High hsa_circ_0001944 Expression Predicts Unfavorable Prognoses in Bladder Cancer

Abstract Background: Bladder cancer (BC) is a common genitourinary malignancy worldwide. Circular RNAs (circRNAs) participate in the cancer developments, including BC; thus, roles of circRNAs in this process have attracted significant attention. Methods: In this study, high-throughput sequencing was used for circRNA expression profiles analysis in BC tissues. We performed RT-qPCR to determine hsa_circ_0001944 expression regarding BC tissues. We used fluorescence in situ hybridization (FISH) to detect hsa_circ_0001944 expression and hsa_circ_0001944 subcellular localization in BC tissues. hsa_circ_0001944 expression in BC cells was selectively regulated. We employed CCK8, transwell, and wound healing assays to monitor the cell proliferation and invasion, respectively. We employed dual-luciferase reporter and RNA pulldown assays to verify the relationship among hsa_circ_0001944, miR-548, and PROK2. We examined the hsa_circ_0001944 effects on BC cell metastasis and proliferation in vivo through a subcutaneous xenograft model as well as an intravenous tail injection model of nude mice. Results: The result show that hsa_circ_0001944 expression increased significantly in BC samples. Furthermore, high hsa_circ_0001944 expression predicted unfavorable prognoses in BC. Functional assays validated that downregulating hsa_circ_0001944 decreased BC invasion and proliferation in vivo and in vitro . Further studies showed that hsa_circ_0001944 expression promoted BC progression via sponging miR-548 and enhancing PROK2 expression. Luciferase reporter experiments validated the interactions between hsa_circ_0001944, miR-548, and PROK2. This study also found that downregulating miR-548 or overexpressing PROK2 restored BC cell invasion and proliferation after silencing hsa_circ_0001944. Conclusions: Taken together, we found hsa_circ_0001944 is a tumor-promoting circRNA in BC that functions like a competing endogenous RNA to regulate PROK2 expression via sponging miR-548.