Sevoflurane promotes the expansion of glioma stem cells through activation of hypoxia-inducible factors in vitro

Background. Growing evidences indicate that inhalational anaesthetics can enhance the growth and malignant potential of tumour cells and may affect tumour recurrence after surgery. Tumour stem cells play a vital role in tumour recurrence. This study investigates the effect of sevoflurane on glioma stem cells (GSCs) in vitro and the underlying molecular mechanisms in this process. Methods. Cultured GSCs were exposed to clinically relevant concentrations and durations of sevoflurane exposure. Cell proliferation and self-renewal capacity were determined. Expression of the stem cell marker CD133, vascular endothelial growth factor (VEGF), hypoxia-inducible factors (HIFs), and phosphorylated Akt, which is a protein kinase invoved in multiple cellular processes, were measured using western blotting. Small interfering RNAs and an Akt inhibitor were used to investigate specific pathways. Results. Compared with controls, cells exposed to 2% sevoflurane for 6 h induced a larger number of proliferated cells (31.2 + 7.6% vs 19.0 + 5.8%; P<0.01). Levels of CD133, VEGF, HIF-1 alpha, HIF-2 alpha, and p-Akt were up-regulated by sevoflurane in a time-and concentration-dependent manner. Small interfering RNA against HIFs decreased the percentage of proliferating GSCs after sevoflurane exposure and pre-treatment of cells with an Akt inhibitor abrogated the expression of HIFs induced by sevoflurane. Conclusions. Sevoflurane can promote the expansion of human GSCs through HIFs in vitro. Inhaled anaesthetics may enhance tumour growth through tumour stem cells.