Endothelial cells promote stem-like phenotype of glioma cells through activating the Hedgehog pathway.
Bottom Line: Microenvironmental regulation of cancer stem cells (CSCs) strongly influences the onset and spread of cancer.We observed that CD133(+) GSCs were located closely to Shh(+) endothelial cells in specimens of human glioblastoma multiforme (GBM).Knockdown of Smo in glioma cells led to a significant reduction of their CSC-like phenotype formation in vitro and in vivo.
Affiliation: Institute of Pathology and Southwest Cancer Centre, Southwest Hospital, Third Military Medical University and Key Laboratory of Tumour Immunopathology, Ministry of Education of China, Chongqing, 400038, People's Republic of China.Show MeSH
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Mentions: To explore the mechanism underlying the interaction between GSCs and ECs, we utilized transwell co-culture. Both GL261 and U251 cells were tested for their ability to form tumour spheres after being cultured with corresponding ECs. As shown in Figure 2, tumour spheres generated from both cells cultured with ECs were much larger than those generated from both cells in the absence of ECs (Figure 2A). Meanwhile, proliferation of GL261 cells was not affected by their interaction with b.END3 cells (see supplementary material, Figure S2A). A limiting dilution assay revealed that the sphere-forming capacity of GL261 and U251 cells precultured with ECs was higher than that of glioma cells alone (Figure 2B). FACS analysis demonstrated that CD133+ glioma cells were significantly enriched after being co-cultured with corresponding ECs (Figure 2C). In order to verify the effect of ECs on glioma cells in vivo, we performed grafted tumour experiments, using both subcutaneous and orthotopic transplantation. Our orthotopic transplanted tumour model revealed that co-injection of GL261 and b.END3 cells led to earlier deaths of mice (Figure 2D) with larger allografts (Figure 2E) than GL261 cells alone, which was also confirmed by subcutaneous transplantation experiments (see supplementary material, Figure S2B). Further investigation revealed that allografts generated by co-injection of GL261 and b.END3 cells contained more CD133+ GSCs (see supplementary material, Figure S2C), higher microvessel density (MVD; see supplementary material, Figure S2D) and Ki-67 index (see supplementary material, Figure S2E), as compared to the allografts generated from GL261 cells alone. Although the cell cycle of GL261 cells was not changed after co-culture with b.END3 cells, which is inconsistent with previous findings by others 25,26, the higher Ki67 index indicated that endothelial cells could enhance not only the CSC phenotype but also proliferation in glioma cells. Our data suggest that ECs enhance tumour initiation and growth, possibly through promoting CSC-like phenotype of glioma cells.
Affiliation: Institute of Pathology and Southwest Cancer Centre, Southwest Hospital, Third Military Medical University and Key Laboratory of Tumour Immunopathology, Ministry of Education of China, Chongqing, 400038, People's Republic of China.