Tau Aggregation‐Dependent Lipid Peroxide Accumulation Driven by the hsa_circ_0001546/14‐3‐3/CAMK2D/Tau Complex Inhibits Epithelial Ovarian Cancer Peritoneal Metastasis

Abstract Intraperitoneal dissemination is the main method of epithelial ovarian cancer (EOC) metastasis, which is related to poor prognosis and a high recurrence rate. Circular RNAs (circRNAs) are a novel class of endogenous RNAs with covalently closed loop structures that are implicated in the regulation of tumor development. In this study, hsa_circ_0001546 is downregulated in EOC primary and metastatic tissues vs. control tissues and this phenotype has a favorable effect on EOC OS and DFS. hsa_circ_0001546 can directly bind with 14‐3‐3 proteins to act as a chaperone molecule and has a limited positive effect on 14‐3‐3 protein stability. This complex recruits CAMK2D to induce the Ser324 phosphorylation of Tau proteins, changing the phosphorylation status of Tau bound to 14‐3‐3 and ultimately forming the hsa_circ_0001546/14‐3‐3/CAMK2D/Tau complex. The existence of this complex stimulates the production of Tau aggregation, which then induces the accumulation of lipid peroxides (LPOs) and causes LPO‐dependent ferroptosis. In vivo, treatment with ferrostatin‐1 and TRx0237 rescued the inhibitory effect of hsa_circ_0001546 on EOC cell spreading. Therefore, based on this results, ferroptosis caused by Tau aggregation occurs in EOC cells, which is not only in Alzheimer's disease‐ or Parkinson's disease‐related cells and this kind of ferroptosis driven by the hsa_circ_0001546/14‐3‐3/CAMK2D/Tau complex is LPO‐dependent rather than GPX4‐dependent is hypothesized.