Abstract 291: A ketogenic diet rewires pancreatic cancer metabolism towards an actionable metabolic
Authors: Hajihassani Omid , Zarei Mehrdad , Loftus Alaxander , Tahan Soubhi , Gallagher Peter , Lebo Kevin , Chang Helen , Moore Elise , Mudigonda Anusha , Hue Jonathan , Graor Hallie , Winter Jordan 
Published: June 2023

Background: A ketogenic regimen is high in fat (90%kCal) and low in carbohydrates (5% kCal), resulting in a state of ketosis[2]. Prior studies suggest that a ketogenic diet shifts carbon utilization in cancer cells from one that is predominantly glycolytic, towards the tricarboxylic acid cycle (TCA) in the mitochondria[3]. The net effect on cancer growth remains uncertain, but the majority of studies in the literature favor an anti-cancer signal. We hypothesize that molecular and biochemical insights into how pancreatic cancer cells adapt to a ketogenic diet will uncover metabolic vulnerabilities and nominate rationally designed therapeutic strategies to effectively partner with the diet.

Methods: A ketogenic diet was administered to mice, along with a normal diet in control mice. Pancreatic cancer xenografts were monitored for growth and harvested for biochemical analyses. Tumors were analyzed for metabolites by LC/GC-MS and for oxidative stress by measuring the levels of NAD+/NADH and Lipid Peroxidation assays. Enzyme expression was assessed by Western blot. For in vitro studies, mitochondrial function was analyzed by the Seahorse FX Analyzer and cell growth was measured by PicoGreen DNA quantitation.

Result: A ketogenic diet slowed pancreatic cancer growth in multiple in vivo models, including MIA-PaCa2, KPC and patient derived xenografts. TCA metabolites were broadly increased in xenografts exposed to a ketogenic diet. In these mouse tumors, metabolic enzymes associated with the TCA cycle were markedly upregulated, pointing to an effect on gene expression. Specifically, the expression of BDH1 (a ketolytic enzyme allowing ketone body utilization in cancer cells), IDH1 (cytosolic and supports antioxidant defense and mitochondria through NADPH and α-ketoglutarate) and IDH2 (a homolog of IDH1 in the mitochondria) were all increased. In contrast, the glycolytic enzyme, G3P, was reduced. 3). additionally, a ketogenic diet induced oxidative stress in pancreatic cancer in vivo. Based on the adaptations observed in pancreatic cancer, we combined a ketogenic diet with an inhibitor of IDH1 to thwart antioxidant defense and impair mitochondrial function. The combination resulted in markedly reduced tumor proliferation, compared to either treatment alone. In vitro studies revealed that low glucose and fatty acids are likely the major drivers of reduced pancreatic cancer cell proliferation with a ketogenic diet, while exogenous ketone bodies are utilized for energy by mitochondria under glucose withdrawal and generally have a pro-tumor effect.

Conclusion: A ketogenic diet has a strong anti-tumor effect in multiple pancreatic cancer mouse models, and the effect is likely a result of the low glucose and increased fatty acid load associated with the diet. Metabolic adaptation towards an OXPHOS phenotype renders pancreatic cancer especially susceptible to antioxidant and mitochondrial inhibitors.

Citation Format: Omid Hajihassani, Mehrdad Zarei, Alaxander Loftus, Soubhi Tahan, Peter Gallagher, Kevin Lebo, Helen Chang, Elise Moore, Anusha Mudigonda, Jonathan Hue, Hallie Graor, Jordan Winter. A ketogenic diet rewires pancreatic cancer metabolism towards an actionable metabolic [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 291.