Molecular characteristics and tumorigenicity of ascites‐derived tumor cells: mitochondrial oxidative phosphorylation as a novel therapy target in ovarian cancer

Abstract

Ovarian cancer disseminates primarily intraperitoneally. Detached tumor cell aggregates (spheroids) from the primary tumor are regarded as ‘metastatic units’ that exhibit a low sensitivity to classical chemotherapy, probably due to their unique molecular characteristics. We have analyzed the cellular composition of ascites from OvCa patients, using flow cytometry, and studied their behavior in vitro and in vivo . We conclude that ascites‐derived cultured cells from OvCa patients give rise to two subpopulations: adherent cells and non‐adherent cells. Here, we found that the AD population includes mainly CD90 + cells with highly proliferative rates in vitro but no tumorigenic potential in vivo , whereas the NAD population contains principally tumor cell spheroids (EpCAM + /CD24 + ) with low proliferative potential in vitro . Enriched tumor cell spheroids from the ascites of high‐grade serous OvCA patients, obtained using cell strainers, were highly tumorigenic in vivo and their metastatic spread pattern precisely resembled the tumor dissemination pattern found in the corresponding patients. Comparative transcriptome analyses from ascites‐derived tumor cell spheroids ( n = 10) versus tumor samples from different metastatic sites ( n = 30) revealed upregulation of genes involved in chemoresistance ( TGM1 , HSPAs, MT1s), cell adhesion and cell‐barrier integrity ( PKP3 , CLDNs, PPL ), and the oxidative phosphorylation process. Mitochondrial markers (mass and membrane potential) showed a reduced mitochondrial function in tumoroids from tumor tissue compared with ascites‐derived tumor spheroids in flow cytometry analysis. Interestingly, response to OXPHOS inhibition by metformin and IACS010759 in tumor spheroids correlated with the extent of mitochondrial membrane potential measured by fluorescence‐activated cell sorting. Our data contribute to a better understanding of the biology of ovarian cancer spheroids and identify the OXPHOS pathway as new potential treatment option in advanced ovarian cancer.

Metabolic Reprogramming in Tumor-Associated Macrophages in the Ovarian Tumor Microenvironment

“…Inhibition of mitochondrial OXPHOS is known for preventing the reprogramming of pro-inflammatory M1 macrophages to the anti-inflammatory M2 phenotype, reducing tumor burden. This was further supported by a study where metformin and IACS010759-mediated inhibition of OXPHOS has reduced the tumor burden [ 80 ]. Interestingly, studies have shown that combinatorial treatment with metformin and the glycolytic inhibitor 2-deoxyglucose (2-DG) is effective in a broad spectrum of pre-clinical cancer models [ 81 ].…”

Development of adaptive anoikis resistance promotes metastasis that can be overcome by CDK8/19 Mediator kinase inhibition

“…Prior studies have implicated anoikis resistance as a phenotype of metastatic and chemo resistant cells. 43,5,44 45 Given that reversion to the original anoikis state occurred in the absence of stress ( Fig 2D ) we tested if such an acquired ‘tolerance’ rather than permanent resistance (intrinsic), was sufficient to alter in vitro tumorigenic properties. A transwell migration assay revealed that OV90-AnR cells (cells derived from P7) were able to undergo significantly higher migration through fibronectin ( Fig 3A ) as compared to the parental population (P0), and also as compared to cells expanded after exposure to a single round of suspension culture (P1, Fig 3A ) .…”

“…Ovarian cancer is the most devastating of gynecological cancers (fifth in cancer deaths among women) and an archetypal example of a cancer that leverages the metastatic hallmark of anoikis resistance for both trancoelomic/intraperitoneal and distant metastasis . [4][5][6][7][8] Accumulation of malignant ascites in the peritoneal cavity occurs as disease progresses, and this process necessitates suspension survival and/or bypass of cell death mechanisms in tumor cells. [9][10][11][12] The precise mechanisms by which cells acquire such anoikis resistance and adapt for apoptosis avoidance as a result of detachment stress remains a subject of intense investigation.…”

Metabolic reprogramming of the tumor immune microenvironment in ovarian cancer: A novel orientation for immunotherapy

“…The local low-glucose environment contributes to the expansion of chemical resistance to paclitaxel in ovarian cancer cells, creating a vicious cycle (30). Mitochondrial oxidative phosphorylation (OXPHOS) and the pentose phosphate pathway (PPP) were upregulated in ovarian cancer cells with metastatic capacity (31,32). Glutamate is used by ovarian cancer cells in mitochondrial OXPHOS to produce adenosine triphosphate (ATP) and other biomolecules necessary for aggressive expansion and migration (33).…”