Fig. 6

Cell migration, invasion and metastasis can be regulated by Slug SUMOylation. a Effect of hypoxia on the migration of cells expressing wild-type Slug or Slug5M. Successfully lentiviral infected HEK293/ Ctrl, Slug and Slug5M cells were cultured for 24 h and treated with hypoxia for an additional 4 h. Phase contrast images were captured at the beginning (0 h) and after 8 h of the cell migration assay using standard culture inserts. The migratory ability of the cells is presented in the Left panel, and the control group exposed to normoxia was normalized to 100%. b Cell invasion was assessed using the Matrigel-coated transwell system. The invasive cells were calculated and normalized to the results for control cells exposed to normoxia. The values are presented as the means ± SEM (n = 3). The right panel shows the fold-change in the number of invasive cells for each cell line under hypoxia compared to normoxia. c, d Mice were injected into the tail vein with HEK293 or CL1–2 cells overexpressing the control (Ctrl) or the wild-type (Slug) or mutant form (Slug5M). The number of lung metastatic nodules (arrowhead) was measured in 9 (c) or 7 (d) mice per group. The nature of the nodules was confirmed by hematoxylin and eosin staining. The error bars indicate the mean values ± SEM, and P values were calculated using Student’s t-test. The asterisk represents the P value of < 0.05 for the comparison of the labeled group to the control group. Scale bar: 2 mm in lung photo and 200 μm in HE staining. e, f Kaplan-Meier estimates of overall survival in NSCLC patients. The mRNA (e) and protein (f) levels of Slug and Ubc9 were determined via Q-PCR and immunohistochemistry, respectively (left and middle graphs, respectively). The patients were divided into the high- (red line) and low-expression (blue line) groups. The graph on the right shows the combined effect of Slug and Ubc9 on the overall survival of NSCLC patients. P values were calculated using the log rank test