Glutaminase Expression in Canine Large-Cell Alimentary Lymphoma Cells and Effects of Glutaminase Inhibition by CB-839

Glutamine metabolism plays a crucial role in tumour progression, making glutaminase a promising therapeutic target in various human cancers. However, its role in canine large-cell alimentary lymphoma (AL) remains unclear. This study investigated glutaminase expression and the effects of a glutaminase inhibitor (CB-839) on canine large-cell AL cell lines. Western blotting analysed glutaminase expression in three canine large-cell AL cell lines (CLC, Ema and Nody-1) and peripheral blood mononuclear cells (PBMCs) isolated from eight clinically healthy dogs. Cell viability was determined in each cell line after treatment with varying concentrations (0-10 µM) of CB-839. Flow cytometry was used to analyse the cell cycle and assess annexin assays in each cell line following treatment with 1 µM of CB-839 or a vehicle control. Additionally, metabolome analysis was performed in Nody-1 cells after treatment with 1 µM of CB-839 or a vehicle control. Glutaminase expression was significantly higher in cell lines than in PBMCs. CB-839 suppressed cell proliferation in a dose-dependent manner, with CLC and Nody-1 cells exhibiting greater susceptibility than Ema cells. Flow cytometric analysis revealed that CB-839 induced G0/G1 phase arrest and apoptosis in susceptible cell lines. Metabolomic analysis revealed that CB-839 led to glutamine accumulation and depletion of key tricarboxylic acid cycle intermediates in Nody-1 cells. These findings indicate that glutamine metabolism is upregulated in canine large-cell AL and plays a crucial role in tumour cell growth and survival. Inhibiting glutaminase could serve as a promising therapeutic strategy for this disease.