title: Comprehensive proteome quantification reveals NgBR as a new regulator for epithelial-mesenchymal transition of breast tumor cells.
abstract: Nogo-B receptor (NgBR) is a type I receptor and specifically binds to ligand Nogo-B. Our previous work has shown that NgBR is highly expressed in human breast invasive ductal carcinoma. Here, comprehensive proteome quantification was performed to examine the alteration of protein expression profile in MDA-MB-231 breast tumor cells after knocking down NgBR using lentivirus-mediated shRNA approach. Among a total of 1771 proteins feasibly quantified, 994 proteins were quantified in two biological replicates with RSD <50%. There are 122 proteins significantly down-regulated in NgBR knockdown MDA-MB-231 breast tumor cells, such as vimentin and S100A4, well-known markers for mesenchymal cells, and CD44, a stemness indicator. The decrease of vimentin, S100A4 and CD44 protein expression levels was further confirmed by Western blot analysis. MDA-MB-231 cells are typical breast invasive ductal carcinoma cells showing mesenchymal phenotype. Cell morphology analysis demonstrates NgBR knockdown in MDA-MB-231 cells results in reversibility of epithelial-mesenchymal transition (EMT), which is one of the major mechanisms involved in breast cancer metastasis. Furthermore, we demonstrated that NgBR knockdown in MCF-7 cells significantly prevented the TGF-β-induced EMT process as determined by the morphology change, and staining of E-cadherin intercellular junction as well as the decreased expression of vimentin.
  
  
  CONCLUSIONS
  Our previous publication showed that NgBR is highly expressed in human breast invasive ductal carcinoma. However, the roles of NgBR and NgBR-mediated signaling pathway in breast tumor cells are still unclear. Here, we not only demonstrated that the quantitative proteomics analysis is a powerful tool to investigate the global biological function of NgBR, but also revealed that NgBR is involved in the transition of breast epithelial cells to mesenchymal stem cells, which is one of the major mechanisms involved in breast cancer metastasis. These findings provide new insights for understanding the roles of NgBR in regulating breast epithelial cell transform during the pathogenesis of breast cancer.
authors.affiliation: Division of Pediatric Surgery, Department of Surgery, Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI 53226, USA; Division of Pediatric Pathology, Department of Pathology, Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI 53226, USA; Key Laboratory of Separation Science for Analytical Chemistry, National Chromatographic R&A Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China.
authors.forename: Baofeng
authors.initials: B
authors.lastname: Zhao
authors.affiliation: Key Laboratory of Separation Science for Analytical Chemistry, National Chromatographic R&A Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Xu
authors.affiliation: Division of Pediatric Surgery, Department of Surgery, Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI 53226, USA; Division of Pediatric Pathology, Department of Pathology, Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
authors.forename: Wenquan
authors.initials: W
authors.lastname: Hu
authors.affiliation: Key Laboratory of Separation Science for Analytical Chemistry, National Chromatographic R&A Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China.
authors.forename: Chunxia
authors.initials: C
authors.lastname: Song
authors.affiliation: Key Laboratory of Separation Science for Analytical Chemistry, National Chromatographic R&A Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China.
authors.forename: Fangjun
authors.initials: F
authors.lastname: Wang
authors.affiliation: Division of Pediatric Surgery, Department of Surgery, Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI 53226, USA; Division of Pediatric Pathology, Department of Pathology, Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
authors.forename: Zhong
authors.initials: Z
authors.lastname: Liu
authors.affiliation: Key Laboratory of Separation Science for Analytical Chemistry, National Chromatographic R&A Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China.
authors.forename: Mingliang
authors.initials: M
authors.lastname: Ye
authors.affiliation: Key Laboratory of Separation Science for Analytical Chemistry, National Chromatographic R&A Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China. Electronic address: hanfazou@dicp.ac.cn.
authors.forename: Hanfa
authors.initials: H
authors.lastname: Zou
authors.affiliation: Division of Pediatric Surgery, Department of Surgery, Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI 53226, USA; Division of Pediatric Pathology, Department of Pathology, Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI 53226, USA. Electronic address: qmiao@mcw.edu.
authors.forename: Qing R
authors.initials: QR
authors.lastname: Miao
mesh_terms: D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D058750:Epithelial-Mesenchymal Transition; D005260:Female; D006801:Humans; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D020543:Proteome / Q000235:genetics / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*
chemical_list: C512614:NUS1 protein, human; D009363:Neoplasm Proteins; D020543:Proteome; D011956:Receptors, Cell Surface
keywords: Breast cancer; Epithelial–mesenchymal transition; Nogo-B receptor; Quantitative proteomics