Adams B, Zwernik S, Raymond D, Rovin R, Akhtar P. Zika virus targets stem cell markers and modulates antiviral responses in glioblastoma cancer stem cells. Poster presented at: Aurora Scientific Day; May 20, 2020; virtual webinar hosted in Milwaukee, WI.
Poster presented at: Aurora Scientific Day; May 20, 2020; virtual webinar hosted in Milwaukee, WI.
Background: Glioblastoma is the most common and lethal form of brain cancer. Standard treatment involves surgery, chemotherapy, and radiation. Tumor recurrence is caused by a population of glioblastoma cancer stem cells (GSCs) that resist and survive treatment. There are currently no pharmacological agents available for specific targeting of GSCs. Zika virus (ZIKV) is a flavivirus that targets normal neural stem cells in the developing brain and causes microcephaly. ZIKV also selectively targets GSCs in a similar manner. We examined the effect of ZIKV on specific stem cell markers as well as antiviral responses in patient-derived GSCs.
Purpose: To understand the oncolytic mechanism of ZIKV toward GSCs.
Methods: Glioblastoma patient-derived cell lines were acquired from within our institution and used for the entirety of this study. Patient-derived cell lines were grown in spheres using supplemented neurocult media. ZIKV strain MR766 was propagated in Vero cells, and viral stock was titrated by plaque assays. Glioblastoma patient cell lines were infected with ZIKV at a multiplicity of infection of 1. The percentage of infection was quantified by flow cytometry using a pan-flavivirus antibody. Western blotting was used to characterize protein expression, while qRT-PCR was used to quantify gene expression pre- and post-ZIKV infection in patient-derived cell lines.
Results: We tested multiple stem cell markers and found that Sox2 and Nestin expression is highly upregulated in our glioblastoma patient-derived cell lines (7714, 7730, 7753), while Nanog, Oct-4, and Musashi-1 were at basal levels. We further found that both Sox2 and Nestin were significantly decreased post-ZIKV infection. Next, we found that ZIKV induces antiviral responses postinfection through an increase of interferon-induced genes IRF1, IFIT1, ISG15, and IL6. Lastly, we found increased expression of FGF2 and Caspase-3 post-ZIKV infection, which are involved in cell differentiation and cell death, respectively.
Conclusion: Our results suggest that Zika virus infection causes loss of glioblastoma stem cell self-renewal through decreased Sox2 and Nestin expression. Furthermore, ZIKV leads to antiviral responses in GSCs through an increase of multiple interferon-induced genes. Finally, genes involved in cell differentiation and cell death are upregulated in GSCs post-ZIKV infection. Thus, there are multiple mechanisms to explain GSC death following ZIKV infection.