Figure 4.

Low-dose IR-induced metabolic changes and radiation resistance are mediated by HIF-1α. Human fibroblasts were treated with a dose of 0.1 Gy or sham treated. The cells were harvested 12 h later and subjected to HIF-1α (red) and DAPI (blue) immunostaining (a), western blot (b) or mRNA measurement by qRT-PCR (c). (d) Fibroblasts were treated with DMSO (-NAC) or 10 mM NAC (+NAC) for 1 h and then subjected to the treatment as in a. The cells were immunostained with HIF-1α. Fibroblasts were transfected with control (siGL2) or siHIF-1α. The HIF-1α knockdown efficiency is shown in Supplementary Figure 4B. The cells were treated as in a and mRNAs were extracted for qRT-PCR for the expression of the indicated metabolic genes (e) or GLUT1 and 3 (f). The numbers are fold change of the mRNA levels in 0.1 Gy-treated cells relative to sham-treated cells as mean±S.D. from three independent experiments. (g) siGL2 or siHIF-1α expressing cells were treated and subjected to the colony survival assay as described in Figure 3f. The numbers are mean±S.D. from three independent experiments, *<0.05, **<0.01