阿霉素通过激活Notch信号通路促进骨肉瘤细胞干性特性

Doxorubicin induces enrichment of stem-like cells in osteosarcoma by activating Notch signaling

目的:骨肉瘤干细胞具有化疗耐药性。本文拟探讨耐阿霉素细胞干细胞样特性的改变,以及Notch通路在其中的调控作用。方法:采用2μM的阿霉素处理骨肉瘤细胞143B 24 h,去药继续培养5 d,检测干细胞样特性的改变,包括形态学的改变、Stro-1^+/CD117^+双阳性细胞比例、干细胞相关基因表达、悬浮成球的能力、EMT特性。qPCR及Western blot检测Notch通路受体及靶基因表达情况。利用Notch抑制剂DAPT预处理,检测其对耐阿霉素骨肉瘤细胞的干细胞样特性的影响。构建裸鼠移植瘤模型,检测Notch抑制剂对体内成瘤的影响。结果:耐阿霉素骨肉瘤细胞中Stro-1^+/CD117^+比例增高,干细胞相关基因Oct4、Sox2表达量增加,悬浮成球能力增强,EMT特性上调。q PCR及Western blot结果显示阿霉素耐药的骨肉瘤细胞中Notch受体胞内段NICD1及靶基因Hes1、Hey1等表达量上调。Notch信号抑制剂能够增强骨肉瘤对阿霉素的化疗敏感性,抑制体外阿霉素对骨肉瘤干细胞的富集作用。动物实验表明,Notch抑制剂DAPT能够抑制体内成瘤。结论:阿霉素能够富集骨肉瘤干细胞,Notch信号通路参与其中调控机制,抑制Notch通路能够靶向杀伤骨肉瘤细胞,增加化疗药物敏感性。

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.