The SFL activity secreted by metastatic carcinoma cells is related to laminin 5 and mediates cell scattering in an integrin-independent manner

Effect of laminin 332 on motility and invasion in bladder cancer

We examined the correlation between laminin 332 and malignancy in bladder cancer patients, and, using a strain of invasive bladder cancer cells, determined whether laminin 332 causes bladder cancer motility and invasion. To investigate the correlation between laminin 332 g2 distribution and patient outcome, we performed a semiquantitative immunohistochemical analysis of 35 paraffin-embedded samples using the antibody D4B5, which is specific for the laminin 5 γ2 chain. To evaluate the role of laminin 332 in NBT-II cell motility and invasion, we used a scratch assay and the Boyden chamber chemoinvasion system. Tumor stage and grade were significantly correlated with a loss of laminin 332 γ2 chain from the basement membrane (p = 0.001) and its retention in the cytoplasm (p = 0.001) (Kruskal-Wallis test). Kaplan-Meier survival curves revealed an association between the risk of progression and cytoplasmic retention of the laminin 332 γ2 chain. In addition, an in vitro scratch assay showed an increase in the migration of cells treated with laminin 332 from their cluster. The Boyden chamber assay showed that laminin 332 potentiated NBT-II cell invasion. Immunohistochemistry results showed that bladder cancer patients with a higher malignancy expressed more laminin 332. The in vitro scratch and invasion assay showed that laminin 332 stimulated the motility and invasion of bladder cancer cells. The invasion assay explains the correlation between laminin 332 expression and bladder cancer malignancy.

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.

Laminin-5 beta3A expression in LNCaP human prostate carcinoma cells increases cell migration and tumorigenicity

Interactions between extracellular matrix proteins and prostate carcinoma cells change dramatically during prostate tumor progression. We have concentrated on two key modifications that occur in the hemidesmosome in prostate carcinoma: loss of laminin-5 protein expression and altered basal cell polarity of the alpha6beta4 integrin. We previously demonstrated two cell line-specific isoforms (beta3A and beta3B) of the LAMB3 message. Cells expressing only the beta3B isoform did not translate the beta3 protein and were unable to assemble the laminin-5 trimer. One such cell line, LNCaP, was selected to determine whether restoration of the laminin-5 beta3A isoform would cause expression of a functional laminin-5 beta3 chain, assembly and secretion of the laminin-5 trimer, and reversion to a non-neoplastic phenotype. Laminin-5 beta3A cDNA was cloned and stably transfected into LNCaP cells. We observed the restoration of the beta3 protein, but a laminin-5 trimer was not secreted. Moreover, increased cell migration was demonstrated, and tumorigenicity was increased in SCID mice. A microarray analysis, performed between transfected and nontransfected LNCaP cells, showed most changing genes to be associated with signal transduction. The beta3 chain of laminin-5 may thus play an important role in signal transduction, which may enhance cell motility and tumorigenesis.

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

One of the basement membrane (BM) proteins, laminin-5 (LN5), is known to support efficient cell adhesion and migration through interaction with integrins on the basal plasma membrane. Here, we show that a soluble form of LN5 induced migration of human epithelial cells and carcinoma cells by interacting with integrins on the apical cell surface. Although both LN5 and laminin-10/11 (LN10/11) promoted cell migration when coated onto a plastic surface as insoluble substrata, only LN5 stimulated cell migration in its soluble form on other substrata such as fibronectin (FN), vitronectin (VN) and collagen. Soluble LN5 interacted with integrins alpha3beta1 and alpha6beta1 on the apical cell surface and stimulated cell migration, while the cell morphology was largely dependent on the underlying substratum. Thus, integrin signals from the apical surface and the basal surface synergistically regulated cytoskeletal organization and cell motility. Soluble and insoluble LN5 induced cell motility by activating signal pathways via protein kinase C (PKC), phosphoinositide 3-OH kinase (PI3-K) and MAP kinase. The PKC dependency was more prominent for soluble LN5 than insoluble LN5, and was absent in the stimulation by insoluble LN10/11. In vitro scratch assays with keratinocytes, self-produced soluble LN5 bound to the apical cell surface of migrating cells at the scratched edges, suggesting that soluble LN5 may contribute to cell migration in pathological conditions such as wound healing and tumor invasion.

Beta4 integrin and laminin 5 are aberrantly expressed in polycystic kidney disease: role in increased cell adhesion and migration

Extracellular matrix alterations have been suggested to be part of the early events occurring in Autosomal Dominant Polycystic Kidney Disease (ADPKD), a disease characterized by formation of renal cysts and progressive renal failure. Here we report that cDNA array analysis identified beta(4) integrin aberrant expression in ADPKD cells. Furthermore, laminin 5 (Ln-5), the main alpha(6)beta(4) integrin ligand, was also found to be abnormally expressed in ADPKD. Studies performed with ADPKD cyst-lining epithelial cells (CC) by comparison with normal tubular cells indicate that integrin alpha(6)beta(4)-Ln-5 interactions are involved in cellular events of potential importance for cystogenesis: 1) laminin 5 is a preferential adhesion substrate for CC, mainly through alpha(6)beta(4) interaction, 2) CC increased haptotactic and chemotactic motility depends on the presence of Ln-5 and requires integrin alpha(3)beta(1) cooperation, and 3) CC haptotactic or chemotactic migration is specifically increased by mAb-mediated beta(4) integrin ligation, through an alpha(3)beta(1) integrin-dependent and independent pathway, respectively. These results highlight the role of Ln-5 and alpha(6)beta(4) integrin in adhesive and motility properties of cyst-lining epithelial cells, and further suggest that integrins and extracellular matrix modifications may be of general relevance to kidney epithelial cell cyst formation.

The association of the tetraspanin D6.1A with the alpha6beta4 integrin supports cell motility and liver metastasis formation

The metastatic subline of a rat pancreatic adenocarcinoma differs from the non-metastasizing subline by overexpression of 5 membrane molecules: CD44 variant isoforms, EpCAM, the tetraspanin D6.1A, an uPAR-related molecule and, as described here, the alpha6beta4 integrin. An antibody-defined molecule was identified by mass spectrometry and cloning as alpha6beta4 integrin. Transfection-induced expression of alpha6beta4 in the non-metastasizing subline did not support migration on laminin 5 or tumor progression. However, when the non-metastasizing subline was doubly transfected to express alpha6beta4 and the D6.1A tetraspanin, intraperitoneally injected tumor cells frequently formed liver metastasis. For the following reasons we assume that metastasis formation is supported by an interaction between alpha6beta4 and D6.1A. (i) The 2 molecules can associate and co-localize. (ii) Co-localization is strengthened by PKC stimulation. (iii) PKC stimulation, which induces a migratory phenotype, leads to a redistribution of alpha6beta4/D6.1A complexes. In resting cells, the molecules co-localize at the trail of the cell; during PKC stimulation they become transiently internalized and are (re-)expressed in the leading lamella. Thus, in the appropriate milieu, i.e. intraperitoneally, alpha6beta4 changes from an adhesion-supporting towards a migration-supporting molecule by its association with a tetraspanin. The findings provide a convincing experimental explanation for the repeatedly described involvement of alpha6beta4 in tumor progression.

Distribution of laminin 5, integrin receptors, and branching morphogenesis during human fetal lung development

The role of the epithelial adhesion ligand laminin 5 (LN5) in lung development has been poorly investigated. To determine its potential involvement in lung organogenesis, we used immunofluorescence microscopy to investigate the distribution of LN5 and its integrin (Int) receptors alpha2beta1, alpha3beta1, alpha6beta1, and alpha6beta4 during human fetal airway branching morphogenesis and respiratory epithelium differentiation. At the pseudoglandular and canalicular stages of airway development, LN5 and its constituent chains were localized in the basement membrane (BM) of the proximal respiratory tubules and in the cytoplasm of the epithelial cells forming the growing epithelial buds, which expressed Int alpha2beta1, alpha3beta1, and, transiently, alpha6beta1. At the alveolar and adult stages, LN5 and its constituent chains were localized both in the BM of evolving and differentiated bronchioles and in the alveolar parenchyma. The bronchiolar epithelium markedly expressed Int alpha2beta1 and alpha3beta1, whereas the alveolar parenchyma strongly expressed Int alpha2beta1, alpha3beta1, and alpha6beta1. Throughout fetal development and in the adult, LN5 and its constituent chains were detected both in the tracheal BM, regardless of the degree of epithelial differentiation, and in the cytoplasm of the cells at the invading front of the growing glandular ducts. Ultrastructural studies showed that nucleation of the hemidesmosomes (HDs) correlated with the differentiation of the tracheal epithelium. These results suggest that LN5 may play multiple roles during branching morphogenesis, by modulating proliferation and/or migration of the epithelial cells in the respiratory buds and by establishing branch points, through interaction initially with Int alpha6beta1 and later with Int alpha2beta1 and alpha3beta1. We also propose that LN5 may regulate the differentiation of the tracheal epithelium by means of Int-beta4, which governs HD nucleation.

Host microenvironment in breast cancer development: epithelial-mesenchymal transition in breast cancer development

The epithelial-mesenchymal transition (EMT) is a developmental mechanism of crucial importance in establishing the body plan in many multicellular organisms. Several transduction pathways controlling the various steps of the morphological transition have been identified by molecular analyses of this process in cell lines and in vivo. The newly formed mesenchymal cells can exhibit locomotory and invasive phenotypes, suggesting that EMTs contribute to the progression of carcinoma. Diverse evidence indicates that EMT subprograms are involved in the appearance of different breast carcinoma types. Several normal and malignant breast cell lines are currently being analyzed to define key steps in EMT and to identify candidate genes. DNA profiling technology is also being applied to uncover pathways that lead to a metastatic phenotype.

Contribution of MT1-MMP and of human laminin-5 gamma2 chain degradation to mammary epithelial cell migration

Membrane-type matrix metalloproteinase 1 (MT1-MMP) is a membrane-anchored matrix metalloproteinase (MMP) that is frequently associated with processes involving tissue remodelling and cell migration. We have examined MT1-MMP expression and subcellular distribution as a function of MCF10A mammary epithelial cell migration using an in vitro outgrowth migration assay. Stronger expression of MT1-MMP was observed at the mRNA and at the protein level in cells at the periphery of the outgrowth. As shown by videomicroscopy, these cells were involved in an orientated cell migration, in contrast to stationary cells distant from the periphery. Furthermore, MT1-MMP was mainly distributed in lamellipodia of migratory cells, as well as at their basal surface in contact with the substrate. Laminin-5 (Ln-5), a recently described substrate for MT1-MMP, was deposited preferentially in the matrix by migratory cells. Fragments of the gamma2 subunit of Ln-5 were also identified in migratory cultures of MCF10A cells, attesting to its proteolytic degradation. These fragments corresponded in size to those we observed after incubation of purified human Ln-5 with the recombinant catalytic domain of human MT1-MMP. We also show that anti-Ln5 blocking antibodies, MMP inhibitors (BB94 and TIMP-2) and MT1-MMP antisense oligonucleotides significantly decreased MCF10A cell migration. Taken together, these observations demonstrate that MT1-MMP is spatially and temporally regulated during MCF10A cell migration, and suggest that MT1-MMP-mediated pericellular proteolysis of Ln-5 gamma2 chain could contribute to this process.

Hydrophobic Laminin-Related Peptides: Synthesis and Surface Properties

The synthesis of hydrophobic peptide derivatives related to the laminin sequence [YIGSR(NH(2))] is described. Hydrophobicity is achieved by the attachment of decanoic, myristic, or stearic acids to the amino terminal end of the peptide. Moreover, a cholesterol residue was also introduced as succinimidoyl-cholesteryl moiety at the same position. These peptidic compounds are designed to be inserted into lipid bilayers to prepare, what can be considered as, immunoliposomes to target these vesicles to tumor cells. Physicochemical aspects related to their surface activity, insertion into lipid layers, spreadibility, formation of aggregates, and haemolytic activity have been studied as a previous step in the selection of the most convenient derivative. The results obtained indicate that these peptide derivatives show a high tendency to form aggregates in aqueous media, this fact reducing their interaction with lipid mono- and bilayers. The most suitable derivatives for interacting with liposomes are myristoyl and decanoyl. Copyright 2001 Academic Press.

Laminin-5-mediated gene expression in human prostate carcinoma cells

Interactions between extracellular matrix (ECM) proteins and prostate carcinoma cells provide a dynamic model of prostate tumor progression. Previous work in our laboratory showed that laminin-5, an important member of a family of ECM glycoproteins expressed in the basal lamina, is lost in prostate carcinoma. Moreover, we showed that the receptor for laminin-5, the alpha6beta4 integrin, is altered in prostate tumors. However, the genes that laminin-5 potentially regulates and the significance of its loss of expression in prostate cancer are not known. We selected cDNA microarray as a comprehensive and systematic method for surveying and examining gene expression induced by laminin-5. To establish a definitive role for laminin-5 in prostate tumor progression and understand the significance of its loss of expression, we used a cDNA microarray containing 5289 human genes to detect perturbations of gene expression when DU145 prostate carcinoma cells interacted with purified laminin-5 after 0.5, 6, and 24 h. Triplicate experiments showed modulations of four, 61, and 14 genes at 0.5, 6, and 24 h, respectively. Genes associated with signal transduction, cell adhesion, the cell cycle, and cell structure were identified and validated by northern blot analysis. Protein expression was further assessed by immunohistochemistry. Mol. Carcinog. 30:119-129, 2001.