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

ABSTRACT 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.