Autophagy-induced KDR/VEGFR-2 activation promotes the formation of vasculogenic mimicry by glioma stem cellsAntiangiogenesis with bevacizumab, an antibody against vascular endothelial growth factor (VEGF), has been used for devascularization to limit the growth of malignant glioma. However, the benefits are transient due to elusive mechanisms underlying resistance to the antiangiogenic therapy. Glioma stem cells (GSCs) are capable of forming vasculogenic mimicry (VM), an alternative microvascular circulation independent of VEGF-driven angiogenesis. Herein, we report that the formation of VM was promoted by bevacizumab-induced macroautophagy/autophagy in GSCs, which was associated with tumor resistance to antiangiogenic therapy. We established a 3-dimensional collagen scaffold to examine the formation of VM and autophagy by GSCs, and found that rapamycin increased the number of VM and enhanced KDR/VEGFR-2 phosphorylation. Treatment with chloroquine, or knockdown of the autophagy gene ATG5, inhibited the formation of VM and KDR phosphorylation in GSCs. Notably, neutralization of GSCs-produced VEGF with bevacizumab failed to recapitulate the effect of chloroquine treatment and ATG5 knockdown, suggesting that autophagy-promoted formation of VM was independent of tumor cell-derived VEGF. ROS was elevated when autophagy was induced in GSCs and activated KDR phosphorylation through the phosphoinositide 3-kinase (PI3K)-AKT pathway. A ROS inhibitor, N-acetylcysteine, abolished KDR phosphorylation and the formation of VM by GSCs. By examination of the specimens from 95 patients with glioblastoma, we found that ATG5 and p-KDR expression was strongly associated with the density of VM in tumors and poor clinical outcome. Our results thus demonstrate a crucial role of autophagy in the formation of VM by GSCs, which may serve as a therapeutic target in drug-resistant glioma.
High‐mobility group box 1 released by autophagic cancer‐associated fibroblasts maintains the stemness of luminal breast cancer cellsXilong Zhao, Yong Lin, Jun Jiang et al.|The Journal of Pathology|2017 Cancer stem cells/cancer-initiating cells (CICs) and their microenvironmental niche play a vital role in malignant tumour recurrence and metastasis. Cancer-associated fibroblasts (CAFs) are major components of the niche of breast cancer-initiating cells (BCICs), and their interactions may profoundly affect breast cancer progression. Autophagy has been considered to be a critical process for CIC maintenance, but whether it is involved in the cross-talk between CAFs and CICs to affect tumourigenesis and pathological significance has not been determined. In this study, we found that the presence of CAFs containing high levels of microtubule-associated protein 1 light chain 3 (LC3II), a marker of autophagosomes, was associated with more aggressive luminal human breast cancer. CAFs in human luminal breast cancer tissues with high autophagy activity enriched BCICs with increased tumourigenicity. Mechanistically, autophagic CAFs released high-mobility group box 1 (HMGB1), which activated its receptor, Toll-like receptor (TLR) 4, expressed by luminal breast cancer cells, to enhance their stemness and tumourigenicity. Furthermore, immunohistochemistry of 180 luminal breast cancers revealed that high LC3II/TLR4 levels predicted an increased relapse rate and a poorer prognosis. Our findings demonstrate that autophagic CAFs play a critical role in promoting the progression of luminal breast cancer through an HMGB1-TLR4 axis, and that both autophagy in CAFs and TLR4 on breast cancer cells constitute potential therapeutic targets. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
A three-dimensional collagen scaffold cell culture system for screening anti-glioma therapeutics// Donglai Lv 1, 2 , Shi-cang Yu 1, 2 , Yi-fang Ping 1, 2 , Haibo Wu 1, 2 , Xilong Zhao 1, 2 , Huarong Zhang 1, 2 , Youhong Cui 1, 2 , Bing Chen 3, 4 , Xia Zhang 1, 2 , Jianwu Dai 3, 4 , Xiu-wu Bian 1, 2, * , Xiao-hong Yao 1, 2, * 1 Institute of Pathology and Southwest Cancer Center, Southwest Hospital, Third Military Medical University, Chongqing, China 2 Key Laboratory of Tumor Immunopathology, Ministry of Education of China, Chongqing, China 3 State Key Laboratory of Trauma, Burns and Combined Injury, Institute of Combined Injury, School of Military Preventive Medicine, Third Military Medical University, Chongqing, China 4 Institute of Genetics and Development, Chinese Academy of Sciences, Beijing, China * These authors have contributed equally to this work Correspondence to: Xiao-hong Yao, email: yxh15@hotmail.com Xiu-wu Bian, email: bianxiuwu@263.net Keywords: chemosensitivity, collagen scaffold, glioma stem cells, three-dimensional culture, MGMT Received: February 27, 2016 Accepted: June 30, 2016 Published: July 28, 2016 ABSTRACT Three-dimensional (3D) culture, which can simulate in vivo microenvironments, has been increasingly used to study tumor cell biology. Since most preclinical anti-glioma drug tests still rely on conventional 2D cell culture, we established a collagen scaffold for 3D glioma cell culture. Glioma cells cultured on these 3D scaffolds showed greater degree of dedifferentiation and quiescence than cells in 2D culture. 3D-cultured cells also exhibited enhanced resistance to chemotherapeutic alkylating agents, with a much higher proportion of glioma stem cells and upregulation of O6-methylguanine DNA methyltransferase (MGMT). Importantly, tumor cells in 3D culture showed chemotherapy resistance patterns similar to those observed in glioma patients. Our results suggest that 3D collagen scaffolds are promising in vitro research platforms for screening new anti-glioma therapeutics.