The efficacy of combination therapy using adeno-associated virus—interferon β and trichostatin A in vitro and in a murine model of neuroblastoma

PurposeTrichostatin A (TSA) is a potent histone deacetylase inhibitor and has demonstrated significant antitumor activity against a variety of cancer cell lines. Type I interferons have also shown significant antitumor as well as antiangiogenic activity. In this study, we examined the effectiveness of combination therapy of TSA and interferon β (IFN-β) on human neuroblastoma cells in vitro and in vivo using a murine model of retroperitoneal neuroblastoma.Materials and MethodsFor in vitro experiments, plated human neuroblastoma cells (NB-1643 and NB-1691) were treated with vehicle or with IFN-β, TSA, or both for 24 hours. Cytotoxicity was assessed by counting cells and expressing the results as a percentage of controls. Expression of the tumor suppressor p21Waf1 was assessed by Western blot. For in vivo experiments, retroperitoneal neuroblastomas were established in severe combined immune deficiency (SCID) mice. Interferon β was given using a gene therapy approach, administering 1.5 × 1010 particles of an adeno-associated virus vector encoding human IFN-β (AAV hIFN-β) via tail vein as a single dose per mouse. Trichostatin A was given at a dose of 5 mg/kg every 48 hours subcutaneously. Treatment groups included controls, AAV hIFN-β alone, TSA alone, and AAV hIFN-β together with TSA. Tumor volume was assessed 2 weeks after the treatment began.ResultsAfter 24 hours, treatment with IFN-β, TSA, and a combination of both resulted in a 45.3%, 68.1%, and 75% reduction in cell count relative to controls in the NB-1691 cell line. In the NB-1643 line, cell counts were reduced by 23%, 58%, and 62.3% respectively. In addition, NB-1691 cells treated with TSA showed increased expression of p21Waf1 on Western blot. For in vivo experiments, control-, AAV hIFN-β–, TSA-, and combination-treated tumors had the following final volumes: 1577.7 ± 264.2 mm3 (n = 3); 128.5 ± 74.4 mm3 (n = 4; P = .0001); 1248.7 ± 673.9 mm3 (n = 4; P = .48); and 127.5 ± 36.8 mm3 (n = 4; P = .0007), respectively.ConclusionNeuroblastoma, because of its unique biology, continues to be a challenging tumor to treat, and many times these tumors are refractory to standard chemotherapeutic regimens. These data show that both TSA and IFN-β inhibit neuroblastoma growth and that the combination may potentially provide a unique way to treat this difficult disease.