title: Epithelial-mesenchymal transition downregulates laminin alpha5 chain and upregulates laminin alpha4 chain in oral squamous carcinoma cells.
abstract: Basement membranes maintain the epithelial phenotype and prevent invasion and metastasis. We hypothesized that expression of basement membrane laminins might be regulated by epithelial-mesenchymal transition (EMT), hallmark of cancer progression. As EMT is mediated by transcription factor Snail, we used oral squamous carcinoma cells obtained from a primary tumor (43A), from its EMT-experienced recurrence (43B) and Snail-transfected 43A cells (43A-SNA) displaying full EMT, as a model to study laminins and their receptors. Northern blotting, immunofluorescence, and immunoprecipitation showed a gradual loss of laminin-511 and its receptor Lutheran from 43A to 43B and 43A-SNA cells. In contrast, neoexpression of laminin alpha4 mRNA was found congruent with synthesis of laminin-411. Chromatin immunoprecipitation disclosed direct binding of Snail to regions upstream of laminin alpha5 and alpha4 genes. Immunofluorescence and immunoprecipitation showed a switch from hemidesmosomal integrin alpha(6)beta(4) to alpha(6)beta(1) and neoexpression of alpha(1)beta(1) in 43A-SNA cells, and upregulation of integrin-linked kinase in both 43B and 43A-SNA cells. The cells adhered potently to laminin-511 and fibronectin, whereas adhesion to laminin-411 was minimal. In contrast, laminin-411 inhibited cell adhesion to other extracellular matrix proteins. In conclusion, EMT induces a switch from laminin-511 to laminin-411 expression, which may be directly controlled by Snail. Concomitant changes take place in laminin- and collagen-binding receptors. Laminin-411 reduces adhesion to laminin-511 and fibronectin, suggesting that tumor cells could utilize laminin-411 in their invasive behavior.
authors.affiliation: Institute of Biomedicine/Anatomy, University of Helsinki, PO Box 63 (Haartmaninkatu 8), 00014 Helsinki, Finland. minna.k.takkunen@helsinki.fi
authors.forename: Minna
authors.initials: M
authors.lastname: Takkunen
authors.forename: Mari
authors.initials: M
authors.lastname: Ainola
authors.forename: Noora
authors.initials: N
authors.lastname: Vainionpää
authors.forename: Reidar
authors.initials: R
authors.lastname: Grenman
authors.forename: Manuel
authors.initials: M
authors.lastname: Patarroyo
authors.forename: Antonio
authors.initials: A
authors.lastname: García de Herreros
authors.forename: Yrjö T
authors.initials: YT
authors.lastname: Konttinen
authors.forename: Ismo
authors.initials: I
authors.lastname: Virtanen
mesh_terms: D000368:Aged; D002294:Carcinoma, Squamous Cell / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D002454:Cell Differentiation; D045744:Cell Line, Tumor; D015536:Down-Regulation; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007797:Laminin / Q000235:genetics / Q000378:metabolism*; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000378:metabolism*; D009062:Mouth Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D009361:Neoplasm Invasiveness / Q000473:pathology; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D021122:Protein Subunits / Q000378:metabolism; D017474:Receptors, Laminin / Q000378:metabolism; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors / Q000378:metabolism; D015854:Up-Regulation
chemical_list: C501369:LAMA4 protein, human; D007797:Laminin; D021122:Protein Subunits; D017474:Receptors, Laminin; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors; C097043:laminin alpha5