BDNF and urinary bladder cancer: Specifically, two circRNAs, namely, cTFRC and circTCF25, were reported to sequester miR-107 in bladder cancer cells, thus favoring cell cycle progression (Zhong et al., 2016; Su et al., 2019), while in gastric cancer, circHIPK3 was shown to sponge miR-107, enabling the release of brain-derived neurotrophic factor (BDNF) expression (Wei et al., 2020).