Doxorubicin induces enrichment of stem-like cells in osteosarcoma by activating Notch signaling / 中国肿瘤临床

ABSTRACT

Objective:Cancer stem cells (CSCs) are resistant to chemotherapy. Our study aimed to investigate the stem cell-like proper-ties of doxorubicin-resistant osteosarcoma cell line 143B and its correlation with Notch signaling. Methods:We generated doxorubicin-resistant osteosarcoma cells by treating them with 2μm doxorubicin. Stem cell-like properties such as morphology change, Stro-1/CD117 double positive ratio, stem cell-related gene expression, sphere formation efficiency, and EMT character were assessed on day 5 after doxorubicin withdrawal. Notch receptor and its target genes were examined using qPCR and Western blot analysis. The stem cell-like properties of doxorubicin-resistant osteosarcoma cells were assessed when pretreated with Notch inhibitor or vehicle. The an-ti-tumor effect of Notch inhibitor was tested using a xenograft model. Results:Doxorubicin-resistant osteosarcoma cells were enriched in Stro-1+/CD117+cells, which showed obvious increased expression of stem cell-related genes, and exhibited enhanced spheroid for-mation and evident mesenchymal characteristics unlike doxorubicin-sensitive cells. qPCR and Western blot assays showed that Notch intracellular domain 1 (NICD1) and target genes Hes1 and Hey1 were upregulated in doxorubicin-resistant osteosarcoma stem cells compared with those in vehicle cells. Furthermore, pretreatment with a γ-secretase inhibitor (GSI) to prevent Notch signaling en-hanced chemo-sensitivity and inhibited doxorubicin-enriched osteosarcoma stem cell activity in vitro. Finally, the Notch inhibitor pre-vented tumor growth in mice xenograft models. Conclusion: Doxorubicin induced the enrichment of osteosarcoma stem-like cells through Notch signaling, and inactivation of Notch could be useful for overcoming drug resistance and eliminating osteosarcoma.