Abstract 13: Anti-angiogenic action of leukotriene-C4induced 15-hydroxyprostaglandin dehydrogenase in colon cancer cells is a TNF-α dependent phenomenon

Colorectal cancer (CRC) is one of the leading causes of cancer-related deaths worldwide. Cyclooxygenase-2 (COX-2), which plays a key role in the biosynthesis of prostaglandin E2 (PGE2), is often up-regulated in CRC and in other types of cancer. PGE2 induces angiogenesis and tumor cell survival, proliferation and migration. The tumor suppressor 15-hydroxyprostaglandin dehydrogenase (15-PGDH) is a key enzyme in PGE2 catabolism, converting it into its inactive metabolite 15-keto-PGE2 and is often down-regulated in cancer. Interesting enough, CRC patients expressing high levels of Cysteinyl leukotriene receptor 2 (CysLTR2) have a good prognosis and therefore, we investigated a potential link between CysLTR2-signaling and the tumor suppressor 15-PGDH in colon cancer cells. TNF-α is considered as the main regulators of COX-2 and mPGES-1 that contribute to the increased synthesis of PGE2, which is inhibited by overexpressed 15-PGDH. Level of the pro-tumorigenic PGE2 are increased in CRC, previously attributed to increased production via TNF-α mediated COX-2 up-regulation but more recently attributed to decreased catabolism due to down-regulation of 15-PGDH. Elevation of 15-PGDH expression by leukotriene C4 (LTC4), a CysLTR2 ligand, exhibited anti-tumor activity in colon cancer cells with significant phosphorylation of β-catenin and down-regulation of anti-apoptotic marker Bcl-2 with concurrent activation of CASPASE-3 expression. We also observed a dramatic down-regulation of TNF-α on mRNA level and NF-κβ on both mRNA as well as protein level with LTC4 induced 15-PGDH in a TNF-α dependent manner. Moreover, TNF-α regulated anti-angiogenic action of 15-PGDH in HT-29 and Caco-2 colon cancer cells by depleting the mRNA level of MMP-2 and MMP-9 and protein level of VEGFR-1. Furthermore, our preliminary observation also suggested disrupted tube formation in HUVEC with LTC4 induced 15-PGDH which is mediated by TNF-α. Hence, restoration of 15-PGDH expression through CysLTR2-signaling promotes the anti-angiogenic action against colon cancer cells, indicating an anti-tumor as well as the anti-metastatic efficacy of CysLTR2-signaling. Citation Format: Shakti R. Satapathy, Anita Sjölander. Anti-angiogenic action of leukotriene-C4induced 15-hydroxyprostaglandin dehydrogenase in colon cancer cells is a TNF-α dependent phenomenon [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR;