Table 3.

List of circRNAs, their functional roles, and mechanisms of action in HCC.

Functional Role	CircRNAs	Mechanism	Refs.
MiR sponge or decoy	CircTRIM33-12	increases the production of TET1 by the sponging of miR-191, lowering the levels of 5-hydroxymethylcytosine in HCC cells	[100]
	CircMTO1	downregulates p21 level by sponging oncogenic miR-9 to inhibit HCC progression.	[101]
	CircHIPK3	regulates AQP3 expression, sponges miR-124, alters cell proliferation and HCC migration	[97]
	CircZFR	regulates cell proliferation, epithelial–mesenchymal transition, Wnt/β-catenin via quenching miR-3619-5p, enhancing CTNNB1 expression and activating Wnt/β-catenin signaling	[104]
	CircFBLIM1	ceRNA that enhances HCC progression via sponging miR-346	[105]
	CircMAT2B	encourages HCC malignancy, glycolysis, and miR-338-3p quenching to activate the PKM2 axis under hypoxic conditions	[43]
	CircTP63	sponges miR-155-5p and thus increases ZBTB18 expression, which is positively correlated with mortality rates in HCC patients	[106]
	CircSMARCA5	TIMP3 expression via sponging miR-17-3p and miR-181b-5p	[46]
	Circ_0001806	expedites HCC advancement by upregulating MMP-16 expression through the inhibition of miR-193a-5p	[107]
	CircYTHDF3	fosters HCC via miR-136-5p/CBX4/VEGF pathway	[108]
	CircCFH	promotes HCC by influencing cellular proliferation, apoptosis, migration, invasion and glycolysis via miRNA 377-3p/RNF38 axis	[109]
	CDR1as	interacts with markers and miR-1287 bands within the Raf1 pathways to modulate HCC progression	[110]
	CircASAP1	ceRNA for miR-326 and miR-532-5p regulates the expression of MAPK1 and CSF-1 targets, facilitating invasion, HCC cell proliferation and infiltration of tumor-associated macrophages	[42]
	CircSORE	induces sorafenib resistance by competitively activating the Wnt/β-catenin pathway through miR-103a-2-5p and miR-660-3p	[45]
Protein sponge or decoy	CircBACH1	interacts with HuR; RBP downregulates p27 expression, blocks translation in the p27 5′-untranslated region by an interferon-responsive sequence element, encourages HuR translocation and cytoplasmic accumulation	[111]
	CircZKSCAN1	competitively binding FMRP to modulate the translation of CCAR1 mRNA and inhibiting the Wnt signaling pathway	[112]
Protein scaffold	CircAMOTL1	combines with c-myc, STAT3, PDK1, and AKT1 to promote their translocation to the nucleus, modulating the expression of their target genes.	[113,114,115]
	CircRHOT1	recruits TIP60 to NR2F6, initiating NR2F6 transcription and HCC progression	[116]
	CircADD3	protein scaffold inhibits HCC metastasis via CDK1-mediated EZH2 ubiquitination	[117]
	CircPABPC1	a tumor suppressor, directly delivering ITGβ1 to the proteasome for HCC ubiquitin-independent destruction	[118]
	CircSORE	causes sorafenib resistance by binding oncogenic YBX1 and blocking its nuclear interaction with E3 ubiquitin ligase PRP19	[44]
Gene transcription regulation	CircIPO11	binds TOP1 to trigger GLI1 transcription, with Hedgehog signaling activation.	[119]
Translation to proteins and peptides	CircCTNNB1	creates 370 amino acid β-catenin isoform, uses circularization to block translation at a new stop codon, uses Wnt to stimulate HCC cell development	[120]
Epigenetic alterations’ regulation	CircSOD2	induces epigenetic alteration to drive HCC progression by activating JAK2/STAT3 signaling.	[121]

[AKT1: AKT serine/threonine kinase 1; AQP3: Aquaporin 3; CBX4: chromobox 4; CCAR1: cell division cycle and apoptosis regulator protein 1; CDK1: cyclin-dependent kinase 1; CTNNB1: catenin beta 1; CSF: colony-stimulating factor 1; EZH2: enhancer of zeste homolog 2; FMRP: fragile X mental retardation protein; GLI1: GLI family zinc finger 1; HCC: hepatocellular carcinoma; ITGβ1: integrin β1; MAPK: mitogen-activated protein kinase; miR: microRNA; Hur: human antigen R; JAK2: Janus kinase 2; MMP: matrix metalloproteinase; NR2F6: nuclear receptor subfamily 2 group F member 6; PDK1: 3-phosphoinositide-dependent kinase 1; PKM2: pyruvate kinase M2; RBP: RNA-binding protein; STAT3: signal transducer and activator of transcription 3; TIMP3: metalloproteinase 3; VEGF: vascular endothelial growth factor; YBX1: Y-box binding protein 1.]