circRNA hsa_circ_0001819抑制铁死亡并促进结直肠癌细胞恶性表型的作用及潜在机制OA

Background and Aims:Ferroptosis is an iron-dependent form of regulated cell death characterized by lipid peroxidation and has potential applications in colorectal cancer(CRC)therapy.Circular RNAs(circRNAs)can regulate tumor progression through competing endogenous RNA(ceRNA)mechanisms;however,their roles and regulatory mechanisms in CRC ferroptosis remain incompletely understood.This study aimed to identify dysregulated circRNAs in CRC,investigate the effects of hsa_circ_0001819(circ1819)on ferroptosis and malignant phenotypes of CRC cells,and preliminarily explore its potential molecular mechanism. Methods:CircRNA microarray datasets GSE223001 and GSE205643 were integrated to identify differentially expressed circRNAs,with GSE126094 used for validation.The expression of circ1819 in CRC tissues and cell lines was examined by qRT-PCR.RNase R digestion,actinomycin D treatment,and nuclear-cytoplasmic fractionation assays were performed to characterize its circular structure,stability,and subcellular localization.Following siRNA-mediated circ1819 knockdown,cell viability,lipid reactive oxygen species(ROS),malondialdehyde(MDA),and ferroptosis-related proteins were assessed in the presence of the ferroptosis inducer RSL3 and inhibitor Liproxstatin-1(Lip-1).CCK-8,colony formation,and Transwell assays were used to evaluate cell proliferation and migration.AGO2 RNA immunoprecipitation(AGO2-RIP),RNA pulldown,and bioinformatics analyses were performed to investigate the potential ceRNA regulatory mechanism of circ1819. Results:Circ1819 was significantly upregulated in CRC tissues and cell lines,and its expression was associated with tumor diameter and T stage.Circ1819 exhibited typical characteristics of a circular RNA and was predominantly localized in the cytoplasm.Circ1819 knockdown significantly increased the sensitivity of CRC cells to RSL3-induced ferroptosis,as evidenced by reduced cell viability and increased lipid ROS and MDA levels;these effects were partially reversed by Lip-1.Circ1819 knockdown significantly reduced GPX4 mRNA and protein expression,whereas SLC7A11 and ACSL4 expression remained unchanged.Moreover,circ1819 knockdown significantly inhibited CRC cell proliferation,colony formation,and migration.AGO2-RIP and RNA pulldown assays suggested interactions between circ1819 and miR-618 or miR-1231.Combined with target prediction and enrichment analyses,a potential circ1819-centered circRNA-miRNA-mRNA regulatory network was constructed. Conclusion:Circ1819 is aberrantly upregulated in CRC,and its knockdown enhances ferroptosis sensitivity while suppressing proliferation and migration of CRC cells.These effects may be associated with ceRNA regulation involving miR-618 and miR-1231 and alterations in GPX4 expression.Circ1819 may represent a potential regulatory link between malignant progression and ferroptosis resistance in CRC,although its downstream targets and causal regulatory relationships require further validation.