Glutamine modulates stress granule formation in cancer cells through core RNA-binding proteins.

Cytoplasmic stress granules (SGs) induced by various stresses have been linked to cancer and other disorders. Which active energy pathways are required for SG formation remains unclear. We used nutrient deprivation to show that glutamine is the sole amino acid source governing whether cancer cells form SGs. Metabolic profiling revealed the essential functions of glutamine and glucose in SG formation under limiting metabolic conditions. Providing glutamine during metabolic stress restored ATP levels in cancer cells and revived many essential gene expression patterns. MYC, a known regulator of the shift between glucose and glutamine metabolism, showed increased expression as cells moved to glutamine uptake. Inhibition of MYC prevented SG formation even with glutamine present and increased cell death after arsenite exposure. The RNA-binding proteins G3BP1 and G3BP2 (collectively G3BP1/2) were required for glutamine utilization, with G3BP1/2-knockout cells displaying a heavier reliance on glucose, yielding reduced cell survival and an inability to properly utilize glutamine. Altogether, we show that cancer cells require glutamine for SG formation under nutrient deprivation, and its absence reduces cell survival, lowering ATP levels below an energy threshold required for SG formation.