FIG. 1.

TSA represses HIF-1α induction in response to hypoxia. A. Dose responses. U-87 cells were exposed to hypoxia (1% O₂) for 8 h in the presence of increasing concentrations of TSA. Cell lysates (40 μg) were analyzed by Western blotting using anti-HIF-1α and tubulin (Tub) monoclonal antibodies. B. Time course. U-87 cells were exposed to 300 nM of TSA and 1% O₂ for 4 or 8 h, and HIF-1α levels were analyzed by Western blotting. C. Tumor cell lines. Different cell lines were exposed to dimethyl sulfoxide or 300 nM of TSA for 8 h under 1% O₂. D. Effect of TSA on gene expression. Total RNA from U-87 cells exposed to dimethyl sulfoxide or TSA for 8 h under conditions of 21% or 1% O₂ was analyzed by RT-PCR using primers described in Materials and Methods. VEGF, vascular endothelial growth factor.