Figure 1.

Hypoxia-inducible factor (HIF)-1α is involved in the hypoxia-induced CAIX expression and glioblastoma multiforme (GBM) migration. U87 (A) and U251 (C) were transfected with a dominant-negative mutant of HIF-1α (1 or 2 μg) for 24 h and exposed to hypoxia (1% oxygen (O₂)) for another 24 h. The quantitative results are shown in a bar graph (B,D). (E) U87 was treated with an HIF-1α inhibitor (10 μM) for 30 min and exposed to hypoxic conditions (1% O₂) for another 24 h. The quantitative results are shown in a bar graph (F). (G) U87 was treated with dimethyloxalylglycine (50 or 100 μM) for 24 h. HIF-1α and CAIX protein expression were determined by Western blotting using whole cell lysates. The quantitative results are shown in a bar graph (H). (I) U87 cells were treated with an HIF-1α inhibitor (10 μM) for 30 min and exposed to hypoxic conditions (1% O₂), and in vitro migration activities were measured after 24 h with a transwell assay and then visualized using a digital camera. (J) The quantification of U87 migration by the number of cells that migrated to the underside of the filter. (K) U87 cells were transfected with CAIX luciferase reporter plasmids for 24 h, treated with an HIF-1α inhibitor (10 μM) for 30 min, and exposed to hypoxic conditions (1% O₂). Firefly luciferase activities were measured after 24 h, and the results were normalized to the renilla luciferase activity. * p < 0.05 compared with the normoxia control group. # p < 0.05 compared with the hypoxia group. A two-way analysis of variance with a post-hoc Bonferroni test was used to examine the significance of the mean. Quantitative data are presented as the mean ± standard error (representative of n = 3). (L) Pearson’s correlation analysis between HIF-1α and CAIX expression in human glioma microarray dataset GSE4290 (r = 0.2846, p < 0.001).