Abstract 4397: Alpha-Ketoglutarate is a master regulator of epigenetic reprogramming in pancreatic ductal adenocarcinoma progression
Authors: Sherman Kenna , Cheng Jiaqi , Zhou Weiqiang , Ji Hongkai , Maeda Masahiro , Feinberg Andrew P. 
Published: March 2024

Abstract
Most cases of Pancreatic Ductal Adenocarcinoma (PDAC) are diagnosed after metastasis has occurred, making it crucial to find effective treatments for late-stage disease. Previously, our group found widespread epigenetic reprogramming during PDAC metastasis in the absence of additional driver mutations. These cells develop dependence on glucose metabolism through the oxidative pentose phosphate pathway (oxPPP). Inhibition of oxPPP with 6-aminonicotinamide (6AN) reverses the chromatin changes and restores cells to a less malignant state (McDonald et al. Nat Gen, 2017). To identify a clinically actionable mechanism for restoration, we hypothesized that oxPPP dependence leads to downstream metabolic changes that mediate chromatin state. Using untargeted metabolomic analysis, we found that alpha-ketoglutarate (AKG), a cofactor of lysine and histone demethylases, was downregulated by oxPPP inhibition (p=0.033) in a patient-derived xenograft lung metastasis cell line, A13Lg. Treatment of cells with 6AN and a cell permeable precursor of AKG largely reversed the chromatin changes seen on a western blot. Given that AKG is mainly produced by glutamine metabolism, we inhibited glutaminolysis with glutamine deprivation (Gln(-)) or the glutamine antagonist JHU083. Both treatments decreased AKG (Gln(-) p=0.002, JHU083 p=0.038) and prevented cell growth (Gln(-) p&lt;0.0001, JHU083 p=0.0002). Glutamine-deprived cells showed decreased ability to form colonies (p=0.004), and JHU083 treated cells showed impaired migration in a Boyden chamber assay (p=0.003). Western blots showed a decrease in H3K27 acetylation, a marker of euchromatin, and an increase in H3K9 and H3K27 methylation, markers of heterochromatin, in response to both treatments. Further, homogenized time-resolved fluorescence (HTRF) assays on glutamine-deprived cells showed that H3K9 di- (p=0.0016,) and tri- (p=0.0003) methylation was increased. Adding cell permeable AKG to media without glutamine largely negated both the phenotypic and epigenetic changes. Using CUT&RUN against H3K27Ac, we found that acetylation was depleted at promoters involved in tumor cell proliferation, invasion, and migration. Bulk RNA-sequencing also showed decreased expression of genes involved in these pathways. Epigenetic and phenotypic changes were not as apparent after treatment with CB839, a glutaminase 1 inhibitor, suggesting that broad inhibition of glutamine metabolism is necessary for chromatin restoration. Together, these data suggest that decreasing AKG in PDAC distant metastasis cells, through glutamine deprivation or JHU083, leads to chromatin changes that specify less malignant phenotypes, providing a rationale for targeting glutamine metabolism as a therapy for late-stage PDAC. *APF and MM are co-corresponding authors.
Citation Format: Kenna Sherman, Jiaqi Cheng, Weiqiang Zhou, Hongkai Ji, Masahiro Maeda, Andrew P. Feinberg. Alpha-Ketoglutarate is a master regulator of epigenetic reprogramming in pancreatic ductal adenocarcinoma progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4397.