Abstract 761: Specific inhibition of prostaglandin E2 production in medulloblastoma

Abstract

Abstract Introduction: Prostaglandin E2 (PGE2) is a key lipid mediator of inflammation and carcinogenesis. Apart from promoting direct growth of cancer cells, PGE2 has been shown to be crucial in maintaining the immunosuppressive tumor microenvironment. Drugs targeting cyclooxygenase (COX)-1 and -2, enzymes upstream in the production of PGE2 and other prostanoids, have successfully reduced tumor growth in many cancer models but these drugs are all associated with adverse long-term effects. The aim of this study is to demonstrate an anti-tumor effect in medulloblastoma by selective inhibition of microsomal prostaglandin E1 (mPGES-1), the enzyme downstream of COX-1/2 specifically required for the synthesis of PGE2. Experimental procedures: Human medulloblastoma cell lines (DAOY and D283) were treated with a selective small-molecule inhibitor against mPGES-1 or COX-2 in the presence or absence of pro-inflammatory interleukin (IL)-1â. Prostaglandins in supernatants were extracted and quantified with LC-MS/MS. Drug efficacy was determined and cell toxicity was measured with cell viability assay. Mice with human medulloblastoma xenograft will function as proof-of-concept for the anti-tumor activities associated with inhibition of PGE2 production. Key inflammatory enzymes were quantified with Western blot. Results: Medulloblastoma cells express high levels of COX-2, mPGES-1, and produce PGE2. The increased production of PGE2 by IL-1â was completely blocked when cells were co-treated with inhibitor for mPGES-1 or COX-2. Both inhibitors showed cell toxicity. We did not observe any shunting towards other prostanoids. Conclusion: We investigate the effect of selective inhibition of mPGES-1 or COX-2 on medulloblastoma growth. We aim to further characterize the mPGES-1 inhibitor and compare to selective COX-2 inhibitor in preclinical medulloblastoma models. Specific inhibition of PGE2 production, rather than general inhibition of prostanoid production, would potentially prove useful as a complement to current medulloblastoma treatments. Citation Format: Filip Bergqvist, Linda Ljungblad, Malin Wickström, Karin Larsson, Anna Kock, Marina Korotkova, John Inge Johnsen, Per Kogner, Per-Johan Jakobsson. Specific inhibition of prostaglandin E2 production in medulloblastoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 761.