ABSTRACT
Acute lymphoblastic leukemia (ALL) harboring the t(4;11) translocation is associated with a very poor prognosis; innovative treatment strategies are required to improve the current 5-year survival rate of 30-40%. Interferon beta (IFN beta) has shown promise in the treatment of both solid and hematologic malignancies, although the short half-life and toxicity associated with high doses have limited its clinical utility. To overcome these limitations, we investigated the effect of continuous, gene transfer-mediated delivery of IFN beta using adeno-associated virus (AAV)-mediated expression, on ALL cells with the t(4;11) translocation. We found that this method of IFN beta delivery resulted in complete remission of leukemia in a murine model. However, leukemic cells eventually became resistant to IFN beta and relapse was observed. Activation of NF-kappaB was identified as a mechanism for IFN beta resistance, and inhibition of NF-kappaB activity in resistant cells sensitized cells to IFN beta. IFN beta combined with agents that inhibit NF-kappaB could have therapeutic potential in the treatment of children with mixed lineage leukemia subtype ALL.
Subject(s)
Antineoplastic Agents/pharmacology , Gene Expression Regulation, Leukemic , Gene Rearrangement , Interferon-beta/pharmacology , Myeloid-Lymphoid Leukemia Protein/genetics , NF-kappa B/metabolism , Precursor Cell Lymphoblastic Leukemia-Lymphoma/metabolism , Adaptor Proteins, Signal Transducing/genetics , Adaptor Proteins, Signal Transducing/metabolism , Animals , Apoptosis/drug effects , Blotting, Western , Cell Line, Tumor , Cell Proliferation/drug effects , Chromosomes, Human, Pair 11/genetics , Chromosomes, Human, Pair 4/genetics , Dependovirus/genetics , Drug Resistance, Neoplasm , Electrophoretic Mobility Shift Assay , Flow Cytometry , Humans , JNK Mitogen-Activated Protein Kinases/genetics , JNK Mitogen-Activated Protein Kinases/metabolism , Male , Mice , Mice, SCID , Myeloid-Lymphoid Leukemia Protein/metabolism , NF-kappa B/genetics , Precursor Cell Lymphoblastic Leukemia-Lymphoma/drug therapy , Precursor Cell Lymphoblastic Leukemia-Lymphoma/genetics , RNA, Messenger/genetics , RNA, Messenger/metabolism , Reverse Transcriptase Polymerase Chain Reaction , Translocation, Genetic , Tumor Cells, Cultured , Xenograft Model Antitumor AssaysABSTRACT
Type I interferons (alpha/beta) have significant antitumor activity although their short half-life and systemic side effects have limited their clinical utility. An alternative dosing schedule of continuous, low-level delivery, as is achieved by gene therapy, rather than intermittent, high concentration pulsed-dosing, might avoid the toxicity of interferon while maintaining its antitumor efficacy. We have tested a gene therapy approach in murine tumor models to treat malignancies that have shown responsiveness to interferon in clinical trials. The tumor cell lines used were moderately sensitive to the direct effects of human interferon-beta (hIFN-beta) in vitro. For in vivo testing, systemic delivery of hIFN-beta was generated following liver-targeted delivery of adeno-associated virus (AAV) vector carrying the hIFN-beta transgene. This prevented engraftment of subcutaneous human gliomas, and orthotopic, localized (intrarenal) and disseminated (primarily pulmonary) human renal cell carcinomas; and caused regression of established tumors at these sites. In a syngeneic, immunocompetent model of melanoma, AAV IFN-beta treatment limited subcutaneous tumor growth and prevented disseminated disease. A significant decrease in mean intratumoral vessel density was demonstrated in hIFN-beta-treated tumors, suggesting that in addition to a direct tumoricidal effect, the antitumor efficacy of AAV IFN-beta in this study was due to its ability to inhibit angiogenesis.
