Culture of glioblastoma U87 stem-like cells and identification of its metabolic phenotype and tumorigenic ability

Abstract

Objective To cultivate glioblastoma U87 stem-like cells (SLCs) and to detect the level of stemness biomarkers, mitochondrial respiratory capacity and the capacity of in vivo tumorigenesis. Methods B-27, growth factors EGF and bFGF was added into DMEM/F-12 culture in serum-free stem cell culture medium for U87 SLCs. Suspended culture of U87 SLCs was suspended using the neuro-sphere formation assay, while adherent culture of U87 SLCs was achieved by coating Matrigel matrix on the culture surface. The mRNA and protein level of stemness biomarkers in culture were detected using real-time quantitative PCR and Western blot. The proportion of CD133+ cells in culture was detected by flow cytometry. The changes of cell oxygen consumption rate were detected by Seahorse cell metabolism analysis. Cell tumorigenesis ability was verified by subcutaneous tumor transplantation in animals. Results U87 SLCs in stem cell culture medium would grow into typical sphere morphology within one week, and the spheres would continue to grow as the culture process prolongs. At the appropriate concentration of adhesive, U87 SLCs adhered to and grow well in stem cell culture medium. The mRNA transcription of stemness biomarkers such as CD133, nestin, OLIG2, CD44, CD15, and integrin α6(ITGA6) was significantly increased as found in both culture methods, and the protein levels of CD133 and nestin were also increased under both methods(P＜0.05). U87 SLCs showed higher mitochondrial reserve respiratory capacity (P＜0.05). U87 SLCs could form larger subcutaneous tumors with fewer inoculated cells (P＜0.05), and grew faster in vivo with stronger tumorigenic ability. Conclusions U87 SLCs have typical stemness characteristics and may function as tumor cell model with higher stemness properties.

Keywords

• glioblastoma|stem-like cell|neuro-sphere|stemness