Figure 7.

GDF15 promotes angiogenesis by stimulating VEGFA secretion in the brain tumor. (A) Representative section of the brain tumors from mice injected with control U373 cells and rhGDF15-stimulated U373 cells. The brain sections were stained with hematoxylin and eosin. The brain tumor area was measured using ImageJ. (B) VEGFA (green) and CD31-positive endothelial cells (red) in mouse brain tumor tissues were analyzed using immunofluorescence staining. Microvessel density was counted as the number of CD31-positive vessels. Scale bar = 100 µm. (C) Representative image of immunofluorescence analysis of the phosphorylation of MAPK1 (p-MAPK1; upper panel; green) and expression of SP1 (upper panel; green) counterstained with 4′,6-diamidino-2-phenylindole (DAPI) (blue). Scale bar = 100 µm. Fluorescence intensity was calculated using ImageJ as follows: Corrected total cell fluorescence = integrated density − (area of selected cell × mean fluorescence of background readings). Data are presented as the mean ± standard (control group, n = 5; rhGDF15-treated group; n = 6), * p < 0.05 and ** p < 0.01 compared with control group.