title: Extracellular Hsp90 and TGFβ regulate adhesion, migration and anchorage independent growth in a paired colon cancer cell line model.
abstract: Tumour metastasis remains the major cause of death in cancer patients and, to date, the mechanism and signalling pathways governing this process are not completely understood. The TGF-β pathway is the most commonly mutated pathway in cancer, however its role in cancer progression is controversial as it can function as both a promoter and a suppressor of metastasis. Although previous studies have suggested a role for the molecular chaperone Hsp90 in regulating the TGF-β pathway, the level at which this occurs as well as the consequences in terms of colon cancer metastasis are unknown.
  
  
  
  The paired SW480 and SW620 colon cancer cell lines, derived from a primary tumour and its lymph node metastasis, respectively, were used as an in vitro model to study key cellular processes required for metastasis. The status of the TGF-β pathway was examined in these cells using ELISA, flow cytometry, western blot analysis and confocal microscopy. Furthermore, the effect of addition or inhibition of the TGF-β pathway and Hsp90 on adhesion, migration and anchorage-independent growth, was determined in the cell lines.
  
  
  
  When comparing the canonical TGF-β1 pathway in the genetically paired cell lines our data suggests that this pathway may be constitutively active in the SW620 metastasis-derived cell line and not the SW480 primary tumour-derived line. In addition, we report that, when present in combination, TGF-β1 and Hsp90β stimulate anchorage-independent growth, reduce adhesion and stimulate migration. This effect is potentiated by inhibition of the TGF-β1 receptor and occurs via an alternate TGF-β1 pathway, mediated by αvβ6 integrin. Interestingly, in the SW620 cells, activation of this alternate TGF-β1 signalling machinery does not appear to require inhibition of the canonical TGF-β1 receptor, which would allow them to respond more effectively to the pro-metastasis stimulus of a combination of Hsp90β and TGF-β1 and this could account for the increased migratory capacity of these cells.
  
  
  
  In this study we report an apparent synergy between TGF-β1 and Hsp90β in stimulating migratory behaviour of colon cancer cells when signalling occurs via αvβ6 integrin as opposed to the canonical TGF-β1 pathway.
authors.affiliation: The Biomedical Biotechnology Research Unit, Department of Biochemistry and Microbiology, Rhodes University, Grahamstown, 6139, South Africa.
authors.forename: Jo-Anne
authors.initials: JA
authors.lastname: de la Mare
authors.affiliation: The Biomedical Biotechnology Research Unit, Department of Biochemistry and Microbiology, Rhodes University, Grahamstown, 6139, South Africa.
authors.forename: Tamarin
authors.initials: T
authors.lastname: Jurgens
authors.affiliation: The Biomedical Biotechnology Research Unit, Department of Biochemistry and Microbiology, Rhodes University, Grahamstown, 6139, South Africa. a.edkins@ru.ac.za.
authors.forename: Adrienne L
authors.initials: AL
authors.lastname: Edkins
mesh_terms: D002448:Cell Adhesion / Q000235:genetics; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000235:genetics; D049109:Cell Proliferation / Q000235:genetics*; D003110:Colonic Neoplasms / Q000235:genetics* / Q000473:pathology; D015972:Gene Expression Regulation, Neoplastic; D018841:HSP90 Heat-Shock Proteins / Q000235:genetics*; D006801:Humans; D039564:Integrin alphaV / Q000235:genetics; D009362:Neoplasm Metastasis; D015398:Signal Transduction; D053773:Transforming Growth Factor beta1 / Q000235:genetics*
chemical_list: D018841:HSP90 Heat-Shock Proteins; C493165:HSP90AB1 protein, human; D039564:Integrin alphaV; D053773:Transforming Growth Factor beta1
keywords: Anchorage-independent growth; Colon cancer; Hsp90; Migration; TGF-β pathway