title: IFN-beta restricts tumor growth and sensitizes alveolar rhabdomyosarcoma to ionizing radiation.
abstract: Ionizing radiation is an important component of multimodal therapy for alveolar rhabdomyosarcoma (ARMS). We sought to evaluate the ability of IFN-beta to enhance the activity of ionizing radiation. Rh-30 and Rh-41 ARMS cells were treated with IFN-beta and ionizing radiation to assess synergistic effects in vitro and as orthotopic xenografts in CB17 severe combined immunodeficient mice. In addition to effects on tumor cell proliferation and xenograft growth, changes in the tumor microenvironment including interstitial fluid pressure, perfusion, oxygenation, and cellular histology were assessed. A nonlinear regression model and isobologram analysis indicated that IFN-beta and ionizing radiation affected antitumor synergy in vitro in the Rh-30 cell line; the activity was additive in the Rh-41 cell line. In vivo continuous delivery of IFN-beta affected normalization of the dysfunctional tumor vasculature of both Rh-30 and Rh-41 ARMS xenografts, decreasing tumor interstitial fluid pressure, increasing tumor perfusion (as assessed by contrast-enhanced ultrasonography), and increasing oxygenation. Tumors treated with both IFN-beta and radiation were smaller than control tumors and those treated with radiation or IFN-beta alone. Additionally, treatment with high-dose IFN-beta followed by radiation significantly reduced tumor size compared with radiation treatment followed by IFN-beta. The combination of IFN-beta and ionizing radiation showed synergy against ARMS by sensitizing tumor cells to the cytotoxic effects of ionizing radiation and by altering tumor vasculature, thereby improving oxygenation. Therefore, IFN-beta and ionizing radiation may be an effective combination for treatment of ARMS.
authors.affiliation: Department of Surgery, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA.
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Sims
authors.forename: Mackenzie
authors.initials: M
authors.lastname: McGee
authors.forename: Regan F
authors.initials: RF
authors.lastname: Williams
authors.forename: Adrianne L
authors.initials: AL
authors.lastname: Myers
authors.forename: Lorraine
authors.initials: L
authors.lastname: Tracey
authors.forename: J Blair
authors.initials: JB
authors.lastname: Hamner
authors.forename: Catherine
authors.initials: C
authors.lastname: Ng
authors.forename: Jianrong
authors.initials: J
authors.lastname: Wu
authors.forename: M Waleed
authors.initials: MW
authors.lastname: Gaber
authors.forename: Beth
authors.initials: B
authors.lastname: McCarville
authors.forename: Amit C
authors.initials: AC
authors.lastname: Nathwani
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Davidoff
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D006801:Humans; D016899:Interferon-beta / Q000494:pharmacology*; D008297:Male; D051379:Mice; D016513:Mice, SCID; D009389:Neovascularization, Pathologic / Q000532:radiotherapy; D010101:Oxygen Consumption / Q000187:drug effects; D011836:Radiation Tolerance / Q000187:drug effects*; D011839:Radiation, Ionizing; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology; D011994:Recombinant Proteins / Q000494:pharmacology; D018232:Rhabdomyosarcoma, Alveolar / Q000098:blood supply / Q000473:pathology / Q000532:radiotherapy*; D047368:Tumor Burden / Q000187:drug effects*; D023041:Xenograft Model Antitumor Assays
chemical_list: D011838:Radiation-Sensitizing Agents; D011994:Recombinant Proteins; D016899:Interferon-beta