Abstract 1585: Targeting acid ceramidase-1 to inhibit sphingolipid metabolism and tumor growth in pancreatic ductal carcinoma
Authors: Jain Krishan G. , Ghosh Hindole , Bhattacharyya Sangita , Kasi Anup , Hamza Ameer , Weir Scott J. , VanSaun Michael , Bossmann Stefan , Anant Shrikant , Biersack Bernhard , Dandawate Prasad R. 
Published: June 2023

Abstract
Pancreatic ductal adenocarcinoma (PDAC) is a leading cause of cancer-related deaths in the United States. PDAC is an aggressive disease with a poor survival rate of &lt;10%. Hence, there is an urgent need to find novel drug targets for the clinical management of PDAC. Altered sphingolipid metabolism (SM) is a hallmark of cancer. The major sphingolipid metabolites are ceramide, sphingosine and sphingosine-1-phosphate (S1P). We found that S1P is the predominant SM metabolite in PDAC cells and tissues. The equilibrium between ceramide and S1P levels within the body is an important factor to determine cell fate. Ceramide induces apoptosis, while S1P promotes cancer growth. The IHC and ELISA assays showed that S1P levels are higher in PDAC cells and tissues compared to normal pancreatic tissue. We found that S1P induces spheroid formation in PDAC cells at nanomolar concentrations when compared to C1P and sphingosine. S1P binds to S1P receptors (SIPR1-5) to activate downstream signaling. Mechanistically, S1P treatment activates beta-catenin and notch signaling pathway proteins in PDAC cells. Our data suggest that S1P promotes tumor growth and stemness in PDAC and inhibition of S1P production can be a novel strategy for PDAC treatment. The cancer genome atlas (TCGA) data analysis indicated that genes involved in S1P production, especially acid ceramidase (ASAH1) and sphingosine kinase 1 (SPHK1) are upregulated in PDAC. ASAH1 converts ceramide to sphingosine which further gets converted to S1P by SPHK1. SPHK1 has been targeted in cancers, but kinase inhibitors are traditionally known for their non-selectivity and toxicity. Moreover, selective targeting of S1PR1-5 has been unsuccessful. Hence, there is a need to identify other targets to inhibit the production of S1P. Therefore, we decided to target Acid ceramidase 1 (ASAH1). Inhibiting ASAH1 will result in the accumulation of proapoptotic ceramide and inhibition of S1P production. Our data showed that ASAH1 is overexpressed in PDAC tissue and cells, while the ASAH1 knockdown in PDAC cells resulted in reduced proliferation, colony formation, migration and spheroid formation. Hence, targeting ASAH1 represents a novel strategy to inhibit PDAC progression by inhibiting sphingolipid metabolism and S1P production. Next, we developed a series of ASAH1 inhibitors based on Cerenib-2 (known ASAH1 inhibitor). One of the analogs, Cer-IVA inhibited the proliferation, colony and spheroid formation in PDAC cells at nanomolar concentration. Moreover, it also induced apoptosis and G2/M-cell cycle arrest in a dose and time-dependent manner. Further, it inhibited S1P production and increased ceramide production in PDAC cells. We are currently investigating the antitumor effects of Cer-IVA in an orthotopic model in C57BL/6 mice. In conclusion, targeting ASAH1 by Cer-IVA is an attractive strategy to inhibit S1P production, growth and stemness in PDAC cells.
Citation Format: Krishan G. Jain, Hindole Ghosh, Sangita Bhattacharyya, Anup Kasi, Ameer Hamza, Scott J. Weir, Michael VanSaun, Stefan Bossmann, Shrikant Anant, Bernhard Biersack, Prasad R. Dandawate. Targeting acid ceramidase-1 to inhibit sphingolipid metabolism and tumor growth in pancreatic ductal carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1585.