IFRD1 promotes tumor cells “low-cost” survival under glutamine starvation via inhibiting histone H1.0 nucleophagy

Glutamine addiction represents a metabolic vulnerability of cancer cells although effective therapeutic targeting of the pathways involved remains to be realized. Here, we disclose the critical role of IFRD1 (interferon-related developmental regulator 1) in the adaptive survival of hepatocellular carcinoma cells (HCC) during glutamine starvation. The induction and translocation of IFRD1 to the endoplasmic reticulum inhibits autophagy by promoting proteasomal degradation of the key autophagy regulator ATG14 in a TRIM21-dependent manner. On the contrary, enforced IFRD1 loss increases autophagy flux leading to cell death. This effect is largely realized through the autophagy-dependent degradation of histone H1.0 causing globally enhanced chromatin accessibility associated with unchecked increases in ribosome and protein biosynthesis . This in turn leads to metabolic exhaustion and death under glutamine starvation. Practically, IFRD1 depletion in preclinical HCC models potentiates glutamine limiting strategies including synergizing with the glutaminase-1 selective inhibitor CB-839. Thus, IFRD1 supports the adaptive survival of cancer cells under glutamine starvation, with potential as a therapeutic target in anti-cancer applications.