title: Synergistic growth inhibition based on small-molecule p53 activation as treatment for intraocular melanoma.
abstract: The prognosis of patients with uveal melanoma is poor. Because of the limited efficacy of current treatments, new therapeutic strategies need to be developed. Because p53 mutations are uncommon in uveal melanoma, reactivation of p53 may be used to achieve tumor regression. We investigated the use of combination therapies for intraocular melanoma, based on the p53 activators Nutlin-3 and reactivation of p53 and induction of tumor cell apoptosis (RITA) and the topoisomerase I inhibitor Topotecan. Nutlin-3 treatment induced p53-dependent growth inhibition in human uveal melanoma cell lines. The sensitivity to Nutlin-3 of the investigated cell lines did not correlate with basal Hdm2 or Hdmx levels. Nutlin-3 synergized with RITA and Topotecan to induce apoptosis in uveal melanoma cell lines and short-term cultures. Drug synergy correlated with enhanced induction of p53-Ser46 phosphorylation, which was attenuated by ATM inhibition. Nutlin-3 and Topotecan also significantly delayed tumor growth in vivo in a murine B16F10 model for ocular melanoma. Combination treatment appeared to inhibit tumor growth slightly more efficient than either drug alone. Nutlin-3, RITA and Topotecan lead to comparable p53 activation and growth inhibition under normoxia and hypoxia. Treatment with Nutlin-3 or RITA had no effect on HIF-1α induction by hypoxia, whereas the combination of these two drugs did inhibit hypoxia-induced HIF-1α. Also Topotecan, alone or in combination with Nutlin-3, reduced HIF-1α protein levels, suggesting that a certain level of DNA damage response is required for p53-mediated downregulation of HIF-1α. In conclusion, combination treatments based on small-molecule-induced p53 activation may have clinical potential for uveal melanoma.
authors.affiliation: Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: de Lange
authors.forename: L V
authors.initials: LV
authors.lastname: Ly
authors.forename: K
authors.initials: K
authors.lastname: Lodder
authors.forename: M
authors.initials: M
authors.lastname: Verlaan-de Vries
authors.forename: A F A S
authors.initials: AF
authors.lastname: Teunisse
authors.forename: M J
authors.initials: MJ
authors.lastname: Jager
authors.forename: A G
authors.initials: AG
authors.lastname: Jochemsen
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology / Q000627:therapeutic use*; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins / Q000037:antagonists & inhibitors; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors; D004357:Drug Synergism; D005663:Furans / Q000494:pharmacology / Q000627:therapeutic use; D006801:Humans; D000860:Hypoxia; D007093:Imidazoles / Q000494:pharmacology / Q000627:therapeutic use; D008545:Melanoma / Q000188:drug therapy* / Q000235:genetics; D008546:Melanoma, Experimental / Q000188:drug therapy / Q000235:genetics; D051379:Mice; D010766:Phosphorylation / Q000187:drug effects; D010879:Piperazines / Q000494:pharmacology / Q000627:therapeutic use; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors; D019772:Topotecan / Q000494:pharmacology / Q000627:therapeutic use; D016159:Tumor Suppressor Protein p53 / Q000819:agonists* / Q000235:genetics; D025521:Tumor Suppressor Proteins / Q000037:antagonists & inhibitors; D014604:Uveal Neoplasms / Q000188:drug therapy* / Q000235:genetics; D000098943:Uveal Melanoma
chemical_list: D000970:Antineoplastic Agents; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D005663:Furans; D007093:Imidazoles; C118989:NSC 652287; D010879:Piperazines; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; C482205:nutlin 3; D019772:Topotecan; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C576325:Atm protein, mouse; D017346:Protein Serine-Threonine Kinases