Targeting both the enzymatic and non-enzymatic functions of DHODH as a therapeutic vulnerability in c-Myc-driven cancer.

Abstract

c-Myc (Myc)-driven cancers exhibit aggressive phenotypes and therapeutic resistance. Here, integrating CRISPR-Cas9 screening, we identify dihydroorotate dehydrogenase (DHODH) as a promising target in Myc-driven cancer. Mechanistically, DHODH interacts with Myc to stabilize it independently of its enzymatic activity, thereby antagonizing SKP2-mediated polyubiquitination and proteasomal degradation. EN4, a Myc transcriptional activity inhibitor, disrupts DHODH-Myc interaction, promoting Myc degradation via SKP2. Additionally, Myc transcriptionally activates DHODH, enhancing pyrimidine biosynthesis and ferroptosis defense, processes dependent on DHODH enzymatic activity. Clinically, DHODH positively correlates with Myc, activating pyrimidine metabolism and ferroptosis defense in Myc-driven cancers. Hyperactivation of the DHODH-Myc axis is linked to colorectal cancer progression and poor prognosis. Therapeutically, combining EN4 with a DHODH enzymatic inhibitor demonstrates potent antitumor efficacy in Myc-driven colorectal cancer. Overall, our findings elucidate the metabolic and non-metabolic roles of DHODH in Myc-driven cancer, underscoring its dual potential as a therapeutic target addressing both enzymatic and non-enzymatic functions.