Abstract:Objective To explore the mechanism of SCO2 in mediating the migration and infiltration of breast cancer MDA-MB-231 cells.Methods The breast cancer cell line MDA-MB-231 was used as the model, and transient transfection to interfere with the expression of SCO2 was performed, where cells were divided into a control group (si-NC group) and an interference group (si-SCO2 group). The effect of SCO2 interference was detected by quantitative real-time polymerase chain reaction and Western blotting. Expression of SCO2 was rescued by adding small extracellular vesicles secreted by untreated MDA-MB231 cells to the cells in the si-SCO2 group, and the cells were divided into a control group (si-NC group), an interference group (si-SCO2 group) and a rescue group (si-SCO2 + NC-sEVs group) based on the treatment. The SCO2 overexpression plasmid was further constructed and transfected into cells, and the control group (OE-NC group) and the overexpression group (OE-SCO2 group) were established. All groups of cells were tested for the migration and invasion ability by the scratch assay and the Transwell invasion assay, respectively.Results The relative mRNA and protein expressions of SCO2 in the si-SCO2 group were lower than those in the si-NC group (P < 0.05). The cell migration rate in the si-SCO2 group was lower than that in the si-NC group (P < 0.05), and the number of invasive cells in the si-SCO2 was lower than that in the si-NC group (P < 0.05). The number of invasive cells in the si-SCO2+NC-sEV group was higher than that in the si-SCO2 group (P < 0.05). The relative mRNA and protein expressions of SCO2 in the OE-SCO2 group were higher than those in the OE-NC group (P < 0.05). The cell migration rate in the OE-SCO2 group was higher than that in the OE-NC group (P < 0.05), and that the number of invasive cells in the OE-SCO2 group was higher than that in the OE-NC group (P < 0.05).Conclusions Knockdown of SCO2 weakens the migration and infiltration ability of MDA-MB-231 cells, while overexpression of SCO2 promotes the migration and infiltration ability of breast cancer MDA-MB-231 cells. SCO2 is expected to be a regulatory target for the treatment of breast cancer metastasis.