GSE128207
Meningeal lymphatic vasculature mediates cervical lymph node metastasis of brain tumors through VEGF-C/VEGFR3/eNOS signaling pathway
Purpose: The rediscovery of meningeal lymphatic vessels (MLVs) suggests a potential linkage between brain tumors and cervical lymph nodes (LNs). In this study, we investigated whether and how meningeal lymphatics regulate the metastasis of brain tumor cells. Experimental Design: We first examined the pattern of MLVs and LNs after tumor cells were injected into the cisterna magna (i.c.m.) or subdural space of mice. The meninges were isolated and analyzed by whole-mount immunofluorescence staining. LN metastasis was analyzed by detecting GFP+ tumor cells. Then we used inducible knock-out mice and AAV-VEGF-C delivery system to study the function of MLVs in mediating the metastasis of brain tumor cells. Finally, RNA-seq was used to determine the expression profiles of meningeal lymphatic endothelial cells (mLECs) in mice with or without tumors. The roles of the endothelial nitric oxide synthetase (eNOS) were evaluated both genetically and pharmacologically in vivo. Results: Meningeal lymphangiogenesis induced by GL261 and B16 tumors was correlated with dCLN swelling and metastasis. dCLN metastasis was suppressed in MLV-defective mice, while promoted in AAV-VEGF-C-treated mice. In addition, we found that VEGF-C/VEGFR3 signaling regulated both meningeal and tumor lymphangiogenesis. Tumor-associated mLECs have a distinct transcriptomic signature, which highly express eNOS. Furthermore, genetic or pharmacological inhibition of eNOS significantly suppressed meningeal lymphangiogenesis and dCLN metastasis. Conclusions: The meningeal lymphatic vasculature mediates the metastasis of brain tumors to cervical LNs, mainly through a VEGF-C/VEGFR3-eNOS signaling pathway, suggesting that MLV may be a potential therapeutic target for the extracranial metastasis of brain tumors. Overall design: Here we sequenced meningeal lymphatic endothelial cells from control mice without tumor bearing, GL261 tumor bearing mice and B16 tumor bearing mice. 10 lymphatic endothelial cells were placed into the lysis buffer, n = 3 biological replicates per group. Marker genes were analyzed to be qualified, then differently expressed genes were screened.