EFFECT OF LACTATE DEHYDROGENASE INHIBITION BY OXAMATE ON LEWIS LUNG CARCINOMA CELLS WITH DIFFERENT METASTATIC POTENTIAL.

Background: Today, the ability for metabolic reprogramming is considered one of the distinguishing features of metastatically active tumor cells, a classic example of which is aerobic glycolysis. Despite a large number of studies in this direction, the question of the relationship between the intensity of aerobic glycolysis and the metastatic potential of tumor cells remains almost completely open. The work aimed to investigate the effect of the lactate dehydrogenase (LDH) inhibitor on the viability and several characteristics of Lewis lung carcinoma cells with different metastatic potential.

Materials and methods: High-metastatic (LLC) and low-metastatic (LLC/R9) variants of Lewis lung carcinoma cells were used. After 24 h of tumor cells incubation with or without 40 mM sodium oxamate, cell viability, the concentration of glucose and lactate in the incubation medium, distribution of cells by the cell cycle phases, and intracellular ROS production were estimated.

Results: It was revealed that regardless of the metastatic potential, LLC cells are heterogeneous in terms of both the involvement of aerobic glycolysis in their growth and survival processes and the sensitivity to the cytotoxic/cytostatic action of an LDH inhibitor. 35% of cells of either LLC variant form an oxamate-resistant subpopulation while 65% are oxamate-sensitive. The rate of glucose consumption of LLC/R9 cells in the absence of oxamate is almost twice higher compared to LLC and, as a result, the sensitivity of these cells to the cytotoxic/cytostatic effect of oxamate also is significantly higher (the IC50 for LLC/R9 cells is by 35.8% lower than that for LLC cells, p < 0.05). Approximately one-third of the cells of both LLC and LLC/R9 variants can survive and proliferate when aerobic glycolysis is completely inhibited by oxamate. This indicates metabolic reprogramming (either pre-existing or dynamically arising in response to inhibition of glycolysis) of this subpopulation of cells, within which not only the survival of cells but also their proliferative activity is most likely based on glutamine metabolism.

Conclusions: Such metabolic heterogeneity of metastatically active cells indicates that inhibition of glycolysis as monotherapy is insufficient for effective antimetastatic therapy. Presumably, more effective would be to involve various inhibitors of metabolic processes that ensure the metabolic plasticity of metastatic cells.