Glutaminase inhibitor CB-839 causes metabolic adjustments in colorectal cancer cells

Colorectal cancer (CRC) cells are ‘addicted’ to glutamine to satisfy energy and biosynthetic needs. Inhibiting glutamine metabolism enzymes, like glutaminase, is a potential cancer therapy strategy. Although the GLS inhibitor CB-839 is being evaluated in clinical trials, a comprehensive assessment of its antitumor activity in CRC cells is crucial. The present study aimed to evaluate the impact of CB-839 treatment on different CRC cell lines in terms of survival and proliferation. Furthermore, metabolic adaptations resulting from CB-839 treatment, particularly in energetic pathways, were investigated. Three CRC cell lines (HCT116, HT29, and SW480) were treated with different CB-839 concentrations. Cytotoxicity was assessed via MTT assay, proliferation capacity by flow cytometry, and ATP production rates by Seahorse XF analysis. Moreover, metabolomic profile was explored with untargeted GC-MS and 1H-NMR, and targeted analysis of the Krebs cycle was conducted using GC-MS/MS. HT29 cells exhibited the highest sensitivity to CB-839. Subsequent experiments focused on HT29 and SW480 cells. CB-839 treatment altered cell cycle progression and increased glycolytic ATP production in HT29 cells. Metabolomic analysis revealed changes in Krebs cycle and glutaminolysis in both cell lines, along with alterations in amino acids, sugars, antioxidants, and organic acid levels. This study highlighted glutamine’s key role in CRC cells and provided a foundation for elucidating the mechanisms of response and resistance to CB-839.