ANGPTL2-containing small extracellular vesicles from vascular endothelial cells accelerate leukemia progression
Dan Huang, … , Junke Zheng, Tao Cheng
Dan Huang, … , Junke Zheng, Tao Cheng
Published October 27, 2020
Citation Information: J Clin Invest. 2021;131(1):e138986. https://doi.org/10.1172/JCI138986.
View: Text | PDF
Research Article Hematology Stem cells

ANGPTL2-containing small extracellular vesicles from vascular endothelial cells accelerate leukemia progression

Abstract

Small extracellular vesicles (SEVs) are functional messengers of certain cellular niches that permit noncontact cell communications. Whether niche-specific SEVs fulfill this role in cancer is unclear. Here, we used 7 cell type–specific mouse Cre lines to conditionally knock out Vps33b in Cdh5+ or Tie2+ endothelial cells (ECs), Lepr+ BM perivascular cells, Osx+ osteoprogenitor cells, Pf4+ megakaryocytes, and Tcf21+ spleen stromal cells. We then examined the effects of reduced SEV secretion on progression of MLL-AF9–induced acute myeloid leukemia (AML), as well as normal hematopoiesis. Blocking SEV secretion from ECs, but not perivascular cells, megakaryocytes, or spleen stromal cells, markedly delayed the leukemia progression. Notably, reducing SEV production from ECs had no effect on normal hematopoiesis. Protein analysis showed that EC-derived SEVs contained a high level of ANGPTL2, which accelerated leukemia progression via binding to the LILRB2 receptor. Moreover, ANGPTL2-SEVs released from ECs were governed by VPS33B. Importantly, ANGPTL2-SEVs were also required for primary human AML cell maintenance. These findings demonstrate a role of niche-specific SEVs in cancer development and suggest targeting of ANGPTL2-SEVs from ECs as a potential strategy to interfere with certain types of AML.

Authors

Dan Huang, Guohuan Sun, Xiaoxin Hao, Xiaoxiao He, Zhaofeng Zheng, Chiqi Chen, Zhuo Yu, Li Xie, Shihui Ma, Ligen Liu, Bo O. Zhou, Hui Cheng, Junke Zheng, Tao Cheng

×

Figure 8

ANGPTL2-SEVs bind to LILRB2.

Options: View larger image (or click on image) Download as PowerPoint
ANGPTL2-SEVs bind to LILRB2. (A) Immunoelectron microscopy showing the l...
(A) Immunoelectron microscopy showing the location of ANGPTL2 protein in SEVs. Scale bars: 100 nm. (B) Flow cytometry (left) and histogram (right) analysis of ANGPTL2-SEVs binding to LILRB2-chimeric reporter cells. In this experiment, LILRB2-chimeric reporter cells will express GFP when ANGPTL2-SEVs bind to LILRB2 on the cell surface (n = 3; the data represent the means ± SD; **P < 0.01, Student’s t test). The stable chimeric receptor reporter cell system has been previously described (49). The extracellular domain of LILRB2 was chimerically fused with the intracellular domain of paired immunoglobulin-like receptor (PILR). Upon binding with ANGPTL2-SEVs, the receptor can further recruit the adaptor DAP-12 to activate the NFAT promoter, followed by the increase in GFP expression in reporter cells. (C) Colony-forming ability of Pirb+/+ and Pirb–/– AML cells cocultured with control- or ANGPTL2-SEVs (10 μg per 50,000 AML cells) (n = 3; the data represent the means ± SD; *P < 0.05, **P < 0.01, ***P < 0.001, 1-way ANOVA followed by Dunnett’s test). (D) The percentage of AML cells in the PB of recipients injected with Pirb+/+ and Pirb–/– AML cells cocultured with control- or ANGPTL2-SEVs (n = 5; the data represent the means ± SD; *P < 0.05, ***P < 0.001, 1-way ANOVA followed by Dunnett’s test). (E) Survival curves of recipients injected with Pirb+/+ and Pirb–/– AML cells cocultured with control- or ANGPTL2-SEVs (n = 5; **P < 0.01, ***P < 0.001, log-rank test). Experiments were conducted 2–4 times for validation.