Human ovarian cancer stem cells (HuOCSCs) are the main source of ovarian cancer recurrence, metastasis, and drug resistance. Superparamagnetic iron oxide nanoparticles (SPIONs) are well-known nucleic acid or drug carriers owing to their controllable properties, superior stability, and
easy modification. However, whether SPIONs can inhibit the activity of HuOCSCs by inducing ferroptosis remains unclear. In the present study, we isolated CD44+ /CD133+ HuOCSCs from tumours of four patients with clear cell ovarian cancer and added 0.2 mM SPIONs for mixed
culture. Transmission electron microscopy showed that SPION-treated HuOCSCs contained multiple high-density electron clouds. Prussian blue staining showed high concentrations of iron ions in the cells. In vitro , SPIONs treatment of HuOCSCs inhibited cell proliferation, migration, and soft
agar clone formation, weakened their resistance to multiple chemotherapeutics, and induced cell death. In vivo , SPIONs pretreatment of HuOCSCs significantly reduced their tumour-forming ability and induced angiogenesis in nude mice. Further, SPIONs induced the accumulation of reactive oxygen
species in HuOCSCs and induced oxidative stress. qPCR analysis indicated that SPIONs-treated HuOCSCs had reduced expression of tumour stem cell markers (CD117, NANOG, CD133, and SOX2), cell proliferation factors (KI67, CCND), autophagy-related factors (ATG3, ATG5, MAP1ALC3a, MAP1ALC3b, and
MAP1ALC3c), and certain negative regulators of ferroptosis, while the mRNA expression levels of cell death-related proteins (BAK1 and BID), and certain positive regulators of ferroptosis were significantly increased. Overall, our findings suggest that SPIONs induce oxidative stress and decrease
autophagy activity in ovarian cancer stem cells, activate ferroptosis, and inhibit their proliferation, invasion, drug resistance, and tumorigenic ability.
The potential therapeutic effect of melatonin on human ovarian cancer by inhibition of invasion and migration of cancer stem cells
