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: Expression of Shh was detected in ECs. RT–PCR analysis showed that expression of Shh was dramatically up-regulated in the b.END3 cells co-cultured with GL261 cells (Figure 6A), and the concentration of Shh in the supernatant collected from co-cultured cells was much higher than that of b.END3 cells or GL261 cells alone, as determined by ELISA assay (Figure 6B). To determine whether Shh secreted from ECs had a significant influence on glioma cells, we generated Shh-knockdown b.END3 cells (siShh-b.END3; see supplementary material, Figure S4D). As shown in Figure 6C, D, both mRNA expression and protein abundance of Gli1 were significantly decreased in GL261 cells co-cultured with siShh-b.END3 cells as compared to wild-type b.END3 cells. Moreover, the expressions of Olig2, Bmi1 and Sox2 (Figure 6D) and the portion of CD133+ GL261 cells (Figure 6E) were also reduced in GL261 cells co-cultured with siShh-b.END3 cells. Furthermore, the size and number of tumour spheres formed by GL261 cells co-cultured with siShh-b.END3 cells were significantly smaller and reduced, respectively (Figure 6F). To examine how Shh in b.END3 cells was up-regulated, we detected CXCR4 and VEGF in our co-culture model. Both CXCR4 and VEGF in co-cultured b.END3 cells (Figure 6G) and SDF1 in co-cultured GL261 cells (Figure 6H) were significantly induced. Treatment with VEGF, but not SDF1 (see supplementary material, Figure S3F), could increase Shh expression in both b.END3 cells and HUVECs (Figure 6I). Thus, our data imply that GL261 cells may stimulate Shh secretion from b.END3 cells, and that Shh secreted from ECs activates the HH pathway to promote a CSC-like phenotype, possibly through the VEGF stimulation.
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.