title: Targeted inhibition of mitochondrial Hsp90 suppresses localised and metastatic prostate cancer growth in a genetic mouse model of disease.
abstract: BACKGROUND
  The molecular chaperone heat shock protein-90 (Hsp90) is a promising cancer drug target, but current Hsp90-based therapy has so far shown limited activity in the clinic.
  
  
  METHODS
  We tested the efficacy of a novel mitochondrial-targeted, small-molecule Hsp90 inhibitor, Gamitrinib (GA mitochondrial matrix inhibitor), in the Transgenic Adenocarcinoma of the Mouse Prostate (TRAMP) model. The TRAMP mice receiving 3-week or 5-week systemic treatment with Gamitrinib were evaluated for localised or metastatic prostate cancer, prostatic intraepithelial neoplasia (PIN) or localised inflammation using magnetic resonance imaging, histology and immunohistochemistry. Treatment safety was assessed histologically in organs collected at the end of treatment. The effect of Gamitrinib on mitochondrial dysfunction was studied in RM1 cells isolated from TRAMP tumours.
  
  
  RESULTS
  Systemic administration of Gamitrinib to TRAMP mice inhibited the formation of localised prostate tumours of neuroendocrine or adenocarcinoma origin, as well as metastatic prostate cancer to abdominal lymph nodes and liver. The Gamitrinib treatment had no effect on PIN or prostatic inflammation, and caused no significant animal weight loss or organ toxicity. Mechanistically, Gamitrinib triggered acute mitochondrial dysfunction in RM1 cells, with loss of organelle inner membrane potential and release of cytochrome-c in the cytosol.
  
  
  CONCLUSIONS
  The Gamitrinib has pre-clinical activity and favourable tolerability in a genetic model of localised and metastatic prostate cancer in immunocompetent mice. Selective targeting of mitochondrial Hsp90 could provide novel molecular therapy for patients with advanced prostate cancer.
authors.affiliation: Prostate Cancer Discovery and Development Program, 3601 Spruce Street, Philadelphia, PA 19104, USA.
authors.forename: B H
authors.initials: BH
authors.lastname: Kang
authors.forename: M
authors.initials: M
authors.lastname: Tavecchio
authors.forename: H L
authors.initials: HL
authors.lastname: Goel
authors.forename: C-C
authors.initials: CC
authors.lastname: Hsieh
authors.forename: D S
authors.initials: DS
authors.lastname: Garlick
authors.forename: C M
authors.initials: CM
authors.lastname: Raskett
authors.forename: J B
authors.initials: JB
authors.lastname: Lian
authors.forename: G S
authors.initials: GS
authors.lastname: Stein
authors.forename: L R
authors.initials: LR
authors.lastname: Languino
authors.forename: D C
authors.initials: DC
authors.lastname: Altieri
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics / Q000473:pathology / Q000517:prevention & control*; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology / Q000627:therapeutic use*; D049109:Cell Proliferation / Q000187:drug effects*; D002478:Cells, Cultured; D004195:Disease Models, Animal; D018450:Disease Progression; D004353:Drug Evaluation, Preclinical; D005260:Female; D020022:Genetic Predisposition to Disease; D006146:Guanidines / Q000494:pharmacology / Q000627:therapeutic use*; D018841:HSP90 Heat-Shock Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D047029:Lactams, Macrocyclic / Q000494:pharmacology / Q000627:therapeutic use*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D058990:Molecular Targeted Therapy / Q000379:methods; D009362:Neoplasm Metastasis; D019048:Prostatic Intraepithelial Neoplasia / Q000235:genetics / Q000473:pathology / Q000517:prevention & control; D011471:Prostatic Neoplasms / Q000235:genetics / Q000473:pathology / Q000517:prevention & control*
chemical_list: D000970:Antineoplastic Agents; D006146:Guanidines; D018841:HSP90 Heat-Shock Proteins; D047029:Lactams, Macrocyclic; C557898:gamitrinib-G4