Exosome-transmitted ANGPTL1 suppresses angiogenesis in glioblastoma by inhibiting the VEGFA/VEGFR2/Akt/eNOS pathway

J Neuroimmunol. 2024 Feb 15:387:578266. doi: 10.1016/j.jneuroim.2023.578266. Epub 2023 Dec 15.

Abstract

Objective: Glioblastoma (GBM) is a highly vascularized malignancy that relies on new vessel generation, and thus targeting angiogenesis has been a promising anti-GBM approach. ANGPTL1 is well-known for its anti-angiogenic property; nevertheless, its role in GBM is yet to be explored. Recently, the crucial role of exosomes (Exos) as intercellular communication mediators has gained prominence in GBM therapy. This work aimed to explore the role of exosomal ANGPTL1 in GBM angiogenesis and its mechanisms.

Methods: Bioinformatic analysis was performed to evaluate ANGPTL expression in GBM. Human GBM cell lines (U87 and U251) and a xenograft mouse model were employed. Exos were isolated from oe-NC- and oe-ANGPTL-transfected bone mesenchymal stem cells and identified. Cell proliferation, migration, and apoptosis were detected. Immunofluorescence, qRT-PCR, western blotting, co-immunoprecipitation, and immunohistochemistry were used to determine the molecular mechanisms underlying exosomal ANGPTL1 against GBM angiogenesis. Besides, tube generation and transmission electron microscope assays were conducted to assess GBM angiogenesis.

Results: Low ANGPTL1 expression was observed in GBM tumor tissues and cells. Functionally, e-ANGPTL-Exos inhibited GBM malignant progression and angiogenesis in vitro and in vivo. Mechanically, e-ANGPTL-Exos reduced VEGFA expression and blocked the VEGFR2/Akt/eNOS pathway in GBM cells and tumor tissues. Co-immunoprecipitation revealed a link between ANGPTL1 and VEGFA in GBM cells. Notably, oe-VEGFA abolished the suppressive functions of e-ANGPTL-Exos in GBM progression and angiogenesis and the VEGFR2/Akt/eNOS axis. The VEGFR2 inhibitor, vandetanib, eliminated the promotive effects of oe-VEGFA on GBM angiogenesis with suppressed VEGFR2/Akt/eNOS pathway.

Conclusions: Exosomal ANGPTL1 suppressed GBM angiogenesis by inhibiting the VEGFA/VEGFR2/Akt/eNOS axis.

Keywords: Angiogenesis; Angiopoietin-like protein 1; Exosome; Glioblastoma; VEGFA/VEGFR2/Akt/eNOS pathway.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Angiogenesis
  • Angiopoietin-Like Protein 1
  • Animals
  • Cell Line
  • Cell Line, Tumor
  • Cell Proliferation
  • Exosomes* / metabolism
  • Glioblastoma* / metabolism
  • Humans
  • Mice
  • Proto-Oncogene Proteins c-akt / metabolism
  • Vascular Endothelial Growth Factor A

Substances

  • Proto-Oncogene Proteins c-akt
  • VEGFA protein, human
  • Vascular Endothelial Growth Factor A
  • ANGPTL1 protein, human
  • Angiopoietin-Like Protein 1