Oncolytic HSV-mediated Regulation of the Host Hypoxia Response
Loading...
Date
2014-03-26
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Glioblastoma (GBM) is the most common and deadly primary brain tumor, accounting for over 10,000 new cancer diagnoses in the United States each year. The poor prognosis for GBM patients necessitates novel biological treatments. One such approach is the use of oncolytic herpes simplex virus 1 (oHSV). Like many novel treatments, oHSV therapy causes side effects that are not yet well understood. Our lab has demonstrated that oHSV treatment increases the vascularity of brain tumors. The goal of this study is to determine the mechanism by which oHSV treatment increases the vascularity of brain tumors. We have determined that the hypoxia inducible factor-1 alpha (HIF1α) is activated in cells infected with oHSV, even in normal oxygen conditions. HIF1α is a transcription factor which activates a variety of genes in response to a lack of oxygen. We believe that HIF1α activation may be responsible for the increased vascularity of oHSV treated brain tumors. A screen of targetscan.org for herpes simplex virus 1 (HSV-1) miRNAs and their predicted target genes revealed multiple miRNAs predicted to target a protein called, factor inhibiting HIF1α (FIH). This protein functionally inhibits HIF1α activation by preventing the binding of HIF1α to DNA. We hypothesized that FIH would be negatively regulated in GBM cells infected with oHSV, thus allowing HIF1α activation. In this study, we demonstrate that HSV-1 expresses two miRNA molecules, which target and down regulate FIH. Transfection of miRNA inhibitors (antagomirs) was able to successfully abrogate the virus' ability to downregulate FIH as demonstrated by quantitative PCR and western blot. Moreover, transfection of HSV-1 miRNA mimics in the absence of virus was able to downregulate FIH protein levels (western blot) and activate the expression of a variety of HIF1α driven genes, including VEGF and CCN1 (quantitative PCR). Our future aim is to determine if HSV-1 encodes for miRNA capable of binding to the 3' untranslated region (3' UTR) of FIH. For this study we will employ an FIH-3' UTR luciferase reporter vector. This experiment will demonstrate if the miRNA expressed by oHSV directly binds to the 3' UTR of FIH, thus inhibiting FIH gene expression, and activating HIF1α.
Description
Biological Sciences: 2nd Place (The Ohio State University Denman Undergraduate Research Forum)
Keywords
Cancer, Oncolytic Virus, Microenvironment, Glioma, Micro RNA, Transcription Factor