ISGylation promotes ALDOA stability and PKM2-dependent activation to fuel colorectal cancer metabolism

Abstract ISG15 overexpression in cancers has emerged as a diagnostic marker and therapeutic target. This study identifies ISGylation, a post-translational modification mediated by ISG15, as a critical driver of CRC progression through metabolic reprogramming and oncogenic signaling. Clinical and multi-omics analyses reveal elevated ISG15 and ISGylation levels in CRC tissues, correlating with advanced clinicopathological features and poor prognosis. Functional experiments demonstrate that ISG15 knockdown inhibits CRC cell proliferation and tumor growth in vitro and in vivo. Mechanistically, ISGylation enhances glycolytic activity via ALDOA, which is modified at lysine residues K42 and K147 to resist ubiquitination and boost enzymatic function. ISGylation further promotes PKM2-mediated ALDOA phosphorylation at S36, enhancing the enzymatic activity of ALDOA to amplify glycolysis. HERC5 acts as the specific E3 ligase for ALDOA ISGylation, while USP18 reverses this process. Modulation of this axis with TEPP-46 mimics the antitumor effects produced by the inhibition of ISGylation, underscoring its biological significance. These findings suggest ISGylation/ALDOA as an important metabolic regulatory pathway in CRC, highlighting the ISGylation-ALDOA axis as a promising intervention target.