Tumor-associated microglia/macrophages enhance the invasion of glioma stem-like cells via TGF-β1 signaling pathway.
The invasion of malignant glioma cells into the surrounding normal brain tissues is crucial for causing the poor outcome of this tumor type. Recent studies suggest that glioma stem-like cells (GSLCs) mediate tumor invasion. However, it is not clear whether microenvironment factors, such as tumor-associated microglia/macrophages (TAM/Ms), also play important roles in promoting GSLC invasion. In this study, we found that in primary human gliomas and orthotopical transplanted syngeneic glioma, the number of TAM/Ms at the invasive front was correlated with the presence of CD133(+) GSLCs, and these TAM/Ms produced high levels of TGF-β1. CD133(+) GSLCs isolated from murine transplanted gliomas exhibited higher invasive potential after being cocultured with TAM/Ms, and the invasiveness was inhibited by neutralization of TGF-β1. We also found that human glioma-derived CD133(+) GSLCs became more invasive upon treatment with TGF-β1. In addition, compared with CD133(-) committed tumor cells, CD133(+) GSLCs expressed higher levels of type II TGF-β receptor (TGFBR2) mRNA and protein, and downregulation of TGFBR2 with short hairpin RNA inhibited the invasiveness of GSLCs. Mechanism studies revealed that TGF-β1 released by TAM/Ms promoted the expression of MMP-9 by GSLCs, and TGFBR2 knockdown reduced the invasiveness of these cells in vivo. These results demonstrate that TAM/Ms enhance the invasiveness of CD133(+) GSLCs via the release of TGF-β1, which increases the production of MMP-9 by GSLCs. Therefore, the TGF-β1 signaling pathway is a potential therapeutic target for limiting the invasiveness of GSLCs.
Key Laboratory of Tumor Immunopathology, Third Military Medical University, Ministry of Education of China, Chongqing 400038, China.
Xian-zong
XZ
Ye
Sen-lin
SL
Xu
Yan-hong
YH
Xin
Shi-cang
SC
Yu
Yi-fang
YF
Ping
Lu
L
Chen
Hua-liang
HL
Xiao
Bin
B
Wang
Liang
L
Yi
Qing-liang
QL
Wang
Xue-feng
XF
Jiang
Lang
L
Yang
Peng
P
Zhang
Cheng
C
Qian
You-hong
YH
Cui
Xia
X
Zhang
Xiu-wu
XW
Bian
D000818:Animals; D002450:Cell Communication / Q000276:immunology; D045744:Cell Line, Tumor; D018920:Coculture Techniques; D005910:Glioma / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007958:Leukocyte Count; D008264:Macrophages / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D017628:Microglia / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D009368:Neoplasm Transplantation / Q000276:immunology / Q000473:pathology; D014411:Neoplastic Stem Cells / Q000276:immunology* / Q000473:pathology; D015398:Signal Transduction / Q000276:immunology*; D053773:Transforming Growth Factor beta1 / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000502:physiology*; D015854:Up-Regulation / Q000276:immunology*
C508960:TGFB1 protein, human; C508961:Tgfb1 protein, mouse; D053773:Transforming Growth Factor beta1