Abstract 22: Interferon-γ produced by tumor-infiltrating NK cells and CD4+ T cells downregulates TNFSF15 expression in endothelial cells

Abstract

Abstract Endothelial cells in an established vasculature secrete tumor necrosis factor superfamily-15 (TNFSF15; VEGI; TL1A) that functions as a negative modulator of neovascularization to maintain blood vessel stability. TNFSF15 gene expression diminishes at angiogenesis and inflammation sites such as in cancers and wounds. Interferon-γ (IFNγ) is a pleiotropic cytokine expressed primarily by lymphocytes of T cell and NK cell lineages. IFNγ may mediate anti-tumor effects either directly on cancer cell growth or indirectly through immunomodulatory and antiangiogenic responses. However, it was also reported that IFNγ promotes angiogenesis under certain circumstances. Here we show that IFNγ suppresses TNFSF15 expression in human umbilical cord vein endothelial cells (HUVEC). This activity is mediated by IFNγ receptor and the transcription factor STAT1. Since tumor-infiltrating NK and CD4+ T cells are the main sources of IFNγ in tumor lesions, we isolated these cells from peripheral blood of healthy individuals, treated the cells with ovarian cancer OVCAR3 cell-conditioned media, and found a 1- and 10-fold increase of IFNγ production in NK and CD4+ T cells, respectively, compared with that in vehicle-treated cells. These findings support the view that tumor-infiltrating NK and CD4+ T cells under the influence of cancer cells significantly increase the production of IFNγ, which in turn inhibits TNFSF15 expression in tumor vascular endothelial cells, shifting the balance of pro- and anti-angiogenic factors toward escalated angiogenesis potential in the tumor. Citation Format: Xin Gu, Tao Cheng, Luyuan Li. Interferon-γ produced by tumor-infiltrating NK cells and CD4+ T cells downregulates TNFSF15 expression in endothelial cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 22. doi:10.1158/1538-7445.AM2014-22