Table 2.
Main circRNAs associated with TNBC
| circRNA | Study (year) reference | Expression change | Hallmarks of cancer | Target microRNA | Target gene | Mechanism |
|---|---|---|---|---|---|---|
| circSEPT9 | Zheng et al. (2020)76 | ↑ | proliferation (+); invasion (+); migration (+); apoptosis (−) | miR-637 | LIF | circSEPT9 functions as a sponge of miR-637 to downregulate the LIF and activate LIF/Stat3 signaling pathway to promote TNBC progression |
| circUBE2D2 | Dou et al. (2020)84 | ↑ | tumorigenesis (+); proliferation (+); invasion (+); migration (+) | miR-512-3p | CDCA3 | circUBE2D2 functions as a sponge of miR-512-3p for upregulation of CDCA3 to promote TNBC progression and doxorubicin resistance |
| circHER2 | Li et al. (2020)98 | ↑ | tumorigenesis (+); proliferation (+); invasion (+) | NA | HER2-103 | CircHER2 encodes a HER2-103 protein to promote TNBC progression |
| circAGFG1 | Yang et al. (2019)99 | ↑ | tumorigenesis (+); proliferation (+); invasion (+); migration (+) | miR-195-5p | CCNE1 | circAGFG1 acts as a ceRNA of miR-195-5p to relieve the repressive effect of miR-195-5p toward CCNE1 |
| circKIF4A | Tang et al. (2019)100 | ↑ | proliferation (+); migration (+) | miR-375 | KIF4A | circKIF4A functions as a sponge of miR-375 to regulate the expression of KIF4A |
| circPLK1 | Kong et al. (2019)101 | ↑ | proliferation (+); migration (+) | miR-296-5p | PLK1 | circPLK1 functions as a sponge of miR-296-5p to regulate PLK1 |
| circRNA_069718 | Zhang et al. (2019)89 | ↑ | proliferation (+); invasion (+); EMT (+) | NA | Wnt/β-catenin pathway-related genes | circRNA_069718 regulates the expression levels of Wnt/β-catenin pathway-related genes (e.g., β-catenin, c-myc, and cyclin D1) |
| circRAD18 | Zou et al. (2019)82 | ↑ | proliferation (+); migration (+); apoptosis (−) | miR-208a/miR-3164 | IGF1/FGF2 | circRAD18 functions as a sponge of miR-208a and miR-3164 to upregulate IGF1 and FGF2 expression and promote TNBC progression |
| circANKS1B | Zeng et al. (2018)83 | ↑ | invasion (+); migration (+); EMT (+) | miR-148a-3p/miR-152-3p | USF1 | circANKS1B functions as a sponge of miR-148a-3p and miR-152-3p to increase the expression of transcription factor USF1 and promote EMT |
| circEPSTI1 | Chen et al. (2018)143 | ↑ | proliferation (+); invasion (+); apoptosis (−) | miR-4753/miR-6809 | BCL11A | circEPSTI1 functions as a sponge of miR-4753 and miR-6809 to regulate BCL11A expression and affect TNBC proliferation and apoptosis |
| circUBAP2 | Wang et al. (2018)144 | ↑ | proliferation (+); migration (+); apoptosis (−) | miR-661 | MTA1 | circUBAP2 functions as a sponge of miRNA-661 to increase the expression of the oncogene MTA1 |
| ciRS-7 | Sang et al. (2018)102 | ↑ | invasion (+); migration (+) | miR-1299 | MMPs | ciRS-7 functions as a sponge of miR-1299 to enhance the expression of MMPs |
| circGFRA1 | He et al. (2017)85/Zheng et al. (2021)86 | ↑ | proliferation (+); invasion (+); apoptosis (−) | miR-34a/miR-361-5p | GFRA1 | circGFRA1 functions as a sponge of miR-34a to regulate GFRA1 expression/functions as a sponge of miR-361-5p for promoting the resistance of TNBC to PTX |
| circNR3C2 | Fan et al. (2021)145 | ↓ | proliferation (−); invasion (−); migration (−); EMT (−) | miR-513a-3p | HRD1 | circNR3C2 functions as a sponge for miR-513a-3p to downregulate HRD1 to promote tumor growth and metastasis |
| circITCH | Wang et al. (2019)146 | ↓ | proliferation (−); invasion (−); migration (−) | miR-214/miR-17 | ITCH1 | circITCH functions as a sponge for miR-214 and miR-17 to increase expression of its ITCH linear isoform and inactivate Wnt/β-catenin signaling |
| circTADA2A-E6 | Xu et al. (2019)103 | ↓ | proliferation (−); invasion (−); migration (−); | miR-203a-3p | SOCS3 | circTADA2A-E6 functions as a sponge of miR-203a-3p to restore the expression of SOCS3, resulting in a less aggressive oncogenic phenotype |
| circFBXW7 | Ye et al. (2019)94 | ↓ | proliferation (−); invasion (−); migration (−); | miR-197-3p | FBXW7 | circFBXW7 functions as a sponge of miR-197-3p to suppresses TNBC growth or encodes the FBXW7-185aa protein to inhibit the proliferation and migration abilities of TNBC cells |
↑, upregulated; ↓, downregulated; (+), promoted; (−), inhibited; EMT, epithelial-mesenchymal transition; LIF, leukemia inhibitory factor; NA, not applicable.