Isolation and characterization of tumorspheres from a recurrent pineoblastoma patient: Feasibility of a patient-derived xenograft.

Abstract

The existence oftumorspheres(TSs) might confer treatment resistance topineoblastoma(PB). The existence of PB TSs with cellular immortalization potential has not yet been reported. We developed a procedure for isolating TSs fromrecurrentPB (rPB) and tested whether their properties made them suitable for use as apatient-derivedxenograft(PDX). Immunocytochemical staining, RT-PCR and quantitative real-time PCR showed that, among stemness proteins, CD133, musashi and podoplanin were expressed at elevated levels in rPB TSs, but nestin was not. rPB TSs cultured under neuro-glial differentiation conditions expressed TUBB3, but not GFAP, MBP or NeuN. Unlike glioblastoma TSs, rPB TSs showed no clear evidence of invasion in 3D invasion assay or increased expression of genes associated with epithelial-mesenchymal transition. An orthotopicxenograftshowed that tumor xenografts replicated the histopathological features of thepatienttumor and expressed similar genome profiles, as determined by short tandem repeat genotyping. These data demonstrate theisolationand thecharacterizationof rPB TSs for the first time. Using an orthotopicxenograft, we showed that rPB TSs could replicate thepatienttumor, demonstrating their potential as a PDX for precision medicine.