title: Quantitative proteomic analysis of sphere-forming stem-like oral cancer cells.
abstract: BACKGROUND
  The purpose of this study is to identify target proteins that may play important functional roles in oral cancer stem-like cells (CSCs) using mass spectrometry-based quantitative proteomics.
  
  
  METHODS
  Sphere-formation assays were performed on highly invasive UM1 and lowly invasive UM2 oral cancer cell lines, which were derived from the same tongue squamous cell carcinoma, to enrich CSCs. Quantitative proteomic analysis of CSC-like and non-CSC UM1 cells was carried out using tandem mass tagging and two-dimensional liquid chromatography with Orbitrap mass spectrometry.
  
  
  RESULTS
  CSC-like cancer cells were found to be present in the highly invasive UM1 cell line but absent in the lowly invasive UM2 cell line. Stem cell markers SOX2, OCT4, SOX9 and CD44 were up-regulated, whereas HIF-1 alpha and PGK-1 were down-regulated in CSC-like UM1 cells versus non-CSC UM1 cells. Quantitative proteomic analysis indicated that many proteins in cell cycle, metabolism, G protein signal transduction, translational elongation, development, and RNA splicing pathways were differentially expressed between the two cell phenotypes. Both CREB-1-binding protein (CBP) and phosphorylated CREB-1 were found to be significantly over-expressed in CSC-like UM1 cells.
  
  
  CONCLUSIONS
  CSC-like cells can be enriched from the highly invasive UM1 oral cancer cell line but not from the lowly invasive UM2 oral cancer cell line. There are significant proteomic alterations between CSC-like and non-CSC UM1 cells. In particular, CBP and phosphorylated CREB-1 were significantly up-regulated in CSC-like UM1 cells versus non-CSC UM1 cells, suggesting that the CREB pathway is activated in the CSC-like cells.
authors.forename: Kaori
authors.initials: K
authors.lastname: Misuno
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Liu
authors.forename: Sizhe
authors.initials: S
authors.lastname: Feng
authors.forename: Shen
authors.initials: S
authors.lastname: Hu
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis*; D045744:Cell Line, Tumor; D002851:Chromatography, High Pressure Liquid; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D015536:Down-Regulation; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism; D009062:Mouth Neoplasms / Q000378:metabolism / Q000473:pathology; D014411:Neoplastic Stem Cells / Q000166:cytology / Q000378:metabolism*; D010735:Phosphoglycerate Kinase / Q000378:metabolism; D040901:Proteomics; D053719:Tandem Mass Spectrometry; D015854:Up-Regulation
chemical_list: D014408:Biomarkers, Tumor; C115163:CREB1 protein, human; D017362:Cyclic AMP Response Element-Binding Protein; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; C577282:PGK1 protein, human; D010735:Phosphoglycerate Kinase