RETRACTED: hsa_circ_001653 Implicates in the Development of Pancreatic Ductal Adenocarcinoma by Regulating MicroRNA-377-Mediated HOXC6 Axis

Pancreatic ductal adenocarcinoma (PDAC) is an extremely aggressive pancreatic cancer with poor survival rate. Circular RNAs (circRNAs) signatures have been identified in some human cancers, but there are little data concerning their presence in PDAC. We investigated the role of hsa_circ_001653, a newly identified circRNA, in the development of PDAC. hsa-circ-001653 expression was measured in 83 paired normal and tumor tissues surgically resected from PDAC patients. Phenotypic changes of PDAC cells were evaluated by assays for cell viability, cell cycle, invasion, and apoptosis. Tube-like structure formation of human umbilical vein endothelial cells (HUVECs) was examined in the presence of PDAC cells. Cross-talk between hsa_circ_001653 and microRNA-377 (miR-377)/human homeobox C6 (HOXC6) was assessed using dual-luciferase reporter assay, Ago2 immunoprecipitation, and northern blot analysis. Nude mice were inoculated with human PDAC cells for in vivo analysis. hsa_circ_001653 was an upregulated circRNA in PDAC. Silencing of hsa_circ_001653 in PDAC cells via RNA interference inhibited cell viability, cell-cycle progression, in vitro angiogenesis, and invasive properties, showing a pro-apoptotic effect. hsa_circ_001653 was found to bind to miR-377, which in turn repressed HOXC6 expression. Inhibition of miR-377 by its specific inhibitor restored cell viability, cell-cycle progression, in vitro angiogenesis, and invasive properties in PDAC cells lacking endogenous hsa_circ_001653. When nude mice were inoculated with human PDAC cells, inhibition of hsa_circ_001653 had a therapeutic effect. Collectively, the present study provides an enhanced understanding of hsa_circ_001653 as a therapeutic target for PDAC.