Hsa_circ_0007380 silencing restrains the growth and enhances radiosensitivity in esophagus cancer by miR-644a/Spindlin 1 axis

Circular RNAs are frequently dysregulated and show important regulatory function of tumorigenesis in cancers. Hsa_circ_0007380 was found to be elevated in human radioresistant esophageal cancer cells. Here, this study aimed to investigate the action and mechanism of hsa_circ_0007380 in esophageal cancer carcinogenesis and radiosensitivity. Quantitative real-time PCR and western blotting were performed to detect levels of genes and proteins. Functional experiments were conducted using MTT assay, EdU assay, clonogenic survival assay, flow cytometry and murine xenograft model assay, respectively. The binding between miR-644a and hsa_circ_0007380 or spindlin1 (SPIN1) was validated using dual-luciferase activity assay. Hsa_circ_0007380 was highly expressed in esophagus cancer tissues and cells, knockdown of hsa_circ_0007380 suppressed esophagus cancer cell proliferation, induced apoptosis and enhanced radiosensitivity in vitro, and the same effects were also confirmed in nude mice. Mechanistically, hsa_circ_0007380 sequestered miR-644a to release SPIN1 expression, implying the hsa_circ_0007380/miR-644a/SPIN1 competing endogenous RNA network esophagus cancer cells. miR-644a was decreased in esophagus cancer, re-expression of miR-644a restrained cell growth and conferred radiosensitivity in esophagus cancer, which were reversed by SPIN1 overexpression. Besides that, inhibition of miR-644a abolished the promoting action of hsa_circ_0007380 knockdown on esophagus cancer apoptosis and radiosensitivity. Hsa_circ_0007380 silencing impedes cell growth and reinforces radiosensitivity in esophagus cancer by miR-644a/SPIN1 axis, suggesting a promising therapeutic target for esophagus cancer combined treatment.