title: Identification of integrins alpha6 and beta7 as c-Jun- and transformation-relevant genes in highly invasive fibrosarcoma cells.
abstract: Understanding the mechanisms of tumor cell invasion is essential for our attempts to prevent cancer deaths. We screened by DNAmicroarrays the c-Jun- and transformation-related gene expression changes in S-adenosylmethionine decarboxylase (AdoMetDC)-overexpressing mouse fibroblasts that are highly invasive in vivo, and their derivatives expressing a tetracycline-inducible dominant-negative mutant of c-Jun (TAM67) or c-Jun shRNA. Among the small set of target genes detected were integrins alpha6 and beta7, cathepsin L and thymosin beta4, all upregulated in the AdoMetDC-transformed cells and downregulated upon reversal of transformation by TAM67 or c-Jun shRNA. The upregulation of integrin alpha6 subunit, pairing with integrin beta1, endowed the transformed cells with the capability to attach to basement membrane laminin and to spread. Further, inhibition of integrin alpha6 or beta1 function with neutralizing antibodies blocked the invasiveness of AdoMetDC-transformants and human HT-1080 fibrosarcoma cells in three-dimensional Matrigel. Moreover, immunohistochemical analyses showed strong integrin alpha6 staining in high-grade human fibrosarcomas. Our data show that c-Jun can regulate all three key steps of invasion: cell adhesion (integrin alpha6), basement membrane/extracellular matrix degradation (cathepsin L) and cell migration (thymosin beta4). In addition, this is the first study to associate integrin beta7, known as a leukocyte-specific integrin binding to endothelial/epithelial cell adhesion molecules, with the transformed phenotype in cells of nonleukocyte origin. As tumor cell invasion is a prerequisite for metastasis, the observed critical role of integrin alpha6beta1 in fibrosarcoma cell invasion/spreading allures testing antagonists to integrin alpha6beta1, alone or combined with inhibitors of cathepsin L and thymosin beta4, as chemotherapeutic agents.
authors.affiliation: Haartman Institute, Department of Pathology, University of Helsinki and Helsinki University Central Hospital, Finland.
authors.forename: Mari
authors.initials: M
authors.lastname: Kielosto
authors.forename: Pirjo
authors.initials: P
authors.lastname: Nummela
authors.forename: Kristiina
authors.initials: K
authors.lastname: Järvinen
authors.forename: Miao
authors.initials: M
authors.lastname: Yin
authors.forename: Erkki
authors.initials: E
authors.lastname: Hölttä
mesh_terms: D012437:Adenosylmethionine Decarboxylase / Q000378:metabolism; D000818:Animals; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism; D015153:Blotting, Western; D002465:Cell Movement; D002471:Cell Transformation, Neoplastic / Q000235:genetics* / Q000378:metabolism; D003094:Collagen / Q000378:metabolism; D004338:Drug Combinations; D005347:Fibroblasts / Q000378:metabolism; D005354:Fibrosarcoma / Q000201:enzymology / Q000235:genetics* / Q000473:pathology; D005455:Fluorescent Antibody Technique; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000502:physiology*; D006801:Humans; D007124:Immunoenzyme Techniques; D047468:Immunoprecipitation; D039121:Integrin alpha6beta1 / Q000502:physiology*; D039641:Integrin beta Chains / Q000502:physiology*; D048031:JNK Mitogen-Activated Protein Kinases / Q000235:genetics*; D007797:Laminin / Q000378:metabolism; D051379:Mice; D041681:NIH 3T3 Cells; D009361:Neoplasm Invasiveness; D020411:Oligonucleotide Array Sequence Analysis; D011509:Proteoglycans / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012436:S-Adenosylmethionine / Q000378:metabolism
chemical_list: D014408:Biomarkers, Tumor; D004338:Drug Combinations; D039121:Integrin alpha6beta1; D039641:Integrin beta Chains; D007797:Laminin; D011509:Proteoglycans; D012333:RNA, Messenger; D034741:RNA, Small Interfering; C091368:integrin beta7; C059485:matrigel; D012436:S-Adenosylmethionine; D003094:Collagen; D048031:JNK Mitogen-Activated Protein Kinases; D012437:Adenosylmethionine Decarboxylase