Quiescent glioblastoma cells shift to an epithelial-mesenchymal transition-like gene program

Quiescent stem cells of glioblastoma (GBM), a malignant primary brain tumor, are potential sources for recurrence after therapy. However, the gene expression program underlying the physiology of GBM stem cells remains unclear. We have isolated quiescent GBM cells by engineering them with a knock-in H2B-GFP proliferation reporter and expanding them in a 3D tumor organoid model that mimics tumor heterogeneity. H2B-GFP label retaining quiescent cells were subjected to stem cell assays and RNA-Seq gene expression analysis. While quiescent GBM cells were similar in clonal culture assays to their proliferative counterparts, they displayed higher therapy resistance. Interestingly, quiescent GBM cells upregulated epithelial-mesenchymal transition (EMT) genes and genes of extracellular matrix components. Our findings connect quiescent GBM cells with an EMT-like shift, possibly explaining how GBM stem cells achieve high therapy resistance and invasiveness, and suggest new targets to abrogate GBM. Overall design: Glioblastoma cancer cells in 3D organoid culture were pulsed for 2 weeks with H2B-GFP, then chased either 2 or 4 weeks. Label-retaining GFP-high cells (quiescent) were separated from bulk population, and both populations were analyzed by RNA-Seq.

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Tejero R, Huang Y, Katsyv I, Kluge M, Lin JY, Tome-Garcia J, Daviaud N, Wang Y, Zhang B, Tsankova NM, Friedel CC, Zou H, Friedel RH