Figure 7. Loss of HIF-1α was correlated with metabolic changes in sarcoma cells in response to irradiation.

Primary cells from P7NP and P7NPH1 tumors were isolated as described in Figure 3. All experiments were performed with in vitro cultures under 21% oxygen. A) Cells were irradiated with 6Gy and lysates were collected at the indicated times after irradiation, and intracellular lactate was measured with mass spectrometry. The results showed P7NP cells had significantly increased intracellular lactate content at 24 hours after irradiation, both compared to nonirradiated P7NP cells and compared to P7NPH1 cells by a two-tailed student t-test. B) Cells were irradiated with 6Gy and lysates were collected at the indicated times after irradiation, and extracellular lactate was measured with the lactate colorimetric kit. The results showed P7NP cells had significantly increased extracellular lactate content at 0 and 2 hours after irradiation as compared to P7NPH1 cells by a two-tailed student t-test. (C–G) Oxygen consumption rates (OCR) were measured in cells that were irradiated at 6Gy at indicated times after irradiation. DMSO, oligomycin (Oligo), FCCP, antimycin A (Anti A), rotenone (Rot), and 2-deoxyglucose (2-DG) were added at indicated times. C) P7NP and P7NPH1 cells had similar OCR at baseline. D) P7NP and P7NPH1 cells both had reduced OCR at 8 hours following irradiation. E) P7NPH1 cells restored maximal electron transport chain (ETC) activity at 24 hours following irradiation and has more reserve capacity as compared to P7NP cells by two-tailed student t-test. F) P7NP cells restored maximal ETC activity at 72 hours following irradiation. G) Respiration in P7NP or P7NPH1 cells at 24 hours after irradiation was not inhibited by 2-DG. * p<0.05.