Fig. 4. Overexpression of ETV2 reprograms p-GBM tumor cells into endothelial cells in vitro and in vivo.
a p-GBM cells (#109) were reprogramed into endothelial-like cells 1 week following ETV2 overexpression in vitro. Patient GBM cells were propagated as neurospheres under optimal conditions for neural stem cells. One week after ETV2 overexpression, partial p-GBM cells showed an endothelial morphology (red arrows) and the ability to express endothelial genes (VE-cad, flk-1, CD31, CD34, and tie2, among others) (white arrows). HUVECs were set as the positive control. Scale bar: 50 μm. b p-GBM cells (#109) were reprogramed into endothelial-like cells and arranged as vascular tubes in vivo. GBM #109-ETV2 or control GBM #109-YFP cells were orthotopically implanted into the brain of NOD/Scid mice (1 × 106 cells in each mouse, n = 5 per group). HE staining indicated the GBM tumors, areas in dotted boxes, are magnified on the right; blue circles indicate tumor blood vessels. b IF staining showed the tumor cell-derived ECs (hCD31+/ki67+ arrows). Scale bar: 50 μm. c Angiogenic growth factors were dispensable for endo-transdifferentiation of GBM tumor cells, but they were beneficial for TDEC enrichment. GBM #109 tumor cells infected with LV-ETV2-YFP or LV-YFP were cultured in basic endothelial medium free of growth factors or supplemented with VEGFa (50 ng/ml), bFGF (20 ng/ml), and EGF (10 ng/ml) for 5 days. The percentage of VE-Cad+ cells among the successfully infected YFP+ cells is indicated