Phosphoenolpyruvate carboxykinase 2 activation of the AMPK–CEBPB axis to enhance glutamine utilization to promote glycolysis and malignant behavior in adenocarcinomas cells under glucose deprivation

Abstract

Glucose deprivation (Glu-D) is a critical feature of the tumor microenvironment. Under such conditions, tumor cells seek alternative metabolic resources to maintain rapid growth and proliferation. Glutamine serves as a key alternative resource for cancer cells, yet the metabolic mechanisms involving its transporters in non-small cell lung cancer remain poorly understood. Lentiviral vectors for overexpression and knockdown of phosphoenolpyruvate carboxykinase 2 (PCK2), solute carrier family 38 member 2 (SLC38A2), and CEBPB were constructed. Transwell, flow cytometry, Western blotting, and dual-luciferase reporter assays were used to investigate the regulatory relationship between PCK2 and SLC38A2 under Glu-D, as well as their effects on cellular glutamine metabolism, glycolysis, and malignant cell behaviors. PCK2 and SLC38A2 were highly expressed in human adenocarcinomas tissues. PCK2 upregulated SLC38A2 expression, though this effect was indirect. Under Glu-D, knockdown of PCK2 or SLC38A2 significantly reduced cellular glutamine utilization, inhibited glycolysis, and suppressed malignant cell behaviors. Treatment with an AMP-activated protein kinase (AMPK) inhibitor or knockdown of CEBPB produced similar effects. PCK2 activated AMPK, which increased downstream SLC38A2 expression by activating the transcription factor CEBPB. PCK2 upregulates SLC38A2 expression via the AMPK–CEBPB axis, enhancing glutamine utilization to promote glycolysis and malignant behaviors in A549 cells under Glu-D.