Autor:innen:
L. Huhnold (Göttingen, DE)
I. Bogeski (Göttingen, DE)
P. Rehling (Göttingen, DE)
K. Reutlinger (Göttingen, DE)
S. Mercan (Göttingen, DE)
A. Boshnakovska (Göttingen, DE)
C. Gibhardt (Göttingen, DE)
J. Hamm (Göttingen, DE)
G. Poschet (Heidelberg, DE)
M. Büttner (Heidelberg, DE)
Z. Bonilla del Rio (Göttingen, DE)
U. Latif (Göttingen, DE)
V. Ellenrieder (Göttingen, DE)
Background: Pancreatic ductal adenocarcinoma (PDAC) is characterized by a highly aggressive phenotype and severe resistance to chemotherapy, culminating these features in the NFATc1high subtype that accounts for 10-15% of all PDAC patients. These characteristics are promoted by metabolic rewiring of cancer cells in nutrient-poor microenvironment. Distinctive, altered glutamine (Gln) metabolism becomes crucial for bioenergetics, nucleotide synthesis, biosynthesis and antioxidants. However, the underlying mechanisms and its clinical implications remain elusive. Our aim is to expose potential vulnerabilities to chemotherapy by defining the role of the Nuclear Factor of Activated T-Cells 1 (NFATc1) in survival mechanisms and metabolic hallmarks in pancreatic cancer.
Methods: We employed in vitro experiments using PDAC cell lines, patient-derived-xenografts and organoids to determine gene regulation, cellular stress responses and metabolism in concert to NFATc1, Calcium signalling, chemotherapeutics, nutrient-depleted conditions and signalling inhibition of key enzymes. Quantitative, functional and molecular characterization was performed through e.g. RNA- and Chromatin-Immunoprecipitation-DNA Sequencing, Mass-Spectrometry, Seahorse-Analysis, qPCR, Western-Blot, Immunofluorescence microscopy, Viability-Assays, Live-Cell-Imaging, Single-Cell-Measurements and Reporter-Assay.
Results: We show that NFATc1 highly correlates to the expression and activity of key enzymes in Gln catabolism and calcium signalling, e.g. glutaminase (GLS) and MCU, leading to a shift in energy homeostasis by enhanced production of the energy exchange factor ATP and increased glutathione requirements. Functionally, loss of NFATc1 was accompanied by a reduced production of ATP and increase of cytotoxic reactive oxygen species. Nutrient scarcity, GLS inhibition (CB-839) and NFATc1 Inhibition (9-Ing-41, mediated through GSK3ß) in tumour cells with high NFATc1 activity levels result in massive decrease of growth and viability – most effective in combined treatment strategies, whereas low levels of NFATc1 show less vulnerability. Moreover, the expression of NFATc1 is compromised by Gln deprivation. Finally, cisplatin treatment combined with signalling inhibition of NFATc1 or its mediated metabolic pathways significantly decreases oxidative phosphorylation and cell viability in contrast to chemotherapeutic treatment alone.
Conclusion: We demonstrate that NFATc1 is linked to progression and resistance of PDAC through metabolic reprogramming by ensuring mitochondrial fitness. Importantly, the metabolic shift leads to Gln addiction, resulting in high vulnerability to inhibition of NFATc1 and its signalling pathways. Overall, the cooperation between Gln metabolism and NFATc1 provides potential therapeutic targets for the aggressive NFATc1high subtype by disrupting its metabolic balance, orchestrating a theoretical platform for novel tailored treatment strategies.