title: Notch3 induces epithelial-mesenchymal transition and attenuates carboplatin-induced apoptosis in ovarian cancer cells.
abstract: OBJECTIVE
  Notch3 is implicated in chemoresistance of ovarian cancer, yet the molecular mechanism underlying Notch3-mediated drug resistance remains to be elucidated. Here, we investigated the role of Notch3 in carboplatin-induced apoptosis in ovarian cancer cells.
  
  
  METHODS
  Ovarian cancer cell line OVCA429 cells were stably transduced with an empty vector or a retroviral vector expressing the Notch3 intracellular domain (NICD3, the constitutively active form of Notch3) to generate OVCA429/vector and OVCA429/NICD3 cells. Epithelial-mesenchymal transition (EMT) was determined by morphological change and expression of the EMT markers. Carboplatin-induced cytotoxicity was determined by the neutral red uptake assay. Apoptosis was determined by Annexin V staining and Western blotting. Carboplatin-induced phosphorylation of extracellular signal-regulated kinase (ERK) was identified by a phospho-kinase array and confirmed by Western blotting.
  
  
  RESULTS
  Activation of Notch3 in OVCA429 cells causes a spindle and fibroblast-like morphology, induces the expression of smooth muscle α-actin, Slug and Snail, but decreases the expression of E-cadherin, indicating that Notch3 activation induces EMT in OVCA429 cells. Furthermore, Notch3 activation renders OVCA429 cells more resistant to carboplatin-induced cytotoxicity and attenuates carboplatin-induced apoptosis in these cells. Our results indicate that phosphorylation of ERK is a positive regulator of carboplatin-induced apoptosis in OVCA429 cells. Interestingly, carboplatin-induced ERK phosphorylation is inhibited by Notch3 activation.
  
  
  CONCLUSIONS
  Notch3 activation induces EMT and attenuates carboplatin-induced apoptosis in OVCA429 cells. ERK phosphorylation plays a pro-apoptotic role in carboplatin-induced apoptosis in OVCA429 cells. Interestingly, Notch3 activation attenuates carboplatin-induced ERK phosphorylation in these cells.
authors.affiliation: Department of Obstetrics and Gynecology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada.
authors.forename: Nidhi
authors.initials: N
authors.lastname: Gupta
authors.forename: Zhihua
authors.initials: Z
authors.lastname: Xu
authors.forename: Ahmed
authors.initials: A
authors.lastname: El-Sehemy
authors.forename: Helen
authors.initials: H
authors.lastname: Steed
authors.forename: Yangxin
authors.initials: Y
authors.lastname: Fu
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D002070:Butadienes / Q000494:pharmacology; D016190:Carboplatin / Q000494:pharmacology*; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm; D058750:Epithelial-Mesenchymal Transition / Q000502:physiology*; D005260:Female; D006801:Humans; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism; D009570:Nitriles / Q000494:pharmacology; D010051:Ovarian Neoplasms / Q000188:drug therapy* / Q000378:metabolism* / Q000473:pathology; D010766:Phosphorylation / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D000071656:Receptor, Notch3; D051880:Receptors, Notch / Q000378:metabolism*
chemical_list: D000970:Antineoplastic Agents; D002070:Butadienes; C499374:NOTCH3 protein, human; D009570:Nitriles; D047428:Protein Kinase Inhibitors; D000071656:Receptor, Notch3; D051880:Receptors, Notch; C113580:U 0126; D016190:Carboplatin; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3