Abstract 4884: Determination of sphingosine-1-phosphate levels in tissue interstitial fluid and lymphatic fluid utilizing novel collection techniques

Abstract Sphingosine-1-phosphate (S1P) is a pleiotropic bioactive lipid mediator that regulates many processes of cancer progression including angiogenesis. Among the two sphingosine kinases (SphK1 and SphK2), S1P generated by SphK1 inside cells is secreted and exerts its functions by binding to specific G protein-coupled receptors outside the cells. It is known that S1P levels in circulation of SphK1-/- mice are low and SphK2 -/- mice are high compared from controls. Utilizing SphK2 -/- mice, we have recently reported that S1P links inflammation and cancer in colitis-associated colon cancer. Further, we have shown that secreted S1P plays critical roles in tumor microenvironment by stimulating both angiogenesis and lymphangiogenesis. Although it is well established that S1P plays important roles in lymphatic fluid and interstitial fluid (IF), no methodology has been available to date to measure S1P levels in those fluid. Here we introduce for the first time the newly developed methods and measurements of levels of sphingolipids including S1P in IF and lymphatic fluid in both SphK1 -/- and SphK2 -/- mice. We found that S1P levels in the lymphatic fluid and IF are generally low in SphK1-/- mice and high in SphK2-/- mice. Interestingly, however, S1P levels in IF of the colon in SphK2-/- mice are significantly lower compared with wild type mice, where levels in downstream mesenteric lymph nodes and lymphatic fluid are higher, which is in agreement with the previous notion that lymphatic endothelial cells contribute to the S1P levels in the lymphatic fluid. Measurement of sphingolipids in IF and lymphatic fluid will provide new insights into mechanism of their actions in lymphatic progression of cancer. M.N. is a Japan Society for the Promotion of Science Postdoctoral Fellow. S.S. is supported by NIH R37GM043880, and K.T. by NIH R01CA160688 and Susan G. Komen IIR 1222224. Citation Format: Masayuki Nagahashi, Akimitsu Yamada, Hiroshi Miyazaki, Jeremy C. Allegood, Tomoyoshi Aoyagi, Wei-Ching Huang, Krista P. Terracina, Sheldon Milstien, Sarah Spiegel, Kazuaki Takabe. Determination of sphingosine-1-phosphate levels in tissue interstitial fluid and lymphatic fluid utilizing novel collection techniques. [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 4884. doi:10.1158/1538-7445.AM2014-4884