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Patient-Derived Brain Tumour iPSCs: Models for Investigating Glioma Stemness & Drug Discovery

May 8th 2018

Self-renewal capability (a stem cell-like feature), when unregulated, has been implicated in glioma treatment resistance and tumour recurrence. Drugs that eliminate tumour cells possessing this malignant characteristic are urgently needed. It remains, however, an experimental challenge to link heterogeneous glioma genotypes to drug response at scale.

University of Leeds, in participation with Censo Biotechnologies, has successfully derived patient-specific induced pluripotent stem cell (iPSC) models from both low- (LGG) and high-grade gliomas (HGG) and developed an initial drug discovery application. Censo Biotechnologies was involved in the RNAseq and in vitro assay data and is in the process of deriving iPSC from HGG only.

Methods

Brain tumour tissue, acquired at surgery, was reprogrammed. Derived iPSC models were characterised using pluripotency markers, tri-germinal layer differentiation, gene expression, karyology and deep whole genome sequencing (WGS, iPSC versus parental tumour). Glioma iPSC differentiation in 2-dimensional (adherent, optically clear 96-well imaging plates) and 3-dimensional (organoid) culture was carried out. Gene expression of neural induction and neuronal differentiation was analysed using mRNA-seq. Neural cancer stem cells from each glioma iPSC line were orthotopically implanted in vivo.

Results

Reprogrammed cells were confirmed as fully-reprogramed/stable iPSCs, with mutational variants (SNPs, CNVs) preserved as compared to the parental tumours. Glioma iPSC maturation and quantification of TUJ-1 expression indicated a ‘differentiation block’ in the HGG iPSC models. This phenotype was concordant in HGG iPSC-derived tumour organoids which displayed SOX2/MKI67-positive neural rosettes. Consistently, mice developed xenograft tumours with GBM characteristics. Expression profiling during neuronal differentiation (from iPSC to neural stem cells to neurons) has revealed candidate genes that may be responsible for the phenotypic differences between HGG and control/LGG iPSC models.

Conclusions

The iPSC models may uncover genetic mutations and regulatory networks underlying glioma stem cell self-renewal, and provide a basis for industrial-scale drug discovery. The first stages towards this development (in a 96-well assay format) have been successfully implemented. Ultimately, this iPSC-based approach may enable personalised precision medicine strategies against glioma.

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This poster was presented at the inaugural Cancer Research UK (CRUK) Brain Tumour Conference.

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