Isoflurane suppresses the self-renewal of normal mouse neural stem cells in a p53-dependent manner by activating the Lkb1-p53-p21 signalling pathway

Isoflurane is widely used in anaesthesia for surgical operations. However, whether it elicits unwanted side effects, particularly in neuronal cells, remains to be fully elucidated. The Lkb1-p53-p21 signalling pathway is able to modulate neuronal self-renewal and proliferation. Furthermore, the suppression of Lkb1-dependent p21 induction leads to apoptosis. In the present study, whether Lkb1-p53-p21 signalling is involved in the response to isoflurane was investigated. A comparison of mouse primary, wild-type neural stem cells (WT NSCs) with the p53(−/−) NSC cell line, NE-4C, revealed that isoflurane inhibited proliferation in a dose-, a time- and a p53-dependent manner. However, flow cytometric analysis revealed that the concentration of isoflurane which caused 50% inhibition (the IC(50) value) induced cell cycle arrest in WT NSCs. Furthermore, the protein expression levels of LKB1, p53 and p21 were increased, although those of nestin and survivin decreased, following treatment of WT NSCs with isoflurane. On the other hand, isoflurane induced the phosphorylation of Ser15 in p53 in WT NSCs, which was associated with p53 binding to the p21 promoter, and consequentially, the transcriptional activation of p21. All these events were abrogated in NE-4C cells. Taken together, the present study has demonstrated that isoflurane suppresses the self-renewal of normal mouse NSCs by activating the Lkb1-p53-p21 signalling pathway.