Aberrant Notch signaling in glioblastoma stem cells contributes to tumor recurrence and invasion

Upregulation of the Notch signaling pathway in cancer stem cells and side population (SP) cells has a major role in maintenance, self-renewal and chemoresistance. The present study isolated a cancer stem cell-like SP accounting for 4.1% of a glioblastoma cell population using a Hoechst 33342 dye exclusion assay. In this glioblastoma SP, the expression of of Notch1 signaling proteins Notch1 intracellular domain and Hes-1 was markedly upregulated. Furthermore, knockdown of Notch1 by RNA interference significantly diminished the neurosphere formation ability, self-renewal and chemoresistance of the SP cells. In addition, the expression of the stem-cell surface genes Oct-4, Sox2 and Nanog in SP cells was significantly reduced and the sensitivity to the SP cells to chemotherapeutics was enhanced following Notch1 knockdown. In conclusion, the results of the present study suggested that upregulation of Notch1 is involved in the chemotherapy resistance and tumor recurrence of glioblastoma. Hence, the development of novel anti-cancer drugs targeting the Notch1 signaling pathway may be a promising strategy for curing glioblastoma.