Four fungal sterols inhibit SKOV3 via autophagy-ferroptosis and analysis of structure-activity relationships.

Ovarian cancer is one of the most lethal gynecological malignancies with poor prognosis due to high drug resistance and low tumor susceptibility. This study investigated the cytotoxic effects of four sterols of fungal origin, ergosterol (ES), cholesterol (CS), β-sitosterol (βS), and lanosterol (LS) on human ovarian cancer SKOV3 cells, revealing that they exert their effects by correlating with autophagy and ferroptosis‑related signaling, and analyzed the structure-activity relationship. SKOV3 tumor cells were treated with four types of sterols for 24 h. Cell viability, cell cycle, apoptosis, mitochondrial membrane potential, and the expression of proteins associated with autophagy and ferroptosis were assessed, and the correlation between their structure and antitumor activity was analyzed. All four sterols inhibited SKOV3 cell proliferation in a dose-dependent manner, with the IC50 values ranked as LS (28.32 μg/mL) < CS (32.07 μg/mL) < βS (73.53 μg/mL) < ES (78.67 μg/mL). The four sterols significantly suppressed cell migration, induced G0/G1 phase arrest and apoptosis, reduced mitochondrial membrane potential, and caused mitochondrial structural damage. Meanwhile, they markedly up-regulated the expression of LC3II/LC3I and P53, and down-regulated the expression of SLC7A11 and GPX4. The number of conjugated double bonds in sterols was negatively correlated with IC50, cell viability and migration rate, and positively correlated with apoptosis rate and key protein expression, the substituents at C24, C28 and C29 of the side chain also enhanced the cytotoxicity. These findings indicate that fungal sterols are associated with correlated regulation of the autophagy-ferroptosis network and P53 activation in SKOV3 cells, providing a theoretical basis for anti-ovarian cancer drug development.