Table 1.

Summary of circRNAs as a tumor suppressor in various tumors

Cancer type	CircRNA	Function	Mechanism	Reference
Hepatocellular carcinoma	CSMARCA5	MiRNA sponge	As sponges of miR‐17‐3p and miR‐181b‐5p to regulate miR‐17‐3p/miR‐181b‐5p‐TIMP3 axes	34
	CircZKSCAN1	Regulating the transcription of linear RNA	Acting as a competitive inhibitor to retain endogenous RNA	25
	CircADAMTS14	MiRNA sponge	Acting as a sponge of miR‐572 to regulate expression of RCAN1	37
	Hsa_circ_0079299	Interaction with protein	Inhibiting cell proliferation through PI3K/AKT/mTOR signaling pathway	40
	CircMTO1	MiRNA sponge	Binding with miR‐9 and regulating P21 expression	39
	CircARSP91	Interaction with protein	Suppressed by androgen receptor	41
	CircC3P1	MiRNA sponge	Acting as a sponge of miR‐4641 to promote PCK1 expression	42
	CircADAMTS13	MiRNA sponge	Acting as a sponge of miR‐484	38
Bladder cancer	CircFNDC3B	MiRNA sponge	Inhibiting G3BP2 expression and SRC/FAK phosphorylation by binding with miR‐1178‐3p	43
	CircITCH	MiRNA sponge	Acting as sponges of miR‐17 and miR‐224 to upregulate the expression of P21 and PTEN	44
	CircLPAR1	MiRNA sponge	Acting as a sponge of miR‐762	48
	CircHIPK3	MiRNA sponge	Acting as a sponge of miR‐558 and inhibiting heparanase expression, thereby inhibiting invasion and metastasis	45
	CircRNA‐3 (BCRC‐3)	MiRNA sponge	Interacting with miR‐182‐5p and subsequently promoting P27 activity	46
	Cdr1as	MiRNA sponge	Binding to miR‐135a	47
Gastric cancer	CircFAT1 (e2)	MiRNA sponge and interacting with RBP	Acting as a sponge of miR‐548g to regulate the expression of RUNX1; interacting with YBX1	32
	CircYAP1	MiRNA sponge	Acting as a sponge of miR‐367‐5p to upregulate the expression of P27	49
	CircLARP4	MiRNA sponge	Acting as a sponge of miR‐424 to regulate the expression of LATS1	28
	Hsa_circ_0000993	MiRNA sponge	Inhibit metastasis by chelation of miR‐214‐5p	51
	Hsa_circ_0000096	Interaction with protein	Regulating the expression of cyclin D1, CDK6, MMP‐2, and MMP‐9	50
	CircPSMC3	MiRNA sponge	Acting as a sponge of miR‐296‐5p to regulate the expression of PTEN	52
Breast cancer	CircASS1	MiRNA sponge	Inhibiting the expression of miR‐4443 by sponge activity, and upregulating the expression of ASS1	35
	Hsa_ circ_0072309	MiRNA sponge	Acting as a sponge of miR‐492	54
	Circ000911	MiRNA sponge	Promoting Notch1 expression by acting as a sponge of miR‐449a	53
Lung cancer	CircNOL10	Interaction with protein	Promoting the expression of human protein	55
	Circ0006916	MiRNA sponge	Combining to miR‐522‐3p to upregulate the expression of PHLPP1, thereby inhibiting cell cycle progression and inhibiting cancer progression	59
	Hsa_circ_100395	MiRNA sponge	Regulating miR‐1228/TCF21 axis	58
Non‐small cell lung cancer	CircPTK2	MiRNA sponge	Acting as sponges of miR‐429/miR‐200b‐3p, targeting TIF1γ to inhibit TGFβ‐induced EMT	56
	Circ_0001649	MiRNA sponge	Directly ejecting miR‐331‐3p and miR‐338‐5p	57
Glioblastoma multiforme	Circ_0001946	MiRNA sponge	Inhibiting miR‐6715p to promote the expression of CDR1	60
	CircFBXW7	Translation	Encoding FBXW7‐185aa and then reducing the half‐life of c‐Myc	61
	CircSHPRH	Translation	Encoding a 146‐aa protein, which protects its associated full‐length SHPRH	31
Colorectal cancer	CircIGA7	MiRNA sponge	Competitively binding miR‐370‐3p to upregulate NF1 translation and then inhibit Ras signaling pathway; upregulating the transcription of its host gene ITGA7 by inhibiting RREB1 by Ras	62
	Hsa_circ_0014717	Unknown	Acting as a potential tumor suppressor	63
Oral squamous cell carcinoma	Hsa_circ_0008309	MiRNA sponge	Regulating miR‐382‐5P/ATXN1 axis	64
Tube cancer	Circ0043898	Unknown	May serve as a target of histone H3 and BMI18	65

circRNA, circular RNA; EMT, epithelial‐mesenchymal transition; LATS1, large tumor suppressor kinase 1; miRNA, microRNA; PTEN, phosphatase and tensin homolog; TGF, transforming growth factor.