Table 2.

The emerging roles of Angio-CircRs in various cancers

Mechanism/level	circRNA	Expression	Function	Molecular mechanism	Cancer type	Refs.
Epigenetic and transcriptional regulation	circ-CCAC1	up	pro-angiogenesis	Increases SH3GL2 expression by sequestering EZH2 in the cytoplasm	CCA	12
Splicing and mRNA stability	circSMARCA5	down	anti-angiogenesis	interacts with SRSF1 to regulate VEGFA mRNA Splicing	GBM	114
	circPOK	up	pro-angiogenesis	promotes the ILF2/3 complex to bind and stabilize interleukin (IL)-6 and VEGF mRNA	mesenchymal tumor	115
Interacting with RBPs	circRhoC	up	pro-angiogenesis	directly binds and modulates VEGFA expression, sponges miR-302e to regulate VEGFA expression	ovarian cancer	57
	circ-GLI1	up	pro-angiogenesis	interacts with p70S6K2 to upregulate Cyr61 via inducing activation of Hedgehog/GLI1 and Wnt/β-catenin pathways	melanoma	116
Sequestering miRNAs	circ-ATXN1	up	pro-angiogenesis	sponges miR-526b-3p to upregulate the expression of MMP2/VEGFA	glioma	117
	circSCAF11	up	pro-angiogenesis	sponges miR-421 to promote SP1 expression, which activates the transcription of VEGFA	glioma	118
	circRNA-MYLK	up	pro-angiogenesis	sponges miR-29a to trigger VEGFA/VEGFR2 and the downstream Ras/ERK signaling pathway	bladder carcinoma	119
	circ0001429	up	pro-angiogenesis	sponges miR-205-5p to increase VEGFA expression	bladder cancer	120
	circCCT3	up	pro-angiogenesis	sponges miR-613 to upregulate VEGFA and WNT3 expression	CRC	121
	circ_0056618	up	pro-angiogenesis	sponges miR-206 to upregulate CXCR4 and VEGFA	CRC	122
	circHIPK3	down	anti-angiogenesis	sponges miR-558 to inhibit the expression of HPSE	bladder cancer	123

Expression is in relation to normal tissue. These studies used human tissue samples. All circRNAs were measured with qRT-PCR in these studies. GBM, glioblastoma multiforme; PDAC, pancreatic ductal adenocarcinoma.