Figure 2.
Low-dose radiation induces a metabolic shift. Human fibroblasts were either sham treated (S) or irradiated at 0.1 Gy and 12 h after the treatment; (a) culture media from an equal number of fibroblasts (1 × 106) were collected for lactate measurement. The numbers are mean±S.D. from three independent experiments. *<0.05, **<0.01. (b) An aliquot of cells were harvested and mRNA were isolated for qRT-PCR analysis of MCT expression with 18 s as an internal standard. The numbers are fold change of MCT mRNA levels in 0.1 Gy relative to sham-treated cells as mean±S.D. from three independent experiments. (c) Glucose consumption was determined in cells as in a and the numbers are mean±S.D. from three independent experiments. (d) Fibroblasts were treated as in a and subjected to analysis using the XF Analyzer according to the manufacture's protocol (Seahorse Bioscience). The numbers are mean±S.D. from three independent experiments. (e–g). Fibroblasts treated as in a and the cells were incubated with [1,2-13C]-glucose for 15 min prior to metabolite extraction and targeted LC-MS/MS analysis. The ratio of 13C labeled to unlabeled (12C) metabolites was measured by LC-MS/MS are presented as mean±S.D. over three independent samples, *<0.05, **<0.01. Metabolites with P-values for pair-wise comparisons <0.05 are shown. (h) mRNAs as in b were analyzed with qRT-PCR for the expression of the indicated genes. The numbers are mean±S.D. from three independent experiments. (i) Cell lysates were analyzed by western blot with the indicated antibody. Human fibroblasts treated as in a were harvested 12 h after the treatment and analyzed by either qRT-PCR (j) or immunostaining (k) of GLUT-1 or 3