Upregulation of Succinate Dehydrogenase (SDHA) Contributes to Enhanced Bioenergetics of Ovarian Cancer Cells and Higher Sensitivity to Anti-Metabolic Agent Shikonin

SIMPLE SUMMARY: In recent years, targeting tumor specific metabolism has gained an interest as a promising therapeutic strategy. We discovered that the overexpression of mitochondrial enzyme succinate dehydrogenase (SDHA) is highly prevalent in ovarian carcinoma patients and contributes to elevated mitochondrial metabolism in ovarian tumor models. The SDHA overexpressing tumor cells are highly metabolically active, relying on both glycolysis and oxidative phosphorylation in mitochondria to meet their energy requirements. Further, we found that those cells are particularly vulnerable to deprivation of essential nutrients such as glucose and glutamine, which led to a substantial reduction of ATP yield. Lastly, we identified an anti-metabolic compound shikonin, which demonstrated a potent anti-tumor efficacy against SDHA overexpressing ovarian cancer cells. Overall, we strive to advance scientific knowledge by uncovering the previously unappreciated role of SDHA in reprogramming of ovarian cancer metabolism, which holds untapped opportunities for therapeutic intervention. ABSTRACT: We discovered that the overexpression of mitochondrial enzyme succinate dehydrogenase (SDHA) is particularly prevalent in ovarian carcinoma and promotes highly metabolically active phenotype. Succinate dehydrogenase deficiency has been previously studied in some rare disorders. However, the role of SDHA upregulation and its impact on ovarian cancer metabolism has never been investigated, emphasizing the need for further research. We investigated the functional consequences of SDHA overexpression in ovarian cancer. Using proteomics approaches and biological assays, we interrogated protein content of metabolic pathways, cell proliferation, anchorage-independent growth, mitochondrial respiration, glycolytic function, and ATP production rates in those cells. Lastly, we performed a drug screening to identify agents specifically targeting the SDHA overexpressing tumor cells. We showed that SDHA overexpressing cells are characterized by enhanced energy metabolism, relying on both glycolysis and oxidative phosphorylation to meet their energy needs. In addition, SDHA-high phenotype was associated with cell vulnerability to glucose and glutamine deprivation, which led to a substantial reduction of ATP yield. We also identified an anti-metabolic compound shikonin with a potent efficacy against SDHA overexpressing ovarian cancer cells. Our data underline the unappreciated role of SDHA in reprogramming of ovarian cancer metabolism, which represents a new opportunity for therapeutic intervention.