Neuroblastoma is an aggressive pediatric cancer that is poorly responsive to traditional cancer therapies. Oncolytic viral (OV) vectors such as Zika virus (ZIKV) and Parainfluenza virus type 5 (P/V virus) are promising neuroblastoma therapeutics, but the role of innate immune responses in the effectiveness of OV killing is not well understood. Previous studies showed the neuroblastoma cell line SK-N-AS (expressing low CD24) had low permissivity for ZIKV infection, and this restriction was relieved by ectopic CD24 expression (CD24-high cells). Compared to permissive CD24-high cells, the non-permissive CD24-low cells had elevated basal levels of IRF-1, NF?B and phosphorylated STAT1; these cells also showed higher levels of interferon (IFN)-induced antiviral genes and activity against IFN- sensitive viruses (e.g., VSV). Media-transfer experiments showed that the inherent antiviral state of CD24-low cells was not dependent on a secreted factor. Transcriptomics analysis revealed that CD24 expression suppressed basal expression of antiviral genes. These data support the proposal that CD24 alters basal and induced antiviral states and may represent a novel biomarker for susceptibility of cells to OV infection. We extended these studies to test the hypothesis that epigenetic modulators could alter the antiviral state of neuroblastoma cells to enhance OV killing. Pre-treatment with the DNA methyltransferase inhibitor 5-Azacytidine enhanced P/V virus-mediated death of SK-N-AS cells in a dose- and MOI-dependent manner. While killing of SK-N-AS cells by the P/V virus alone was minimally caspase-dependent, combined treatment with 5-Azacytidine and P/V virus shifted cell killing to a largely caspase-dependent mechanism. 5-Azacytidine pre-treatment of SK-N-AS cells dampened P/V virus growth, which correlated with higher expression of antiviral mediators such as interferon-beta and OAS2. These studies demonstrate that antiviral responses mediated by a host factor (CD24) and by epigenetic modulators (5-Azacytidine) can be exploited to enhance tumor cell killing by RNA OVs.
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Doctor of Philosophy (Ph.D.)
College of Medicine
Burnett School of Biomedical Sciences
Length of Campus-only Access
Doctoral Dissertation (Open Access)
Kedarinath, Kritika, "Host Cell Responses Modulate Oncolytic Viral Treatment of Neuroblastoma Cells" (2023). Electronic Theses and Dissertations, 2020-. 1586.