title: EZH2 knockdown suppresses the growth and invasion of human inflammatory breast cancer cells.
abstract: BACKGROUND
  Inflammatory breast cancer (IBC) is the most metastatic variant of breast cancer with the poorest survival in all types of breast cancer patients and presently therapeutic targets for IBC are very limited. Enhancer of zeste homolog 2 (EZH2) is frequently expressed in human IBC and its expression positively correlates with worse clinical outcome. However, the molecular basis for EZH2 promoting IBC has not been explored. Here, we investigated the functional role of EZH2 in IBC cells by examining the effects of its knockdown on the formation of tumor spheroids and invasion of these cells in vitro and in vivo in an orthotopic xenograft model.
  
  
  METHODS
  SUM149 and a new IBC cell line-FC-IBC-02 derived from pleural effusion fluid of an IBC patient were used in this study. Specific knockdown of EZH2 was performed using short hairpin RNA (shRNA) specific to the human EZH2 gene. Cell growth and the formation of tumor spheroids were examined in vitro. The effects of EZH2 knockdown on IBC cell migration and invasion were examined by a Boyden chamber assay. For the in vivo tumor growth studies, IBC cells were orthotopically transplanted into the mammary fat pads of immunodeficient mice.
  
  
  RESULTS
  The results showed that EZH2 is expressed at higher levels in human IBC cell lines compared with normal human mammary epithelial cells, and the knockdown of EZH2 expression significantly suppressed cell growth and tumor spheroid formation of human IBC cells in vitro. In addition, EZH2 knockdown inhibited the migration and invasion of IBC cells. Significantly, EZH2 knockdown suppressed the angiogenesis and tumor growth of IBC cells in vivo.
  
  
  CONCLUSIONS
  Our results provide direct evidence that EZH2 is critical for the formation of tumor spheroids and invasion of human IBC cells and could be a potential target for developing novel therapeutic strategies for human IBC.
authors.forename: Zhaomei
authors.initials: Z
authors.lastname: Mu
authors.forename: Hua
authors.initials: H
authors.lastname: Li
authors.forename: Sandra V
authors.initials: SV
authors.lastname: Fernandez
authors.forename: Katherine R
authors.initials: KR
authors.lastname: Alpaugh
authors.forename: Rugang
authors.initials: R
authors.lastname: Zhang
authors.forename: Massimo
authors.initials: M
authors.lastname: Cristofanilli
mesh_terms: D000818:Animals; D048708:Cell Growth Processes / Q000502:physiology; D000071221:Enhancer of Zeste Homolog 2 Protein; D005260:Female; D055785:Gene Knockdown Techniques; D006801:Humans; D058922:Inflammatory Breast Neoplasms / Q000235:genetics* / Q000473:pathology; D016180:Lentivirus Infections / Q000235:genetics / Q000378:metabolism; D051379:Mice; D016513:Mice, SCID; D014411:Neoplastic Stem Cells / Q000378:metabolism; D063151:Polycomb Repressive Complex 2 / Q000235:genetics / Q000378:metabolism*; D018874:Spheroids, Cellular; D016019:Survival Analysis
chemical_list: C498409:EZH2 protein, human; D000071221:Enhancer of Zeste Homolog 2 Protein; D063151:Polycomb Repressive Complex 2