[Hsa_circ_0006948 regulates the proliferation, migration and invasion in osteosarcoma by regulation of the expression of miR-490-3p target ATG7].

Objective: To investigate the effect of hsa_circ_0006948 (circ_0006948) on the proliferation, migration and invasion of osteosarcoma cells and the underlying mechanism. Methods: A total of 120 osteosarcoma tissues and 40 adjacent normal tissue samples were collected from patients admitted to the First People's Hospital of Shangqiu City from 2009 to 2015. Microarray analysis was performed to detect the differential expressions of circRNA in Saos-2 cell. The mRNA expressions of circ_0006948, microRNA (miR)-490-3p and autophagy-related protein 7 (ATG7) in osteosarcoma cells, NHOst cells, osteosarcoma tissues and adjacent tissues were detected by real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR). Cell clone formation assay was used to detect cell proliferation ability, Transwell assay was used to detect cell invasion ability, and cell scratch assay was used to detect cell migration ability. The interactions between circ_0006948 and miR-490-3p, miR-490-3p and ATG7 were detected by dual luciferase reporter gene assay. The correlation between miR-490-3p and ATG7 was analyzed by TargetScan database, and the expression levels of Bcl-2 and Bax proteins in cells were detected by western blot. Results: The mRNA expression levels of circ_0006948, miR-490-3p and ATG7 in SAOS-2 cells were significantly different from NHOst cells (P<0.01). The mRNA expression levels of circ_0006948, miR-490-3p and ATG7 in osteosarcoma tissues were significantly different from adjacent tissues (P<0.01). The numbers of cell clone, migration and mobility in circ_0006948-siRNA group were (32.78±1.76), (37.58±1.82) and (36.93±1.45)%, respectively, lower than (65.72±1.45), (78.63±1.93) and (65.32±1.74)% in the siRNA NC group (all P<0.01). The numbers of cell clone, migration and mobility in the miR-490-3p mimics group were (20.08±1.54), (30.24±1.78) and (21.15±1.68)%, respectively, lower than (60.36±1.83), (76.93±1.64) and (40.56±1.27)% in the mimics NC group (all P<0.01). The numbers of cell clone, migration and mobility in the miR-490-3p inhibitor+ siRNA NC group were (90.34±1.72), (120.89±2.34) and (70.83±1.93)%, respectively, higher than (61.27±1.73), (75.82±1.82) and (42.38±1.74)% in the inhibitor NC+ siRNA NC group (P<0.01). The numbers of cell clone, migration and mobility in the circ_0006948 siRNA+ miR-490-3p inhibitor group were (58.74±1.98), (73.46±1.04) and (40.35±1.72)%, respectively, lower than (90.34±1.72), (120.89±2.34) and (70.83±1.93)% in the miR-490-3p inhibitor+ siRNA NC group (P<0.01). The numbers of cell clone, migration and mobility in the ATG7 siRNA group were (20.56±1.87), (40.36±1.76) and (20.96±1.73)%, lower than (65.46±1.74), (90.87±2.32) and (40.87±2.03)% in the siRNA NC group (P<0.01). The absorbance of miR-490-3p mimics+ pcDNA-ATG7 group was 0.54±0.11, higher than (0.36±0.08) of miR-490-3p mimics group (P<0.05). The expression levels of Bax and Bcl-2 protein in Saos-2 cells of miR-490-3p mimics group were significantly different from mimics NC group (P<0.01). The protein expression levels of Bax and Bcl-2 in Saos-2 cells of miR-490-3p mimics + pcDNA-ATG7 group were significantly different from miR-490-3p mimics group (P<0.01). Conclusion: Circ_0006948 regulates ATG7 expression through miR-490-3p, therefore regulates the proliferation, migration and invasion of osteosarcoma cells.