Glutamine binds HSC70 to transduce signals inhibiting IFN-β-mediated immunogenic cell death

Abstract

Glutamine plays a role in cell signaling that regulates gene expression and impacts tumorigenesis. However, it is still unclear how glutamine transduces signals in cells. Here, we show that glutamine binds to heat shock cognate protein 70 (HSC70) to stimulate the deubiquitinase otubain domain containing protein (OTUD4) independently of known glutamine metabolic or signaling pathways, resulting in lactate dehydrogenase A (LDHA) stabilization via the microautophagy-lysosome pathway, increased lactate production and decreased expression of interferon (IFN)-β and its targets, hallmarks of immunogenic cell death (ICD). In cancer cell lines and patient-derived organoids and xenografts, glutamine depletion or glutamine transport inhibition combined with ICD-inducing chemotherapeutic drugs synergistically activates IFN-β, promotes CD8⁺ T cell recruitment, and inhibits cancer cell growth via the OTUD4/LDHA axis. CD8 expression is negatively correlated with expression of the glutamine transporter alanine/serine/cysteine transporter 2 (ASCT2), OTUD4, and LDHA in cancer patients. Thus, we identify an intracellular glutamine signaling pathway, and targeting this pathway is a promising strategy for cancer treatment.