differentiated mesenchymal cells, resulting in more comparable phenotypes than those represented by differentiated endo- and ectodermal cells. We concluded that laminin 332 present in the culture medium influences to a certain extent proliferation, adhesion, and differentiation of amniotic cells in culture.

Laminin 332 in cancer: When the extracellular matrix turns signals from cell anchorage to cell movement

Laminin 332 is crucial in the biology of epithelia. This large extracellular matrix protein consists of the heterotrimeric assembly of three subunits - α3, β3, and γ2 - and its multifunctionality relies on a number of extracellular proteolytic processing events. Laminin 332 is central to normal epithelium homeostasis by sustaining cell adhesion, polarity, proliferation, and differentiation. It also supports a major function in epithelial tissue formation, repair, and regeneration by buttressing cell migration and survival and basement membrane assembly. Interest in this protein increased after the discovery that its expression is perturbed in tumor cells, cancer-associated fibroblasts, and the tumor microenvironment. This review summarizes current knowledge regarding the established involvement of the laminin 332 γ2 chain in tumor invasiveness and discusses the role of its α3 and β3 subunits.

Comparative Analysis of the Biosimilar and Innovative G-CSF Modulated Pathways on Umbilical Cord Blood-Derived Mononuclear Cells

Biosimilars of granulocyte colony-stimulating factor (G-CSF) have been routinely introduced into clinical practice. However, not functional genomics characterization has been performed yet in comparison with the innovator G-CSF. This study aimed to evaluate the transcriptomic changes in an in vitro model of umbilical cord blood cells (UBC) exposed to G-CSF for the identification of their modulated pathways. Umbilical cord blood cells-derived mononuclear cells (MNCs) were treated with biosimilar and innovator G-CSF for further gene expression profiling analysis using a microarray-based platform. Comparative analysis of biosimilar and innovator G-CSF gene expression signatures allowed us to identify the most commonly modulated pathways by both drugs. In brief, we observed predominantly upmodulation of transcripts related to PI3K-Akt, NF-kappaB, and tumor necrosis factor (TNF) signaling pathways as well as transcripts related to negative regulation of apoptotic process among others. In addition, hematopoietic colony-forming cell assays corroborate the G-CSF phenotypic effects over UBC-derived MNCs. In conclusion, our study suggests that G-CSF impacts UBC-derived cells through the modulation of several signaling pathways associated with cell survival, migration, and proliferation. The concordance observed between biosimilar and innovator G-CSF emphasizes their similarity in regards to their specificity and biological responses.

LAMC2 modulates the acidity of microenvironments to promote invasion and migration of pancreatic cancer cells via regulating AKT-dependent NHE1 activity

LAMC2, as a unique chain in the Laminin 5 molecule, has been found to be associated with malignant metastases in some cancers. However, the roles and mechanisms by which LAMC2 affects the migration and invasion of pancreatic cancer cells remain unclear. First, we found that laminin 5/LAMC2 and its receptors were highly expressed in pancreatic cancer tissues and cells. Then, we investigated the effects of LAMC2 on pancreatic cancer cell migration/invasion and extracellular (pHe). We also demonstrated that LAMC2 phosphorylated Akt-Ser473 to promote the expression, activity and cell membrane accumulation of NHE1 within pancreatic cancer cells. So we speculated that LAMC2 modulated the pHe to promote migration and invasion of pancreatic cancer cells. Additionally, our data also showed that LAMC2/NHE1 resulted in altered cell morphology and aberrant expression of mesenchymal markers. The function of actin-binding proteins (ABPs) were affected by LAMC2/NHE1 signaling. LAMC2/NHE1 signaling generated extracellular acidification to induce dynamic actin-dependent pseudopodial formation and EMT programs that promote tumor cell invasion in pancreatic cancer cells. Therefore, we found that LAMC2 was responsible for generating the extracellular acidic conditions that mediated invasion of pancreatic cancer cells by activating Akt/NHE1 signaling. LAMC2 is a characteristic prognostic and therapeutic agent of PDCA.

The Tumor Microenvironment: Focus on Extracellular Matrix

The extracellular matrix (ECM) regulates the development and maintains tissue homeostasis. The ECM is composed of a complex network of molecules presenting distinct biochemical properties to regulate cell growth, survival, motility, and differentiation. Among their components, proteoglycans (PGs) are considered one of the main components of ECM. Its composition, biomechanics, and anisotropy are exquisitely tuned to reflect the physiological state of the tissue. The loss of ECM's homeostasis is seen as one of the hallmarks of cancer and, typically, defines transitional events in tumor progression and metastasis. In this chapter, we discuss the types of proteoglycans and their roles in cancer. It has been observed that the amount of some ECM components is increased, while others are decreased, depending on the type of tumor. However, both conditions corroborate with tumor progression and malignancy. Therefore, ECM components have an increasingly important role in carcinogenesis and this leads us to believe that their understanding may be a key in the discovery of new anti-tumor therapies. In this book, the main ECM components will be discussed in more detail in each chapter.

Overexpression of α3, β3 and γ2 chains of laminin-332 is associated with poor prognosis in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDA) is a worldwide health problem. Early diagnosis and assessment may enhance the quality of life and survival of patients. The present study investigated the potential correlations between the gene and protein expression of laminin-332 (LM-332 or laminin-5) and clinicopathological factors as well as evaluating its influence on the survival of patients with PDA. The expression of LM-332 subunit mRNAs in pancreatic carcinoma specimens from 37 patients was investigated by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis. Using immunohistochemical methods, the protein expressions of the three chains of LM-322 (LNα3, LNβ3 and LNγ2) were determined in 96 pancreatic carcinoma specimens, for association analysis with clinicopathological characteristics from patient data. The results of the prognosis analysis of three mRNAs expression datasets were validated in The Cancer Genome Atlas datasets. RT-qPCR results indicated that the overall relative values of LNα3 and LNγ2 mRNAs were increased in pancreatic carcinoma compared with the control. In immunostaining analyses LNα3 and LNγ2 expression was observed in all tumor tissues from the 96 patient samples. The expression levels of LNα3, LNβ3 and LNγ2 were associated with each other. LNα3 and LNγ2 positivity was significantly associated with differentiation, depth of invasion and advanced stage (P<0.05). The samples were classified into three groups: Basement membrane (B) type, cytoplasmic (C) type and mixed (M) type, according to their LNγ2 immunohistochemical expression patterns. The B type correlated significantly with differentiation (P=0.010) and the M type was significantly associated with hepatic metastasis (P=0.031). Patients with B-type LNγ2 demonstrated significantly better outcomes than patients with the C or M type (P=0.012 and P=0.003, respectively). Overexpression of the α3, β3 and γ2 chains of LM-332 may serve an important role in the progression and prognosis of PDA.

β4-Integrin/PI3K Signaling Promotes Tumor Progression through the Galectin-3-N-Glycan Complex

Malignant transformation is associated with aberrant N-glycosylation, but the role of protein N-glycosylation in cancer progression remains poorly defined. β4-integrin is a major carrier of N-glycans and is associated with poor prognosis, tumorigenesis, and metastasis. Here, N-glycosylation of β4-integrin contributes to the activation of signaling pathways that promote β4-dependent tumor development and progression. Increased expression of β1,6GlcNAc-branched N-glycans was found to be colocalized with β4-integrin in human cutaneous squamous cell carcinoma tissues, and that the β1,6GlcNAc residue was abundant on β4-integrin in transformed keratinocytes. Interruption of β1,6GlcNAc-branching formation on β4-integrin with the introduction of bisecting GlcNAc by N-acetylglucosaminyltransferase III overexpression was correlated with suppression of cancer cell migration and tumorigenesis. N-Glycan deletion on β4-integrin impaired β4-dependent cancer cell migration, invasion, and growth in vitro and diminished tumorigenesis and proliferation in vivo The reduced abilities of β4-integrin were accompanied with decreased phosphoinositol-3 kinase (PI3K)/Akt signals and were restored by the overexpression of the constitutively active p110 PI3K subunit. Binding of galectin-3 to β4-integrin via β1,6GlcNAc-branched N-glycans promoted β4-integrin-mediated cancer cell adhesion and migration. In contrast, a neutralizing antibody against galectin-3 attenuated β4-integrin N-glycan-mediated PI3K activation and inhibited the ability of β4-integrin to promote cell motility. Furthermore, galectin-3 knockdown by shRNA suppressed β4-integrin N-glycan-mediated tumorigenesis. These findings provide a novel role for N-glycosylation of β4-integrin in tumor development and progression, and the regulatory mechanism for β4-integrin/PI3K signaling via the galectin-3-N-glycan complex.Implications:N-Glycosylation of β4-integrin plays a functional role in promoting tumor development and progression through PI3K activation via the galectin-3-N-glycan complex. Mol Cancer Res; 16(6); 1024-34. ©2018 AACR.

Upregulated LAMB3 increases proliferation and metastasis in thyroid cancer

Background

Thyroid cancer is the most commonly reported endocrine malignancy, and its increased incidence has been the highest in all human tumors in recent decades. To investigate the mechanism of papillary thyroid cancer (PTC) occurrence and progression, we performed RNA sequencing and found an upregulated gene, LAMB3. However, the biological function of LAMB3 is still not clear.

Materials and methods

We analyzed LAMB3 expression using The Cancer Genome Atlas (TCGA) database and hypothesized LAMB3 to be a gene associated with PTC. To test this hypothesis, we collected 89 pairs of thyroid nodules and adjacent normal thyroid tissues (56 pairs of PTCs, 33 pairs of benign thyroid nodules). Afterward, we performed real-time quantitative polymerase chain reaction (RT-qPCR) to investigate LAMB3 expression in thyroid nodule patients, and then analyzed clinicopathologic features. We performed proliferation, colony formation, migration, and invasion assays to determine the function of LAMB3 in PTC.

Results

We demonstrated that LAMB3 plays oncogenic roles in PTC. The relative expression of LAMB3 is significantly upregulated in PTC compared with matched thyroid normal tissues in validated cohort and TCGA cohort (P<0.001). We also checked area under the curve (AUC of receiver operator characteristic [ROC]) of 97.3% for validated cohort and 90.1% for TCGA cohort to differentiate PTC tumors from normal tissues. In clinicopathologic feature analysis, we found that upregulated LAMB3 is closely related to lymph node metastasis (P=0.018). Furthermore, knockdown of LAMB3 inhibited the proliferation, colony formation, migration, and invasive capacity of PTC.

Conclusion

This study indicated that LAMB3 is a gene associated with PTC.

Roles of Integrin α6β4 Glycosylation in Cancer

Malignant transformation is accompanied with aberrant glycosylation of proteins. Such changes in glycan structure also occur in the integrins, which are a large family of cell surface receptors for the extracellular matrix and play key roles in tumor progression. There is now increasing evidence that glycosylation of integrins affects cellular signaling and interaction with the extracellular matrix, receptor tyrosine kinases, and galectins, thereby regulating cell adhesion, motility, growth, and survival. Integrin α6β4 is a receptor for laminin-332 and the increased expression level is correlated with malignant progression and poor survival in various types of cancers. Recent studies have revealed that integrin α6β4 plays central roles in tumorigenesis and the metastatic process. In this review, we summarize our current understanding of the molecular mechanisms of tumor progression driven by integrin α6β4 and also discuss the modification of glycans on integrin β4 subunit to address the important roles of glycan in integrin-mediated tumor progression.

Epithelial mesenchymal transition related molecular markers and invasion and metastasis of cholangiocarcinoma

Tumor metastasis is a major cause of death in patients with solid tumors. Epithelial mesenchymal transition (EMT) is a process in which the epithelial cells are transformed into the stroma cells. This process is accompanied by changes in gene expression and cell phenotype, which are often activated during tumor invasion and metastasis. Cholangiocarcinoma is a kind of malignancy originating from the bile duct epithelium, and its main biological characteristics are early invasion, metastasis and recurrence. The research of cholangiocarcinoma metastasis could provide a theoretical basis for the development of new treatment strategies to manage this malignancy. This paper reviews the roles of EMT related molecular markers metastasis in the invasion and metastasis of cholangiocarcinoma.

Galectin-3 as a regulator of the epithelial junction: Implications to wound repair and cancer

Epithelial cells are closely connected to each other and to the extracellular matrix by a set of adhesive contacts that provide tissues with unique barrier properties and play a prominent role in cell morphology, tissue physiology, and cell signaling. This review highlights advances made in understanding the contributions of galectin-3, a carbohydrate-binding protein with affinity toward β-galactosides, as a modulator of epithelial junction assembly and function. The interactions of galectin-3 within adhesive structures are discussed in relation to wound healing and tumor progression.

Role of galectins in re-epithelialization of wounds

Re-epithelialization is a critical contributing process in wound healing in the human body. When this process is compromised, impaired or delayed, serious disorders of wound healing may result that are painful, difficult to treat, and affect a variety of human tissues. Recent studies have demonstrated that members of the galectin class of β-galactoside-binding proteins modulate re-epithelialization of wounds by novel carbohydrate-based recognition systems. Galectins constitute a family of widely distributed carbohydrate-binding proteins with the affinity for the β-galactoside-containing glycans found on many cell surface and extracellular matrix (ECM) glycoproteins. There are 15 members of the mammalian galectin family that so far have been identified. Studies of the role of galectins in wound healing have revealed that galectin-3 promotes re-epithelialization of corneal, intestinal and skin wounds; galectin-7 promotes re-epithelialization of corneal, skin, kidney and uterine wounds; and galectins-2 and -4 promote re-epithelialization of intestinal wounds. Promising prospects for developing novel therapeutic strategies for the treatment of problematic, slow- or non-healing wounds are implicit in the findings that galectins stimulate the re-epithelialization of wounds of the cornea, skin, intestinal tract and kidney. Molecular mechanisms by which galectins modulate the process of wound healing are beginning to emerge and are described in this review.

Amino-terminal fragments of laminin γ2 chain retract vascular endothelial cells and increase vascular permeability

Laminin γ2 (Lmγ2) chain, a subunit of laminin-332, is a typical molecular marker of invading cancer cells, and its expression correlates with poor prognosis of cancer patients. It was previously found that forced expression of Lmγ2 in cancer cells promotes their invasive growth in nude mice. However, the mechanism of the tumor-promoting activity of Lmγ2 remains unknown. Here we investigated the interaction between Lmγ2 and vascular endothelial cells. When treated with an N-terminal proteolytic fragment of γ2 (γ2pf), HUVECs became markedly retracted or shrunken. The overexpression of Lmγ2 or treatment with γ2pf stimulated T-24 bladder carcinoma cells to invade into the HUVEC monolayer and enhanced their transendothelial migration in vitro. Moreover, γ2pf increased endothelial permeability in vitro and in vivo. As the possible mechanisms, γ2pf activated ERK and p38 MAPK but inactivated Akt in HUVECs. Such effects of γ2pf led to prominent actin stress fiber formation in HUVECs, which was blocked by a ROCK inhibitor. In addition, γ2pf induced delocalization of VE-cadherin and β-catenin from the intercellular junction. As possible receptors, γ2pf interacted with heparan sulfate proteoglycans on the surface of HUVECs. Moreover, we localized the active site of γ2pf to the N-terminal epidermal growth factor-like repeat. These data suggest that the interaction between γ2pf and heparan sulfate proteoglycans induces cytoskeletal changes of endothelial cells, leading to the loss of endothelial barrier function and the enhanced transendothelial migration of cancer cells. These activities of Lmγ2 seem to support the aberrant growth of cancer cells.

The influence of substrate topography on the migration of corneal epithelial wound borders

Currently available artificial corneas can develop post-implant complications including epithelial downgrowth, infection, and stromal melting. The likelihood of developing these disastrous complications could be minimized through improved formation and maintenance of a healthy epithelium covering the implant. We hypothesize that this epithelial formation may be enhanced through the incorporation of native corneal basement membrane biomimetic chemical and physical cues onto the surface of the keratoprosthesis. We fabricated hydrogel substrates molded with topographic features containing specific bio-ligands and developed an in vitro wound healing assay. In our experiments, the rate of corneal epithelial wound healing was significantly increased by 50% in hydrogel surfaces containing topographic features, compared to flat surfaces with the same chemical attributes. We determined that this increased healing is not due to enhanced proliferation or increased spreading of the epithelial cells, but to an increased active migration of the epithelial cells. These results show the potential benefit of restructuring and improving the surface of artificial corneas to enhance epithelial coverage and more rapidly restore the formation of a functional epithelium.

Aberrant expression of laminin γ2 correlates with poor prognosis and promotes invasion in extrahepatic cholangiocarcinoma

BACKGROUND

To investigate the potential role of laminin γ2 and its correlation with prognosis in patients with extrahepatic cholangiocarcinoma (CCA).

MATERIALS AND METHODS

Laminin γ2 expression was evaluated by immunohistochemistry in 72 extrahepatic CCA patients after surgical resection. Knockdown of laminin γ2 was achieved via small interfering RNA transfection in the extrahepatic CCA cell line QBC939.

RESULTS

Thirty-six of 72 extrahepatic CCAs (50%) stained positive for laminin γ2 in two types of patterns: stromal staining (28/72, 39%) and cytoplasmic staining (24/72, 33%). All 16 paracancerous tissue samples showed negative staining. Both stromal and cytoplasmic laminin γ2 expressions correlated with lymph node metastasis. Kaplan-Meier analysis showed that aberrant expression of laminin γ2 correlated with poor overall survival and early recurrence. Cox regression analysis further demonstrated that laminin γ2 expression was a significant independent predictor of poor overall survival and early recurrence. Immunofluorescence staining revealed cytoplasmic expression of laminin γ2 in QBC939 cells. Knockdown of laminin γ2 significantly reduced QBC939 cell invasion and migration.

CONCLUSIONS

Aberrant expression of laminin γ2 correlates with poor prognosis and promotes invasion in extrahepatic CCA.

Polymerized laminin-332 matrix supports rapid and tight adhesion of keratinocytes, suppressing cell migration

Laminin-332 (α3ß3γ2) (Lm332) supports the stable anchoring of basal keratinocytes to the epidermal basement membrane, while it functions as a motility factor for wound healing and cancer invasion. To understand these contrasting activities of Lm332, we investigated Lm332 matrices deposited by normal human keratinocytes and other Lm332-expressing cell lines. All types of the cells efficiently deposited Lm332 on the culture plates in specific patterns. On the contrary, laminins containing laminin ß1 and/or γ1 chains, such as Lm511 and Lm311, were not deposited on the culture plates even if secreted into culture medium. The Lm332 deposition was not inhibited by function-blocking antibodies to the α3 and α6 integrins but was inhibited by sodium selenate, suggesting that sulfated glycosaminoglycans on cell surface, e.g. heparan sulfate proteoglycans, might be involved in the process. HEK293 cells overexpressing exogenous Lm332 (Lm332-HEK) almost exclusively deposited Lm332 on the plates. The deposited Lm332 matrix showed a mesh-like network structure as analyzed by electron microscopy, suggesting that Lm332 was highly polymerized. When biological activity was analyzed, the Lm332 matrix rather suppressed the migration of keratinocytes as compared with purified Lm332, which highly promoted the cell migration. The Lm332 matrix supported adhesion of keratinocytes much more strongly and stably than purified Lm332. Integrin α3ß1 bound to the Lm332 matrix at a three times higher level than purified Lm332. Normal keratinocytes prominently showed integrin α6ß4-containing, hemidesmosome-like structures on the Lm332 matrix but not on the purified one. These results indicate that the polymerized Lm332 matrix supports stable cell adhesion by interacting with both integrin α6ß4 and α3ß1, whereas unassembled soluble Lm332 supports cell migration.

Partial loss of epithelial phenotype in kindlin-1-deficient keratinocytes

Kindlin-1 is an adaptor protein that is expressed by most epithelial cells and has been implicated in integrin bidirectional signaling. Mutations in the gene encoding kindlin-1 are associated with Kindler syndrome, a recessively inherited disorder that is characterized by fragile skin. Functionally, a loss of kindlin-1 impairs the adhesion of basal keratinocytes to the extracellular matrix both in vivo and in vitro. In this study, we show that the phenotype of mutant keratinocytes deficient in kindlin-1 is characterized by the modification of the cortical actin network and increased plasticity of the plasma membrane. At the molecular level, expression of several proteins associated with an epithelial phenotype, such as α6β4 integrin, collagen XVII, E-cadherin, and desmoglein-3, is strongly reduced, whereas, surprisingly, laminin 332 is synthesized in larger amounts than in control keratinocytes. In contrast, mesenchymal markers such as vimentin and fibronectin are increased in keratinocytes lacking kindlin-1. The switch in cell plasticity and protein expression was confirmed by siRNA-mediated down-regulation of kindlin-1 in HaCaT epithelial cells. Furthermore, there was up-regulation of matrix metalloproteinases and pro-inflammatory cytokines in kindlin-1-deficient keratinocytes. These results provide new insights into the pathogenic mechanisms that take place in Kindler syndrome. Moreover, the constellation of molecular defects associated with the loss of kindlin-1 may explain the higher incidence of skin cancer observed in patients affected with this disorder.

Laminin-332 coordinates mechanotransduction and growth cone bifurcation in sensory neurons

Laminin-332 is a major component of the dermo-epidermal skin basement membrane and maintains skin integrity. The transduction of mechanical force into electrical signals by sensory endings in the skin requires mechanosensitive channels. We found that mouse epidermal keratinocytes produce a matrix that is inhibitory for sensory mechanotransduction and that the active molecular component is laminin-332. Substrate-bound laminin-332 specifically suppressed one type of mechanosensitive current (rapidly adapting) independently of integrin-receptor activation. This mechanotransduction suppression could be exerted locally and was mediated by preventing the formation of protein tethers necessary for current activation. We also found that laminin-332 could locally control sensory axon branching behavior. Loss of laminin-332 in humans led to increased sensory terminal branching and may lead to a de-repression of mechanosensitive currents. These previously unknown functions for this matrix molecule may explain some of the extreme pain experienced by individuals with epidermolysis bullosa who are deficient in laminin-332.

Laminin-111: a potential therapeutic agent for Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) still needs effective treatments, and myoblast transplantation (MT) is considered as an approach to repair damaged skeletal muscles. DMD is due to the complete loss of dystrophin from muscles. The lack of link between the contracting apparatus and the extracellular matrix leads to frequent damage to the sarcolemma triggering muscle fiber necrosis. Laminins are major proteins in the extracellular matrix. Laminin-111 is normally present in skeletal and cardiac muscles in mice and humans but only during embryonic development. In this study, we showed that intramuscular injection of laminin-111 increased muscle strength and resistance in mdx mice. We also used laminin-111 as a coadjuvant in MT, and we showed this protein decreased considerably the repetitive cycles of degeneration, inflammatory reaction, and regeneration. Moreover, MT is significantly improved. To explain the improvement, we confirmed with the same myoblast cell batch that laminin-111 improves proliferation and drastically increases migration in vitro. These results are extremely important because DMD could be treated only by the injection of a recombinant protein, a simple and safe therapy to prevent loss of muscle function. Moreover, the improvement in MT would be significant to treat the muscles of DMD patients who are already weak.

Adhesion and migration, the diverse functions of the laminin alpha3 subunit

The laminins are a secreted family of heterotrimeric molecules essential for basement membrane formation, structure, and function. It is now well established that the alpha3 subunit of laminins-332, -321, and -311 plays an important role in mediating epidermal-dermal integrity and is essential for the skin to withstand mechanical stresses. These laminins also regulate cell migration and mechanosignal transduction. This article provides an overview of the gene, transcripts, and protein structures of laminin alpha3. Also discussed are the proposed functions for the alpha3 subunit-containing laminins.

Cyclic mechanical stretch decreases cell migration by inhibiting phosphatidylinositol 3-kinase- and focal adhesion kinase-mediated JNK1 activation

Epithelial cell migration during wound healing requires coordinated signaling pathways that direct polarization of the leading and trailing ends of the cells, cytoskeletal organization, and remodeling of focal adhesions. These inherently mechanical processes are disrupted by cyclic stretch (CS), but the specific signaling molecules involved in this disruption are not well understood. In this study, we demonstrate that inhibition of phosphatidylinositol 3-kinase (PI3K) or expression of a dominant-negative form of PI3K caused inhibition of airway epithelial cell wound closure. CS caused a sustained decrease in activation of PI3K and inhibited wound healing. Expression of constitutively active PI3K stimulated translocation of Tiam1 to the membrane, increased Rac1 activity, and increased wound healing of airway epithelial cells. Increased Rac1 activity resulted in increased phosphorylation of JNK1. PI3K activation was not regulated by association with focal adhesion kinase. Restoration of efficient cell migration during CS required coexpression of constitutively active PI3K, focal adhesion kinase, and JIP3.

A systems analysis of the chemosensitivity of breast cancer cells to the polyamine analogue PG-11047

BACKGROUND

Polyamines regulate important cellular functions and polyamine dysregulation frequently occurs in cancer. The objective of this study was to use a systems approach to study the relative effects of PG-11047, a polyamine analogue, across breast cancer cells derived from different patients and to identify genetic markers associated with differential cytotoxicity.

METHODS

A panel of 48 breast cell lines that mirror many transcriptional and genomic features present in primary human breast tumours were used to study the antiproliferative activity of PG-11047. Sensitive cell lines were further examined for cell cycle distribution and apoptotic response. Cell line responses, quantified by the GI50 (dose required for 50% relative growth inhibition) were correlated with the omic profiles of the cell lines to identify markers that predict response and cellular functions associated with drug sensitivity.

RESULTS

The concentrations of PG-11047 needed to inhibit growth of members of the panel of breast cell lines varied over a wide range, with basal-like cell lines being inhibited at lower concentrations than the luminal cell lines. Sensitive cell lines showed a significant decrease in S phase fraction at doses that produced little apoptosis. Correlation of the GI50 values with the omic profiles of the cell lines identified genomic, transcriptional and proteomic variables associated with response.

CONCLUSIONS

A 13-gene transcriptional marker set was developed as a predictor of response to PG-11047 that warrants clinical evaluation. Analyses of the pathways, networks and genes associated with response to PG-11047 suggest that response may be influenced by interferon signalling and differential inhibition of aspects of motility and epithelial to mesenchymal transition.

Regulated laminin-332 expression in human islets of Langerhans

Laminin-332 (LN-332) is a basement membrane component known to exert a beneficial effect on rat pancreatic beta cells in vitro. In this work, we analyzed the expression of LN-332 in human islets, its expression after inflammatory insults by cytokines, and the molecular mechanisms responsible for this effect. By Western blotting and RT-PCR, we showed that LN-332 was expressed in isolated human islets. By immunofluorescence on pancreas sections, we observed that labeling was confined to endocrine cells in islets. Confocal microscopy analysis on isolated islet cells revealed that labeling was granular but did not colocalize with hormone secretory granules. LN-332 was most abundant in cultured islets compared to freshly isolated islets and was found in culture medium, which suggests that it was secreted by islets. When islets were exposed to interleukin (IL)-1beta, expression and secretion of LN-332 increased as compared to control. No effect was observed with tumor necrosis factor (TNF)-alpha and interferon (IFN)-gamma. LY294002, an inhibitor of phosphatidylinositol 3-kinase (PI3-K) activity, inhibited culture- and IL-1beta-induced LN-332 expression in islets. These results show that LN-332, known to have some beneficial effect on beta cells in vitro, is produced and secreted by endocrine islet cells and is up-regulated by stressing conditions such as culture and IL-1beta-exposure.

Bisecting GlcNAc residues on laminin-332 down-regulate galectin-3-dependent keratinocyte motility

Laminin-332 (Lm332; formerly laminin-5) is a basement membrane protein in the skin, which promotes cell motility in wound healing and cancer invasion. In a previous study, we reported that the introduction of bisecting GlcNAc into Lm332 (GnT-III-Lm332), catalyzed by N-acetylglucosaminyltransferase III (GnT-III), reduced cell migration (Kariya, Y., Kato, R., Itoh, S., Fukuda, T., Shibukawa, Y., Sanzen, N., Sekiguchi, K., Wada, Y., Kawasaki, N., and Gu, J. (2008) J. Biol. Chem. 283, 33036-33045). However, the underlying molecular mechanism by which GnT-III-Lm332 suppresses the normal biological functions of Lm332 remains to be elucidated. In this study, we show that galectin-3, which is a beta-galactoside-binding protein, strongly bound to unmodified Lm332 but not to GnT-III-Lm332 and that binding of galectin-3 was completely blocked by lactose. Exogenous galectin-3 significantly enhanced keratinocyte cell motility on control Lm332 but not on GnT-III-Lm332. A functional blocking antibody against galectin-3 inhibited Lm332-induced alpha3beta1 and alpha6beta4 integrin clustering and focal contact formation. Co-immunoprecipitation revealed that galectin-3 associated with both beta4 integrin and epidermal growth factor receptor, thereby cross-linking the two molecules. The associations were inhibited by either the presence of lactose or expression of GnT-III. Moreover, galectin-3 consistently enhanced ERK activation. Taken together, the results of this study are the first to clearly identify the molecular mechanism responsible for the inhibitory effects of GnT-III on extracellular matrix-integrin-meditated cell adhesion, migration, and signal transduction. The findings presented herein shed light on the importance of N-glycosylation-mediated supramolecular complex formation on the cell surface.

N-Glycosylation of laminin-332 regulates its biological functions. A novel function of the bisecting GlcNAc

Laminin-332 (Lm332) is a large heterotrimeric glycoprotein that has been identified as a scattering factor, a regulator of cancer invasion as well as a prominent basement membrane component of the skin. Past studies have identified the functional domains of Lm332 and revealed the relationships between its activities and the processing of its subunits. However, there is little information available concerning the effects of N-glycosylation on Lm332 activities. In some cancer cells, an increase of beta1,6-GlcNAc catalyzed by N-acetylglucosaminyltransferase V (GnT-V) is related to the promotion of cancer cell motility. By contrast, bisecting GlcNAc catalyzed by N-acetylglucosaminyltransferase III (GnT-III) suppresses the further processing with branching enzymes, such as GnT-V, and the elongation of N-glycans. To examine the effects of those N-glycosylations to Lm332 on its activities, we purified Lm332s from the conditioned media of GnT-III- and GnT-V-overexpressing MKN45 cells. Lectin blotting and mass spectrometry analyses revealed that N-glycans containing the bisecting GlcNAc and beta1,6-GlcNAc structures were strongly expressed on Lm332 purified from GnT-III-overexpressing (GnT-III-Lm332) and GnT-V-overexpressing (GnT-V-Lm332) cells, respectively. Interestingly, the cell adhesion activity of GnT-III-Lm332 was apparently decreased compared with those of control Lm332 and GnT-V-Lm332. In addition, the introduction of bisecting GlcNAc to Lm332 resulted in a decrease in its cell scattering and migration activities. The weakened activities were most likely derived from the impaired alpha3beta1 integrin clustering and resultant focal adhesion formation. Taken together, our results clearly demonstrate for the first time that N-glycosylation may regulate the biological function of Lm332. This finding could introduce a new therapeutic strategy for cancer.

HIF1 transcription factor regulates laminin-332 expression and keratinocyte migration

Epidermal wound repair is a complex process involving the fine orchestrated regulation of crucial cell functions, such as proliferation, adhesion and migration. Using an in vitro model that recapitulates central aspects of epidermal wound healing, we demonstrate that the transcription factor HIF1 is strongly stimulated in keratinocyte cultures submitted to mechanical injury. Signals generated by scratch wounding stabilise the HIF1alpha protein, which requires activation of the PI3K pathway independently of oxygen availability. We further show that upregulation of HIF1alpha plays an essential role in keratinocyte migration during the in vitro healing process, because HIF1alpha inhibition dramatically delays the wound closure. In this context, we demonstrate that HIF1 controls the expression of laminin-332, one of the major epithelial cell adhesion ligands involved in cell migration and invasion. Indeed, silencing of HIF1alpha abrogates injury-induced laminin-332 expression, and we provide evidence that HIF1 directly regulates the promoter activity of the laminin alpha3 chain. Our results suggest that HIF1 contributes to keratinocyte migration and thus to the re-epithelialisation process by regulating laminin-332.

Role of siRNA silencing of MMP-2 gene on invasion and growth of laryngeal squamous cell carcinoma

The purpose of this study was to explore the effects of MMP-2 silencing on the invasion and growth of laryngeal squamous cell carcinoma (LSCC). Hep-2 cells were transfected with MMP-2-RNAi-Lentivirus, and MMP-2 expression and invasive properties of the cells were evaluated. The experimental tumors in the nude mice were intratumorally injected with the same recombinant lentivirus. The inhibition of tumor growth was observed. The expression of MMP-2 protein in MMP-2 siRNA transfected Hep-2 cells was effectively suppressed. Both the viability and invasive ability of Hep-2 cells were significantly inhibited. The average weight and volume of tumor in MMP-2-RNAi-Lentivirus treated group were significantly lower than those in the control group (P < 0.01). The PCNA index was obviously lower in MMP-2 RNAi treated tumors (P < 0.01). In conclusion, MMP-2 silencing by recombinant lentivirus mediated RNA interference can inhibit invasion and growth of LSCC, and MMP-2 might be a potential target for gene therapy in LSCC.

Targeting a tumor-specific laminin domain critical for human carcinogenesis

Laminin-332 is critical for squamous cell carcinoma (SCC) tumorigenesis, but targeting it for cancer therapy has been unachievable due to key role of laminin-332 in promoting tissue integrity. Here, we show that a portion of laminin-332, termed G45, which is proteolytically removed and absent in normal tissues, is prominently expressed in most human SCC tumors and plays an important role in human SCC tumorigenesis. Primary human keratinocytes lacking G45 (DeltaG45) showed alterations of basal receptor organization, impaired matrix deposition, and increased migration. After SCC transformation, the absence of G45 domain in DeltaG45 cells was associated with deficient extracellular signal-regulated kinase and phosphotidylinositol 3-kinase (PI3K) pathway activation, impaired invasion, deficient metalloproteinase activity, and absent tumorgenicity in vivo. Expression of G45 or activated PI3K subunit in DeltaG45 cells reversed these abnormalities. G45 antibody treatment induced SCC tumor apoptosis, decreased SCC tumor proliferation, and markedly impaired human SCC tumorigenesis in vivo without affecting normal tissue adhesion. These results show a remarkable selectivity of expression and function for laminin-332 G45 in human SCC tumorigenesis and implicate it as a specific target for anticancer therapy.

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.

The slingshot family of phosphatases mediates Rac1 regulation of cofilin phosphorylation, laminin-332 organization, and motility behavior of keratinocytes

The motility of keratinocytes is an essential component of wound closure and the development of epidermal tumors. In vitro, the specific motile behavior of keratinocytes is dictated by the assembly of laminin-332 tracks, a process that is dependent upon alpha6beta4 integrin signaling to Rac1 and the actin-severing protein cofilin. Here we have analyzed how cofilin phosphorylation is regulated by phosphatases (slingshot (SSH) or chronophin (CIN)) downstream of signaling by alpha6beta4 integrin/Rac1 in human keratinocytes. Keratinocytes express all members of the SSH family (SSH1, SSH2, and SSH3) and CIN. However, expression of phosphatase-dead versions of all three SSH proteins, but not dominant inactive CIN, results in phosphorylation/inactivation of cofilin, changes in actin cytoskeleton organization, loss of cell polarity, and assembly of aberrant arrays of laminin-332 in human keratinocytes. SSH activity is regulated by 14-3-3 protein binding, and intriguingly, 14-3-3/alpha6beta4 integrin protein interaction is required for keratinocyte migration. We wondered whether 14-3-3 proteins function as regulators of Rac1-mediated keratinocyte migration patterns. In support of this hypothesis, inhibition of Rac1 results in an increase in 14-3-3 protein association with SSH. Thus, we propose a novel mechanism in which alpha6beta4 integrin signaling via Rac1, 14-3-3 proteins, and SSH family members regulates cofilin activation, cell polarity, and matrix assembly, leading to specific epidermal cell migration behavior.

Cytoplasmic expression of type VII collagen is related to prognosis in patients with esophageal squamous cell carcinoma

OBJECTIVE

Type VIIcollagen, the major component of anchoring fibrils, has been suggested to be involved with tumor cell invasion in a laminin-5-dependent manner in skin squamous cell carcinoma. However, the significance of type VII collagen expression in esophageal squamous cell carcinoma (ESCC) has been unknown to date. Therefore, we examined the expression of type VIIcollagen in ESCC, and confirmed the association between type VIIcollagen expression and clinicopathologic characteristics.

METHODS

We immunohistochemically examined the expression of type VII collagen and laminin-5 gamma2 chain in surgical specimens of primary tumors in 109 patients with ESCC.

RESULTS

Positive cytoplasmic expression of type VII collagen was detected in 35%. Significant correlation between the expression of type VII collagen and laminin-5 gamma2 chain expression was observed. In the type VII collagen-negative group, the 5-year survival rate was significantly better than in the positive group. Multivariate analysis indicated that the positive expression of type VII collagen was an independent prognostic factor.

CONCLUSIONS

The expression of type VII collagen was closely related to poor prognosis. Type VII collagen cytoplasmic expression could be a useful marker for evaluating the tumor cell properties, including prognosis, in patients with ESCC.

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.

Overexpression of laminin-5 gamma2 chain in clear cell carcinoma of the ovary

One of the characteristic microscopic features of ovarian clear cell carcinoma (CCC) is the densely hyaline basement membrane material expanding the stroma. The biological significance of this material, however, has remained unclear. Recent studies have shown that laminin-5 (LN-5), a major component of the epithelial basement membrane, plays a more active role in cell migration or tumor invasion. In the present study, 20 CCCs and 5 borderline clear cell tumors were examined for LN-5 expression immunohistochemically, using an antibody against LN-5 gamma2 chain. All of the 20 CCCs showed a focal or diffuse immunoreactivity with the LN-5 gamma2 chain in the tumor stroma; whereas, borderline clear cell tumors rarely showed a stromal immunoreactivity. Cytoplasmic accumulation of the LN-5 gamma2 chain was far less common than stromal accumulation, suggesting an accelerated secretion in CCC. In vitro, CCC cell lines showed a significant increase in cell migration over excessive LN-5, and the migration was blocked by an antibody against integrin alpha3. These results indicate that an interaction between CCC cells and extracellularly accumulated LN-5 is responsible for cell migration and the subsequent stromal invasion of CCC.

Prostate cancer metastasis: role of the host microenvironment in promoting epithelial to mesenchymal transition and increased bone and adrenal gland metastasis

BACKGROUND

The ARCaP cell line was established from the ascites fluid of a patient with metastatic prostate cancer. This study characterized the host microenvironmental role in cancer progression, epithelial to mesenchymal transition (EMT), and bone and adrenal metastasis in parental ARCaP and its derived cell subclones.

METHODS

Cytogenetic profiles, growth, migration, invasion, cellular interaction, drug sensitivities, and gene expression of ARCaP cell subclones were compared. In vivo gene expression, behavior, and metastasis of ARCaP subclones were analyzed by serial intracardiac injections into SCID mice.

RESULTS

ARCaP(E) cells, with cobblestone morphology, underwent EMT through cellular interaction with host bone and adrenal gland. Lineage-derived ARCaP(M) cells, with spindle-shape fibroblastic morphology, exhibited decreased cell adhesion and increased metastasis to bone and adrenal gland. Cytogenetic analyses of parental and ARCaP subclones confirmed their clonality.

CONCLUSIONS

ARCaP uniquely models the molecular basis of prostate cancer bone and adrenal metastases and epithelial to mesenchymal transition.

Regulation of proliferation and chondrogenic differentiation of human mesenchymal stem cells by laminin-5 (laminin-332)

Laminin-5 (laminin-332) is an important basement membrane protein that regulates cell attachment and motility. Recent studies have shown that laminin-5 is expressed in human mesenchymal stem cells (MSCs) in culture and that the laminin gamma2 chain is transiently expressed in chondrocytes during development. These studies suggest that laminin-5 may be involved in the regulation of chondrogenic differentiation of MSCs. In this study, we examined a possible role of laminin-5 in the proliferation and differentiation of human MSCs. When MSCs were incubated in the presence of a coated or soluble form of laminin-5 in a growth medium, they proliferated more rapidly than nontreated cells, keeping their differentiation potential. On the other hand, laminin-5 potently suppressed the chondrogenic differentiation of MSCs. These activities were mediated mainly by integrin alpha3beta1. However, laminin-5 had no effect on the osteogenic differentiation of MSCs. These results suggest that laminin-5 may contribute to the development of bone tissues by promoting the proliferation and by suppressing the chondrogenic differentiation of MSCs.

Experimental models and high-throughput diagnostics for tissue regeneration

During wound healing, cells recreate functional structures to regenerate the injured tissue. Understanding the healing process is essential for the development of new concepts and the design of novel biomimetic approaches for delivery of cells, genes and growth factors to accelerate tissue regeneration. To this end, realistic experimental models and high-throughput diagnostics are necessary to understand the molecular mechanisms of healing and reveal the genetic networks that determine tissue repair versus regeneration. Following a brief overview of the biology of wound healing, this review covers the in vitro and in vivo models that are employed at present to study the healing process. Discussion then covers the application of high-throughput genomic and proteomic technologies in epithelial development, living skin substitutes and wound healing. Finally, this review provides a perspective on novel technologies that should be developed to facilitate the understanding of wound healing complications and the design of therapeutics that target the underlying deficiencies.

Synthetic D-amino acid peptide inhibits tumor cell motility on laminin-5

Cell motility is partially dependent on interactions between the integrins and the extracellular matrix. Our previous studies have identified synthetic D-amino acid cell adhesion peptides using a combinatorial screening approach. In this study, we demonstrate that HYD1 (kikmviswkg) completely blocks random haptotactic migration and inhibits invasion of prostate carcinoma cells on laminin-5. This effect is adhesion independent and reversible. The inhibition of migration by HYD1 involves a dramatic remodeling of the actin cytoskeleton resulting in increased stress fiber formation and actin colocalization with cortactin at the cell membrane. HYD1 interacts with alpha6beta1 (not alpha6beta4) and alpha3beta1 integrins and surprisingly elevates laminin-5-dependent intracellular signals including focal adhesion kinase, mitogen-activated protein kinase kinase and extracellular signal-regulated kinase. HYD1 does not contain a previously characterized binding sequence for integrins. A scrambled derivative of HYD1, called HYDS (wiksmkivkg), does not interact with the alpha6 or alpha3 integrin subunits and is not biologically active. Taken together, these results indicate that HYD1 is a biologically active integrin-targeting peptide that reversibly inhibits tumor cell migration on laminin-5 and uncouples phosphotyrosine signaling from cytoskeletal-dependent migration.

Fibroblasts Accelerate Culturing of Mucosal Substitutes

Reconstruction of large mucosal defects of the floor of the mouth is typically performed with keratinizing skin. Drawbacks include donor site defects and hair bearing of the flaps. Cultured mucosal substitutes (CMSs) have been developed for clinical use to replace keratinizing skin. Acellular dermis is often used as a dermal carrier for autologous cells, because it reduces wound contraction and is easier for the surgeon to handle than, for example, collagen gels. A major problem of CMSs using acellular dermis is variation in epidermal quality. To improve the quality of the CMSs, human fibroblasts were incorporated into the acellular dermis and seeded with human keratinocytes. To study the role of the fibroblasts in epidermal morphology and basement membrane formation, CMSs were stained for differentiation markers beta1 integrin, cytokeratin 10, and involucrin after 1 and 2 weeks in culture. Basement membrane formation was analyzed using laminin 5 and collagen IV and VII staining; proliferation was analyzed using Ki-67 staining. The epidermises of fibroblast-containing CMSs matured faster into a well-organized epithelium than did those that did not contain CMSs. A 52.7% increase in basal cells, a 53.5% increase in mitosis index, and a 78.0% increase in keratinocyte cell layers were observed. Addition of fibroblasts reduced culturing time and enhanced proliferation, maturation, and quality of the epidermis.

Tight junction protein claudin-1 enhances the invasive activity of oral squamous cell carcinoma cells by promoting cleavage of laminin-5 gamma2 chain via matrix metalloproteinase (MMP)-2 and membrane-type MMP-1

Although adherent junctions have been extensively studied, the role of tight junctions in cancer cell invasion is not sufficiently explored. We investigated whether claudin-1, a component of tight junctions, regulated invasion activity in oral squamous cell carcinoma (OSC) cells. The expression of claudin-1, activity of matrix metalloproteinase (MMP)-2, and cleavage of laminin-5 gamma2 chains were assessed by Western blot analysis, immunohistochemistry, and zymography in OSC cell lines (OSC-4 and NOS-2, highly invasive; OSC-7, weakly invasive) and their xenografts in severe combined immunodeficient (SCID) mice. The influence of claudin-1 small interfering RNA (siRNA) on the invasion activity of the cell lines was also investigated. Compared with OSC-7, both OSC-4 and NOS-2 more strongly expressed claudin-1 and possessed high activities of MMP-2 and MMP-9. Tumors formed in the tongues of SCID mice xenografted with OSC-4, NOS-2, and OSC-7 immunohistochemically revealed strong, moderate, and weak expression of laminin-5 gamma2 chains, respectively, and laminin-5 gamma2 chains were secreted in the conditioned medium of the cancer cells in parallel with the in vivo results. Claudin-1 siRNA largely suppressed the invasion of OSC-4 and decreased the activation of MMP-2, the expression of membrane-type MMP-1 (MT1-MMP), and the cleavage of laminin-5 gamma2. In addition, not only antibodies against MT1-MMP and epidermal growth factor receptor (EGFR) but also MMP-2 and EGFR inhibitors strongly suppressed the invasion activity of OSC-4. These results suggest that claudin-1 up-regulates cancer cell invasion activity through activation of MT1-MMP and MMP-2, which results in enhanced cleavage of laminin-5 gamma2 chains.

Migratory marker expression in fibroblast foci of idiopathic pulmonary fibrosis

Background

Fibroblast foci (FF) are considered a relevant morphologic marker of idiopathic pulmonary fibrosis/usual interstitial pneumonia (IPF/UIP), and are recognised as sites where fibrotic responses are initiated and/or perpetuated in this severe disease. Despite their relevance, the cellular and molecular mechanisms responsible for the formation of FF and their role in tissue remodelling are poorly defined. In previous studies we have provided evidence of abnormal activation of the wnt-signaling-pathway in IPF/UIP that is centred on FF and the overlying epithelium. This important morphogenetic pathway is able to trigger epithelial-mesenchymal-transition (EMT), a mechanism involved in developmental and metastatic processes, which is also potentially involved in pulmonary fibrosis.

Methods

Since EMT is characterised by enhancement of migratory potential of cells, we investigated the molecular profile of FF in 30 biopsies of IPF/UIP and a variety of control samples, focussing on the immunohistochemical expression of three molecules involved in cell motility and invasiveness, namely laminin-5-γ2-chain, fascin, and heat-shock-protein-27.

Results

We provide evidence that in UIP these three molecules are abnormally expressed in discrete clusters of bronchiolar basal cells precisely localised in FF. These cellular clusters expressed laminin-5-γ2-chain and heat-shock-protein-27 at very high levels, forming characteristic three-layered lesions defined as "sandwich-foci" (SW-FF). Upon quantitative analysis SW-FF were present in 28/30 UIP samples, representing more than 50% of recognisable FF in 21/30, but were exceedingly rare in a wide variety of lung pathologies examined as controls. In UIP, SW-FF were often observed in areas of microscopic honeycombing, and were also found at the interface between normal lung tissue and areas of dense scarring.

Conclusion

These molecular abnormalities strongly suggest that SW-FF represent the leading edge of pulmonary remodelling, where abnormal migration and re-epithelialisation take place, and that abnormal proliferation and migration of bronchiolar basal cells have a major role in the remodelling process characterising IPF/UIP. Further investigations will assess their possible use as reliable markers for better defining the UIP-pattern in difficult cases.

Laminin-5 (laminin-332): Unique biological activity and role in tumor growth and invasion

The development and progression of tumor cells is controlled by their interactions with neighboring host cells and a variety of microenvironmental factors including extracellular matrix (ECM) molecules, growth factors and proteinases. Cell-adhesive ECM proteins are a prerequisite for growth and migration of many types of cells. Their interactions with integrins and other cell surface receptors induce intracellular signaling that regulates the actin cytoskeleton and gene expression. The basement membrane protein laminin-5 is a notable cell adhesion molecule, which promotes cellular adhesion and migration much more efficiently than other ECM proteins. There is accumulating evidence that laminin-5 is involved in tumor growth and progression. With special reference to laminin-5, this article reviews the regulatory mechanisms of cellular adhesion and migration by ECM molecules and their significance in tumor progression.

Laminin-5 suppresses chondrogenic differentiation of murine teratocarcinoma cell line ATDC5

Laminin-5 is an important basement membrane protein that regulates cell adhesion and motility. It was previously found that the gamma2 chain of laminin-5 is transiently expressed in embryonic cartilage. This suggests a possible role of laminin-5 in chondrogenesis. Here, we examined this possibility using the murine teratocarcinoma cell line ATDC5. ATDC5 cells transiently and weakly expressed laminin-5 when they were stimulated for differentiation. Exogenous laminin-5 in either insoluble or soluble form strongly inhibited the differentiation phenotypes, i.e. formation of cartilaginous cell aggregates and production of chondrogenic marker proteins through its integrin-binding domain LG3 in the alpha3 chain. Laminin-5 had no effect on cell growth. In addition, we found that the laminin-5 with the 105-kDa, processed gamma2 chain suppressed differentiation more strongly than one with the 150-kDa gamma2 chain. This indicated that the proteolytic processing of gamma2 chain regulated the activity of laminin-5. However, a gamma2 chain short arm fragment had no effect on the chondrogenesis, and it rather suppressed the differentiation at excessive concentrations. These results suggest that laminin-5 and its processing modulate chondrogenic differentiation during development.

Regulation of cell adhesion and type VII collagen binding by the beta3 chain short arm of laminin-5: effect of its proteolytic cleavage

The basement membrane protein laminin-5 (Lm5), a heterotrimer of alpha3 (or alpha3A), beta3, and gamma2 chains, regulates cellular adhesion and motility. Here we examined the proteolysis and biological function of the laminin beta3 chain. First, we found that the beta3 chain of Lm5 is cleaved at its N-terminal, short arm by an endogenous proteinase(s) in normal human keratinocytes and some other cell lines. To examine the effect of beta3 chain cleavage, we expressed a wild-type Lm5 and two Lm5 mutants with partially deleted beta3 chains in HEK293 cells. Experiments with the purified Lm5 forms demonstrated that the deletion of the beta3 short arm or its N-terminal domain LN decreases the cell adhesion activity of Lm5, but does not significantly affect the motility activity. A recombinant beta3 short arm protein enhanced integrin-mediated cell adhesion to Lm5 by binding to an unidentified cell receptor. It was also found that the laminin EGF-like domain of the beta3 short arm is a binding site for type VII collagen. These results suggest that the beta3 short arm is involved not only in the matrix assembly of Lm5, but also in its cell adhesion activity. The proteolytic cleavage of the beta3 chain may modulate these functions of Lm5 in vivo.

Regulation of biological activity and matrix assembly of laminin-5 by COOH-terminal, LG4-5 domain of alpha3 chain

The basement membrane protein laminin-5 (LN5; alpha3beta3gamma2) undergoes specific proteolytic processing of the 190-kDa alpha3 chain to the 160-kDa form after the secretion, releasing its COOH-terminal, LG4-5 domain. To clarify the biological significance of this processing, we tried to express a recombinant precursor LN5 with a 190-kDa alpha3 chain (pre-LN5), in which the cleavage sequence Gln-Asp was changed to Ala-Ala by point mutation. When the wild-type and mutated LN5 heterotrimers were expressed in HEK293 cells, the wild-type alpha3 chain was completely cleaved, whereas the mutated alpha3 chain was partially cleaved at the same cleavage site (Ala-Ala). pre-LN5 was preferentially deposited on the extracellular matrix, but this deposition was effectively blocked by exogenous heparin. This suggests that interaction between the LG4-5 domain and heparan sulfate proteoglycans on the cell surface and/or extracellular matrix is important in the matrix assembly of LN5. Next, we purified both pre-LN5 and the mature LN5 with the processed, 160-kDa alpha3 chain (mat-LN5) from the conditioned medium of the HEK293 cells and compared their biological activities. mat-LN5 showed higher activities to promote cell adhesion, cell scattering, cell migration, and neurite outgrowth than pre-LN5. These results indicate that the proteolytic removal of LG4-5 from the 190-kDa alpha3 chain converts the precursor LN5 from a less active form to a fully active form. Furthermore, the released LG4-5 fragment stimulated the neurite outgrowth in the presence of mat-LN5, suggesting that LG4-5 synergistically enhances integrin signaling as it is released from the precursor LN5.