Vasohibin 2 promotes lymphangiogenesis of lung squamous cell carcinoma through snail-dependent vascular endothelial growth factor-D (VEGF-D) signaling pathway

BACKGROUND: Tumor lymphatic metastasis is mostly dependent on lymphangiogenesis, which was less studied compared to angiogenesis and the molecular mechanisms involved remained unclear. METHODS: We analyzed the mRNA expression profiles of 937 primary lung squamous cell carcinoma (LUSC) samples from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases to explore the genes related to lymphatic metastasis in LUSC. We focused on vasohibin 2 (VASH2) and investigated its biological functions in LUSC proliferation, apoptosis, migration, invasion, as well as lymphangiogenesis capacity by forced over-expressing VASH2 in LUSC cell line H520 in vitro and in vivo. We also evaluated the anti-tumor efficacy of specific anti-VASH2 antibody in LUSC xenograft-bearing mice models. RESULTS: Vasohibin2 (VASH2) was filtered out as a significant predictive factor of poor prognosis and lymphatic metastasis in LUSC patients both in public datasets and an independent Chinese LUSC cohort. VASH2 promoted the proliferation and invasion of LUSC cells in vitro and vivo. Forced over-expression of VASH2 in LUSC cells promoted the amplification and tube formation capacity of human umbilical vein endothelial cells (HUVECs) and human lymphatic endothelial cells (HLECs) via up-regulating vascular endothelial growth factor-D (VEGF-D), which could be reversed via Snail inhibition. Furthermore, blocking VASH2/VEGF-D signaling using specific antibodies dramatically inhibited tumor growth in mice by interfering with the proliferation of cancer cells and lymphangiogenesis in tumor tissues. CONCLUSIONS: In conclusion, VASH2 facilitated lymphangiogenesis and tumor growth in a Snail-dependent manner and might serve as a novel biomarker for early diagnosis and prognosis prediction, as well as a potential therapeutic target in LUSC.