INSIG1/2 succination mediated by the moonlighting function of ADSL promotes lipogenesis and liver tumorigenesis

Aerobic glycolysis supports tumor growth, but how tumor cells sense glucose to coordinate biosynthesis remains largely unclear. Here we show that in hepatocellular carcinoma cells, glucose-activated PKCε phosphorylates the purine synthesis enzyme ADSL, triggering its translocation to the endoplasmic reticulum. ADSL then promotes succination of INSIG1/2, which disrupts the interaction between INSIG proteins and SCAP, leading to the translocation of the SCAP-SREBP complex to the Golgi, the activation of SREBP-1 and the transcription of downstream lipogenesis-related genes, proliferation of tumor cells, and tumorigenesis in mice. Through virtual screening, we identify Elsulfavirine, an approved HIV drug, which blocks ADSL-INSIG interaction and suppresses SREBP-1 activation induced by glucose. Combining Elsulfavirine with Lenvatinib synergistically inhibits tumor growth. Clinically, ADSL phosphorylation and INSIG succination correlate with SREBP-1 activation and poor prognosis in human HCC. In summary, these findings reveal a repurposing mechanism by which tumor cells coordinate glucose metabolism and lipogenesis via a moonlighting function of ADSL and underscore a repurposing strategy for liver cancer therapy.