Reprogramming of Glucose Metabolism Pathways in Triple-negative Breast Cancer Cells under Hypoxia / 中国生物化学与分子生物学报

ABSTRACT

Metabolic changes are recognized as one of the hallmarks of cancer cells. Previous studies have shown that hypoxia can change the glucose metabolism of cancer cells. However, the mechanisms still need to be studied in detail. In this study, by using RNA-Sequencing (RNA-seq) and bioinformatics analysis, we found that there is a significant change in the expression of 334 genes in BT549 cells and 215 genes in MDA-MB-231 cells induced by hypoxia at the mRNA level. Most of these genes were associated with glucose metabolism. RNA-seq data, Western blot, enzyme activity assays, and metabolite quantification experiments showed that the glucose uptake increased by elevating the expression of glucose transporter protein 1 (GLUT1) in BT549 cells and GLUT1 and GLUT3 in MDA-MB-231 cells induced by hypoxia. Hypoxia promotes glycolysis by increasing the expression of at least one isozyme or enzyme protein subunit of the enzymes that catalyze the each reaction in the glycolysis pathway, as well as the regulatory enzymes 6-phosphofructo-2-kinase/fructose-2, 6-biphosphatase 3 (PFKFB3) and 4 (PFKFB4) isozymes. Hypoxia increases the expression of pyruvate dehydrogenase kinase 1 (PDK1) and PDK3 and reduces the expression of isocitrate dehydrogenase 3(IDH3), succinate dehydrogenase subunit B(SDHB) and D(SDHD) to reduce the aerobic oxidation pathway. The expression of glucose-6-phosphate dehydrogenase (G6PD) and glycogen synthase was significantly increased to promote the pentose phosphate pathway and glycogen synthesis pathway. The mRNA levels of enzyme genes had no significant difference in gluconeogenesis and glycogenolysis. The breast cancer database suggests that the mRNA levels of the glucose metabolism enzymes were consistent in vivo and in vitro. Hypoxia regulates the reprogramming of glucose metabolism by altering the gene expression of isozymes or subunits of these enzymes. The study comprehensively analyzed the effects of hypoxia on the expression of all enzyme genes and major regulatory enzymes in six glucose metabolism pathways and provides an understanding of glucose metabolism in cancer cells under a hypoxia environment.