Fig. 1.

Inhibition of HIF-1 transcriptional activity by anthracyclines. (A) effect of DNR or DXR on hypoxia-induced HIF-1 activity. (Top) HIF-1-dependent Luc activity was determined in Hep3B-c1 cells treated with 0, 0.2, or 1 μM DNR or DXR under 20% (open bars) or 1% (filled bars) O₂ for 24 h. Cells were lysed and analyzed for the ratio of firefly to Renilla Luc activity. (Middle and Bottom) HEK293 cells were exposed to 20% (open bars) or 1% (filled bars) O₂ for 24 h in the presence of 0, 0.2, or 1 μM DNR or DXR. Total RNA was isolated for determination of VEGF (Middle) and GLUT1 (Bottom) mRNA levels by qRT-PCR. The mRNA levels were normalized to the levels of 18S rRNA in each sample, and each value was expressed relative to the levels in vehicle-treated cells exposed to 20% O₂. Mean ± SEM are plotted (n = 4). *, P < 0.05; **, P < 0.01 (Student's t test). (B) effect of DNR or DXR on Luc activity mediated by cotransfection of expression vector encoding HIF-1α (Left, purple bars) or HIF-2α (Right, green bars). Mean ± SEM are plotted (n = 3). *, P < 0.05; **, P < 0.01 (Student's t test).