ZBTB7A governs 2-DG-inhibited glycolysis by regulating GLUT1 in nasopharyngeal carcinoma

Abstract

Our previous studies suggested a potential interaction between the POK erythroid myeloid ontogenic factor ZBTB7A and glucose transporter 1 (GLUT1) in nasopharyngeal carcinoma (NPC). This study was designed to confirm the interaction and further evaluate the precise mechanism by which ZBTB7A and GLUT1 regulate NPC development. The binding sites between ZBTB7A and the promoter of GLUT1 were predicted by bioinformatics. Gene expression was measured by quantitative real-time polymerase chain reaction (qPCR), western blotting, and immunohistochemistry. The activities of key glycolysis enzymes, including hexokinase (HK), pyruvate kinase (PK), lactate dehydrogenase (LDH), and lactate, were detected using specific enzyme-linked immunosorbent assay kits. The connection between ZBTB7A and GLUT1 was analyzed by dual-luciferase reporter assay and chromatin immunoprecipitation–qPCR. The vitality, proliferation, and tumorigenicity of the cells expressing different levels of ZBTB7A were tested by adding the glycolysis inhibitor 2-deoxy-D-glucose (2-DG), followed by MTT, colorimetric focus forming, and xenograft assays, respectively. Our results showed that high expression of GLUT1 was associated with late-stage NPC. After constructing stably transfected cells with lentiviruses, ZBTB7A was effectively knocked down in 5-8F cells (RNAi-5-8F) and overexpressed in 6-10B cells (ZBTB7A-6-10B). The up- or downregulation of GLUT1 secondary to ZBTB7A changes was also limited. The vitality and proliferation of the cells expressing low ZBTB7A were notably blocked by 2-DG. The cells expressing high ZBTB7A were not very sensitive to 2-DG. The growth of RNAi-5-8F xenografts was strongly suppressed by 2-DG. The activities of HK, PK, and LDH were suppressed by 2-DG in the cells expressing low ZBTB7A. RNAi-5-8F cells had the lowest 2-DG-induced lactate production. ZBTB7A directly suppressed the promoter region of GLUT1 to regulate GLUT1 expression. Thus, ZBTB7A controls the 2-DG-induced inhibition of glycolysis by affecting GLUT1.