Abstract 1794: PAF1 reprograms metabolism in pancreatic cancer by interacting with HIF1α
Authors: Ogunleye Ayoola O. , Gayen Neelanjana , Marimuthu Saravanakumar , Nimmakayala Rama Krishna , Rauth Sanchita , Alsafwani Zahraa , Cox Jesse L. , Batra Surinder K. , Ponnusamy Moorthy P. 
Published: March 2024

Background: Reprogrammed cellular metabolism has been refocused on in the past decade, as many cancer cells rewire various metabolic pathways to facilitate their survival, unlimited cell growth, and division. RNA Polymerase II-Associated Factor 1 (PAF1)/Pancreatic Differentiation 2 (PD2) is a core subunit of the human PAF1 Complex (PAF1C) that regulates the RNA polymerase II function during transcriptional elongation in normal cells; however, its overexpression has been implicated in promoting pancreatic tumorigenesis and metastasis through epigenetic regulation, chemoresistance, radioresistance and maintenance of cancer stem cells. While most of these studies have provided evidence of the multifunctional nature of PAF1/PD2 in PDAC progression, no study has investigated the role of PAF1/PD2 during the metabolic rewiring of cancer.

Methods: In this study, we sought to examine the role of PAF1/PD2 in the metabolic rewiring of cancer cells in pancreatic ductal adenocarcinoma (PDAC) and decipher how PAF1/PD2 mediates this metabolic reprogramming in PDAC. Pancreatic cancer cell lines were transfected with shRNAs to knock down PAF1/PD2. Metabolic genes regulated by PAF1/PD2 were identified by qPCR and western blot upon PAF1/PD2 depletion. Metabolic assays were performed to investigate the role of PAF1/PD2. Immunoprecipitations identified proteins that interact with PAF1/PD2. Confocal microscopy confirmed the co-localization of PAF1/PD2 with its protein partners. We performed chromatin immunoprecipitation (ChIP) - Polymerase chain reaction to confirm the binding of the PAF1 sub-complex to its target gene.

Results: Our results showed that pancreatic cancer cells depleted PAF1/PD2 downregulate genes involved in aerobic glycolysis compared to control cells. Also, the lactate release assay indicated that more lactate was produced in control cells than in cells with PAF1/PD2 knockdown. Interestingly, we identified that HIF1α interacts with PAF1, specifically in pancreatic cancer cells. PAF1 and HIF1α co-localization was observed in pancreatic cancer cell lines. We also observed that the PAF1/PD2- HIF1α complex bound to the promoter region of LDHA to regulate the expression of LDHA in pancreatic cancer cells, reprogramming the metabolism to utilize the aerobic glycolysis pathway preferentially.

Conclusions: In conclusion, our study shows that PAF1/PD2 rewires the metabolism of PDAC by interacting with HIF1 α to regulate the expression of LDHA, which is the rate-limiting step of aerobic glycolysis.

Citation Format: Ayoola O. Ogunleye, Neelanjana Gayen, Saravanakumar Marimuthu, Rama Krishna Nimmakayala, Sanchita Rauth, Zahraa Alsafwani, Jesse L. Cox, Surinder K. Batra, Moorthy P. Ponnusamy. PAF1 reprograms metabolism in pancreatic cancer by interacting with HIF1α [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 1794.