The Promoting Effect of Radiation on Glucose Metabolism in Breast Cancer Cells under the Treatment of Cobalt Chloride

We aimed to investigate the influence of radiation on hypoxia-treated breast cancers cells and its underlying mechanism. We mimicked the hypoxic response in MCF-7 cells by the treatment of CoCl₂. Meanwhile, hypoxic MCF-7 cells induced by CoCl₂ or untreated MCF-7 cells were treated with or without radiation, and then treated with or without hypoxia inducible factors-1α (HIF-1α) inhibitor. Subsequently, glucose update and lactate release rate were determined by commercial kits, as well as the expressions of HIF-1α and the glucose metabolic pathway related genes, including fructose biphoshatase 1 (FBP1), glucose transporter 1 (GLUT1), lactate dehydrogenase A (LDHA), hexokinase 2 (HK2), and isocitrate dehydrogenase 2 (IDH20) were detected by western blotting and/or RT-PCR. The results showed that glucose uptake rate and lactate release rate were increased in cells under hypoxia and/or radiation condition compared with untreated cells (p < 0.05), while the addition of HIF-1α inhibitor decreased these rates in hypoxia + radiation treated cells (p < 0.05). In addition, compared with untreated cells, the mRNA and protein levels of HIF-1α were significantly increased under hypoxia and radiation condition (p < 0.05), while which decreased after the addition of HIF-1α inhibitor (p < 0.05). Similar content changing trends (all p < 0.05) were observed in FBP1, IDH2, GLUT1, and LDHA but not HK2. In conclusion, the combination of radiation and hypoxia could promote the glucose metabolism. Furthermore, HIF-1α might inhibit the promoting effect of radiation on glycolysis in hypoxic MCF-7 cells by regulating the glucose metabolic pathway.