Abstract 183: N-myc downstream regulated gene 1 (NDRG1) is indispensable for VEGF-A-induced tumor angiogenesis through PLCγ/ERK signaling activation in vascular endothelial cells

Abstract

Abstract [Background] Vascular endothelial growth factor (VEGF)-A is a key regulator of tumor angiogenesis that is essential for tumor growth and progression. The unraveling of the precise mechanisms behind VEGF-A-induced tumor angiogenic process will further contribute to development of novel and potent anti-cancer therapeutics. N-myc downstream regulated gene 1 (NDRG1) has been shown to play essential roles in multiple biological processes including embryogenesis, tissue development, cell growth, differentiation, and tumorigenesis. We previously reported that NDRG1 expression levels in cancer cells are closely correlated with tumor angiogenesis and growth (Hosoi et al., Cancer Res., 2009; Murakami et al., J Biol Chem., 2013), and also that NDRG1 promotes tumor angiogenesis through enhanced VEGF-A production by tumor-associated macrophages (Watari et al., Sci Rep., 2016). However, it remains unclear whether NDRG1 expression in vascular endothelial cells (ECs) plays any crucial role in VEGF-A-induced tumor angiogenesis. In our present study, we further ask whether and how NDRG1 in ECs could specifically regulate tumor angiogenesis. We also present our finding of intrinsic importance that NDRG1 functions as an essential factor for VEGF-A-induced angiogenesis. [Methods] NDRG1 deficient mice: The NDRG1 deficient mice on C57BL6 background were purchased from Laboratory Animal Resource Bank, National Institutes of Biomedical Innovation, Health and Nutrition (Osaka, Japan). Isolation of mouse endothelial cells: CD31+ endothelial cells were isolated from mouse lung by magnetic sorting using CD31 MicroBeads. Aortic ring assay: 1 mm mouse aortic rings were embedded in 3-dimensional growth factor reduced Matrigel, treated with or without FGF-2 (50 ng/mL) or VEGF (25 ng/ml), and incubated at 37°C. Vascular length and branching point were measured at day 7. [Results] [1] Analysis of TCGA datasets revealed that NDRG1 expression was positively correlated with VEGF-A expression in patients with various cancer types. [2] In breast cancer patients in Kurume University hospital, NDRG1 was expressed in both cancer cells and ECs. In NDRG1 deficient mice, we observed following experimental results. [3] Both tumor growth and angiogenesis were all suppressed in syngeneic tumors. [4] VEGF-A-induced angiogenesis was specifically impaired in corneal micropocket assay and aortic ring assay, whereas FGF-2 could induce angiogenesis in both assays. [5] NDRG1 formed a complex with PLC-γ, and this complex formation was requisite for the VEGF-A-induced PLCγ/ERK activation in ECs. [Conclusion] We first present an indispensable role of NDRG1 in VEGF-A-induced angiogenesis through PLCγ/ERK activation in ECs. The NDRG1 could be a novel candidate target for development of therapeutics for VEGF-A-induced tumor angiogenesis and other vascular diseases. Citation Format: Kosuke Watari, Tomohiro Shibata, Ai Shinoda, Hideyuki Abe, Akihiko Kawahara, Yuichi Murakami, Eiji Oki, Jun Akiba, Yoshihiko Maehara, Michihiko Kuwano, Mayumi Ono. N-myc downstream regulated gene 1 (NDRG1) is indispensable for VEGF-A-induced tumor angiogenesis through PLCγ/ERK signaling activation in vascular endothelial cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 183.