title: Differential proteomic analysis on the effects of 2-methoxy-1,4-naphthoquinone towards MDA-MB-231 cell line.
abstract: BACKGROUND
  We have previously reported the anti-metastatic effects of 2-methoxy-1,4-naphthoquinone (MNQ) against MDA-MB-231 cell line.
  
  
  OBJECTIVE
  To investigate the molecular mechanism underlying the anti-metastatic effects of MNQ towards MDA-MB-231 cell line via the comparative proteomic approach.
  
  
  METHODS
  Differentially expressed proteins in MNQ-treated MDA-MB-231 cells were identified by using two-dimensional gel electrophoresis coupled with tandem mass spectrometry. Proteins and signalling pathways associated with the identified MNQ-altered proteins were studied by using Western blotting.
  
  
  RESULTS
  Significant modulation of MDA-MB-231 cell proteome was observed upon treatment with MNQ in which the expressions of 19 proteins were found to be downregulated whereas another eight were upregulated (>1.5 fold, p < 0.05). The altered proteins were mainly related to cytoskeletal functions and regulations, mRNA processing, protein modifications and oxidative stress response. Notably, two of the downregulated proteins, protein S100-A4 (S100A4) and laminin-binding protein (RPSA) are known to play key roles in driving metastasis and were verified using Western blotting. Further investigation using Western blotting also revealed that MNQ decreased the activations of pro-metastatic ERK1/2 and NF-κB signalling pathways. Moreover, MNQ was shown to stimulate the expression of the metastatic suppressor, E-cadherin.
  
  
  CONCLUSIONS
  This study reports a proposed mechanism by which MNQ exerts its anti-metastatic effects against MDA-MB-231 cell line. The findings from this study offer new insights on the potential of MNQ to be developed as a novel anti-metastatic agent.
authors.affiliation: School of Biosciences, Taylor's University, No.1 Jalan Taylor's, 47500 Subang Jaya, Selangor Darul Ehsan, Malaysia. Electronic address: kitson_liew@hotmail.com.
authors.forename: Kitson
authors.initials: K
authors.lastname: Liew
authors.affiliation: School of Biosciences, Taylor's University, No.1 Jalan Taylor's, 47500 Subang Jaya, Selangor Darul Ehsan, Malaysia. Electronic address: phelim.yong@taylors.edu.my.
authors.forename: Phelim Voon Chen
authors.initials: PV
authors.lastname: Yong
authors.affiliation: School of Biosciences, Taylor's University, No.1 Jalan Taylor's, 47500 Subang Jaya, Selangor Darul Ehsan, Malaysia. Electronic address: nava.vis@taylors.edu.my.
authors.forename: Visweswaran
authors.initials: V
authors.lastname: Navaratnam
authors.affiliation: Department of Pre-Clinical Sciences, Faculty of Medicine and Health Sciences, Universiti Tunku Abdul Rahman, Lot PT21144, Jalan Sungai Long, Bandar Sungai Long, 43000 Kajang, Selangor Darul Ehsan, Malaysia. Electronic address: ymlim@utar.edu.my.
authors.forename: Yang Mooi
authors.initials: YM
authors.lastname: Lim
authors.affiliation: School of Biosciences, Taylor's University, No.1 Jalan Taylor's, 47500 Subang Jaya, Selangor Darul Ehsan, Malaysia. Electronic address: anthony.ho@taylors.edu.my.
authors.forename: Anthony Siong Hock
authors.initials: AS
authors.lastname: Ho
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D045744:Cell Line, Tumor / Q000187:drug effects; D006801:Humans; D009285:Naphthoquinones / Q000494:pharmacology*; D020543:Proteome / Q000378:metabolism*; D040901:Proteomics
chemical_list: D000970:Antineoplastic Agents; D009285:Naphthoquinones; D020543:Proteome; C096118:2-methoxy-1,4-naphthoquinone
keywords: 2-Methoxy-1,4-naphthoquinone; E-cadherin; ERK1/2; NF-κB; RPSA; S100A4