Vasohibin 2 Promotes Lymphangiogenesis of Lung Squamous Cell Carcinoma Through Snail-dependent VEGF-D Signaling Pathway

Abstract Backgroumd: Tumor metastasis is a process in which tumor cells enter the lymphatic vessels and blood vessels and then spread to the secondary site where they form secondary tumors. In vascular biology, angiogenesis and anti-angiogenesis therapy have been extensively studied, however, the molecular mechanisms involved in lymphangiogenesis and lymphatic metastasis remain unclear.Methods: We analyzed 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 screen the most differentially expressed genes related to the poor prognosis of LUSC patients and validated in an independent Chinese LUSC cohort. We focused on Vasohibin 2 (VASH2) and investigated its biological functions in LUSC proliferation, apoptosis, migration, invasion, as well as lymphangiogenesis by forced over-expressing VASH2 in LUSC cell line H520 in vitro. We also investigated the anti-tumor efficacy of VASH2 target treatment in LUSC xenograft-bearing mice models.Results: We identified 12 genes closely related to poor prognosis of LUSC patients, among which VASH2 was validated in an independent Chinese LUSC cohort and displayed high potential of lymphatic metastasis. VASH2 promoted the proliferation and invasion of LUSC cells both in vitro and vivo. Forced over-expression of VASH2 in LUSC cells promoted the amplification and tube-formation of human umbilical vein endothelial cells (HUVECs) and human lymphatic endothelial cells (HLECs) cells via up-regulating vascular endothelial growth factor-D (VEGF-D) production which could be reversed by Snail inhibition. Furthermore, blocking VASH2/VEGF-D signaling using specific antibodies dramatically inhibited tumor growth in mice by interfering proliferation of cancer cells and lymphangiogenesis in tumor tissues. Conclusion: In conclusion, VASH2 facilitated lymphangiogenesis and tumor growth in a Snail-dependent manner which might serve as a novel biomarker for early diagnosis and prognosis prediction, as well as a potential therapeutic target in LUSC.Statement of conflict of interest: The authors declare no potential conflicts of interest.