Mfn1-mediated imbalanced mitochondrial dynamics promotes ovarian cancer stemness by inducing metabolic reprogramming.

Abstract

Ovarian cancer (OC) is the leading cause of death from reproductive system cancer among women worldwide. Ovarian cancer stem cells (OCSCs) are critically involved in metastasis, tumor recurrence, and chemoresistance, and are a significant bottleneck in the treatment. Several studies demonstrated metabolic rewiring and altered mitochondrial dynamics in CSCs. However, the role of Mfn1-mediated imbalanced mitochondrial dynamics in ovarian cancer stemness remains poorly understood. In this study, quantification of mtDNA indicates that CSCs have increased mitochondrial mass compared to the parental adherent cells. CD133+ enriched cells and cancer stem-like cells (spheroid cultured from OC cells) have higher Mfn1 expression and mitochondrial fusion activity. CSCs have increased oxidative phosphorylation (OXPHOS), ATP, and reduced ROS compared to the parental adherent cells. Disruption of mitochondrial dynamics by depletion of Mfn1 modulates the growth and size of spheroid formation and OC stemness. Seahorse analyzer analysis confirms the functional impact of Mfn1 knockdown on mitochondrial respiration. Overexpression of Mfn1 in SKOV-3 cells, which have a naturally low level of Mfn1, induces increased mitochondrial respiration. Furthermore, to elucidate the relationship between Mfn1 and OXPHOS complex activities and their role in OC stemness, we treated OC cells with 2-Deoxy-D-glucose (2DG), which induces OXPHOS and modulates the cancer stemness through Mfn1. During stemness acquisition, CSCs undergo Mfn1-mediated mitochondrial rearrangement, which could be a potential therapeutic strategy against ovarian cancer.