CB-839 induces reversible dormancy in lung tumor-cells
Azemat Jamshidi-Parsian1, Samir V Jenkins2, Amy Tran3
1Department of Environmental Health Sciences, University of Arkansas for Medical Sciences, Little Rock, AR, 72205, USA; Department of Radiation Oncology, University of Arkansas for Medical Sciences, Little Rock, AR, 72205, USA.
Abstract:
Glutaminase inhibitors are currently being explored as potential treatments for cancer. This study aimed to elucidate the molecular mechanisms underlying the effects of CB-839 on lung tumor cell lines compared to non-tumor cell lines. Viability assays based on NADPH-dependent dehydrogenases activity, ATP energy production, or mitochondrial reductase activity were used to determine that CB-839 caused significant tumor cell specific inhibition of cellular functions. Clonogenic survival assay revealed a dose dependent reduction in clonogenic survival of various lung tumor cells presenting estimated IC50 values between 10 and 90 nM, while no effect on non-tumor cells was observed. CB-839 led to a 20% reduction in glutaminase (GLS1, a mitochondrial enzyme that catalyzes the conversion of glutamine to glutamate) activity, and a dose-dependent reduced glutamine consumption in tumor cells and had no effect on non-tumor cells. Cell cycle analysis showed the CB-839 did not lead to cell cycle arrest. Apoptosis and necrosis assays revealed an only slight increase in apoptosis in tumor cells. Furthermore, a trypan blue exclusion assay revealed about 40% growth reduction in tumor cells at 0.1-1 μM CB-839 treatment. Surprisingly, treated cells resumed normal growth when re-plated in a drug-free medium, demonstrating reversibility. In hypoxic conditions, CB-839's effect on clonogenic survival was amplified in a dose dependent manner consistent with increased role of GLS1 for energy production under hypoxic conditions. In conclusion, these results suggest CB-839 efficacy is linked to temporary and reversible reduction in glutamine utilization suggesting induction of dormancy.
Insights
The glutaminase inhibitor CB-839 selectively reduces lung tumor cell function and survival by temporarily inhibiting glutamine metabolism. This reversible effect suggests CB-839 may induce cancer cell dormancy.
Area of Science:
- Oncology
- Molecular Biology
- Biochemistry
Background:
- Glutaminase inhibitors are investigated as cancer therapeutics.
- Understanding CB-839's molecular mechanisms in lung cancer is crucial.
Purpose of the Study:
- Elucidate CB-839's effects on lung tumor versus non-tumor cell lines.
- Investigate the molecular mechanisms of CB-839 action.
Main Methods:
- Cell viability assays (NADPH dehydrogenases, ATP, mitochondrial reductase).
- Clonogenic survival assays.
- Glutaminase activity and glutamine consumption assays.
- Cell cycle, apoptosis, necrosis, and trypan blue exclusion assays.
Main Results:
- CB-839 demonstrated tumor-specific inhibition of cellular functions and dose-dependent reduction in clonogenic survival (IC50: 10-90 nM).
- CB-839 reduced glutaminase (GLS1) activity and glutamine consumption in tumor cells, with no effect on non-tumor cells.
- Effects were reversible upon drug removal; efficacy was amplified under hypoxia.
- Minimal impact on cell cycle, apoptosis, or necrosis observed.
Conclusions:
- CB-839 exhibits tumor-specific efficacy through reversible glutamine metabolism inhibition.
- The drug's action suggests induction of cancer cell dormancy, particularly under hypoxic conditions.
