A comparative pharmaco-metabolomic study of glutaminase inhibitors in glioma stem-like cells confirms biological effectiveness but reveals differences in target-specificity

Abstract

Cancer cells upregulate anabolic processes to maintain high rates of cellular turnover. Limiting the supply of macromolecular precursors by targeting enzymes involved in biosynthesis is a promising strategy in cancer therapy. Several tumors excessively metabolize glutamine to generate precursors for nonessential amino acids, nucleotides, and lipids, in a process called glutaminolysis. Here we show that pharmacological inhibition of glutaminase (GLS) eradicates glioblastoma stem-like cells (GSCs), a small cell subpopulation in glioblastoma (GBM) responsible for therapy resistance and tumor recurrence. Treatment with small molecule inhibitors compound 968 and CB839 effectively diminished cell growth and in vitro clonogenicity of GSC neurosphere cultures. However, our pharmaco-metabolic studies revealed that only CB839 inhibited GLS enzymatic activity thereby limiting the influx of glutamine derivates into the TCA cycle. Nevertheless, the effects of both inhibitors were highly GLS specific, since treatment sensitivity markedly correlated with GLS protein expression. Strikingly, we found GLS overexpressed in in vitro GSC models as compared with neural stem cells (NSC). Moreover, our study demonstrates the usefulness of in vitro pharmacometabolomics to score target specificity of compounds thereby refining drug development and risk assessment.

Metabolic characterization of aggressive breast cancer cells exhibiting invasive phenotype: Impact of non-cytotoxic doses of 2-DG on diminishing invasiveness

“…Glutamine can be a primary source fueling the TCA cycle (23)(24). A recent study has shown that GLS inhibitor was effective in diminishing cell growth by limiting in ux of glutamine derivatives into the TCA cycle, but this effect was only detected in the cells which have high levels of GLS, suggesting that the role of glutamine for TCA cycle is cell line-speci c (50). In this study, we used glutamine free media or GLS1 inhibitor (CB-839) to investigate the role of glutamine-TCA cycle pathway in SUM149.…”

Targeting Metabolism in Cancer Cells and the Tumour Microenvironment for Cancer Therapy

“…Glutamine deprivation was found to diminish the proportion of CSC-like cells in various cancers including NSCLC, pancreatic cancer, and GBM [ 212 ]. Pharmacological inhibition of GLS was also shown to be effective in eradicating the GBM stem-like cell population, which is thought to be responsible for therapy resistance and tumour recurrence [ 213 ].…”

Metabolic characterization of aggressive breast cancer cells exhibiting invasive phenotype: impact of non-cytotoxic doses of 2-DG on diminishing invasiveness

“…Glutamine can be a primary source fueling the TCA cycle [22,23]. A recent study has shown that GLS inhibitor was effective in diminishing cell growth by limiting influx of glutamine derivatives into the TCA cycle, but this effect was only detected in the cells which have high levels of GLS, suggesting that the role of glutamine for TCA cycle is cell line-specific [48]. In this study, we used glutamine free media or GLS1 inhibitor (CB-839) to investigate the role of glutamine-TCA cycle pathway in SUM149.…”