Ovarian cancer is the deadliest gynecological
cancer in women, with a survival rate of less than 30% when the
cancer has spread throughout the peritoneal cavity. Aggregation of
cancer cells increases their viability and metastatic potential; however, there are limited studies that correlate these functional changes to specific phenotypic alterations. In this study, we investigated changes in mitochondrial morphology and dynamics during malignant transition using our
MOSE cell model for progressive serous
ovarian cancer. Mitochondrial morphology was changed with increasing
malignancy from a filamentous network to single, enlarged organelles due to an imbalance of mitochondrial dynamic
proteins (fusion: MFN1/OPA1, fission: DRP1/FIS1). These phenotypic alterations aided the adaptation to
hypoxia through the promotion of autophagy and were accompanied by changes in the mitochondrial ultrastructure, mitochondrial membrane potential, and the regulation of
reactive oxygen species (ROS) levels. The tumor-initiating cells increased mitochondrial fragmentation after aggregation and exposure to
hypoxia that correlated well with our previously observed reduced growth and respiration in spheroids, suggesting that these alterations promote viability in non-permissive conditions. Our identification of such mitochondrial phenotypic changes in
malignancy provides a model in which to identify targets for interventions aimed at suppressing
metastases.