Dissecting inherent intratumor heterogeneity in patient-derived glioblastoma culture models.

ABSTRACT: Molecular profile of glioblastoma multiforme (GBM) revealed 4 subtypes, 2 of which, proneural and mesenchymal, have been predominantly observed, with the latter displaying a more aggressive phenotype and increased therapeutic resistance. Single-cell RNA sequencing revealed that multiple subtypes actually reside within the same tumor, suggesting cellular heterogeneity in GBM. Further, plasticity between these 2 subtypes is observed during tumor recurrence and in response to radiation therapy.Patient-derived GBM stemlike cells were cultured as neurospheres. These cells were differentiated in serum by attaching to the culture dishes. The "floating" cells that were not attached/differentiated were harvested from the conditioned medium. The characteristics of these cells were studied with limiting dilution assays and immunofluorescence staining. Cell growth and nuclear factor-kappaB (NFkB) activation were monitored using bioluminescent assays as well as quantitative polymerase chain reaction and western blotting. In vivo tumorigenesis was evaluated in orthotopic xenograft models using bioluminescence imaging.Patient-derived GBM stemlike cells undergo differentiation by attaching to the culture dish in serum-containing medium. We observed that a small subset of these cells escape this adhesion/differentiation and grow as floating cells. These cells displayed enhanced cancer stem cell properties with a molecular and phenotypic mesenchymal signature, including resistance to radiation and targeted therapies, a more aggressive tumor formation, and NFkB activation.Our results endorse inherent intratumor molecular subtype heterogeneity in glioblastoma and provide a valuable approach to study phenotypic plasticity, which could be applied to find novel therapeutic strategies to eradicate this aggressive tumor and can be extended to other cancer types.

SUBMITTER: Teng J 

PROVIDER: S-EPMC5464448 | biostudies-other | 2017 Jun

REPOSITORIES: biostudies-other