HIF-1-Dependent VEGF Reporter Gene Assay by a Stable Transformant of CHO Cells

For the establishment of a screening system to detect inhibitors of vascular endotherial growth factor (VEGF) expression, a stable transformant of Chinese hamster ovary cells was isolated and cloned by transfection of a hypoxia-inducible factor 1 (HIF-1)-dependent VEGF promoter reporter gene. The expression of the reporter gene in the clone cells, as measured by luciferase activity, was stable. Hypoxic responses were best observed at an initial cell density of 2×104/well. The maximal increase of luciferase activity was 30 fold. In the highest cell density of 8× 104/well (2.1×105/cm2), basal activity was increased 13-15 fold compared to that at the lower cell densities, and did not respond to hypoxia. Addition of CoC12, which is known to mimic hypoxia, increased luciferase activity more than 10 times in normoxia.