Circular RNAs (circRNAs) have recently been confirmed to participate in different pathological processes, including cancer progression. However, the role and precise mechanism of action of the majority of circRNAs have not been elucidated in bladder cancer (BC). Here, we identified a novel circular RNA, termed circUBXN7, which was significantly downregulated in BC tissues compared with matched nontumor tissues. Importantly, we found that decreased circUBXN7 expression was associated with pathological stage, grade and poor prognosis of BC patients. Functional experiments showed that circUBXN7 overexpression dramatically inhibited proliferation, migration and invasion in vitro and suppressed tumor growth in vivo. Mechanistically, circUBXN7 could directly bind to miR-1247-3p and reverse the oncogenic effects induced by miR-1247-3p. Furthermore, B4GALT3 was predicted and confirmed to be a target of miR-1247-3p. Rescue experiments demonstrated that circUBXN7 abrogated miR-1247-3p-mediated inhibition of B4GALT3 expression. Finally, silencing of B4GALT3 promoted proliferation and invasion of BC cells; and partially abolished the tumor suppressive effects caused by circUBXN7. Taken together, our study revealed that circUBXN7 serves as a competitive endogenous RNA of miR-1247-3p to elevate B4GALT3 expression, consequently inhibiting cell viability and invasion in BC. The circUBXN7-miR-1247-3p-B4GALT3 regulatory network may provide a new perspective for gene-based treatment strategies for BC.
Keywords: B4GALT3; bladder cancer; circ0001380; circUBXN7; circular RNA; miR-1247-3p.