Evaluation of the In vitro and In vivo Antitumor Activity of Histone Deacetylase Inhibitors for the Therapy of Retinoblastoma

• Published in: Clinical cancer research Vol. 14; no. 10; pp. 3113 - 3123
• Main Authors: Dalgard, Clifton Lee, Van Quill, Kurtis R, O'Brien, Joan M
• Format: Journal Article
• Language: English
• Published: United States American Association for Cancer Research 15.05.2008
• Subjects: Animals; Annexin A5 - drug effects; Antineoplastic Agents - pharmacology; Apoptosis - drug effects; Benzamides - pharmacology; Blotting, Western; Caspase 3 - drug effects; Caspase 7 - drug effects; Cell Proliferation - drug effects; Cell Survival - drug effects; Enzyme Inhibitors - pharmacology; Flow Cytometry; histone deacetylase inhibitor; Histone Deacetylase Inhibitors; Humans; Hydroxamic Acids - pharmacology; In Vitro Techniques; Mice; Mice, Transgenic; MS-275; Polymerase Chain Reaction; Pyridines - pharmacology; Rats; Reactive Oxygen Species - metabolism; Retinal Neoplasms - drug therapy; retinoblastoma; Retinoblastoma - drug therapy; Xenograft Model Antitumor Assays
• ISSN: 1078-0432; 1557-3265
• DOI: 10.1158/1078-0432.CCR-07-4836

Purpose: To evaluate the potential utility of histone deacetylase inhibitors (HDACi) for treatment of retinoblastoma (RB). Experimental Design: Growth-inhibitory effects of HDACi [trichostatin A (TSA), suberoylanilide hydroxamic acid (SAHA), or MS-275] were assessed in human and transgenic murine RB cells. Effects of TSA and MS-275 were also assessed in combination with standard therapeutic agents for RB. Proapoptotic effects of MS-275 and TSA were evaluated by caspase-3/7 activity, Annexin V translocation, and/or Bim expression analyses. Effects of MS-275 on cell cycle distribution and reactive oxygen species levels were determined by flow cytometry. Retinal tissue morphology was evaluated in mice after local administration of MS-275. Analysis of retinal acetyl-histone levels was used to assess MS-275 delivery after systemic administration. Therapeutic effects of MS-275 were determined in transgenic mouse and rat ocular xenograft models of RB after i.p. injection of 20 mg/kg every other day for 21 or 13 days, respectively. Results: TSA, SAHA, and MS-275 dose dependently reduced RB cell survival. TSA and MS-275 showed additive growth-inhibitory effects in combination with carboplatin, etoposide, or vincristine. TSA and MS-275 increased caspase-3/7 activity. MS-275 increased Annexin V membrane translocation and induced G 1 arrest. Cytotoxicity of MS-275 was dependent on increased reactive oxygen species levels and was reversed by antioxidant pretreatment. Intraocular administration of 1 μL of 10 μmol/L MS-275 did not alter ocular tissue morphology. Increased acetyl-histone levels confirmed MS-275 delivery to retinal tissue after systemic administration. MS-275 significantly reduced tumor burden in both mouse and rat models of RB. Conclusions: HDACi should be considered for clinical trials in children with RB.