Figure 4.

RNASE4 overexpression promotes glioblastoma progression in vitro and in vivo. A. The efficiency of RNASE4 overexpression in U87MG cells was confirmed by Western blotting, with ACTIN serving as the internal control for cellular lysates, and Amido Black staining of total secreted proteins serving as the loading control for proteins in the conditioned medium. B. Cell proliferation curve based on viable cell counts from control or RNASE4-overexpressing U87MG cells for a period of 7 days was plotted (**P<0.01). C. Transwell migration and matrigel invasion assays were used to assess changes in cell motility of RNASE4-overexpressed cells. Graphs on the right depict the statistical results (**P<0.01). D. The effects of RNASE4 overexpression on U87MG cells were evaluated using a sphere formation assay under stem cell-selective culture conditions. The right panel displays the statistical results for the number of oncospheres (greater than 100 μm in size) in control versus RNASE4-overexpressing cells. Data are presented as mean ± SEM from three independent experiments (**P<0.01). Scale bar, 100 μm. E. Control or RNASE4-overexpessing U87MG cells (2 × 10⁶) were subcutaneously injected into NOD/SCID mice for monitoring of tumor growth. Tumors from the tumor-bearing mice (n=4 for each group) were collected as shown in the left panel image. Weights of the excised tumors were measured and plotted in the right panel, and statistical differences between the control group and the RNASE4-overexpression group were determined using Student’s t-test (**P<0.01).