Abstract 5711: Targeting FTO suppresses pancreatic carcinogenesis via cancer stem cell maintenance
Authors: Garg Rachana , Melstorm Laleh , Chen Jianjun , He Chuan , Goel Ajay 
Published: June 2022

Background: Pancreatic cancer (PC) remains a lethal disease worldwide and is estimated to become the 2nd leading cause of cancer-related deaths in the United States by 2030. Recently, existence of cancer stem cells (CSC) has been reported in several malignancies, including PC and have been considered as seeds for cancer initiating cells. However, the molecular mechanism governing the maintenance of CSC traits and their self-renewal remain unclear. Upregulated expression of fat mass and obesity-associated protein (FTO), which demethylates N6-methyladenosine (the most prevalent eukaryotic RNA modification), has been associated with cancer progression of various types. Nevertheless, our current understanding on the role of FTO in modulating biological processes relevant to PC is in infancy.

Methods: In this study, we first analyzed and compared the FTO expression in various PC cells vs normal pancreatic ductal epithelial (HPDE) cells. We then depleted FTO in PC cells using lentiviral-mediated and pharmacological inhibitor (CS1) approaches and analyzed the effects on cell growth, proliferation, apoptosis, cell cycle, migration, invasion, epithelial-mesenchymal transition, CSC growth and self-renewal, and xenograft tumor formation.

Results: We found that PC cells expressed markedly higher mRNA and protein levels of FTO compared to HPDE cells. FTO depleted PC cells showed impaired growth in both the solid and semi-solid medium, and also a G1 phase cell cycle arrest which correlated with the increment in the expression of CDK inhibitors: p21cip1 and p27kip1. FTO loss in the PC cells also led to an increase in early apoptotic cell population with a concomitant increase in the expression of caspase 3 and 9. Of note, FTO depleted PC cells displayed marked delay in the wound closure and reduced capabilities to invade through matrigel. This further corroborated with the enhanced expression levels of epithelial (E-cadherin) and decrease in the mesenchymal (N-cadherin, vimentin, and fibronectin) markers. Mechanistically, MET in FTO depleted cells correlated with impaired tumor sphere formation and reduced expression of markers of cancer stemness (CD44, NanoG, Sox2, ALDH1, and CD133). Replating of single cell derived from these spheroids revealed that FTO loss hampered the secondary spheres formation; thus, FTO is necessary for spheroid formation, their maintenance and self-renewal potential of CSC. Additionally, FTO loss in PC cells led to delayed as well as decreased tumor growth in nude mice. Tumor extracts from FTO-depleted xenografts displayed induction of apoptosis, decreased expression of proliferation marker Ki67, and a MET phenotype.

Conclusion: Through a comprehensive mechanistic analysis we explicitly demonstrate the biological and functional significance of FTO in governing PC tumorigenesis and maintenance of CSC; thus, targeting FTO may represent an attractive therapeutic approach for PC.

Citation Format: Rachana Garg, Laleh Melstorm, Jianjun Chen, Chuan He, Ajay Goel. Targeting FTO suppresses pancreatic carcinogenesis via cancer stem cell maintenance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5711.