title: Restoration of PPP2CA expression reverses epithelial-to-mesenchymal transition and suppresses prostate tumour growth and metastasis in an orthotopic mouse model.
abstract: BACKGROUND
  Emergence of castration-resistance in prostate cancer (PCa) is invariably associated with aggressive and metastatic disease. Previously, we reported promotion of castration-resistance upon downregulation of PPP2CA (encoding catalytic subunit of protein phosphatase 2A (PP2A), α-isoform); however, its role in PCa growth and metastasis remained undetermined.
  
  
  METHODS
  PPP2CA was overexpressed/silenced in PCa cells by stable transfection. Gene expression was examined by reverse transcription polymerase chain reaction, immunoblot and immunofluorescence analyses, and transcriptional activity measured by luciferase-based promoter-reporter assay. Effect on PCa phenotype was studied in vitro and in orthotopic mouse model, and immunohistochemical/histological analyses performed to assess proliferation/apoptosis and confirm metastatic lesions.
  
  
  RESULTS
  An inverse association of PPP2CA expression was observed with epithelial-to-mesenchymal transition (EMT) and aggressive PCa phenotype. PPP2CA restoration resulted in decreased nuclear accumulation and transcriptional activity of β-catenin/NF-κB, and restitution of their activity abrogated PPP2CA-induced EMT reversal and suppression of PCa invasiveness. Akt mediated PPP2CA loss-induced nuclear accumulation of β-catenin/NF-κB through inactivation of Gsk3-β and IκB-α, respectively. Animal studies revealed a suppressive effect of PPP2CA expression on PCa growth and metastasis.
  
  
  CONCLUSIONS
  Our findings suggest that PPP2CA downregulation serves as a molecular link between gain of castration-resistance and aggressive PCa phenotype, and its restoration could be an effective preventive/therapeutic approach against the advanced disease.
authors.affiliation: Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, Mobile, AL 36604, USA.
authors.forename: A
authors.initials: A
authors.lastname: Bhardwaj
authors.affiliation: Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, Mobile, AL 36604, USA.
authors.forename: S
authors.initials: S
authors.lastname: Singh
authors.affiliation: Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, Mobile, AL 36604, USA.
authors.forename: S K
authors.initials: SK
authors.lastname: Srivastava
authors.affiliation: Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, Mobile, AL 36604, USA.
authors.forename: S
authors.initials: S
authors.lastname: Arora
authors.affiliation: Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, Mobile, AL 36604, USA.
authors.forename: S J
authors.initials: SJ
authors.lastname: Hyde
authors.affiliation: Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, Mobile, AL 36604, USA.
authors.forename: J
authors.initials: J
authors.lastname: Andrews
authors.affiliation: Department of Pathology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
authors.forename: W E
authors.initials: WE
authors.lastname: Grizzle
authors.affiliation: 1] Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, Mobile, AL 36604, USA [2] Department of Biochemistry and Molecular Biology, College of Medicine, University of South Alabama, Mobile, AL 36688, USA.
authors.forename: A P
authors.initials: AP
authors.lastname: Singh
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D058750:Epithelial-Mesenchymal Transition / Q000235:genetics*; D015972:Gene Expression Regulation, Neoplastic; D055785:Gene Knockdown Techniques; D006801:Humans; D008297:Male; D051379:Mice; D058990:Molecular Targeted Therapy; D009362:Neoplasm Metastasis / Q000235:genetics / Q000473:pathology; D064129:Prostatic Neoplasms, Castration-Resistant / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D054648:Protein Phosphatase 2 / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics*; D015398:Signal Transduction
chemical_list: C517189:PPP2CA protein, human; D054648:Protein Phosphatase 2