DIO3 depletion attenuates ovarian cancer growth via reduced glycolysis and alterations in glutamine metabolism.

OBJECTIVE: Metabolic reprogramming emerges as a central driver of therapy resistance and survival disadvantage in ovarian cancer. We recently demonstrated that inhibiting the enzyme Deiodinase type 3 (DIO3) reduces ovarian cancer growth, although the underlying mechanism remains unclear. METHODS: We studied DIO3 role in metabolism in genetically manipulated ovarian cancer cells using protein expression analysis, integrative proteomics, endogenous and extracellular metabolomics, metabolic assays including lactate and glutamate secretion, reactive oxygen species (ROS) production and the Seahorse Cell Mito Stress test. RESULTS: We reveled that inhibiting DIO3 suppresses glycolysis while enhancing ATP production through oxidative phosphorylation (OXPHOS). We corroborated these findings using two models of ovarian cancer xenografts, demonstrating a marked reduction in glycolytic proteins upon silencing or inhibiting DIO3 using our first in class small molecule. Moreover, altered glutamine metabolism was also documented, favoring urea cycle and TCA cycle engagement over antioxidant production, accompanied by elevated ROS. Intriguingly, DIO3 depletion in fallopian tube cells, the precursor of HGSOC, displayed distinct metabolic adaptations, including enhanced glycolysis and lipid metabolism, suggesting tissue-specific roles for DIO3. CONCLUSIONS: These collective findings position DIO3 as a potential regulator of ovarian cancer metabolism, with implications for targeting this enzyme to disrupt tumor energetics as a novel therapeutic approach.