DISTINCT SURVIVAL STRATEGIES OF PDAC CELLS UNDER STRESS: ECM-DEPENDENT ADAPTATION TO NUTRIENT DEPRIVATION AND QUIESCENCE UPON KRAS INHIBITION

Pancreatic cancer remains one of the most lethal forms of cancer, due in part to its ability to adapt to stressful conditions such as a nutrient-deprived microenvironment or chemotherapy. Here, we investigated the role of the extracellular matrix (ECM) in supporting the growth of PDAC cells in nutrient-deprived conditions. We found that the ECM supported PDAC cell proliferation under nutrient deprivation. Our metabolomics analysis revealed that PDAC cells upregulated the Arginine and proline metabolic pathway in the presence of Matrigel, coupled with a Matrigel-dependent increase in ASS1 expression, the rate-limiting enzyme in the de novo synthesis of Arginine. Furthermore, Matrigel-dependent mTORC1 activation was required for Matrigel-dependent proliferation of glucose-deprived PDAC cells. In contrast, Matrigel internalisation mediated Matrigel-dependent proliferation of glutamine-deprived PDAC cells. We also investigated the effects of MRTX1133, a KRAS G12D inhibitor, on PDAC cells and showed that MRTX1133 caused a significant reduction in cell number and EdU incorporation in PDAC cells with the KRAS G12D mutation, with no corresponding increase in cell death. Flow cytometry analysis confirmed that MRTX1133-treated cells were in the quiescent G0 phase of the cell cycle, and dye retention assay revealed that MRTX1133-treated cells retained the dye compared to cells treated with the vehicle control, where proliferation resulted in dye dilution. This suggests that MRTX1133-treated cells are not dividing or are dividing at a significantly slower rate than vehicle control. Importantly, upon MRTX1133 removal, cells resumed proliferation, indicating that quiescence induced by MRTX1133 was reversible. Finally, metabolomics analysis showed that β-oxidation of fatty acid-related metabolites were upregulated in MRTX1133-treated cells, suggesting their reliance on β-oxidation of fatty acid for survival. Overall, our study established that the ECM remodels PDAC cell metabolism to support their growth under nutrient-limiting conditions, while KRAS inhibition induces a quiescent state in PDAC, potentially resulting in treatment resistance and survival of PDAC cells.