Abstract
As ovarian cancer progresses, increased glucose use causes a glucose shortage in the tumor microenvironment. Therefore, it is crucial to find drugs that can effectively kill cancer cells in this energy stress setting. Here, we propose an effective therapeutic strategy that combines nutrient restriction with metformin to combat tumors. This study investigated the effects of metformin on ovarian cancer cells under energy stress conditions, mimicking the nutrient-deprived tumor microenvironment. We revealed that Metformin (10 mM) significantly reduced cell viability and proliferation under glucose deprivation conditions. Furthermore, it enhanced apoptosis and ferroptosis, as demonstrated by alterations in apoptotic protein expression and elevated levels of lipid reactive oxygen species (ROS), malondialdehyde (MDA), lipid peroxidation (LPO), and Fe2+. Transcriptional profiling revealed significant alterations in genes related to iron homeostasis and oxidative phosphorylation. Moreover, Metformin was found to induce mitochondrial dysfunction without affecting mitochondrial DNA or the expression of enzymes in the tricarboxylic acid (TCA) cycle, resulting in decreased ATP production and compromised activities of the respiratory chain complexes. The direct interaction between metformin and the NDUFB4 subunit in mitochondrial complex I was corroborated through the application of cellular thermal shift assay (CETSA) and drug affinity responsive target stability (DARTS) assays. In vivo, the combination of metformin and fasting cycles significantly inhibited SKOV3 cell-derived xenograft tumors in immunodeficient mice. Altogether, we have demonstrated that Metformin potentiates apoptosis and ferroptosis in ovarian cancer cells under energy stress conditions by targeting the NDUFB4 subunit of mitochondrial complex I, thus laying the groundwork for clinical testing. This study, though limited to cellular and animal levels, provides valuable insights into the therapeutic potential of metformin in ovarian cancer treatment.