Patient-Specific Screening Using High-Grade Glioma Explants to Determine Potential Radiosensitization by a TGF-? Small Molecule Inhibitor.
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ABSTRACT: High-grade glioma (HGG), a deadly primary brain malignancy, manifests radioresistance mediated by cell-intrinsic and microenvironmental mechanisms. High levels of the cytokine transforming growth factor-? (TGF-?) in HGG promote radioresistance by enforcing an effective DNA damage response and supporting glioma stem cell self-renewal. Our analysis of HGG TCGA data and immunohistochemical staining of phosphorylated Smad2, which is the main transducer of canonical TGF-? signaling, indicated variable levels of TGF-? pathway activation across HGG tumors. These data suggest that evaluating the putative benefit of inhibiting TGF-? during radiotherapy requires personalized screening. Thus, we used explant cultures of seven HGG specimens as a rapid, patient-specific ex vivo platform to test the hypothesis that LY364947, a small molecule inhibitor of the TGF-? type I receptor, acts as a radiosensitizer in HGG. Immunofluorescence detection and image analysis of ?-H2AX foci, a marker of cellular recognition of radiation-induced DNA damage, and Sox2, a stem cell marker that increases post-radiation, indicated that LY364947 blocked these radiation responses in five of seven specimens. Collectively, our findings suggest that TGF-? signaling increases radioresistance in most, but not all, HGGs. We propose that short-term culture of HGG explants provides a flexible and rapid platform for screening context-dependent efficacy of radiosensitizing agents in patient-specific fashion. This time- and cost-effective approach could be used to personalize treatment plans in HGG patients.
SUBMITTER: Bayin NS
PROVIDER: S-EPMC5156509 | biostudies-literature | 2016 Dec
REPOSITORIES: biostudies-literature
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