Table 2.

Down-regulated circRNAs in PCa.

circRNA (Other terms)	Clinical Cases	Cell Lines	Target genes/Regulators/sponged miRNAs	Affected Signaling Pathway/Process	Findings on over-expressed or silenced circRNA in PCa cellular experiments	Ref. (s)
circ-ITCH	52 PCa tissues and paired NATs	C4-2, LNCaP, DU145, 22Rv1, VCaP, and RWPE-1	miR-17-5p/HOXB13 axis	–	circ-ITCH overexpression inhibited PCa cell proliferation and increased apoptosis in vitro, also repressed tumor growth in vivo.	(77)
	–	VCaP, DU 145, PC-3, 22RV1, and RWPE-1	miR-197	–	circ-ITCH overexpression inhibited cell proliferation and increased apoptosis in PC-3 cells.	(78)
	10 PCa tissues and paired NATs	PC3, LNCaP, and RWPE-1	miR-17	Wnt/β-Catenin and PI3K/AKT/mTOR	circ-ITCH overexpression suppressed PCa cell viability and invasion.	(79)
hsa_circ_0001206	50 PCa tissues and paired NATs	PC-3, DU145, and LNCaP, and RWPE-1	miR-1285-5p	–	hsa_circ_0001206 overexpression suppressed PCa cell proliferation, colony formation, migration, and invasion in vitro and also, tumor growth in vivo.	(80)
circAMOTL1L (has_circRNA_000350)	3 PCa patient tissues including 35 BPH tissues, 34 low-grade PCa tissues and 28 high-grade PCa tissues	PC3, LNCaP, 1 DU145, and RWPE-1	miR-193a-5p/protocadherin-α axis	–	circAMOTL1L knockdown promoted PCa cell migration and invasion in vitro and conversely, overexpression decreased tumor growth in vivo. circAMOTL1L regulates EMT-related genes.	(81)
circUCK2	–	C4-2	miR-767-5p/TET1 axis	–	circUCK2 overexpression inhibited PCa cell proliferation, and invasion in vitro and tumor growth in vivo.	(82)
circ_LARP4	55 PCa tissues and paired NATs	LNCaP, DU145, and 22Rv1	–	–	circ_LARP4 up-regulation suppressed PCa cell migration and invasion, also induced expression of tumor suppressor FOXO3.	(83)
circ-MTO1 (has_circ_0076979)	298 PCa tissues and paired NATs	DU-145, VCaP, PC‐3, and RWPE-1	miR‐630 and miR‐17‐5p	–	circ-MTO1 overexpression inhibited PCa cell proliferation and invasion.	(84)
circ_KATNAL1 (hsa_circ_0008068)	–	LNCaP, DU145, and PC3, and WPMY-1	miR-145-3p/WISP1 axis	–	circ_KATNAL1 overexpression suppressed PCa cell proliferation and invasion, and also, induced apoptosis. circ_KATNAL1 plays its role via regulatory effects on expression of caspases and matrix metalloproteases (MMPs).	(85)
circRNA17 (hsa_circ_0001427)	–	CWR22Rv1, C4–2, and 293T	miR-181c-5p/ARv7 axis	–	circRNA17 reversely regulates expression of androgen receptor variant-7 and accordingly, negatively affects PCa cells invasion and resistance to enzalutamide. circRNA17 overexpression inhibited tumor growth and metastasis in vivo.	(37)
circPSMC3	55 PCa tissues and paired NATs	DU145, PC3, LNCap and P69	DGCR8	–	circPSMC3 overexpression repressed PCa cell proliferation through negative regulation of cell cycle.	(86)
circDDX17	20 PCa tissues and paired NATs	22Rv1 and PC-3	miR-346/LHPP axis	–	circDDX17 overexpression inhibited PCa cell proliferation, migration, and EMT.	(85)
circSLC8A1 (hsa_circ_0000994)	15 PCa tissues and paired NATs	DU145, 22Rv1, LNCaP, PC-3 and WPMY-1	miR-21	MAPK and chemokine pathways	circSLC8A1 knockdown increased PCa cell proliferation and migration.	(87)
circCRKL (hsa_circ_0001206)	45 PCa tissues and paired NATs	DU145, C4- 2, 22Rv1, LNCaP, and RWPE-1	miR-141/KLF5 axis	–	circCRKL overexpression inhibited PCa cell migration and invasion via suppressing cell cycle and increased apoptosis in vitro and also, inhibited tumor growth in vivo.	(88)
circ_17720 and circ_14736	144 PCa tissues and paired NATs	PC3, DU145, C4-2, and LNCaP, and RWPE-1	–	–		(89)
hsa_circ_0075542	30 PCa tissues and paired NATs	LNCaP and PC3	miR-1197/HOXC11 axis	–	hsa_circ_0075542 overexpression inhibited cell proliferation, migration, and invasion and enhanced apoptosis	(90)
circSMARCA5	20 PCa tissues and paired NATs	RWPE-1, DU145, LNCaP, and PC3	miR-181b-5p + miR-17-3p/TIMP3 axis	–	circSMARCA5 overexpression inhibited PCa cell proliferation, migration, and invasion in vitro and suppressed tumor growth and metastasis in vivo.	(91)
circSLC8A1 (hsa_circ_0000994)	15 PCa tissues and paired NATs	WPMY-1, PC-3, 22Rv1, DU145, and LNCaP	miR-21	–	circSLC8A1 knockdown promoted PCa cell proliferation and migration	(87)