title: Plumbagin shows anti-cancer activity in human breast cancer cells by the upregulation of p53 and p21 and suppression of G1 cell cycle regulators.
abstract: OBJECTIVE
  Plumbagin, a naphthoquinone constituent of Plumbago zeylanica L. (Plumbaginaceae), is known to exhibit proapoptotic, antiangiogenic and antimetastatic effects in cancer cells. However, the effect of Plumbagin on breast cancer cells and the underlying molecular mechanism has not yet been elucidated.
  
  
  METHODS
  MCF-7 (a human breast cancer cell line) was exposed different concentrations of Plumbagin (PG), and the anti-proliferative activity was evaluated by the MTT assay. The mechanism of action for the growth inhibitory activity of Plumbagin on MCF-7 cancer cells was evaluated using flow cytometry for cell cycle distribution, and western blot for assessment of expression of potential target proteins.
  
  
  RESULTS
  Plumbagin exhibited a significant anti-proliferative activity against human breast cancer cells. Flow cytometric analysis revealed that Plumbagin caused cell cycle arrest at G1 phase. The cell cycle arrest was well correlated with the inhibition of cyclin D1, cyclin E, and upregulation of tumor suppressor protein p53. It further inhibited the expression of anti-apoptotic Bcl-2 family members such as Bcl-xL and Bcl-2, and activated pro-apoptotic proteins like Bax and Bak.
  
  
  CONCLUSIONS
  These findings suggest that the anti-proliferative effect of Plumbagin is due to upregulation of p53 and p21 and suppression of G1 cell cycle regulators.
authors.forename: X Q
authors.initials: XQ
authors.lastname: Zhang
authors.forename: C Y
authors.initials: CY
authors.lastname: Yang
authors.forename: X F
authors.initials: XF
authors.lastname: Rao
authors.forename: J P
authors.initials: JP
authors.lastname: Xiong
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D049109:Cell Proliferation / Q000187:drug effects; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics*; D059585:G1 Phase Cell Cycle Checkpoints / Q000187:drug effects*; D006801:Humans; D061986:MCF-7 Cells; D009285:Naphthoquinones / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000032:analysis; D016159:Tumor Suppressor Protein p53 / Q000235:genetics*; D015854:Up-Regulation
chemical_list: D000972:Antineoplastic Agents, Phytogenic; C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D009285:Naphthoquinones; D019253:Proto-Oncogene Proteins c-bcl-2; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; C014758:plumbagin