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.

(1) Background. PDX models have become the preferred tool in research laboratories seeking to improve development and pre-clinical testing of new drugs. PDXs have been shown to capture the cellular and molecular characteristics of human tumors better than simpler cell line-based models. More recently, however, hints that PDXs may change their characteristics over time have begun to emerge, emphasizing the need for comprehensive analysis of PDX evolution. (2) Methods. We established a panel of high-grade serous ovarian carcinoma (HGSOC) PDXs and developed and validated a 300-SNP signature that can be successfully utilized to assess genetic drift across PDX passages and detect PDX contamination with lymphoproliferative tissues. In addition, we performed a detailed histological characterization and functional assessment of multiple PDX passages. (3) Results. Our data show that the PDXs remain largely stable throughout propagation, with marginal genetic drift at the time of PDX initiation and adaptation to mouse host. Importantly, our PDX lines retained the major histological characteristics of the original patients’ tumors even after multiple passages in mice, demonstrating a strong concordance with the clinical responses of their corresponding patients. (4) Conclusions. Our data underline the value of defined HGSOC PDXs as a pre-clinical tumor model.

Background: Ovarian cancer is the deadliest of all gynecologic malignancies due to limited therapeutic options. Our data show that the tumor-specific metabolism of ovarian cancer could be effectively targetable, which highlights a path for new anti-cancer therapies. Methods and Results: Our work shows that the upregulation of mitochondrial enzyme SDHA is particularly prevalent in ovarian carcinoma. SDHA overexpression significantly induced orthotopic ovarian tumor growth, reducing mouse survival. We showed that SDHA-overexpressing tumors depend on glutaminolysis and increased activity of the tricarboxylic acid (TCA) cycle coupled with mitochondrial oxidative phosphorylation (OXPHOS), which are essential for high-energy metabolism and cell survival. We identified a distinctive vulnerability of SDHA-overexpressing tumors to agents targeting regulators of the OXPHOS pathway, particularly the LRPPRC protein. LRPPRC is a key regulator of mitochondrial energy metabolism, promoting OXPHOS and ATP generation. However, when overexpressed, the LRPPRC acts as a tumor oncogene. Our analysis of SDHA and LRPPRC gene and protein expression patterns in precursor lesions and established ovarian cancer demonstrated that the upregulation of SDHA is accompanied by LRPPRC overexpression, notably in advanced tumors. Our novel findings highlight for the first time a potential functional interaction between SDHA and LRPPRC in the development and progression of ovarian malignancy. Importantly, our in vivo data showed that pharmacological inhibition of LRPPRC results in a lasting therapeutic benefit and can be an effective therapy in SDHA- and LRPPRC-overexpressing ovarian tumors. Conclusions: Overall, our study underlines an understudied role of concomitant overexpression of SDHA and LRPPRC in ovarian cancer pathogenesis, highlighting new paths for therapeutic development.

Ovarian cancer is the deadliest of all gynecologic malignancies due to limited therapeutic options. Our data show that tumor-specific metabolism of ovarian cancer could be effectively targetable, which highlights a path for new anti-cancer therapies. Our work showed that the upregulation of mitochondrial enzyme SDHA is particularly prevalent in ovarian carcinoma. The SDHA overexpression significantly induced orthotopic ovarian tumor growth substantially reducing mouse survival. We showed that the SDHA overexpressing tumors depend on glutaminolysis, and increased activity of TCA cycle coupled with mitochondrial oxidative phosphorylation (OXPHOS), which are essential for high-energy metabolism and cell survival. We also identified a distinctive vulnerability of SDHA overexpressing tumors to agents targeting regulators of OXPHOS pathway, particularly LRPPRC protein. LRPPRC is a key regulator of mitochondria homeostasis and energy metabolism promoting OXPHOS and ATP generation, however when overexpressed, the LRPPRC acts as tumor oncogene. Our analysis of SDHA and LRPPRC gene and protein expression patterns in precursor lesions and established ovarian cancer demonstrated that the upregulation of SDHA is accompanied by LRPPRC overexpression, particularly in advanced tumors. Our novel findings highlight for the first time a potential functional interaction between SDHA and LRPPRC in development and progression of ovarian malignancy. Importantly, our in vivo data showed that pharmacological blocking LRPPRC function results in a long-term therapeutic benefit and can be an effective therapy in SDHA and LRPPRC overexpressing ovarian tumors. Overall, our study underlines an understudied role of concomitant overexpression of SDHA and LRPPRC in ovarian cancer pathogenesis highlighting new opportunities for therapeutic intervention.