Glutamine-dependent changes in fibroblast-derived extracellular matrix dictate cancer cell behavior.

The extracellular matrix (ECM) provides key biochemical and biomechanical cues that govern fundamental cellular processes, including growth and migration. ECM dysregulation and altered cell-matrix interactions are drivers of cancer progression, exemplified by pancreatic ductal adenocarcinoma (PDAC), where an abnormally dense, collagen-rich, and stiff ECM correlates with poor patient outcomes. The PDAC microenvironment is poorly perfused, resulting in altered nutrient availability, yet how this metabolic stress shapes the ECM and its biological activity remains largely unknown. Herein, using murine and patient-derived fibroblasts, we demonstrate that glutamine, a key amino acid depleted in poorly perfused PDAC regions, regulates the biochemical composition, mechanical properties, and biological activity of fibroblast-derived ECM. As glutamine availability decreases, fibroblasts shift from producing an interstitial, mature ECM enriched in fibrillar collagens toward a basement membrane-like ECM. Consistent with these observations, glutamine stress inversely correlates with fibrillar collagen expression in CAFs in patients with PDAC. ECM produced under low glutamine conditions is depleted in collagen I, more elastic, and promotes PDAC cell growth compared to ECM generated under glutamine-rich conditions. Reducing the stiffness of such matrices is sufficient to increase PDAC cell growth. Glutamine-dependent changes in ECM composition, stiffness, and biological activity are driven in part by glutamine-regulated alpha-ketoglutarate availability in fibroblasts. These findings establish nutrient availability as a key regulator of ECM biology and suggest the nutrient-dictated ECM as a novel mechanism by which glutamine stress in the tumor microenvironment shapes cancer cell behavior.