title: Alteration in composition of keratin intermediate filaments in a model of breast cancer progression and the potential to reverse hallmarks of metastasis.
abstract: BACKGROUND
  In breast cancer the development of metastasis is a major turning point in the treatment and outcome of the disease. Throughout tumour development, and especially in the development of metastasis, epithelial mesenchymal transition takes place. During this transformation into a mesenchymal phenotype, the tumour cells undergo a series of structural changes. The loss of structural integrity and adoption of mesenchymal filaments enables cells to detach from the epithelial cell layer and metastasise. Keratins form the intermediate filaments of the cytoskeleton and provide scaffold structures within cells. During cancer progression the intermediate filaments are reorganised, and dramatic changes are seen in their protein components. Keratins K8, K18, K19 and vimentin are intermediate filament proteins with altered expression profiles during tumour development.
  
  
  METHODS
  We have used in vivo and in vitro models to analyse changes in intermediate filament proteins. Antibody-based methods were used to study K8 levels and proteomic analysis to profile the protein content of metastatic breast cancer cell variants.
  
  
  RESULTS
  K8 expression declines as human breast tumours progress into an invasive phenotype. Analysis of IF proteins indicated altered expression profiles of K8, K18, K19 and vimentin, with K8, K18, K19 expressed in high levels in the T47D and MCF-7 cell lines, whereas the highly metastatic cell lines expressed lower levels of K8 and K18 and no detectable K19. Vimentin showed reverse expression profile with T47D and MCF-7 cells having no detectable vimentin expression whereas the highly metastatic MDA-MB-231 and MDA-MB-436 showed high levels. Analysis of acetylation status using specific antibodies suggested acetylation occurred within the central coiled domain in the MCF-7 and T47D cells. Inhibition of tumour growth by tissue factor (TF) shRNA resulted in a dramatic re-elevation of expression of K8 in xenographs of the highly metastatic MDA-MB-436 line.
  
  
  CONCLUSIONS
  Intermediate filament expression alters during epithelial mesenchymal transition. Identified post translational modifications may play a role in alterations seen in the organisation, solubility and stability of these filaments. Epithelial mesenchymal transition can be reversed and an epithelial phenotype re-established.
authors: Academic Unit of Surgical Oncology, Department of Oncology, University of Sheffield, The Medical School, Sheffield, UK.
authors: Mary Anne
authors: MA
authors: Mackinder
authors: Caroline Akrill
authors: CA
authors: Evans
authors: Joanna
authors: J
authors: Chowdry
authors: Carolyn Ann
authors: CA
authors: Staton
authors: Bernard Michael
authors: BM
authors: Corfe
mesh_terms: D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D045744:Cell Line, Tumor; D018450:Disease Progression; D058750:Epithelial-Mesenchymal Transition; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007382:Intermediate Filaments / Q000235:genetics / Q000378:metabolism*; D007633:Keratins / Q000235:genetics / Q000378:metabolism*; D009362:Neoplasm Metastasis
chemical_list: D007633:Keratins