BNIP3L/BNIP3-Mediated Mitophagy Contributes to the Maintenance of Ovarian Cancer Stem Cells

Ovarian cancer remains the most lethal gynaecological malignancy, with tumour recurrence and chemoresistance posing significant therapeutic challenges. Emerging evidence suggests that cancer stem cells (CSCs), a rare subpopulation within tumours with self-renewal and differentiation capacities, contribute to these hurdles. Therefore, elucidating the mechanisms that sustain CSCs is critical for improving treatment strategies. Mitophagy, a selective process for eliminating damaged mitochondria, plays a key role in maintaining cellular homeostasis, including CSC survival. Our study demonstrates that ovarian CSCs exhibit enhanced mitophagy, accompanied by elevated expression of the mitochondrial outer membrane receptors BNIP3 and BNIP3L. Knockdown of BNIP3 or BNIP3L significantly reduces mitophagy and impairs CSC self-renewal, indicating that receptor-mediated mitophagy is essential for CSC maintenance. Mechanistically, we identify that hyperactivated NF-κB signalling drives the upregulation of BNIP3 and BNIP3L in ovarian CSCs. Inhibition of NF-κB signalling, either via p65 knockdown or pharmacological inhibitors, effectively suppresses mitophagy. Furthermore, we demonstrate that elevated DNA-PK expression contributes to the constitutive activation of NF-κB signalling, thereby promoting mitophagy in ovarian CSCs. In summary, our findings establish that BNIP3/BNIP3L-mediated mitophagy, driven by DNA-PK-dependent NF-κB hyperactivation, is essential for CSC maintenance. Targeting the DNA-PK/NF-κB/BNIP3L-BNIP3 axis to disrupt mitochondrial quality control in CSCs represents a promising therapeutic strategy to prevent ovarian cancer recurrence and metastasis.